ChileanJAR

Milk samples of 25 farms of the Region Metropolitana and the VI Region of Chile, were taken at the beginning (0 hr) and at the end (36 hr) of storage in the cooling tanks. Subsequently they were transported at low temperature to the laboratory, to determine the counts/ml for the total bacteria (RBT). coliform bacteria (RC). and psychrotrophic bacteria (RP). Results were statistically studied through ANOVA, correlation and regression analyses. The means at 0 and 36 hr were: RBT = 131,368a and 287,956b (P < 0,05); RC = 9,780a and 9,708a; RP = 35,544a and 323,524b (P < 0,05). Considering different standards for alternate day collection, the bacteriological quality of milk would be appropriate in 8 to 60, 12 to 36, 16 to 40% of the samples, when assessed according to RBT, RC and RP, respectively. The correlation coefficients between initial and final counts were; RBT: 0.79 (P < 0.001). RC: 0.74 (P < 0.001) and RP: 0.74 (P < 0.001). It was concluded that the alternate day milk collection would be affected principally by RP and RC, and to a lesser extent, by RBT. The final microbialload of milk would depend on the initial counts, showing variability among farms, specially as far as psychrotrophics are concerned.