Efeito das condições de armazenamento de amostras de leite no índice de caseinomacropeptídeo

Abstract

The objective of the present work was to evaluate the influence of temperature and storage time of samples of raw milk, pasteurized and UHT milk, compared to the ratio of CMP by HPLC. The parameters evaluated were the peak height of CMP by HPLC, acidity, pH, the enumeration of micro-organisms aerobic mesophilic and psychrotrophic. Six samples of raw milk were collected, subdivided into sterile plastic bottles and stored at temperatures of 6°C and -12°C for a maximum period of four days. Analyses of chemical composition and somatic cell counts were made on electronic equipment Bentley CombSystem 2300. Pasteurized milk was obtained from the raw milk samples that were subjected to a temperature of 65°C for 30 minutes. Posteriorly were subdivided into sterile plastic bottles and stored at temperatures of 6°C and -12°C for a maximum period of eight days. It was analyzed also the absence of Salmonella spp., the most probable number (MPN) of coliforms at 30/35ºC and 45ºC and the enzymes activity of alkaline phosphatase and peroxidase. UHT milk samples from six production batches were stored in the packaging itself, at temperatures of 21, 6 and -12°C for a maximum period of 120 days. The study design was randomized blocks with factorial arrangement. Noting the hierarchical system in a 2x5 factorial arrangement for the samples of raw milk and pasteurized. Adopted for whole milk UHT the 3x5 factorial design. Were performed six repetitions of the experiment. The treatments were subjected to analysis of variance and subsequent comparison of their means, through the Student-Newman-Keuls (SNK) at the 5% significance level. It was concluded that the samples of raw milk stored at 6°C up to four days and pasteurized milk stored at -12°C up to eight days may be assessed in relation to an index of CMP without prejudging the results. The detection of fraud by the addition of whey in UHT milk so can be detected only after the filling phase due to proteolysis that occurs during the period of validity of the milk. If it is not possible for immediate consideration, it is recommended that samples be frozen. The search index CMP by HPLC is very precise (CV=1.9%) and indifferent to the conditions of storage and content of the CMP samples.