Effect of malic acid on bioactive components and antioxidant properties of sliced button mushroom (Agaricus bisporus) during storage

Background: White button mushroom (Agaricus bisporus) is one of the most sensitive agricultural crops after harvesting and its antioxidant properties tend to decrease during post-harvest storage with the passage of time. OBJECTIVES: The possible role of exogenous application of malic acid as dipping treatment on bioactive components and antioxidant properties of sliced white button mushroom during storage was investigated. METHODS: The mushrooms were soaked in chilled malic acid solution at desired concentrations (1%, 3% and 5%) for 10 minutes or were dipped in chilled distilled water as control and were refrigerated (4°C) for 15 days. On each designated day (every 5 days) mushroom samples were taken out for further analysis. Total phenolic, chelating ability, and DPPH assay, as well as assay of reducing power, were evaluated as markers of bioactive components and antioxidant properties of sliced button mushroom. RESULTS: Malic acid treatment effectively maintained higher levels of bioactive components and antioxidant properties (as depicted by higher retention of phenolic and lower EC50 values for DPPH and reducing power) as compared to control during the whole storage period. On the other hand, chelating ability of mushrooms was not influenced by the malic acid treatment and a weak correlation was found between malic acid treatment and chelating ability retention. CONCLUSIONS: Our results suggest that dipping in 3% malic acid solution prior to storage can serve the purpose of maintenance of bioactive components and antioxidant properties of sliced button mushroom during storage.