Effect of Prolonged Cold Storage on the Dynamics of the Enzymatic and Non-Enzymatic Antioxidant System in the Mesocarp of Avocado (Persea americana) cv. Hass: Relationship with Oxidative Processes

Abstract

This work evaluated the enzymatic and non-enzymatic antioxidant defense systems of avocados cv. Hass stored at 7 ± 0.5 °C for 10, 20, and 30 d, and at the stage of edible ripeness. The enzymatic antioxidant enzyme system included superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), and the non-enzymatic antioxidant system was composed of total phenolic compounds (TPC), total carotenoids (TC), α-, β-, and γ-tocopherols, as well as hydrophilic (H-AOX) and lipophilic (L-AOX) antioxidant activities. In addition, polyphenol oxidase (PPO) and lipoxygenase (LOX) activities, TBARS values and pulp browning area were determined. At edible ripeness, low SOD and POD but higher CAT activities were evidenced in response to their joint participation in the oxidative stress developed. In addition, low content of γ-tocopherol and higher contents of TPC and TC were evidenced and suggest their individual or joint participation in defense against oxidation. The other compounds and activities evaluated tended to remain constant. Oxidative damage was evidenced by the increase in PPO activity and TBARS values, while LOX did not play a significant role. Pulp browning area did not surpass 6% in affected fruit. The results indicate that under these conditions oxidative stress was largely restrained by the endogenous fruit antioxidant defense system.