Effect of operating parameters and storage time on the quality and microbial characteristics functional milk-carrot drink

The aim of the research was to study the effect of operation parameters and storage time on quality and microbial characteristics of functional milk-carrot drink. For this purpose, the milk-carrot drinks were prepared in different concentrations of carrot juice (10, 20, 30, 40 and 50 percent). After pasteurization at 65, 70 and 75 °C for 30 minute, quialty characteristics (total acidity, pH, dry matter, total carotenoid and total protein), microbial test (Coliform) and pasteurization adequancy test were investigated during storage time (1, 4, 7, 10 and 13th day) in refregration temperature (4 °C). The results showed that pasturized milk-carrot samples at 70 °C during different days were the best samples considering pH, total acidity, dry matter and organoleptic properties in comparison with other treatments. In the case of total carotenoid, treatmentsin 65 and 75 °C had the highest and lowest caretonoid contents respectively. Pasturization temperature and storage time (1, 4, 7, 10 and 13th day) had not significant effects on total protein content of samples with different concentration of carrot juice. The pasteurization adequacy test showed that all of time-temperature combinations could inactivate alkaline phosphatase anzyme activity.