Gamma irradiation effect on the microbial load and physicochemical properties of honey from Ghana

Abstract

Abstract. Larbi DA, Klutse CK, Adotey DK. 2022. Gamma irradiation effect on the microbial load and physicochemical properties of honey from Ghana. Cell Biol Dev 6: 94-107. The honey's high sugar concentration and low pH give it antimicrobial properties and make it difficult for microorganisms to grow. This study is to ascertain microorganisms' presence in Ghanaian honey, the sources of microbial contamination, the physico-chemical properties of honey, and the effect of gamma radiation on the microbial load. Furthermore, 90 honey samples were collected from Brong Ahafo, Ashanti, and Greater Accra, Ghana, with 30 from each region. Honey was sampled directly from the beehive with the comb before the farmer harvested, and honey was sampled from retailers who buy directly from the farmer. The effect of gamma radiation on the microbial load was studied using a 60Co source gamma irradiation facility at doses of 20 kGy, 30 kGy, and 40 kGy on the presence of microbes and the physicochemical properties (pH, reducing sugar, apparent sucrose, and ash content) of honey. The pH values obtained for the Honey Comb samples were in the range of 3.6-3.9, and the pH for the Retail samples was in the range of 4.9-5.6. Microorganisms were not detected in about 70% of the honey sampled directly from the honeycomb. The mean microbial count in the remaining 30% was within the range of 30-35%, whereas all the honey sampled from the retailers was contaminated with microbes. The mean microbial counts in the retailer samples were 148 CFU/g, 183 CFU/g, and 271 CFU/g for Ashanti, Brong Ahafo, and Greater Accra Regions, respectively. These values were significantly higher than the required maximum relative to the MERCOSUR (Mercado Comun del SUR) standard (? 100 CFU/g). The low level of microbial detection in the Honey Comb samples (30-35 CFU/g) could be due to their relatively low pH levels (3.6-3.9) compared to the retailer samples with pH within 4.9-5.6. The ash content of all the honey sampled and analyzed was within the required standard, with an average of 0.16% in the honeycomb samples and an average of 0.62% for the retail samples. The apparent sucrose concentration (in percentage) in honey sampled from the retailers was within the range of 22-33%, which is beyond the required maximum as stipulated by the CODEX Alimentarius Commission (? 10%). The study showed that a 20 kGy gamma radiation dose was enough to denature the microbes and preserve the honey's essential qualities. Finally, to ensure good quality honey on the Ghanaian market, it is recommended that honey meant for human consumption should undergo gamma irradiation (cold pasteurization).