Evaluation of Extracted Honey Bee Propolis as a Natural Preservative of Raw Cow’s Milk in Awi Zone, North western Ethiopia

This study aimed to evaluate the effectiveness of honey bee propolis as a natural preservative for raw cow’s milk. Propolis was collected from three agro-ecologies in the Awi zone Banja, Dangla, and Chagni, and extracted using 70% ethanol. Raw milk samples were obtained from the Injibara University dairy farm and divided into five groups, with different concentrations (0ml, 5ml, 10ml, 15ml, and 20ml) of propolis added to 100ml of milk in sterilized bottles. The study analyzed the milk’s quality through clot-on-boiling, alcohol, and methylene blue reduction tests, and microbiological parameters, including aerobic plate count (ABC), coliform count (CC), and yeast and mold counts (YMC). Data analysis was performed using SAS version 9.4. Results indicated that both agro-ecology and propolis concentration significantly impacted raw milk quality (P < 0.001), with interaction effects on coagulation and microbial counts (P < 0.05). The control group showed the shortest coagulation time, while propolis-treated milk exhibited the longest. Furthermore, microbial quality was influenced by both the agro-ecology and propolis concentration, with the lowest microbial load found in milk treated with 5ml and 10ml of propolis from the Guangua Woreda (lowland). In conclusion, the study demonstrated that propolis, particularly at 5ml and 10ml concentrations from Guangua Woreda, effectively extended the shelf life of raw milk by reducing microbial load.