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The pasteurization conditions employed by makers of cloudy apple juice seem to be just right.
Manufacturers of cloudy apple juice should celebrate a little, because researchers just concluded that conventional pasteurization of this juice doesn’t degrade the apple juice’s phenolic compounds-at least not significantly.
Using the juice of Jonagored apples, Belgian researchers measured the effect of pasteurization at many temperatures on phenolic compounds in apple juice. They isolated a total of 42 phenolic compounds that they deemed to be heat-sensitive, and, of these 42, procyanidins were considered the most heat-sensitive.
The industry standard for cloudy apple juice pasteurization, known as “high temperature–short time” pasteurization (HTST), typically involves temperatures of 77–88°C and time lengths of 25–30 seconds. It’s just enough to keep microorganisms and enzymes from being active in the juice. When the researchers performed their phenolic tests on juice under these particular conditions, phenolic degradation was low-even for the most heat-sensitive of compounds. It’s comforting to know that pasteurization can maintain apple juice quality without compromising on this type of apple juice nutrition.
Some of the other heat-sensitive phenolic compounds found in apple juice were phenolic acids, quercetin glycosides, condensed tannins, flavonoids, and flavanols.
Nutritional Outlook magazine
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