Mehmet Karapinar

Inhibition of foodborne pathogens by thymol, eugenol, menthol and anethole

Abstract The antibacterial effects of four spice components, namely thymol, eugenol, menthol and anethole were tested against Salmonella typhimurium, Staphylococcus aureus and Vibrio parahaemolyticus. Of the spice components tested, eugenol was found to be the most effective followed by thymol, anethole and menthol.

Microflora of Boza, a traditional fermented Turkish beverage

Boza, a Turkish traditional beverage made by yeast and lactic acid fermentation of cooked maize, wheat and rice flours was prepared and the microbial characteristics were investigated. During the course of fermentation from 0 to 24 h, populations of lactic acid bacteria and yeast raised from 7.6 x 10(6) and 2.25 x 10(5) after inoculation to 4.6 x 10(8) and 8.1 x 10(6), respectively; pH dropped from 6.1 to 3.5; total titratable acidity by means of lactic acid increased from 0.02 to 0.27 mmol/g; alcohol content increased from 0.017% to 0.79%. Seventy seven isolates of lactic acid bacteria and 70 yeast isolates were identified. The lactic acid bacteria isolated during the fermentation included Leuconostoc paramesenteroides (25.6%), Lactobacillus sanfrancisco (21.9%), Leuconostoc mesenteroides subsp. mesenteroides (18.6%), Lactobacillus coryniformis (9.1%), L. confusus (7.8%), Leuconostoc mesenteroides subsp. dextranicum (7.3%), Lactobacillus fermentum (6.5%), Leuconostoc oenos (3.7%). The yeasts isolated comprised Saccharomyces uvarum (83.0%) and S. cerevisiae (17.0%).

Inhibitory effects of anethole and eugenol on the growth and toxin production of Aspergillus parasiticus

The antifungal and antiaflatoxigenic activity of anethole and eugenol which are active components of commonly used spices was studied against two strains of Aspergillus parasiticus. Anethole, up to concentration of 400 micrograms/ml where complete inhibition was observed, delayed growth and reduced mycelial weight but it showed a stimulative effect on the toxin production of both strains. At a concentration of 300 micrograms/ml, eugenol inhibited the growth of both strains; levels of eugenol below 200 micrograms/ml enhanced production of aflatoxin particularly by A. parasiticus NRRL 299.

Sensitivity of some common food-poisoning bacteria to thyme, mint and bay leaves

Abstract The inhibitory effects of various concentrations of thyme, mint, bay leaves and their alcohol extracts were tested on the growth of three food poisoning bacteria, Salmonella typhimurium, Staphylococcus aureus and Vibrio parahaemolyticus . In each spice medium, S. typhimurium displayed the lowest sensitivity Thyme, which inhibited the growth of S. aureus at a level of 0.05% was the most inhibitory of the three spices studied. Bay leaves were found to be the least active spice of which 0.5% concentration was necessary for the growth inhibition of S. aureus . In each growth medium containing spice extracts, V. parahaemolyticus was found to be the most sensitive bacteria; growth was inhibited by the addition of 1000, 5000 and 6000 ppm of thyme, bay leaves and mint, respectively.

Removal of Yersinia enterocolitica from fresh parsley by washing with acetic acid or vinegar

Different washing procedures and solutions were applied to fresh parsley and the effect on artificially contaminated Y. enterocolitica and the natural population of aerobic bacteria was determined. Dipping the parsley containing 10(7) Y. enterocolitica per gram into the 2% (v/v) acetic acid or 40% (v/v) vinegar solutions for 15 min exerted pronounced bactericidal effect against this organism. No viable aerobic bacteria were recovered after 30 min dip in 5% (v/v) acetic acid, whereas vinegar led to 3-6 log10 cycles decrease in the number of aerobic bacteria depending on vinegar concentration and holding time.

Identification of lactic acid bacteria isolated from Tarhana, a traditional Turkish fermented food.

Tarhana is a traditional fermented product produced from a mixture of spontaneously fermented yogurt and wheat flour in Turkey. The aims of the present study were to enumerate and identify for the first time by molecular biology-based methods predominant lactic acid bacteria (LAB) isolated during processing of Tarhana. Samples were collected from eight different regions of Turkey. In order to explore the relationship between raw material and the microbiology of Tarhana, yogurt and wheat flour were also analyzed. A total of 226 Gram-positive and catalase-negative isolates were obtained from MRS, M17 and SBM (Slanetz and Bartley Medium). The isolates were grouped and identified using a combination of pheno- and genotypic methods including rep-PCR fingerprinting [(GTG)(5) primer], multiplex PCR, 16S rRNA gene sequencing and carbohydrate assimilation profiling. Pediococcus acidilactici were found to constitute 27% of the isolates, 19% were identified as Streptococcus thermophilus, 19% as Lactobacillus fermentum, 12% as Enterococcus faecium, 7% as Pediococcus pentosaceus, 5% as Leuconostoc pseudomesenteroides, 4% as Weissella cibaria, 2% as Lactobacillus plantarum, 2% as Lactobacillus delbrueckii spp. bulgaricus, 2% as Leuconostoc citreum, 1% as Lactobacillus paraplantarum and 0.5% as Lactobacillus casei. The different production sites investigated all had individual LAB profiles, but with P. acidilactici and S. thermophilus being isolated from the majority of samples. The main source of P. acidilactici and S. thermophilus was found to be the yogurt.

Effects of sodium bicarbonate, vinegar, acetic and citric acids on growth and survival of Yersinia enterocolitica

The effects of sodium bicarbonate, vinegar, acetic and citric acids on growth and survival of Yersinia enterocolitica in a laboratory medium were investigated. Acetic acid was found to be the most effective agent used, which completely inhibited the growth of the test organism at concentration of 0.156% (v/v) in the media incubated at 22 degrees C for 48 h. The antimicrobial activity of acetic acid and vinegar on the survival of the test bacterium in media incubated at 22 degrees C for 60 min was dependent on the inocula levels.

Efficacy of myrtle oil against Salmonella Typhimurium on fresh produce

The antimicrobial activity of myrtle leaves (Myrtus communis) oil was tested against the nalidixic acid resistant strain of Salmonella Typhimurium ATCC 13311. An inoculum (100 microl, ca.10(8) cfu/ml) was deposited on the skin of whole tomatoes and 10 g of shredded iceberg lettuce, dried for 2 h at 22 degrees C and held for 22 h at 4 degrees C before treatments. Inoculated iceberg lettuce (3.51-3.99 log cfu/g) and tomatoes (3.47-4.86 log cfu/tomato) were treated with three different washing procedures for 5, 10, 15 and 20 min; washing with sterile distilled water (control), washing with three different concentrations of myrtle leaves oil and the last treatment was a combination of washing with myrtle leaves oil and then rinsing in sterile distilled water for 1 min. Washing with myrtle leaves oil with or without rinsing procedures caused significant reduction in S. Typhimurium population compared with the control after treatment for four different times (p<0.05). There is no significant difference between washing times in reduction of S. Typhimurium (p>0.05). The maximum logarithmic reductions of 1.66 cfu/g-1.89 cfu/tomato were respectively obtained on iceberg lettuce and tomatoes treated with 1000 ppm myrtle leaves oil without any rinsing treatment. The results suggest that the use of myrtle leaves oil is an innovative and useful tool as an alternative to the use of chlorine or other synthetic disinfectants in fruits and vegetables, especially for organic products.

Efficacy of sumac and oregano in the inactivation of Salmonella Typhimurium on tomatoes

The antimicrobial efficacy of sumac (Rhus coriaria L.) water extracts (1%, 3% and 4%) and oregano (Oreganum onites) oil suspensions (25 ppm, 75 ppm and 100 ppm) was tested against the nalidixic acid resistant strain of Salmonella Typhimurium ATCC 13311 inoculated to tomatoes. The inoculated tomatoes (2.71-4.35 log cfu/tomato) were subjected to treatment for 5, 10, 15 and 20 min by washing with sterile distilled water (control), sumac extracts or oregano oil suspensions with or without rinsing in sterile distilled water. Treatment of tomatoes with sumac and oregano caused significant reductions in S. Typhimurium population compared to the control (P<0.05). However, there was no significant difference between washing times in the reduction of S. Typhimurium (P>0.05). The maximum logarithmic reductions of S. Typhimurium were obtained at levels of 2.38 and 2.78 logarithmic units on tomatoes treated with 4% sumac extract and 100 ppm oregano, respectively. No statistical difference was obtained in the number of S. Typhimurium recovered in different concentrations of treatment solutions in four different treatment times (P>0.05). The results suggest that the use of sumac water extract or oregano oil suspensions can be used to enhance microbial safety of tomatoes without loss in quality attributes.

The effects of citrus oils and some spices on growth and aflatoxin production by Aspergillus parasiticus NRRL 2999

Abstract The inhibitory effect of various concentrations of mint, sage, bay leaves, thyme, aniseed, red pepper and citrus peel oils on the growth of an aflatoxin-producing strain of Aspergillus parasiticus and its production of aflatoxin was studied. Amongst the herbs used, thyme was found a highly effective antifungal agent. Growth and aflatoxin formation was depressed by orange and lemon oils at a concentration of 1.6% through 10 days incubation.