Integrated physical and chemical approaches for quality retention including browning suppression and value addition in white button mushroom (Agaricus bisporus)

The white button mushroom ( Agaricus bisporus ) is usually consumed for its nutrition value and health benefits but undergoes rapid quality deterioration including discoloration/ browning. Therefore, various physical including gamma radiation and Generally Recognized as Safe (GRAS) chemical treatment(s) have been explored to determine the best combination for its extended preservation. Combination treatments including cold water washing, sonication and irradiation (CSI) at optimized conditions was found to be the most effective in suppressing discoloration (expressed as browning index, BI) of mushroom for 22 days. Principal component analysis (PCA) on browning factors (BI, browning associated enzymes and total soluble phenolics) clearly showed that the overall change in CSI treated samples was negligible during storage. CSI treatment inhibited the activity of a PPO model system from mushroom source due to perturbation of its secondary structure as assessed by circular dichroism (CD) spectroscopy. Microbiological, physico-chemical, nutritional, health-protective (antioxidant and antimutagenic) and organoleptic qualities of CSI treated-stored mushroom were well retained while in untreated control most of these qualities were adversely affected during storage. Scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR) and electrochemical cyclic voltametric (CV) analysis further validated the better texture, intactness and redox behavior of CSI treated samples compared to the untreated ones. Besides, some aroma compounds were found to be enhanced which indicated value addition impact of processing. In the current study, a process for extended (> 20 days) preservation of mushrooms has been reported which may reduce the post-harvest losses, improve its trade and market access, and benefit the consumers.