ChileanJAR

In a trial done at La Platina Research Station (INIA), Santiago, Chile, the influence of the temperature used for washing the milking machine on the microbial concentration of refrigerated milk was studied. Two treatments were established, according to the temperature of the cleaning solution, i.e. 80ºC (T1) and 30ºC (T2). Ten succesive replications were done for each treatment, in each milk sampling, at 0, 24 and 36 hr of refrigeration. Total bacteria (RBT), coliforms (RC) and psychrotrophics (RP) were counted. The effect of the higienic treatment of the milking machine, as well as the time effect, were analized through a split plot design, where initial contamination was the main plot. Microbial content of milk was affected by temperature of the detergent solution (P < 0.05); values for T1 and T2 were: RBT = 10,360a and 20,483b; RC = 112a and 957b; RP =1,670a and 5,950b. The time of refrigerated storage, analized independently for T1 and T2, affected (P < 0,01). the bacterial concentration with the following values in T1, at 0, 24, and 36 hr: RBT = 8,040a; 9,530ab; and 13,510b; RC = 117a, 110a, and 110a; RP = 1,080a; 1,310a; and 2,620b. Values for T2 were: RBT = 16,730A; 19,290AB; and 25,430B; RC = 860A, 930A, and 1,080A; RP = 2,490A; 5,820AB; and 9,540B. It was concluded that the use of detergent solutions at 80ºC would improve the bacterial quality of milk, although a temperature of 30ºC was also satisfactory.