Effect of bacteriocin and lactoperoxidase system in pasteurized milk production
Nomchit Onkaew, M.Sc. Student in Biotech., PSU.
Aran H-Kittikun, Asst. Prof., D. of Industrial Biotech., F. of Agro-Industry, PSU.
Suganya Chanthachum, D. of Food Tech., F. of Agro-Industry, PSU.
Corresponding e-mail : csuganya@ratree.psu.ac.th
Grant : Graduate School, PSU.
Presented : The 12th Annual Meeting of the Thai Society for Biotechnology "Biotechnology :
Impacts & Trends" Kanchanaburi, Thailand, 1-3 Novermber, 2000
Key words : bacteriocin, lactoperoxidase, Lactobacillus casei ssp. rhamnosus, Bacillus cereus
Bacteriocin from Lactobacillus casei ssp. rhamnosus (SN11) was produced and partially purified by centrifugation, ultrafiltration, and two steps of ammonium sulfate precipitation. Several concentrations of partially purified bacteriocin were used for preserving raw milk. It was found that
80 Au/ml of bacteriocin gave lowest TVC and Bacillus cereus count. When incubation of raw milk samples made at room temperature, maximum bactericidal activity of bacteriocin on TVC and B. Cereus were 5 and 4 hours, respectively. While incubation at 4oC were 5 and 4 days, respectively. Activation of lactoperoxidase system in raw milk was performed by adding NaSCN and H2O2 at 10 : 8 ppm. At room temperature, inhibition lactoperoxidase system TVC and B. cereus were 4 and 6
hours, respectively. While incubation at 4oC were 4 and 7 days, respectively. Activation activity of 2-hour-activated lactoperoxidase system prior to adding bacteriocin was greater than adding bacteriocin before activating lactoperoxidase system and activation of lactoperoxidase system and adding bac-teriocin in the same time. Treated milk samples were pasteurized at 63oC for 30 min and stored at
4oC. Shelf-life of the pasteurized milk sample was 12 days compared to 7 days of pasteurized control sample.
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