Study of volatile compounds profiles in milk matrices using Enterococcus faecalis EstA and Rhizomucor miehei lipase.

The use of esterase/lipase enzymes of different origins in food industry is a widely employed strategy to enhance the formation of characteristic aromatic compounds derived from fat and diversify flavour. In the present work, we studied EstA enzyme of Enterococcus faecalis and a high purity Rhizomucor miehei lipase (Palatase). EstA was obtained recombinantly in Escherichia coli BL21 (DE3), and optimum esterase activity was detected at pH 6.

Effect of the incorporation of β-galactosidase in the GOS production during manufacture of soft cheese.

Galactooligosaccharides (GOS) are non-digestible oligosaccharides with recognized prebiotic role. The present study aims to evaluate a β-galactosidase from K. lactis during soft cheese making and to analyse the impact on carbohydrates metabolism, proteolysis, and volatile compounds production, physicochemical and microbiological characteristics of the product.

Evaluation of autochthonous cultures to improve the cheese flavor: A case study in hard cheese model.

The characterization of autochthonous cultures based on their contribution to cheese flavor is an additional selection criterion for their use in cheese making. The objective of the present work was to assess the ability of three strains of mesophilic lactobacilli: 72 (Lc72), 90 (Lp90), and 91 (Lp91), one strain of thermophilic lactobacillus: 209 (Lh209), and the thermophilic-mesophilic combinations, to grow and produce aroma compounds in a hard cheese model. Microbiological counts, pH, and the profiles of carbohydrates, organic acids, and volatile compounds were analyzed during incubation for 14 days at 37 ℃.

Influence of the culture preparation and the addition of an adjunct culture on the ripening profiles of hard cheese.

The aim of this work was to evaluate the impact of two factors on the ripening profiles of hard cooked cheeses: (F1) the growth medium for the primary and adjunct cultures, constituted by autochthonous strains: Lactobacillus helveticus 209 (Lh209) and Lactobacillus paracasei 90 (Lp90), respectively, and (F2) the addition of L. paracasei Lp90 as adjunct culture. Four types of cheeses were made: W and M cheeses in which only Lh209 was added after its growth in whey and MRS, respectively; Wa and Ma cheeses in which both strains (Lh209 and Lp90) were added after their growth in whey and MRS, respectively.

Response surface methodology as a tool for modelling galacto-oligosaccharide production.

The experiments reported in this research paper describe the effects of β-galactosidase enzyme dose and cheese whey amount, on the maximum concentration and yield of galacto-oligosaccahride (GOS) and reaction time. The experimental plan was based on central composite rotational design (CCRD) and modelled by response surface methodology (RSM). The results indicate that the proposed mathematical models could adequately describe the concentration and yield of GOS and the reaction time within the limits of the factors that are being investigated.

Characterization of volatile compounds produced by Lactobacillus helveticus strains in a hard cheese model.

Starter cultures of Lactobacillus helveticus used in hard cooked cheeses play an important role in flavor development. In this work, we studied the capacity of three strains of L. helveticus, two autochthonous (Lh138 and Lh209) and one commercial (LhB02), to grow and to produce volatile compounds in a hard cheese extract.

Cheese milk low homogenization enhanced early lipolysis and volatiles compounds production in hard cooked cheeses.

Homogenization applied to cheese milk has shown to increase lipolysis but its use is not spread as it can induce detrimental effects. The aim of this work was to assess the effect of low-pressure homogenization of the cream followed by pre-incubation of cheese milk on the composition, ripening index, lipolysis and volatile profiles of hard cooked cheeses. For that, control and experimental miniature Reggianito cheeses were made and analyzed during ripening (3, 45 and 90days).

Influence of lactose hydrolysis on galacto-oligosaccharides, lactose, volatile profile and physicochemical parameters of different yogurt varieties.

Background: Different types of reduced-lactose yogurt, obtained by lactose hydrolysis using β-galactosidase enzyme, are commercially available. The breakdown of lactose modifies the carbohydrate profile, including the production of prebiotic galacto-oligosaccharides (GOS), which could affect the survival and activity of starter and probiotic cultures and the parameters of yogurt quality. The extension of these changes is dependent on the yogurt matrix composition.

Influence of autochthonous adjunct cultures on ripening parameters of Argentinean goat's milk cheeses.

Background: Argentinean semi-hard goat's cheeses manufactured with and without the addition of autochthonous adjunct cultures of Lactobacillus plantarum ETC17, Lactobacillus rhamnosus ETC14 and Enterococcus faecium ETC3 were analysed to evaluate the effect of these strains on ripening parameters.

Results: Gross composition was similar among cheeses. Microbiological analysis indicated that lactic acid bacteria added to cheeses reached high levels.

Composition and volatile profiles of commercial Argentinean blue cheeses.

Background: A first approach was made to acquire knowledge of the global composition, proteolysis, lipolysis and volatile profile of Argentinean blue cheeses. A total of 20 samples belonging to six leading commercial brands were analysed. A comparison of the results with bibliographical data on other blue cheeses was performed and the variability among and within dairy plants was also evaluated.