Effect of gamma-irradiation on Microbiological, Biochemical and Sensory Qualities of Commercial Powdered Cocoa Beverage Premix

Abstract

Low-dose gamma irradiation has been considered effective for improving the microbiological safety of fresh and processed foods. In the present study, gamma-rays in the dose-range of 0-15 kGy were used for microbial decontamination of commercially available, ready-to-use powdered cocoa beverage premix. Premix was artificially inoculated with Aspergillus oryzae, Saccharomyces cerevisiae and Bacillus cereus. A complete inactivation of the tested microbes was observed after treatment with 10-15 kGy in inoculated and with 2.5-5 kGy in non-inoculated commercial cocoa beverage premixes. Thiobarbituric acid (TBA) values increased linearly with the magnitude of radiation dose. The peroxide value, amino nitrogen content and protein solubility were not significantly affected by the gamma-irradiation. The overall sensory quality of irradiated premix was not significantly affected with the radiation doses less than 10 kGy. The results indicated that low-dose gamma-radiation (up to 10 kGy) can be used to improve the microbiological quality of powdered cocoa beverage premixes before being loaded into vending machines.