Qualidade do leite cru refrigerado e utilização dos tanques de resfriamento nas mesorregiões leste, agreste e central do Rio Grande do Norte

Abstract

Raw milk cooling in bulk tanks is a practice aimed at ensuring the quality of milk obtained from farms until they reach the industry. This study aimed to evaluate the quality of raw milk and the use of individual and collective cooling tanks in Rio Grande do Norte. The study was conducted in the Agreste, Central and Coastal mesoregions of the state of Rio Grande do Norte. Thirty-five individual and nine collective tanks participated in the study. The nominal capacity was obtained through the information indicated on the tank and the used capacity of the tank by measuring the level of milk stored in centimeters with the aid of a ruler. The percentage utilization of the tank capacity was obtained by the ratio between the used capacity and the nominal capacity. 155 raw milk samples were obtained directly from the cooling tank and kept refrigerated until the moment of analysis. The samples were submitted to physicochemical analysis to determine the fat, protein, lactose, degreased dry extract and total solids contents by infrared absorption spectrometry. Somatic Cell Count (SCC) of the samples was also performed by the flow cytometry method. Data were distributed according to the type of tank use (individual or collective) and in mesoregions (Agreste, Central and Coastal), to obtain descriptive statistical analysis and comparison of means. The individual tanks presented 33.0% in the average use, while the collective ones used 30.7%. The Central, Agreste and Coastal mesoregion tanks are used at 55.7, 29.6 and 60.0% of their capacity, respectively, indicating that the regions still have potential to embrace increased milk production. 40.0, 0.6, 4.8 and 51.5% of the samples were in non-compliance with current legislation, in the parameters Fat, Protein, Degreased Dry Extract and CCS, respectively. The overall mean SCC was 494.48 x 10³cels/ml, which indicates the compromised health of the mammary gland in dairy herds, which can lead to quantitative and qualitative loss of milk. There was a significant difference between the mesoregions in the mean milk fat, protein and lactose. It was concluded that the quality of refrigerated raw milk and the utilization of tanks in the Agreste, Central and Coastal mesoregions of Rio Grande do Norte are below the recommended. The existence of refrigeration tanks in bulk milk transport routes provides logistic efficiency in the sector, especially in terms of agility in collection and processing and in the preservation of product quality. Thus, these results can support actions by government agencies in order to make better use of bulk capacity in Agreste, Central and Litoral, without the need for new investments for the acquisition of refrigeration equipment.