AS WITH BAKERY PRODUCTS, sugar’s most critical role is to control the texture of frozen dairy and frozen novelty products, began Jon Hopkinson, Ph.D., a technology consultant specializing in frozen desserts, in his presentation titled “Tips for Reducing Sugar in Frozen Dairy and Novelty Products.” It does so by managing water.
Sugar plays a crucial function in both ice cream-type desserts that are frozen while stirred, and quiescently frozen desserts, which are usually frozen in molds. First, it controls the freezing and melting characteristics of these products. It also contributes sweetness, viscosity, color and secondary flavors, such as browning flavors developed during pasteurization.
“Sugars are the most important control variables to determine proper freezing properties of mixes during processing,” explained Hopkinson. “Freezing-point functionality must somehow be compensated for when sugars are taken out of the formula.” Shelf-life is affected by sugar’s effect on product melting point, sugar migration and freeze-thaw recrystallization properties. For example, sugars can migrate and recrystallize on the surface of ice-pops, creating little round “cancer spots” on the surface during freeze-thaw cycles.
Colligative properties like freezing point are determined by the number of molecules (particles) per fixed unit of weight. Small molecular weight ingredients, like monosaccharides, contribute more particles per gram than disaccharides, and therefore have a greater effect on freezing point depression. The molecular weight of sucrose is 342; for glucose and fructose it is 180; and for erythritol, it is 122. Thus, selecting sucrose substitutes based on their molecular weights can help control freeze-point depression.
So, what if the goal is to reduce the sugar content in a gelato, sorbet or ice cream product by 50%, asked Hopkinson? He presented some strategies, with the caveat that one should carefully check the patent literature before mapping out a product development strategy.
One can hypothetically replace some or all the sugar with sugar alcohols (e.g., sorbitol), but their negative eﬀects on digestive wellbeing at higher concentrations merit careful consideration. Erythritol, on the other hand, does not have the digestive liabilities of sugar alcohols, noted Hopkinson. “In fact, one can get away with 1:1 substitution of sugar with erythritol while keeping sweetness constant, cost permitting. However, you may also need to add additional bulking agents in order to control the amount of water available to freeze.”
A second strategy is to replace some of the sucrose with lower molecular weight ingredients. For example, one can use combinations of erythritol, glycerol and fructose, with a sweetness boost from high-potency sweeteners, such as acesulfame-K or natural stevia.
A third strategy for frozen dairy desserts is to remove lactose (a disaccharide) by ultra-filtration and add-back monosaccharides, such as glucose and fructose. This could be expensive, so another alternative might be to treat the milk with lactase enzyme, converting lactose to the monosaccharides, glucose and galactose. Hopkinson warned that there may be a patent issue here as well.
A fourth strategy would be to replace sugar with a fruit juice and bulking agent. However clean-sounding the juice component, this will likely require adding additional bulking agents with complex-sounding names (e.g., maltodextrin, erythritol). Under the pending nutrition labeling regulations, juice concentrates will need to be factored in as an Added Sugar on the nutrition label. “Trying to achieve an ‘all juice’ claim for a frozen dessert can be a regulatory nightmare, as most single-strength juices don’t contain enough sugar to meet processing, taste and product-quality requirements,” warned Hopkinson.
And, finally, “one can just remove a portion of the sugar from a formula and leave it at that,” concluded Hopkinson. “Quality won’t be as good, but at-least some consumers may be willing to accept the trade-off in the interest of reduced sugar and calories.” He finished his presentation by illustrating the very long and complex ingredient statements from some mainstream frozen desserts with low sucrose or no sucrose, showing that there is much room for improvement.
“Tips for Reducing Sugar in Frozen Dairy and Novelty Products,” Jon Hopkinson, Ph.D., technology consultant specializing in frozen desserts
This presentation was given at the 2018 Sweetener Systems Conference. To download free presentations and the Post-conference summary of this event, go to https://globalfoodforums.com/store/sweetener-systems-conferences/
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