Phylogenetic profile of gut microbiota in healthy adults after moderate intake of red wine

SCOPE

There is growing interest in understanding how human colonic microbiota can be modified by dietary habits. We examined the influence of moderate red wine intake on the colonic microbiota of 15 healthy volunteers, related to the high concentration of polyphenols present in this beverage. The volunteers were classified into high, moderate, and low polyphenol metabolizers (metabotypes) due to their ability to metabolize polyphenols and the results were compared with that of five control (no wine intake) subjects.

METHODS AND RESULTS

We analyzed the composition, diversity, and dynamics of their fecal microbiota before and after 1 month of wine consumption. The 16S rDNA sequencing allowed detection of 2324 phylotypes, of which only 30 were found over the 0.5% of mean relative frequency, representing 84.6% of the total taxonomical assignments. The samples clustered more strongly by individuals than by wine intake or metabotypes, however an increase in diversity, after the wine intake, was observed.

CONCLUSION

The results of this study suggest an increase in the global fecal microbial diversity associated to the consumption of red wine, confirm the high variability of the microbiota from different individuals, and show the stability of their singular microbiota composition to small and short-term dietary changes.

Profiling of Phenolic Metabolites in Feces from Menopausal Women after Long-Term Isoflavone Supplementation

Phenolic compounds were screened by UPLC-ESI-MS/MS in the feces of 15 menopausal women before and after long-term isoflavone treatment. In total, 44 compounds were detected. Large intertreatment, interindividual, and intersample variations were observed in terms of the number of compounds and their concentration. Four compounds, the aglycones daidzein and genistein and the daidzein derivatives dihydrodaidzein and O-desmethylangolensin, were associated with isoflavone metabolism; these were identified only after the isoflavone treatment. In addition, 4-ethylcatechol, 3-hydroxyphenylacetic acid, and 3-phenylpropionic acid differed significantly in pre- and postintervention samples, whereas the concentration of 4-hydroxy-5-phenylvaleric acid showed a trend toward increasing over the treatment. The phenolic profiles of equol-producing and -non-producing groups were similar, with the exceptions of 3-hydroxyphenylacetic acid and 3-phenylpropionic acid, which showed higher concentrations in equol-non-producing women. These findings may help to trace isoflavone-derived metabolites in feces during isoflavone interventions and to design new studies to address their biological effects.

Ability of human oral microbiota to produce wine odorant aglycones from odourless grape glycosidic aroma precursors

Grape aroma precursors are odourless glycosides that represent a natural reservoir of potential active odorant molecules in wines. Since the first step of wine consumption starts in the oral cavity, the processing of these compounds in the mouth could be an important factor in influencing aroma perception. Therefore, the objective of this work has been to evaluate the ability of human oral microbiota to produce wine odorant aglycones from odourless grape glycosidic aroma precursors previously isolated from white grapes. To do so, two methodological approaches involving the use of typical oral bacteria or the whole oral microbiota isolated from human saliva were followed. Odorant aglycones released in the culture mediums were isolated and analysed by HS-SPME-GC/MS. Results showed the ability of oral bacteria to hydrolyse grape aroma precursors, releasing different types of odorant molecules (terpenes, benzenic compounds and lipid derivatives). The hydrolytic activity seemed to be bacteria-dependent and was subject to large inter-individual variability.

Studies on Modulation of Gut Microbiota by Wine Polyphenols: From Isolated Cultures to Omic Approaches

Moderate consumption of wine seems to produce positive health effects derived from the occurrence of bioactive polyphenols. The gut microbiota is involved in the metabolism of phenolic compounds, and these compounds and/or their metabolites may modulate gut microbiota through the stimulation of the growth of beneficial bacteria and the inhibition of pathogenic bacteria. The characterization of bacterial metabolites derived from polyphenols is essential in order to understand their effects, including microbial modulation, and therefore to associate dietary intake with particular health effects. This review aims to summarize the current information about the two-way "wine polyphenols-gut microbiota" interaction, from a perspective based on the experimental and analytical designs used. The availability of advanced methods for monitoring bacterial communities, along with the combination of in vitro and in vivo models, could help to assess the metabolism of polyphenols in the human body and to monitor total bacterial communities, and, therefore, to elucidate the implications of diet on the modulation of microbiota for delivering health benefits.

Faecal metabolomic fingerprint after moderate consumption of red wine by healthy subjects

Faecal metabolome contains information on the metabolites found in the intestine, from which knowledge about the metabolic function of the gut microbiota can be obtained. Changes in the metabolomic profile of faeces reflect, among others, changes in the composition and activity of the intestinal microorganisms. In an effort to improve our understanding of the biological effects that phenolic compounds (including red wine polyphenols) exert at the gut level, in this foodomic study we have undertaken a metabolome characterization of human faeces after moderate consumption of red wine by healthy subjects for 4 weeks. Namely, a nontargeted metabolomic approach based on the use of UHPLC-TOF MS was developed to achieve the maximum metabolite information on 82 human faecal samples. After data processing and statistical analysis, 37 metabolites were related to wine intake, from which 20 could be tentatively or completely identified, including the following: (A) wine compounds, (B) microbial-derived metabolites of wine polyphenols, and (C) endogenous metabolites and/or others derived from other nutrient pathways. After wine consumption, faecal metabolome was fortified in flavan-3-ols metabolites. Also, of relevance was the down regulation of xanthine and bilirubin-derived metabolites such as urobilinogen and stercobilin after moderate wine consumption. As far as we know, this is the first study of the faecal metabolome after wine intake.

Moderate consumption of red wine can modulate human intestinal inflammatory response

In this study, 24 immune markers were analyzed in feces from healthy volunteers (n = 34) before and after consumption of a red wine (12% ethanol, 1758 mg/L total polyphenols) for 4 weeks. Analysis of the data permitted the differentiation of a six-volunteer subgroup showing unusually high basal values of cytokines. For this subgroup, consumption of wine significantly (P < 0.05) reduced the content of 16 markers to usual values, especially noticeable for those cytokines that promote initial inflammation (TNF-α, IL-6, and IFN-γ). On the contrary, no significant differences in the concentration of any immune marker were observed after wine consumption for the rest of the volunteers. Additionally, significant and negative correlations among cytokines IFN-γ, IL-8, and IL-6 and the total fecal content of phenolic metabolites were found for the high-cytokines-values subgroup, before wine intake. This study shows, for the first time, that moderate consumption of red wine could modulate inflammatory intestinal response in vivo.

Antibacterial activity of hen egg white lysozyme modified by heat and enzymatic treatments against oenological lactic acid bacteria and acetic acid bacteria

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°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.

Understanding the role of saliva in aroma release from wine by using static and dynamic headspace conditions

The aim of this work was to determine the role of saliva in wine aroma release by using static and dynamic headspace conditions. In the latter conditions, two different sampling points (t = 0 and t = 10 min) corresponding with oral (25.5 °C) and postoral phases (36 °C) were monitored. Both methodologies were applied to reconstituted dearomatized white and red wines with different nonvolatile wine matrix compositions and a synthetic wine (without matrix effect). All of the wines had the same ethanol concentration and were spiked with a mixture of 45 aroma compounds covering a wide range of physicochemical characteristics at typical wine concentrations. Two types of saliva (human and artificial) or control samples (water) were added to the wines. The adequacy of the two headspace methodologies for the purposes of the study (repeatability, linear ranges, determination coefficients, etc.) was previously determined. After application of different chemometric analysis (ANOVA, LSD, PCA), results showed a significant effect of saliva on aroma release dependent on saliva type (differences between artificial and human) and on wine matrix using static headspace conditions. Red wines were more affected than white and synthetic wines by saliva, specifically human saliva, which provoked a reduction in aroma release for most of the assayed aroma compounds independent of their chemical structure. The application of dynamic headspace conditions using a saliva bioreactor at the two different sampling points (t = 0 and t = 10 min) showed a lesser but significant effect of saliva than matrix composition and a high influence of temperature (oral and postoral phases) on aroma release.

Red wine and oenological extracts display antimicrobial effects in an oral bacteria biofilm model

The antimicrobial effects of red wine and its inherent components on oral microbiota were studied by using a 5-species biofilm model of the supragingival plaque that includes Actinomyces oris, Fusobacterium nucleatum, Streptococcus oralis, Streptococcus mutans and Veillonella dispar. Microbiological analysis (CFU counting and confocal laser scanning microscopy) of the biofilms after the application of red wine, dealcoholized red wine, and red wine extract solutions spiked or not with grape seed and inactive dry yeast extracts showed that the solutions spiked with seed extract were effective against F. nucleatum, S. oralis and A. oris. Also, red wine and dealcoholized wine had an antimicrobial effect against F. nucleatum and S. oralis. Additional experiments showed almost complete and early degradation of flavan-3-ol precursors [(+)-catechin and procyanidin B2] when incubating biofilms with the red wine extract. To our knowledge, this is the first study of antimicrobial properties of wine in an oral biofilm model.

Impact of glutathione-enriched inactive dry yeast preparations on the stability of terpenes during model wine aging

The impact of the addition of glutathione-enriched Inactive dry yeast preparations (g-IDYs) on the stability of some typical wine terpenes (linalool, α-terpineol, β-citronellol, and nerol) stored under accelerated oxidative conditions was evaluated in model wines. Additionally, the effects of a second type of IDY preparation with a different claim (fermentative nutrient) and the sole addition of commercial glutathione into the model wines were also assessed. Model wines were spiked with the low molecular weight fraction (<3 kDa permeate) isolated from the IDYs, avoiding the interaction of aroma compounds with other yeast components. An exhaustive chemical characterization of both IDY permeates was carried out by using targeted and nontargeted metabolomics approaches using CE-MS and FT-ICR-MS analytical platforms. The findings suggest that the addition of <3 kDa permeate isolated from any of the IDYs employed decreases the loss of typical wine terpenes in model wines submitted to accelerated aging conditions. The g-IDY preparation did indeed release reduced GSH into the model wines, although this compound did not seem exclusively related to the protective effect on some aroma compounds determined in both model wines. The presence of other sulfur-containing compounds from yeast origin in g-IDY, and also the presence of small yeast peptides, such as methionine/tryptophan/tyrosine-containing tripeptide in both types of IDYs, seemed to be related to the antioxidant activity determined in the two permeates and to the minor loss of some terpenes in the model wines spiked with them.

Impact of the nonvolatile wine matrix composition on the in vivo aroma release from wines

The impact of the nonvolatile wine matrix composition on the retronasal aroma release of four volatile compounds added to different types of wines has been evaluated. For this purpose, a tailor-made retronasal aroma trapping device (RATD) was used to entrap the exhaled breath of six panelists previously trained in a specific consumption procedure. Five wines of different composition (white wine, sparkling white wine, young red wine, aged red wine, and a sweet wine) were evaluated. Prior to the evaluation, with the exception of the sweet wine, the wines were adjusted to the same ethanol content and aromatized with a mixture of four target volatile compounds. Aroma release data were submitted to multivariate statistical analysis in order to relate wine chemical composition and aroma release during wine drinking. Results showed interindividual differences and a clustering of panelists among lower and higher aroma releasers, which was in agreement to the differences in their breathing capacity. A significant influence of the matrix composition in the low aroma releasers group during wine consumption was observed. The consumption of red wines provoked a significantly higher aroma release than the consumption of white and sweet wines. From the chemical composition determined in the wine samples (pH, total acidity, total polyphenols, neutral polysaccharides, residual sugar, and nitrogenous compounds), the amount of total polyphenols was better correlated with the observed effect.

Profiling of microbial-derived phenolic metabolites in human feces after moderate red wine intake

A controlled and randomized trial study involving 41 healthy volunteers (33 intervention and 8 control subjects) was performed in order to establish changes in the microbial-derived phenolic metabolite profile of feces after moderate consumption of red wine (250 mL/day, 4 weeks). Out of the 35 phenolic metabolites identified, 10 compounds (mainly benzoic and 4-hydroxyvaleric acids) showed statistically significant increases (P < 0.05) after the wine intake. Also, the total phenolic metabolites content was significantly (P < 0.05) higher in the samples after the wine intake (625 ± 380 μg/g feces) in comparison to the samples before (358 ± 270 μg/g feces), and a tentative distribution of the volunteers into three groups could be established: <500, 500-1000, and >1000 μg/g feces. These results suggest that a different gut microbial capacity to metabolize wine polyphenols exists among the human population, as observed for polyphenols from other sources.

Assessment of the impact of the addition of antimicrobial plant extracts to wine: volatile and phenolic composition

BACKGROUND

Antimicrobial plant phenolic-rich extracts have been proposed as alternative to sulfites in the control of the malolactic fermentation (MLF) during winemaking. This addition may affect wine organoleptic properties. In this paper, we have investigated the changes in wine volatile and phenolic composition, after MLF, of a red wine treated with antimicrobial extracts from eucalyptus leaves and almond skins.

RESULTS

Although addition of both extracts led to statistically significant changes (P < 0.05) in the concentration of several esters, alcohols, C13 nor-isoprenoids and volatile phenols, only few of these volatile compounds showed values of odour activity > 1 aroma unit; that is to say, whose concentrations were higher than their corresponding odour thresholds. With regard to phenolic compounds, the addition of both extracts did not significantly modify the content of anthocyanins, which predicts minor changes in wine colour. However, the content of non-anthocyanin phenolics was significantly higher in the wines treated with antimicrobial extracts, especially for flavonols, being the dose-over-taste factor for these wines significantly higher. Finally, principal component analysis showed that wines were mainly differentiated on the basis of whether MLF was conducted or not, and its method of performance (inoculated/spontaneous).

CONCLUSION

Addition of antimicrobial extracts leads to some compositional changes in the wine, whose relevance needs to be addressed in future experiments, including wine sensorial analysis.

Comparative study of microbial-derived phenolic metabolites in human feces after intake of gin, red wine, and dealcoholized red wine

The analysis of microbial phenolic metabolites in fecal samples from in vivo studies is crucial to understanding the potential modulatory effects derived from polyphenol consumption and its overall health effects, particularly at the gut level. In this study, the composition of microbial phenolic metabolites in human feces collected after regular consumption of either red wine, dealcoholized red wine, or gin was analyzed by UPLC-ESI-MS/MS. Red wine interventions produce a change in the content of eight phenolic acids, which are probably derived from the catabolism of flavan-3-ols and anthocyanins, the main flavonoids in red wine. Moreover, alcohol seemed not to influence the formation of phenolic metabolites by the gut microbiota. A principal component analysis revealed large interindividual differences in the formation of microbial metabolites after each red wine polyphenol intervention, but not after the gin intervention, indicating differences in the gut microbial composition among subjects.

In vitro fermentation of grape seed flavan-3-ol fractions by human faecal microbiota: changes in microbial groups and phenolic metabolites

With the aim of investigating the potential of flavan-3-ols to influence the growth of intestinal bacterial groups, we have carried out the in vitro fermentation, with human faecal microbiota, of two purified fractions from grape seed extract (GSE): GSE-M (70% monomers and 28% procyanidins) and GSE-O (21% monomers and 78% procyanidins). Samples were collected at 0, 5, 10, 24, 30 and 48 h of fermentation for bacterial enumeration by fluorescent in situ hybridization and for analysis of phenolic metabolites. Both GSE-M and GSE-O fractions promoted growth of Lactobacillus/Enterococcus and decrease in the Clostridium histolyticum group during fermentation, although the effects were only statistically significant with GSE-M for Lactobacillus/Enterococcus (at 5 and 10 h of fermentation) and GSE-O for C. histolyticum (at 10 h of fermentation). Main changes in polyphenol catabolism also occurred during the first 10 h of fermentation; however, no significant correlation coefficients (P > 0.05) were found between changes in microbial populations and precursor flavan-3-ols or microbial metabolites. Together, these data suggest that the flavan-3-ol profile of a particular food source could affect the microbiota composition and its catabolic activity, inducing changes that could in turn affect the bioavailability and potential bioactivity of these compounds.

Capability of Lactobacillus plantarum IFPL935 to catabolize flavan-3-ol compounds and complex phenolic extracts

Lactobacillus plantarum IFPL935 was incubated with individual monomeric flavan-3-ols and dimeric A- and B-type procyanidins to identify new metabolites and to determine the effect of compound structural features on bacterial growth and catabolism. Complex extracts rich in A-type proanthocyanidins and phenolic acids from cranberry were also tested. The results showed that L. plantarum IFPL935 exhibited higher resistance to nongalloylated monomeric flavan-3-ols, A-type dimeric procyanidins, and cranberry extract than to (-)-epicatechin-3-O-gallate and B-type dimeric procyanidins. Despite these findings, the strain was capable of rapidly degrading (-)-epicatechin-3-O-gallate, but not A- or B-type dimeric procyanidins. However, it was able to produce large changes in the phenolic profile of the cranberry extract mainly due to the catabolism of hydroxycinnamic and hydroxybenzoic acids. Of most relevance was the fact that L. plantarum IFPL935 cleaved the heterocyclic ring of monomeric flavan-3-ols, giving rise to 1-(3',4'-dihydroxyphenyl)-3-(2″,4″,6″-trihydroxyphenyl)propan-2-ol, activity exhibited by only a few human intestinal bacteria.

Antibacterial activity of wine phenolic compounds and oenological extracts against potential respiratory pathogens

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 IC(50) . 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.

In vitro fermentation of a red wine extract by human gut microbiota: changes in microbial groups and formation of phenolic metabolites

An in vitro batch culture fermentation experiment was conducted with fecal inocula from three healthy volunteers in the presence and absence of a red wine extract. Changes in main bacterial groups were determined by FISH during a 48 h fermentation period. The catabolism of main flavonoids (i.e., flavan-3-ols and anthocyanins) and the formation of a wide a range of phenolic microbial metabolites were determined by a targeted UPLC-PAD-ESI-TQ MS method. Statistical analysis revealed that catechol/pyrocatechol, as well as 4-hydroxy-5-(phenyl)-valeric, 3- and 4-hydroxyphenylacetic, phenylacetic, phenylpropionic, and benzoic acids, showed the greatest increases in concentration during fermentation, whereas 5-(3'-hydroxyphenyl)-γ-valerolactone, its open form 4-hydroxy-5-(3'-hydroxyphenyl)-valeric acid, and 3,4-dihydroxyphenylacetic acid represented the largest interindividual variations in the catabolism of red wine polyphenols. Despite these changes, microbial catabolism did not produce significant changes in the main bacterial groups detected, although a slight inhibition of the Clostridium histolyticum group was observed.

Wine features related to safety and consumer health: an integrated perspective

This review presents a global view of the current situation of the scientific knowledge about aspects of wine with possible repercussions (positive or negative) on consumer health and wine safety. The presence in wine of some potential harmful compounds such as phytosanitary products, trace metal compounds, sulfites, and some toxics of microbial origin, such as ochratoxin A, ethyl carbamate, and biogenic amines, is discussed. The different strategies and alternative methodologies that are being carried out to reduce or to avoid the presence of these substances in wines are also discussed. In recent years much work has focused on establishing the scientific explanations for the positive biological effects of some wine compounds. In this review, we also examine the latest knowledge regarding wine and health, focusing on two types of compounds that have been related to the positive effects of moderate wine consumption, such as phenolic compounds and bioactive peptides.

Feasibility and application of liquid-liquid extraction combined with gas chromatography-mass spectrometry for the analysis of phenolic acids from grape polyphenols degraded by human faecal microbiota

In this study the feasibility of a LLE-GC-EI-MS method for the analysis of 43 phenolic acids belonging to different chemical structure families which have been described in the literature as microbial-derived metabolites after consumption of dietary polyphenols was proved. In addition, the method was applied for the characterisation of phenolic metabolites resulting from the incubation, in anaerobic conditions, of a commercial grape seed extract (GSE) and their corresponding flavan-3-ol monomeric (GSE-M) and oligomeric (GSE-O) fractions with human faeces from healthy volunteers (n=3). The method showed average values of repeatability and reproducibility of 5.0% and 6.3%, respectively, adequate and low detection (1.8-30.8 μg L(-1)) and quantification limits (6.0-102.8 μg L(-1)) and good recovery values (95%, as average value). A total of 27 phenolic acids were identified in the faecal solutions after incubation with the grape seed extracts. In general, faecal samples incubated with GSE and GSE-M (monomeric fraction) yield a higher formation of phenolic acids compared to the samples incubated with the oligomer fraction (GSE-O).

Synthesis, analytical features, and biological relevance of 5-(3',4'-dihydroxyphenyl)-γ-valerolactone, a microbial metabolite derived from the catabolism of dietary flavan-3-ols

The physiological significance of 5-(3',4'-dihydroxyphenyl)-γ-valerolactone, an important metabolite derived from the catabolism of flavan-3-ols by gut microbiota, has been often overlooked due to the lack of the commercial standard. In the present work, this metabolite has been chemically synthesized, and its analytical parameters and antioxidant capacity have been determined in comparison to other chemical analogues [isomer 3-(3',4'-dihydroxyphenyl)-δ-valerolactone and γ-valerolactone] and other structurally related compounds [(+)-catechin, (-)-epicatechin, and 3-(3,4-dihydroxyphenyl)-propionic acid]. The synthesized compound was also used to perform a targeted analysis in samples collected during the in vitro fermentation of a grape seed flavan-3-ol extract with human fecal microbiota from three healthy volunteers. The time-course formation of 5-(3',4'-dihydroxyphenyl)-γ-valerolactone revealed large interindividual differences among volunteers, with concentrations ranging from 3.31 to 77.54 μM at 10 h of fermentation. These results are further discussed in view of the scarce reports quantifying 5-(3',4'-dihydroxyphenyl)-γ-valerolactone in in vitro fermentation studies, and pharmacokinetic and intervention studies.

Potential of wine-associated lactic acid bacteria to degrade biogenic amines

Some lactic acid bacteria (LAB) isolated from fermented foods have been proven to degrade biogenic amines through the production of amine oxidase enzymes. Since little is known about this in relation to wine micro-organisms, this work examined the ability of LAB strains (n=85) isolated from wines and other related enological sources, as well as commercial malolactic starter cultures (n=3) and type strains (n=2), to degrade histamine, tyramine and putrescine. The biogenic amine-degrading ability of the strains was evaluated by RP-HPLC in culture media and wine malolactic fermentation laboratory experiments. Although at different extent, 25% of the LAB isolates were able to degrade histamine, 18% tyramine and 18% putrescine, whereas none of the commercial malolactic starter cultures or type strains were able to degrade any of the tested amines. The greatest biogenic amine-degrading ability was exhibited by 9 strains belonging to the Lactobacillus and Pediococcus groups, and most of them were able to simultaneously degrade at least two of the three studied biogenic amines. Further experiments with one of the strains that showed high biogenic amine-degrading ability (L. casei IFI-CA 52) revealed that cell-free extracts maintained this ability in comparison to the cell suspensions at pH 4.6, indicating that amine-degrading enzymes were effectively extracted from the cells and their action was optimal in the degradation of biogenic amines. In addition, it was confirmed that wine components such as ethanol (12%) and polyphenols (75 mg/L), and wine additives such as SO(2) (30 mg/L), reduced the histamine-degrading ability of L. casei IFI-CA 52 at pH 4.6 by 80%, 85% and 11%, respectively, in cell suspensions, whereas the reduction was 91%, 67% and 50%, respectively, in cell-free extracts. In spite of this adverse influence of the wine matrix, our results proved the potential of wine-associated LAB as a promising strategy to reduce biogenic amines in wine.

Determination of microbial phenolic acids in human faeces by UPLC-ESI-TQ MS

The aim of the present work was to develop a reproducible, sensitive, and rapid UPLC-ESI-TQ MS analytical method for determination of microbial phenolic acids and other related compounds in faeces. A total of 47 phenolic compounds including hydroxyphenylpropionic, hydroxyphenylacetic, hydroxycinnamic, hydroxybenzoic, and hydroxymandelic acids and simple phenols were considered. To prepare an optimum pool standard solution, analytes were classified in 5 different groups with different starting concentrations according to their MS response. The developed UPLC method allowed a high resolution of the pool standard solution within an 18 min injection run time. The LOD of phenolic compounds ranged from 0.001 to 0.107 μg/mL and LOQ from 0.003 to 0.233 μg/mL. The method precision met acceptance criteria (<15% RSD) for all analytes, and accuracy was >80%. The method was applied to faecal samples collected before and after the intake of a flavan-3-ol supplement by a healthy volunteer. Both external and internal calibration methods were considered for quantification purposes, using 4-hydroxybenzoic-2,3,4,5-d4 acid as internal standard. For most analytes and samples, the level of microbial phenolic acids did not differ by using one or another calibration method. The results revealed an increase in protocatechuic, syringic, benzoic, p-coumaric, phenylpropionic, 3-hydroxyphenylacetic, and 3-hydroxyphenylpropionic acids, although differences due to the intake were only significant for the latter compound. In conclusion, the UPLC-DAD-ESI-TQ MS method developed is suitable for targeted analysis of microbial-derived phenolic metabolites in faecal samples from human intervention or in vitro fermentation studies, which requires high sensitivity and throughput.

Sherry wines

Sherry wines are among the most distinctive Spanish wines, mainly produced in the southern Spain (particularly in Jerez and Montilla-Moriles), using traditional practices aimed at ensuring uniform quality and characteristics over time. Several types of Sherry wines are produced depending on the winemaking conditions. Fino-type wines are characterized by a dynamic biological aging, in which a layer of yeast grows in the surface of the wine (flor velum). On the contrary, Oloroso-type sherry wines are subjected to an oxidative aging, while Amontillado-type Sherries are produced by combining both production systems. Therefore, these wines undergo different biological and chemical processes that affect distinctively their chemical composition and their aroma and sensory characteristics. Through this review, the main aspects involved in the winemaking technology of sherry wines, and the latest scientific findings related to the microbiota of the flor film and other aspects associated to the changes in their chemical and sensory composition during aging will be revised. Some new trends in sherry wine technology focused on the acceleration of the biological aging or the use of organic grapes will be also considered.

Role of specific components from commercial inactive dry yeast winemaking preparations on the growth of wine lactic acid bacteria

The role of specific components from inactive dry yeast preparations widely used in winemaking on the growth of three representative wine lactic acid bacteria (Oenococcus oeni, Lactobacillus hilgardii and Pediococcus pentosaceus) has been studied. A pressure liquid extraction technique using solvents of different polarity was employed to obtain extracts with different chemical composition from the inactive dry yeast preparations. Each of the extracts was assayed against the three lactic acid bacteria. Important differences in the effect of the extracts on the growth of the bacteria were observed, which depended on the solvent employed during the extraction, on the type of commercial preparations and on the lactic acid bacteria species. The extracts that exhibited the most different activity were chemically characterized in amino acids, free monosaccharides, monosaccharides from polysaccharides, fatty acids and volatile compounds. In general, specific amino acids and monosaccharides were related to a stimulating effect whereas fatty acid composition and likely some volatile compounds seemed to show an inhibitory effect on the growth of the lactic acid bacteria. These results may provide novel and useful information in trying to obtain better and more specific formulations of winemaking inactive dry yeast preparations.

Antimicrobial activity of phenolic acids against commensal, probiotic and pathogenic bacteria

Phenolic acids (benzoic, phenylacetic and phenylpropionic acids) are the most abundant phenolic structures found in fecal water. As an approach towards the exploration of their action in the gut, this paper reports the antimicrobial activity of thirteen phenolic acids towards Escherichia coli, Lactobacillus spp., Staphylococcus aureus, Pseudomonas aeruginosa and Candida albicans. The growth of E. coli ATCC 25922 was inhibited by only four of the phenolic acids tested at a concentration of 1000 microg/mL, whereas pathogenic E. coli O157:H7 (CECT 5947) was susceptible to ten of them. The genetically manipulated E. coli lpxC/tolC strain was highly susceptible to phenolic acids. The growth of lactobacilli (Lactobacillus paraplantarum LCH7, Lactobacillus plantarum LCH17, Lactobacillus fermentum LPH1, L. fermentum CECT 5716, Lactobacillus brevis LCH23, and Lactobacillus coryniformis CECT 5711) and pathogens (S. aureus EP167 and C. albicans MY1055) was also inhibited by phenolic acids, but to varying extents. Only P. aeruginosa PAO1 was not susceptible to any of the phenolic compounds tested. Structure-activity relationships of phenolic acids and some of their diet precursors [(+)-catechin and (-)-epicatechin] were established, based on multivariate analysis of microbial activities. The antimicrobial properties of phenolic acids reported in this paper might be relevant in vivo.

Application of supercritical CO(2) extraction for the elimination of odorant volatile compounds from winemaking inactive dry yeast preparation

A procedure based on the application of supercritical CO(2) extraction to reduce and/or to remove odorant volatile compounds from a winemaking inactive dry yeast (IDY) preparation has been set up. By applying a factorial design, a screening of different temperatures and pressure conditions was assayed in order to determine the optimal deodorization conditions, and afterward the effect of several sample pretreatments was investigated. The best extraction conditions were achieved at 200 atm and 60 degrees C, applying the cryogenic grinding of the sample and using 40% (w/w) ethanol as cosolvent. By using these conditions, it was possible to reduce to approximately 70% of the volatile compounds present in the samples that may be released into the wines and therefore affecting their sensory characteristics. Odorant volatile compounds such as 2-methylhydroxypyrrole, 2-ethyl-6-methylpyrazine, and 2,3,5-trimethylpyrazine completely disappeared from the deodorized sample as verified by GC-O analysis. Additional experiments in model wines confirmed the low release of volatile compounds from the deodorized samples, without provoking any change to their nonvolatile composition (nitrogen compounds and neutral polysaccharides) that is related to the technological properties of these preparations.

Characterization of commercial inactive dry yeast preparations for enological use based on their ability to release soluble compounds and their behavior toward aroma compounds in model wines

The characterization of commercial enological inactive dry yeast (IDY) with different applications in wine production has been carried out. This study was based on the yeast's ability to release soluble compounds (high molecular weight nitrogen, free amino nitrogen, peptidic nitrogen, free amino acids, and polysaccharides) into model wines and on its behavior toward the volatility of seven wine aroma compounds. Important differences in soluble compounds released into the model wines supplemented with commercial IDY were found, with the free amino acids being among the most released. The volatility of most of the aroma compounds was affected by the addition of IDY preparations at a concentration usually employed during winemaking. The extent of this effect was dependent on the physicochemical characteristics of the aroma compound and on the length of time the IDY preparations remained in contact with the model wines. Whereas shorter contact times (2, 4, and 6 days) mainly promoted a "salting-out" effect, longer exposure (9 and 13 days) provoked a retention effect, with the consequent reduction of aroma compounds in the headspace. The use of different commercial preparations also promoted different effects toward the aroma compounds that may be at least in part due to differences in their ability to release soluble compounds of yeast origin into the wines.

Biogenic amine production by lactic acid bacteria isolated from cider

AIMS

To study the occurrence of histidine, tyrosine and ornithine decarboxylase activity in lactic acid bacteria (LAB) isolated from natural ciders and to examine their potential to produce detrimental levels of biogenic amines.

METHODS AND RESULTS

The presence of biogenic amines in a decarboxylase synthetic broth and in cider was determined by reversed-phase high-performance liquid chromatography (RP-HPLC). Among the 54 LAB strains tested, six (five lactobacilli and one oenococci) were biogenic amine producers in both media. Histamine and tyramine were the amines formed by the LAB strains investigated. Lactobacillus diolivorans were the most intensive histamine producers. This species together with Lactobacillus collinoides and Oenococcus oeni also seemed to produce tyramine. No ability to form histamine, tyramine or putrescine by Pediococus parvulus was observed, although it is a known biogenic amine producer in wines and beers.

CONCLUSIONS

This study demonstrated that LAB microbiota growing in ciders had the ability to produce biogenic amines, particularly histamine and tyramine, and suggests that this capability might be strain-dependent rather than being related to a particular bacterial species.

SIGNIFICANCE AND IMPACT OF THE STUDY

Production of biogenic amines by food micro-organisms has continued to be the focus of intensive study because of their potential toxicity. The main goal was to identify the microbial species capable of producing these compounds in order to control their presence and metabolic activity in foods.

Contribution of malolactic fermentation by Oenococcus oeni and Lactobacillus plantarum to the changes in the nonanthocyanin polyphenolic composition of red wine

The changes in the nonanthocyanin phenolic composition during red wine malolactic fermentation carried out spontaneously and by four different starter cultures of the species Oenococcus oeni and Lactobacillus plantarum were examined to determine whether differences in nonanthocyanin polyphenolic compounds could be attributed to the lactic acid bacteria (LAB) strain that performs this important step of the wine-making process. The polyphenolic compounds were analyzed by high-performance liquid chromatography with photodiode array detection and HPLC with electrospray ionization-mass spectrometry detection. The malolactic cultures selected for this study were indigenous wine LAB strains from the A.O.C. Rioja (Spain). Results showed different malolactic behaviors in relation to wine phenolic compositions for O. oeni and L. plantarum, and also, a diversity was found within each group. The hydroxycinnamic acids and their derivatives, the flavonols and their glycosides, the flavanol monomers and oligomers, and trans-resveratrol and its glucoside were the main compounds modified by the different LAB. The wild LAB population exerted a greater impact in the wine content of some of these phenolic compounds than the inoculated selected monocultures of this study.

Evidence for horizontal gene transfer as origin of putrescine production in Oenococcus oeni RM83

The nucleotide sequence of a 17.2-kb chromosomal DNA fragment containing the odc gene encoding ornithine decarboxylase has been determined in the putrescine producer Oenococcus oeni RM83. This DNA fragment contains 13 open reading frames, including genes coding for five transposases and two phage proteins. This description might represent the first evidence of a horizontal gene transfer event as the origin of a biogenic amine biosynthetic locus.

Biogenic amines in natural ciders

Biogenic amines play an important physiological role in mammals, and high amounts of some exogenous amines in human diet may contribute to a wide variety of toxic effects. These amines are commonly found in many foodstuffs, particularly in fermented products such as cheese, meat products, beer, wine, and ciders. Here, the level of biogenic amines in some natural ciders was examined. Twenty-four samples of cider purchased from commercial sources were analyzed by reverse-phase high-performance liquid chromatography and fluorescence detection after precolumn derivatization with o-phthaldialdehyde. Amine levels were variable, ranging from not detected to 23 mg/liter. The average level of total biogenic amines in ciders was 5.94 +/- 8.42 mg/liter. Putrescine, histamine, and tyramine were the prevailing amines being present in 50.0, 37.5, and 33.3% of the ciders studied; very small amounts of ethylamine and phenylethylamine were observed in only one sample. Other cider parameters were analyzed to determine whether they affect the biogenic amine content in ciders, and the results were evaluated by applying cluster analysis and principal component analysis. Ciders that showed lower glycerol contents and higher amounts of 1,3-propanediol had much higher levels of histamine, tyramine, and putrescine, suggesting a high activity of lactic acid bacteria during cider making and thus the need for effective control of lactic acid bacteria.

Chiral MEKC-LIF of amino acids in foods: Analysis of vinegars

The formation of D-amino acids (D-aa's) in many fermented foods depends, among other factors, on the particular fermentation conditions, the action and autolysis of the microorganisms involved. In this sense, the analysis of chiral amino acids is an interesting analytical strategy for food scientists, since these compounds can be used as bacterial markers and can help, e.g., to detect adulterations, microbiological contaminations, etc. In this work, a fast and sensitive method based on MEKC-LIF has been developed to analyze and quantitate L-amino acid (L-aa) and D-aa in vinegars. The chiral MEKC-LIF procedure uses 100 mM sodium tetraborate, 30 mM SDS, and 20 mM beta-CD at pH 9.7 as running buffer, obtaining a good separation of the main vinegar L-/D-aa previously derivatized with fluorescein isothiocianate. Namely, L/D proline, alanine, arginine, glutamic, and aspartic acid, plus the nonchiral amino acid gamma-aminobutyric acid are separated in less than 20 min with high efficiency (up to 720,000 plates/m) and good sensitivity (LODs lower than 16.6 nM were achieved). Several D-aa's were detected and quantified in balsamic, sherry, white wine, and cider vinegars using this MEKC-LIF procedure, observing interesting differences in their L-aa and D-aa profiles and contents.

Formation of biogenic amines throughout the industrial manufacture of red wine

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.

Wine volatile and amino acid composition after malolactic fermentation: effect of Oenococcus oeni and Lactobacillus plantarum starter cultures

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.