Modification to any sweetener system involves understanding four key functional elements: flavor (sweetness and other influences); freezing point depression (influence on the dynamics of frozen water); bulking (contribution to total solids); and control of water mobility. Achieving desirable objectives (cost reduction, heat shock stability, etc.) with minimal effects on eating characteristics and consumer appeal is complicated as sweeteners vary substantially with regard to all these elements. The cost per unit sweetness needs to be considered.
It is best to quantify these elements for each alternative sweetener system being considered.
Sweetness is relatively easy. This involves the concept of sucrose equivalence (SE) (i.e., theoretical sweetness), in which sweeteners are assigned sweetnesses relative to sucrose. If sucrose is arbitrarily given a SE value of 1.0., 36 DE corn syrup solids, considered to be 45% as sweet as sucrose, has an SE of 0.45. Each individual sweetener should have an associated SE. The total sweetness of a mix is the sum of sweetness contributions of individual sweeteners, each of which is calculated by multiplying SE by use rate. The relatively low SE of lactose makes the matter of whether to include it in sweetness calculations optional. When the calculated sweetness falls within ± 0.5% of target (15% is a classical target for ice cream), the difference will not likely be noticed. Outside this range, it is wise to re-evaluate the effect of the change.
Assessment of non-sweetness flavor factors cannot be done quantitatively, but must be based on the effect of any individual sweetener(s) on flavor profile (e.g., aftertaste, compatibility with added flavors, etc.), and, ultimately, in-product sensory evaluation.
Albeit a complex calculation, freezing point depression and its effect on freezing profile can be calculated with precision. The importance of freezing profiling cannot be understated. Freezing profile helps understand the dynamics between ice and water at any given temperature. Comparing mixes and water behavior throughout the freezing process is useful in understanding freezing functionality, sensory appeal and distribution tolerance.
The bulking effect of sweeteners is simple to evaluate by comparing total solids levels of the current composition and alternatives. If the difference in total solids between two mixes is within ± 0.5% of each other (all other elements being equal), it is unlikely any sensory property will be negatively influenced. However, too high or too low in solids can result in sticky/gummy or coarse/icy ice cream, respectively.
Ability to influence water behavior during freezing of ice cream can be attributed to large molecular weight components of carbohydrate sweeteners. Degree of polymerization, or DP, represents the number of monosaccharide units in any given carbohydrate. Useful water control is associated with carbohydrates composed of at least four monosaccharide units, i.e., DP 4 and greater. To date, this functionality has not been quantified. We believe this can be done using a new concept that assigns to each sweetener and/or bulking agent a water control index (WCI) that reflects the level of components in the ingredient sized DP 4 or greater. This also reflects the relative ability of any sweetener and/or system to manage water. Sucrose (DP2) and high fructose corn syrups (DP1) have WCI’s of zero; 36 DE corn syrup solids has a WCI of 0.64 representing the percent of sweetener solids of size DP4 or greater. The total mix WCI is determined by multiplying WCI times the percent ingredient use rate then summing the totals similar to determining mix theoretical sweetness. WCI values should be kept within ± 15% of each other to maintain equivalent water mobility control.
It is also important to consider changes to non-sweetener components that may be helpful. If equivalency of freezing point depression involves slightly lower total solids, parity could be restored by increasing milk solids not fat. Similarly, compensation for reduced WCI could be made by adjusting the stabilizer level.
Economics always plays a critical role. The cost-per-unit sweetness of individual sweeteners has become extremely helpful in developing novel approaches for modifications to any sweetener system. n
For more on understanding ice cream, and additional Tharp & Young commentary on sweeteners and novel approaches go to www.onicecream.com.
Join Bruce Tharp & Steve Young at Tharp & Young On Ice Cream, Technical Short Course. Workshops, and Clinics, December 3-5 , Las Vegas. For more, go to www.onicecream.com or call 610/975-4424 or 281/596-9603.
