Studies Of The Effects Of Gamma Irradiation On The Microbial Load And Physicochemical Properties Of Ghanaian Honey From The Ashanti, Brong Ahafo And Greater Accra Regions

ABSTRACT Honey is a universal product with a wide usage throughout the life spectrum. It is a substitute for sugar for many people, an energy booster, helps maintain the blood sugar level and research has shown that it has the potential for cancer prevention. The high sugar concentration of honey and its low pH gives honey antimicrobial properties and makes it difficult for microorganisms to grow. However, research has provided evidence of the presence of microbes in honey. The microbes are introduced into honey through primary and secondary sources. The primary sources are due to honeybee foraging activities resulting in the transfer of pollen and other microbial species in the air, soil and plants into the product before it matures. The secondary sources of contamination are due to the harvesting process, materials used for harvesting and storage of the honey; as well as the method used in extracting and treating honey before it is sold to the consumer. Accordingly, it is imperative that the quality of honey on the Ghanaian market is monitored regularly to provide data on the microbial load. This study endeavours to ascertain the presence of microorganisms in Ghanaian honey, the sources of microbial contamination and the effect of gamma radiation on the microbial load as well as the physico-chemical properties of honey. Ninety (90) honey samples were collected from three regions; Brong Ahafo, Ashanti, and Greater Accra [Thirty (30) from each region]. Sampling was conducted using the farmer-to-retailer route, that is, honey was sampled directly from the beehive with the comb before the farmer harvested, samples were taken after the farmer had harvested and treated and finally 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 xiii 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 honey samples were analyzed for the presence of Total Viable Counts, Faecal sp., Clostridium sp., Staphylococcus sp., and Salmonella sp. The Plate Count Method of microbial analyses was used to determine the microbes. For the Total Viable Count, Plate Count Agar was the media used; Eosin Methylene Blue agar for Faecal sp., Perfringens Agar for Clostridium sp., Xylose Lysine Deoxycholate Agar for Salmonella sp., and Baird Parker Agar for Staphylococcus sp. The samples were also analyzed for Reducing Sugar and Apparent Sucrose using Titrimetry. pH was determined with a pH meter and Ash Content was determined by Gravimetry. The pH values obtained for the Honey Comb samples were in the range (3.6 – 3.9), and the pH for the Retail samples were in the range (4.9 – 5.6). Microorganisms were not detected in about 70% of the honey sampled directly from the honey comb and the mean microbial count in the remaining 30% were within the range 30% - 35% whereas all the honey sampled from the retailers were 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 were within the required standard with an average of 0.16% in the honey comb samples and average of 0.62% for the retail samples. The apparent sucrose concentration (in xiv percentage) in honey sampled from the retailers were within the range 22% - 33% which is beyond the required maximum as stipulated by the CODEX Alimentarius Commission (≤ 10%). From the study, it was realized that a 20 kGy gamma radiation dose was enough to denature the microbes as well as preserving the essential qualities of the honey. To ensure good quality honey on the Ghanaian market, it is recommended that honey meant for human consumption should undergo gamma irradiation (cold pasteurization).