Chapter-I ~~~~~~~~~~~~~~~~~~~~~~~
Introduction ~~~~~~~~~~~~~~~~~~~~~~~
1
The world is coming to recognize the grim truth that ultimately the population growth
will outstrip food suppliers with apocalyptic results. About 36 million people die
every year due to hunger or as a result of hunger (Gasperini and Maguire, 2001). A
total of 842 million people or around one in eight people in the world, were estimated
to be suffering from chronic hunger, regularly not getting enough food to conduct an
active life (FAO, 2013). There are 16 million people undernourished in developed
countries (FAO, 2012). If the current average birth rate continues, the world’s
population will grow from the current 6.7 to 9.2 billion by the year 2050, most of
which will be in the less developed countries, the countries least able to feed their
children (WHO/UN, 2007). Feeding 9.2 billion people at the current dietary levels
presents the staggering necessity of increasing the earth’s food producing capacity to
a rate never seen before (Ghaly and Alkoaik, 2010). More than half the world’s
population sees its health, even its survival, threatened by serious nutritional
deficiencies. Protein deficiency is at the root of problems of growth and immunity.
Vitamin A deficiency affects more than 10 million children, causing half the blindness
in the world. Hypovitaminosis-A is defined by World Health Organization (WHO) as
the second priority after protein malnutrition. Iron deficiency, even more widespread,
since according to United Nations International Children’s Emergency Funds
(UNICEF), 500 million children suffer chronic anemia with its accompanying
immunity problems and hindrance to physical and mental growth. For decades, WHO
has had a programme for fighting these three deficiencies but while the need is great
the cost is high (Zanin, 2009).
People whose diet provides their body with a regular and adequate supply of
the nutrients essential for growth and health are said to be well-nourished. Those
whose diets fall short on one or more of these essential nutrients are malnourished.
Malnutrition is the biggest health problem in the world. Protein deficiency or protein
caloric malnutrition (PCM) is one of the major nutritional problems in the developing
world (Latharn, 1997). Approximately, 60% of the 10.9 million deaths each year
among children under the age of five in the developing world are attributed to
malnutrition (WHO, 2002a). It is estimated that 730,000,000 children in the world are
currently malnourished (FAO, 2012). India is one of the highest ranking countries in
the world for the number of children suffering from malnutrition. The prevalence of
underweight children in India is among the highest in the world, and is nearly double
that of Sub-Saharan Africa with dire consequences for mobility, mortality,
2
productivity and economic growth (The World Bank, 2009). The Global Hunger
Index (GHI) report ranked India 15th, amongst leading countries
with hunger situation (GHI, 2011). In India, around 46 per cent of all children below
the age of three are too small for their age, 47 per cent are underweight and at least 16
per cent are wasted. Many of these children are severely malnourished. One in every
three malnourished children in the world lives in India (The World Bank, 2009).
Malnourished children are smaller and weaker than their peers. They have more
frequent and more severe intestinal and respiratory infections, and they take longer to
recover from them. Their attention span is shorter and their ability to concentrate or
remember things is less than that of well nourished children. Their life expectancy is
shorter. In severe cases, they suffer permanent mental and physical damage in their
first tender years of life from a lack of enough food (Cameron and Hofvander, 1983).
In a world where the struggle to succeed can be very tough, they begin life at a
tremendous disadvantage, through no fault of their own. The suffering and loss of
human potential from malnutrition is unnecessary. Malnutrition is preventable in very
much the same way as smallpox and polio are. While there is no vaccine against
malnutrition, the same creative forces that developed the vaccines and the same
determination that makes sure children are vaccinated against crippling diseases can
free our children from the plague of malnutrition. FAO has, for long, tried to define
criteria for quantifying malnutrition. In the 1970’s it put the accent on protein deficit.
Later, it defined malnutrition (or chronic underfeeding) by the single deficit of energy
when the level is below an annual average intake of 2, 200 cal/day, 780 million
individuals are concerned, of whom 195 million are children under 5 (FAO/WHO,
1992). However, this method does have the disadvantage of failing to take into
account deficiencies in protein, vitamins and minerals. The main ones being iron,
vitamin-A, iodine and calcium. Now, some populations with low income, while
satisfying the criterion of 2, 200 cal/day, suffer shortages of nutrients. This refers to a
much greater number than that estimated by FAO: more than 2000 million individuals
are affected by these two forms of malnutrition: caloric and specifically deficient in
one or more nutrients (Adeyeye & Omolayo, 2011). Specific nutritional deficiencies
can cause serious health problems, especially in children: low weight, slow growth,
mental retardation, weakened immunity, sometimes death. In fact, it is during the first
5 years that the consequences are most dramatic: the body and especially the nervous
3
system are in a period of rapid growth and need the presence for their development of
proper nutrients (King and King, 1991).
A large section of the populations of the underdeveloped world lives under
substandard conditions, including nutritionally inadequate diets. The available food
supplies are not sufficient to meet the demands of the growing population. Further,
shortage of supply of good quality protein food is also a serious concern of the feed
producers to produce animal protein. Use of human dietary and animal protein such as
soybean and fish in livestock and fish diets, particularly in fish meals is unaffordable
in the developing economies. This limits aquaculture development since fish requires
more protein than terrestrial animals (Wilson, 1991). These considerations have
necessitated the search for additional sources of protein. The widening gap between
the supply and demand can be bridged by increasing the production of food and by
supplementing the existing resources with novel foodstuffs. The development of
novel protein sources such as Fish Protein Concentrate (FPC) (Pariser et al., 1978;
Sikka et al., 1979), Single Cell Protein (SCP) (Tannenhaum and Wang, 1975;
Ferrianti and Fiechter, 1983), Soybean Protein (SBP) (Mendez et al., 2002; Bhatia and
Greer, 2008) and insect protein (Ghaly and Alkoaik, 2010) have made significant
contributions toward the alleviation of the world protein deficiency (Kuijer and
Wielenga, 1999). However, there is still an estimated one billion people suffering
from protein deficiency and malnutrition (FAO, 2008; WHO, 2002b). Therefore, new
methods of feeding the underfed world population, especially in the less developed
countries, have to be developed. Those methods that will guarantee a continuous
protein supply require most serious attention since most malnutrition cases have been
found to be a result of protein insufficiency. There is agreement among scientists that
protein malnutrition contributes to the high death rate among infants and children of
the less developed countries and causes among the survivors debilitating weakness,
higher susceptibility to disease and irreversible brain damage (FAO, 2008; WHO,
2002b).
In most under developed countries, the majority of the people are vegetarian
and even where it is possible to obtain meat the price is too high that most families do
not have meat more than once a week (Ghaly and Alkoaik, 2010). Therefore,
expansion of present agricultural practices into marginal lands is expected to solve
this chronic world food shortage. The process of photosynthesis is the only non
depletable protein source and can supply some essential amino acids as well as
4
provide adequate nitrogen in the diet for synthesis of non essential amino acids
(Kinsella, 1970; Staman, 1970). However, only a very small percentage of the world
edible plants are being utilized for human food. Furthermore, about 90% of the world
plant food comes from only 20 crops and in many countries only 6 crops are actually
exported/imported (Parrish et al, 1974). Leafy vegetable protein is about half the
vegetable protein content in the human diet and probably contributes more to the
world protein total than do fish, although less attention is given to it.
Two factors limit the nutritional value of plant leaves to monogastric animals:
The high fibre content and the indigestibility of cellulose (Kinsella, 1970). Normally
animals assimilate the plant protein and they are in turn are consumed by human and
through this food chain man avoid the cellulose. However, this food chain system is
very inefficient in under developed countries since most people do not eat enough
animal protein for economic reasons. Moreover, only 8-20% of the plant protein
consumed by animals is recoverable as protein for human nutrition. Thus, more
efficient ways of utilizing plant protein must be found.
Although protein is costly to produce, it is the greatest limitation to growth
and good health (Altschul, 1965). There is a great disparity in protein usage by the
various nations. Figure 1.1 shows the global geographical distribution of malnutrition
(Ghaly and Alkoaik, 2010). The low protein content in the diet is associated with the
low level of animal protein supply and results in acute clinical symptoms, particularly
among children. Moreover, even when children survive the aftermath leaves its mark
on adulthood and renders the adults more susceptible to further debilitations when
exposed to diseases which normally would be tolerated by people with a history of
good nourishment (Sodamode et al., 2013). Therefore, protein deficiency requires
special attention for the following reasons: (a) the scientific evidence available now
points to the fact that apart from calorie shortage, protein deficiency diseases are the
major cause of malnutrition in low income countries, (b) protein deficiencies present
special difficulties because of inadequate methods of diagnosis, (c) protein
deficiencies in under developed countries are always linked with other deficiencies so
that accurate clinical diagnosis and epidemiological studies may be difficult, (d)
proteins are complex chemical compounds and there are wide variations in their
composition based on their sources, storage, processing and cooking, (e) proteins are
required in considerable amounts each day and deficiency cannot (except possibly as
an emergency measure) be dealt with through provision of medicine and (f) proteins
5
are normally among the most expensive foods and their immediate provision in many
countries may entail imports which could be difficult based on general financial
grounds in poor countries (Kinsella, 1970).
It is not enough to present statistics which indicate that protein supplies are
inadequate for large population groups. It is, thus, necessary to demonstrate that
malnutrition actually occurs as a clinically identifiable disease. The most disastrous
consequences occur in children where protein malnutrition manifests itself in forms of
two notorious diseases: kwashiorkor and Marasmus (Abowei & Ekubo, 2011).
Kwashiorkor is a case of severe protein deficiency with the absence of serious
calorie deficiency (Amadou et al., 2010; Loubna & Nacer, 2011). It is a medical name
for malnutrition when a child is weaned and the diet that replaces breast milk is high
in carbohydrates and deficient in protein as is common in many parts of the world
where the bulk of the diet is made of starchy vegetables (Williams, 1953). The name
is derived from one of the languages in coastal Ghana, translated “first-second”. It
means the rejected one, reflecting the development of the condition in the older child
after the second one is born. A picture of a child suffering from Kwashiorkor disease
is shown in Figure 1.2 (Ghaly and Alkoaik, 2010). Early symptoms of kwashiorkor
disease include: Fatigue, irritability and lethargy. As protein deprivation continues,
growth failure, loss of muscle mass, swelling edema and decreased immunity occur.
Other conditions include: Edema of the legs and feet, a pot-belly, light colored-thin
hair, skin depigmentation, shiny skin, dermatitis, loss of teeth and enlarged liver
(Cilinberto et al., 2005). Protein function in the body is to keep the blood from leaking
out of the blood stream into the body tissues and cavities. When blood proteins are
very low, serum seeps into the soft tissues and abdominal cavities causing defuse
body swelling or edema and abdominal bloating or ascites. Aside from the direct
effect of the disease, there are some secondary effects including: Lowered resistance
to infection and the infection in turn reduces the capacity of the child to be nourished
and enhances the malnourished condition. Kwashiorkor typically occurs at about age
one after infants are weaned from breast milk to a protein deficient diet of starchy
gruels or sugar water, but it can develop at any time during the formative years
(WHO, 2002b; Krawinkel, 2003). Kwashiorkor patient’s mortality in poor countries is
18-30% (WHO, 2002b). Mortality rate of children 1-4 years of age in countries where
Kwashiorkor is rare is only 1.0-3.8 per 1000 population where mortality in countries
Figure 1.1:
2010).
(a)
Figure 1.2
edema and
2010).
: Global geo
2: Picture o
d (b) Signif
ographical d
of children
ficant weigh
6
distribution
with kwas
ht loss, fat
n of malnutr
(b)
shiorkor (a)
igue and p
ition (Ghaly
) Significan
pot-belly (G
y and Alkoa
nt hair thin
Ghaly and A
aik,
ning and
Alkoaik,
7
Figure 1.3: Picture of a child with marasmus (Ghaly and Alkoaik, 2010).
8
where kwashiorkor is prevalent ranges from 12-60 per 1000 for the same age group
(Badaloo et al., 2006; Pirie, 1975a).
Marasmus is a severe general malnutrition syndrome of both calorie and
protein (Amadou et al., 2010; Loubna & Nacer, 2011). It affects infants age 6-18
months old as a result of breast feeding failure or a debilitating condition such as
diarrhea. Figure 1.3 shows a picture of a child with marasmus (Ghaly and Alkoaik,
2010). The child looks emaciated and the body may be reduced to less than 80% of
normal weight for that height. The malnutrition leads to extensive tissue and muscle
wasting as well as variable edema, dry skin, loose skin folds hanging over the glutei
and axcille, vomiting, lethargy and impaired immunity. The afflicted child becomes
fretful, irritable and voraciously hungry (Cilinberto et al., 2005). Protein malnutrition
in adults is not easy to detect as in children and yet there may be far reaching effects
including the prospect of permanent damage to organs in those adults who had a
protein malnutrition experience when young which would influence the later habits
and activities (WHO, 2002b).
The increasing storage of food protein for human and animal consumption has
drawn attention to fresh green leaves as source of protein. Pirie, 1966 has suggested
that “when vegetable consumption is accepted, protein extracted from leaves should
be used as a supplementary protein concentrate especially in wet tropical countries”.
Shortage of supply of the good quality protein for meeting the requirements of
increasing animal and human population has necessitated search for addition sources
(Bedor & Kulkarni, 2011). The unconventional source of protein which include
oilseed meals, fish protein concentrate, single cell protein and perhaps algal and leaf
proteins have tremendous scope for developing low cost protein foods (Ghaly et al.,
2012; Olaofe et al., 1994) and thus filling the huge “protein-gap” that exists between
the overall requirements of protein foods for adequate nutrition of the population and
the total availability of such protein foods.
Out of all the unconventional source of protein, leaf protein appears to have
better exploitation in the light of excessive of photosynthesis and availability of
abundant green vegetation (Srivastava & Mohan, 1981). Leaf concentrate can be a
powerful tool in the effort to defeat malnutrition. Pirie, 1966 suggested incorporation
of leaf protein concentrate (LPC) into human food. Shah, 1976 extracted proteins
from grasses which contained 35%-60% protein, 6%-10% crude lipids and 1.01-1.47
mg/g of carotene. Research interest has been focused on different leaf meals as
9
protein sources in animal feeds (Abowei & Ekubo, 2011). Constraints to enhanced
utilization of seeds and leaves of fodder trees includes high fibre content, presence of
anti-nutritional factors (ANF) and deficiencies of some essential amino acids.
Processing of leaf into leaf protein concentrate reduces fibre content and some ANFs
(Pirie, 1971). Concentrates are feedstuffs high in digestible nutrients and low in fibre.
Better use of plants to deal with problems of poverty, food and nutritional security,
income generation and environmental health would revive such plants that are
currently neglected as increase demand would encourage farmers to increase their
production.
Leaf proteins have been found to have great nutritive value than most of the
pulses, resembling skim milk in the diet of infants recovering from kwashiorkor. It
also helps avert certain diseases associated with malnutrition, in particular anemia,
diarrhea, respiratory infections and nutritional blindness. In very young children they
allow normal development of the brain and thus safeguard the ability to benefit from
education and to improve the chance of a better life (Zanin, 2009). It has been
advocated as a potential protein food source for human consumption (Pirie, 1971).
Trees have also been suggested as a possible source of leaf protein food in
addition to already identified weeds, cultivated crops and wild plant species. The
production of protein food from tree leaves appears to have a unique advantage as
they do not involve recurring cost of cultivation as in the case of crops (Sodamode et
al., 2013; Pirie, 1968b). It has been estimated that trees may yield 6-7 tones of protein
annually per ha (Siren et al, 1970). However, the trees have not yet been sufficiently
studied for their leaf protein production potentiality. Pirie, 1968b also advocate the
potentiality of tree leaves for leaf protein production.
What is LPC?
Leaf protein concentrate (LPC), a concentrated form of protein derived from
the foliage of plants, has long been recognised (Byers, 1961; Oke, 1973; Pirie, 1971;
Nagy et al, 1978; Saunders et al, 1972) as the inexpensive and most abundant
potential source of proteins for production of animal feed and unconventional foods
because of their capacity to synthesize amino acids from a wide range of virtually
unlimited and readily available primary materials such as sunlight, water, CO2 and
atmospheric N2 (Ravindrian and Blain, 1992; Eggum, 1970). Nutritional value of LPC
extracted from green foliage has been shown to be comparable to that of protein
isolates of animal origin and superior to seed proteins (Morris, 1977).
10
Leaf concentrate is an extremely nutritious food made by mechanically
separating indigestible fibre and soluble anti-nutrients from much of the protein,
vitamins, and minerals in certain fresh green plant leaves. Because it is so rich in beta-
carotene, iron, and high quality protein, leaf concentrate is very effective in combating
malnutrition, especially the anemia and vitamin A deficiency which are prevalent
among children and pregnant women in most developing countries (Kennedy, 1993).
It is easily combined with a variety of inexpensive foods to make culturally acceptable
dishes. Because it takes more direct advantage of solar energy, a leaf crop can
produce more nutrients per hectare than any other agricultural system. Leaf crops can
usually be produced with less environmental impact than grains (Siren et al, 1970).
The simple technology of making leaf concentrate offers a means of capturing a much
greater part of the leaf harvest for direct human consumption. The fibre that is
separated can be used to feed animals and the left over liquid, or "whey" can be used
to fertilize plants, so nothing is lost (Byers, 1961).
LPC has been examined as a human or animal food source, because it is
potentially the cheapest, most abundant source of available protein. Although humans
can derive some protein from the direct consumption of leaves as leaf vegetables, the
human digestive system would not be able to deal with the enormous bulk of leaves
needed to meet dietary protein requirements with leaf vegetables alone (Barbeau,
1989). LPC was first suggested as a human food in the 1960s, but it has not achieved
much success, despite early promise. Pirie, the Noble Prize winner from UK,
reviewed and emphasized importance of its benefits which brought the subject
forward. The increasing reliance on feedlot based animal rearing to satisfy human
appetites for meat has increased demand for cheaper vegetable protein sources. This
has recently led to renewed interest in LPC to reduce the use of human-edible
vegetable protein sources in animal feed (Hussein, 1999).
Apart from lower methionine content, the amino acid profile from most leaf
species compare favorably with those of soya bean, meat, fish and egg and generally,
surpass FAO essential amino acid pattern (Eggum, 1970; Barbeau, 1989). Leaf
protein is a good source of amino acids, with methionine being a limiting factor
(Olaofe et al., 1994). Leaf proteins can also be rich in polyphenols (Rambourg and
Monties, 1983). The challenges that have to be overcome before LPC becomes a
viable protein source for humans include the high fiber content and other anti-
nutritional factors, such as polyphenols, saponins, cyanide, alkaloids and tannins
11
(Ayodeji and Aletor, 2005). Dried LPC contains about 40% crude protein, of which
about three quarters is true protein. The amino acid composition is remarkably
constant regardless of the green fodder used. The biological value of leaf protein lies
between that of soybean and that of milk (Hassan and Umar, 2006). The product is
green and presents no palatability problems when included in mixed feeds.
The basic technology for separating the leaf protein from the fibrous part or
the leaf has been known for about fifty years. The basic steps for the production of
LPC are grinding the plant and separating the juice by pressing. The protein is
dissolved in the juice, after which it is coagulated, usually by heating, and then dried
(Pirie, 1957). Protein that is processed quickly is more readily digested by enzymes,
contains more available lysine, and less methionine sulphoxide than protein processed
more slowly (Saunders et al., 1972).
Green vegetation is the primary replenishable source of food in the world;
numerous technologies have been developed over the last 50 years to separate protein
in leaf from accompanying fibrous material (Adeyeye and Omolayo, 2011). The leaf
extract or juice contains proteins, sugars, salts, lipids and vitamins along with the
moisture in plant. When the juice is heated to over 80oC, or acidified to pH-4.0, green
protein rich curd referred as leaf protein concentrate (LPC) is produced. The LPC can
be separated from deproteinised juice (DPJ) by filtration through cotton cloth. In this
way green foliage can be fractionated mechanically into three fractions: (i) fibrous
pressed crop, (ii) leaf protein concentrate and (iii) deproteinised juice (Wilkins et al,
1977; Pirie, 1978). During green crop fractionation (GCF) the pressed crop residue
(PCR) which is also known fibrous residue, left after the extraction of juice, still
contain from 9 to 16 % crude protein (CP; N x 6.25) in its dry matter (DM) depending
on the species used for fractionation. This can be successfully used as a feed for cattle
(Walker et al., 1983; Joshi, 1983). LPC contain from 40 – 70 % protein (on DM basis)
along with appreciable quantities of β-carotene (pro-vitamin A), vitamin E and
minerals. The LPC can be used as a protein vitamin- minerals supplement in poultry,
calf (Joshi, 1983) or even human nutrition (Pirie, 1978; Shah, 1976). Deproteinised
juice (DPJ) contains soluble components of the plant cell. It is considered as a by-
product of GCF system. This fraction can be used along with PCR in animal nutrition
(Joshi, 1983), for irrigation as a fertilizer source (Ream et al., 1983; Jadhav and
Mungikar, 1998) or for growing useful microorganisms (Pirie, 1971, Pirie, 1978;
Baviskar et al., 1999). It is seldom possible to date precisely.
12
Advantages of LPC
Leaf concentrate is an extremely nutritious food. It is richer in vitamin A and iron
than any commonly available foods. Deficiencies of these two nutrients are two of
the most serious and prevalent health problems in the world today. Leaf
concentrate is also a very good source of high quality protein and calcium, as well
as several other important nutrients (Kennedy, 1993).
It is a very efficient way of using land to produce food, yielding roughly three
times as much protein per hectare as grain crops and five to ten times as much per
hectare as animal rising (Siren et al., 1970).
While the green colour of leaf concentrate foods is unfamiliar, the acceptance of
these foods by children in a dozen different countries has been excellent. As most
parents know, many children all over the world do not like to eat dark green leafy
vegetables (Pirie, 1978).
Leaf concentrate is relatively easy to make. People with little training or education
can make it in rural villages (Ghaly et al., 2012).
It offers a very nutritious food at prices below what foods like meat, cheese, eggs,
or powdered milk cost. It is usually the cheapest dietary source of vitamin A and
iron wherever it is made (Kennedy, 1993).
It is an environmentally sound agricultural technique. Leaf crops protect the soil
from the erosion that has been destroying grain production land. Pesticides are not
needed to protect leaf concentrate crops from cosmetic insect damage since the
leaves are ground to a pulp immediately after harvest (Oke, 1973).
Nothing is wasted in leaf concentrate production. The residual fibre makes an
excellent feed for cows, goats, sheep, horses, rabbits, or guinea pigs. It can also be
used to enrich the soil or in production of bio-gas for cooking. The left over liquid
is rich in nitrogen and potassium, and makes a good fertilizer. It has been used to
produce ethanol as well (Byers, 1961).
Unlike dark green vegetables, leaf concentrate is easy to preserve. It can be dried,
converted to pasta, made into drink mixes or syrups, salted or pickled (Parrish et
al., 1974).
Many of the anti-nutrients found in leafy foods are removed through the leaf
Concentrate process. The hydrocyanic acid, nitrates, goitrgens and free oxalic acid
that limit the usefulness of many leaf crops in the human diet are almost
13
completely removed when the leaves are converted to leaf concentrate (Sogbesan,
2006)).
Leaf concentrate uses far less fuel to prepare than beans, the main high protein
food of the world's poor (Kennedy, 1993).
There have been no known cases of allergic reaction to leaf concentrate since
1975 when the standard processing heat was raised to a minimum of 90 ° C (195 °
F). However, many children are intolerant of other nutrient dense foods like fish
or cheese, and genetic lactose intolerance makes milk a less than ideal food for
children in some regions (CAN, 1993).
LPC as a protein supplement in food/feed
Nutritionists in different part of the world are investigating the possibilities of
supplementing diet with novel source of protein. One such source is leaf protein
concentrate. In order to gain acceptance of novel foods by those who need them most,
special efforts need to be taken towards their popularization. However nutritious or
abundant a novelty is, it may not be adopted unless its palatability has been
determined (Devadas, 1967). Therefore consumer acceptances through persuasion,
education and example are of paramount importance when introducing novel foods.
Amerine et al, 1965 suggested that standardized recipe should be such that it
produces identical result whenever tried under the condition specified. Accordingly,
all the variables such as the ingredients, cooking temperature, duration of cooking, the
quantity of water, salt and condiments used and blending were controlled. For arriving
at the quantity of the LPC to be used, from the nutritional point of view, it was
considered advisable that the LPC furnishes 6-7 g of protein; for this 10-13 g of the
normal product is incorporated (Pirie, 1971).
Use of LPCs as a protein supplement in animal feed has also been
demonstrated (Olvera-Novoa et al., 1990; Abowei and Ekubo, 2012). LPCs for animal
feed currently are manufactured on a large commercial scale from alfalfa (Medicago
sativa) in Europe and the United States (Zanin, 2009). It may also be used in animal
feeds for swine, calves, chickens and fish (Telek and Graham, 1983). Previously,
research on LPCs was aimed mainly at obtaining LPCs for animal feed; lately
encouraging results have shifted interest to its use for humans (Zanin, 2009; Pirie,
1984)
14
Before leaf protein can gain acceptance as a human food, standards of quality
will have to be drawn up. Meticulous care will be needed to meet these standards. The
crop, as harvested, is dirty. It needs careful rinsing to remove dust and other
contaminants from its surface. Otherwise there will be an unacceptable amount of acid
insoluble ash in the final product. The reasons given for extracting the protein with
dilute acid outweigh the disadvantage that these extractions also remove much of the
calcium, magnesium and potassium (Aletor and Adeogun, 1995). These are useful
components of diet, but they are easily supplied in other ways. Coagulation at 800C
kills most of the bacteria and other possibly harmful organism on leaf surface. If this
treatment should not, in some circumstances, be thought adequate, the final product
may be given more intense heat treatments, or hypochlorite or some such agent could
be added to the water in the original rinsing time or to the water used to wash the
protein. The acceptability of crops that have been treated with insecticides or
herbicides is also a matter for experiment. Many are harmless and others are probably
removed from the protein by washing (Pirie, 1971; Pirie, 1978).
Prompted by aforesaid facts, there is a continued interest in developing LPCs
to combat protein deficiency and prospecting for development of LPCs from the trees
acquire significant relevances from scientific and industrial point of view. Since many
tree species are planted as a large scale under agro-forestry/social-forestry programme
and generate huge amount of their leaves as plantation by-products, utilization of
these leaves for production of LPCs could be a practical proposition that could also
generate another income to farmers from these plantations.
15
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