Abstract In this study, four milk substrates were analyzed to evaluate bovine Lactobacillus plantarum strain viability after 24 and 48 h of fermentation. In addition, cell viability, and post-acidification in transition milk fermented by these bacteria were assessed over a 60-d storage period at 4 and 25 °C. Significant reduction (30.9 %) of cell viability after 48 h of fermentation was observed for the formulation with whole milk. However, in fermented transition milk stored at 4 °C, cell viability and acidity were maintained at acceptable levels throughout the 60-d storage period. The viability of L. plantarum in fermented transition milk stored at 25 °C remained acceptable up to 50 d and minimum pH values were analyzed after 38 d of storage and maximum acidity levels after 56 d. Considering these results, transition milk may be preserved by L. plantarum fermentation as a substitute for milk in the artificial feed for calves as functional food.

Resumen En este estudio se analizaron cuatro sustratos de la leche para evaluar la viabilidad de la cepa de Lactobacillus plantarum de origen bovino después de 24 y 48 horas de fermentación. Además, se evaluó la viabilidad celular y la post-acidificación en la leche de transición fermentada por estas bacterias durante un periodo de almacenamiento de 60 días a 4 y 25 °C. Se observó una reducción significativa (de 30.9 %) de la viabilidad celular después de 48 horas de fermentación para la formulación con leche entera. Sin embargo, en la leche de transición fermentada almacenada a 4 °C, la viabilidad celular y la acidez se mantuvieron en niveles aceptables a lo largo del periodo de 60 días. La viabilidad de L. plantarum en la leche de transición fermentada permaneció aceptable hasta los 50 días, y se analizaron los valores de pH mínimo después de 38 días de almacenamiento y los niveles máximos de acidez después de 56 días. Tomando en cuenta estos resultados, la leche de transición puede ser conservada mediante la fermentación con L. plantarum como un sustituto de la leche en la alimentación artificial para terneros como alimento funcional.

Resumo O experimento visou avaliar o perfil de fermentação e acidez, pH e sinérese de iogurtes elaborados com leite contendo elevada e baixa contagem de células somáticas (CCS) e adicionados ou não de sólidos lácteos. No leite cru, coletado em seis dias distintos, avaliaram-se os teores de gordura, lactose, proteína, sólidos totais, extrato seco desengordurado, CCS e contagem bacteriana total (CBT). Submetidos à fermentação, verificaram-se o pH e acidez expressos em ácido láctico. No iogurte, mediram-se pH, acidez expressa em ácido lático e sinérese. O estudo foi conduzido em delineamento em blocos casualizados, com seis repetições e em parcelas subdivididas, tendo nas parcelas os tratamentos (níveis de CCS x adição ou não de sólidos) e, nas subparcelas, os tempos de fermentação e de armazenamento dos iogurtes. Os dados foram submetidos à análise de variância (ANOVA) e análises de regressão ou de correlação de Pearson, a 5% de probabilidade. Os níveis de CCS afetaram os teores de gordura e lactose do leite (p<0,05). Entretanto, assim como a adição de sólidos lácteos, não influenciaram o perfil de fermentação da cultura lática e a acidez, o pH e a sinérese dos iogurtes, sugerindo menor efeito dessas variáveis sobre a qualidade dos produtos.

Abstract The aim of this study was to evaluate the fermentation characteristics and yogurts made from milk with high or low milk somatic cell count (CCS) and added or not with milk solids. Raw milk was collected at six days and subjected to various electronic analyzes of protein, fat, lactose, total solids, CCS and total bacterial count (CBT). The profile of the fermentation was monitored by pH and acidity, expressed as lactic acid. Yoghurts were analyzed for pH, acidity expressed as lactic acid and syneresis of final product at different storage times. The experiment was conducted in a randomized block design, with six replicates and split plots with treatments in installments (CCS levels x added or not added milk solids) and fermentation times and storage periods for yogurts subplots. Data were subjected to analysis of variance (ANOVA), regression or Pearson Correlation analysis, according to the tests. The results showed that CCS levels had effects on some milk parameters (p<0,05). However, no effects were observed on the fermentation profile and characteristics of yoghurt during storage, according to the CCS levels or adding milk solids.

ABSTRACT The ability of pathogens to survive cheese ripening is a food-security concern. Therefore, this study aimed to evaluate the performance of two alternative methods of analysis of Listeria during the ripening of artisanal Minas cheese. These methods were tested and compared with the conventional method: Lateral Flow System™, in cheeses produced on laboratory scale using raw milk collected from different farms and inoculated with Listeria innocua; and VIDAS®-LMO, in cheese samples collected from different manufacturers in Serro, Minas Gerais, Brazil. These samples were also characterized in terms of lactic acid bacteria, coliforms and physical-chemical analysis. In the inoculated samples, L. innocua was detected by Lateral Flow System™ method with 33% false-negative and 68% accuracy results. L. innocua was only detected in the inoculated samples by the conventional method at 60-days of cheese ripening. L. monocytogenes was not detected by the conventional and the VIDAS®-LMO methods in cheese samples collected from different manufacturers, which impairs evaluating the performance of this alternative method. We concluded that the conventional method provided a better recovery of L. innocua throughout cheese ripening, being able to detect L. innocua at 60-day, aging period which is required by the current legislation.