Multivariate optimization of Staphylococcus xylosus AD1biomass production using sugarcane molasses plus yeast extract and soybean meal

Staphylococcus xylosusis a microorganism that has important physiological and technological characteristics that make it suitable for use as a starter culture in fermented meat products. For the development of these products in the food industry, it is necessary to produce biomass by the multiplication of starter cultures using low-cost media. This study developed a culture medium based on sugarcane molasses (SCM) supplemented with yeast extract (YE) and soybean meal (SM) to produce S. xylosusAD1 biomass employing a Box Behnken multivariateoptimization design,usingthe best concentrations of the constituents of the culture medium for S. xylosusAD1 growth. By combining the mathematical models by the desirability function, it was possible to establish the optimal condition for the maximum production of viable cells and biomass. The optimal experimental condition was found when the fermentative process medium was composed of 10% SCM, 2% YE and 4% SM. In addition, the results of all experiments, except for the medium formulated with only SCM,presented a better performance than the commercial medium Brain Heart Infusion for the growth of S. xylosusAD1. The culture medium with agro-industrial byproduct (SCM) supplemented with YE and SM is an excellent alternative for producing S. xylosusAD1 biomass.

Microbiological and physicochemical characterization of the raw milk and the colonial type cheese from the Northwestern Frontier region of Rio Grande do Sul, Brazil / Caracterização microbiológica e físico-química de leite cru e queijo colonial da região Fronteira Noroeste do Rio Grande do Sul, Brasil

This study aimed at evaluating the microbiological and physicochemical characteristics of raw milk and colonial type cheese from Northwestern Frontier region of Rio Grande do Sul, Brazil. For this purpose, the samples were collected in January and July. Microbiological analyses (aerobic mesophilic bacteria, total/thermotolerant coliform, coagulase-positive Staphylococcus, Salmonella spp. and Listeria monocytogenes, lactic acid bacteria) and physicochemical assays (pH, acidity, total solids, protein, fat, aw, moisture, NaCl) were performed. The milk and cheese samples showed low microbiological quality because high counting of aerobic mesophilic bacteria, total/thermotolerant coliform and coagulase-positive Staphylococcus were detected. High counting of lactic acid bacteria was observed. However, neither Salmonella spp. nor Listeria monocytogenes was found. The standard deviations above one (1.0) in the fat, protein, moisture and salt contents indicated that no standard procedure was followed for producing the local cheese. The sample collection period caused differences in the microbiota, total solids of milk and cheese moisture contents, aw and salt. The maturation period did not significantly influenced on the microbial counts, but it provided an increase in protein contents and a decrease in aw value in cheese samples collected in July.

Este estudo avaliou as características microbiológicas e físico-químicas de leite cru e queijo colonial da região Fronteira Noroeste do Rio Grande do Sul, Brasil. Para isto, foram feitas coletas de amostras em janeiro e julho. Análises microbiológicas (bactérias aeróbias mesófilas, coliformes totais e termotolerantes, Staphylococcus coagulase positiva, Salmonella spp. e Listeria monocytogenes, bactérias ácido lácticas) e físico-químicas(pH, acidez, sólidos totais, proteína, lipídeos, Aa, umidade, NaCl) foram realizadas. As amostras de leitee de queijo indicaram baixa qualidade microbiológica, pois houve detecção de altos níveis de bactériasmesófilas, coliformes totais e termotolerantes e Staphylococcus coagulase positiva. Altas contagens de bactérias ácido láticas foram observadas. Entretanto, não foi detectada a presença de Salmonella spp. eListeria monocytogenes. O desvio padrão acima de um (1,0) nos conteúdos de lipídeos, proteínas, umidade e sal indicou que não houve seguimento do procedimento padrão estabelecido na produção local de queijos. O período de coleta de amostras resultou em diferenças nas análises de microbiota, sólidos totais do leitee dos queijos, o teor de umidade, Aa e sal. O período de maturação não causou significativa influênciasobre as contagens microbianas, mas promoveu aumento no conteúdo de proteína e diminuição na Aa dos queijos coletados em julho.

Caracterização físico-química de méis de Apis mellifera L. da região noroeste do Estado do Rio Grande do Sul / Physicochemical characterization of Apis mellifera L. honeys from the northwest region of Rio Grande do Sul State

O objetivo deste trabalho foi determinar a composição físico-química de méis de Apis mellifera L. produzidos em dois anos consecutivos na região noroeste do Estado do Rio Grande do Sul, Brasil. As características físico-químicas de 36 amostras de mel foram comparadas utilizando o teste T de Student e a adequação aos padrões da legislação brasileira da qualidade do mel foi verificada. Os resultados das análises dos méis variaram para as características analisadas conforme segue: pH (3,3-4,4), umidade (14,7-19,8 por cento), acidez total (16,9-49,2meq kg-1), hidroximetilfurfural (0,15-48,3mg kg-1), açúcares redutores (60,1-75,9 por cento), açúcares não-redutores (1,35-5,99 por cento), cinzas (0,05-0,47 por cento) e sólidos insolúveis (0,016-0,27g kg-1). A análise estatística das amostras de mel produzidas em dois anos consecutivos mostrou que houve diferença significativa na umidade, na acidez e na hidroximetilfurfural. Os méis produzidos nesta região apresentam boa qualidade e características físico-químicas compatíveis aos padrões da legislação brasileira.

The objective of this research was to determine the physicochemical composition of Apis mellifera L. honeys produced in two consecutive years in the northwest region of Rio Grande do Sul State, Brazil. The physicochemical characteristics of 36 honey samples were compared using Student's T-test and their adequacy to standards established by the Brazilian legislation for honey quality was checked. The results varied as follows: pH (3.3-4.4), moisture (14.7-19.8 percent), acidity (16.9-49.2meq kg-1), hydroxymethylfurfural content (0.15-48.3mg kg-1), reducing sugar (60.1-75.9 percent), non-reducing sugar (1.35-5.99 percent), ashes (0.05-0.47 percent) and solids non-soluble in water (0.016-0.27g kg-1). The statistical analyses of honey samples produced in two consecutive years showed that the moisture, acidity and hydroxymethylfurfural content varied significantly. The honey samples produced in this region were in accordance with the Brazilian legislation for honey quality.