Effect of Different Rinsing Methods on the Number of Microorganisms on the Surface of Milk Churn in Dairy Processing Plant

Abstract

The objective of this research was to determine effect of different rinsing methods on total bacteria counts of internal surfaces of milk churns which were employed in a dairy processing plant. There were 4 rinsing methods including I) room temperature water rinsing (27⁰C), II) hot water (75⁰C) rinsing, III) room-hot temperature water rinsing and IV) commercial detergent rinsing. Moreover, the change in contaminated total bacteria numbers of used milk churns was also investigated after 0 15 30 45 60 75 90 120 and 180 minutes of incubation. The results showed that different rinsing methods were significantly different (p≤0.05) in the numbers of bacteria on internal surfaces of milk churns as well as percentages survival. Hence, the rinsing by commercial detergent solution (IV) was recommended which it had lowest percentages of survival bacteria (72.78%).  Furthermore, the change in number of contaminated total bacteria counts of used milk churns was also determined. The result showed that the bacterial numbers were rather constant at 4.30 log CFU/mL after 75 minutes of incubation.