Abstract:

The quality changes and influencing factors of raw milk in and around Shanghai were studied by applying
correlation analysis, path analysis and multiple regression analysis. For this study, raw milk samples were collected from
local pastures almost over the whole year of 2009. The results showed that the changes of somatic cell count and aerobic
plate count in raw milk were significant. There was a significant positive corrleation between fat content and protein
content or freezing point, between protein content and freezing point or somatic cell count, and between aerobic plate
count and somatic cell count or average air temperature, whereas somatic cell count was very significantly negatively
correlated with average air temperature. At the same time, a regression model was established indicating aerobic plate
count (Y) versus temperature (X1), fat content (X2), protein content (X3) and average air humidity: Y = 7.592 ＋ 0.465X1 －
4.029X2 － 3.494X3 － 0.182X4.

Key words: raw milk, quality change, correlation analysis, multiple regression analysis