ChileanJAR

An investigation was carried out in order to: 1) measure the degree of bacterial contamination atributed to the pasage of milk through the milking equipament; 2) The effect of cooling the milk through a surfase milk cooler (SMC) and 3) The effect of period of storage on the bacteriological quality of milk. The following methods of milk quality evaluation were compared and correlated in single relationships: titratable acidity, pH, time for reduction of methylene Blue (TRMR) and bacterial count. Milk samples were collected after at: a) hand milking directly into a sterilized matrass; b) mechanical milking with the milk being collected before entering of the SMC; c) mechanical milking with the milk being collected after passing through the SMC. All milk samples were maintained in sterilized glassbottles and sub-samples were taken after 0, 1, 2 and 3 hours post collection for analysis.
The milk optained by a) ranked best in TRMB, baterilogical count and titratable acidity. The TRMB of milk collected by mechanical equipment was significantly improved by cooling in SMC. The storage time results in a progressive deteriration of milk quality and this effect was more notorious in milk collected by mechanical means. Coliform bacteria were found in milk sample b), and c). There was at high relationship (r=-0.78, P=0.019 between TRMB and bacterial count.