Sanitary aspects and technological challenges of whole milk microfiltration at low temperatures

Abstract

-The objective of this work was to evaluate the effects of whole milk microfiltration at low temperatures on bacterial counts and on its shelf life. The microfiltration process was evaluated at two temperatures (30 and 50ºC) and compared with the slow pasteurization process. Both slow pasteurization and microfiltration reduced the initial counts of aerobic mesophilic and psychrotrophic bacteria, as well as total coliforms in whole milk. Microfiltration at 50ºC was as effective as the pasteurization process, since it reduced the initial count of aerobic mesophilic bacteria in 4.4 log cycles; increased the product's shelf life, which reached 30 days without exceeding 1,000 CFU mL -1; and eliminated coliform counts at the temperatures of 35 and 45ºC, established by the Brazilian legislation. Microfiltration at 30°C reduced the aerobic mesophilic bacteria counts by 2.2 log cycles; however, Escherichia coli was found in the product, which exhibited a shelf life of less than five days. Therefore, microfiltration at 30ºC can be associated with thermal treatments, but, when applied alone, it shows unsatisfactory results.Index terms: Escherichia coli, membrane, microbiological quality, pasteurization, shelf life. Aspectos sanitários e desafios tecnológicos da microfiltração de leite integral a baixas temperaturasResumo -O objetivo deste trabalho foi avaliar os efeitos da microfiltração do leite integral a baixas temperaturas, nas contagens bacterianas e na sua vida de prateleira. O processo de microfiltração foi avaliado a duas temperaturas (30 e 50ºC) e comparado à pasteurização lenta. Tanto a pasteurização quanto a microfiltração reduziram as contagens iniciais de bactérias aeróbias mesófilas e psicrotróficas, bem como a de coliformes totais no leite integral. A microfiltração a 50 o C foi tão efetiva quanto o processo de pasteurização, tendo reduzido as contagens iniciais de bactérias aeróbias mesófilas em 4,4 ciclos logarítimicos; aumentado a durabilidade do produto, que atingiu 30 dias sem exceder 1.000 UFC mL -1 ; e eliminado coliformes nas temperaturas de 35 e 45ºC, estabelecidas pela legislação brasileira. A microfiltração a 30ºC reduziu as contagens iniciais de bactérias aeróbias mesófilas em 2,2 ciclos logarítimicos; entretanto, Escherichia coli foi detectada no produto, que apresentou vida útil inferior a cinco dias. Portanto, a microfiltração a 30ºC pode ser associada a tratamentos térmicos, mas, quando aplicada isoladamente, apresenta resultados insatisfatórios.Termos para indexação: Escherichia coli, membrana, qualidade microbiológica, pasteurização, vida de prateleira.

The Influence of Whey Protein Heating Parameters on Their Susceptibility to Digestive Enzymes and the Antidiabetic Activity of Hydrolysates

“…This was relevant to the generally used-optimum concentration range of the tested compounds, which was between 1.0 × 10 −4 and 0.5 mg/mL [ 27 , 32 , 38 ]. At the concentrations of protein hydrolysates below or equal to 2.5 mg/mL, WPI and the α-LA hydrolysate heated at 65 °C for 30 min, known as a low-temperature long time (LTLT) pasteurization [ 40 ], induced better cell viability compared to the control baseline. However, when heating was at 75 and 85 °C, each protein hydrolysate did not clearly induce cell viability.…”