Effects of Gamma Irradiation on Microbial and Sensory Properties of Fresh Dill and Savory

Vegetables play an important role in promoving health and preventing from diseases and they are good carriers to transmit bacteria, parasites, viruses and pathogens to humans. The use of vegetables disinfectants such as chlorine, with their own special risks, is a ways of preventing diseases. Shelf life of these products is limited, after three days at refrigerator, they will lose their consumption and will change to bulk of waste. Irradiation can be a practical treatment to increase safety and shelf-life and exporting of fresh vegetables. In this study, the effects of gamma irradiation doses of 0, 0.25, 0.5, 0.75 and 1 kGy on microbial and sensory qualities of fresh dill and savory at ambient temperature and 4 °C were investigated. According to the statistical results (p < 0.05), there was a significant difference the mean of two treatments of main effects of dose, temperature and time, and interaction of dose*time and time*temperature. The interaction of dose*temperature on mold and yeast count was not significant. The effect of time*temperature*dose was not significant on microbial tests. In sensory-taste tests, there was a statistically significant difference between the mean of two main effects of storage time on the parameters of softness, shape, taste, aroma and color. There was no statistically significant difference between other treatments for measured parameters. According to results samples which were stored at ambient temperature due to high microbial load in first two days were removed of study. In irradiated samples, until the eighth day, a dose-dependent reduction of microbial load was observed. Foodborne pathogenic bacteria including E.coli and Staphylococcus aureus were present in control and 0.25 kGy irradiated samples. Considering acceptable results of microbial and sensory assays, gamma irradiation at dose of 0.5 kGy at 4 °C, can enhance shelf life to 8 days and decrease fresh dill and savory wastes.