Abstract

Ammara Hassan, Imran Amjad and Shahid Mahmood

The aim of the study was to diagnose physiochemical, microbiological, sensorial changes and to differentiate the milk collection systems of the commercial milk market competitor during storage of 12 weeks. The parameters used for physicochemical analysis are; sedimentation, solids non fats (SNF), fat and protein %, total titratable acidity and pH and for microbiological analysis; total plate, coliform, Bacillus cereus and Bacillus subtilus, Escherichia coli and spore forming bacterial count were determined. Colour, taste and aroma were observed during storage. The results strongly reflect an increase in sedimentation value with the ice mixing or dilution before processing which disturbed the salt balance, protein charges and natural emulsion. There was increase in acidity and sedimentation of milk but pH, % of fat contents, SNF (solids non fats) and proteins decreased during storage. The negative changes occurred in colour, aroma and flavor with reference to these physiochemical changes. Microbial counts for coliforms (e.g. E. coli), B. cereus, B. subtilis and heat resistant spores forming bacteria were zero. These all factors collectively limited the shelf life of UHT (ultra-high temperature) milk.