The antimicrobial activity of heat-denatured and hydrolyzed hen egg white lysozyme against oenological lactic acid and acetic acid bacteria was investigated. The lysozyme was denatured by heating, ...and native and heat-denatured lysozymes were hydrolyzed by pepsin. The lytic activity against Micrococcus lysodeikticus of heat-denatured lysozyme decreased with the temperature of the heat treatment, whereas the hydrolyzed lysozyme had no enzymatic activity. Heat-denatured and hydrolyzed lysozyme preparations showed antimicrobial activity against acetic acid bacteria. Lysozyme heated at 90 degrees C exerted potent activity against Acetobacter aceti CIAL-106 and Gluconobacter oxydans CIAL-107 with concentrations required to obtain 50% inhibition of growth (IC50) of 0.089 and 0.013 mg/ml, respectively. This preparation also demonstrated activity against Lactobacillus casei CIAL-52 and Oenococcus oeni CIAL-91 (IC50, 1.37 and 0.45 mg/ml, respectively). The two hydrolysates from native and heat-denatured lysozyme were active against O. oeni CIAL-96 (IC50, 2.77 and 0.3 mg/ml, respectively). The results obtained suggest that thermal and enzymatic treatments increase the antibacterial spectrum of hen egg white lysozyme in relation to oenological microorganisms.
The accumulation of microplastics (MPs) in the environment as well as their presence in foods and humans highlight the urgent need for studies on the effects of these particles on humans. Polylactic ...acid (PLA) is the most widely used bioplastic in the food industry and medical field. Despite its biodegradability, biocompatibility, and "Generally Recognized As Safe" (GRAS) status, recent animal model studies have shown that PLA MPs can alter the intestinal microbiota; however, to date, no studies have been reported on the possible gut and health consequences of its intake by humans. This work simulates the ingestion of a realistic daily amount of PLA MPs and their pass through the gastrointestinal tract by combining the INFOGEST method and the gastrointestinal simgi® model to evaluate possible effects on the human colonic microbiota composition (16S rRNA gene sequencing analysis) and metabolic functionality (lactic acid and short-chain fatty acids (SCFA) production). Although PLA MPs did not clearly alter the microbial community homeostasis, increased Bifidobacterium levels tended to increase in presence of millimetric PLA particles. Furthermore, shifts detected at the functional level suggest an alteration of microbial metabolism, and a possible biotransformation of PLA by the human microbial colonic community. Raman spectroscopy and field emission scanning electron microscopy (FESEM) characterization revealed morphological changes on the PLA MPs after the gastric phase of the digestion, and the adhesion of organic matter as well as a microbial biofilm, with surface biodegradation, after the intestinal and colonic phases. With this evidence and the emerging use of bioplastics, understanding their impact on humans and potential biodegradation through gastrointestinal digestion and the human microbiota merits critical investigation.
Aims: To investigate the effect of seven wine phenolic compounds and six oenological phenolic extracts on the growth of pathogenic bacteria associated with respiratory diseases (Pseudomonas ...aeruginosa, Staphylococcus aureus, Moraxella catarrhalis, Enterococcus faecalis, Streptococcus sp Group F, Streptococcus agalactiae and Streptococcus pneumoniae). Methods and Results: Antimicrobial activity was determined using a microdilution method and quantified as IC50. Mor. catarrhalis was the most susceptible specie to phenolic compounds and extracts. Gallic acid and ethyl gallate were the compounds that showed the greatest antimicrobial activity. Regarding phenolic extracts, GSE (grape seed extract) and GSE‐O (oligomeric‐rich fraction from GSE) were the ones that displayed the strongest antimicrobial effects. Conclusions: Results highlight the antimicrobial properties of wine phenolic compounds and oenological extracts against potential respiratory pathogens. The antimicrobial activity of wine phenolic compounds was influenced by the type of phenolic compounds. Gram‐negative bacteria were more susceptible than Gram‐positive bacteria to the action of phenolic compounds and extracts; however, the effect was species‐dependent. Significance and Impact of Study: The ability to inhibit the growth of respiratory pathogenic bacteria as shown by several wine phenolic compounds and oenological extracts warrants further investigations to explore the use of grape and wine preparations in oral hygiene.
Changes in biogenic amines (histamine, methylamine, ethylamine, tyramine, phenylethylamine, putrescine, and cadaverine) were monitored during the industrial manufacture of 55 batches of red wine. The ...origin of these amines in relation to must, alcoholic fermentation, malolactic fermentation, sulfur dioxide addition, and wine aging and the interactions between amines and their corresponding amino acids and pH were statistically evaluated in samples from the same batches throughout the elaboration process. Some amines can be produced in the grape or the musts (e.g., putrescine, cadaverine, and phenylethylamine) or can be formed by yeast during alcoholic fermentation (e.g., ethylamine and phenylethylamine), although quantitatively only very low concentrations are reached in these stages (less than 3 mg/liter). Malolactic fermentation was the main mechanism of biogenic amine formation, especially of histamine, tyramine, and putrescine. During this stage, the increase in these amines was accompanied by a significant decline in their amino acid precursors. Significant correlations between biogenic amine formation and the disappearance of their corresponding amino acids were observed, which clearly supports the hypothesis that malolactic bacteria are responsible for accumulation of these amines in wines. No increase in the concentration of biogenic amines was observed after SO2 addition and during wine aging, indicating that sulfur dioxide prevents amine formation in subsequent stages.
Red wine amino acids and volatile compounds were analyzed before and after malolactic fermentation carried out by four different starter cultures of the species Oenococcus oeni and Lactobacillus ...plantarum. The purpose of this study was to determine whether differences can be attributed to the lactic acid bacteria strain used in this important step of the wine-making process. The malolactic cultures selected for this study were indigenous wine lactic acid bacteria strains. The data were evaluated using different multivariate analysis techniques. Results showed different malolactic behaviors for O. oeni and L. plantarum and significant metabolic differences between both species. A degree of diversity was found within each lactic acid bacteria group, since wines presented specific characteristics depending on the lactic acid bacteria strain used. In all cases, malolactic fermentation seemed to modify the amino acid and volatile composition of the wine. Keywords: Oenococcus oeni; Lactobacillus plantarum; wine; malolactic fermentation; amino acids; volatile compounds
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.
The potential to produce the biogenic amines tyramine, histamine and putrescine, was investigated for lactic acid bacteria (LAB) of various origin, including commercial malolactic starter cultures, ...type strains and 78 strains isolated from Spanish grape must and wine. The presence of biogenic amines in a decarboxylase synthetic broth was determined by reverse-phase high performance liquid chromatography (RP-HPLC). Tyramine was the main amine formed by the LAB strains investigated.
Leuconostoc strains were the most intensive tyramine formers. No potential to form biogenic amines was observed in
Oenococcus oeni strains. Two strains of
Latobacillus buchneri were associated with putrescine formation. None of the lactic acid bacteria produced histamine. According to these in vitro results, the commercial starter bacteria analyzed did not produce histamine, tyramine and putrescine.
The colonic microbiota plays an important role in the bioavailibility of dietary polyphenols. This work has evaluated the impact on the gut microbiota of long-term feeding with both a red wine ...polyphenolic extract and the flavan-3-ol metabolizer strain Lactobacillus plantarum IFPL935. The study was conducted in the dynamic Simulator of the Human Intestinal Microbial Ecosystem (SHIME). The feeding of the gut microbiota model with red wine polyphenols caused an initial decrease in the counts of total bacteria in the ascending colon (AC), with Bacteroides, Clostridium coccoides/Eubacterium rectale and Bifidobacterium being the most affected bacterial groups. The bacterial counts recovered to initial numbers faster than the overall microbial fermentation and proteolysis, which seemed to be longer affected by polyphenols. Addition of L. plantarum IFPL935 helped to promptly recover total counts, Lactobacillus and Enterobacteriaceae and led to an increase in lactic acid formation in the AC vessel at the start of the polyphenol treatment as well as butyric acid in the transverse (TC) and descending (DC) vessels after 5 days. Moreover, L. plantarum IFPL935 favoured the conversion in the DC vessel of monomeric flavan-3-ols and their intermediate metabolites into phenylpropionic acids and in particular 3-(3′-hydroxyphenyl)propionic acid. The results open the possibilities of using L. plantarum IFPL935 as a food ingredient for helping individuals showing a low polyphenol-fermenting metabotype to increase their colonic microbial capacities of metabolizing dietary polyphenols.
BACKGROUND AND AIMS: The aim of this study was to evaluate the influence of the composition of the non‐volatile wine matrix on the temporal aroma release profile using an artificial mouth device ...coupled online to a proton transfer reaction – time‐of–flight – mass spectrometer (PTR‐ToF‐MS). METHODS AND RESULTS: Five wines, white, sparkling, young red, aged red and sweet wines, were lyophilised, de‐aromatised and reconstituted to equal ethanol concentration and spiked with eight target aroma compounds and human saliva. Aroma release was monitored in real time by using an artificial mouth coupled to a PTR‐ToF‐MS. Matrix composition had a considerable influence on the temporal aroma release parameters maximum intensity: Iₘₐₓ and area under the curve (AUC) in the first 30 s of aroma monitoring. In general, red wines showed the highest aroma release, sweet wines the lowest. CONCLUSIONS: The physicochemical characteristics of the aroma compounds and the wine matrix composition play a significant role on the temporal aroma release from wines. The formation of complexes between wine polyphenols and saliva glycoproteins appears to change wine polarity favoring the release of hydrophobic aroma compounds. SIGNIFICANCE OF THE STUDY: This study has highlighted the importance of considering the wine non‐volatile composition as a necessary parameter to understand wine aroma perception during the dynamics of wine intake.
BACKGROUND AND AIMS: Inactive dry yeast (IDY) preparations are widely used in the winemaking industry. Among them, glutathione (GSH)‐enriched IDY (g‐IDY) preparations are claimed to preserve the ...aroma and colour of white wines due to their antioxidant properties. It remains uncertain, however, if alcoholic fermentation (AF) influences the fate of the GSH released by IDYs and the impact of these preparations on the oxidation status of the wine, which constitutes the aim of this study. METHODS AND RESULTS: The evolution of the GSH concentration of white musts treated with two types of IDYs (a glutathione‐enriched IDY, g‐IDY, and a fermentative nutrient n‐IDY without GSH) and of a control must was determined during AF. In addition, the oxidation status of the musts and the formation of grape reaction product (GRP) derivatives were also monitored. The addition of g‐IDYs had little effect on the concentration of reduced GSH in the wines at the end of fermentation. The treatment of musts with IDY preparations, however, reduced the formation of derivatives of GRP and produced more reductive conditions during AF compared with that of control samples. CONCLUSIONS: These results indicate that GSH released by IDYs is not available at the end of AF, but other yeast components from these preparations could be involved in the greater antioxidant status of musts treated with IDYs. SIGNIFICANCE OF THE STUDY: This study helps to understand the impact of IDY preparations during winemaking, which will assist the optimisation of their formulation for specific wine applications.
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