Microbial decontamination of African nutmeg ( <i>Monodora myristica</i> ) powder using high-energy electron beam and gamma rays

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 (<i>p</i> < 0.05) the microbial loads of the African nutmeg powder with increasing irradiation dose. Microorganisms isolated and identified were <i>Cytobacillus kochii</i>, <i>Cronobacter spp</i>, <i>Pseudomonas stutzeri</i>, <i>Acinetobacter pittii</i>, and <i>Aspergillus flavus</i>. 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.