Efecto del tamaño del corte en pieles de naranja y pomelo como estrés abiótico para inducir la biosíntesis de compuestos fenólicos

Abstract

Wounding is one of the main postharvest stresses that horticultural products experiment, mainly during their handling and minimal processing. This mechanical damage represents abiotic stress that stimulates secondary metabolism and induces the synthesis of bioactive compounds. This research aims to evaluate the biosynthesis of phenolic compounds in citrus by-products as a result of different wounding shapes. For that purpose, orange and grapefruit skins, obtained from citrus industry, were wounded into rectangular shape, 8,5×2 cm (CTRL); 1×1 cm dices (D), and 0,25 cm grated (R). They were kept at 15 ºC and at 65 % of relative humidity. Their total phenolic compounds (CFT) and total antioxidant capacity (CAT) were analyzed after 0, 8, 24 and 28 h. The results showed that CFT and CAT values decreased after 24 h, so it is recommended to sample byproducts between the first 8 hours after wounding to obtain a natural extract enriched in bioactive compounds. Grated (R), the most severe abiotic stress, is not an adequate technique to induce the synthesis of secondary metabolites and revalue these citrus skins, because it let full recovery of flavedo, but partial of albedo. On the contrary, rectangular and dice shapes (CTRL and D) completely recover flavedo and albedo. This is experimentally justified by the fact that CFT and CAT obtained from grated skin were ~50 and ~46 % lower. Differences between CTRL and D were just observed in CAT values. Total antioxidant capacity of CTRL was ~30 % higher. These results show that wounding shape of orange and grapefruit skin induces different accumulation of phytochemical compounds.