Chemical and microbiological quality assessment of raw and processed liquid market milks of Bangladesh.

Twelve different liquid market milks of Bangladesh were examined to evaluate their chemical and sanitary quality. Six of these were open raw milk bought from local daily markets and the other six were processed packet milk (both pasteurized and UHT [Ultra High Temperature] - processed) available in shops. The twelve samples were examined for the determination of percentage of water, total soluble solids (TSS), fat, solids-non-fat (SNF), lactose, protein, and ash; measurement of titratable acidity; detection of adulterants; enumeration of total bacterial count, staphylococcal, coliform, fecal coliform, Salmonella and Shigella, Aeromonas hydrophila, and psychrophilic count. Results revealed that most of the raw and pasteurized milks were substandard in both chemical and sanitary quality whereas the quality of UHT-treated milks was excellent. Majority of the raw and pasteurized milks contained fair amounts of lactose, protein and ash, but a number of these had lesser amount of fat. All the raw and pasteurized milks were found to be contaminated with bacterial loads exceeding the acceptable limit. The indicator organisms i.e. coliforms and fecal coliforms were present in most of these samples in large numbers. Pathogenic bacterial genera (Aeromonas, Salmonella, and Staphylococcus) were also identified in some of these. High counts of psychrophilic bacteria were also found in the raw and pasteurized milk. But none of the UHT-processed milks contained any bacteria. Water had been added to five raw and one pasteurized milk whereas sucrose was found in five of the six heat-treated samples.