Search results for "ACID BACTERIA"
showing 10 items of 165 documents
Maintenance of Wine-Associated Microorganisms
2008
A great variety of microorganisms growing on grapes, in must, or in wine have been isolated, which also have an influence on wine quality. They belong to acidtolerant microorganisms such as lactic acid bacteria, acetic acid bacteria, and yeasts. On grapes also molds can be found. The most important species for conversion of must into wine are the yeast Saccharomyces cerevisiae and the lactic acid bacterium Oenococcus oeni, which perform alcoholic and malolactic fermentation, respectively. Both species are used as starter cultures. A variety of techniques and media are available for the enrichment, culture, and preservation of these microorganisms. For selected species culture and preservati…
Microbiological and chemical monitoring of Marsala base wine obtained by spontaneous fermentation during large-scale production
2014
The present work was undertaken to evaluate the effect of natural wine making on the microbial and chemical composition of Marsala base wine. To this purpose, a large-scale vinification process of Grillo grape cultivar was monitored from the grape harvest to the final product. Total yeasts (TY) showed a rapid increase after must pressings and reached values that were almost identical to those registered during conventional wine makings. Lactic acid bacteria (LAB) were registered at the highest levels simultaneous to those of yeast growth at the beginning of the process. Saccharomyces cerevisiae was the species found at the highest concentrations in all samples analysed. Several strains (n =…
Activation of wooden vats with selected lactic acid bacteria for the year-round production of traditional Vastedda-like cheese
2014
Vastedda is a pasta filata cheese made from raw ewes’ milk without the addition of starter cultures. Cheese production is carried out in wooden vats characterized by microbial biofilms hosting lactic acid bacteria (LAB) responsible for the acidification of the curds. Vastedda cheese was traditionally produced during the summer season, but it is currently produced throughout the year. In order to minimize production variability, several LAB were isolated from Vastedda PDO cheeses, characterized for their technological potential (Gaglio et al., 2014a) and selected to obtain the best strain combination for the production (Gaglio et al., 2014b). In this study, the multiple strain culture compos…
Study of biogenic amines metabolism in wine lactic acid bacteria
2011
Biogenic amines are indesirable compounds found in fermented products like wine. Lactic acid bacteria from wine, including Oenococcus oeni, the main actor of malolactic fermentation, are able to produce these molecules from nitrogenous precursors. In order to limited biogenic amines accumulation, it is necessary to understand the role of this production by strains responsible for the synthesis of these metabolites in food. That is why the European BiamFood project was put in place. Along my thesis, molecular tools were developed in order to mutate O. oeni genes (encoding decarboxylases), and to express genes of interest. Genetic clusters hdc from L. higardii and odc from O. oeni, responsibl…
Screening of lactic acid bacteria for their use as aromatic starters during fermentation of vegetables
2020
Lactic acid bacteria (LAB) have good growth capacities on various food matrices and produce very diverse enzymatic activities which are notably capable of positively modifying the organoleptic properties of fermented foods. Therefore, the selection of the LAB starters possessing good metabolic abilities and interesting enzymatic activities towards the plant matrix could improve the aroma profiles of fermented foods. The main objective of this study was to enhance the aroma profiles of fermented tomatoes by using the biotechnological pathway. To achieve this, firstly, 200 LAB isolated from Cambodian and Vietnamese fermented foods were screened for their β-glucosidase activity and duplicate i…
Effect of oxidoreduction potential on aroma biosynthesis by lactic acid bacteria in nonfat yogurt
2011
; The aim of this study was to investigate the effect of oxidoreduction potential (Eh) on the biosynthesis of aroma compounds by lactic acid bacteria in non-fat yogurt. The study was done with yogurts fermented by Lactobacillus bulgaricus and Streptococcus thermophilus. The Eh was modified by the application of different gaseous conditions (air, nitrogen, and nitrogen/hydrogen). Acetaldehyde, dimethyl sulfide, diacetyl, and pentane-2,3-dione, as the major endogenous odorant compounds of yogurt, were chosen as tracers for the biosynthesis of aroma compounds by lactic acid bacteria. Oxidative conditions favored the production of acetaldehyde, dimethyl sulfide, and diketones (diacetyl and pen…
Discovering lactic acid bacteria by genomics
2002
International audience; This review summarizes a collection of lactic acid bacteria that are now undergoing genomic sequencing and analysis. Summaries are presented on twenty different species, with each overview discussing the organisms fundamental and practical significance, environmental habitat, and its role in fermentation, bioprocessing, or probiotics. For those projects where genome sequence data were available by March 2002, summaries include a listing of key statistics and interesting genomic features. These efforts will revolutionize our molecular view of Gram-positive bacteria, as up to 15 genomes from the low GC content lactic acid bacteria are expected to be available in the pu…
Bioaccessibility Study of Aflatoxin B1 and Ochratoxin A in Bread Enriched with Fermented Milk Whey and/or Pumpkin
2021
The presence of mycotoxins in cereals and cereal products remains a significant issue. The use of natural ingredients such as pumpkin and whey, which contain bioactive compounds, could be a strategy to reduce the use of conventional chemical preservatives. The aim of the present work was to study the bioaccessibility of aflatoxin B1 (AFB1) and ochratoxin (OTA) in bread, as well as to evaluate the effect of milk whey (with and without lactic acid bacteria fermentation) and pumpkin on reducing mycotoxins bioaccessibility. Different bread typologies were prepared and subjected to an in vitro digestion model. Gastric and intestinal extracts were analyzed by HPLC–MS/qTOF and mycotoxins bio…
Comparative analysis of production and purification of homo- and hetero-polysaccharides produced by lactic acid bacteria
2013
2 figuras, 2 tablas
Evaluation of yogurt and various beverages as carriers of lactic acid bacteria producing 2-branched (1,3)-β-D-glucan
2011
8 páginas, 2 figuras, 2 tablas -- PAGS nros. 3271-3278