Effect of 60Co gamma irradiation on postharvest quality and selected enzyme activities of Volvariella volvacea

Volvariella volvacea fruit bodies were exposed to six different dosage levels (0, 0.2, 0.4, 0.6, 0.8, and 1.0 kGy) of 60Co gamma ray source, and then stored at 16 °C and 55-60% relative humidity for 7 d. Storage of the 0.8-kGy treatment group resulted in the highest sensory evaluation score, (increase by 51.85% than other treatments). The activity of selected enzymes involved in postharvest deterioration were also studied. The results showed that irradiation treatments have achieved significantly better commercial appearance after 7 d of storage due to slower postharvest mushroom softening, browning, weight loss (10.53%-34.73%) and respiration rate (17.20%-48.72%) than control. respectively.Samples irradiated with the 0.8-kGy dose performed better than other treatments. The control showed a significantly higher malonaldehyde (MDA) level than the irradiated samples (5.5%-45.27%). Increased catalase (CAT) activity (P < 0.05) was also observed in the samples receiving doses of 0.8 and 1.0 kGy after storage for 4 and 5 d, respectively. Superoxide (SOD) dismutase activities in the irradiated samples (13.68-40.53%) were significantly higher than those of the control, while the microbial populations decreased in all irradiated samples compared with the control. These findings suggested that irradiating V. volvacea mushrooms with 0.8 kGy of 60Co gamma rays could maintain their quality.