Effect of Adding Propolis on Quality Standards of Raw Milk and Yoghurt

Food additives spread around the world may have potentially harmful effects; Propolis is considered a natural additive that meets the increasing demand for natural antioxidants and antimicrobials in place of synthetic preservatives. Different concentrations of water extract of Propolis (WEP) were assessed; the pH and microbiological quality of raw milk were evaluated, as well as the quality characteristics and bioactives in manufactured yoghurt. WEP 20% was the best concentration compared to WEP 5% and 10% and exhibited an acceptable pH value of milk for 48 hours. The addition of increased concentrations of WEP 20% (1, 2, and 3%) resulted in a significant decrease and gradual reduction of the total bacterial, coliform, yeast, and mold counts compared to the control group. Propolis-supplemented yoghurt had higher pH values than the control group. Yoghurt groups treated with 1% and 2% WEP achieved the highest scores and significantly different (P<0.05) with control and 3% WEP groups in sensory examination until the end of the storage period. Furthermore, the counts of yeast and mold progressively decreased with the addition of higher concentrations of WEP throughout the storage period as 2%, 3% WEP groups were significantly different (P<0.05) with control and 1% WEP groups. The total phenolic, flavonoid content and antioxidant activity of yoghurt treated with WEP were improved and significantly different (P<0.05) compared to the untreated group. In conclusion, the raw milk and yoghurt preserved with propolis improved the quality of milk and increased bioactivity and nutritional benefits of yoghurt by elevating its antioxidant capacity. As a consequence, the produced yoghurt in our study proved that it is an acceptable product with functional, probiotic potential and has health-promoting properties that might be commercialized.