Physical Performance And Protease Activity Of Skim And Whole Milk Additional Acetobacter Aceti And Inoculated Pseudomonas Fluorescens At Storage

Pasteurised milk spoiled due to activity of psychrotrophic bacteria. Acetobacter aceti which contain acetic acid can inhibit protease activity of psychrotrophic bacteria. To know inhibition of A. aceti, physical performance and protease activity of skim and whole milk additional A. aceti and inoculated Pseudomonas. fluorescens (treated milk) was observed Concentrations of A. aceti used were 0, 2.5, 5, 7.5 and 10 persen (w/v), and incubation was conducted at temperature 35oC for 2 hours. Physical performance was visually detected, and protease activity was detected by “Lowry” method. Times of storage used were 0 (4 days before expiry date), 4, 8, 12 and 16 days.The research results show that physical performances (colour, flavour, homogenity) on treated whole milk were better than that of skim milk at storage after expiry date. Protease activities of treated milk with various concentrations A. aceti were lower than that of control (without A. aceti). The higher the concentration of A. aceti, the higher the inhibition of protease activity of treated milk at storage. The inhibition of protease activity in treated milk and incubated was stronger than that without incubation. Protease activity in treated whole milk was lower than that in skim. The highest inhibition was found in treated milk with incubation, at storage, and concentration 10 persen A. aceti, with protease activities of treated whole milk were in the range 0.232-0.896 μM/mL.minute, and of skim were 0.236-1.206 μM/mL.minute. Berkala Penelitian Hayati. Edisi Khusus. P: 25-29