Microbial decontamination of African nutmeg (Monodora myristica) powder using high-energy electron beam and gamma rays.

Abstract

This study investigated the microbial quality of African nutmeg powder irradiated with a high energy electron beam and Gamma rays. African nutmeg samples were purchased from a local market in Accra, Ghana, cleaned, milled, packaged, and irradiated separately using a high energy electron beam (with energy electrons of 9 MeV) and a ⁶⁰Co gamma source (dose rate of 2 kGy/h) at doses of 2, 4, 6 and 8 kGy. Un-irradiated African nutmeg powder served as a control. The microbial quality of the treated samples was determined using the ISO, 4832:2006 colony count technique. The presumptive microorganisms were identified using Matrix Assisted Laser Desorption Ionisation-Time of Flight Mass Spectrometry (MALDI-TOF MS). High energy electron beam and gamma rays significantly reduced (p < 0.05) the microbial loads of the African nutmeg powder with increasing irradiation dose. Microorganisms isolated and identified were Cytobacillus kochii, Cronobacter spp, Pseudomonas stutzeri, Acinetobacter pittii, and Aspergillus flavus. The results from this study suggest that gamma and high energy electron beam irradiators are equally effective and hence a high energy electron beam can be a good alternative to gamma irradiation for decontaminating African nutmeg powder with an effective dose of 6 kGy at which microorganisms were not detected.