Abstract
This study was carried out to investigate the changes of physical and chemical properties according to the preserving periods and temperature in heat-treated market milks ($130^{\circ}C$, 2 sec). The market ilks were divided into 3 experimental groups, that is $4^{\circ}C$, $15^{\circ}C$ and $30^{\circ}C$ according to the preserving temperature during 7 days. There were analysed fat, protein, lactose, total solids, solids-not-fat, specific gravity and acid value of market milks in each experimental group. These observations indicated that heat-treated market milks ($130^{\circ}C$, 2 sec) may be acceptable physically and chemically after 7 days at $4^{\circ}C$. The results obtained were summarized as follows ; 1. Total microorganisms in market milks were found 12$\times$$10^1$ cells at 1st day Coliform and pathogenic bacteria were not detected. 2. Milk fats tended to decrease 3.69% to 3.48% according to the time lapsed in all experimental groups without concerning to the storage temperature. 3. Milk proteins were slowly decreased 3.18% to 3.13% according to the time lapsed without concerning to the storage temperature. 4. Milk lactose was slightly increased 4.41% to 4.55% in all experimental groups. 5. Specific gravity in market milks was 1.0316 to 1.0299, and showed no changes according to the preserving periods and temperature. 6. Total solids and solids-not-fat in market milks were slightly decreased 12.30 to 12.05 and 8.55 to 8.40. 7. Acid values were dramatically increased 0.1289 to 0.3116 at $30^{\circ}C$ storage group, while tended to be stable at $4^{\circ}C$ storage group for 7 days.