Title: Alternative Sweeteners

508 Mitchell et al.
conventional ice cream type products, sucrose is the primary freezing point depressant,
and alternative ingredients such as polydextrose are typically compared
with sucrose.
The effect that an ingredient has on freezing point depression is a function
of its molecular weight. Sucrose is a disaccharide. A larger molecule such as
polydextrose is somewhat less effective as a freezing point depressant. A smaller
molecular weight ingredient such as sorbitol would have a greater effect on freezing
point depression than either sucrose or polydextrose. Ideally, a balance can
be achieved with several ingredients to match the effect of sucrose.
The comparative effects of polydextrose, sucrose, and sorbitol on freezing
point have been reported (9, 10). The freezing point of a 5% solution of these
three ingredients was as follows: polydextrose, .147°C; sucrose, .298°C; and
sorbitol, .613°C.
D. Preservation/Osmotic Activity
Another function that sucrose serves, particularly at higher use levels, is that
of preservation. Sugar at high concentrations reduces water activity (aw). Under
conditions of reduced water activity, there is less water available for the growth
of microorganisms and there is also greater osmotic pressure. When the sucrose
level is reduced in a recipe, the new product may have shelf-life problems with
respect to bacteria, yeast, or mold growth that the original product did not have.
There are several ways this problem can be addressed. One approach is to replace
sucrose with ingredients that have a similar effect on water activity. Polydextrose
can be used to help maintain the soluble solids level while limiting the calories.
In this regard, polydextrose can be used to decrease the water activity of a product
as described previously. An equal weight of polydextrose will not have as great
an effect on aw as sucrose.
It may be beneficial to make formulation changes in reduced-calorie products
to maintain a comparable shelf-life. One technique is to decrease the pH to
inhibit microorganisms. Also, the use of chemical preservatives such as sodium
benzoate or potassium sorbate may be particularly useful in calorie-modified
products.
E. Cryoprotectant
Several applications have been suggested for the cryoprotectant capability of polydextrose.
Cryoprotection involves stabilizing foods against the damaging physical
effects of freezing. This is a function that is well recognized for many soluble
ingredients, particularly sugars. This function has been described in fish products,
including surimi (11, 12), and meat products (13).