Effect of Storage on the Content of Polyphenols of Minimally Processed Skin-On Apple Wedges from Ten Cultivars and Two Growing Seasons

In this study, the polyphenolic composition of skin-on apple wedges from ten cultivars was examined during chill storage and over two growing seasons. Individual polyphenol compounds were measured using HPLC resulting in the total polyphenolic index (TPI). Total phenolic content (TPC) was quantified using the Folin−Ciocalteu assay. Chilled storage had a significant effect (P < 0.001) on the polyphenol composition of all ten cultivars grown in 2007 and 2008. Total phenolic indices (sum of individual polyphenols) and TPCs of nine of the ten cultivars significantly decreased (P < 0.001) after 5 days of storage at 2−4 °C. These indices increased in case of Shampion apples over the same storage period. Changes in the most abundant compounds (−)-epicatechin, procyanidins and chlorogenic acid were largely responsible for changes in overall TPI. Percentage loss was higher for compounds such as phloridzin with a degradation of up to 100%. Irrespective of the different starting level of specific polyphenols in each year; storage resulted in a similar percentage loss/gain for each cultivar.