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.     

Essential oils composition and bioactivities of two species leaves used as packaging materials in Xishuangbanna,China

This study reports the essential oils chemical composition and antioxidant and antimicrobial potentials of the leaves of Phrynium pubinerve Blume and Thysanolaena latifolia (Roxb. ex Hornem.) Honda, which are used as natural packaging materials by ethnic groups in Xishuangbanna, southwest China. GC–MS analysis identified 46 and 21 components, representing 88.6% and 93.4% of the essential oils of P. pubinerve and T. latifolia, respectively. The major constituents for P. pubinerve were (Z)-3-hexen-1-ol (17.31%), (E)-2-hexenal (9.01%) and 1-hexanol (8.61%). The major constituents for T. latifolia were (Z)-3-hexen-1-ol (28.79%), phytol (12.30) and (E)-β-ionone (9.54%). Both the essential oils and ethanol extracts showed antioxidant activity in DPPH test (IC₅₀ values = 192.47–706.07 μg/ml), ABTS assay (IC₅₀ values = 35.54–134.97 μg/ml) and FRAP assays. The essential oils showed considerable antimicrobial activity against pathogenic bacteria and spoilage organisms, with MIC and MBC values in the ranges of 64–3072 μg/ml and 64–4096 μg/ml, respectively. The bioactivities of these two plant species validate the traditional use of these two plants, suggesting that both could be new sources of natural antioxidant and antimicrobial agents for the packaging, medical and functional food industries.     

Inhibitory effects of selected plant essential oils on the growth of four pathogenic bacteria: E. coli O157:H7, Salmonella Typhimurium,Staphylococcus aureus and Listeria monocytogenes

Twenty eight essential oils were evaluated for their antibacterial properties, against four pathogenic bacteria (Escherichia coli O157:H7, Listeria monocytogenes 2812 1/2a, Salmonella Typhimurium SL 1344 and Staphylococcus aureus). Essential oils were introduced into Brain Heart Infusion agar (BHI) (15 ml) at a concentration of 0.003%, 0.006%, 0.013%, 0.025%, 0.05%, 0.1%, 0.2%, 0.4% and 0.8% (vol/vol) to determine the minimum inhibitory concentration (MIC) and the maximal tolerated concentration (MTC) for each pathogen evaluated. Results showed that the most active essential oils against bacteria tested were Corydothymus capitatus, Cinnamomum cassia, Origanum heracleoticum, Satureja montana, and Cinnamomum verum (bark). These showed a MIC ⩽ 0.05% (vol/vol) for all bacteria tested. For the MTC, with the exception of S. Typhimurium and L. monocytogenes where a MTC of 0.025% (vol/vol) was observed in presence of Cinnamomum verum and Cinnamomum cassia, respectively, a MTC ⩽ 0.013% (vol/vol) was observed for all other bacteria and the three other most active essential oils. Three oils (Satureja hortensis, Thymus vulgaris carvacroliferum, Origanum compactum) showed a MIC ⩽ 0.1% (vol/vol) for all bacteria tested. Seven oils (Thymus vulgaris thymoliferum, Thymus serpyllum, Thymus satureioides, Cymbopogon martinii, Pimenta dioica, Cinnamomum verum (leaf), Eugenia caryophyllus) showed a lower antimicrobial activity showing a MIC ⩽ 0.4% (vol/vol) against the four bacteria tested. Finally, 13 essential oils were less active showing a MIC value ⩾ 0.8% (vol/vol) against at least one bacterium.     

Antibacterial activity and chemical constitutions of Ziziphora clinopodioides

The essential oil and methanol extract obtained from aerial parts of Ziziphora clinopodioides Lam. harvested in the Eastern part of Turkey were evaluated for their chemical composition and antibacterial activity against 52 Gram-positive and Gram-negative bacteria. The GC–MS analyses allowed 18 compounds to be determined; the main constituents of the essential oils were (+)-pulegone (31.86%), 1,8-cineole (12.21%), limonene (10.48%), menthol (9.13%), β–pinene (6.88%), menthone (6.73%), piperitenone (5.30%) and piperitone (4.18%) The essential oil and methanol extract had a broad-spectrum antimicrobial activity against pathogens in broth microdilution bioassays. Maximum activity of essential oil (>22 mm) and methanol extract (>11 mm) was observed against Acidovorax facilis, Bacillus flexus, Bacillus spp, Bacillus sphaericus, Brevibacillus brevis, Corynebacterium ammoniagenes, Enterobacter sakazakii, Erwinia carotovora carotovora, Moraxella catarrhalis and Xanthomonas arboricola.     

Antimicrobial activity of essential oils against Escherichia coli O157:H7 in organic soil

Soil can be a significant source of preharvest contamination of produce by pathogens. Demand for natural pesticides such as essential oils for organic farming continues to increase. We examined the antimicrobial activity of several essential oils against Escherichia coli O157:H7 in soil. Two essential oils (cinnamaldehyde and eugenol), two bio-pesticides (Ecotrol and Sporan) containing essential oils, and an organic acid (acetic acid) at 0.5%, 1.0%, 1.5% and 2.0%, were mixed with organic sandy soil and inoculated with five different strains of E. coli O157:H7. Soils were incubated at room temperature (22 °C) and samples obtained at 1, 7 and 28 days were enumerated to determine survival. E. coli O157:H7 populations in soil were reduced by up to 5 log cfu/g after 24 h incubation at room temperature with 2% cinnamanaldehyde, Ecotrol, Sporan or vinegar. Reduction in E. coli O157:H7 by eugenol was not significantly different from control. Overall, E. coli O157:H7 strain 4406 was the most sensitive of all the five strains tested and cinnamaldehyde was superior to other treatments in reducing E. coli O157:H7 in soil. In general, increases in essential oil concentrations corresponded to reduced survival of E. coli O157:H7 with all oils used in this study. The results suggest that oils can reduce potential contamination of fresh organic produce inadvertently contaminated by soil.     

Disinfectant action of Cymbopogon sp. essential oils in different phases of biofilm formation by Listeria monocytogenes on stainless steel surface

Disinfectant solutions based on the essential oils of Cymbopogon citratus (D.C.) Stapf. and Cymbopogon nardus (L.) Rendle, applied alone or in combination, and a control disinfectant solution were tested in two phases (3 and 240 h) of biofilm formation by Listeria monocytogenes ATCC 19117 on AISI 304 (#4) stainless steel surface. Disinfectant solutions based on essential oils have effectively reduced the number of surface-adhered cells, especially after 60 min of contact. The disinfectant solutions based on a combination of essential oils were capable of reducing 100% (5.64 Log CFU cm⁻²) the number of surface-adhered cells after 60 min of contact, at 240 h of biofilm formation. Essential oils of C. citratus and C. nardus, alone or in combination, are new alternatives for disinfection of industrial stainless steel surfaces contaminated by L. monocytogenes.     

Antimicrobial properties of selected essential oils in vapour phase against foodborne bacteria

The aim of this study was to identify antimicrobial properties of essential oils in vapour phase. In vitro antibacterial activity against five foodborne bacteria (Escherichia coli, Listeria monocytogenes, Pseudomonas aeruginosa, Salmonella enteritidis, Staphylococcus aureus) was evaluated by disc volatilization method. The results were expressed as minimum inhibitory concentrations (MIC) in μl/cm³ of air. Thirteen of the 27 essential oils were active at least against one bacterial strain in the range of tested concentrations (0.0083–0.53 μl/cm³). The best results were shown by Armoracia rusticana (MIC 0.0083 μl/cm³) against all of the strains, followed by Allium sativum > Origanum vulgare > Thymus vulgaris > Satureja montana, Thymus pulegioides > Thymus serpyllum > Origanum majorana > Caryopteris x clandonensis, Hyssopus officinalis, Mentha villosa, Nepeta x faassenii, Ocimum basilicum var. grant verte. In conclusion, certain essential oils are highly effective in vapour phase and could be used in control of foodborne bacterial pathogens.     

Importance and efficiency of in-depth antimicrobial activity for the control of listeria development with nisin-incorporated sodium caseinate films

The effect of antimicrobial sodium caseinate-based films was investigated on inhibition of Listeria innocua in cheese. Nisin was incorporated into sorbitol-plasticized sodium caseinate films at 1000 IU/cm² and the films were prepared by casting methods. Mini red Babybel® cheese was chosen as a semi-soft cheese model. The antimicrobial activity was studied based on the contact between antimicrobial films and surface-contaminated as well as in-depth contaminated cheese samples during a 7-day storage at 4 °C. The active films produced resulted in a reduction of 1.1 log CFU/g reduction in L. innocua counts in surface-inoculated cheese samples after 1 week of storage as compared to control samples. Regarding in-depth inoculated cheese samples, antimicrobial effectiveness was found to be dependent on the distance from the contact surface with the films containing nisin to the cheese matrix. The inactivation rates obtained were 1.1, 0.9 and 0.25 log CFU/g with slice 1 (distance from contact surface d = 1 mm), slice 2 (d = 2 mm) and slice 3 (d = 3 mm), respectively. Our study demonstrates the potential application of antimicrobial films as a promising method to overcome problems associated with post-process contamination, thus enhancing the safety and extending the shelf life of food products.     

Pre-processed bovine milk quality in Trinidad: Prevalence and characteristics of bacterial pathogens and occurrence of antimicrobial residues in milk from collection centres

The study was conducted to assess the impact of the changes in the milk collection system in Trinidad (from twice daily collection to once, introduction of chilling facilities to the collection centres and transportation of milk to the processing plant in insulated truck instead of in metal churns at ambient temperature) on the microbial load and antimicrobial residue quality of the milk as well as the temperature and pH of milk, using standard methods. The presence of antimicrobial residues was detected using the Delvo test kit. Of a total of 266 milk samples from churns, the mean ± sd temperature and log₁₀ ± sd TAPC per ml was 20.36 ± 7.91 °C and 6.3 ± 1.09 respectively. For 20 milk samples from the chillers, the mean temperature and log₁₀ ± sd TAPC per ml was 15.10 ± 2.73 °C and 7.04 ± 0.33 respectively compared with corresponding values for 36 samples collected from the truck, 11.64 ± 4.22 °C and 7.11 ± 0.62 respectively (P < 0.05; X²). The mean TAPC, staphylococcal and E. coli counts per ml of milk from churns were significantly (P < 0.05; X²) higher for milk at low temperature (0–20 °C) compared with milk at high temperature (>30 °C). Eight (4.2%) of 192 milk samples tested contained antimicrobial residues. Of 168 S. aureus isolates tested, 24 (14.3%) were enterotoxigenic while 53 (45.3%) of 117 isolates tested exhibited resistance to various antimicrobial agents while of 386 isolates of E. coli tested, 3 (0.8%) were O157 strain and 129 (64.5%) of 200 isolates exhibited resistance to antimicrobial agents. It was concluded that despite the changes, the microbial load of milk was still high suggesting poor sanitary practices at the farm level. The detection of antimicrobial residues agents coupled with toxigenic S. aureus and E. coli isolates could pose health hazards to consumers.     

Comparative study of the simultaneous action of three essential oils on Aspergillus flavus and Sitophilus zeamais Motsch

Maize is among the most important produced and consumed crops in Cameroon. However, the availability of this cereal is limited by post-harvest losses, especially in the course of storage. Therefore, there is an urgent need to overcome this phenomenon through the use of efficient, cheap methods. To this effect, the simultaneous action of three essential oils, obtained by hydrodistillation from leaves of Ocimum gratissimum and Lippia rugosa and fruits of Xylopia aethiopica, on Aspergillus flavus and Sitophilus zeamais was investigated using a 2⁴ factorial design. The three essential oils and the storage time were considered as factors. The results revealed that low volume (60 μl/200 g grain) for O. gratissimum and high volume for L. rugosa (310 μl/200 g grain) and X. aethiopica (250 μl/200 g grain) showed the most important efficiencies against A. flavus and S. zeamais in a 2 weeks storage. Hence, the rate of mortality for S. zeamais was 92% and 89%, respectively, in samples of maize infested by S. zeamais and samples of maize infested by S. zeamais and A. flavus. Ninety five percent of A. flavus conidia were inhibited in samples of maize infested by A. flavus and samples of maize infested by S. zeamais and A. flavus.     

Essential oils to control Alternaria alternata in vitro and in vivo

The inhibitory effects of five essential oils (thyme, sage, nutmeg, eucaptus and cassia) against Alternaria alternata were tested at different concentrations (100–500 ppm) in vitro. The cassia oil and thyme oil both exhibited antifungal activity against A. alternata. The cassia oil inhibited completely the growth of A. alternata at 300–500 ppm. The thyme oil exhibited a lower degree of inhibition 62.0% at 500 ppm. Spore germination and germ tube elongation of the pathogens in potato dextrose broth was strongly inhibited in the presence of 500 ppm cassia oil. Irreversible inhibition of fungal growth could be caused by exposure to 300 ppm and 400 ppm cassia oil for 6 days and 500 ppm cassia oil for 3 days. Cassia oil at 500 ppm reduced the percentage of decayed tomatoes. The experiments on reducing natural decay development of tomatoes gave similar results. Therefore, essential oils could be an alternative to chemicals for control of postharvest phytopathogenic fungi on fruits or vegetables.     

Occurrence of diacetoxyscirpenol (anguidine) in processed cereals and pulses in Turkey by HPLC

The purpose of this study was to investigate the diacetoxyscirpenol (DAS, anguidine) level of contaminated cereal and pulse products in Turkey. DAS was detected using high performance liquid chromatography (HPLC) with diode array detector (DAD) at 205 nm and suspicious the results for two specimens suspected to contain DAS were confirmed by gas chromatography–mass spectrometry (GC–MS). An acetonitrile–water (21 + 4, v/v) extract of the sample was cleaned up on a column packed with alumina/charcoal (0.35 g + 0.40 g). The minimum detectable amount of DAS was 16 ng/injection, limit of detection was 0.8 μg/g for HPLC. A total of 85 commercially available cereal and pulse product samples, collected from markets and street bazaars, were analyzed. The recoveries for corn flour with the known amounts of DAS (2, 3, 4 μg/g) were 85.3% (SD 4.81, n = 5), 98.1% (SD 12.6, n = 5) and 96.4% (SD 3.2, n = 5), respectively. DAS was detected in none of the cereal and pulse products.     

Chemical constituents,antifungal and antioxidative potential of Foeniculum vulgare volatile oil and its acetone extract

GC and GC–MS analysis of Foeniculum vulgare volatile oil showed the presence of 35 components containing 96.4% of the total amount. The major component was trans-anethole (70.1%). The analysis of its acetone extract showed the presence of nine components accounting for 68.9% of the total amount. Linoleic acid (54.9%), palmitic acid (5.4%) and oleic acid (5.4%) were found as major components in extract. The antifungal and antioxidative potentials were also carried out by different techniques. In inverted petriplate method, the volatile oil showed complete zone inhibition against Aspergillus niger, Aspergillus flavus, Fusarium graminearum and Fusarium moniliforme at 6 μL dose. It was found to be effective for A. niger even at 4 μL dose. Moreover, using food poison technique, the volatile oil and extract both showed good to moderate zone of inhibition. The antioxidant value was evaluated by measuring peroxide and thiobarbituric acid values for linseed oil at fixed time intervals. Both, the volatile oil and extract showed strong antioxidant activity in comparison with butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT). In addition, their inhibitory action in linoleic acid system was studied by monitoring peroxide accumulation in emulsion during incubation through ferric thiocyanate method. The results were well correlated with the above results.     

The potential of some spice essential oils in the control of A. parasiticus CFR 223 and aflatoxin production

Essential oils of sweet basil (Ocimum basilicum), cassia (Cinnamomum cassia), coriander (Coriandrum sativum) and bay leaf (Laurus nobilis) at 1–5% (v/v) concentration in palm kernel broth inoculated with spore suspension (10⁶/ml) of Aspergillus parasiticus CFR 223 were evaluated for their potential in the control of aflatoxigenic fungus A. parasiticus CFR 223 and aflatoxin production. Healthy sorghum grains (120/treatment) immersed in the oils and distributed in three petri dishes with wet cotton wool were also inoculated with spore suspension (10⁶/ml) of A. parasiticus CFR 223 and assayed for grain protection. Sweet basil oil at optimal protective dosage of 5% (v/v) was fungistatic on A. parasiticus CFR 223 and aflatoxins produced in vitro and on fungal development on sorghum grains (P ⩽ 0.05) with a residual effect that lasted for 32 days. In contrast, oils of cassia and bay leaf stimulated the mycelia growth of the fungus in vitro but reduced the aflatoxin concentration (B₁ + G₁) of the fungus by 97.92% and 55.21% respectively, while coriander oil did not have any effect on both the mycelia growth and aflatoxin content of the fungus. The combination of cassia and sweet basil oils at half their optimal protective dosages (2.5% v/v) completely inhibited the growth of the fungus. The feasibility of implementing the results of this study to control aflatoxins was examined by the addition of whole and ground dry basil leaves at 5% and 10% (w/w), respectively, to 10 g sorghum, groundnut, maize and melon seed after 35 days storage period. It was found that the addition of whole and ground basil leaves markedly reduced aflatoxin contamination; however, 10% (w/w) of whole leaves was more effective as the reduction in aflatoxin was between 89.05% and 91%.The findings showed that aflatoxins can be controlled by co-storing whole sweet basil leaves with aflatoxin infected foods. The economic value of the study lies in the simplified technique for control of aflatoxin contamination in agricultural products and the benefits derivable from the use of local resources.     

Investigations on the essential oil of Lippia rugosa from Cameroon for its potential use as antifungal agent against Aspergillus flavus Link ex. Fries

Lippia rugosa essential oil was tested for its effectiveness against Aspergillus flavus on artificial growth media. The chemical composition of the oil was determined by gas chromatography–mass spectrometry (GC–MS). Geraniol (51.5%), nerol (18.6%) and geranial (10.4%) were the main components of Lippia oil. After 8 days of incubation on essential oil supplemented medium, mycelium growth of A. flavus was totally inhibited by 1000 mg l^?1 of L. rugosa essential oil. The effect of essential oil on aflatoxin B₁ synthesis was evaluated in SMKY broth. The medium supplemented with different essential oil concentrations, was inoculated with A. flavus mycelium and incubated at 25 °C. After 2, 4, 6 and 8 days, aflatoxin B₁ (AFB₁) was quantified in the supernatant using Enzyme Linked Immuno-Sorbent Assay (ELISA). Results showed that aflatoxin B₁ synthesis was inhibited by 1000 mg l^?1 of L. rugosa essential oil after 8 days of incubation. The effect of the EO on the H⁺-ATPase pumping membrane was also evaluated in the presence of several concentrations of oil (200–2000 mg l^?1) by monitoring glucose-induced acidification of the external medium. L. rugosa essential oil at the concentration of 2000 mg l^?1 completely inhibited the activity of this enzyme. These data suggest that the essential oil of L. rugosa is a fungicidal for A. flavus and its possible cellular target include the H⁺-ATPase.Results obtained in the present study indicate the possibility of exploiting Lippia rugosa essential oil in the fight against strains of A. flavus responsible for biodeterioration of stored foods products.     

Analysis of ethyl carbamate in Korean soy sauce using high-performance liquid chromatography with fluorescence detection or tandem mass spectrometry and gas chromatography with mass spectrometry

A specific, sensitive procedure involving high-performance liquid chromatography (HPLC) coupled to tandem mass spectrometry (MS/MS) was developed and compared to other analytical methods for quantification of ethyl carbamate (EC) in Korean soy sauce products. HPLC with a fluorescence detector was not applicable for monitoring trace amounts of EC in soy sauce due to its low detection limit (20 ppb). The use of gas chromatography (GC) coupled to MS could be applied to soy sauce, but it was not as simple and fast as HPLC/MS/MS. The GC/MS procedure exhibited excellent linearity over the concentration range of 10–200 ppb with a 0.5 ppb limit of detection (LOD) and 82.7 ± 3.1% recovery. A procedure involving HPLC/MS/MS with multiple reaction monitoring was developed. The characteristic transitions of m/z 90 → 62 for EC as well as m/z 104 → 62 for propyl carbamate (PC) as the internal standard were monitored. Good linearity was obtained both in the range from 10 to 100 ppb and in the range from 0.1 to 20 ppb with a LOD of 0.05 ppb. The average recovery was 92.2 ± 1.7%. The applicability of the GC/MS and developed HPLC/MS/MS methods was demonstrated by detection of EC in 12 kinds of commercial Korean soy sauce products at levels of 0.5 and 0.1 ppb, respectively. The new HPLC/MS/MS method provided greater sensitivity with a simpler and shorter confirmatory analysis than the GC/MS method.     

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.     

The inhibitory effect of black pepper on formation of heterocyclic aromatic amines in high-fat meatball

The effect of black pepper on the formation of heterocyclic aromatic amines (HCAs) in high-fat meatball fried at three different frying temperatures (175 °C, 200 °C, and 225 °C) was investigated. The fried samples were analyzed for five HCAs, including 2-amino-3-methylimidazo[4,5-f]quinoline (IQ), 2-amino-3,4-dimethylimidazo[4,5-f]quinoline (MeIQ), 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx), 2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline (4,8-DiMeIQx), and 2-amino-1-methyl-6-phenylimidazo[4,5-b] pyridine (PhIP). In control group meatballs without black pepper, the total HCAs amount increased in parallel with the frying temperature increased. The highest total HCA amount was found 37.81 ng/g in control group meatballs fried at 225 °C, 31.80 ng/g of which belonged to PhIP accounting.  The reduction of black pepper on PhIP compound was 100%. On the perspective of total HCA amount, black pepper has an inhibitory effect (ranging from about 12 to 100%). MeIQx was not detected in any of chops samples.     

Comparison of the effects of sesame and Thymbra spicata oil during the manufacturing of Turkish dry-fermented sausage

Effects of sesame, Thymbra spicata oil and BHT (butylated hydroxy toluene) on the quality and safety (pH, biogenic amine, TBARS values, colour and sensory attributes) of Turkish dry-fermented sausage were investigated during the ripening periods. A sharp decrease (P < 0.05) in pH values were observed from 5.84 to about 4.40 during the first 2 days of ripening. The TBARS value and putrescine concentration in recipes were found in the following order: control (S1) > BHT (S2) > sesame oil (S4) > Thymbra spicata oil (S3). Histamine and tyramine concentrations were highest (P < 0.05) in the control recipe, while lowest (P < 0.05) in Thymbra spicata and sesame oil added recipes. The most acceptable recipes were found to be the sesame oil added recipes with respect to their highest overall sensory quality scores. The order of acceptability was found to be S4 = S3 = S2 > S1. The pH, L, b, and YI-values were not significantly changed (P > 0.05) by the addition of Thymbra spicata oil, sesame oil, and BHT. These results indicated that the most effective antioxidant was found to be Thymbra spicata oil. This study pointed out that natural antioxidants could be easily utilized in sausages to enhance quality and get safe products.     

Prevalence of foodborne pathogens in open markets and supermarkets in Thailand

This study was conducted in Thailand (Bangkok and Pathum Thani provinces), from June 2006 to July 2007, in order to assess the prevalence of Listeria monocytogenes, Escherichia coli O157, Salmonella, Shigella and Vibrio parahaemolyticus in foods. Retail raw meats and seafood, including chicken (n = 109), pork (n = 80), beef (n = 108), shrimp (n = 43) and oysters (n = 48), from open markets and supermarkets were analyzed. Salmonella was found in 22 of 61 (36%) open market samples (48% of chicken, none of pork and beef, and 53% of shrimp) and in 12 of 75 (16%) samples from supermarkets (57%, 12%, 24%, 0% respectively). However, a small number of L. monocytogenes were isolated, where 6 of 217 (3%) were samples from open markets (6% of chicken and 3% of pork) and 17 of 171 (10%) were from supermarkets (3% of beef, 4% of chicken, and 32% of pork). In both markets, L. monocytogenes was not detected from shrimps, neither from oysters. E. coli O157, Shigella and tdh-positive V. parahaemolyticus were not isolated in this collection. Several Salmonella and L. monocytogenes isolates were multidrug-resistant. Both markets would need better assessment, since multidrug-resistant strains have been isolated and they may lead to therapeutic failure.