Fate of apple peel phenolics during cool storage

Consumption of certain phenolics in the diet is considered beneficial to hu man health, In this study, individual phenolics were measured by diode-arra y HPLC at monthly intervals in the peel of Granny Smith, Lady Williams, and Crofton apple cultivars stored in air at 0 degreesC for 9 months. The conc entrations of total phenolics significantly differed among the cultivars ex amined, with Lady Williams peel having significantly more phenolics (over 4 000 mug(.)g(-1) peel fresh weight) than Crofton; (2668 mug(.)g(-1) peel fre sh weight) and Granny Smith, which had the lowest concentration of total ph enolics (1275 mug(.)g(-1) peel fresh weight). There were also significant d ifferences in individual phenolics among cultivars and during storage. Quer cetin glycosides were the only flavonols identified, with quercetin rhamnog lucoside being the most abundant phenolic in the peel. Chlorogenic acid was the major cinnamic acid derivative, with high concentrations, up to 412 mu g(.)g(-1) peel fresh weight, in Crofton peel. A pre-storage diphenylamine ( DPA) treatment had few significant effects on peel phenolic metabolism. Whe re differences did occur, fruit treated with DPA retained higher concentrat ions of total peel phenolics during storage than fruit not treated with DPA . Storage of all cultivars for up to 9 months in air at 0 degreesC induced few significant changes in the peel phenolic concentrations. This indicates that phenolic metabolism in apple peel is relatively stable, and the healt h benefits of phenolics in apple peel should be maintained during long-term -storage.