Effects of ultrasound and chemical treatments on white mushroom (Agaricus bisporus) prior to modified atmosphere packaging in extending shelf-life.

Effects of pre-treatments of white mushrooms prior to modified atmosphere packaging on their physico-chemical and microbiological properties were studied during 12 days of storage at 4 °C. Physico-chemical and microbiological properties of differently treated mushrooms stored at 4 °C were significantly different (P < 0.05) from untreated ones. Washed samples exhibited the smallest respiration rate compared to all other samples. Hydrogen peroxide washing was effective in retaining mushrooms colour change. Furthermore, the diminishments in weight of ultrasound treated samples during storage were significantly (P < 0.05) low in comparison with the other four treatments. The weight loss for ultrasound treated samples were 3.52 %, 4.07 % and 4.59 % for Uca, UH2O2 and UH2O respectively. The lowest PPO activity was observed in Uca, UH2O2 followed by Wca, WH2O2, UH2O and WH2O treatments respectfully. Combined treatments showed lower polyphenol oxidase activity, retained antioxidants, delayed pseudomonas growth and did not cause any decline in tissue firmness during storage time implying that it could extend shelf life of white mushrooms up to 12 days at 4 °C.