Optimizing Flavors and Sweeteners

By Cindy Hazen, Contributing Editor

Whether were talking economic or environmental issues, theres a common theme: We should do more with less.

The food industry can relate. Weve all heard consumers say they want a longer shelf life but no preservatives; natural, organic and artisan at low cost; full flavor and sodium reduction; and no added sugar without compromising sweetness.

We cant meet every consumer expectation in this space, but we can give you some tips to help you get the most out of your sweetener system.

First things first

Sweeteners dont look alike, taste alike or behave alike. Yet, theres a tendency to compare. Sugar, or sucrose, is the standard, because its familiar to us and, importantly, its sweet from start to finish.

Sweetness is measured in how quick and how long sweet lasts in your mouth," explains Laura Ennis, senior beverage innovation technologist, David Michael & Co., Philadelphia. This can be measured by a temporal sweetness profile. Different sweeteners are rated on their intensity over time, and these results can be plotted onto a graph. For example, crystalline fructose peaks very early and fades rather quickly, whereas sucrose peaks later and lasts longer, hence the reason that most chewing gums are accentuated with artificial sweeteners to keep the sweet profile lasting longer. Non-nutritive sweeteners tend to take the longest to peak and, therefore, lack this upfront sweetness."

Perception of sweetness occurs when a sweet molecule comes in contact with a sweet receptor in the taste bud. Protein conversions lead to depolarization of the cell, which then leads to a buildup of the ions within the cell and causes the neurons to perceive sweetness," says Richard Davidson, vice president, Hagelin Flavor Technologies, Inc., Branchburg, NJ.

When the receptor is saturated, more sweetness cant be detected. If you drink a soda and then eat a piece of candy, depending on how much sugar is in the candy, you cant taste the sweetness of the candy because youve already peaked the receptor. It cant detect any more sweetness. You get to a point of diminishing returns."

Sweetness can seem enhanced by mouthfeel. Perceiving more fullness in your mouth aids in sweetness perception," says Ennis. Fats and bases that coat the mouth can detract from sweetness."

In the search to reduce sugar consumption and to optimize sweeteners, the industry is trying to come up with a silver bullet that will trick the cell into thinking a molecule is more sweet than it actually is.

You can go the old-fashioned way and use a molecule that is sweet. Sometimes we use vanillin, ethyl vanillin or helioptropine," Davidson says. "Those are components that will make you perceive more sweetness, but unfortunately they also carry flavor characteristics. Vanillin is going to taste vanilla-like. Heliotropine is going to be more of a cotton candy type flavor. Caramel furanones add sweetness, but again, they are characterizing."

Flavor companies are developing molecules built to get the receptor to depolarize more rapidly to give a stronger sweetness perception without adding a flavor note. You want to act on the chemistry on the cell, not to induce the flavor response," Davidson says. Thats been the trick."

Artificial advantages

Nonnutritive sweeteners have proved popular for many decades. Zero calories is one benefit of non-nutritive sweeteners. Potency is another.

For example, aspartame is 150 to 200 times as sweet as sucrose. Aspartame is unique in that its taste profile is good enough to allow it to be used as a sole sweetener," says Ihab E. Bishay, Ph.D., senior director business development/application innovation, Ajinomoto Food Ingredients, Chicago.

Yet, compared to sucrose, aspartame has "slow onset of sweetness and leaves a lingering aftertaste." says Ennis. It is also not very stable to heat and shelf life." Its best at more-neutral pH because it undergoes hydrolysis when it is in high-acid or alkaline conditions.

Aspartame is composed of two essential amino acids, L-phenylalanine and L-aspartic acid, and a methyl ester. When heated, aspartame has a tendency to break down to phenylalanine and aspartic acid.

Acesulfame-K (acesulfame potassium) also has issues with heat stability; however, its more stable than aspartame. At 200 times the sweetness of sucrose, it gives an early onset of sweet, but it can leave a bitter aftertaste. This is especially true at high concentrations.  Aspartame and acesulfame-K are often used together at 50/50 or 60/40 levels, respectively, depending on the end product. Their synergy together covers the entire sweetness curve," says Ennis.

Advantame, derived from aspartame and vanillin, is a new sweetening ingredient developed by Ajinomoto. Bishay says it does not have any synergies with high-potency sweeteners. Advantame has a similar stability profile to aspartame, but is more stable than aspartame under higher temperature and higher-pH conditions." In general, 4.5 is considered a higher-pH condition, but he notes all formulations are unique.

This powerful molecule is 20,000 times as sweet as sugar and about 100 times as sweet as aspartame. Currently, it is awaiting FDA approval as a sweetener. The FEMA (Flavor and Extract Manufacturers Association) expert panel, FEXPAN, has so far given it GRAS approval as a flavor enhancer in very specific applications at maximum ppm usage levels.

Allowable finished product levels of advantame are: 2 ppm in nonalcoholic beverages; 1 ppm in milk products, 1 ppm in frozen dairy products and 50 ppm in chewing gum.

If you go above that ppm you are deemed to be sweetening the product," explains Skip Rosskam, president, David Michael & Co., who's company is working with Ajinomoto to evaluate their new molecules that may have flavor modification or enhancement affect.

What we found, when compared to sweetness profile of sucrose, was that advantame had some gaps," Rosskam notes. "Normally, there is a bell-curve effect with sucrose. We observed that advantame started well, lost a little bit before hitting the peak, went back up again and, as it finished, we found a slight aftertaste. So, we engineered a flavor that allowed advantame to fill in the gaps, achieve a rounded profile and eliminate any aftertaste. We learned that by putting these two products together we could modify the sweetness profile in three of the four categories." Only chewing gum is excluded.

Both products are being used in some school-lunch programs. Weve engineered chocolate milk with a 25% calorie reduction," Rosskam says. Typical chocolate milk might be made with cocoa, a stabilizer like carrageenan, 6% high fructose corn syrup (HFCS) and an artificial flavor. We would take that same formula and reduce the sweetener HFCS by 25%," he says. "We would then add the advantame at no more than what is allowed in milk products, which is 1 ppm along with our flavor."

Sucralose is a powerful sweetener that can be used alone or in combination with other sweeteners. This chlorinated sugar compound delivers 400 to 600 times the sweetness of sucrose. Davidson says sucralose is probably one of the best at mimicking sugar in terms of time intensity."

Ennis finds it lacks mouthfeel, and its sweetness can linger. It can be difficult to work with in the powder form, and is expensive, which is why many times it is used in combination with other nonnutritive sweeteners such as aspartame and acesulfame-K." 

In the absence of a sweetener that is identical to sucrose, the answer lies in creating a combination with them," says.Mariano Gascon, vice president, R&D, Wixon, St. Francis, WI. "Because each application is very specific, there's not a single combo mix that works all the time. Fats play a significant role in any flavor perception, so be aware of its effect. Also, keep in mind that a combination can create a synergistic effect, but other sensory effects like suppression or fatigue would apply. If you found the right combo to simulate onset of sucrose in your product but there is some bitterness or lingering effects, use taste modifiers at that point."

Sugar alcohols

Like other bulk sweeteners, polyols exhibit more of a direct relationship between sweetness level and concentration," says Ron Deis, Ph.D., director, global sweetener development, Ingredion Inc., Westchester, IL. What can affect the overall sweetness profile are solubility, level of sweetness versus sucrose, and heat of solution. Many polyols have a more negative heat of solution, exhibited as a cooling effect in the mouth as their crystalline structure melts. Erythritol and xylitol have a very notable cooling effect."

Depending on the type of polyol, the cooling effect varies. All of them have a clean, sweet, but weak, taste," says Gascon.

Xylitol is the sweetest and approximates sugar with 100% the sweetness of sucrose. Erythritol is about 70%, and maltitol has 80%. Mannitol (50% as sweet) and sorbitol (60%) require a laxation claim in accordance with Title 21 of the Code of Federal Regulations, Part 180, Section 25(e).

Deis says that, in the past, polyols have only been thought of in the context of sugar-free applications. As formulators try to reduce calories, sugar and glycemic response in applications, polyols should be a part of the thought process," he says. 

Polyols are low-molecular-weight, low-digestible carbohydrates (LDC) with many similarities to fiber and prebiotics. Maltitol, maltitol syrups and polyglycitols are very similar in molecular weight to sugars and corn syrups, and can replace them in many applicationsparticularly in many confectionery, dairy and bakery applications," Deis says. "If reduced calories and reduced sugar are the goals, these polyols should be a part of the formulation plan. Maltitol and maltitol syrups also can work well with stevia or other high-potency sweeteners to achieve a good sweetness profile in dairy beverages, confectioneries and baked goods, while erythritol has been used with stevia in beverages and all-natural applications."

Corn sugars

Like other bulk sweeteners, high-maltose corn syrup (HMCS) and HFCS exhibit a direct relationship between sweetness level and concentration in a concentration-response curve," says Deis. Maltose is about 30% the sweetness of sucrose, and glucose about 60%, so a high-maltose syrup will be less sweet than a regular corn syrup. However, the unique sweetness and flavor profile of a high-maltose syrup makes it a favorite of confectioners when it can be used."

Two HFCS products are available to manufacturers: HFCS 55 is 55% fructose and 45 % glucose, and HFCS 42 is composed of 42% fructose and 58% glucose. HFCS 55 has the same relative sweetness as sugar.

Sucrose is a disaccharide made of fructose and glucose units bonded together. HFCS also contains fructose and glucose, but they are monosaccharides. They are free sugars," explains John S. White, Ph.D., nutritional biochemist and president, White Technical Research, Argenta, IL, scientific consultant to Corn Refiners Association (CRA).

Though virtually indistinguishable from sugar in terms of sweetness, the trained taster may pick up slight differences even with HFCS 55. Sugar would give you a broad peak," explains White. We would see an initial rapid peak from the fructose, which would decay rapidly, and right behind that, a little bit later in time but before the peak of sucrose, we would see a shorter peak for the glucose. Now the fructose peak would have a value of 117 in comparison with 100 for sucrose. Its a very sharp peak. It builds quickly and decays rapidly. Then thats followed by the glucose peak, which is much lower than sugar, about 62. Sometimes its given a range between 60 and 70. It builds more slowly than fructose does, but more quickly than sucrose, and then it declines as the sucrose peak is building."

The broad sweetness peak of sucrose tends to mask some flavors in the system. You get more of them with the HFCS because of the faster build and faster decline of sweetness. You can get enhanced fruit and spice flavors with HFCS that are masked by sucrose," White says.

HFCS offers flavor stability in low-pH applications like soft drinks, which have an average pH of 3.5. In a sucrose or sugar-sweetened beverage, the bond between the fructose and glucose is hydrolyzed by acid," explains White. This process starts immediately after bottling and continues until it is consumed by the purchaser. The warmer the temperature of storage, the faster this inversion takes place. The more hydrolysis that takes place, the more this sugar-sweetened product comes to resemble HFCS as this free fructose and free glucose is liberated. The concentration of those goes up and the concentration of sucrose goes down."

If youve ever heard someone express a preference for Mexican cola because its sweetened with sugar, you know now that there may not be much sugar left in that product when it reaches your friend to drink," White says. Your friend is drinking a product that very closely resembles HFCS in terms of its composition."

Diet soft drinks may not appeal to consumers who prefer traditionally sweetened beverages, because one of the things sugar and HFCS bring to the party is mouthfeel. When regular cola drinkers switch to diet, they say the problem is its too watery," says Davidson. The ones who like diet may say, 'I dont like the diet taste but I cant drink full sugar because its too syrupy.'"

 Replacing missing solids is one of the challenges of using high-intensity sweeteners. Diet drinks might be sweetened with as little as 0.01% solids. However, sweetener solids in a traditional soft drink are about 10%. If you were to make a 10% solids syrup-sweetened water and you took a drink of that you would notice sweetness but you would also notice the viscosity," says White. In terms of mouthfeel, its the viscosity of the liquid. Your tongues pretty sensitive to that."

High intensity, naturally

Some consumers and manufacturers are looking for zero calories in a natural package. Enter stevia, a group of sweetener ingredients derived from naturally occurring glycosides in the stevia plant. Compared to sugar, relative sweetness of these glycosides varies, as does flavor.

All of the steviol glycosides, and in fact many high-potency sweeteners (both natural and synthetic), have some degree of bitterness associated with their flavor profiles," says Deis.

Rebaudioside A (reb A) is about 400 times sweeter than sugar. It is one of the least bitter steviol glycosides, but still has a flavor profile which limits the total sugar equivalence that can be replaced," Deis says. "In most cases, it is not a stand-alone sweetener. That being said, we have learned a lot about what other ingredients work well with stevia and in which applications it works very well. We have had a lot of success in dairy applications, such as flavored milks, smoothies and yogurts. Stevia pairs well with nutritive sweeteners, such as sucrose and fructose, some fructose-based ingredients, such as agave sweetener and short-chain FOS, as well as certain flavor componentsall of which affect the overall sweetness profile in the application system. We are continuing to build a database on ingredients which enhance or modify the sweetness profile of stevia, and we apply this database according to the formulation and to the claims desired in the final product."

Deis describes Ingredions naturally-derived reb A stevia sweetener as having a very clean taste profile. Because its produced from a single proprietary cultivar, lot-to-lot consistency is assured. This is important, because once the finished products flavor is developed, food manufacturers dont want to reformulate to adjust for off flavors, sweetness intensity or overall taste profiles that can change if different stevia varieties are used or if extracts are sourced from several locations.

 There is no particular component of stevia contributing bitterness," says Deis. The science of bitterness taste receptors is less understood than that of sweetness taste receptors, except for the fact that there are many more bitterness receptors than sweet receptors."

It doesnt take many bitter-inducing compounds to make the product taste bitter. The threshold for the recognition of sweetness is detectable in 1 part in 200 parts of sucrose," explains Davidson. Bitterness is perceptible in 1 part per 2 million parts. The problem is, once you detect the bitter, it becomes very difficult to detect sweet."

This can be a problem with formulating with stevia. Weve done studies here where weve ratcheted up the levels to get to the point where its too sweet," Davidson says. "You cant do that. When you get to the point where its ostensibly too sweet, then you find out that its too bitter as well."

Rather than working to enhance the sweetness of stevia, his company has worked to modify bitterness.

Monk fruit sweeteners, extracted from the fruit of Straia grosvenori, are another naturally derived high-intensity option with 150 to 200 times the sweetness of sucrose. Like stevia, components within the plant vary in sweetness. Monk fruit, also called luo han guo, contains five different mogrosides (II, 111, IV, V and VI). Mogroside V is the sweetest. Only 0.5% to 1.5% extractable mogrosides are present in the dried fruit, so its been more expensive than stevia. But, just because an ingredient is currently more expensive, it doesnt mean that the cost per use is more expensive, especially if additional flavors arent needed. The flavor of monk fruit is more neutral than stevia, though it is sometimes described as having a slight note of melon rind.

Besides cost, label claims and nutritional panel targets should be considered. Its important to explore what sweetener types work best for each flavor profile and application. Marie Cummings, manager, food applications and product development, David Michael & Co., gives a final point worth remembering: If any sugar or fructose is permitted to meet the nutritional requirements, even at low percentages, they tend to improve the flavor impact, particularly upfront."

Cindy Hazen, an industry veteran with more than 25 years experience, developed food science chops in seasonings, dry blends, beverages and more. Today, when not writing or consulting she expands her knowledge of food safety as a food-safety officer for a Memphis-based produce distributor. She can be reached at cindy-hazen.com.

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