Quality improvement of Pleurotus mushrooms by modified atmosphere packaging and moisture absorbers

Abstract

Quality of Pleurotus ostreatus mushrooms was compared during cold storage under various temperatures and modified atmospheres with and without moisture absorbers. CO2 production followed a non-climacteric pattern and was about 0.50, 0.99 and 1.23 μmol CO2 kg−1 s−1 at 0, 4 and 7 °C, respectively, after 12 h. At the end of 11 days of storage, the respiration rates were very similar for all the assayed temperatures (±0.37 μmol CO2 kg−1 s−1). The best mushroom appearance was found at 0 °C, although for optimizing modified atmosphere packaging (MAP), 4 °C was selected to minimize low-temperature damage. When prolonging the storage beyond 7 days, quality characteristics dropped sharply and the mushrooms were not marketable, except when kept at 0 °C. Therefore, 7 days was the maximum recommended storage period for Pleurotus mushrooms. MAP at 4 °C for 7 days was created using microperforated polypropylenes (MPP1 and MPP2), low-density polyethylene (LDPE) and polyvinyl chloride (PVC) films. Results were compared with macroperforated polypropylene (PP) control packages. In order to avoid condensation, sorbitol and silica gel were used to modify the in-package relative humidity. Moisture absorbers did not modify the gas composition of the packages. Sorbitol promoted tissue leakage and cannot be recommended. Lower relative humidity was observed in packages containing silica gel and this did not affect the quality of the mushrooms. However, increasing amounts of silica gel increased weight loss in Pleurotus mushrooms, and high weight loss detected in PP packages made these unacceptable. MAP (15 kPa O2+5 kPa CO2) was found beneficial for maintaining acceptable quality of Pleurotus for 7 days at 4 °C.