Blame it on the TAS2R38 gene. By almost a 2-to-1 ratio, the so-called 'taste gene' can determine whether children prefer the milder milk or high-sugar carbonated soft drinks as their go-to drink. High-fibre bran cereal or chocolate-frosted sugar bombs.1 Once children grow to adults, however, the TAS2R38 gene's influence on taste receptors encoded on the tongue wanes, and the prime determinants of one's sweet tooth bow to cultural forces, gender, race and experience.2,3
The childhood experience, say, of walking past a phalanx of high-sugar cereals lining the bottom shelves of supermarkets.
As American waistlines grew we began to beat the bushes for culprits. Sugar was an easy target, implicated as it is with obesity, diabetes and tooth decay.4 The food industry has responded over the last few decades by unveiling sweeteners that offer sugar's taste sans calories. Saccharin and aspartame were the leaders, followed more recently by acesulfame potassium (ace-K) and sucralose. Their main delivery systems have been in diet soda, sugarless gum and table-top single-serve packets.
Sucralose sales have skyrocketed since it was approved in the US in 1999, holding north of 60 per cent market share in the $1.5 billion artificial-sweetener market.5
But persistent Internet-fed safety issues surrounding alternative sweeteners, along with the health halo around all things 'natural,' have inexorably led the search for a true natural sweetener. Splenda brand sucralose owes much of its success to fraudulent inferences of being natural — chlorine is on the periodic table, making it natural, right?
Sucralose's natural gambit is up, but that doesn't mean manufacturers are acting with absolute integrity: In January 2010, Heartland Sweeteners received criticism from the National Advertising Division on its Ideal No Calorie Sweetener product, which promotes front-of-package icons touting "More than 99% Natural." Trouble is, although 99 per cent of the product weight may be natural, 80 per cent of the sweetness comes from non-natural sucralose. The advertising group has no regulatory authority to mandate marketing changes, so it remains to be seen what Heartland does.
The natural wars have allowed sugar to gain some of its groove back, but today we have the Reb-A revolution, with the promise of a bona-fide all-natural sweetener, based on the Paraguayan plant stevia. Should the sucraloses of the world be shaking in their boots? Yes, they should be. Should the sugar lobby be skittish as well? Not so fast. Stevia doesn't exactly have all the flavour issues all figured out, making blends de rigeur. And the top blending agent for Reb-A may be sugar. Companies are offering reduced-calorie sugar (20 per cent less seems to be the starting point) with these blends.
Even so, the natural-sweeteners story hardly starts and ends with stevia. But we'll start there.
What it is: Originally found in Paraguay (though about 80-90 per cent of today's commercial crop is grown in China), Stevia rebaudiana Bertoni is a small plant vaguely resembling mint whose leaves are eight-10 times sweeter than sugar. In Japan, for 30 years stevia-leaf extracts have been used as alternative sweeteners in everything from carbonated drinks to soy sauce. In the US, the FDA allowed it as a new dietary ingredient only for supplements in 1982, but denied GRAS status in the late 1980s and early 1990s. US GRAS no-objection letters, which started thanks to a Cargill/Coca-Cola partnership, have opened the market around the world. Europe has not approved it yet except in France and Switzerland, but is expected to do so in 2011.
Within the stevia leaves are 11 steviol glycosides — a molecular sugar group bonded to a nonsugar group. These are all sweet, yet most of them contain a lingering bitter aftertaste. Rebaudioside A (Reb-A) has been selected by food scientists as the best of the crop. The purified version is about 300 to 350 times sweeter than sugar.
Reb-A products must be a minimum of 95 per cent of any of seven designated steviol glycosides in any ratio (though stevioside and Reb-A remain most common). Most fall in the range of between 98 and 99.5 per cent Reb-A.
Pros: The market opportunity for stevia is huge. 'All natural' was the top claim for new product launches in 2008, according to ACNielsen. There is a declining consumer interest in the current sweetener alternatives, and a growing interest in natural. Stevia has a glycaemic index of 0 and does not affect blood-sugar levels. It's the perfect all-natural solution for consumers looking to manage their weight by cutting sugar calories from their diets. It performs well with heating and freezing and is pH-stable.
Cons: Cost and taste could be limiting factors. However, while its cost is currently more than sugar, by the end of 2010, it is expected to be cheaper than sugar, thanks to an explosion of hectares planted around the world.
Safety issues are a wild card, as they have been with every sweetener ever introduced. Paraguayan folklore holds that the plant can be used to avoid pregnancy. A 1968 study published in Science found a water decoction of the plant reduced fertility in adult female rats of proven fertility.6 However, a follow-up study in 1991 on hamsters with a range of doses from 0 to 2.5g/kg body weight per day found no effects on either growth or reproduction.7
Stevia leaf has been documented to have a hypotensive, or blood pressure lowering effect, though at dosages higher than used for sweetening purposes. A two-year human clinical trial on 168 Chinese patients found 500mg three times daily led to significant decreases in blood pressure, which began about one week after the start of the treatment and continued throughout the study. Quality of life also improved.8
At dosages higher than used for sweetening purposes, stevia has been documented to have a hypoglycaemic effect. Indeed, in a human clinical trial on 12 type 2 diabetic patients, 1g/day stevioside with a test meal reduced blood-glucose levels post-meal compared to a corn-starch control group.9
Formulation tip: Not all Reb-As are the same, so you'll have to really do your due diligence. One difference is the purity percentage — there's a difference between 97 and 99 per cent. But the key to superior taste is not necessarily the degree of rebaudioside purity, says Mel Jackson from Reb-A supplier Sweet Green Fields, but what is removed and how it is removed in the extraction and purification process, which differs among suppliers. Some extraction processes use water and ethanol, the latter of which is removed from the final product. Others use methanol and other toxic solvents.
Reb-A can be used to replace sucrose, high-fructose corn syrup or other artificial sweeteners. Because Reb-A is so much sweeter than what it replaces, formulators will need to take advantage of inert fillers such as inulin, maltodextrin, erythritol or fructose.
Blends will differ depending on the application. Greg Horn at Wild Flavors recommends mixing with erythritol in beverages, for example, and xylitol and mannitol in confectionery.
Masking agents may also be required for Reb-A's slight bitter notes. No single masking agent works for every Reb-A food and beverage application — formulation changes, processing fluctuations and age-related changes in some foods and beverages will keep formulators on their toes. For example, Coca-Cola France reformulated its Fanta carbonated soft drink with stevia because noncandy citrus flavours can mask and complement the bitter notes of Reb-A. But obviously citrus flavours are not the answer for every food-based Reb-A application. And some companies assert they have stevia taste issues nailed without masking agents or taste enhancers.
"A focus on purity should nullify flavour issues because Reb-A tastes better than stevia extracts of the past," said Cecilia McCollum, executive vice president of Blue California, which supplies the Good & Sweet Reb-A brand ingredient.
Reb-A is pH-stable. Short-term thermal processing tests of stevia extracts at pH levels ranging from 3.2 to 6.5 in conditions typically used in pasteurisation found less than one per cent loss of Reb-A, according to Horn. Similarly, good stability findings were reported for light and heat conditions.
As with all high-intensity sweeteners, it gives a thin mouthfeel.
Did we mention the slight bitterness and potential licorice off-notes?
Products served: Reb-A appeared first in diet soft drinks and tabletop sweeteners. Yoghurts, milk, ice cream, juice, tea, chocolates and cookies are also riding the bandwagon.
Bonus: In the 1990s, a project in Bolivia found that stevia could be a replacement crop for farmers who currently grow drug-producing plants (read: cocaine), according to James A May, Sr, founder of Wisdom Natural Brands, manufacturer of SweetLeaf Sweetener brand stevia. Stop the war on drugs — plant stevia!
What it is: Erythritol is a natural, non-caloric sweetener classified as a sugar alcohol. It is a bulking sugar replacement added to foods and beverages and often used to accompany high-intensity sweeteners in blends. It provides sweetness and also enhances taste and texture. Although its relative sweetness is debated, with it purported to be as much as 70 per cent as sweet as sugar, "in practical use it's about half as sweet as table sugar," asserts Tim Avila, general manager of Zero Worries Foods Inc, makers of ZSweet brand erythritol. "The literature varies. I've been using it since 1997. It's not as sweet as 70 per cent — maybe on its best day, powdered into a fine powder."
Erythritol has been part of the human diet for thousands of years as it is present in fruits such as pears, melons and grapes, as well as foods such as mushrooms and fermentation-derived foods such as wine, soy sauce and cheese.
Pros: Erythritol is naturally made, by fermentation from sugar. It has a lower glycaemic index than other bulk sweeteners in its class, such as xylitol or maltitol. It's a good building-block bulking ingredient, and is used in particular to make blends with Reb-A.
"Zerose erythritol and Truvia rebiana are not competitive products," said Cargill's Pam Stauffer of the company's branded sweeteners. "They are complementary ingredients and work great together in many naturally positioned products that are important to consumers, such as tabletop sweeteners, beverages, bakery and confections, to name a few."
Cons: It lowers the temperature in the mouth, which gives it a cooling, minty effect. This is fine if you're making mint chocolate or certain flavours of sugar-free gum. "I'm surprised it's not in more oral-care products like toothpaste and sugar-free gum," says Avila. But that is a limitation in other foods and beverages. Because it does not dissolve in water like sugar does, it cannot be made into a thick corn syrup-type sweetener.
Formulation tip: It functions like granulated sugar. Its limitation is solubility.
Products served: Table-top sweeteners are a natural. A much greater opportunity exists in sugar-free gum, a category which up to now has been dominated by xylitol and sorbitol. Frozen products like ice cream, as well as juices and teas, round out the food apps.
Bonus: Erythritol occurs in nature — it was discovered that organisms cohabitating in honeycombs with bees convert some of the natural sugars in honey to erythritol. If bees can do it, you can do it.
What it is: Derived from the agave plant, a spiky-leafed member of the lily family, the plant is often mistaken for a cactus. It is the cause celebre of sweeteners. "It is mostly fructose (fruit sugar), so it's lower than sugar and honey on the glycaemic index," says Christine Gerbstadt, MD, RD, a certified diabetes educator in Sarasota, Florida, and spokeswoman for the American Dietetic Association.
Pros: Agave can score 17 (on a scale of 1 to 100) on the glycaemic index, which measures the rate at which a carbohydrate is absorbed into the bloodstream. However, its GI score fluctuates depending on the product application. Also, different brands of agave contain different amounts of fructose vs glucose. It is generally seen as being about 1.3 times as sweet as sugar.
Cons: It is lower on the GI index than sugar, but higher in calories and otherwise has no nutritional value.
Formulation tip: Great browning properties. A high freezing-point depression, which lowers the temperature at which something freezes, makes it excellent for ice cream.
Products served: Agave can be used in beverages as a straight-up sweetener. In all other applications, agave has other properties, from also being a humectant in bars to being a browning sugar in confectionery, baked goods and sauces.
Bonus: The fermented juice of the blue agave plant is used to create tequila.
What it is: Derived from sprouted brown rice fermented with enzymes to disintegrate the starch content, the syrup has a honeylike consistency and a mild flavour.
Pros: Mostly a complex carbohydrate, brown-rice syrup breaks down slower in the body than sugar and thus provides a steadier supply of energy. It also has fewer calories than sugar. "It's only 20 per cent as sweet as sugar, but it does have a better effect on your body," says Mona Morstein, ND, chairwoman of nutrition at Southwest College of Naturopathic Medicine in Tempe, Arizona. "It has a nice mellow, almost vanilla flavour."
Cons: It is only slightly lower than sugar on the glycaemic index.
Formulation tip: It can be used like honey, molasses and other liquid sweeteners. In processed foods, brown-rice syrup gives a nice browning effect as well as superior binding capabilities, which can be useful in bars. It also contains added nutritional benefits from the rice, including protein and B vitamins. Depending on the enzymes used in the fermentation process, the brown-rice syrup can be made to be gluten free.
Products served: Cereals and bars. It can also be offered as a powder, which expands its potential applications.
1. Mennella JA, et al. Genetic and environmental determinants of bitter perception and sweet preferences. Pediatrics 2005 Feb;115(2):e216-22.
2. El-Sohemy A, et al. Nutrigenomics of taste - impact on food preferences and food production. Forum Nutr 2007;60:176-82.
3. Hayes JE, Duffy VB. Oral sensory phenotype identifies level of sugar and fat required for maximal liking. Physiol Behav 2008 Sep 3;95(1-2):77-87.
4. Palacios C, et al. Nutrition and health: guidelines for dental practitioners. Oral Dis 2009 Sep;15(6):369-81.
5. Browning L. "Makers of Artificial Sweeteners Go to Court," New York Times Business section, April 6, 2007.
6. Planas GM, Kucacute J. Contraceptive properties of Stevia rebaudiana. Science 1968 Nov 29;162(3857):1007.
7. Yodyingyuad V, Bunyawong S. Effect of stevioside on growth and reproduction. Hum Reprod. 1991 Jan;6(1):158-65.
8. Hsieh MH, et al. Efficacy and tolerability of oral stevioside in patients with mild essential hypertension: a two-year, randomized, placebo-controlled study. Clin Ther. 2003 Nov;25(11):2797-808.
9. Gregersen S, et al. Antihyperglycemic effects of stevioside in type 2 diabetic subjects. Metabolism. 2004 Jan;53(1):73-6.