Lactobacilli In Cheese Research Articles

Petit-Suisse Cheese Production with Addition of Probiotic <i>Lactobacillus</i> <i>casei</i>

Growing concern to increase life expectancy has promoted several studies in the field of nutrition, especially those on food and their effects on the human body. Assays have been performed to improve their nutritional quality. In fact, there is considerable interest in encouraging development of new ingredients, with the innovation in food products and the establishment of new market niches for these ingredients. The global market for functional foods is growing and always envisages new products with functional technological and physiological characteristics. The petitsuisse cheese is a product of high nutritional value, rich in calcium, phosphorus and fat-soluble vitamins, with a high percentage of milk proteins, coupled to excellent digestion and assimilation by the human body. Current assay describes the production of a petit-suisse cheese to which was added the probiotic Lactobacillus casei BGP 93, and determines the physical, chemical and microbiological viability of lactobacilli in cheese during storage period. Levels of protein, fat in the dry extract, moisture and pH were analyzed for physical and chemical parameters; likewise, detection of coliforms, Staphylococcus, Salmonella, Listeria monocytogenes, and yeasts and molds was performed for microbiological parameters; monitoring of the viability of Lactobacillus casei BGP 93 during its life time was conducted. The petit-suisse cheese proved to be a good vehicle for the addition of probiotic microorganism. Lactobacillus casei remained viable during shelf life even with decreasing pH, and may be considered a functional product during 30 days of storage.

Quantitative detection and identification of tyramine-producing enterococci and lactobacilli in cheese by multiplex qPCR

Tyramine is the most abundant biogenic amine in fermented dairy products, in which it is produced through the microbial enzymatic decarboxylation of tyrosine. This activity has been detected in a variety of lactic acid bacteria mainly belonging to the genera Enterococcus and Lactobacillus. This paper describes a culture-independent qPCR method, based on the specific amplification of the tdc gene, for the detection, quantification and identification of bacteria with the ability to produce tyramine. This method was found to be specific and to show a wide dynamic range, thus allowing the quantification of these tdc+ bacterial groups among the complex microbiota of cheese. tdc qPCR was used to follow the development of tdc+ microbiota during the manufacture of a blue-veined cheese (Cabrales) made from raw milk. In this type of cheese, tdc+ enterococci seem to be responsible for the high concentrations of tyramine detected. The method was also used to identify and quantify tdc+ enterococci and lactobacilli in 18 commercially available cheeses. Different types and numbers of these microorganisms were found. Their relationships with the concentration of tyramine and technological factors are discussed.

Influence of lamb rennet paste on composition and proteolysis during ripening of Pecorino foggiano cheese

Rennet pastes produced by lambs subjected to three different feeding systems (mother suckling [MS], artificial rearing [AR], and artificial rearing with Lactobacillus acidophilus supplementation [ARLB]) and slaughtered at two different ages (20 and 40 d) were used for the manufacture of Pecorino foggiano cheese. Composition and proteolysis during ripening of Pecorino foggiano cheese (four replicates batches) were analyzed. Proteolysis was greater in cheeses made with rennet pastes from lambs slaughtered at 20 d, as shown by analysis of nitrogen fractions (water-soluble N and proteose peptones). Supplementation of milk substitute with L. acidophilus may have influenced the growth dynamics of lactic acid bacteria in the rennet pastes, with positive effects on levels of lactobacilli in cheese at the beginning of the ripening time. Lower pH values in ARLB cheese during ripening, together with higher cell loads, suggest that supplementation of milk replacer with L. acidophilus resulted in higher proteolytic activity, as also confirmed by the composition of the pH 4.6—insoluble nitrogen fraction. No differences were found in total concentration of free amino acids among the experimental cheeses; phenylalanine, isoleucine, leucine, lysine were found at the highest levels. The addition of probiotic bacteria to milk substitute in lamb rearing appears to give good-quality lamb rennet paste.

Detection, Growth, and Amine-Producing Capacity of Lactobacilli in Cheese

A differential plating medium was developed to detect decarboxylating lactobacilli in cheese. With this medium, 15 cheeses made from raw milk were investigated for the presence of these bacteria. Five histidine-decarboxylating strains and one tyrosine-decarboxylating strain were isolated. The isolates were identified with the API 50L system. Accordingly, each of the five histidine-decarboxylating strains was identified as Lactobacillus buchneri, whereas the tyrosine-decarboxylating strain is a representative of Lactobacillus brevis. Cheesemaking experiments using a low inoculum concentration of the histidinedecarboxylating L. buchneri strain St2A (0.2 CFU/ml of milk) showed that, under conditions of accelerated proteolysis, histamine may accumulate rapidly; after 3 months of ripening, 410 mg/kg was found. An inoculum concentration of 5 CFU/ml gave rise to the formation of 1,060 mg/kg.

A comparative study of two media for the enumeration of lactobacilli in cheese

A comparative study of two media for the enumeration of lactobacilli in cheese

728. Lactobacilli in the air of creameries

Lactobacilli occur in large numbers in cheese (1), even when the milk used for cheesemaking has been pasteurized (2) and therefore contains very few or no lactobacilli. The lactobacilli in cheese must enter during cheese-making, and a potential source of these organisms is the air of the creamery. Olson & Hammer (3), although not concerned directly with lactobacilli, showed that the numbers of bacteria in the air of dairy plants fluctuated with weather conditions. Naylor & Sharpe(4) found lactobacilli in the air of the Experimental Dairy at the National Institute for Research in Dairying: some strains were identical with others isolated from cheese, but there was frequently no correlation in type of lactobacilli from the air with those from cheese. Thus, ‘cheese types’ were found in the air some months before or after the cheese was made, which seemed to indicate contamination of the air from sources within the dairy. To obtain further information regarding the lactobacillus flora of the air the following investigation was made.

733. Lactobacilli in Cheddar cheese: III. The source of lactobacilli in cheese

Lactobacilli occur in large numbers in cheese (1,2,3,4) and may be responsible for or influence the formation of flavour. It is therefore desirable to find the source of the lactobacilli and the route by which they enter the cheese, so that the cheese flora may be controlled

The Production of a Growth Inhibitor by Lactic Streptococci1,2

Summary Nine strains of Streptococcus lactis and Streptococcus cremoris and three commercial starter cultures were found to produce a heat stable substance that inhibited growth of Lactobacillus casei . The material also inhibited certain strains of lactic streptococci, although to a lesser extent than it restrained growth of the rods. The lactic streptococci varied considerably in their ability to produce the inhibitor; also, strains of L. casei differed markedly in their susceptibility to inhibition. When given sufficient time, the rod cultures overcame the effect of the inhibitor. Most of the inhibitor was formed by the lactic streptococci during the first 24 hr. of their growth in broth, although its concentration continued to increase slowly for as long as 60 hr. The culture medium used for growing the streptococci had a marked effect on the amount of inhibitor produced. Whey and curd obtained during the manufacture of ceddar cheese was. inhibitory to the one strain of L. casei tested. Thus, the production of an inhibitory substance by starter organisms may delay growth of lactobacilli in cheese during ripening. It also may exert a selective action that favors the predominance of less susceptible strains of lactic rods in the flora that develops.