No non-caloric sugar substitute tastes exactly like sucrose. “Research into improving taste of sugar substitutes in beverages involves ten metrics,” explained Grant DuBois, Consultant, Sweetness Technologies, LLC. DuBois imparted this information in his presentation “Breakthrough Technology Dramatically Improves Sweetener Taste,” which was prepared for the 2020 Sweetener Systems Conference. He then gave insights into a new sweet taste modulator.
The following is an expanded version of that appearing in the 2020 Clean Label Post Conference Magazine.
Safety: The first metric is safety. The cost of developing a new sweetener could approach $100 million for going through the Food Additive Petition process or $20 million for the GRAS Self-Affirmation process.
Taste Quality, Maximal Response: Maximal response is the maximal sweetness intensity of a sugar substitute compared in sucrose equivalent units. As examples, the maximal sweetness intensity of saccharin is equivalent to 9.1% sucrose, cyclamate 18.4% sucrose, aspartame 24.7% sucrose and rebaudioside A (Reb A) 9.7% sucrose in water at ambient temperature.
Taste Quality, Flavor Profile: The next metric is the flavor profile or relative levels of sweetness, bitterness, licorice taste, mouthfeel, etc.. At a sucrose equivalency of 7%, saccharin has a lot of bitter taste and aspartame only a trace of bitterness. Reb A, at most commercial levels of purity (e.g., 97%), has some bitterness but significant licorice-like, off-taste. Ultra-high purity Reb A (e.g., 99.5%) has negligible licorice off-taste, but it is higher in cost.
Taste Quality, Temporal Profile: A major issue with non-caloric sweeteners is temporal profile, which is how quickly the sweetness rises and how long it lingers. At a maximal sweetness response equivalent to 7% sucrose, aspartame rises rapidly, but lingers significantly. Reb A comes on more slowly but lingers more than aspartame.
Taste Quality, Adaptation/Desensitization: Some sweeteners desensitize or cause adaptation of the sweetness sensory system. When tasting a beverage sweetened with HFCS 55, there is little or no change in response when iteratively tasting every 30 seconds. However, a beverage sweetened with aspartame was significantly reduced in sweetness with subsequent tastes, said DuBois.
Cost: In the beverage industry, the costs of ingredients are measured on a cost-per-unit case basis (cents/UC), where “UC” is a case of 24, 8oz bottles. The sweetener cost for a full-calorie HFCS sweetened beverage is approximately 54 cents/UC. In contrast today, the cost of the sweetener for a zero-calorie beverage sweetened with aspartame is approximately 3 cents/UC. Sweetening a diet cola beverage with Reb A today would cost some 34 cents/UC, but the taste would not be acceptable. For comparison, a blend of Reb A and erythritol would be acceptable in taste, but the cost would be around 90 cents/UC.
The last four metrics are “Solubility,” “Stability” (to hydrolysis and light exposure), “Patentability” and “Consumer Acceptance.”
One new approach in sweetness innovation technology involves enhancement of the normal sucrose response by action of a sweetener receptor positive allosteric modulator (PAM). PAMs allow significant reduction in sucrose concentration with retention of the good taste of sucrose. However, the maximal enhancement factor found with PAMs is 2-fold, and sucrose reduction is limited to ca. 50%. In addition, the only PAMs discovered are synthetic compounds and must be labeled as artificial flavors.
In the late 1990s, consumers began to demand all-natural ingredients. All-natural, non-caloric sweeteners, however, offered poor replication of sucrose taste and required taste modulators, the most common among them being erythritol and allulose. Problematical with natural non-caloric sweetener formulations with erythritol and allulose were high formulation costs. At that time, and still today, the commonly used synthetic sweeteners were aspartame; aspartame blended with acesulfame-K (ACE-K); and sucralose blended with ACE-K. Synthetic sweeteners were also being blended with full-calorie sweeteners.
As a consequence of consumer interest in natural food ingredients, the search was on for a sweetener that best met the 10 metrics for commercial viability. After consideration of 50 structural classes of natural non-caloric sweeteners, The Coca-Cola Company determined that the stevia sweetener REBA most closely met the 10 metrics. Reb A was GRAS self-affirmed in 2008 and received a “No objection” letter from the FDA in the same year. Subsequently, Reb D and Reb M were also GRAS self-affirmed.
Although the stevia plant is indigenous to Paraguay, most of the cultivation takes place in China. There are various quality and taste issues with the lower purity Reb A, and most of these have been overcome with a recently commercialized ultra-pure REBA of 99.5% minimum purity. This ultra-pure form is more expensive. However, agricultural technology is under development whereby very significant cost reduction.
Formulation research studies led to the hypothesis that the cause for the delayed onset of sweetness of Reb A, as well as its lingering sweet aftertaste, were slowed diffusion through the mucous hydrogel film covering the lingual epithelium. Thus, while sucrose and other carbohydrate sweeteners rapidly diffuse through the mucous hydrogel, non-caloric sweeteners like Reb A bind to hydrophobic sites in the mucous hydrogel and, thus, are delayed in reaching the sweetener receptors and are delayed in diffusing away from sweetener receptors.
This delay in egress from the receptors is believed to result in iterative activation of the sweetener receptors—a phenomenon perceived as sweetness linger. Our research led to the finding that formulation of REBA, as well as other noncaloric sweeteners, with a blend of K, Mg and Ca mineral salts, resulted in acceleration of sweetness onset as well as a marked diminution of sweetness linger. Our research suggests that the Mg and Ca mineral salts bind to sites in the mucous hydrogel, so as to create pores which allow more rapid diffusion of non-caloric sweeteners to and from the sweetener receptors.
In addition to the dramatic effects of such mineral-salt blends on non-caloric sweetener temporal profiles, we observed a very pleasant, sugar-like mouthfeel in these mineral-salt fortified formulations. The mouthfeel effect is believed to follow from activation of the Calcium Sensing Receptor, which Japanese scientists have recently demonstrated to be expressed by a subset of taste bud cells and to be responsible for kokumi taste, which is translated as “mouthfulness.”
Many K/Mg/Ca mineral-salt formulations have been found to be effective in both modulation of non-caloric sweetener temporal profiles, as well as introducing a very pleasant, sugar-like mouthfeel and KCl/MgSO4/Ca(Lactate)2 compositions were found particularly effective. This work is now covered by a 2020 U.S. patent.
Mineral-salt taste modulators work for all non-caloric sweeteners, both synthetic and natural. These taste modulators improve non-caloric sweetener temporal profiles very significantly; deliver sugar-like mouthfeel; and they are clean label, cost effective and GRAS, concluded DuBois. In addition, these mineral-salt taste modulators increase the sugar-like mouthfeel of carbohydrate formulations and, in effect, make sugar taste better than sugar.
“Breakthrough Technology Dramatically Improves Sweetener Taste,” Grant DuBois, Consultant, Sweetness Technologies, LLC, firstname.lastname@example.org