Effect of gamma irradiation and evaporation on physicochemical, antibacterial, and antioxidant activity of selected high-quality herbal honey

This study was conducted to evaluate the influence of evaporation and gamma irradiation on physicochemical characteristics, antibacterial properties, and antioxidant activity of selected high-quality herbal honey (SH3), an Indonesian traditional herbal medicine recipe. Treatments consisted of untreated sample, evaporated SH3, irradiated SH3, and evaporated-irradiated SH3. Gamma irradiation dose of 10 kGy was applied in this study. Evaporation-irradiation treatments significantly decreased water activity (p < 0.01), moisture content (p < 0.01), and pH value (p < 0.001). Evaporated-irradiated samples also had the lowest total bacteria count (p < 0.05). Moreover, according to the prediction of Accelerated Shelf Life Testing (ASLT), shelf life increased from 180 d in untreated samples to 371, 335, and 419 d in the samples treated with evaporation, irradiation, or both, respectively. Antioxidant activity in irradiated and evaporated-irradiated samples was higher (p < 0.05) than untreated samples. Evaporation treatment increased antibacterial properties of SH3 (p < 0.05). The antibacterial characteristics of SH3 for Bacillus subtilis were observed to be similar among treatments. Except for evaporation treatment, similar findings were demonstrated for Escherichia coli antibacterial activity. The results of the present study suggest that the use of evaporation, combined with irradiation, may increase physicochemical characteristics, shelf life and antioxidant activity of SH3.