Postharvest browning alleviation of Agaricus bisporus using salicylic acid treatment

Abstract

The cap browning of white button mushroom (Agaricus bisporus) has been attributed to postharvest senescence which by increasing reactive oxygen species (ROS) accumulation leads to membrane lipids peroxidation, disrupt cellular compartmentalization, resulting to contacting of polyphenol oxidase (PPO) with phenols and occurring cap browning. In this study, the effects of 0, 50, 250, 500 and 1000μM salicylic acid (SA) treatment applied by postharvest dipping (60s at 20°C) on cap browning of mushroom storage at 4°C for 21 days was investigated. Browning of mushroom cap was accompanied by an increase in electrolyte leakage and thiobarbituric acid-reactive substances (TBARS) content associated with H2O2 accumulation. SA treatment at 250μM delayed cap browning and retarded increases in electrolyte leakage, TBARS and H2O2 accumulation. The SA treated mushroom exhibited significantly higher phenylalanine ammonia lyase (PAL) enzyme activity, associated with lower PPO activity. Higher PAL enzyme activity in mushroom treated with SA coincided with higher total phenol accumulation and higher DPPH scavenging activity during storage at 4°C for 21 days. Also, mushroom treated with SA showed lower H2O2 accumulation, which results from higher antioxidant enzymes superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX) activity. These results suggest that SA treatment at 250μM can be used as a useful technology for the alleviation of postharvest browning of mushroom cap by maintaining membrane integrity due to enhancing antioxidant system activity and also, phenols accumulation.