Abstract This study evaluated the influence of temperature and β-galactosidase concentration on lactose hydrolysis and on the composition of pasteurized goat milk. Goat milk was pasteurized at 75 °C/15 s and cooled to 10 °C and 30 °C, received 0 (control); 0.04%; 0.07%; 0.20% (v/v) β-galactosidase and was incubated for 5 h, followed by enzymatic inactivation at 85 °C. The hydrolysis degree, pH and acidity were evaluated hourly. Physico-chemical parameters were determined after hydrolysis. The maximum hydrolysis degree (100%) has been reached in 4 h when using 0.07% and 0.20% lactase concentrations at 30 °C; however, the minimum hydrolysis percentage of 70% has been reached at 10 °C for all lactase concentrations tested since 1 h of incubation. The degree of hydrolysis and the total acidity of pasteurized goat milk increased with temperature. Low lactase concentrations resulted in an increase in protein levels, total casein, density, total and defatted dry extract. Therefore, combination of low lactase levels and hydrolysis at 10 °C promoted positive changes in lactose-free pasteurized goat milk. This study was the first reporting the changes resulting from enzymatic hydrolysis in the composition of pasteurized goat milk.

Avaliou-se o efeito da adição do probiótico Lactobacillus paracasei e da fibra prebiótica inulina sobre o perfil de textura e as características sensoriais de queijo fresco cremoso. Três tratamentos de queijo fresco cremoso foram preparados em quintuplicata, em escala piloto, todos suplementados com uma cultura starter de Streptococcus thermophilus (T1, T2 e T3). L. paracasei subsp. paracasei foi adicionado em T1 e T2. Inulina foi adicionada em T2. O perfil de textura instrumental foi determinado após 1, 7, 14 e 21 dias de armazenamento. A análise sensorial foi conduzida aos 7 dias de armazenamento dos queijos. A presença de Lactobacillus paracasei nos queijos T1 e T2 e de inulina em T2 não alterou significativamente o perfil de textura (p>0,05). Os queijos T1 apresentaram a menor preferência na análise sensorial e diferiram significativamente de T2 e T3 (p<0,05), fato este atribuído ao sabor ácido, por parte dos provadores. Por outro lado, T2 foi o preferido, porém, não diferindo significativamente de T3 (p>0,05). A adição de inulina ao queijo fresco cremoso produzido com a suplementação de uma cepa potencialmente probiótica de Lactobacillus paracasei resultou em um produto com características adequadas e com propriedades funcionais agregadas.

The influence of the addition of a potential probiotic culture of Lactobacillus paracasei and of the prebiotic fiber inulin on the texture profile and on the sensory evaluation of probiotic and synbiotic fresh cream-cheeses was monitored. Three cheese-making trials were prepared in quintuplicate, all supplemented with a Streptococcus thermophilus starter culture (T1, T2 and T3). L. paracasei subsp. paracasei was added to T1 and T2, and inulin, to T2. The instrumental texture profile was determined after 1, 7, 14 and 21 days of storage of the cheeses. Sensory evaluation was performed after 7 days of storage. The presence of Lactobacillus paracasei in cheeses T1 and T2 and of inulin in cheeses T2 did not alter the texture profile significantly. Cheeses T1 were the least preferred in the sensory evaluation and differed significantly from T2 and T3, due to acidic taste, according to panelists. On the other hand, T2 was the most preferred one, though not significantly different from T3. The addition of the prebiotic ingredient inulin to fresh cream cheese processed with a potentially probiotic Lactobacillus paracasei strain resulted in a product with appropriate features and with aggregated functional properties.

O efeito de diferentes combinações de gomas sobre os parâmetros de textura instrumental de queijo tipo petit-suisse probiótico foi avaliado. Queijos petit-suisse foram produzidos utilizando-se massa-base de queijo quark preparada com o starter Streptococcus thermophilus e os probióticos Lactobacillus acidophilus e Bifidobacterium longum. Três formulações de queijo petit-suisse foram preparadas, a partir de massa-base de queijo quark adicionada de 0,75% do produto final da mistura de gomas - xantana (X), carragena (C), guar (G), pectina (P): F1 = 2,5X:2,5C:5G; F2 = 2X:3C:5P; F3 = 5C:5G. Os parâmetros avaliados após 1, 7, 14 e 21 dias de armazenamento do produto a 4±1ºC incluíram a contagem de probióticos, a textura instrumental, o pH e a umidade. As populações de probióticos mantiveram-se acima de 6,40 log UFC/g para L. acidophilus e de 7,30 log UFC/g para B. longum. Houve diferença significativa entre as formulações (p<0,05) para todos os parâmetros de textura, exceto a firmeza de F1. O pH e a umidade apresentaram comportamento semelhante para as três formulações. Dentre as formulações estudadas, F1 foi considerada a melhor, por sua firmeza mais estável durante o período de armazenamento.

The effect of different combinations of gums over texture parameters of probiotic petit-suisse cheese was evaluated. Petit-suisse cheeses were produced using Quark cheese-base prepared with the starter Streptococcus thermophilus and the probiotics Lactobacillus acidophilus and Bifidobacterium longum. Three formulations of petit-suisse were prepared, using the quark cheese-base added of 0.75% of the final product of the mixture of the hydrocolloids xanthan gum (X), carrageenan gum (C), guar gum (G), pectin (P): F1 = 2,5X:2,5C:5G; F2 = 2X:3C:5P; F3 = 5C:5G. Parameters evaluated after 1, 7, 14, and 21 days of storage of the product at 4±1ºC included microbial counts of probiotic microorganisms, instrumental texture parameters, pH and moisture. Probiotic counts were always above 6.40 log CFU/g for L. acidophilus and above 7.30 log CFU/g for B. longum. The formulations were significantly different (p<0.05) for all the texture parameters, except for firmness of F1. The pH and the moisture were similar for the three formulations. F1 was considered the best formulation, due to its more stable firmness during storage.

Com o objetivo de avaliar a conservação do extrato fluido da amêndoa de castanha-do-pará (conhecido como leite de castanha), executou-se a pasteurização com e sem adição de conservantes químicos e armazenou-se o produto sob refrigeração. Monitorou-se o produto, ao longo de um período de 180 dias de armazenamento, através de análises microbiológicas e das análises físico-químicas de acidez titulável e de pH. Os tratamentos que receberam conservantes químicos foram os mais estáveis microbiologicamente e obtiveram pH e acidez titulável mais equilibrados. A ausência de coliformes totais e fecais demonstrou a eficiência da pasteurização. Concluiu-se que a pasteurização só é um método viável de conservação do leite de castanha se associada à adição de conservantes e à refrigeração.

Pasteurization of a Brazil nut extract with and without addition of chemical preservatives and the storage of this product under refrigeration was performed to evaluate the conservation of this extract. The product was monitored during 180 days by microbiological, physical and chemical analysis including titratable acidity and pH. Treatments with chemical preservatives were microbiologically stable and titratable acidity and pH were equilibrated. Absence of total and fecal coliforms demonstrated the pasteurization efficiency. It is concluded that the pasteurization is only a viable method for preservation of the Brazil nut extract when associated with chemical preservatives and refrigeration.