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Industrial Crops and Products 42 (2013) 202– 215

Contents lists available at SciVerse ScienceDirect

Industrial Crops and Products

journa l h o me pag e: www.elsev ier .com/ locate / indcrop

eview

tate-of-the-art of the Jatropha curcas productive chain:rom sowing to biodiesel and by-products

icla Contrana,∗, Laura Chessaa, Marcello Lubinoa, Davide Bellavitea,ier Paolo Roggeroa,b, Giuseppe Ennea

Desertification Research Group (NRD), University of Sassari, Viale Italia 57, 07100 Sassari, ItalyDipartimento di Agraria, University of Sassari, Via Enrico de Nicola 1, 07100 Sassari, Italy

r t i c l e i n f o

rticle history:eceived 6 March 2012eceived in revised form 25 May 2012ccepted 30 May 2012

eywords:hysic nutiodieselegetable oiland use

a b s t r a c t

In the forthcoming years, 1–2 million hectares of Jatropha curcas L. are expected to be annually planted,reaching 12.8 million hectares worldwide by 2015. This considerable expansion is due to its productsand byproducts multiple uses and its amazing adaptability. J. curcas oil extracted by seeds is a promisingrenewable feedstock for biodiesel production and, together with the oil extraction by-products, it can beused as cooking/lighting fuel, bio-pesticide, organic fertilizer, combustible fuel, and for soap making. Thecapability to grow on poor quality soils not suitable for food crop makes J. curcas a possible solution ofall the controversies related to biodiesel production. Furthermore, J. curcas contributes to mitigate envi-ronmental problems, such as marginal land or abandoned farmland reclamation. Nevertheless, J. curcasis not a “miracle tree”: (i) the full potential of J. curcas is far from being achieved and its talents are still

iomass to be supported by scientific evidences; (ii) J. curcas capabilities are not easily exploitable and applicablesimultaneously; (iii) its use is controversial and potentially unsustainable due to the current knowledgegaps about the impacts and potentials of J. curcas plantations. The aims of this review are to detail eachphase of J. curcas productive chain from sowing to biodiesel and by-products, in order to logically orga-

nize the knowledge around J. curcas system, and to compare potentialities and criticalities of J. curcas,highlighting the agronomical, management, and environmental issues which should be still investigated.

© 2012 Elsevier B.V. All rights reserved.

ontents

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2032. J. curcas botany, ecology, and agronomy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203

2.1. Botanical description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2032.2. Ecology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2042.3. Agronomic practices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204

3. J. curcas uses and products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2073.1. Environmental problem mitigation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2073.2. Live-fencing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2083.3. Medical use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2083.4. Food . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2083.5. Combustible fuel and charcoal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2083.6. Seed oil, seed cake and husk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 208

3.6.1. Oil extraction and by-products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2083.6.2. Products and uses of seed oil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2093.6.3. Products and uses of seed cake . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 212

3.6.4. Fruit husk and shell uses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4. Conclusion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

∗ Corresponding author. Tel.: +39 079213103; fax: +39 079229394.E-mail address: niclacontran@hotmail.com (N. Contran).

926-6690/$ – see front matter © 2012 Elsevier B.V. All rights reserved.ttp://dx.doi.org/10.1016/j.indcrop.2012.05.037

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 214

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 214

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. Introduction

In the last decades, Jatropha curcas L. has become popular thankso its wide capabilities and plethora of uses, including biodieselroduction (Fairless, 2007). J. curcas seeds contain about 25–35%f oil, which can be easily extracted and used both for biodieselroduction and as cooking/lighting fuel, medicine, bio-pesticide,nd for soap making. Additionally, the seed cake, an oil extractiony-product, can be used as organic fertilizer, combustible fuel, oror biogas production (IFAD-FAO, 2010). Along with these multi-le uses, the expectations around J. curcas come from the amazingdaptability of this stem succulent, perennial, and drought avoidantree even on low-nutrient soils and under arid and semi-arid con-itions (Achten et al., 2010). The capability to grow on poor qualityoils allows J. curcas to not directly compete against food crops. Fur-hermore, the plant itself offers the ecological advantage to mitigateoil degradation and to reclaim marginal land or abandoned farm-and, and it can also be used as live-fencing, acting like a livestocknd fire barrier to protect fields (Kumar and Sharma, 2008).

However, J. curcas is not a “miracle tree”. J. curcas capabilitiesre not easily exploitable and applicable simultaneously. For exam-le, since the lack of moisture and nutrients strictly influence plantield, trade-offs between marginal land reclamation and profitableil production have to be taken into consideration (Kant and Wu,011). For several reasons, both technical and economical, the fullotential of J. curcas is far from being achieved, and its talentsre still to be supported by scientific evidences (Divakara et al.,010). J. curcas is still an un-domesticated tree and its seed andil productivity is hugely variable. Almost every step of cultiva-ion is uncertain. The best management practices, the selection ofuitable plant material, and the potential environmental risks andenefits have to be still investigated to lay out coherent and realisticultivation plan.

The use of J. curcas oil as biodiesel source has several contro-ersial aspects, such as economic, social and environmental risks,hich join in the wider current debate on the biofuel production.dditionally, the current knowledge gaps about the impacts andotentials of J. curcas plantations make its cultivation potentiallynsustainable (Achten et al., 2010; Kant and Wu, 2011). The debatebout J. curcas is heated and several authors point out that theareless cultivation of this tree could lead to significant risks inhe economies of several countries and to the impoverishment ofocal populations (Fairless, 2007). Some of the countries with high-st economic growth rates, such as India and China, have stronglymbedded the production of J. curcas biodiesel within their energyolicies. In 2003, a two-phase governmental project was launched

n India for wide-spread cultivation of J. curcas on wasteland. Theroject aims at planting 12.5 million hectares on government landcross the country and then privatizing the production of J. cur-as biodiesel. In 2006, China government decided to meet 15% ofransportation energy needs with biofuel, leaning on the ambi-ious plan to raise 11 million hectares of J. curcas plantation on

arginal lands (Fairless, 2007). In this context, a massive plantingrogram of unprecedented scale encouraged millions of marginalarmers and landless people to plant J. curcas (Fairless, 2007; Kantnd Wu, 2011). But the results achieved so far are not encouraging.n India seed production does not reach the expectation. In China,ntil today, the production of biodiesel from J. curcas oil is quite

ow (Fairless, 2007; Kant and Wu, 2011).Nevertheless, according to the current scientific thought, a wise

nd proper J. curcas use at local level, supported by additionaltudies, might be a good solution in terms of energy services

mprovement, environmental problem mitigation, and income-enerating activities creation in developing countries (Achten et al.010; Dyer et al. 2012). Its peculiar characteristics enable an easy

ntegration of J. curcas plantations into the rural economy at village

d Products 42 (2013) 202– 215 203

level (IFAD-FAO, 2010). Community-based initiatives on J. curcasplantation could positively contribute to the rural livelihoods, ifbased on small plantations in marginal lands or on intercroppedagro-forestry systems with the aim at producing oil and by-products (Achten et al., 2008; Kant and Wu, 2011; Dyer et al., 2012).

In this paper, the state-of-the-art of the whole J. curcas chain,from sowing to biodiesel and by-products, is presented. In orderto provide a comprehensive summary of the J. curcas system, allthe available information has been collected from peer-reviewedliterature, conference proceedings, books, and project reports. Themain aim is to compare potentialities and criticalities of J. curcasplantation and productive system, highlighting, for each produc-tive step, the agronomical, management, and environmental issueswhich should be still investigated.

2. J. curcas botany, ecology, and agronomy

2.1. Botanical description

The genus Jatropha belongs to the tribe Joannesieae (orJatropheae) of the subfamily Crotonoideae in the Euphorbiaceaefamily. Although still controversial, J. curcas is probably native oftropical America, with the original area of distribution in Mexicoand in continental Central America (Belize, Costa Rica, El Salvador,Guatemala, Honduras, Nicaragua and Panama) (Maes et al., 2009).From tropical America, J. curcas was probably distributed to Africaand Asia by Portuguese seafarers via Cape Verde Islands and GuineaBissau and, nowadays, it has a pantropical distribution (Achtenet al., 2010a).

J. curcas is a perennial large shrub or small tree, with a lifeexpectancy of up 50 years (Heller, 1996). The plant can reach aheight of 3 m, but under favorable conditions it can grow even upto 5–6 m. J. curcas shows articulated growth, with a morphologicaldiscontinuity at each internode, and its dormancy is induced byrainfall and temperature fluctuations (Heller, 1996). The plantpresents terminal and axillary small buds and branches from theground. Stem is straight, with thin pale-brown bark and numerousscars due to the fallen leaves. Branches are glabrous, stout, andcontain latex (Heller, 1996; Kumar and Sharma, 2008). J. curcasleaves are green to pale-green, 5–7 lobed, smooth, alternate tosub-opposite with a spiral phyllotaxis, and hypoamphistomatic,with length and width of 6–15 cm, petiole of 5–20 cm long, andparacytic (brachyparacytic) stomata (Abdulrahaman and Oladele,2011). In climates characterized by a dry season, it is a deciduousplant and sheds its leaves during the dry season (Kumar andSharma, 2008). J. curcas initially develops a deep taproot and fourmain secondary order roots. These four roots, symmetrically dis-tributed in the horizontal plane, originate at the same depth alongthe main root and have an inclination of −45◦. Adult trees presentfour clearly dominant secondary order roots, with an inclinationof −20◦ and −40◦, and develop a more branched root system,with a dense net of finer horizontal lateral root in the topsoil(Reubens et al., 2011).

J. curcas, a diploid species with 2n = 22 chromosomes, ismonoecious with unisexual male and female flowers on thesame inflorescence. Inflorescences, formed terminally on spe-cific branches, are dichasial cymes and possess main andco-florescences with paracladi. They contain unisexual, occa-sionally hermaphroditic, greenish yellowed flowers (Raju andEzradanam, 2002). Normally, the inflorescences produce a termi-nal individual female flower surrounded by a group of male flowers.

Numerically, 1–5 female flowers and 25–93 male flowers are pro-duced per inflorescence (Raju and Ezradanam, 2002). Male flowershave 10 stamens arranged in 2 distinct whorls in a single col-umn in close proximity to each other in the androecium. Female

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owers, syncarpous with trilocular ovary, have three slender styles,onnate to about two-thirds of their length, and bifurcate stigmasach (Kumar and Sharma, 2008). J. curcas is a protandrous species:he male flowers start to open from the first or second day of thenflorescence life for a period of 8–10 days, with pollen viabilityf 2 days, while the 60% of total female flowers open between thehird and the fifth day, with a life span of about 4 days (Lou et al.,007). The flowering season and the number of flowering events, asell as the male and female flower ratio, are dependent upon tem-erature, available soil moisture, and soil fertility (Kant and Wu,011). Normally, flowering occurs during the wet season (one orwo flowering peaks), but in permanently humid regions, J. curcasowers throughout the year (Achten et al., 2008). The flowers areainly pollinated by insects, especially by honey bees (Divakara

t al., 2010).Fruits (sometimes named capsules) are green-brown ovoid cap-

ules, 2.0–3.5 g weight, 4 cm long, 3 cm diameter, and generallyri-halved, each comprised of one seed (Heller, 1996). The pericarpemains fleshy, indehiscent, and green until the seeds are mature.fter 2–3 months from fruit formation, when fruits are completelyeveloped and reach maturity, the exocarp dries, forming the husksometimes named fruit coat or fruit shell) of the fruit, and its colorhanges from green to yellow, brown, and finally black (Kumar andharma, 2008). The husk opens partly, but seeds do not fall out. In aature fruit, husk is the 30–40% of the total fruit weight and seeds

re the remaining 60–70% (Fig. 1).Seeds, 2–3 per capsule, are black, ellipsoid, triangular-convex,

.5–0.7 g weight, about 2 cm long and 1 cm thick. The 30–40% of theotal seed weight consists of an external brown-black shell (some-imes named hull or seed husk), whereas the remaining 60–70%onsists of kernel, the white oil-containing compact nucleolus ofeed (Fig. 1) (Achten et al., 2008). J. curcas seed contains about0–35% of oil per dry mass, stored at 99% in the kernel (Jongschaapt al., 2007). The seeds of J. curcas contain also a wide range of con-tituents toxic to humans and animals (Kumar and Sharma, 2008).horbol esters have been identified as the main agent responsi-le for J. curcas toxicity (Makkar et al., 1997). Phorbol esters areetracyclic diterpenoid able to interact with protein kinase C affect-ng the activities of several enzymes, protein biosynthesis, DNA,olyamines, cell differentiation processes, and gene expressionGoel et al., 2007). Edible/non-toxic genotypes, characterized byree or low phorbol ester seeds, have been found in Mexico (Bashat al., 2009). The phytotoxin (toxalbumin) curcin, a ribosome-nactivating protein similar to ricin (phytotoxin of Ricinusummunis L.) isolated from J. curcas seed, is able to inhibit proteinynthesis (Lin et al., 2003). Further toxic components include phy-ates, saponins, and trypsine inhibitor (Gübitz et al., 1999). Specificomposition of J. curcas components is reported in Table 1.

.2. Ecology

J. curcas is a drought avoidant, stem succulent plant. As do othertem succulent species with green stems, J. curcas probably has no

pure C3-metabolism, but rather a CAM-metabolism in the suc-ulent stem with leaves shifting from C3-metabolism to the moreater-efficient CAM-metabolism under drought (Maes et al., 2009).nyway the metabolism of J. curcas deserves further attention.

It grows in tropical and sub tropical regions, with cultiva-ion limits at 30◦N and 35◦S (Heller, 1996). Its high ecologicaldaptability allows J. curcas to grow in a wide range of climatic con-itions from semiarid to humid (annual rainfall varying from 300o 3000 mm). Anyway, it does not naturally occur in regions with

nnual rainfall less than 950 mm and more humid environmentalonditions result in a higher productivity (Maes et al., 2009a; FACT,010). Suitable conditions were found with annual precipitationbove 600–900 mm, with an optimum at 1500 mm (Trabucco et al.,

d Products 42 (2013) 202– 215

2010). J. curcas requires mean annual temperatures between 18 ◦Cand 28 ◦C (with optimal values around 26–27 ◦C), average mini-mum temperatures above 8–9 ◦C, indicating a clear lack of toleranceto frost, and average maximum temperatures between 35 ◦C and45 ◦C (Trabucco et al., 2010). The plant is not sensitive to day length(Achten et al., 2008).

J. curcas is able to grow in a wide range of soil types, rangingfrom alluvial soil to red lateritic soil, even on gravelly, sandy, andsaline soils (Ye et al., 2009). Neutral (pH 6.0–8.0), well-drained, andareated soils are preferred, whereas soils with risk of ephemeralwater logging, such as Vertisols or other heavy clay soils, are notsuitable (Achten et al., 2008).

J. curcas strength as a crop derives from its ability to be welladapted to poor quality soils, in terms of structure and nutrient con-tent. However, soil properties have an important effect on J. curcasproductivity, and a poor nutrient level leads to an increase of seeddevelopment failure (Openshaw, 2000). While there is no root asso-ciations with (nitrogen fixing) Rhizobium, arbuscular mycorrhizalfungal (AMF) assisting with the uptake of phosphorus and micro-elements were found on the root system (Achten et al., 2008). AMFinoculated J. curcas plants showed an increase of 30% in biomassand seed production already in 2 years-old plants (Achten et al.,2008). J. curcas is well colonized by AMF across a wide ranges ofsoils condition (from acidic to calcareous, low to moderate organicmatter, and low to high available phosphate), making J. curcas agood potential crop in marginal land plantation where phosphate islimiting (Gour, 2006). On J. curcas cultivated soils positive changesin terms of diversity and density in the composition of soil AMFcommunity has been detected (Charoenpakdee et al., 2010). Fur-ther research is required to identify effective AMF for J. curcas whichcan be used in inoculation programs with the aim at restoring AMFdiversity in marginal lands.

Being an exotic species in most of the actual growing areas,such as Africa and Asia, J. curcas it could potentially have a neg-ative impact on biodiversity. However, its potential impact largelydepends on the plantation system and land use. In J. curcas inten-sive monoculture plantation or in transformed natural systems,such as cleared dry land forests, the impact on local biodiversity canbe particularly severe. In live-fencing or intercropping and agro-forestry system, J. curcas might not have a significant impact. Onthe contrary, when J. curcas is used in reclaiming marginal lands,local biodiversity could be even restored (Sahoo et al., 2009).

2.3. Agronomic practices

J. curcas is still a (semi-)wild undomesticated plant. Its basicagronomic properties are not thoroughly understood, the grow-ing and management practices are poorly documented, and theenvironmental effects have not been investigated yet. J. curcasshows considerable performance variability, which makes seedyield poorly predictable and the J. curcas cultivation a riskybusiness (Behera et al., 2010; Achten et al., 2010a). In this sec-tion, the most common agronomic practices used so far aredescribed.

J. curcas can be propagated by vegetative and generative meth-ods: (i) direct seeding in the field, (ii) pre-cultivation of seedlings(raised in nursery polybags or seedbed), and (iii) planting of cut-tings (directly planted in the field or raised in nursery polybags orseedbed) (Heller, 1996). Description, advantages and disadvantagesof the three methods are reported in Table 2.

The selection of planting material is still a critical step,

and planned crop improvement programs have globally lacked(Divakara et al., 2010). Improved varieties with desirable traitsfor specific growing conditions are not available yet and thevarieties relative performances are still unknown (Behera et al.,

N. Contran et al. / Industrial Crops and Products 42 (2013) 202– 215 205

curcas

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010). At the moment, the most common practice is to uselanting material obtained from the best performing prove-ance available at local level (Achten et al., 2008). Promisingly,

everal germplasm collection and breeding programs are cur-ently ongoing and J. curcas seems to be suitable for quicknd efficient domestication if compared to other woody species

able 1A) Energy values, dry matter and nutrient compositions of J. curcas components. Values aKumar and Sharma, 2008).

A Calorific value(MJ kg−1)

Dry matter(%)b

Moisture(%)b

Crude fat(%)c

Wood 15.5 85 15 –

Leaf – – – –

Root – – – –

Fruit 20–25 77–92 8–23 –

Husk 10–11 15–11 85–89 –

Seed 20–25 93–97 3–7 33.6–37

Shell 17–20 89–90 10–44 0.5–1.4

Kernel 29–31 88–97 3–12 47.3–74

Crude Oil 30–46 95 5 45–55

Seed cake 18–25 – 0–5 1–1.5

B Chemical composition

Bark �-Sitosterol, �-amyrin, and taraxerol.Latex Curcacycline A, a cyclic octapeptide, curcain.Leaf Cyclic triterpenes stigmasterol, flavaonoids apigenin,

flavonoidal glycoside.Root Diterpenoids jatrophol and jatropholone A and B, �-si

curculathyranes A and B, curcusones A-D, coumarin toSeed Phorol esters, curcin, a lectin, esterases, lipases, phyta

a Source: Openshaw (2000), Akintayo (2004), Martinez-Herrera et al. (2006), Jongschaaübitz et al. (1999), and Islam et al. (2011).b Given percentage are % per wet matter weight.c Given percentage are % per dry matter weight.

system.

(Achten et al., 2010a; Divakara et al., 2010; Vaknin et al.,2011).

For oil production purposes, field preparation mainly consists

of land clearing and ploughing. In case of transplantation of pre-cultivated plant, hole digging (30–45 cm wide and deep) is alsorequired, possibly refilled with organic matter (IFAD-FAO, 2010).

re the maximum range available in literature.a (B) Chemicals isolated from J. curcas

Protein(%)c

Crude fiber(%)c

Nitrogen(%)c

Phosphorus(%)c

Potassium(%)c

– – 3.34 0.09 2.87– – 1.23–6.40 0.15–0.34 0.90–3.77– – 2.16 0.08 2.18– – 2.15 0.05 0.73– – 0.19–0.86 0.04–0.05 0.73–4.2338.38 10.6–22.88 – 0.31 –3.7–7.8 28.8–89.4 0.19–0.7 0.01–0.04 0.3–1.5814.1–27.2 1.9–27.2 1.96–4.39 0.37–1.10 0.42–1.2525–35 3–10 – – –56.4–63.8 8.1–9.1 3.82–6.40 0.9–2.9 0.95–1.75

vitexin, isovitexin, atriterpene alcohol dimmer, and two

tosterol and its �-d-glucoside, marmesin, propacin,mentin, coumarino-lignan jatrophin, and taraxerol.

tes, saponins, a trypsine inhibitor.

p et al. (2007), Achten et al. (2008), Kumar and Sharma (2008), Reena et al. (2008),

206 N. Contran et al. / Industrial Crops and Products 42 (2013) 202– 215

Table 2Description, advantages and disadvantages of the propagation methods of J. curcas (Achten et al., 2008; Kumar and Sharma, 2008; FACT, 2010; Severino et al., 2010).

Method Description Advantage Disadvantage

Direct seeding Dry seeds for at least one monthPlant seeds at 4–6 cm deep, with two perstation, and latter thin one

Cheap methodProduce plant with a good taprootdevelopment

Low survival ratePoor uniformity of growthVariable productivity of the progenyWeeding requirementTiming dependent for success (at thebeginning of the rainy season)

Seedlings Dry seeds for at least one monthFill polybags with a high concentration oforganic materiala

Sown seeds in polybags 3 months before therainy seasonWatering until transplantingTransplant seedlings in 20 cm holes

Good germination survivalUniform plant growth through control overmoisture, shade, soil, weeds, pests, anddiseases

High costVariable productivity of the progenyInitially high water consumptionBags can interfere with the formation of anormal root system

Cuttings Make cuttings at least 30 cm from the thickestbranches at the base of the plantPlace directly in wet soil leaving 15 cm or moreof branch above the soilKeep soil watered

Genetic uniformityRapid establishmentEarly yield

Cuttings do not develop a true taproot: lowlongevity and low drought and diseaseresistanceInitially high water consumption

re.

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The first shoots appear after 3–4 weeks

a 1:1 sandy loam soil–compost; 1:1:2 sand–soil–compost; 1:1:1 sand–soil–manu

n optimal J. curcas planting density is still unknown and densityanges from 1100 to 2500 plants ha−1. Planting distance shoulde based on the environment and plantation purpose. In semi-rid and low input system, wider spacing such as 3 m × 2 m (1667lant ha−1), 3 m × 2.5 m (1333 plant ha−1), and 3 m × 3 m (1111lant ha−1) are common practices (IFAD-FAO, 2010). Since seedield per tree significantly increases with wider spacing, whereaseed yield per hectare decreases, the most currently used practice totabilize the yield is to start with a densely spaced plantation andradually remove the rows according to the plant performancesBehera et al., 2010). When J. curcas is planted for live-fencing,

dense biomass with close spacing of around 50 cm and over iseeded (Behera et al., 2010).

The standard agronomic practice involves timely fertilization,eeding, and pruning. Although J. curcas is adapted to low fertility

ites and alkaline soils, fertilizer application together with optimalrrigation (or adequate rainfall) are required in order to increaseeed and oil yield (IFAD-FAO, 2010). On the contrary, high levelsf fertilizer application and excessive irrigation can induce highotal biomass production but low seed production (Achten et al.,008). Unfortunately, the input levels required to optimize the yieldt different conditions have to be quantified yet. No quantitativeata on water requirement and water use efficiency of J. curcasre available at present (Maes et al., 2009). In general, a higherield is obtained by using fertilizers containing small amounts ofalcium, magnesium, and sulfur. Application of super phosphater NPK fertilizer (40:100:40 kg/ha NPK at 6 monthly intervals) iseported to increase the seed yield (Gour, 2006). The optimumpplication levels of inorganic N and P fertilizers are observed to beariable according to the plantation age (Achten et al., 2008). Fer-ilization should be applied at least to compensate the nutrient netemoval from the soil due to fruit production. The net removal cane estimated from the fruit nutrient composition in 14.3–34.3 kg, 0.7–7.0 kg P and 14.3–31.6 kg K ha−1 for the fruit equivalent of

t of dry seed ha−1 (Jongschaap et al., 2007). Further studies on. curcas management practices should be carried out, includingetailed investigations on J. curcas fertilizer and soil requirementsOpenshaw, 2000).

Regular weeding operations should free the field from com-

etitive weeds, leaving the uprooted weeds on the field as mulchAchten et al., 2008). Canopy management and periodical pruning,arried out depending on the vegetative growth of the plant, play anmportant role in improving the production of more branches and

of abundant and healthy inflorescences, thus eventually enhanc-ing good fruit setting and consequently seed yield (Gour, 2006).Pruning should be done after the trees have shed their leaves, inthe dry or winter period, and should result in a lower and widertree shape, able to induce earlier seed production and facilitatemanual harvesting (IFAD-FAO, 2010). At the age of 6 months, theterminal shoots should be pinched at 30–45 cm height, in order tomaximize growth rate and to optimize the number of primary andsecondary branches (Behera et al., 2010). At the end of the first year,the secondary and tertiary branches should be pinched or prunedto induce a minimum of 25 branches. During the second year, min-imum 35–40 branches should be induced and side branches shouldbe pruned up to two-thirds of the top portion, retaining one-thirdof the branches on the plant (Gour, 2006).

J. curcas, being perennial and having little negative allelopathiceffect on other plants, can be intercropped with seasonal shade-tolerant crops or other fruit plantations (Gour, 2006). Agro-forestrysystems with J. curcas would provide alternative options for the uti-lization of marginal land. Intercropping systems with leguminouscould result in soil fertility improvement, by increasing organicmatter, allowing an efficient nutrient circulation, reducing soil ero-sion and run off and improving the soil physical conditions (Gour,2006).

Because of its insecticidal and toxic characteristics, diseases andpests do not seem to significant threat J. curcas in such extent tocause economic damage. However, diseases and pests incidenceis widely reported under continuous monoculture plantation, sug-gesting that J. curcas susceptibility may depend on managementintensity (IFAD-FAO, 2010). J. curcas is attacked by several impor-tant diseases and pests, which normally damage Euphorbiaceaeplants (Table 3). Mostly occurred diseases are spots and rust causedby fungi and bacteria, while fruit sucking, premature fruit abortionand malformed seeds are caused by arthropods. Observed diseases,such as spots or root rot, may be controlled with a combination ofcultural techniques (e.g. avoid water logging condition) and fungi-cides (IFAD-FAO, 2010). Biological pest control measures could bepossible actions against J. curcas pests. For example, in Nicaragua,Pseudotelenomus pachycor have been found to be an effective eggparasitoids of Pachycoris klugii (IFAD-FAO, 2010) or, in India, the

Tacinid spp. and Brancon hebert are parasitoids of Pempelia moros-alis (Shanker and Dhyani, 2006). Attention to increasing resistanceto pests and diseases should be given in J. curcas varietal improve-ment programs. Furthermore, Jatropha multifida L. is a possible

N. Contran et al. / Industrial Crops and Products 42 (2013) 202– 215 207

Table 3Most common J. curcas diseases and pests (Shanker and Dhyani, 2006; IFAD-FAO, 2010; FACT, 2010; Kumar et al., 2011; Sarmento et al., 2011; Srinivasa et al., 2011).

Disease Symptom Kingdom Family

Alternaria ricini Drop of bud and flower Fungi PleosporaceaeBotryosphaeria dothidea Black root rot Fungi BotryosphaeriaceaeBotrytis ricini Fruit blackish spots Fungi SclerotinicaeaeCercospera spp. Leaf spot Fungi MycosphaerellaceaeColletotrichum gloeosporioides Leaf spot Fungi GlomerellaceaeFusarium spp. Leaf spots and root rot Fungi NectriaceaeMelampsora ricini Rust diseases Fungi MelampsoraceaePhakopsora jatrophicola Rust diseases Fungi PleosporaceaePhytophthora spp. Root rot Fungi PythiaceaeRhizoctonia bataticola Collar rot Fungi EratobasidiaceaeXanthomonas pocks Leaf black spots Bacteria XanthomonadaceaeXanthomonas ricinocota Leaf black spots Bacteria Xanthomonadaceae

Pest Common name Order Family

Achaea janata Semi-looper Lepidoptera NoctuidaeAgonosoma trilineatum Seed feeding bug Hemiptera ScutelleridaeAphthona spp. Flea beetle Coleoptera ChrysomelidaeHypselonotus intermedius Distant Flower feeding true bug Hemiptera CoreidaeIndarbela quadrinotata Bark-eating caterpillar borer Lepidoptera CossidaeLeptoglossus zonatus Fruit feeding leaf-footed bug Hemiptera CoreidaeOxycetonia versicolor Flower beetle Coleoptera CetoniidaePachycoris klugii Burmeister Fruit feeding shield-backed true bug Hemiptera ScutelleridaePempelia morosalis Moth Lepidoptera PyralidaePolyphagotarsonemus latus Broad mite Acari Tarsonemidae

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Scutellera nobilis Sap sucking scutellarid bStomphastis (acrocercops) thraustica Moth blister minerTetranychus bastosi Red spider mite

ost of the cassava (Manihot esculenta) super-elongation diseaseSphaceloma manihoticola) and of the African cassava mosaic virus.hus, also J. curcas and M. esculenta should not be grown in associ-tion (Achten et al., 2008).

The harvesting of J. curcas fruits is an intensive labor. Althoughruit maturity is reached 90 days after flowering, fruits do not

ature all at the same moment, implying manual harvests at regu-ar (daily or weekly) intervals (Kumar and Sharma, 2008). Anyway,

prolonged harvesting period instead of a single harvesting day,enerally undertaken by man, may promote the employment ofural women in the J. curcas plantation.

Data of manual daily harvesting rates show a large variationmong the countries, running from 16 to 144 kg of dry seed per dayFACT, 2010). The length of the harvest period depends on the cli-

atic conditions: in semi-arid regions, the harvest is spread over aeriod of 2 months; in permanent humid situations weekly harvestan be necessary throughout the year (Achten et al., 2008). The J.urcas yield is still unknown, and a wide yield range is reported initerature: annual dry seed production can range from about 0.4 to 12 t ha−1 (Fig. 1) (Achten et al., 2008; Parawira, 2010), equivalento 90–900 fruits per tree or to 0.2–2 kg of dry seed per tree (Fig. 1).. curcas yield depends on site characteristics (rainfall, soil typend soil fertility), genetics, plant age, and management practicespropagation method, spacing, pruning, fertilizing, irrigation, etc.).dditionally, since it is still a wild plant and a systematic selectionnd improvement of suitable germplasm has not been performedet, J. curcas exhibits a high variability in yield among individualrees.

Regarding the seed storage, seeds should be stored in dry andentilated conditions, where they can maintain viability and oilontent for 7–8 months. The storage of seeds at low temperaturellows them to extend the viability and effective emergence (Gour,006).

. J. curcas uses and products

J. curcas is a multipurpose tree with several attributes and mul-iple uses (Fig. 1).

Hemiptera ScutelleridaeLepidoptera GracillariidaeAcari Tetranychidae

3.1. Environmental problem mitigation

J. curcas is able to generate environmental benefits, such asimproving soil quality, preventing soil erosion, and promotingmarginal land reclamation and soil remediation (Openshaw, 2000).J. curcas positive effects on soil quality are related both to soilstructure improvement and an increment of the organic mattercontent. The action of the roots allows the increment of the aggre-gate average diameter and the number of macro-aggregates inthe first 10 cm of soil (Ogunwole et al., 2008). The developmentof a deep taproot, functioning as an efficient nutrient circulationpump, permits to extract minerals and nutrients leached down, andreleases them to the surface through the leaf or fruit shed, formingmulch nearby the base of the plant. The organic matter from shedleaves enhances earthworm activity around the root-zone of theplant, improving the fertility of the soil (Kumar and Sharma, 2008).

J. curcas has proven to be effective in reducing the soil erosionby rainwater (Behera et al., 2010). This is due to the developmentof a dense net of fine roots near the surface, which binds the soil,fixing small earth or stone dams and preserves the soil from beingwashed out by heavy rains (Reubens et al., 2011). Moreover, nearsurface roots reduce water run-off, allowing a better drainage, andboosting water harvesting. The symmetrical structure of the coarseroot system plays an important role also for slope stabilization andcontrol of incisive erosion processes, such as rill and gully ero-sion (Reubens et al., 2011). J. curcas hedges are also suitable forpartially preventing wind erosion and shifting of sand dunes, byreducing wind velocity and binding the soil with their surface roots(Reubens et al., 2011). This positive effect is due also to the fastaboveground development and the planting method (dense hedgeplanting). Unfortunately, these wind anti-erosion effects are lim-ited by dry season leaf drop, causing less protection when winderosion is often highest (IFAD-FAO, 2010).

J. curcas ability to grow on poor quality soil, combined with

its capacity to improve soil physical conditions and reduce soilerosion, makes this tree an excellent biological system for the recla-mation of degraded soil. Since different definitions of the landcategories lead to possible misunderstanding, according to the land

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ategory terminology proposed by Wiegmann et al. (2008), in thiseview J. curcas is considered able to reclaim abandoned farmlanddefined as land previously used for agriculture or pasture, buthich has been abandoned and not converted to forest or urban

reas, for economical or environmental reason) and/or marginaland (defined as an area where cost-effective production is notossible under given side conditions, cultivation techniques, agri-ulture policies as well as macro-economic and legal conditions).n the contrary, wasteland (defined as land characterized by natu-

al, physical, and biological conditions which are per se unfavorableor land-associated human activities, e.g. deserts, high mountainones, or salt flats) cannot be considered suitable for J. curcaslantations.

J. curcas promotes also soil remediation, due to its capabilityo survive in phytotoxic environments and to grow on soils withigh heavy metal concentration. Kumar et al. (2008) have shownhat heavy metal contaminated soils could be restored by using J.urcas plantation coupled with a combination of industrial organicastes and biofertilizer (e.g. Azotobacter).

.2. Live-fencing

J. curcas is an excellent hedging plant, and it is often plantedo protect gardens and crop fields from livestock, to mark home-tead boundaries, to create fire barrier, and to prevent soil windrosion. J. curcas protection effects can be exploited only after 3–4onths from germination, when its mature leaves become unpalat-

ble to cattle, as sheep and goat. When planted very close together,. curcas plants create a barrier that is impenetrable even by chick-ns. Being a stem succulent plant, J. curcas could be planted as are barrier, since the moisture content of its stem and leaves iselatively high, imparting strong fire tolerance (Ye et al., 2009).nfortunately, seed-oil production is not compatible with hedge

unction: the dense biomass and close planting spaces of J. cur-as live-fencings do not allow the high seed yields required by oilroduction plantations (Behera et al., 2010).

.3. Medical use

J. curcas tree is widely used as traditional medicinal for thereatment of various human and veterinary ailments, thank to itseculiar chemical composition (Table 1) (Heller, 1996). However,ost of J. curcas traditional medicinal properties need to be inves-

igated in depth and to be subjected to medical and toxicologicalnalyses (Reena et al., 2008).

Preparation of all parts of the plant (leaves, bark, latex, rootsnd seeds), fresh or as a decoction, have purgative and laxativeffects (Islam et al., 2011). J. curcas leaves can be used againstalaria, rheumatic and muscular pains (Gübitz et al., 1999; Reena

t al., 2008). Antibiotic activity of leaf alcohol extracts have beenbserved against organisms including Staphylococcus aureus andscherichia coli (Ye et al., 2009). J. curcas latex, the sap flowing fromhe stem, is used to control the bleeding of wounds, thank to itsoagulation effects on blood plasma (Islam et al., 2011). As leafxtract, latex can be used against S. aureus and E. coli (Ye et al.,009), and probably the latex alkaloids present anti-cancerousroperties (Reena et al., 2008). It is also used as a disinfectant inouth infections in children and externally against skin diseases,

iles and sores among the domestic livestock (Kumar and Sharma,008). J. curcas root extracts help to check bleeding from gums, androbably roots contain an antidote against snake venom (Heller,

996). J. curcas oil can be applied to treat eczema and skin dis-ases and to soothe rheumatic pains (Heller, 1996). Seed extractsre also used as contraceptive or to induce abortion (Gübitz et al.,999).

d Products 42 (2013) 202– 215

3.4. Food

J. curcas is not an edible tree. Seeds are toxic and poisoning tohumans, due to the presence of anti-nutritional (trypsin inhibitors,curcin, tannins, saponins, and phytates) and toxic factors (phor-bol esters) (Table 1). Nowadays, only the seeds of the Mexicannon-toxic variety, characterized by free or low phorbol ester con-tent, can be used for human consumption after roasting (Kumarand Sharma, 2008). Studies and trials on propagation and cultiva-tion of the non-toxic variety have been established, but additionalresearch is needed in order to avoid clinical problems caused byanti-nutritional components. Furthermore, the non-toxic varietyof J. curcas could be also a potential source of oil for human con-sumption. When propagated by generative methods, young leavescan be edible for the first 3 months, since the toxic material has notbeen developed yet (Islam et al., 2011).

3.5. Combustible fuel and charcoal

The several and high-value marketing uses and by-products ofJ. curcas discourage its use as fuelwood. J. curcas wood is a lightwood, remains green for a long time, and burns too quickly, mak-ing it not popular as fuelwood (Islam et al., 2011). Furthermore,even the value of J. curcas charcoal is not considered economicallyimportant, since in simple charcoal making processes the 70–80%of wood energy is lost (Kumar and Sharma, 2008).

3.6. Seed oil, seed cake and husk

3.6.1. Oil extraction and by-productsJ. curcas seeds contain about 30–35% of oil per seed dry mass,

which can be relative easily expelled or extracted (Jongschaap et al.,2007). The production of oil from J. curcas seeds requires sev-eral steps: (i) dehusking process, to separate seeds from husk, (ii)dehulling process, to separate kernel from shell, (iii) oil extractionprocess, to produce oil and seed cake as by-product, and (iv) oilcleaning process, to transform crude oil, with impurities, into pureoil (Fig. 2).

Prior to oil extraction, the seeds have to be separated by thehusks manually, opening them by hand (1.8–2 kg h−1), or througha decorticator (sometimes named dehusker or sheller) machine,which consumes about 20–40 l of J. curcas oil to power the engineand with an average capacity of about 200–300 kg h−1, depend-ing on the equipment technical characteristics. Afterwards, seedscould be dehulled, separating kernels from the shells. This pro-cess can be performed manually, by using stone or wooden plank,and then winnowed (26–30 kg h−1), or through a dehuller (some-times named craker or winnower) machine (average capacity about170 kg h−1). The importance of the dehulling process depends onthe adopted oil extraction method and is not always mandatory.Finally, seeds (or kernel) have to be dried in an oven (105 ◦C) or besolar heated for at least 3 weeks (FACT, 2010).

Nowadays, two methods have been identified for the extractionof seed-oil: (i) mechanical extraction and (ii) chemical extrac-tion; but the possibilities, procedures, and means are evolvingrapidly (Achten et al., 2008). The mechanical extraction is per-formed using presses, such as manual ram press (e.g. Yenga orBielenberg ram press, hand-operated expeller for small-scale use,1–10 kg seed h−1), manual screw press, or engine driver screw press(or expeller, e.g. Sundhara expeller, Sayari expeller, or Chineseexpeller). In a screw press, an endless screw rotates in a metal cylin-der and continuously kneads and transports seeds from an entry

funnel into a nozzle under pressure. Over the length of the screw,the oil runs out from holes placed on the side of the metal cylin-der into a reservoir (FACT, 2010). With a engine driver screw press,the oil yield obtained from 1000 kg of dry seeds could be around

N. Contran et al. / Industrial Crops an

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pfEi(fifitp

Fig. 2. Processes for J. curcas oil and biodiesel production.

20–260 l in 6–8 working hours, considering that the oil extractionfficiency of the engine expeller is around 75–80% and that about0% of the produced oil is required to power the press (IFAD-FAO,010). Mechanical extraction can be performed on either wholeeeds or sole kernels or a mix of both, but the most common prac-ice is to use the whole seeds (FACT, 2010). Chemical extractiononsists in solid-liquid extraction, which involves the transfer of aoluble fraction from a solid material to a liquid solvent (with orithout enzyme). The main chemical extraction methods studied

nd used on J. curcas seeds are: (i) n-hexane oil extraction (95%il yield), (ii) aqueous oil extraction (40% oil yield), and (iii) aque-us enzymatic (hemicellulase, cellulase, or alkaline protease) oilxtraction (70–80% oil yield) (Achten et al., 2008). Higher yield andess turbid oil than mechanical extraction are the advantages ofhe solvent extraction. The solvent extraction is profitable only at

large-scale production, higher than 50 t of oil per day, and couldave a huge negative environmental impact (Adriaans, 2006). Addi-ionally, chemical extraction has to be performed on sole kernelsAchten et al., 2008).

The crude J. curcas oil, produced directly by the expeller afterressing, contains many impurities: solid or dust particles, water,ree fatty acid, phosphor, and pro-oxidant metals (e.g. copper, iron).ven if the cleaning of crude oil depends on oil use, removal of thesempurities is required to prevent oil deterioration during storageFig. 2). While the quality requirements are not stringent for lampuel or soap-making, prior to use the crude oil in a diesel engine,

t should be free of all the particles larger than 5 �m to avoid fuellters clogging (FACT, 2010). Moreover, the free fatty acids, mois-ure content, and phosphor have a negative impact in the biodieselroduction from J. curcas oil (see Section 3.6.2.5). Dust and solid

d Products 42 (2013) 202– 215 209

particles can be removed by sedimentation, filtration, or centrifug-ing methods (Koh and Ghazi, 2011). Sedimentation, recommendedfor small processes, is the simplest and cheapest way of cleaningby exploiting the earth’s gravity: solids settle at the bottom of atank. The filtration is carried out in a membrane, which blocks anyparticle bigger than its pore size. Several methods of filtration arereported in literature, such as gravity, band or bag filters, filter press,or pressure leaf filters (FACT, 2010). Free fatty acid content (FFA) ofcrude J. curcas oil can be reduced with several methods: steam dis-tillation, extraction by alcohol, and esterification by acid catalysts(see Section 3.6.2.5) (Leung et al., 2010).

Crude J. curcas oil contains approximately 45–55% of crude fat(Table 1) (Martinez-Herrera et al., 2006). The 14% of crude fat arefree fatty acids (Koh and Ghazi, 2011), whereas more than 60% ofcrude fat are triglycerides, 70% of which are unsaturated fatty acidand 30% are saturated fatty acids. The 40% of unsaturated fatty acidsis oleic acid (18:1) and 35% is linoleic acid (18:2), while 12% ofsaturated fatty acids is palmitic acid (16:0) and 3% is stearic acid(18:0) (Martinez-Herrera et al., 2006). Similar to the seed composi-tion, J. curcas oil contains several toxic components, such as phorbolesters, curcains, and trypsin inhibitors, which, however, do not givepollution when burnt (Parawira, 2010).

J. curcas oil quality can deteriorate if improperly handed andstored, due to several chemical reactions, such as hydrolyzes, poly-merization, and oxidation (Parawira, 2010). Oil should be storedin a cool (less than 30 ◦C) and dry room, avoiding temperaturevariations and water condensation, exposure to light and air, andpotential volatile gaseous substances (like petrol). The oil containershould preferably be hermetic and filled up to the maximum, inorder to prevent condensation and thereby water in the oil (FACT,2010).

The wide range of J. curcas crude oil characteristics (Table 4)suggests that oil quality is dependent on the interaction betweenplant genotype and environment and on oil extraction method effi-ciency (Achten et al., 2008). Further research is needed and projectdevelopers and decision makers should be aware of this wide vari-ability.

The extraction of oil from J. curcas seed generates also importantby-products: fruit husks and shells derived by the dehusking anddehulling processes, while about 50–70% of the original seed weightremains as de-oiled seed cake, which can be further pressed to formpress cake pellets (Figs. 1 and 2) (IFAD-FAO, 2010; Devappa et al.,2010). Components of husk, shell, and seed cake are reported inTable 1.

The amount of oil kept in the seed cake depends on the extrac-tion process (higher in the oil mechanical extraction methods thanin chemical extraction). Based on the extraction efficiencies dis-cussed above, the seed cake could contain up to 9–12% oil by weight,which increases its gross energy value (Achten et al., 2008). Similarto the oil composition, seed cake contains several toxic componentsand cannot be used as animal feed if not detoxified.

3.6.2. Products and uses of seed oil3.6.2.1. Cooking and lighting fuel. J. curcas oil can be used as cookingand lighting fuel, instead of traditional biomass (firewood, char-coal, kerosene or petrol). The advantages of using J. curcas oil as fuelare easily identifiable: health benefits from reducing smoke inhala-tions, and environmental benefits from avoiding forest cover lossand decreasing greenhouse gas emissions. Additionally, benefitscould also result in saving time, enabling people (usually women)involved in the firewood or charcoal collection to dedicate moretime to other activities.

Unfortunately, the high viscosity of J. curcas oil does not allowits direct use in conventional kerosene stoves or lamps and needsspecial designed equipment. In order to use J. curcas oil as cook-ing fuel, two basic stoves have been designed (Henning, 2009). The

210 N. Contran et al. / Industrial Crops and Products 42 (2013) 202– 215

Table 4Characteristics of the crude J. curcas oil and J. curcas methyl ester.

Characteristic J. curcas oila J. curcas methyl estera

Calorific value (MJ kg−1) 37.83–42.05 39.65–41.63Density at 15 ◦C (g cm−3) 0.92–0.95 0.86–0.88Viscosity at 30 ◦C (cSt) 37.0–54.8 4.8–5.6Specific gravity (g cm−3) 0.860–0.933 0.86–0.88Cetane value 38–51 60.74–63.27Saponification number (mg g−1) 102.9–209.0 –Pour point (◦C) −3 −6 to 2Cloud point (◦C) 2 –Flash point (◦C) 201–240 170–192

en et a

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Acid value (mg KOH−1 g−1) 0.92–6.16

a Values are the maximum range available in literature (Gübitz et al., 1999; Acht

ressure stove, designed by the University of Hohenheim, emits oilnto burner under air pressure, but requires pre-heating with alco-ol and frequent cleanings to remove carbon deposits. The wicktove works through the rising up of oil to the burner by capil-ary action. The main problem is that the oil does not easily rise uphe wick, leaving carbon deposits on the wick as it burns (Henning,009). The problem of J. curcas oil’s high viscosity and poor capillaryction also applies to lamp design. One solution could be the utiliza-ion of a floating wick lamp (such as the Binga oil lamp), with a wickept as short as possible and a flame just above the oil. This lampequires periodic cleaning of the wick to remove carbon depositsnd the oil level has to be maintained constant (Islam et al., 2011).

.6.2.2. Bio-pesticides. J. curcas oil or oil extracts can be used asio-pesticides, due to the presence of insecticidal, molluscicidal,ungicidal, and nematicidal agents (Kumar and Sharma, 2008).owever, these potential uses still need to be commercialized.urther and more detailed studies should be performed to bet-er understand environmental risks, extraction methods, extractsroperties, and optimal concentrations which are at the same timeffective on pathogens and pests but non-toxic for beneficial pop-lations and humans. Oil, extracts, and phorbol esters, used asatural crop pesticides in controlling insect pathogens, could be aromising alternative to hazardous chemicals (Gübitz et al., 1999).dditionally, in contrast to spraying with chemicals, treatmentsith J. curcas oil and extracts seem to not affect the population

f beneficial arthropods (Heller, 1996). J. curcas oil extracts showotential in controlling several insect pests and present mollusci-idal activities against hosts of human diseases (Table 5). Finally,ecent works show that water crude extracts from J. curcas shell,ranch or leaf have an herbicidal activity (Li et al., 2009).

.6.2.3. Direct use in diesel engine. Pure J. curcas oil may be usedirectly in some diesel engines. However, direct use of vegetableils into traditional engines is generally unsatisfactory and diffi-ult because of the high viscosity, acid composition, and high FFAontent. Secondary disadvantages are the gum formation due toxidation, polymerization during storage and combustion, oil ringticking, and carbon deposits (Parawira, 2010).

Basically, there are three types of options for using J. curcasil in diesel engines: (i) indirect-injection engines; (ii) two-tankystem, and (iii) single-tank system (FACT, 2010). Some olderesign indirect-injection diesel engines, such as the Lister singleylinder engines, can use J. curcas oil without any change otherhan an appropriate fuel filter. Additionally, in order to avoid filterlocked, the fuel filter has to be changed regularly once a year. Inhe two-tank system, the power unit is divided into two separated

anks, one for oil and one for diesel. In this system, in order to avoidhe problem of cold starting with the viscous J. curcas oil, the engineurns on and off using diesel or biodiesel and it is then switched,

anually or automatically, to oil when the operating temperature

0.06–0.5

l., 2008; Koh and Ghazi, 2011).

is reached. The single-tank system uses fuel injectors capable ofdelivering higher pressures to overcome the high oil viscosity,stronger glow plugs, a fuel pre-heater and a modified fuel filter(FACT, 2010). Nowadays, several engines which use these two-tankand single technologies are available on the market, but the long-term viability of these systems in terms of engine performanceand reliability remains to be fully assessed (FACT, 2010).

3.6.2.4. Soap. The local production of soap is one of the most eco-nomically attractive uses of J. curcas oil, due to its easy productiontechnology and its medicinal use in treating skin ailments (IFAD-FAO, 2010). Soap is made by cooking 1 l of J. curcas oil with a solutionof sodium hydroxide (150 g of sodium hydroxide with 0.750 l ofwater) and leaving the mixture hardening into a mold overnight.This method allows the production of more than 1 kg of a soft,durable soap from 1 l of oil in two working days. This simple pro-cess allows to integrate the soap making into a viable small-scalerural enterprise, well adapted to household or small-scale indus-trial activity (Islam et al., 2011). Anyway, the locally produced J.curcas soap has limited commercial potential, since its lower qualityin comparison with imported soap (IFAD-FAO, 2010).

Finally, J. curcas soap can be produced also from glycerin, a by-product of the transesterification process in biodiesel production(see Section 3.6.2.5) (Kumar and Sharma, 2008).

3.6.2.5. Biodiesel. J. curcas oil is a promising renewable feedstockfor biodiesel production. High yield and relative low cost methodsfor oil-biodiesel conversion have already been developed. Pure J.curcas oil can be chemically modified into biodiesel through fourprimary methods: (i) blending, (ii) microemulsion, (iii) pyrolysis,and (iv) transesterification (Fig. 2) (Koh and Ghazi, 2011). Blend-ing of crude oil consist in diluting crude oil with diesel fuel toreduce the oil viscosity. Microemulsion of J. curcas oil is a colloidalisotropic equilibrium dispersion of three-components fluid: an oilphase (complex mixture of hydrocarbons and olefins), an aqueousphase (containing salts) and a surfactant (higher alcohols, such asbutanol, hexanol or octanol). Microemulsions can improve sprayproperties by explosive vaporization of the low boiling constituentsin the micelles. Pyrolysis, or thermal cracking, is the process of con-version of one substance into another one (cleavaging chemicalbonds to yield small molecules), by means of heat or with the aid ofa catalyst, in the absence of air or oxygen. The equipment for pyroly-sis is expensive and additional distillation equipment for separationof the various fractions is needed (Jain and Sharma, 2010; Parawira,2010).

Transesterification is the most popular method of convertingJ. curcas oil into biodiesel. Transesterification is the process of

exchanging the organic group (R1) of an ester with the organicgroup (R2) of an alcohol (1).

R1 OOCR + R2 OH ↔ R2 OOCR + R1 OH (1)

N. Contran et al. / Industrial Crops and Products 42 (2013) 202– 215 211

Table 5Pests (with relative infested plant species) and host of human diseases potentially controlled by J. curcas bio-pesticide preparations (Heller, 1996; Gübitz et al., 1999).

Pest Infested species Preparations

Helicowerpa armigera Gossypium spp. Crude oil, seed aqueous acetone extractsAphis gossypii Gossypium spp. Crude oil and oil aqueous extractsPectinophora gossypiella Gossypium spp. Oil aqueous extractsEmpoasca biguttula Gossypium spp. Crude oilCallosubruchus chinensis Zea mays Emulsifiable concentrate oilSitophilus zeamays Zea mays Emulsifiable concentrate oilSesamia calamistis Sorguhm spp. Crude oil and phorbol estersBusseola fusca Sorguhm spp. Crude oilPhthrimaea opercullela Solanum tuberosum Crude oilCallosobruchus maculatus Fabaceae spp. Crude oilCallosobruchus chinensis Fabaceae spp. Crude oil

Host Human disease Preparations

Lymnaea auricularia rubiginosa Liver flukes (Trematoda class) Seed and oil extractsLymnaeidae family Fasciola gigantea Seed and oil extractsPomacea spp. Angiostrongylus cantonensis Seed and oil extractsBiomphalaria glabrata Schistosoma sp. Seed and oil extractsa

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In presence of alcohol, the transesterification of J. curcas triglyc-rides involves three consecutive reversible reactions: triglyceridess converted stepwise to diglyceride, monoglyceride, and lastly tolycerol, giving one ester in each step (2). The alcohols used inhe transesterification process are methanol, ethanol, propanol,utanol and amyl alcohol. Methanol is the most common used alco-ol because of its low cost and its physical and chemical advantagess polar and short chain alcohol (Parawira, 2010). When the highiscous component glycerol, an important by-product with numer-us applications (FACT, 2010), is removed, the methyl esters of J.urcas fatty acids form biodiesel (Jain and Sharma, 2010).

H2-OOC-R1 CH2-OH R’-OOC-R1| |H-OOC-R2 + 3R’-OH ↔ CH2-OH + R’-OOC-R2

| |H2-OOC-R3 CH2-OH R’-OOC-R3

riglycerid + Alchol ↔ Glycerol + Esters (2)

A catalyst is usually used to improve and enhance the reac-ion rate. Several catalysts and transesterification methods haveeen investigated: (i) alkali catalyzed transesterification, (ii) acidatalyzed transesterification, (iii) enzyme-catalyzed transesterifi-ation, (iv) non-catalytic supercritical alcohol transesterification,nd (v) ultrasound assisted transesterification (Koh and Ghazi,011). Transesterification characteristics and reaction variables areeported in Table 6. Reaction temperature, molar ratio of alcohol toil, concentration of catalyst, and reaction time influence trans-sterification processes in all the five methods. Further studiesn these variables should be carried out in order to improve theiodiesel yield.

In the alkali catalyzed transesterification, the catalyst is a baseuch as sodium hydroxide, potassium hydroxide, or carbonates.his transesterification is usually preferred over other transes-erification methods because of the higher reactivity and the

ilder process conditions such as the lower temperature requiredGeorgogianni et al., 2009). The disadvantage of this process is thatransesterification will not occur if the FFA content in the oil isbove 1% and, prior to the transesterification, pretreatment pro-esses have to be performed. The presence of FFA (15%) and watern J. curcas oil induces negative effects during the transesterifica-

ion reactions since they cause soap formation, consume catalysts,nd reduce its effectiveness, resulting in a lower conversion (Jainnd Sharma, 2010). Actually, FFA (R1 COOH) react with the alkaliatalyst (e.g. sodium hydroxide NaOH) to form soap (R1COONa)

Emulsifiable concentrate oil

ich contain saponins) result toxic.

and water, reducing the catalyst effectiveness and ester conver-sion, while water hydrolyzes triglycerides to diglycerides, formingmore FFA. Many pretreatment methods have been proposed andestablished. However, the esterification of FFA with alcohol (usu-ally methanol) in the presence of acidic catalysts (usually sulfuricacid) is the most commonly applied method, for the simplicity ofthe process and the capacity of the acid catalysts to convert FFAinto the correspondent esters (3) (Leung et al., 2010).

R1 OOCH + R2 OH ↔ R1 COOR2 + H2O (3)

A transesterification reaction starts when the oil, alcohol andcatalyst are mixed and stirred in a reaction vessel either in a labscale small flask or larger scale. In both cases a high yield of biodieselcan be obtained as long as oil, alcohol and catalyst are in the opti-mum ratio (Koh and Ghazi, 2011). The glycerol phase is muchdenser than the biodiesel phase and settles at the bottom of thereaction vessel, allowing the separation of the two phases. Thisseparation can be observed within 10 min and can be completedwithin several hours of settling. The operating parameters whichaffect transesterification reactions have been studied in detailed,allowing to reach methyl ester yield above the 90% (Koh and Ghazi,2011). For an effective transesterification of J. curcas oil possibleoptimum variables are 20% methanol (by weight of oil), 5:1 molarratio of methanol to oil, and 1.0% of NaOH as a catalyst (by weightof oil). A maximum methyl ester yield of 98% was obtained after90 min with a 60 ◦C reaction temperature (Chitra et al., 2005).

In the acid catalyzed transesterification, the catalyst is an acidsuch as sulfuric acid, sulfonic acid, phosphoric acid, or hydrochloricacid (Georgogianni et al., 2009). The acid catalyzed transesterifica-tion process is not very popular due to the slow reaction rate andthe high methanol to oil molar ratio requirement. In addition, anacid catalyst has a lower activity and the transesterification reactionoccurs at a higher process temperature than for the alkali catalyzedreaction (Georgogianni et al., 2009). On the contrary, the advantageof using this method is the tolerance towards the presence of highFFAs in the oil. In fact, acid catalysts can directly produce biodieselwhen FFA oil content is greater than 6%. Acid catalysts with sulfuricacid can simultaneously conduct esterification and transesterifica-tion by giving a high yield in esters (Koh and Ghazi, 2011).

Recently, enzymatic transesterification using a lipase cata-

lyst has attracted much attention for biodiesel production dueto the easy product separation, minimal wastewater treatmentneeded, easy glycerol recovery, absence of side reaction, and,overall, the biocompatibility, biodegradability and environmental

212 N. Contran et al. / Industrial Crops and Products 42 (2013) 202– 215

Table 6Characteristics and reaction variables of several transesterification methods of J. curcas oil.

Alkali catalyzed Acid catalyzed Enzyme catalyzed Supercritical

Alcohol Methanol Methanol Methano-ethanol MethanoMolar ratio (alcohol to oil)a 5:1–12:1 6:1b 1:1–4:1 3:1–43:1Catalyst NaOH, KOH H2SO4 Lipasec –Catalyst amount (wt% of oil)a 0.55–6 15 4–10 –Reaction conditiona 60–70 ◦C 24–120 min 60 ◦C 24 h 30–50 ◦C 8–60 h 290–320 ◦C 4–15 min 8–11 MPaAlkyl ester yield (%)a 90–99 99.8 80–98 99–100

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cceptability of this biotechnological procedure (Raman et al.,008). However, both the complexity of the lipase purification pro-esses and the cost of the enzymes remain a barrier for its industrialmplementation, and the reaction yields are still unfavorable com-ared to the alkali catalyzed reactions (Parawira, 2010).

The non-catalytic supercritical alcohol transesterification andhe ultrasound assisted transesterification are implemented inrder to reduced the processing time and phase separation time.nder the supercritical condition, the transesterification processan be completed in a few minutes with a relatively high yield,nd the biodiesel purification can be achieved efficiently as noatalyst is required preventing soap formation. However, the draw-acks of this supercritical transesterification process are due tohe high temperature and pressure, resulting in the high cost ofhe apparatus (Koh and Ghazi, 2011). During transesterification,ltrasonication provides both the mechanical energy for mixingnd the activation energy required to start the transesterificationeactions. This allows the increase of chemical reaction speed, anfficient methanol to oil molar ratio, and a high biodiesel yield, withess energy consumption compared to the conventional mechanicaltirring methods (Koh and Ghazi, 2011).

After separation from the glycerol phase, crude biodiesel isainly contaminated with residual catalyst, water, un-reacted

lcohol, free glycerol, and soaps generated during the transester-fication reaction (Schumacher, 2007). Normally, crude biodieselndergoes through a neutralization step, an alcohol stripper, andnally through a washing step (Fig. 2). In the neutralization step,cid is added to crude biodiesel to neutralize any remaining catalystnd to split any soap. Soap reacts with the acid to form water sol-ble salts and free fatty acids. Then, un-reacted alcohol is removedith distillation equipment to prevent excess alcohol from enter-

ng the wastewater effluent. Finally, biodiesel is purified throughater washing, dry washing, or membrane extraction methods, in

rder to wash out the remnants of the catalyst, soaps, salts, resid-al alcohol, and free glycerol from the crude biodiesel (Leung et al.,010).

J. curcas biodiesel has comparable properties with those of fos-il fuel and conforms to the latest standards for biodiesel, such asuropean (EN 14214:2003) and USA (ASTM D 6751) (Table 4). Stan-ardization according to Country defined standards for biodiesel is

prerequisite for successful market introduction and penetrationf J. curcas biodiesel (Parawira, 2010).

Biodiesel storage is quite important to preserve the quality stan-ards. There are several key factors which have to be consideredor the biodiesel storage, including exposure temperature, oxida-ive stability, fuel solvency, and material compatibility (Leung et al.,006). Biodiesel should be storage in aluminum, steel, teflon, anduorinated polyethylene or polypropylene tanks. The biodieseltorage temperature ranges generally between 7 ◦C and 10 ◦C, in

rder to avoid the formation of crystals which can plug fuel linesnd fuel filters. If the storage of biodiesel or biodiesel blends lastsore than 6 months, an antioxidant additive should be used. More-

ver, since water contamination will lead to biological growth in

010; Koh and Ghazi, 2011).

the fuel, a biocides should be added in the stored fuel (Leung et al.,2010).

The by-product glycerol is also very important due to itsnumerous applications in different industrial products such asmoisturizers, soaps, cosmetics, and medicines (Achten et al., 2008).It is extremely effective for washing shearing shed floor, so it canbe used as a heavy duty detergent and degreaser. Typically glyc-erol obtained after the transesterification process is constitutedof maximum 50% glycerol and mainly contains water, salts, un-reacted alcohol, and unused catalyst. Generally, water and alcoholare removed to produce 80–88% pure glycerol which can be sold ascrude glycerol. In more sophisticated operations, the glycerol is dis-tilled to 99% or higher purity and sold in different markets. (Leunget al., 2010).

3.6.3. Products and uses of seed cakeAfter oil extraction from seeds, the remaining J. curcas seed or

press cake, characterized by high protein and nutrients content andhigh calorific value, has a wide variety of applications as organicfertilizer or fuel, for biogas production, or, after conversion, as highprotein animal feed (Ye et al., 2009). Considering the large quan-tity of seed cake generated after oil extraction and all the possibleapplications, its commercial use is vital for economic viability ofthe J. curcas system. The storage requires several precautions. Theoptimal condition to store J. curcas cake is below 6 ◦C, avoiding highhumid temperature, since seed cake is subjected to fungal attack.An alternative storage method is to dehydrate the seed or presscake, obtaining a low moisture content cake, which can be storedin hermetic containers or in dry and cool places (FACT, 2010).

3.6.3.1. Fertilizer. Nutrient-rich seed cake is suitable as fertilizer.Application of J. curcas seed cake as fertilizer (0.75–3 t ha−1) signif-icantly increases the seed yield of J. curcas plantation of 13–120%(Ghosh et al., 2007) and the seed yield of edible crops such asPennisetum glaucum (5 t ha−1), Brassica oleracea (2.5 t ha−1), Oryzasativa (10 t ha−1) respectively of 46%, 40–113%, and 11% (Achtenet al., 2008). Additionally, since the phorbol esters founded in theseed cake are completely biodegradable in soil and their degradedproducts appear to be innocuous, the seed cake application as fer-tilizers has no impact on the beneficial microbial communities,insects, invertebrates and plant/animal communities (Devappaet al., 2010). Further studies should reveal the absence/presenceof phorbol esters in human consumption crops grown on J. curcasseed cake fertilized lands.

3.6.3.2. Combustible fuel. Seed or press cake, having high calorificvalues, can be burned as fuel (Achten et al., 2008). In order toimprove its performance as fuel, seed or press cake can be pressedinto cake-briquettes, which are characterized by a higher density

than simply cake and consequently higher energy content per kg(FACT, 2010). Briquetting machineries are already available. Forexample, low pressure briquetting machines operate by increas-ing the cohesion force between press cake particles and by adding

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f binding materials. The disadvantage of cake-briquettes is theuge quantity of smoke emitted during the combustion (FACT,010). Additionally, press cakes or briquettes could be turned

nto charcoal-dust or charcoal-briquettes respectively, increasingheir energy content by reducing the weight. In a similar process,harcoal-dust can be transformed into charcoal-briquettes. Usinghe traditional way of making charcoal (covering with soil), a bri-uette can completely be turned into charcoal. Charcoal-briquettesurn more easily and produce less smoke emission than burnt cake-riquettes (FACT, 2010).

.6.3.3. Biogas production. Seed cake and parts of J. curcas fruitsan be used as feedstock for biogas production through anaerobicigestion. Between 0.4 m3 kg−1 and 0.6 m3 kg−1 of biogas could bebtained from the J. curcas seed cake, depending on the inoculume.g. pig manure, microbial consortia) and on the type of cake (e.g.ry seed cake, solvent extracted kernel, or mechanically de-oiledake) (Achten et al., 2008). Biogas, a mix of methane and carbonioxide (60:40) with a caloric value of about 20 MJ kg−1, is mainlysed for cooking and lighting, but it can also be used for runningas engines in large scale production. However, the fermentationrocesses need a huge amount of water.

The slurry, the by-product of seed cake fermentation, can besed as fertilizer. It has a high nutrient volume and, in addition,ll pathogens are killed during fermentation. Unfortunately stud-es on use of biogas slurry as fertilizer are still in the early stagesGunaseelan, 2009). Recently, experimentation on solid-state fer-

entation of J. curcas seed cake showed that it could be a goodource for a low cost production of industrial enzymes (Mahantat al., 2008).

.6.3.4. Protein animal feed. Additional feed amounts obtained asy-product of oil production is a goal which should be reached, inrder to contribute to the achievement of a high nutritional valueiet also in developing countries. A high quality protein concen-rate, with the level of essential amino acids (except lysine) higherhan the FAO reference protein, could also be produced from the J.urcas nitrogen-rich seed cake (Makkar et al., 2008).

Anyway, with the only exception of the Mexican edible/non-oxic genotypes, phorbol esters have to be removed and trypsinnhibitor and lectin inactivated by heat treatment, in order to allowhe use of the protein concentrate seed cake as an edible ingredi-nt in livestock feed (Makkar et al., 2008). Seed cake detoxifications a difficult and complicated process, due to the high number ofnti-nutritional and toxic factors (Devappa et al., 2010): the bestxtraction procedures available for phorbol esters removal elimi-ate about half of the toxic compounds. Till now, the detoxificationas only been successful at laboratory scale and it is not suitableither for small-large scale or for local use (Makkar et al., 2008).ven the non-toxic varieties may need treatments to avoid clinicalroblems, due to the presence of anti-nutritional components. Inrder to increase the benefits of J. curcas, researches on seed cakeetoxification methods are needed.

.6.4. Fruit husk and shell usesFruit husks and seed shells, the by-products of dehusking and

ehulling processes, are other important by-products of J. curcasil production (Fig. 1). These by-products, having high nutrientontent and calorific values (Table 1), can be used directly as com-ustible fuel, as green manure, or for biogas production (Achtent al., 2008). The direct combustion is possible due to the highalorific values of husk, similar to fuelwood, and to the high shell

ulk density. Additionally, in order to improve its performance asuel, the husk can be dried and ground to a powder and aggre-ate into husk-briquettes (IFAD-FAO, 2010). Husks, shells and thesh left after husk-briquettes combustion, being high in potassium,

d Products 42 (2013) 202– 215 213

may be applied to J. curcas trees as mulch, promoting nutrientre-cycle (IFAD-FAO, 2010). Finally, biogas can be produced fromhusks (Gunaseelan, 2009).

4. Conclusion

J. curcas may offer a sustainable alternative as energy crop and itsproductive chain offers smallholders an opportunity to create addi-tional incomes. By 2008, J. curcas had already been planted over anestimated 900,000 ha globally, of which an overwhelming 85% wasin Asia, 13% in Africa and the rest in Latin America, and, by 2015, it isexpected to be planted on 12.8 million hectares worldwide (GEXSI,2008). However, there is still much uncertainty around this smalltree and too many issues are without accurate responses. In thispaper, each phase of J. curcas productive chain has been traced andsummarized, in order to logically organize the knowledge aroundJ. curcas system and to assess its weaknesses.

Yield expectations are not predictable yet. Besides some knowl-edge gaps in the basic agricultural practices, the main issue isprobably the shortcoming in the long process of selection, breeding,and domestication of the most productive varieties of J. curcas. Aworldwide collection of J. curcas germplasm should be carried out,followed by a systematic inventory of provenance and by trials andgenetic tests over a range of different environments. Geneticallydivergent material among and within natural populations shouldbe investigated. Genetically superior planting material, in termsof both seed yield, seed size, oil yield, oil quality and adaptabil-ity to local environmental conditions, should be selected. Finally,based on these investigations and selections, programs of systemicand selective breeding and domestication should be carried outwith the aim at producing high yielding plants. The uncertaintyon the best method of propagation for specific (environmental andsocio-economic) context is another critical point in the J. curcaschain. The irrigation phase should be carefully investigated, evenif J. curcas is a drought avoidant plant, able to survive over a widerange of xerophytic habitats, due to its ability to enhance the waterefficiency shifting from C3- to CAM-metabolism under low wateravailability circumstances. However, the optimal condition whichallows acceptable growth and yield is under annual precipitationabove 600–900 mm (Maes et al., 2009). The previous not scientif-ically supported idea that J. curcas could grow and be productiveeven with limited water availability, has led to the failure of variousprojects implemented in arid areas. Instead, the large scale projectsfocused on biodiesel production, providing a strong irrigation inorder to obtain high yields, often use water to the detriment of foodcrop cultivations, reducing the potential sustainable advantages ofthis tree. The regular post planting agronomic practices seem tobe well established at least in countries such as India and China(Gour, 2006). Unfortunately, it is still unknown if these agronomicpractices can be successfully applied in other contexts, such as inarid and semi-arid areas of Africa. Furthermore, J. curcas industryis still in its infancy and a commodity market for J. curcas oil andby-products does not exist yet.

On the contrary, productive processes of J. curcas products,especially those linked to the biodiesel production at large scale,are improving rapidly (Achten et al., 2008; Koh and Ghazi, 2011).As far as J. curcas environmental problem mitigation is concerned,soil structure improvement, soil erosion prevention, and marginalland or abandoned farmland reclamation promotion are plausibleachievable benefits, which should be in any case confirmed andbetter explored. The greenhouse gas saving of the biodiesel J. cur-cas chain is another key positive feedback. Since few studies on this

topic have been conducted so far, we preferred to not deal with thisparticular topic in this review. Anyway provided data are encour-aging and estimated greenhouse gas saving is around 39–48% (Pazand Vissers, 2011).

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In the assessment of J. curcas system potentialities and critical-ties, a key point is represented by its sustainability at global level.arge-scale production schemes may heavily distort local economy,ocial systems, and environment. Furthermore, in order to preservehe distinctive sustainable traits of J. curcas chain, particular atten-ion should be dedicated to trade-offs among its several issues andses: trade-offs between marginal land reclamation and profitableil production, trade-offs between local and large-scale economicnterests, or land use policy trade-offs between poor quality and fer-ile soil utilization. Small scale models of community based projectsre seen to positively contribute to rural livelihoods in developingountries (Dyer et al., 2012). Embedding the production of J. curcasiodiesel within energy policies, strictly controlled in terms of envi-onmental impact and sustainability, could be a starting strategy toeduce the dependency on fossil fuels and a possible option for cli-ate change mitigation. Anyway, until further researches will not

e globally conducted and results deeply analyzed, the prudencerinciple should be applied.

cknowledgments

The research was funded by Regione Autonoma della Sardegnaith a research grant co-financed with the PO Sardegna FSE

007–2013 L.R. 7/2007 “Promozione della ricerca scientifica eell’innovazione tecnologica in Sardegna”. The paper has been

nspired also by the on-field experience gained by the authorsn the context of the project “Use of Jatropha plant to improveustainable renewable energy development and create income-enerating activities: an integrated approach to ensure sustainableivelihood conditions and mitigate land degradation effects in ruralreas of Ghana (Ghaja)”, within the “Environment and sustainableanagement of natural resources, including energy” programme

EuropeAid), which is here acknowledged.The authors wish to thank Francesco Fava for his helpful com-

ents and suggestions, and their partners of the Ghaja project:eorge Yaw Obeng, Micheal Adjaloo, Stephen Kwasi Nutsugah,

ames Mantent Kombiok, Joseph Yeng Faalong, Christopher Akai,homas Sayibu Imoro Sr., Osmaan Sahanoon, and Sualisu Fuseini.

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