The Effects of Aqueous Extracts of Propolis Obtained from Different Extraction Methods as a Natural Preservative on Raw Milk

The effect of aqueous extracts of propolis gained using different extraction methods (soaking, Soxhlet, microwave and ultrasound) on the raw milk quality was investigated. Chemical (pH and acidity), microbial (total count, coliform, yeast and mold) and sensory (color and odor) properties were evaluated at 30 and 5 for 12 and 96 h, respectively. The highest amount of total phenolic compounds (7.4±0.1 (g/100g) and the antioxidant activity (52.0±1.8%) was observed in the Soxhlet extract. Despite the lowest amount of total phenolic compounds and antioxidant activity (2.6±0.6 g /100 g and 26±2.2%, respectively), soaking showed a more appropriate effect regarding growth inhibition of total bacterial counts (6.0±0.0 and 6.9±0.0 log cfu/ml), yeasts (4.5±0.0 and 4.0±0.0 log cfu/ml) and coliforms (5.1±0.1 and 4.1±0.0 log cfu/ml) at both temperatures of 5 and 30 compared to the control group showing the better performance of this methods in the extraction of the effective inhibiting compounds. The propolis extracts obtained from different extraction methods were effective in controlling pH and acidity in both temperatures during storage compared to the control samples. No organoleptic changes were observed during storage of the samples. Propolis extract (except extract gained by Soxhlet) extended the shelf life of milk at 30 and 5 for 3 and 24 h, respectively.