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The science of sweetener blends

By Stephen Daniells , 23-Sep-2009

Achieving the ideal sweetener blend is a scientific undertaking, making or breaking a product’s acceptance. In the second part of our special series on sweetener blends, FoodNavigator look at what makes a blend a success.

One of the most successful and widespread sweetener blends is acesulfame-K with aspartame. The blend is used in a range of products ranging from soft drinks to chewing gum. The sweeteners work in synergy, thereby allowing the blending of low concentrations of acesulfame-K, which can be bitter at higher concentrations, with aspartame, which doesn’t have the bitter components.

“The precise mechanisms that produce synergism among sweeteners are not known at the present time,” stated Susan Schiffman from Duke University in the Brain Research Bulletin (1995, Vol. 38, pp. 105-120). “However, it is probable that multiple receptors as well as multiple transduction mechanisms play a role.”

A list as long as your tongue

Many sweetener synergisms have been identified whereby the mixture produces a total sweetness with the sum greater than the parts. A relatively large range of sweeteners are available to achieve the ideal blend, including sucralose, neotame, mannitol, , acesulfame-K, sorbitol, saccharin, fructose, sucrose, cyclamate, stevioside, aspartame, rebaudioside-A (stevia), erythritol, neohesperidin dihydrochalcone (NeoDHC), alitame, and thaumatin.

Understanding how these sweeteners work, and whether they are ‘early’ or ‘late’ was the focus of a study by scientists from NutraSweet and Duke University in 2007 (Food Quality and Preference, Vol. 18, pp. 405-415).

"With the growing trend in the commercial market towards the use of sweetener blends in a variety of media, putting emphasis on designing a sweetener blend that yields the best possible temporal profile for a given medium is of increasing importance," they wrote.

Achieving the right blend

The researchers tried various blends and assessed the so-called "time to maximum sweetness" - a measure of how quickly the sweet taste is experienced in the mouth.

Three different sweetness levels were examined for each binary blend, and the blends were formulated to be equally sweet as 3, 5, and 7 per cent sucrose solutions.

Blends containing stevioside, neotame, NeoDHC, alitame, or rebauadioside-A had later times to maximum sweetness intensity compared to blends with sugars and sugar alcohols, reported the researchers.

It was also found that many of the blends displayed times to maximum sweetness intensity that were in-between the earliest and latest of its constituent parts.

Formulators would have additional variables to play with since additional data suggested that the time to maximum sweetness is further influenced by other ingredients in the beverage.

Zero-calorie plus zero-calorie

A discussion of sweeteners would not be complete these days without mention to stevia – the natural, zero-calorie sweetener making big waves around the world. McNeil Nutritionals, the company behind the sucralose-based Splenda, has filed a patent application for a stevia-erythritol blend to add to the multi-coloured sachet range of table top sweeteners.

According to the company’s application (US2008/068344), erythritol is currently blended with a range of other sweeteners including inulin, isomalt, and glycerin in order to counter erythritol’s ‘strong cooling effect’.

“However, all [of these sweeteners] add bulk, calories, and potentially gastro-intestinal side effects, all of which are undesirable attributes in a tabletop sweetener composition,” says the patent application. “What is needed is a tabletop sweetener composition that minimizes the erythritol's brightness without the calories and potential gastro-intestinal side effects associated with previously known methods.”

While some products are already available using erythritol and stevia (80 to 99 per cent Reb-A), most of these use a blend whereby stevia provides between 20 to about 75 per cent of the sweetness of the composition, claims the McNeil patent.

“Surprisingly, it has been found that erythritol-containing tabletop sweetener compositions containing very small amounts of stevia extracts unexpectedly mask the "bright" taste normal associated with erythritol,” states the patent application. “This effect occurs at levels that are about 300 times less than those previously known. The level is also several times less than compositions where stevia is the primary sweetener.”

This led the McNeil team to stevia, and they are developing a blend containing a weight ratio of about 200 to 2000 (erythritol) to about 1 (stevia). Such a formulation would mean that between 70 and 99 per cent of the sweetness would come from stevia, while 98.5 to 99 per cent of the weight coming from erythritol.

McNeil patent: http://www.wipo.int/pctdb/en/wo.jsp?IA=US2008068344&DISPLAY=STATUS