Efeito do binômio tempo e temperatura de conservação sobre o aspecto de qualidade higiênico-sanitário de leite de cabra

Abstract

The somatic cell count (SCC) is used as an indicator of milk quality for both cows and goats. The total count of bacteria (TCB) is of particular interest to the producer and to the industry, because it reflects the general conditions of hygiene in the production process of milk on the farm. The interference of time and temperature on the preservation of milk for analysis of SCC and TCB may measure the quality and hygienic-sanitary milk. The objective of this study was to evaluate the effect of the binomial time and storage temperature on the aspect of quality and hygienic-sanitary of goat's milk. We collected 20 samples of milk from goats in the races Saanen and Toggenburg in plastic bottles for analysis of SCC, TCB and ICB, totaling approximately 1.8 liters of each animal. After arrival of the samples in the laboratory, the milk was homogenized and distributed in 40 bottles sterilized, being 20 vials containing a compressed of preservative azidiol and 20 vials containing a compressed of preservative bronopol, totaling 320 aliquots with samples for each preservative, respectively. The bottles with milk samples were placed in refrigerators and incubators with different temperatures (5, 10, 20 and 30oC) and analyzed with 1, 3, 5 and 7 days after collection. The SCC and TCB were determined by the method of flow cytometry. The experimental design was a split-plot. The results of SCC, TCB and ICB were transformed into Neperian Logarithm for comparison of means. Was SNK test for comparison of means of SCC, TCB and ICB in accordance with the temperature and time of storage. The greatest impact on the variation of SCC was due to time within the temperature showing significant difference in temperatures 20 and 30oC, having a decrease in SCC 3.5 and 3.9% each day increase in time of storage at a temperature of 20 and 30oC, respectively. The greatest impact on the variation of TCB was due to the length of time within the temperature showing significant difference in temperatures 10 and 30oC, having a decrease in the TCB of 8.9% for each day of an increase in the time of storage at a temperature of 10oC and an increase in the TCB of 33.3% each day increase in time of storage at a temperature of 30oC. The greatest impact on the variation of the ICB was due to time within the temperature showing significant difference in temperatures 10 and 30oC, having a decrease in the ICB of 11.1% each day increase in long-term storage at a temperature of 10oC and an increase in the ICB of 44.3% each day to increase the time of storage at a temperature of 30oC. Samples stored at temperatures higher than 20oC can generate decrease in results of SCC and increase in results of TCB. The results show the need to forward the samples of milk for SCC and TCB under cooling and be done analysis up to seven days after collection.