Effect of storage time and temperature on raw milk composition of dairy cattle in tropical conditions

Abstract

Storage milk before reaching processing unit is a difficult step in tropical conditions. Milk samples of 240 mL each were 
collected from 50 lactating cows from November 2010 to March 2011 and stored at room temperature and at +4°C in the 
refrigerator at consecutive hours. Milk composition was determined using infrared spectroscopy (FMA 2001, Miris AB, 
Sweden). The data were subjected to analysis of variance and the least square means were compared using Tukey test 
at p< 0.05. Raw milk fat and protein contents were higher in evening than morning milk (p< 0.05). Milk fat was 3.12 ± 
0.08 and 3.73 ± 0.08 % during morning and evening, respectively. It was similar for protein content, 2.77 ± 0.02 % and 
3.39 ± 0.02 %. After 24 h at room temperature (+28-30°C), milk fat significantly decreases to 3.08 ± 0.02 %. At +4°C, milk 
fat was 3.69 ± 0.08% after 24 and 3.68 ± 0.08 %after 120 h storage time. It was concluded that, cooling milk at room 
temperature is completely discarded after 24 hours. However, +4°C was adapted to cool milk during four (04) days 
without any significant damage.