Inhibitory Effect of Ascorbic Acid in Enzymatic Browning and Preservation of Quality in Fresh Pistachios (Pistacia Vera L.)

The enzymatic browning that occurs in the hull of fresh pistachio fruit significantly reduces its postharvest shelf life and marketability. This study is focused on assessing the potential of ascorbic acid (AA), known for its anti-browning properties, in managing the enzymatic browning of freshly harvested pistachio cv. 'Akbari'. Freshly harvested pistachio fruits were treated with different concentrations of AA (0, 3, and 6%) for 3 min. The treated fruit samples were carefully packed into plastic trays and enveloped with low-density polyethylene (LDPE) packaging material. These packaged samples were then stored under controlled conditions at a temperature of 5 ± 1 °C, with a relative humidity of 90 ± 2%, for a total duration of 60 days. Various parameters, including weight loss, electrolyte leakage, color attributes, total phenolic compounds, polyphenol oxidase (PPO) activity, microbial populations, peroxide value (PV), and free fatty acid (FFA) content, were systematically evaluated at 20-day intervals over an 60-day storage period. The results indicate that the concentration of 6% AA were most effective on reduced weight loss, electrolyte leakage, and color changes in the pistachio hull. Additionally, AA effectively preserved the total phenolic content and inhibited PPO activity, contributing to the reduction of enzymatic browning. Moreover, AA exhibited antimicrobial properties, leading to a decrease in microbial populations and decay incidence. Furthermore, AA treatment resulted in lower PV and FFA content, indicating reduced lipid oxidation in pistachio fruits. Overall, utilizing AA offers an alternative approach to reduce hull browning while preserving the freshness and quality of harvested pistachios.