New and Emerging Opportunities for Plant-Derived Sweeteners

by Rachel Wilson

The global market for intense sweeteners is experiencing steady growth, as a result of the continuing consumer trend toward reduced sugar intake; in 2009, the world market for intense sweeteners was worth more than $1.27 billion.¹ However from a technical point of view, intense sweetener products are undergoing a period of radical change. Having traditionally been dominated by products such as aspartame, acesulfame K and saccharin, their position may be coming under threat as the trend toward all things natural continues.

Consumers are increasingly choosing products that claim to be natural or contain all-natural ingredients and, to that end, sweeteners derived from plant sources are likely to be viewed favorably by developers, retailers and consumers alike. The key natural sweeteners from the industrys point of view are steviol glycosides, monk fruit or luo han guo, thaumatin, glycyrrhizin and, in the future, most probably monatin.²

Stevia

Stevia rebaudiana Bertoni is a member of the chrysanthemum family that grows wild in Paraguay and parts of Brazil.³ The native populations of South America have used extracts from these leaves for sweetening bitter tasting beverages for many centuries.⁴ Stevia leaves contain a group of seven or eight highly potent, zero-calorie sweet compounds, collectively known as steviol glycosides.

It is the Stevia rebaudiana extracts that are commonly used in commercially available stevia products with different levels of purity being available, ranging from 10-percent purity to 90-percent purity.⁵ The primary extract is rebaudioside A also known as rebiana or reb A and has a sweetness between 200 and 400 times that of sugar depending on concentration and application. It is suitable for use in a range of applications including low-pH carbonated beverages and dairy beverages, and it can also withstand the high temperatures reached in processes such as pasteurization or UHT. For this reason, reb A offers good potential to the bakery industry as well as applications such as dairy, soft drinks, desserts and sauces. It is most stable between pH 3 and 8, with a noticeable lessening in stability at pH less than 2. Although overall stability does decrease with temperature of storage because the breakdown products of reb A are also steviol glycosides, they are also sweet and therefore the loss in sweetness in negligible.  Reb A is synergistic for sweetness with cyclamate and aspartame, and has been shown to enhance fruit flavors and salt-free seasonings.⁶

PureCircle was the first to successfully develop a specific sweet compound from stevia leaves, known as rebaudioside A (reb A) or rebiana. This extract has since been commercialized as Truvia® by a Cargill/Coca-Cola partnership and as PureVia® by a Pepsico and Merisant partnership.

Stevia represents one of the most dynamic sectors within the global intense sweeteners market, with sales having risen dramatically since the middle of the last decade as a result of increasing uptake within the U.S. food and drinks industry.

In 2009, global market value reached an estimated $175 million, up from just $10 million in 2005. Much of this increase has come from the United States, although it seems likely that Europe will assume increasing significance once EU approval is granted, possibly later in 2011.

Monk Fruit

Siraitia grosvenorii (also known as luo han guo) is a perennial vine of the Cucurbitaceae family and is a traditional medicinal herb cultivated principally in the Guangxi region of China.⁷ Although inherently sweet, the fruit itself is unsuitable for use as a sweetener without additional processing, as it has a tendency to form off-flavors by fermentation.

The sweet taste of luo han guo comes mainly from the mogrosides, a group of triterpene glycosides. The mogrosides are present in total at about 1 percent in the flesh of the fruit.⁸ The most abundant triterpene glycoside component is mogroside V, which is reported to be approximately 300 times sweeter than sucrose.

Through extraction processes, a powder containing up to 80-percent mixed mogrosides can be obtained, which is approximately 250 times sweeter than sugar.⁹ The mogrosides are inert to thermal and enzymatic degradation of digestion and, subsequently, luo han guo is a biochemically stable, non-nutritive, non-hygroscopic and non-cariogenic product.¹⁰

A number of commercially available extracts of luo han guo are available such as Mormordica (Amax Nutrasource Inc., City of Industry, CA ) and Purelo (Biovittoria, Hamilton, New Zealand). These vary in mogroside content, but are typically 20-percent to 70-percent mogroside V and 40-percent to 90-percent total terpene glycosides.

In the United States, luo han guo juice or dried concentrate has been GRAS (generally recognized as safe) since early 2010 and is generally labeled as luo han guo fruit concentrate or monk fruit concentrate.

Luo han guo is not currently a permitted sweetener in the EU, although it may be used as a natural flavor preparation at concentrations where it does not function as a sweetener. It is likely manufacturers will seek EU approval for luo han guo juice concentrate as a novel food and for the powdered product as a food additive in the next few years.

Glycyrrhizin

Glycyrrhizin is a characteristic sweet-tasting principle isolated from licorice, the root of some species of glycyrrhiza belonging to the family of leguminosae, and it has historically been widely employed as a sweetening and flavoring agent. Perhaps the first use of the licorice component as a food ingredient was in the 18^th century by an English chemist, who blended the licorice extract with sugar, molasses, flour and other ingredients to produce Pontefract Cakes (small, circular stamped cakes).¹¹ This use rapidly developed into the manufacture of many other confectionery products in Europe and the United States. In the early part of the 20^th century, licorice extract was applied successfully to soy sauce, where it was found to suppress the saline taste. Since then, the use of licorice as a sweetener has expanded to a number of salty foods, such as meat products and snacks.

The base products monoammonium glycyrrhizinate and ammoniated glycyrrhizin are approved for use in foods in the United States, Europe, Australia, China, India and numerous other countries throughout the world.

As well as a sweetener, licorice extracts and glycyrrhizin are affirmed GRAS by the Flavor and Extract Manufacturers Association (FEMA) for a wide range of flavoring uses in the United States.

Thaumatin

Thaumatin is the intensely sweet protein isolated from the fruit of Thaumatococcus daniellii, an African plant named in 1855 after Dr. W.F. Daniell.¹² The plant exists throughout the rainforests of West Africa, where it has been used for centuries to sweeten and improve the palatability of foods.

The fruit of Thaumatococcus daniellii contains a black seed surrounded by a polysaccharide mucilage. The upper seed cap is called an aril and this is where the thaumatin proteins exist. Large-scale production of thaumatin is achieved by aqueous extraction under low pH followed by other physical methods, thus preserving the natural status of the extract.¹³

The taste profile of thaumatin is quite different to that of sugar in that it has a delayed onset and a prolonged aftertaste. However, addition of thaumatin to products has been demonstrated to enhance overall sweetness in products as well as masking bitter aftertastes. This means thaumatin is commonly seen in combination with other intense sweeteners and is more often used for its flavoring properties as opposed to providing sweetness in its own right.

In the United States, it is approved by FDA as a GRAS flavor preparation for about 30 applications.

Monatin

Monatin is an amino acid isolated from the root bark of the plant Sclerochiton ilicifolius, which grows in South Africa. The root has long been known for its sweetness; however, the identification of monatin as the component responsible for the sweetness was first reported in 1988.¹⁴

Monatin has an excellent sweetness. In flavor profile, it is close to sucrose, with a quick onset, a clean sweet taste and no noticeable aftertaste. This combination of high sweetness and clean flavor suggests monatin could be used widely as a sole sweetener and need not be blended with otherssomething that is somewhat unique among plant-derived intense sweeteners.

Monatin has no commercial applications as of yet, and it does not have a regulatory status in the United States or European Union, but the patent literature highlights interest in the sweetener for use in a wide range of products including all types of beverages confectionery, dairy products, chewing gum and table-top sweeteners.

Future Trends

Demand for sweeteners is expected to continue its steady growth partly as a result of an increased dynamism in the sweetener industry, which is currently seeing a number of new options available after years of relative stability. The fact that a number of these sweeteners are from plant-derived sources is aligned with the current consumer trend toward all things natural, and this can only mean a positive future for these products.

The World Stevia Organization recently announced it is broadening its scope to include all-natural sweeteners, such as monk fruit, thaumatin and others whose potential is still being explored. This decision to include other plant derived sweeteners as well as stevia comes from the general agreement within the scientific committee that the future will see a combination of natural sweeteners being used.

Leatherhead Food Research is holding a two-day conference looking at new and emerging developments in plant-derived sweeteners on Oct. 18 and 19, 2011, at the Royal Horticultural Halls and Conference Centre in London.

Rachel Wilson is principal technical advisor on additives and ingredients at Leatherhead Food Research , where she specializes in providing information about food additives and ingredients, and conducting literature and patent reviews. She is editor of Sweeteners, 3rd Edition, 2007, Leatherhead Food International and Blackwell Publishing, Oxford, which forms part of Leatherheads range of Ingredients handbooks for industry. She has a bachelors of science in food science from Reading University, England, and a career spanning both product development and ingredients.

References are on the next page...

References for New and Emerging Opportunities for Plant-Derived Sweeteners by Rachel Wilson

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2. Fry J.C.  Natural low-calorie Sweeteners in "Natural Food Additives, Ingredients and Flavourings" Baines D., Seal R. (Eds), Woodhead Publishing, in press.

3. Yamaomoto K., Yoshikawa K., Okada S. Effective production of glycosyl-steviosides by alpha-1, 6 transglucosylation of dextrin dextranase. Bioscience, Biotechnology, and Biochemistry, 1994, 58 (9), 1657-61.

4. Teeuwen H.W.A. Outlook for high-intensity sweeteners. International Food Ingredients, 1991, 4, 4-9.

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6. Phillips K.C. Stevia: Steps in developing a new sweetener in Developments in Sweeteners 3, Grenby T.H. (Ed), London Elsevier Applied Science, 1987, 1-45.

7. Xia Y., Rivero-Huguet M.E., Hughes B.H., Marshall W.D. Isolation of the sweet components from Siraitia grosvenorii, Food Chemistry, 2008, 107, 1022-1028.

8.  Kinghorn A.D., Soejarto D.D., Sweetening agents of plant origin, Critical Reviews in Plant Sciences, 1986, 4(2), 79-120.

9. Kasai R., Nie R.L., Nashi K., Ohtani K., Zhou J., Tao G-D. Sweet cucurbitane glycosides from fruits of Siraitha siamensis (chi-zi luo-han-guo) a Chinese folk medicine, Agricultural and Biological Chemistry, 1989, 53(12), 3347-3349.

10. Marone P.A., Borzelleca J.F., Merkel D., Heimbach J.T., Kennepohl E. Twenty eight-day dietary toxicity study of Luo Han fruit concentrate in Hsd: SD®rats, Food and Chemical Toxicology, 2008, 46, 910-919.

11.  Muller R. E. Special properties of licorice need exploitation, Candy Industry and Confectioners Journal, 1964, June, 34-40.

12. Daniell W.F. Thaumatin - A taste modifying protein, Pharmaceutical Journal, 1855, 14, 158.

13. Lord J. Thaumatin in Sweeteners Wilson R. (Ed), Leatherhead Food International and Blackwell Publishing, 2007, 127. 

14. Van Wyk P. J., Ackerman, L. G. J. 1988. 3-(1-amino-1,3-dicarboxy-3-hydroxy-but-4-yl)-indole compounds. UK Patent GB 2 205 834 A