Antioxidant and antimicrobial activities of various leafy herbal teas

We evaluated the antioxidant and antimicrobial activities of various leafy herbal tea (LHT) extracts, including rooibos, green tea, black tea, rosemary, lemongrass, mulberry leaf, bamboo leaf, lotus leaf, peppermint, persimmon leaf, and mate tea. To compare the antioxidant activities of various LHTs, samples of each were extracted with 80 °C water or 20 °C ethanol, and their total phenolic content (TPC), total flavonoid content (TFC), 2,2-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity, 2,2-azinobis-3 ethyl benxothiazoline-6-sulphonic acid (ABTS) radical cation decolorization activity, ferric reducing power, and ferrous ion chelating effect were measured. Green tea ethanol extract showed the highest antioxidant activity in all assays except the ferrous ion-chelating assay. Water extracts of green tea and black tea and ethanol extracts of rosemary, mate, and persimmon leaf teas also exhibited considerable antioxidant potential, followed by the green tea ethanol extract. Minimum inhibitory concentrations (MIC) and minimum lethal concentrations (MLC) were determined to verify the antimicrobial activities of the LHT extracts against two oral pathogens (Streptococcus mutans and Streptococcus sobrinus) and three food-borne pathogens (Listeria monocytogenes, Shigella flexneri, and Salmonella enterica). Among the tested LHTs, green tea ethanol extract had potent antimicrobial activity against all five pathogens, and the mate tea water extract was the most effective against Gram-positive bacteria. Consequently, green tea ethanol extracts had the most powerful antioxidant and antimicrobial properties, suggesting their potential application as a health-promoting functional ingredient or natural preservative in foods.     

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.     

In vitro antimicrobial activity of less-utilized spice and herb extracts against selected food-borne bacteria

In this study we compared the antimicrobial activities of extracts from four under-utilized spices and herbs including goraka (Garcinia quaesita), galangal (Alpinia galanga), lemon iron bark (Eucalyptus staigerana) and mountain pepper (Tasmannia lanceolata) to the three common spices and herbs pepper (Piper nigrum), rosemary (Rosmarinus officinalis), and oregano (Oreganum vulgare). Different extraction solvents were used (water, ethanol and hexane) and extracts were tested against four food-borne bacteria (Escherichia coli, Salmonella Typhimurium, Listeria monocytogenes and Staphylococcus aureus) using agar disc diffusion and broth dilution assays. Solvent type greatly influenced the antimicrobial activity of the spice and herb extracts except for those of P. nigrum, which had little or no activity. In general the spice and herb extracts with antimicrobial activity were more effective against Gram-positive than Gram-negative bacteria. Extracts from the under-utilized herbs and spices had significant activity. In particular, A. galanga hexane and ethanol extracts and E. staigerana ethanol and water extracts had strong antimicrobial activity against S. aureus and/or L. monocytogenes. Interestingly the minimal inhibitory concentrations determined using the broth dilution method and the diameter of inhibition zones using the disc diffusion assay were not strongly correlated (r² ranged from 0.10 to 0.70) in most extracts, suggesting that choosing just one method for antimicrobial testing may lead to indefinite conclusions. The total phenolic content of two extracts from each spice and herb was assayed to establish any relationship between antimicrobial activity and phenolic compound levels, however this was found to poorly correlated (r² < 0.30). This study has demonstrated that simple extracts of novel under-utilized herbs and spices have potential antimicrobial activity against food-borne bacterial species. Further it is indicated that the antimicrobial activity in some herbs and spices may be due to the presence of substances other than phenolic compounds.     

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.     

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.     

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.     

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 Ethanolic Jik (Barringtonia acutangula) leaf extract and its application for shelf-life extension of Pacific white shrimp meat during refrigerated storage

Plant extracts can serve as natural preservatives in seafood and they are gaining a tremendous amount of attention due to the deleterious effects of the synthetic counterparts. Despite the several advantages of plant extracts particularly in terms of safety, green color caused by chlorophylls limit their uses. In this study, ethanolic plant leaf extracts from some Thai indigenous plants including Noni, soursop, and Jik, were prepared, followed by dechlorophyllization via sedimentation method. Chlorophyll a, chlorophyll b and total chlorophyll were removed by more than 60%. The extraction yield, total phenolics and total flavonoids, antioxidant, and antibacterial activities of all the dechlorophyllized ethanolic plant leaf extracts varied. Among all the extracts, Jik leaf extract (JLE80) prepared using 80% ethanol showed the highest antioxidant and antibacterial activities. LC-MS/MS profiling revealed that quercetin 3-(2-galloylglucoside) was the most abundant phenolic compound in JLE, which more likely played a significant role in its antioxidant and antimicrobial functions. When butterfly shrimp (BS) was treated with JLE (200–600 mg/L) and stored at 4 ^ᵒC for 15 days, BS treated with JLE at 400 and 600 mg/L had the retarded bacterial spoilage and chemical deterioration as indicated by lower microbial counts and lipid oxidation. As a result, the shelf-life of BS was extended to 12–15 days, whereas the control could be kept for 9 days.     

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.     

Prevalence,molecular identification and antimicrobial resistance profile of Salmonella serovars isolated from retail beef products in Mansoura,Egypt

The present study was undertaken to determine the prevalence of Salmonella in 270 raw meat samples (90 each of fresh beef, ground beef, and beef burger) purchased on nine occasions from various supermarkets and butchers' shops in Mansoura city, Egypt. Using conventional biochemical identification, Salmonella species were recovered from 23.3% (21/90), 20% (18/90), and 12.2% (11/90) of fresh beef, ground beef and beef burger samples, respectively with an overall prevalence of 18.5% (50/270) among all the meat products examined. Higher prevalence were obtained based on molecular identification, by detecting gyrB and invA genes, which verified the presence of Salmonella species in 30.0% (27/90), 26.7% (24/90), and 16.7% (15/90) of fresh beef, ground beef, and beef burger samples, respectively with an overall prevalence of 24.4% (66/270) among all the meat products tested. Of the 2635 presumptive colonies tested, 228 were biochemically identified as Salmonella, while 272 were molecularly identified as Salmonella, which were all positive for the enterotoxin (stn) virulent gene. Of the 272 serologically tested strains, 266 were serologically identified into six Salmonella serovars, while 6 strains were untypable. Salmonella Typhimurium and Salmonella Enteritidis were the most prevalent serovars with an incidence of 38.2% (104/272) and 34.6% (94/272), respectively. The other four serovars identified were Salmonella Haifa, Salmonella Muenster, Salmonella Virchow, and Salmonella Anatum were detected at lower prevalences of 11% (30/272), 7.4% (20/272), 4% (11/272) and 2.6% (7/272), respectively. Interestingly, the antimicrobial susceptibility testing indicated that all of the 100 Salmonella serovars tested were multidrug resistant (resistant to three or more antibiotics). Our findings demonstrated that the retail beef products tested were widely contaminated with multidrug-resistant Salmonella and such contamination may constitute a major public health concern.     

Prevalence of Salmonella in raw minced meat,raw fresh sausages and raw burger patties from retail outlets in Gaborone,Botswana

The prevalence of Salmonella in raw minced meat, raw burger patties and raw fresh sausages was determined by analysing 122 minced meat, 120 sausages and 58 burger patties obtained from retail outlets in Gaborone, Botswana. The prevalence rate was 20%. The most prevalent serogroups were B, followed by C and E/G. The Salmonella enterica serovars isolated were S. Typhi, S. Enteritidis, S. Anatum, S. Reading, S. Melagridis, S. Typhimurium, S. Paratyphi B, S. Newport, S. Bovis-morbificans, S. Braenderup, S. Infantis, S. Tennessee and S. Montevideo. The presence of S. Typhi and Paratyphi in meat products indicate human origin and therefore poor personal hygiene during handling of the meat products. Multidrug resistance patterns involving sulphatriad, sulphafurazole, tetracycline and cotrimoxazole were observed. Isolates in serogroups B and C were resistant to a greater number of antibiotics than isolates from other serogroups.     

Antimicrobial effect of cranberry juice and extracts

The antimicrobial effect of cranberry juice and of three cranberry extracts (water-soluble (E1) and apolar phenolic compounds (E2), and anthocyanins (E3)) 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). Each cranberry sample was analyzed to determine the minimum inhibitory concentration (MIC) and the maximal tolerated concentration (MTC) at neutral pH. 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. The extract rich in water-soluble phenolic compounds caused the most important growth inhibitions. The bacteria ERV, and to a lesser degree, P. aeruginosa, S. aureus and E. coli ATCC 25922, were the most sensitive to the antimicrobial activity of extract E1. The growth of P. aeruginosa and E. coli ATCC was also affected by the presence of the anthocyanin-rich cranberry extract E3, although the observed antibacterial effect was not as important as with extract E1. In general, L. monocytogenes, E. coli O157:H7 and S. Typhimurium were the most resistant to the antibacterial activity of the cranberry extracts. Within 30 min of exposure with pure neutralized cranberry juice, L. monocytogenes and ERV were completely inactivated.     

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.     

Antimicrobial effect of blueberry (Vaccinium corymbosum L.) extracts against the growth of Listeria monocytogenes and Salmonella Enteritidis

This study examined the antimicrobial effect of blueberry (Vaccinium corymbosum L.) extracts obtained from four cultivars (Elliott, Darrow, Bluecrop, and Duke) on the growth of Listeria monocytogenes and Salmonella Enteritidis. The minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of the extracts against L. monocytogenes and S. Enteritidis in tryptic soy broth were determined. Concentrations of total phenolic compounds and four individual phenolic (chlorogenic acid, ellagic acid, quercetin, and quercetin-3-galactoside) in the extracts were determined using Folin-Ciocalteau method and HPLC analysis, respectively. All four extracts at 112.5–900 mg/mL exhibited a dose-dependent growth-inhibitory effect against L. monocytogenes and S. Enteritidis. L. monocytogenes was significantly more sensitive to the antimicrobial effect of the extracts than S. Enteritidis. Phenolic compounds in the extracts such as chlorogenic acid, quercetin, ellagic acid, and quercetin-3-galactoside were the active antimicrobial compounds in the blueberry extracts. The results of this study suggest that blueberry extract or extract-derived components may be used to control pathogenic microorganisms. More studies on the use of blueberry as a natural antimicrobial in food products are warranted.     

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.     

Chinese red pepper (Zanthoxylum bungeanum Maxim.) leaf extract as natural antioxidants in salted silver carp (Hypophthalmichthys molitrix) in dorsal and ventral muscles during processing

Chinese red pepper (Zanthoxylum bungeanum Maxim.) leaf (ZML) extract contains high amounts of phenolic compounds possessing high total antioxidant capacity and hydroxyl, 1, 1-dipheny-2-picrylhydrazyl (DPPH) free radical scavenging activity. ZML extract was investigated as a natural antioxidant for the lipid stability of salted silver carp (Hypophthalmichthys molitrix) throughout salting and drying. Both dorsal and ventral muscles were examined for differences in moisture content, salt content, total lipid content, and degree of lipid oxidation. The hexanal content, Thiobarbituric acid reactive substances (TBARS) value, and lipoxygenase (LOX) activity in the ventral muscle were significantly higher than those of the dorsal muscle (p < 0.05). In the treatments with ZML extract, the hexanal content, the TBARS value, and the LOX activity were significantly lower (p < 0.05) during processing both in the dorsal and ventral muscles. The sensory qualities of processed salted fish could be improved with the amount of 0.030% extract in the dorsal muscle and 0.045% extract in the ventral muscle. These results showed that ZML extract can be a source of natural antioxidants and used as a food additive.     

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.     

Screening of Turkish endemic Teucrium montbretii subsp. pamphylicum extracts for antioxidant and antibacterial activities

The antioxidant and antimicrobial activities of Teucrium montbretii Bentham subsp. pamphylicum P.H. Davis (Lamiaceae) methanolic extracts were investigated. Total contents of phenolic compounds, flavonols and flavanols were determined by Folin–Ciocalteu colorimetric, Neu’s reagent solution and vanillin colorimetric methods, respectively. Total phenolics were 99.4 mg gallic acid equivalents (GAE)/g. Total flavanols and flavonols were 43.8 mg catechin equivalents (CE)/g and 0.5 mg rutin equivalents (RE)/g, respectively. At 100 ppm, the free radical scavenging activity was 58.6%. Antioxidant activity measured by the phosphomolybdenum method was 191.5 mg/g. Antibacterial activity was assessed (1%, 2.5%, 5%, 7.5% and 10% w/v) by the agar diffusion method against 10 species. Concentrations of 1% and 2.5% were not effective against any of the bacteria. The most resistant bacterium was Salmonella typhi while Listeria monocytogenes showed the highest sensitivity.     

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.     

Binary combinations of BHA and other natural and synthetic phenolics: Antimicrobial activity against Staphylococcus aureus and antioxidant capacity

Antibacterial activity against nineteen Staphylococcus aureus strains of five phenolic compounds (PCs) (hydroquinone, carvacrol, thymol, gallic acid and octyl gallate) was assessed in binary combinations with butylated hydroxyanisole (BHA). An antagonistic effect between BHA and each of the other PCs tested in combination was observed against 67% (for BHA + thymol) to 95% (BHA + octyl gallate) of the S. aureus strains, and no interaction effect was observed for the rest of the strains. Only slight differences in the antagonistic effect were detected among the strains of the different origins, between 80% (dairy) to 88% (meat). Concerning to the antioxidant activity, the combinations studied were mostly additive, with the exception of BHA + carvacrol and BHA + thymol that were antagonistic. It is concluded that the antagonic/no interaction antimicrobial effects of BHA + PCs against S. aureus are of interest to the food industry as they may determine the effectivity of active antimicrobial individual PCs and then, the safety of foods, when they coincide voluntarily or accidentally in foods.