Influence of phenolic compounds from wines on the growth of Listeria monocytogenes

The anti-microbial properties against Listeria monocytogenes of pure flavonoids rutin, catechin and quercetin; non-flavonoids gallic, vanillic, protocatechuic and caffeic acids and total polyphenols of three Argentinean wines, Cabernet Sauvignon, Malbec and Merlot varieties were investigated. The non-flavonoid caffeic acid and the flavonoids rutin and quercetin were the compounds with higher inhibitory activities on L. monocytogenes growth. The knowledge of the anti-listerial effect of different wines varieties could be the basis to demonstrate if the wine consumption with a meal may collaborate in the health protection against some foodborne organisms such as L. monocytogenes.     

Antimicrobial activity of phenolic compounds of wine against Campylobacter jejuni

Campylobacter jejuni is a food pathogen which causes gastrointestinal conditions with an ever-increasing incidence at a global level. The antimicrobial power of wine and its components has been studied. Wines having 11.5% ethanol significantly reduced the viability of C. jejuni when they were diluted to 25% in water. The microbicidal power of red wine was higher than that of white wine. While pH does not seem to affect the viability of this pathogen, different phenolic compounds have an effect on it when tested at concentrations from 0 to 1000 mg/L. Gallic acid and p-hydroxybenzoic acid reduced the viability of C. jejuni at concentrations as low as 1 mg/L, but quercetin and catechin did not even affect it at concentrations of 1000 mg/L. Methyl gallate, epicatechin, synaptic acid, vanillic acid, and caffeic acid were microbicidal at concentrations starting at 10 mg/L. Tryptophol, ferulic acid, and cumaric acid were effective starting at 100 mg/L. According to this, wine constitutes an adverse environment for the survival of this pathogen. Furthermore, it would be interesting to study the possible use of phenolic compounds in wine as an alternative to the use of antimicrobial growth promoters against these bacteria in broilers.     

The antimicrobial effect of wine on Bacillus cereus in simulated gastro-intestinal conditions

This study aimed to evaluate the antimicrobial activity of wine against Bacillus cereus vegetative cells and spores. The results clearly show that wine exerts a strong inactivation effect against vegetative cells of B. cereus. The red wine tested inactivated stationary phase cultures to undetectable numbers in less than 10 s. Thus, further inactivation assays were carried out with wine diluted with water (1:4 and 1:8). Diluted wine 1:4 caused a reduction of approximately 5 log cycles on viable cell counts in 20 s. On the other hand, B. cereus spores were found to be highly resistant to wine exposure. The influence of wine components (organic acids, ethanol and phenolic compounds) was investigated on vegetative cells. The wine organic acids tested exhibited a strong inactivation effect, and, when combined with ethanol, a slight synergistic effect was observed. The wine phenolic compounds assayed displayed no activity against the vegetative cells at the concentrations tested. At the simulated gastric conditions studied (in the presence of food), wine diminished considerably the number of B. cereus viable cells in addition to the effect of the synthetic gastric fluid. The behaviour of B. cereus spores under gastro-intestinal conditions was also evaluated. In a consumption-like scenario, the addition of wine led to lower total counts (vegetative cells + spores) of B. cereus in the simulated intestine conditions, showing that wine inhibits the proliferation of the vegetative cells obtained from the germination of spores. This work provides evidence that consumption of wine during a meal may diminish the number of viable cells of B. cereus and reduces the impact of the germination of spores that may occur in the small intestine, thus lowering the risk of toxi-infection that may be caused by this pathogen.     

High performance liquid chromatography analysis of phenolic substances in Greek wines

Eleven samples of commercially available Greek wines were analyzed in order to determine the phenolic content. For the analysis, reversed phase-high performance liquid chromatography (RP-HPLC) coupled with diode array detection was used. The most abundant phenolic substance detected was (+)-catechin (11.8–40 mg l⁻¹). Red wines contained more phenolic substances than white ones. The effect of aging in oak wood barrels on phenolics was also investigated. Specific types of Greek white wines, “retsina”, were also analyzed. Pitch, which is added to such types of wines, contributes significantly to the increased amount of phenolic compounds present in the wine.     

Putrescine production from agmatine by Lactobacillus hilgardii: Effect of phenolic compounds

The influence of phenolic compounds on the growth of Lactobacillus hilgardii X₁B and putrescine formation was assayed at concentrations normally present in wine. Agmatine degradation increased growth and survival of the microorganism and the alkalinity of the media. Bacterial growth was stimulated by phenolic compounds, except for gallic acid and quercetin. Putrescine formation from agmatine diminished in the presence of protocatechuic, vanillic and caffeic acids, and the flavonoids catechin and rutin. The concentration of phenolic compounds decreased after five days of incubation of L hilgardii X₁B, except for gallic acid and quercetin. The results indicate that phenolic compounds, besides their already known beneficial properties to human health, seem to be a natural way of diminishing putrescine formation.     

Antimicrobial and antioxidant activity of pressurized liquid extracts from oenological woods

The main goal of this study was to evaluate the antimicrobial activity of a collection of oenological woods extracts (non-toasted and toasted American oak wood, non-toasted and toasted French oak wood, non-toasted and toasted Rumanian oak wood, chestnut, cherry and wine grape wood) isolated by pressurized liquid extraction in order to control the microbial spoilage of wines. Inhibition of the growth of six wine lactic acid bacteria (LAB) (Lactobacillus hilgardii CIAL-49, Lactobacillus casei CIAL-52, Lactobacillus plantarum CIAL-92, Pedioccocus pentosaceus CIAL-85, Oenococcus oeni CIAL-91 and CIAL-96), two acetic acid bacteria (AAB) (Acetobacter aceti CIAL-106 and Gluconobacter oxydans CIAL-107) and three Brettanomyces yeast (Brettanomyces bruxellensis CIAL-108, CIAL-109 and CIAL-110) by the oenological wood extracts was assessed. The antioxidant activity and the total phenol index of wood extracts were also evaluated. Results confirmed differences in bacteria and yeast susceptibility to oenological wood extracts among different genera and species. Among them, AAB were especially sensitive to the phenolic inactivation from oenological woods extracts. Contrarily, amongst LAB, L. hilgardii CIAL-49 was the most resistant strain to the action of the wood extracts. Cherry wood was active against 9 of the 11 strains tested meanwhile French, Rumanian oak wood and chestnut show the lowest values of IC₅₀ for A. aceti CIAL-106. No significant correlation was found between antimicrobial activity either with antioxidant activity or with the total phenol content, suggesting that structure-function of the phenolic extracts has a greater influence on the antimicrobial activity than the total phenol content.     

Chemical composition and in vitro antimicrobial,antifungal and antioxidant properties of essential oils obtained from some herbs widely used in Portugal

The aim of this study was determine (i) the chemical composition (ii) the antimicrobial activity (antibacterial and antifungal) and (iii) the antioxidant activity by means of four different antioxidant tests (DDPH, FIC, FRAP and TBARS) of the EOs of three aromatic herbs, Coriander (Coriandrum sativum), celery (Apium graveolens) and bush-basil (Ocimum minimum) widely used in Portugal.There is a great variability of the compounds presented in the three tested essential oils. Bush-basil EO had the highest total phenolic content (794.9 mg GAE/L) while coriander EO had the lower total phenolic content (52.3 mg GAE/L). Since bush-basil had the highest TPC it was expected to present a very high antioxidant profile, which was verified in 3 of the 4 assays (DPPH inhibition of 95.9%; FRAP values of 2.7 mmol Trolox/L; TBARS inhibition of 87.2%); coriander, despite the low TPC showed the highest inhibition in the FIC assay (94.1%).The bush-basil EO showed the highest antimicrobial activity, with MIC ranging between 0.6 and 5 μL/mL against bacteria and 0.04–2.5 μL/mL against yeasts. Both celery and coriander EO had a very similar antimicrobial activity against all the tested strains. The antifungal activity was higher in the bush-basil EO against Mucor racemosus and Penicillium chrysogenum since it was the only EO that showed growth inhibition on all the tested concentrations. Alternaria alternata showed great resistance against all the tested essential oils.     

Differentiation of barrel-aged wines according to their origin,variety, storage time and enological parameters using fermentation products

The aim of this paper was to study the presence of fermentation products in quality Spanish wines aged in oak barrels. Two hundred and forty Spanish wines aged in barrels were analyzed and statistically treated for differentiation according to their origin, variety, storage time, and enological parameters. The results showed that the alcoholic degree of wines increased with ageing time, and geographical areas could also be differentiated by the alcoholic degree. Moreover, we observed a higher alcoholic degree in wines from the area with the lowest annual rainfall, regardless of storage time. A relation was also observed between the content of fermentation products of wines and the alcoholic degree and total acidity, although the varietal factor and ageing time modulate the concentration of these compounds. Thus, wines elaborated with Cabernet Sauvignon presented the highest concentrations of esters, while those with Cencibel had the highest concentrations of fatty acids. Wines that were aged the longest in barrels had higher concentrations of ethyl esters of organic acids, so they can be considered markers of ageing.     

trans-Resveratrol in wines from the major Greek red and white grape varieties

Stilbenes, in particular trans-resveratrol and its glucoside, are widely reported to be beneficial to health, having been shown to posses anti-oxidative, anti-carcinogenic, and anti-tumour properties. trans-Resveratrol (trans-3,5,40-trihydroxystilbene), a phenolic compound present in grapes, wines, and peanuts, has been reported to have health benefits including anti-carcinogenic effects and protection against cardiovascular diseases. A direct injection-HPLC method, based on existing methods slightly modified was used to analyze wines from the major red and white Greek grape varieties (Vitis vinifera L.) for their trans-resveratrol content. Red wines were found to have higher concentrations of trans-resveratrol (0.352–1.99 mg/l) compared with those produced from white varieties (0.005–0.57 mg/l). It was also interesting that red wines produced from the native Greek varieties, Kotsifali, Mandilaria and Agiorgitico, appeared to contain important amounts of trans-resveratrol.     

Bordeaux red wines display variable intrinsic ability to support Brettanomyces bruxellensis growth

Red wines constitute a major production in Bordeaux vineyards but to ensure the quality of these wines, winemakers should limit the development of the spoilage yeast Brettanomyces bruxellensis. Therefore, the growth of five representative strains of B. bruxellensis in 53 sulphite-free Bordeaux red wines was examined and differences between them were found regarding the ability to support the yeast growth. Thanks to a notation method and unsupervised classification analysis, we classified the wines according to their “permissiveness”. The key factors modulating the permissiveness score were the wine ethanol content, the yeast strain and the wine itself (domain, vintage or batch). The pH had little effect. The wine composition analysis (Proton Nuclear Magnetic Resonance (¹H NMR) analysis of 43 compounds) did not enable to find the molecules responsible for the wine permissiveness.     

Antioxidant and antimicrobial activities of leafy green vegetable extracts and their applications to meat product preservation

Leafy green vegetables (LGV) are rich in phenolic compounds that have a wide range of biological functions, including antioxidant and antimicrobial activities. Our first goal was to evaluate the antioxidant and antimicrobial activities of 70% ethanolic extracts of ten LGV commonly consumed in East Asia. To determine antioxidant activity, we measured total phenolic content (TPC), 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, 2,2-azinobis-3 ethyl benxothiazoline-6-sulphonic acid (ABTS) cation decolorization activity, and reducing power. For the analysis of antimicrobial activity, the inhibitory effects of the extracts against Escherichia coli, Salmonella enterica, Shigella flexneri, Listeria monocytogenes, Staphylococcus aureus, and Bacillus subtilis were evaluated using agar well diffusion and broth-microdilution tests. Among all LGV, extracts of chamnamul (Pimpinella brachycarpa) and fatsia (Aralia elata) exhibited outstanding antioxidant and antimicrobial properties, and we thus investigated the influences of these extracts on lipid oxidation and microbial criteria in raw beef patties. The extracts and butylated hydroxytoluene (BHT, a positive control) were individually added to patties at both 0.1% and 0.5% (w/w) concentrations and the patties were stored at 4 °C for 12 days. The color parameters and thiobarbituric acid reactive substances (TBARS) values were monitored periodically, and a microbial analysis was performed. The addition of extracts and BHT resulted in concentration-dependent decreases in TBARS values and in the number of microorganisms in the beef patties and also improved meat color stability. The fatsia extract had more effective antioxidant and antimicrobial activities than the chamnamul. We conclude that extracts of LGV, especially fatsia, have potential as natural preservatives for meat products.     

Application of experimental design and response surface methodology to optimize the procedure to obtain a bactericide and highly antioxidant aqueous extract from orange peels

In recent years there is a growing demand for healthy and safe food, without added preservatives or synthetic antioxidants. In this regard, plant extracts have promising future due to their high contents of bioactive compounds, especially in phenolic and polyphenolic compounds that exhibit antimicrobial and antioxidant activities. For this reason, the plant extracts could form the basis of many applications, including the preservation of fresh and processed foods. In this work, the methodology to obtain orange peel extracts with high bioactive properties is presented. To adjust the extraction conditions, experimental design and response surface methodology were applied to establish the optimum value of all the experimental variables that have influence in the extraction system. Total phenolic contents and antioxidant activity values were used as response parameter. The peel extracts, obtained with the proposed methodology, exhibited a high content of phenolic compounds, high antioxidant and antimicrobial activity, against Escherichia coli and Listeria innocua (in-vitro experiments). Finally, to demonstrate the feasibility of the peel extracts, they were used as natural additive in apple juice reducing significantly juice browning and the microbial load for both bacteria.     

Antimicrobial effects of fractions from cranberry products on the growth of seven pathogenic bacteria

The antimicrobial effect of thirty HPLC fractions of different polarity obtained from two cranberry juices and three extracts (anthocyanins, water-soluble and apolar phenolic compounds) isolated from frozen cranberries and pomace was investigated against seven bacterial strains (Enterococcus faecium resistant to vancomycin (ERV), Escherichia coli O157:H7 EDL 933, Escherichia coli ATCC 25922, Listeria monocytogenes HPB 2812, Pseudomonas aeruginosa ATCC 15442; Salmonella Typhimurium SL1344 and Staphylococcus aureus ATCC 29213) The minimum inhibitory concentration (MIC) and the maximal tolerated concentration (MTC) of each fraction were determined for each pathogen using a 96-well microtiter plate method. The results, reported in μg phenol/mL, indicated that all the bacterial strains, both Gram-positive and Gram-negative, were selectively inhibited by the cranberry phenolic compounds. All pathogens were very sensitive to at least seven fractions with MTCs below 2 μg phenol/mL and five fractions with MICs below 10 μg phenol/mL. In addition, four fractions rich in apolar phenolic compounds were very efficient against all bacteria with MICs below 10 μg phenol/mL, and twenty five fractions completely inhibited microbial growth with MICs below100 μg phenol/well. L. monocytogenes exhibited the highest sensitivity with twelve very active fractions (MTCs and MICs below 1 and 10 μg phenol/mL, respectively) while E. coli O157H7 was the least sensitive to twenty seven fractions (with the highest MICs). Also, it appears that the technological process to manufacture cranberry juice can reduce the antimicrobial activity of phenolic fractions.     

Evaluation of the antimicrobial activity of aqueous extracts from dry Vaccinium corymbosum extracts upon food microorganism

As blueberries are rich in phenolic compounds, which possess a demonstrated antimicrobial activity, it may be interesting to further elucidate its real potential and properties. As such, the main goal of this work was to evaluate the potential antimicrobial activity of Vaccinium corymbosum dry fruits and leaves aqueous extracts against several contaminants/pathogenic microorganisms while at the same time assessing the effect of V. corymbosum over lactic acid bacteria.     

Assessment of polyphenolic profile and antibacterial activity of pomegranate peel (Punica granatum) flour obtained from co-product of juice extraction

The aim of this work were to determine the polyphenolic profile and the antibacterial properties of pomegranate peel flour (PPF), in view to its application in the food industry as potential antimicrobial “natural” agent. For thus, the antibacterial properties of PPF were tested against: Listeria monocytogenes, Listeria innocua, Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli and Salmonella sp. bacterial strains. The polyphenolic profile was determined by HPLC. The Total Phenolic and Total Flavonoid content were also determined. The HPLC analysis of the PPF, showed a total of eight phenolic compounds. Punicagalin was the main component found in PPF (16.67 mg/g) followed by ellagic acid (0.15 mg/g). PPF had antibacterial activity against all bacteria tested with minimal inhibitory concentrations comprised between 20 and 50 mg/mL. The antimicrobial activity was in a decreasing order: Salmonella sp = E. coli = S. aureus = L. monocytogenes > P. aeruginosa > L. innocua. The antibacterial properties of pomegranate peel flour suggested that it is a promising antibacterial agent.     

A new fear in wine: Isolation of Staphylococcus epidermidis histamine producer

Biogenic amines (BAs) are undesirable compounds in all foods and beverages because they may induce food-borne intoxications when consumed at high concentrations. The aim of this study was to identify the organism responsible for the synthesis of histamine in a Tempranillo red wine from Ribera de Duero D.O. (Denomination of origin), Spain. Bacteria present in wines after malolactic fermentation were isolated, identified and typed. Four strains of the species Oenococcus oeni and two strains of Staphylococcus epidermidis were found. None of the O. oeni strains produced histamine, cadaverine or putrescine, but one of the S. epidermidis strains (Pa) was able to produce all three in synthetic medium and grape must, although not in wine. From the data obtained in this work, histamine present in Tempranillo wine B was produced by the S. epidermidis strain Pa. This is the first report in which the presence of S. epidermidis has been reported in wine and whose ability to produce histamine, putrescine and cadaverine has been demonstrated in grape must.     

Antimicrobial phenolic extracts able to inhibit lactic acid bacteria growth and wine malolactic fermentation

The purpose of this study was to determine whether phenolic extracts with antimicrobial activity may be considered as an alternative to the use of sulfur dioxide (SO₂) for controlling malolactic fermentation (MLF) in winemaking. Inhibition of the growth of six enological strains (Lactobacillus hilgardii CIAL-49, Lactobacillus casei CIAL-52, Lactobacillus plantarum CIAL-92, Pediococcus pentosaceus CIAL-85, Oenococcus oeni CIAL-91 and O. oeni CIAL-96) by phenolic extracts (n = 54) from different origins (spices, flowers, leaves, fruits, legumes, seeds, skins, agricultural by-products and others) was evaluated, being the survival parameter IC₅₀ calculated. A total of 24 extracts were found to significantly inhibit the growth of at least two of the LAB strains studied. Some of these extracts were also active against two acetic acid bacteria (Acetobacter aceti CIAL-106 and Gluconobacter oxydans CIAL-107). Transmission electron microscopy of the bacteria cells after incubation with the phenolic extract confirmed damage of the integrity of the cell membrane. Finally, to test the technological applicability of the extracts, the eucalyptus extract was added (2 g/L) to an industrially elaborated red wine, and the progress of the MLF was evaluated by means of residual content of malic acid. Addition of the extract significantly delayed the progress of both inoculated and spontaneous MLF, in comparison to the control wine (no antimicrobial agent added), although not as effective as K₂S₂O₅ (30 mg/L). These results demonstrated the potential applicability of phenolic extracts as antimicrobial agents in winemaking.     

Analysis of commercial wines by LC-MS/MS reveals the presence of residual milk and egg white allergens

Fining agents of animal origin are commonly used in winemaking process to clarify and stabilize wines and to optimize their organoleptic properties thanks to the removal of phenolic compounds that cause bitterness and astringency. Considering the potential allergenicity of proteins used as fining agents, the need of label declaration for wines treated with such compounds is compelling. However, the difficulties in detecting proteins in a wine matrix by immunological assays have given rise to a search for alternative methods that can overcome the limitations of classical approaches. Mass spectrometry (MS) has recently emerged as a powerful and sensitive technique to detect residual fining proteins in wines. In this study we show that a simple and straightforward mass spectrometric approach can be used to reliably detect egg and milk allergens in commercial bottled wines. We tested 25 different wines by liquid chromatography coupled with tandem MS (LC-MS/MS) and found proteins of animal origin in 8 samples, so demonstrating that the proposed method allows to monitor the presence of potential allergenic proteins in fined commercial wine.     

Evaluation of volatile compound and food additive contents in blackberry wine

In addition to the biologically nutritious components present in wine, there can be substances that are harmful to human health. For this reason, the purpose of this study was to evaluate the contents of volatile compounds and food additives in blackberry wine samples produced from conventionally and organically grown blackberries and compare their concentrations with the maximum acceptable levels in wines for the first time. Volatile compounds were analyzed in 15 blackberry wines using a GC-FID method, while the contents of food additives were determined using a newly developed HPLC method. Both methods were validated for their linearity, sensitivity, repeatability, and intermediate precision. The major volatile compound in blackberry wine samples was ethanol (7.11–15.33%). The second most prevalent volatile compound found in all blackberry wine samples was methanol (174.2–641.4 mg/L), which is highly toxic. The amount of ethyl acetate in the investigated samples ranged from 53.8 to 188.4 mg/L, while propan-1-ol was found in three of the organic samples. Although isoamyl alcohol was found in all samples, the measured values ranged from 56.7 to 226.9 mg/L. The obtained results demonstrated that the concentrations of benzoic acid in the analyzed blackberry wines varied from 4.36 to 18.55 mg/L. The presence of sorbic acid has was detected in seven samples, and the values were in the range of 1.43–54.48 mg/L. Salicylic acid is a natural component of blackberry fruit, and the contents of this phytochemical in the studied wines were between 1.99 and 13.55 mg/L. The saccharin concentrations were detected in three samples, and the highest value was 31.51 mg/L. The concentrations of amyl alcohol, acesulfame, aspartame and caffeine were found to be below the quantitation limits of the method in the investigated blackberry wines. Furthermore, the obtained data provide evidence that the contents of methanol in blackberry wines were above the permissible limits, except for four conventional blackberry wines. Thus, the concentrations of analyzed volatile substances measured in blackberry wines necessitate more extended investigations of these volatile compounds in this popular fruit wine.     

In vitro assessment of synthetic phenolic antioxidants for inhibition of foodborne Staphylococcus aureus,Bacillus cereus and Pseudomonas fluorescens

Minimal inhibitory concentrations (MICs) of seven synthetic phenolic compounds, five commonly used as antioxidants (TBHQ, BHA, BHT, propyl gallate and octyl gallate) and two as antimicrobials (propyl 4-hydroxybenzoate and n-heptyl 4-hydroxybenzoate) were assessed against several strains of two Gram-positive (Staphylococcus aureus and Bacillus cereus) and one Gram-negative (Pseudomonas fluorescens) bacteria, by using a standardized microdilution assay (ISO 20776-1, 2006). Octyl gallate was the most effective compound against the three genera/species of bacteria considered simultaneously (with the exception of four strains of B. cereus, which were resistant for this compound) with MIC values (≤100 μg/ml) lower than the concentrations usually used as antioxidants. TBHQ and n-heptyl 4-hydroxybenzoate were also effective in the control of S. aureus at very low concentrations (MIC of 3.1 μg/ml and 12.5 μg/ml, respectively). Propyl 4-hydroxybenzoate was the most inhibitory phenolic compound against all strains of B. cereus and both tested parabens (propyl- and heptyl-) were not effective for P. fluorescens (MIC > 1600 μg/ml). B. cereus was the bacterial genera that showed more intra-species variation, distinguishing two clearly groups of sensitivity among the strains to octyl gallate and n-heptyl 4-hydroxybenzoate (“sensitive” with mean MICs of 42.8 and 4.2 μg/ml, respectively; and “resistant” with MICs >1600 and >800 μg/ml, respectively). According to all that, octyl gallate would be an interesting phenolic compound for the food industry, not only because of its recognized antioxidant properties but also because of their effectivity as antimicrobial against S. aureus, B. cereus and P. fluorescens.