Freezing of pasteurized goat milk and changes in milk during frozen storage

In this research, it was aimed to determine the microbiological, physical, chemical and sensory properties of frozen pasteurized whole fat goat milk after being transferred in to two different packaging size and stored frozen at two different temperatures and stored for three months.For this purpose, firstly raw and pasteurized goat milk properties were determined then they were transferred into two different packages (1/2 L and 1 L), later frozen at -15 and -35°C and were stored at -18 and -28°C for three months. During storage period (0, 30, 60 and 90 days) goat milk samples were investigated in terms of their microbiological (total aerobic mesophilic bacteria and coliform bacteria), chemical and biochemical properties (pH, titration acidity %, viscosity, sedimentation, acid value (ADV), oxidation and colour) and sensory characteristics.According to the results obtained, while the effect of storage time on the counts of coliform bacteria were found to be significant (p<0.05), there were no difference at total aerobic mesophilic bacteria count. Although there were no significant difference at titratable acidity and amount of vitamin E, significant differences (p<0.05) found for pH, sedimentation, oxidation and acid value. At the same time, colour values were observed to be significantly reduced (p<0.05) during freezing and storage period.In sensory evaluations, all tasted goat milk samples were approved, while 1 L packages liked more. During the storage time; odour, colour and appeareance of goat milk samples were not changed. On the other hand, 1 L packaged samples froze at -35ºC prefered more compared to other samples. Textural properties of goat milks were improved up to two months of storage, then deteriorations in texture were observed. Generally in the sensory evaluations, 1 L packages prefered by the panelists whilst physical properties of 1/2 L packages were also found to be still acceptable.