Microbiological quality of heat-treated milk during storage

Abstract

This study was carried out to evaluate the microbial load of heat treated milk during storage. Collected raw milk samples were subjected to heat treatment at 98°C for 1.87 min (High Pasteurization, HP) and 85°C for 40 min (Low Pasteurization, LP) in addition to Ultra High Temperature Treated (UHT) milk samples which were purchased from local market. Milk samples were subjected to microbial examination, titratable acidity and pH at 1, 10, 20 and 30 day intervals. Results indicated that total bacteria and lactic acid bacteria count significantly increased with time during storage period, together with increase in titratable acidity of all samples tested, while pH gradually decreased towards the end. The following genera were isolated from milk samples: Bacillus, Micrococcus, Saphylococcus, Enterobacter, Pseudomonas, Streptococcus, Pediococcus and Lactobacillus. © Asian Network for Scientific Information, 2009.