QUALITY ASSESSMENT OF GAMMA IRRADIATED POWDERED DRIED MUSHROOMS (PLEUROTUS PULMONARIUS AND VOLVARIELLA VOLVACEA) IN EXTENDING SHELF LIFE DURING STORAGE

Abstract

Mushrooms are soft textured and prone to deteriorate shortly after harvest if not properly stored. In view of their short shelf life under normal ambient conditions of temperature and humidity, it is imperative to preserve it by processing to extend shelf life for off season use. Drying is one of the common methods used for mushrooms for preservation owing to its easiness and economical nature. Irradiation is known to be a safe technology for treating food products using ionizing radiation. Gamma ray ionizing radiation is used to extend the shelf-life of food products and results in the inactivation of foodborne pathogens. This paper showed the ability of gamma irradiation for decontamination of powdered dried mushrooms (Pleurotus pulmonarius and Volvariella volvacea) and reliable process for edible mushrooms storage in commercial industries. The mushrooms were dried at temperature of 45-55ºC, powdered and given gamma irradiation at 0 (control), 2, 5 and 10 kGy. Results showed that irradiation at 2 kGy had the ability to reduce the microbial loads (bacterial and fungal colonies) in powdered dried mushrooms and there was no presence of microbes after irradiated at 5 and 10kGy. Nevertheless, after storage 9 months, the microbial loads increased in the control samples but maintained low in samples (Pleurotus pulmonarius and Volvariella volvacea) irradiated at 5kGy (1.4x102, 1.5x101 cfu/g) and 10kGy (4x101, 5x101 cfu/g). There were no significant changes in colour of all samples during storage. Although there were some changes observed for proximate compositions due to the gamma irradiation, the results obtained were no significant differences (P<0.05) and showed that the integrity of these compositions in the mushrooms were minimally affected as no adverse effects were observed. Irradiation at dose 5 and 10kGy are suitable in maintaining the quality of the powdered dried samples and also extended the storage period.