Post on 24-Feb-2016
description
Stevia rebaudiana Bertoni
Chris Stothart
The Sweet Alternative
Outline Overview Historical Perspective Botany Ethnobotany Chemistry Extraction & Commercial Uses Nutrition Regulation Controversies References
Stevia rebaudiana
Overview Common names include: stevia, sweet leaf, sweet
herb of Paraguay, honey leaf, & sugar leaf Increasing popularity of artificial sweeteners over
the past 20 years Demand for “natural” & “healthier” alternatives Perfect social, political, & economic climate Widespread use as a non-nutritive sweetener due
to sweet leaves Much debate over its use & health implications
Stevia rebaudiana
Historical Perspective Used extensively by native cultures of South
America for centuries First introduced to Europe by Spanish
conquistadores in 16th century Reintroduced in early 20th century to
scientific community by Italian-Swiss botanist Dr. Moisés S. Bertoni
1905 – Bertoni classified & described stevia
Stevia rebaudiana
Since 1905 – Stevia has been widely studied Throughout 20th century sweet compounds in
leaves have been isolated, purified, patented, & used in commercial products
1970s – Japan began using stevia in replace of artificial sweeteners & sugar
Largest consumers: Japan, South Korea, Brazil, & South America
Historical Perspective cont.
Stevia rebaudiana
Botany• Tropical perennial &
herbaceous shrub• Native to Central & South
America • Member of Asteraceae
(Sunflower Family)• Grows 65-80 cm tall• Typically found in semi-dry
mountainous environments & grasslands
• Prefers well-drained non-saline soil with pH 6.5-7.5
Stevia rebaudiana
Botany cont.• Simple, opposite green
sessile leaves• Stem, branches, &
leaves are all green & are covered with short, fine whitish hairs
• All green parts taste sweet
• Inflorescences are tiny white & purple disk florets
• Develop achene fruits
Stevia rebaudiana
Stevia rebaudiana
Commercial cultivation
Paraguay, Brazil, Japan, China, Korea, Mexico, USA, Indonesia, Tanzania, & Canada
Ethnobotany Guarani natives (Paraguay) credited with first
using the dried leaves to sweeten yerba mate (Ilex paraguariensis) & chewed the fresh leaves
Natives used orally delivered concoctions as a contraceptive, to manage diabetes, and to treat stomach aches
Caá hê-é or Kaà heè, which in Guaraní, a local dialect, translates into “sweet herb”
Lack of cultural & written records of stevia
Stevia rebaudiana
Ethnobotany cont.3 explanations for limited historical record
1. Sweet-tasting properties were known since the beginning of time, but kept a secret2. Natives shared plant with Spaniards, but the knowledge was disregarded or overlooked3. Stevia’s potential as a sweetener was not discovered by natives until only a short time before European contact
Stevia rebaudiana
Figure 4: Paraguayans harvest stevia.
Chemistry Active compounds: group of diterpene
(steviol) glycosides dulcoside A, rebaudiosides A-E ,
steviolbioside, & stevioside Rebaudioside A (3.8%) and stevioside (9.1%)
are the sweetest, most abundant, & most important commercially
Highest yield of these compounds in leaves just before the plant begins to flower,
Stevia rebaudiana
Chemical structure of stevioside (left) and rebaudioside A (right)
Stevia rebaudiana
Chemical structures
Extraction & Commercial Uses Processing of dried leaves from Stevia
produces a powdery white substance (stevioside), which is three hundred times sweeter, by weight, than sucrose derived from sugar cane
Water extraction process followed by crystallization techniques to isolate the steviol glycosides
NRC has patent on nanofiltration techniquescommercially available stevia products:
stevioside and rebaudioside A include Truvia, Fructevia, Krisda, & PureVia.
Stevia rebaudiana
Commercial products
Stevia rebaudiana
Nutrition The dried leaves are 30 to 45 times as sweet
as sucrose Non-nutritive, three hundred times sweeter
than sugar, heat stable, non-fermentable, as well as an anti-plaque and anti-carie
More studies must be conducted on bulking agents to make it easy to replace it for sugar
Stevia rebaudiana
Traditionally, North America & EU have only permitted use of highly purified extracts for sale in health food stores & pharmacies
Leaves classified as a dietary supplement, but not as a sweetener (Health Canada 2011)
FDA & Health Canada has approved use of stevia derivatives as a sweetener in some products (FDA 2011; Health Canada 2011)
Marketed as medicinal, non-medicinal ingredients & for personal culinary use
RegulationStevia rebaudiana
Controversies Few conclusive results verifying negative
health claims Investigated effect of stevia on energy &
carbohydrate metabolism, on the cardiovascular & renal systems, & reproduction
Diabetes mellitus: helps with proper blood glucose control, as antihyperglycemic by stimulating the release of insulin, & to help prevent insulin intolerance in diabetic patients
Need for further clinical trials to ensure safety of stevia for widespread human consumption
Stevia rebaudiana
Stevia rebaudiana
Questions
ReferencesGoyal, S. K., Samsher, and Goyal, R.K. 2010. Stevia (Stevia rebaudiana) a bio-sweetener: a review. Intl. J. Food Sci. and Nutr. 61(1): 1-10. Guens, J. C. 2003. Stevioside. Phytochemistry. 64(5): 913-921.Health Canada. 2011. Frequently Asked Questions "FAQs" on Stevia [online]. Available from http://www.hc-sc.gc.ca/. [accessed 10 March 20111].Huxtable, R. J. 2002. Pharmacology and toxicology of stevioside, rebaudioside A, and steviol. In Stevia: The genus Stevia. Edited by A. Douglas Kinghorn. Taylor & Francis Inc, New York. pp. 160-177. Jeppesen, P. B., Gregersen, S., Rolfsen, S. E. D., Jepsen, M., Colombo, M., Agger, A., Xiaso, J., Kruh, M., and Hermansen K. 2003. Antihyperglycemic and blood pressure-reducing effects of stevioside in the diabetic Goto-Kakizaki rat. Metabolism. 52: 372-378.Kinghorn, A. D. 2002. Overview. In Stevia: The genus Stevia. Edited by A. Douglas Kinghorn. Taylor & Francis Inc, New York. pp. 1-17. Krisda Canada. Product Information [online]. Available from http://www.krisda.ca/. [accessed 10 March 2011]. Lewis, W. H. 1992. Early uses of Stevia rebaudiana (Asteraceae) leaves as a sweetener in Paraguay. Econ. Bot. 46: 336-340. Madan, S., Ahmad, S., Singh, G. N., Kohli, K., Kumar, Y., Singh, R., and Gard, M. 2010. Stevia rebaudiana (Bert.) Bertoni – A Review. Ind. J. Nat. Prod. 1(3): 267-286. Rolfes, S. R., Pinna, K., and Whitney, E. 2009. Understanding Normal and Clinical Nutrition (8th ed.). Wadsworth, Cengage Learning, CA, USA. pp. 136.Samuelsson, G. 1992. Drugs of Natural origin. Swedish Pharmaceutical Press, Origin Stockholm Sweden.Shi Qiu, Z., Ashwani, K., and Oleh, K. 2000. Membrane-based separation scheme for processing sweeteners from stevia leaves. Food Res. Int. 33: 617-620.Soejartoa, D. D. 2002. Botany of Stevia and Stevia rebaudiana. In Stevia: The genus Stevia. Edited by A. Douglas Kinghorn. Taylor & Francis Inc, New York. pp. 18-39. Soejartob, D. D. 2002. Ethnobotany of Stevia and Stevia rebaudiana. In Stevia: The genus Stevia. Edited by A. Douglas Kinghorn. Taylor & Francis Inc, New York. pp. 40-67. Strauss, S. 1995. The perfect sweetner? Technol. Rev. 98: 18-20.Sumida, T. 1980. Studies on Stevia rebaudiana Bertoni M, introduced from Brazil as a new sweetness resource in Japan. J. Cent. Agric. Exp. Stn. 31: 1-71.The National Geographic Society. 2008. Edible: An Illustrated Guide to the World’s Foods Plants. Global Book Publishing, Washington, DC. pp. 333.United States Food and Drug Administration (FDA). 2011. What refined Stevia preparations have been approved by FDA to be used as a sweetener? [online]. Available from http://www.fda.gov. [accessed 10 March 2011].United States Patent and Trademark Office. 1998. United States Patent: 5,972,120 Extraction of sweet compounds from Stevia rebaudiana Bertoni [online]. Available from http://patft.uspto.gov/. [accessed 10 March, 2011]Wheeler, A., Boileau, A. C., Winkler, P. C., Compton, J. C., Prakash, I., Jiang, X., and Mandarino, D. A. 2008. Pharmacokinetics of rebaudioside A and stevioside after single oral doses in healthy men. Food Chem. Toxi. 46: 54-60.
Stevia rebaudiana