Influence of Ripening Process on Pecan Nut (Carya illinoinensis) Kernel Quality: Phenolic Profile, Antioxidant Activity, and Carbohydrate Composition

Pecan nuts (Carya illinoinensis) provide a wide range of bioactive compounds (particularly polyphenols) that improve the nutritional quality of diets. This study aimed to monitor the evolution of polyphenolic compounds (total phenols, total flavonoids, total flavanols, total condensed tannins, and total o-diphenols), the phenolic profile, the antioxidant activity, and the sugar concentration during pecan nut development in three Tunisian cultivars. Condensed tannins (41.98-221.13 mg catechin assay equivalents g(-1) FW) were the dominant class of phenolics at all maturity stages, followed by total phenols (12.25-57.92 mg gallic acid equivalents g(-1) FW). Ellagic acid and catechin were the most abundant phenolics at all maturity stages. The highest phenolic content and antioxidant activity were found at an early stage of ripening but as maturity progressed, a decreasing trend was observed. Sucrose (6.09-30.79 mg g(-1) FW) was the predominant sugar followed by fructose and then glucose. A decreasing and later increasing trend of total carbohydrate concentration was detected during nut development. A Canonical Discriminant Analysis of the data succeeded in separating the three pecan cultivars due to their unique characteristics. Overall, the cultivar and the degree of maturity are the major factors controlling the chemical composition and antioxidant capacity of pecan nuts. This study provides more information on the optimal period when the maximum concentration of these health-enhancing compounds is found for use in food, nutraceutical, cosmetic, and pharmaceutical applications.