Extraction Process Optimization of Moringa Seed Extract and Its Inhibition on Bacillus cereus in Milk

To explore the antibacterial activity and stability of Moringa seed extract to against Bacillus cereus in milk. Single-factor and response surface were used to optimize the extraction process conditions of the antibacterial components of Moringa seeds with reference to the diameter of inhibition zone, to measure the stability of inhibition by temperature, pH and ultraviolet irradiation, and to explore the application of Moringa seed extract in liquid milk storage. The results showed that the optimal extraction condition of the antibacterial components of Moringa seeds was pH 3.1, the ratio for material and liquid was 1:70(g/mL), and leaching for 2.5 h at 50 ℃, the size of the inhibition zone was (27.23±0.58) mm; the MIC(Minimum Inhibitory Concentration) was 1.25 mg/mL and the MBC (Minimum Bactericidal Concentration) was 5 mg/mL. The effect of different pH and ultraviolet irradiation time on the antibacterial activity of Moringa seed extract was not significant (P>0.05), and the antibacterial activity of the blank group could be retained at 50.97% after heating at 100 ℃ for 30 min. The addition of MIC Moringa seed extract to pasteurized whole milk and skim milk had no significant effect (P>0.05) on milk odor, color and viscosity, and it effectively inhibited the growth of Bacillus cereus at 4 °C, extending its shelf life from at least 7 d to 14 d compared to pasteurized milk.Therefore, Moringa seed extract has efficient and stable inhibitory effect on Bacillus cereus in milk, and has the potential application in the dairy industry.