Atividade lipolítica do leite com células somáticas ajustadas para diferentes níveis

Abstract

Estimou-se a origem da atividade lipolítica do leite com contagens de células somáticas (CCS) ajustadas para diferentes níveis. A partir de lotes de leite cru com baixa (100.000 cel/ml) e alta (1.000.000 cel/ml) CCS, formaram-se três tratamentos: A) leite com baixa CCS; B) leite com alta CCS; C) leite originalmente com baixa CCS e com adição de células somáticas. O leite foi submetido à pasteurização e armazenado por 21 dias sob refrigeração a 6ºC. Durante o período de armazenamento, foram coletadas amostras nos dias 1, 7, 14 e 21 para avaliação da concentração de ácidos graxos livres (AGL). Não foi observado efeito de tratamento sobre a concentração de AGL, durante todo o período de armazenamento e nem em cada dia de coleta isoladamente, cujas médias de AGL, após 21 dias, foram de 0,181; 0,159 e 0,153meq/kg, respectivamente, para os tratamentos A, B e C. Observou-se efeito do tempo de armazenamento sobre a concentração de AGL do leite, independentemente dos tratamentos, com teores de AGL de 0,121meq/kg para o dia 1 e de 0,219 para o dia 21. Pode-se concluir que, independentemente da contagem de células somáticas do leite cru, ocorre aumento da lipólise do leite pasteurizado durante o período de armazenamento. A adição de células somáticas ao leite, originalmente com baixa CCS, não aumentou a taxa de lipólise durante o armazenamento refrigerado.

Milk with different somatic cells counts and the physicochemical, microbiological characteristics and fatty acid profile of pasteurised milk cream: is there an association?

“…However, this decrease did not affect ( P > 0.05) the concentration of long‐chain fatty acids (LCFA) in creams from all treatments. A possible explanation for the absence of extended lipolysis in high SCC creams could be the separation of somatic cells from the cream during the centrifugation process, as the cells have higher density and therefore remain in the skim milk (Santos et al ., ).…”

Effect of high somatic cell counts on the sensory acceptance and consumption intent of pasteurized milk and coalho cheese

“…Pasteurized or UHT milk obtained from raw milk with high SCC content (from 500.000 cells/mL) is characterized by developing flavor defects. Some of the consequences are the proteolysis of milk due to the degradation of beta-casein, and lipolysis which can negatively affect the quality of the product and lead to a lower nutritional value (Fernandes et al 2008a;2008b;Santos et al, 2007). These defects may be associated with the plasmin levels, the endogenous enzyme of milk, and its inactive form plasminogen, which have their proteolytic activity associated with SCC (Ismail & Nielsen, 2010) and affects stability and taste of the fluid milk.…”

“…This occurs due to the action of lipases originating from the SCC on triacylglycerides, resulting in the appearance of sensory defects such as rancidity. Even after pasteurization, milk with high SCC shows an increase in lipolytic activity, and the occurrence of rancidity can be identified in sensory analysis tests (Santos et al, 2007) when the free fatty acid concentrations are greater than 0.200 meq/kg of milk (Santos et al, 2003), and these defects were also additionally related to a higher proteolysis rate in milk with high SCC (849,000 cell/mL). It is possible to increase the shelf life of refrigerated pasteurized milk when using milk with low SCC (45,000 cell/mL) associated with care during handling and refrigeration, avoiding the development of rancidity or bitter taste due to the release of peptides mainly originating from alpha S1-and beta-casein, which can lead to important sensory changes in milk (Ivanov et al, 2020).…”

Effect of seasonal conditions and milk management practices on bulk milk quality in Minas Gerais State - Brazil

“…According to Le Roux et al (2003) and Li et al (2014), a decrease in the protein concentrations, especially casein, may be promoted by the action of bacterial proteases and a decreased capacity to synthesis milk can occur due to damage caused to the secretory epithelium. Also, a reduced fat content may be due to the action of lipases from the leukocyte origin (Santos et al, 2007;Li et al, 2014).…”