In vitro evaluation of antibacterial and antioxidant activities of the essential oil and methanol extract of endemic Zataria multiflora Boiss

The present study was conducted to evaluate in vitro antibacterial and antioxidant properties of essential oil and methanol extracts from a unique and endemic plant, Zataria multiflora Boiss. The antibacterial test results showed that the essential oil of the plant strongly inhibited the growth of all of the microorganisms studied especially the Gram-negative strains. The polar fraction of methanol extract has been effective against Gram-positive strains, while the non-polar fraction has shown activity similar to essential oil. The antioxidant potential of the samples was evaluated using two separate methods, inhibition of free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ammonium thiocyanate systems. Sub fractions of the methanol extract were able to reduce the stable free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) with an IC₅₀ of 11.7 ± 1.58 and 16.2 ± 1.61 μg/ml, respectively for non-polar and polar ones, which the activity of the latter almost is equal to synthetic antioxidant BHA (18.2 ± 1.94 μg/ml). Inhibition values of linoleic oxidation were calculated to be 82.4% and 80.3% for the polar and non-polar fractions, respectively. The essential oil to be showed more inhibition (89.7 ± 2.5), similar to the synthetic antioxidants BHA (97.8 ± 2.94) and ascorbic acid (93.2 ± 2.1). The chemical composition of hydrodistilled essential oils of Z. multiflora was analyzed by GC/MS. A total of 25 compounds representing 99.78% of the oil were identified: thymol (37.59%), carvacrol (33.65%); para-cymene (7.72%), γ-terpinene (3.88%) and β-caryophyllene (2.06%) were the main components comprising 84.9% of the oil. Results here show that the essential oil and methanol extract of Z. multiflora possess antioxidant and antibacterial activity, and therefore it could be used as a natural preservative ingredient in food and/or pharmaceutical industries.     

The in vitro antimicrobial and antioxidant activities of the essential oils and methanol extracts of endemic Thymus spathulifolius

The present study was conducted to evaluate the in vitro antimicrobial and antioxidant properties of essential oil and methanol extracts from a unique and endemic plant, Thymus spathulifolius (Hausskn. and Velen.). The antimicrobial test results showed that the essential oil of T. spathulifolius strongly inhibited the growth of test microorganisms studied, except for 4 fungi species while polar and non-polar subfractions of the methanol extract had moderate antibacterial, but not antifungal and anticandidal activity. The antioxidative potential of the samples was evaluated using two separate methods, inhibition of free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) and β-carotene–linoleic acid systems. The polar subfraction of the methanol extract was able to reduce the stable free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) with an IC₅₀ of 16.15 ± 0.5 μg/ml, which was lower than that of synthetic antioxidant, BHT, (19.8 ± 0.5 μg/ml). Inhibition values of linoleic acid oxidation were calculated as 92% and 89% for the oil and the polar subfraction, respectively. Gallic acid equivalent total phenolic constituent of the polar subfraction was 141.00 ± 0.90 μg/mg (14.1%, w/w). The chemical composition of a hydrodistilled essential oil of T. spathulifolius was analyzed by a GC and GC/MS system. A total of 28 constituents representing 99.2% of the oil were identified; thymol (36.5%), carvacrol (29.8%), p-cymene (10.0%) and γ-terpinene (6.3%) were the main components comprising 82.6% of the oil. Results presented here may suggest that the essential oil and extracts of T. spathulifolius possess antimicrobial and antioxidant properties, and therefore, they can be used as a natural preservative ingredient in food and/or pharmaceutical industry.     

In vitro antioxidant and antibacterial activities of essentials oils obtained from Egyptian aromatic plants

The aim of this work was to (i) determine the chemical composition of the essential oils (EOs) of five spices widely cultivated in Egypt as: Fennel (Foeniculum vulgare), parsley (Petroselinum crispum), lavender (Lavandula officinalis), black cumin (Nigella sativa) and thyme (Thymus vulgaris); (ii) determine the total phenolic compound (TPC) content (iii) determine the antioxidant activity of the Egyptian essentials oils by means of three different antioxidant test and (iv) determine the effectiveness of the Egyptian essentials oils on the inhibition of the growth of some indicators of spoilage bacteria strains. There is a great variability in the chemical composition of EOs obtained from the five Egyptian aromatic plants. Thyme EO had the highest content of total phenols (913.17 mg GAE/L). Black cumin (highest % of inhibition of DPPH radical: 95.89% and highest FRAC values 3.33 mmol/L Trolox) and thyme (highest % of inhibition of TBARS: 80.76) essential oils presented the best antioxidant profile. Only the essential oil of thyme showed inhibitory effects on the three tested bacteria at all added doses.     

Influences of ripening stages and extracting solvents on the polyphenolic compounds,antimicrobial and antioxidant activities of blueberry leaf extracts

This study investigated polyphenols, antimicrobial and antioxidant activities of blueberry leaf extracts harvested at three fruit ripening stages (immature, semi-mature, and commercial-mature) and extracted by three solvents (95% ethanol, 70% acetone, and 100% methanol). Quercetin, kaempferol, gallic, protocatechui, caffeic, vanillic, syringic, p-coumaric, and ferulic acids were identified in the extracts with varied amount depending on ripeness stage and extraction solvent. Protocatechui and ferulic acids were not detected at semi-mature samples, and none protocatechui, syringic and p-coumaric acids in ethanol-extracts from commercial-mature samples. All extracts exhibited antimicrobial activity against Escherichia coli and fungi, but only semi-mature and commercial-mature samples were against Listeria monocytogenes and Staphylococcus aereus. Methanol- and acetone-extracts had higher polyphenol content, DPPH and reducing power than those of ethanol-extracts, whereas opposite trend was observed in ORAC values. These results indicated the potentials of using blueberry leaf extracts as natural antimicrobial and antioxidant substance for food applications.     

Evaluation of the antiradical and antioxidant potential of grape extracts

Grape seed and bagasse extract obtained from Narince grape cultivar using different solvent mixtures were assayed for their antioxidant properties. Total phenolic contents of the extracts were determined by the Folin-Ciocalteu method. Antioxidant activities of the extracts at different concentrations were evaluated using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging, hydrogen peroxide scavenging and phosphomolybdenum methods. Also the extracts, as natural antioxidants, were assayed during eight weeks storage of refined poppy oil at 70 °C. For this reason peroxide value was used as a criterion to assess the antioxidant activity of grape extracts.The grape seed extracts showed strong antioxidant activity, by measuring their capacity to scavenge DPPH and hydrogen peroxide; to reduce Mo(VI) to Mo (V) and to decrease in the rate of peroxide formation, when compared to bagasse extract. Antioxidant activities of the extracts increased when the extract concentration increased.     

Evaluation of the antimicrobial and antioxidant activities of essential oils, extracts and their main components from oregano from Madeira Island, Portugal

Origanum vulgare subsp. virens growing wild in Madeira Island, Portugal was studied within the ongoing investigations on polymorphic Lamiaceae species. The antimicrobial activity of the essential oils and n-hexane extracts of origanum was determined against 10 strains of bacteria and yeasts, found as human pathogenic or food spoilage microorganisms. The essential oils, n-hexane extracts and isolated compounds showed moderately activity, compared to standard antibiotics, inhibiting all tested bacteria except Pseudomonas aeruginosa. The most sensitive microorganism was Mycobacterium smegmatis, reaching MIC = 25 μg mL⁻¹. The results obtained suggest a potential application of these oils in preventing the human pathogenic and food spoilage due to microorganism’s growth. The essential oils and n-hexane extracts have greater RSC than polar extracts, probably due to the high contents in thymol, which demonstrated the highest activity in the DPPH assay. All studied origanum samples showed a large content in non-esterified 1-hexacosanol, C₂₆H₅₄O, accumulated mainly in bracts and flowers.     

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.     

Probiotic potential,antimicrobial and antioxidant activities of Enterococcus durans strain LAB18s

The probiotic potential, antimicrobial and antioxidant properties of Enterococcus durans LAB18s, a strain capable of selenium bioaccumulation, was investigated. E. durans LAB18s showed resistance to acid conditions, showing ability to survive in the presence of simulated gastric juice at pH 3. This bacterium also survived in the presence of simulated intestinal juice with or without bile salts, and did not show hemolytic activity. The antimicrobial activity of culture supernatant and intracellular extract of E. durans LAB18s was tested against different pathogenic microorganisms, namely Listeria monocytogenes, Escherichia coli, Bacillus cereus, Staphylococcus aureus, Salmonella Typhimurium, Salmonella Enteritidis, Pseudomonas aeruginosa, Aeromonas hydrophila and Corynebacterium fimi. E. durans LAB18s exhibited a broad inhibitory spectrum, except to B. cereus, S. aureus and S. Enteritidis when the culture supernatant was used, and to S. Typhimurium when the intracellular extract was tested. The antioxidant activity of culture supernatant and intracellular extract of E. durans LAB18s was analyzed by ABTS⁺ and DPPH methods, and only culture supernatant presented ability to scavenge both radicals. Both culture supernatant and intracellular extract showed high antioxidant activity when analyzed by TBARS method. E. durans LAB18s could be useful as a source of dietary selenium supplementation.     

Antimicrobial and antioxidant activities of Chinese sumac (Rhus typhina L.) fruit extract

Sumac plant (Rhus typhina) is mainly used for forestation and gardening, whereas its fruit can be used to prepare a kind of beverage called “sumac-ade” and to treat gastrointestinal disorders. This study aimed at assaying the antimicrobial and antioxidant activities of R. typhina growing in China. The antimicrobial activity of R. typhina fruit extract was tested against twelve strains including Gram-positive and Gram-negative bacteria as well as yeasts. The extract showed a strong antimicrobial activity with a concentration-dependence and a broad antimicrobial spectrum for all tested bacteria species. Bacillus cereus and Helicobacter pylori were found to be the most sensitive Gram-positive and Gram-negative bacteria respectively, with a minimum inhibitory concentration (MIC) of 0.10%. However, yeasts exhibited much lower sensitivity, with MICs of 0.60–0.75%. Furthermore, the antioxidant activity of the extract was investigated, including scavenging activity of 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals (0.016 mg/ml as IC₅₀ value) and reducing power (IC₅₀ value of 0.041 mg/ml). To our knowledge, this is the first report on the biological activities of R. typhina fruit extract and our findings suggest the possibility of using the fruit of R. typhina as a novel source of natural antimicrobial and antioxidant agents for the food and pharmaceutical industries.     

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.     

Effect of gamma irradiation and extended storage on selected chemical constituents and antioxidant activities of sliced mushroom

Due to its exquisite odor and taste, Boletus edulis Bull.: Fr. mushroom is being increasingly used throughout the world. However, the availability of this product is highly restrained by its seasonality and perishability, demanding special care to keep its quality. Furthermore, mushrooms are often distributed in sliced form, and the slicing operation requires special treatments, besides augmenting the possibility of microbial contamination. Some techniques are currently applied to sliced mushrooms, but these processes had adverse effects on nutrients, odor, texture and taste, besides requiring expensive equipment. Food irradiation is being studied as an alternative technology to improve the quality and durability of determined products, having been previously applied in several mushroom species. Herein, gamma irradiation was applied to dried and sliced samples of B. edulis, at high doses (2, 6 and 10 kGy), and the effects on nutritional, chemical and antioxidant parameters were evaluated throughout storage (6 and 12 months). The results obtained for the chemical parameters do not advised storing B. edulis for such extended periods, since some relevant changes were detected, especially in samples stored for 12 months. In general, the gamma irradiation treatment did not cause further changes in the chemical composition, besides having a slightly positive effect in keeping the antioxidant activity and most of the bioactive compounds profiled in this work, contributing to maintain the potential health effects of this exquisite food, even after extended storage periods.     

In vitro antibacterial and antioxidant properties of chitosan edible films incorporated with Thymus moroderi or Thymus piperella essential oils

The aim of this work was to evaluate chitosan edible films incorporated with the EOs of two aromatic herbs, Thymus moroderi and Thymus piperella for (i) the growth inhibition of some bacterial strains (ii) their total phenolic content (TPC), and (iii) their antioxidant activity by means of three different antioxidant tests to define if the chitosan edible films incorporated with these EOs could be used as natural active films for food use. The agar disc diffusion method was used to determine the antibacterial activities of chitosan edible films. For the antioxidant activity, three different analytical assays were used (DPPH, FRAP and FIC). The chitosan films containing T. piperella EO (CH + TPEO) were more effective (p < 0.05) against Serratia marcenscens and Listeria innocua than chitosan films containing T. moroderi EO (CH + TMEO), while no statistically differences were found (p > 0.05) between CH + TPEO and CH + TMEO against Aeromonas hydrophila and Achromobacter denitrificans. The CH + TMEO films showed lower (p < 0.05) antioxidant activity, at all concentrations and with all methods assayed, than CH + TPEO. The antioxidant activity occurred in a concentration dependent manner.The results showed that chitosan edible films incorporated with T. piperella and T. moroderi EOs could be used as active films due to its excellent antibacterial and antioxidant activities.     

Biological activities of Boswellia sacra extracts on the growth and aflatoxins secretion of two aflatoxigenic species of Aspergillus species

Aflatoxins are the most serious carcinogenic, hepatotoxic, teratogenic and mutagenic secondary metabolites which adversely affect human and animal health. This study was designed to evaluate the in vitro inhibitory effect of different concentrations of Boswellia sacra resin (2.5, 5, 7.5 and 10 g/100 ml), leaf extract (5, 7.5, 10, 12.5 and 15 ml/100 ml), and essential oil (1, 2, 3, and 4 ml/100 ml) on the growth and aflatoxins production by two species of Aspergilli, namely Aspergillus flavus (SQU21) and Aspergillus parasiticus (CBS921.7). Resin of B. sacra caused 57.9–92.1% inhibition of aflatoxin secretion by A. flavus and 43.6–95.7% for A. parasiticus. However, the mycelial dry weights were significantly increased by 20.9–52.7% for A. flavus, and 8.9–68.5% for A. parasiticus. The leaf extract of B. sacra apparently enhanced aflatoxins production by 20–50%, and mycelial dry weight by 25.5–29.1% for A. flavus and A. parasiticus. The essential oil of B. sacra at different concentrations similarly inhibited the fungal growth and aflatoxins production by 45.8–83.7% for A. flavus and 41.3–83.5% for A. parasiticus which indicates the antifungal activity of this oil. None of the B. sacra extracts detoxified pure aqueous aflatoxin B₁. We have concluded that B. sacra resin and essential oil possess biological activity against biochemical synthesis and metabolic pathway of aflatoxin production of the two Aspergillus species. Therefore, the resin and essential oil of B. sacra can be recommended as safe plant based bioreservatives to enhance shelf life of food and feed products with reference to adverse effect of physical and synthetic chemical preservatives and their antimicrobial and aflatoxins inhibition activity.     

Antioxidant and anti food-borne bacterial activities of extracts from leaf and different fruit parts of Myristica fragrans Houtt

The main products of Myristica fragrans are the dried seed (nutmeg) and aril (mace), which are used as spices or condiments to flavor foods. In this study, its leaf and different parts of fruit (pericarp, aril, seed-kernel and shell) were compared for their total phenolic content, antioxidant and anti food-borne bacterial capacities. The 80% methanol extracts of aril, seed-kernel and shell shared the highest total phenolic content with shell extract acted as the greatest primary antioxidant, by having the highest ferric reducing antioxidant power (FRAP) activity (EC₅₀ 9.7 ± 0.1 μg/mL), β-carotene-bleaching activity (EC₅₀ 21.5 ± 2.7 μg/mL) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging activity (EC₅₀ 160.9 ± 13.9 μg/mL), whereas the pericarp extract exhibited highest secondary antioxidant activity as a metal chelator (EC₅₀ 75.6 ± 14.4 μg/mL). Only the aril and seed-kernel extracts were found to inhibit the food-borne bacteria with the lowest minimum inhibition concentration of 50 μg/mL, against Staphylococcus aureus (ATCC12600) and Bacillus cereus (ATCC10876). Our findings suggest the possibility of using the aril and seed-kernel extracts as natural food preservative and other parts as a new source of natural antioxidant for food and pharmaceutical industries.     

Effects of extraction methods of shiitake by-products on their antioxidant and antimicrobial activities in fermented sausages during storage

Two different solvents (water and ethanol/water at 50/50 ratio) were used for extraction of phenolic contents in shiitake by-products, and the antioxidant and antimicrobial efficacies of fermented sausages incorporated with these two extracts were investigated during storage. Also, shelf-life stability of fermented sausages fortified with these two extracts was compared with those fortified with BHT (0.02%) or nitrite (0.01%)/nitrate (0.005%). Significantly higher antioxidant activities (e.g., ferrous ion chelating and DPPH scavenging) and inhibitory capacity against lipid oxidation (e.g., TBARS reduction) were observed in the fermented sausages made with ethanolic extract (shiitake by-products extracted with ethanol/water) compared with those added with aqueous extract (extracted with water) or BHT, nitrite/nitrate and control throughout storage. The ethanolic extract treated-samples also showed a significantly slower increasing rate of total aerobic count (6.54–6.95 log₁₀ cfu/g) than the ones treated with aqueous extract (6.74–7.16 log₁₀ cfu/g) during storage. Otherwise, extract obtained from the ethanolic extract treated-samples had stronger antimicrobial activities against pathogens than the one obtained from aqueous extract treated-samples (e.g., minimum inhibitory concentrations, MIC = 2.05 & 3.64, 3.12 & 5.20 and 7.29 & 10.41 mg/mL for S. aureus, L. monocytogenes and E. coli O157, respectively). Especially, the antimicrobial activity against S. typhimurium (MIC = 37.50 mg/mL) was observed only in the extract of ethanolic extract treated-samples. Our study demonstrates that the extraction with ethanol/water solvent is a more effective method to obtain bioactive compounds enriched-extract which better improved the shelf-life stability of fermented sausages during storage without defects in quality in comparison to the extraction method with water.     

合成橡胶防老剂RD工艺路线的选择

介绍了合成防老剂RD的反应机理，综述了“两步法”、“一步法”和“改进一步法”3种合成RD工艺技术及其进展。从技术经济角度对“一步法”和“改进一步法”进行了分析对比，表明采用“改进一步法”工艺技术是目前合成RD的最佳工艺技术路线。     

Antimicrobial activities of red wine-based formulations containing plant extracts against Escherichia coli O157:H7 and Salmonella enterica serovar Hadar

We evaluated the antimicrobial activities of three red wine based plant extract/plant essential oil (EO) formulations: olive extract powder/oregano EO, apple skin extract powder/lemongrass EO, and green tea extract powder/bitter almond EO, and their formula permutations against the foodborne pathogens Escherichia coli O157:H7 and Salmonella enterica serovar Hadar. The following parameters that were expected to affect antimicrobial activity were evaluated: pH (3.6 or 7.0), temperature (4, 22, and 37 °C), incubation time (0, 5, 30, and 60 min) and bacterial load (∼10⁴ or ∼10⁹ bacteria/ml). The formulations with oregano, lemongrass, or bitter almond EO inhibited the growth of both pathogens at acidic pH with bacterial loads of ∼10⁴ or ∼10⁹ bacteria/ml. At neutral pH, the formulations were less effective. Although all the 3-component formulations were fast acting; showing significant activity in less than 5 min, only the activity of the lemongrass-containing formulation markedly increased with longer incubation times from 0 to 60 min. Activity also increased for all 3-component formulations with increasing temperature from 4 °C to 37 °C, although the activity of the lemongrass formulation appeared to level off at 22 °C. Of the tested formulations, the lemongrass EO formulations, at pH 3.6, appeared to be the most effective against the tested pathogens, especially against Salmonella. The most active formulations merit evaluation for antimicrobial efficacy in liquid and solid food.     

海洋油田缓蚀剂筛选及现场评价

海洋某油田注水管线发生较为严重的腐蚀,本文针对油田的现场环境,分析了油田的注水性质,筛选出一种效果优良的缓蚀剂配方HS-1,并通过LPR仪器探究其现场应用效果。现场试验表明:在20 mg/L加注浓度条件下,缓蚀剂HS-1可将腐蚀速率控制在0.030 7 mm/a左右,具有较好的缓释效果。     

Antibacterial activity of lactic acid bacteria against spoilage and pathogenic bacteria isolated from the same meat small-scale facility: 1—Screening and characterization of the antibacterial compounds

A total of 87 lactic acid bacteria (LAB) (36 Lactobacillus sakei, 22 Enterococcus faecium, 16 Lactococcus garvieae, 11 Vagococcus carniphilus and 2 Enterococcus sp.) isolated from a small-scale facility producing traditional dry sausages were screened for antagonistic activity against other LAB and some spoilage and pathogenic microorganisms, also isolated from the same processing facility, except Listeria innocua (in lieu of Listeria monocytogenes) and Escherichia coli. The final goal was to investigate LAB antibacterial activity within the facility microbial ecosystem and to select interesting strains for the role of bio-preservatives.Twenty-one Ec. faecium, 6 Vc. carniphilus, 4 Lc. garvieae, 3 Lb. sakei and 2 Enterococcus sp. were shown to inhibit the growth of some indicator microorganisms in an agar well diffusion assay. Except 2 Lb. sakei and an Enterococcus sp., all these isolates exhibited antibacterial activity against L. innocua, but only 3 Ec. faecium, 5 Vc. carniphilus and 3 Lc. garvieae displayed also antagonistic activity against Staphylococcus aureus. The 5 Vc. carniphilus isolates were also found to be inhibitory for the Gram-negative bacterium Hafnia alvei.Isolates displaying antibacterial activity against L. innocua and/or Sc. aureus were investigated for the nature of antibacterial compounds synthesized against these indicator microorganisms. Bacteriocin-like production could be detected only on agar plated in overlay assays, and was unsuccessfully researched in cell-free culture supernatant fluids under conditions that eliminate acid and hydrogen peroxide inhibition. Results also showed that a Lb. sakei isolate displayed an additional inhibitory effect by H₂O₂ against L. innocua. These isolates will be investigated for their ability to repress the growth of undesirable bacteria in biofilms, i.e., the real mode of bacterial attachment.This is the first report on bacteriocin-like from Vc. carniphilus and on bacteriocin-like from Lc. garvieae active against both L. innocua and Sc. aureus species.     

Different methods for control and comparison of the antioxidant properties of vegetables

The present study investigates the antioxidant properties of selected vegetables, using the total peroxyl radical-trapping parameter (TRAP), oxygen radical absorbance capacity (ORAC) and hydroxyl radical averting capacity (HORAC) methods. ORAC, TRAP and HORAC values well correlated with polyphenol content. A good correlation was found also between the methods for measuring antioxidant capacity. Nevertheless, ORAC has been found to be the most sensitive method to measure chain-breaking antioxidant activity. Although we have found a good correlation between TRAP, ORAC and HORAC, using more than one antioxidant assay is recommended for more detailed understanding the principles of antioxidant properties of samples.