Antioxidant Activity and Phenol Content in Different Tissues of Stone Fruits at Thinning and at Commercial Maturity Stages

Fruits and their by-products are a font of polyphenols and antioxidant compounds which are heterogeneously distributed in the different tissues. These by-products include thinned fruits that contains large amounts of bioactive compounds. The present study aims to determine changes in antioxidant activity and polyphenols in different tissues (peel, flesh and seed) of five stone fruits (apricot, peach, flat peach, nectarine and plum) at thinning and at commercial maturity stage. The phenol and flavonoid contents decreased from thinning to harvest for peel and flesh (up to 95%). Hydroxycinnamic acids, mainly neochlorogenic and chlorogenic, were the predominant groups of phenols in both maturity stages, thinning and commercial. The seeds were the tissues with the highest antioxidant capacity, particularly the flat peach seed in both maturity stages. Thus, thinned stone fruit extracts might be used as a source of beneficial compounds. Also, seeds of some fruits at commercial maturity, a by-product of juice and jam industries, could be a promising source of bioactive antioxidants.