Dinamics of phenols and antioxidant capacity changes in pulp, peel, and seed of avocado (Persea americana Mill. Var. Hass) during preharvest maturity

Background and objectives: World consumption of avocados (Persea americana Mill. Var. Hass) and its industrialized derivatives has increased rapidly, and the volume of wastes production. In the avocado fruit, the edible and inedible fraction contains diverse bioactive compounds, whose content depends on the maturation degree attained at harvest. The study's objective was to evaluate the content of phenolic compounds and antioxidant capacity of the pulp, peel, and seeds of avocado (Persea americana Var. Hass) according to the degree of pre-harvest maturation. Methods: An experiment was established with 18 avocado trees (Persea americana Var. Hass) in a commercial orchard in Jalisco, Mexico. 345 fruits were marked to record monthly growth. From the beginning of maturation on the day after fruit set (DAFS) 283, fruits were collected on five dates to study the changes in the chemical and functional composition of the pulp, peel, and seed until DAFS 402 (n=4). Results: The decrease in moisture content and the increase in dry matter in all collections were significant only in the seed, while the fat content in the pulp increased continuously up to 28% (p< 0.05). The content of total phenols (CTP) measured in pulp, seed, and peel (1.13±1.08, 32.43±12.18, and 101.39±33.49 mgEAG/Kg, respectively) remained stable throughout the pre-harvest maturation (p< 0.05). The tendency of the antioxidant capacity measured in the same structures by DPPH (10.73±2.11, 221.37±58.53, and 443.98±109.52, µmolET/Kg respectively) and ABTS (2.984±0.67, 33.137±6.34, 79.757±23.78, µmolET/Kg respectively) corresponded to the CTP (p&0.05); however, in the peel, a significant increase occurred from the DAFS 360. In analyzing the samples by HPLC of 13 compounds studied, traces of gallic, dihydroxybenzoic, syringic, and p-coumaric acids were found. Catechin, caffeic acid, and chlorogenic acid were in the seed (3.14±5.49, 0.903±1.31 and 0.304±0.19 ppp, respectively) and peel (14.17±10.32, 59.83±22.13 and 0.39±0.13 ppp, respectively) in quantifiable amounts. In the latter, chlorogenic acid and catechin steadily increased as maturation advanced (p< 0.05). Conclusions: During pre-harvest maturation, the edible faction of the avocado does not show essential changes apart from the increase in fat content; however, the peel presents the highest content of total phenols with an increase in the content of chlorogenic and caffeic acid.