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Food polyphenols are able to selectively modify the growth of susceptible micro-organisms. Wine is a good source of polyphenols and thus, the moderate consumption of this beverage can lead to the modulation of both oral and gut microbiota. This review aims to bring together the knowledge acquired concerning the potential effects of wine polyphenols on human microbiota, as well as taking into account the ability of bacteria to metabolize these compounds. Red wine phenolic composition, characterized by the occurrence of flavan-3-ols, flavonols, anthocyanins, hydroxybenzoic and hydroxycinnamic acids, stilbenes and phenolic alcohols as the main phenolic compounds, will determine the microbiota-modulating effects of wine consumption. Moreover, although the same bacterial genera can be found in oral and gut ecosystems, their relative amount is different, which can influence the metabolic transformations of wine polyphenols. Taking all this into account, the potential implications of these studies on human microbiota are finally discussed together with perspective and future research trends in this field. [Copyright &y& Elsevier]

Abstract: The diversity of the cheese microbiota contributes greatly to the complexity of the cheese-ripening process, crucially important for developing the unique sensory characteristics of each traditional cheese variety. Interactions between microorganisms, e.g. microbial co-operation and antagonistic effects, markedly impact on the survival, growth and activity of microorganisms in cheese. Bacteriocins are antimicrobials that are produced by lactic acid bacteria (LAB) and enable them to dominate the cheese ecosystem. Recently, there has been interest in the possible use of bacteriocins to promote the lysis of LAB and hence contribute to cheese proteolysis and flavour development. This review examines some of the strategies proposed for controlling bacteria in the cheese ecosystem as a means of ensuring high-quality production standards. It focuses on approaches such as the selection of adjuncts, especially facultatively heterofermentative lactobacilli, the selection of new wild strains of LAB and strategies based on microbial co-operation and microbial antagonism. [Copyright &y& Elsevier]

Caseinomacropeptide (CMP), isolated from cow’s or combined ewe’s and goat’s sweet cheese whey, and whey protein concentrate (WPC), enhanced growth of Bifidobacterium lactis in milk. Supplementation of milk at 2% CMP increased counts of B. lactis by 1.5 log cycles after 24 h incubation at 37 °C when compared with unsupplemented milk, showing no differences between the two CMPs. The highest bacterial growth (9.1 log cfu ml−1) was obtained when milk was supplemented with 2% WPC. The growth-promoting activity shown by WPC could be due to its CMP and whey protein content. CMP and WPC could be utilised to complement milk in order to increase counts of bifidobacteria in probiotic fermented milks. [Copyright &y& Elsevier]

Abstract: Cheese microbiota and their enzymatic conversion of l-methionine to volatile sulphur compounds (VSCs) play an important role in aroma formation during cheese ripening. Here, lactic acid bacteria (LAB) strains isolated from raw goats'' milk cheeses were screened for the major enzymes critical to the formation of VSCs from l-methionine. A large natural biodiversity in enzyme capabilities and high inter- and intra-species variability was found among the LAB isolates investigated. From those isolates tested, lactococci displayed higher C–S lyase specificities towards the sulphur-containing compounds examined than did Lactobacillus and Leuconostoc, in some cases generating higher levels of VSCs than B. linens, known to be an efficient producer of methanethiol (MTL) and related VSCs. Moreover, these differences in C–S lyase activities (determined spectrophotometrically by measuring the formation of free thiol groups) were shown to correspond with the enzymatic potential of the isolates as determined by visualization of enzymatic activities. This technique could therefore prove valuable for the detection and preliminary characterization of C–S lyase activities among LAB isolates. Lactococci were also found to possess higher aminotransferase activities than lactobacilli and leuconostocs, while glutamate dehydrogenase activities were observed to be highest among Leuconostoc and Lactobacillus spp. Meanwhile, α-keto acid decarboxylase activities were highly variable and were measurable in only a limited number of isolates, mainly lactobacilli. From these data, combining indigenous isolates showing high VSCs-producing capabilities with those that facilitate the completion of the metabolic pathway responsible for degrading l-methionine into volatile compounds may provide an efficient approach to enhance cheese aroma development. [Copyright &y& Elsevier]

Abstract: This study describes selective plating methodologies for enumeration of mixed cultures of Streptococcus thermophilus, Lactobacillus delbrueckii subsp. bulgaricus, L. acidophilus, L. paracasei subsp. paracasei and Bifidobacterium lactis in fermented milk based on selective antibiotic-free media. Enumeration of S. thermophilus was performed using M17-lactose. MRS-fructose was suitable for enumeration of L. bulgaricus and MRS-maltose for differentiation between L. acidophilus and L. paracasei. The selective enumeration of B. lactis was obtained using MRS-raffinose containing 0.05% LiCl. The bacterial counts obtained using selective methods were equivalent to those under optimum culture conditions at a probability level of 95%. Performance of the methods was verified in fermented milk products where identification of the enumerated species was confirmed by species-specific polymerase chain reaction. This study shows that combination of species-specific polymerase chain reaction (PCR) and denaturing gradient gel electrophoresis (DGGE) analysis has great detection and identification potential for verification of accurate species labelling in fermented milk without prior isolation of the bacteria. [Copyright &y& Elsevier]

Abstract: A hygienized rennet paste (HRP) and a defined strain starter culture, including Lactobacillus casei subsp. casei IFPL as adjunct, were considered for manufacturing Majorero cheese, a Spanish traditional variety made from goat milk. Influence of both factors on physicochemical characteristics, proteolysis, rheological and sensory properties, was evaluated throughout the ripening. Cheeses produced either industrially (IL) or in artisanal manner (AL) were compared with the experimental lot (EL), which included HRP and IFPL starter in its manufacture. Results showed a low level of primary proteolysis, expressed by a low content of non-casein nitrogen (NCN), in experimental cheeses. Despite the slightly poor texture (hard and crumbly) related to the high TS and salt contents, a good general acceptability was attained for EL, with the best scores for aroma and flavour intensities achieved at 30 ripening days. In fact, the sensory panel detected the “piquant” flavour (typical of the artisanal cheese variety) in EL after 15 days of ripening. [Copyright &y& Elsevier]

Abstract: Several wild lactococcal strains were tested for their ability to produce aroma compounds during growth in milk. Strains were incubated alone and in combination with Lactococcus lactis IFPL730, which is characterized by showing α-keto acid decarboxylase activity. Volatile compounds from incubated milks were analyzed by means of solid-phase microextraction (SPME) and evaluated by gas chromatography–mass spectrometry (GC–MS). Incubated milks were also sniffed for sensory analysis to describe aroma attributes. The combination of L. lactis IFPL326 that showed the highest branched chain aminotransferase activity with IFPL730 contributed to the highest formation of leucine-derived volatile compounds, such as 3-methylbutanal, 3-methyl-1-butanol and 2-hydroxy-4-methyl pentanoic acid methyl ester. In addition, the milk incubated with this combination of strains was awarded, by the test panellists, the highest scores for “ripened cheese” attribute and aroma intensity. The results indicate that combination of L. lactis strains harbouring complementary catabolic routes can contribute to improved cheese aroma formation, the combined cultures with L. lactis IFPL730 resulting in higher volatile compound formation than isolate strains. [Copyright &y& Elsevier]

Abstract: A total of 156 lactic acid bacteria isolates belonging to the genera Lactococcus, Lactobacillus and Leuconostoc were analysed for the amino acid converting enzymes aminotransferases, glutamate dehydrogenase, and α-ketoisovalerate decarboxylase. All isolates showed aminotransferase activity towards phenylalanine (substrate for the aromatic aminotransferase AraT) and isoleucine (substrate for the branched-chain aminotransferase BcaT). Although there was a high variability inter- and intra-species, the lactococcal strains showed the highest values for both aminotransferase activities. Moreover, α-ketoisovalerate decarboxylase (Kivd) activity was only found in lactococcal isolates, although at low relative numbers (16%). On the other hand, glutamate dehydrogenase (Gdh) activity values were highest in facultative heterofermentative lactobacilli (FHL) and the activity was found at high relative numbers (50%) in leuconostocs. Results showed a high variability in amino acid convertase activities within the wild LAB isolates assayed, therefore the utilisation in the dairy industry of new strains with high flavour-forming abilities could be a powerful tool to enhance cheese aroma development. [Copyright &y& Elsevier]

A set-type fermented milk manufactured from goat''s milk was developed. Optimal curd tension was achieved by supplementation of milk with skim milk powder and whey protein concentrate (WPC). Milk was fermented employing a commercial probiotic starter culture (ABT-2), which contained Streptococcus thermophilus ST-20Y, Lactobacillus acidophilus LA-5, and Bifidobacterium BB-12. Supplementation of milk with 3% WPC reduced fermentation time by 2 h due to the increase in viable counts of S. thermophilus and Bifidobacterium by 0.3 and 0.7 log units, respectively. Addition of WPC increased the protein content (1%) as well as potassium and magnesium content (0.3 and 0.02 g kg−1, respectively). Increase of the protein content led to an increase in the apparent viscosity and gel firmness of the product, and at the same time whey syneresis was reduced. As a consequence, the product received a high score for appearance, taste, aroma, texture and overall acceptance. [Copyright &y& Elsevier]