Abstract The objective of this work was to evaluate microfluidic chip electrophoresis, known as lab-on-a-chip technique, for the detection of milk adulteration using cheese whey in comparison with SDS-PAGE. Raw, pasteurized, processed at an ultra-high temperature (UHT), and powdered milk samples received increasing concentrations of cheese whey (0, 1, 2.5, 5, 10, 20, 30, 50, and 100% v/v), and were subjected to lab-on-a-chip electrophoresis and SDS-PAGE to detect their mixtures. The lab-on-a-chip methodology was able to separate and quantify milk proteins. In addition, the tested technique is easy, rapid, sensitive, and can detect the addition of cheese whey in milk from the lowest level tested (1%) for milk proteins α-casein and β-casein.

Resumo O objetivo deste trabalho foi avaliar a eletroforese com dispositivo de microfluidos, conhecida como técnica lab-on-a-chip, para detecção de adulteração de leite com soro de queijo, em comparação ao SDS-PAGE. Amostras de leite cru, pasteurizado, processado em temperatura ultra-alta (UHT) e em pó receberam adição de soro de queijo em concentrações crescentes (0, 1, 2,5, 5, 10, 20, 30, 50 e 100% v/v) e foram submetidas a eletroforese lab-on-a-chip e SDS-PAGE para detectar suas misturas. A metodologia lab-on-a-chip foi capaz de separar e quantificar as proteínas do leite. Além disso, a técnica lab-on-a-chip é fácil, rápida, sensível e pode detectar adição de soro de queijo no leite do nível mais baixo testado (1%) para as proteínas do leite α-caseína e β-caseína.

In order to characterize the expression of genes associated with immune response mechanisms to mastitis, we quantified the relative expression of the IL-2, IL-4, IL-6, IL-8, IL-10, IFN-γ and TNF-α genes in milk cells of healthy cows and cows with clinical mastitis. Total RNA was extracted from milk cells of six Black and White Holstein (BW) cows and six Gyr cows, including three animals with and three without mastitis per breed. Gene expression was analyzed by real-time PCR. IL-10 gene expression was higher in the group of BW and Gyr cows with mastitis compared to animals free of infection from both breeds (p < 0.05). It was also higher in BW Holstein animals with clinical mastitis (p < 0.001), but it was not significant when Gyr cows with and without mastitis were compared (0.05 < p < 0.10). Among healthy cows, BW Holstein animals tended to present a higher expression of all genes studied, with a significant difference for the IL-2 and IFN-γ genes (p < 0.001). For animals with mastitis no significant difference in gene expression was observed between the two breeds. These findings suggest that animals with mastitis develop a preferentially cell-mediated immune response. Further studies including larger samples are necessary to better characterize the gene expression profile in cows with mastitis.