Isoflavone Stability in Chocolate Beverages

摘要

This study determined the effect of UHT processing and three storage temperatures (4, 23 and 38℃) on the compositional stability of isoflavone levels in a chocolate flavored high protein beverage product containing isolated soy protein. Multivariate analysis indicated significant changes in isoflavone profile from pre- to post- processing. Univariate analysis of variance showed that shifts occurred within the isoflavone families, but family totals and total isoflavone retention were unaffected. Malonyl conjugates of all three isoflavone families, genistein, daidzein and glycitein decreased significantly, while a significant increase in all unesterified glucosides as well as the acetyl conjugates of daidzin and genistin was observed. Changes within the isoflavone families continued to occur in the ultra high temperature (UHT) processed product during storage. The degree of change was affected mostly by storage temperature, with higher temperatures directly affecting the greatest change. Total isoflavones and totals within an isoflavone family were not reduced over time or by temperature.