Composition and physical-chemical characteristics of unstable non-acid milk received in a dairy plant of the State of São Paulo, Brazil

Abstract

The objective of this study was to determine the occurrence, composition, physical-chemical characteristics and somatic cell count of milks identified as unstable non acid received in a dairy plant located in the Northeast region of São Paulo state. The sampling covered all dairy farms that provide milk to the dairy plant, during the rainy season and dry season of 2007. For the identification of unstable non acid milks, it was considered the bulked milk sample from each farm that showed instability to the ethanol test at 72% (v/v) and acidity less than 18o D. From the total samples unstable to ethanol at 72% (v/v), 64.8% were identified as unstable non acid milk. The occurrence of unstable non acid varied according to sampling period, indicating a seasonal influence on the occurrence of this problem in the herds analyzed. In the dry season, the occurrence of unstable non acid was higher, coinciding with the period in which the availability of good quality pasture is reduced due to reduction in the volume of rainfall. Also in the dry period, there were greater levels of fat and somatic cell count, along with a decrease in the concentrations of total protein and lactose. Results of this trial showed that the occurrence of unstable non acid is frequent in the dairy herds of the region studied, is influenced by seasonal variations and is associated to changes in milk composition, which may cause significant losses to the dairy industry and dairy farmers.