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ABSTRACT The quality of 7 commercial apple juices, after 11 ‐mo storage, was assessed on the basis of polyphenol and vitamin C contents, and also on the Trolox® equivalent antioxidant capacity (TEAC) value. Phenolic acids, flavonoids, and vitamin C were quantified using high‐performance liquid chromatography. It was shown that the content of phenolic acids in juices varied up to 2‐fold and flavonoids up to 4.5‐fold. Moreover, storage of juices resulted in a decrease of phenolic acids (5% to 21%), flavonoids (8% to 19%), and also of TEAC values (6% to 14%). Significant correlations between polyphenol content and TEAC values for fresh, stored, and all juices (fresh plus stored) and no correlation for vitamin C indicate that the TEAC value of apple juices depends mainly on their polyphenol content. Based on these results, it is concluded that the TEAC value, directly reflecting polyphenol content, may serve as a useful parameter to assess the quality of apple juice at any stage of its shelf life.
Gliszczyńska‐Świgło et al. (Sun,) studied this question.