ABSTRACT: Enhancing industrial sustainability by converting whey into alternative high value-added products is a scientific trend in food science and technology. However, without other ingredients, rennet, or sour, whey has an unappetizing flavor. This sensory challenge can be overcome by blending it with citrus flavor from orange juice. This study assessed a micro-filtered beverage from whey and orange juice without enzymatic treatment. Four formulations (27:10, 8.6:10, 2.4:10 and 1:10 v/v whey:juice ratio) were processed through a 1.4 μm microfiltration system with four different transmembrane pressures (1, 2, 3, and 4.15 bar) and then stored at 5 °C for 28 days. The micro-filtered beverage was analyzed for physicochemical, sensorial and microbial changes. It was possible overcome the technological challenges of orange juice microfiltration without enzymatic treatment with high transmembrane pressures. The whey:orange juice ratio was also decisive for permeation. A clear beverage with lower viscosity, turbidity, and protein levels was obtained, without altering mineral concentrations thus showing that the product has good capacity for hydration. The beverage presented good microbiological quality and remained stable for 28 days at 5 °C. Sensory evaluation data indicate that the beverage can be directed to young people and women, regardless of their physical activity. The combination of whey and orange juice can be explored industrially as a micro-filtered beverage, with satisfactory results of physicochemical, microbiological and sensory acceptance.

Resumo: 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 50oC 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.

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.