Cheeses Of Turkey Research Articles

Investigation of some probiotic properties of Lactobacillaceae strains isolated from traditional Tulum cheese in Turkey

The aim of this study was to evaluate the probiotic properties of Lactobacillaceae strains isolated from Tulum, Turkey. Ten strains of Lactobacillaceae spp. were taxonomically identified as follows: Lactiplantibacillus plantarum subsp. plantarum (6), Lacticaseibacillus paracasei (2), Lacticaseibacillus rhamnosus (1) and Lacticaseibacillus casei (1). Their probiotic properties, antimicrobial activities and tolerance to simulated gastrointestinal conditions such as low pH, pepsin, pancreatin and bile salts were evaluated. The results show that 10 lactic acid bacterial strains have high auto aggregation, coaggregation and hydrophobic properties. Antibiotic resistance and haemolytic activity were determined for safety assessment of the strains. Selected isolates showing high antimicrobial activity and the ability to remove cholesterol were also detected. These bacteria were found to have antioxidant activity as well. Therefore, these ten extracted lactic acid bacteria are promising potential candidates for use as probiotics. In this comprehensive study, L. plantarum SM27, L. plantarum S74 and L. paracasei RU39-7 were found to have the best probiotic properties. Important information was obtained on the probiotic and functional properties of Lactobacillaceae strains isolated from traditionally fermented Tulum cheese, which can be used as a rich source of probiotic bacteria. It was found that it is possible to isolate probiotic bacteria from traditional fermented cheeses.

The characterization of the non-starter lactic acid bacteria and yeast microbiota and the chemical and aromatic properties of traditionally produced Turkish White Cheese.

Turkish White Cheese is a brined (or pickled) cheese with a salty, acidic flavor and a soft or semi-hard texture. It is the most produced and consumed type of cheese in Turkey. The purpose of this study was to determine the non-starter lactic acid bacteria and yeast microbiota of traditionally produced Turkish White Cheese and analyze the chemical properties and the aroma profile of the cheese. The results of the study identified 27 distinct strains belonging to 14 the non-starter lactic acid bacteria species and 49 different strains belonging to 11 yeast species. Lactobacillus plantarum was found to be the dominant species among the lactic acid bacteria, while Candida zeylanoides was the dominant yeast species in the White Cheese samples. In addition, Kluyveromyces lactis and Debaryomyces hansenii were prominent yeast species in cheese samples. Turkish White Cheese samples had different aromatic properties. The study is highly significant as it anaylzed both non-starter lactic acid bacteria and yeast microbiota of traditionally produced Turkish White Cheese through molecular methods. It also determined and analyzed a number of chemical and aromatic properties of White Cheese.

Determination of safety status and probiotic properties ofEnterococcusstrains isolated from traditional cheeses in Turkey

This study aimed to evaluate the probiotic properties of Enterococcus strains isolated from Turkish traditional cheeses. Fifty-two Enterococcus spp. were taxonomically determined as follows: Enterococcus faecium (26), Enterococcus faecalis (18), Enterococcus durans (6), and Enterococcus italicus (2). The ability of isolates/strains to survive the harsh conditions (acidity and in-vitro gastric solution) of the gastrointestinal tract was established. They also showed auto-aggregation, hydrophobicity, and co-aggregation ability. Hydrophobicities of the strains were found between 0.8%-21%, 0.7%-56%, and 2%-63% for xylene, chloroform, and ethyl acetate, respectively. Autoaggregation values of the Enterococcus strains were 4%-20%, 7%-30%, and 36%-98% after 2, 4, and 24-h incubation, respectively. In this study, the Enterococcus strains tested showed co-aggregation ability with the Escherichia coli ATCC 25922, Salmonella Typhimurium ATCC 14028, and Staphylococcus aureus ATCC 25923. The results of PCR amplification revealed that only five strains possess virulence factor genes (gelE,asa1,cyl A,esp). We determined antibiotic resistance, biofilm forming abilities, and hemolytic activity for safety evaluation of strains. In this large and comprehensive study, we found that only few of Enterococcus strains have promising probiotic potential, among which E. faecalis ES1 and E. faecium EM1 showed the best probiotic properties (are the most promising probiotic candidates).

Some quality properties and volatile compound profile of Ardahan Tel cheese, a traditional cheese in Turkey

Some quality properties and volatile compound profile of Ardahan Tel cheese, a traditional cheese in Turkey

Detection of antibiotic resistance profiles and aminoglycoside-modifying enzyme (AME) genes in high-level aminoglycoside-resistant (HLAR) enterococci isolated from raw milk and traditional cheeses in Turkey.

The aim of this study was isolation and identification of the high-level aminoglycoside-resistant (HLAR) enterococci in raw milk and dairy products and to analyze their antibiotic resistance and the presence of aminoglycoside-modifying enzyme (AME) genes. A total of 59 HLAR enterococci were isolated from raw milk and traditional cheese samples. Thirty-nine of the 59 HLAR enterococci were isolated on streptomycin-containing agar medium, while the other 20 HLAR strains were isolated on gentamicin containing agar medium. The 59 HLAR enterococci were identified as 26 E. faecalis (44.07%), 18 E. faecium (30.51%), 13 E. durans (22.03%), and two E. gallinarum (3.39%) by species-specific PCR. Disk diffusion tests showed that teicoplanin were the most effective antibiotics used in this study, while 89.83% of isolates were found to be resistant to tetracycline. High rates of multiple antibiotic resistance were detected in HLAR isolates. Minimum inhibitory concentration (MIC) values of HLAR enterococci against streptomycin and gentamicin were found in the range of 64 to > 4096 µg/mL. Forty-seven (79.66%) of the 59 HLAR enterococci were found to be both high-level streptomycin-resistant (HLSR) and high-level gentamicin-resistant (HLGR) by MIC tests. However, no correlation was found between the results of the disk diffusion and MIC tests for gentamicin and streptomycin in some HLAR strains. The aph(3')-IIIa (94.92%) was found to be most prevalent AME gene followed by ant(4')-Ia (45.76%), ant(6')-Ia (20.34%) and aph(2'')-Ic (10.17%). None of the isolates contained the aac(6')-Ie-aph(2'')-Ia, aph(2'')-Ib or aph(2'')-Id genes. None of the AME-encoding genes were identified in E. durans RG20.1, E. faecalis RG22.4, or RG26.1. In conclusion, HLAR enterococci strains isolated in this study may act as reservoirs in the dissemination of antibiotic resistance genes.

The effect of some environmental conditions on planktonic growth and biofilm formation by some lactic acid bacteria isolated from a local cheese in Turkey.

The purpose of this study was to determine the effect of some environmental conditions (different temperature degrees and pH values, different salt, glucose and lactose concentrations) on the planktonic growth and biofilm formation ability of the lactic acid bacteria (LAB) isolated from a local cheese in Turkey. It was determined that Enterococcus lactis EC61 and Enterococcus faecalis EC41 are the most resistant bacteria to the changing environmental conditions and they can stably maintain their planktonic growth in the pH values of 6.5, 7.0, 7.5, and 8.0; in the salt concentrations of 4% and 6.5%; in the glucose concentration of 0.5%; and in the lactose concentrations of 0.5%, 1.5%, and 2.5%. It was found that all strains had the biofilm formation ability and especially the biofilm formation of Enterococcus lactis EC61 and Enterococcus faecalis EC41 strains significantly increased in the acidic pH values and in the increasing glucose and lactose concentrations, and significantly decreased in the increasing salt concentration. When considered in terms of LAB potential as a starter culture, specifying the effect of some environmental conditions on the planktonic growth and biofilm formation ability is important for the food industry. As a conclusion, it was determined that lactic acid bacteria, which were previously determined to have some starter culture characteristics, had additional properties on the way to being an starter culture.

Prevalence, characterization and antibiotic resistance of Staphylococcus aureus isolated from traditional cheeses in Turkey

ABSTRACT This study aimed to provide information about the characteristics of Staphylococcus aureus strains isolated from traditional Turkish cheese samples in Ankara (Turkey), focusing on their prevalence, phenotypic and genotypic characteristics, and antibiotic resistance. To this end, 387 cheese samples were randomly collected from various local bazaars and supermarkets. A total of 85 S. aureus isolates were identified by morphological, biochemical and molecular methods. In addition, the strains were screened for enterotoxin production. None of the strains was confirmed as being enterotoxigenic. The strains were tested for resistance to 29 different antimicrobial agents using the phenotyping agar diffusion method. The strains showed a high level of resistance (60–84.71%) to penicillin, ampicillin, and oxacillin. Furthermore, resistance to lincomycin, cefoxitin, clindamycin was also observed, although at slightly lower levels (50.59–57.65%). Additionally, low-level resistance (1.4–48.8%) was observed against gentamicin, methicillin, kanamycin, streptomycin, cefepime, erythromycin, teicoplanin, rifampicin, vancomycin, cefazolin, netilmicin, sulfadimethoxazole, ofloxacin, enrofloxacin, tetracycline, ciprofloxacin, azithromycin, trimethoprim, and norfloxacin. None of the strains was resistant to doxycycline, linezolid, furazolidone, and chloramphenicol. About 72.94% of S. aureus strains were resistant to multiple drugs. Our results suggest that the presence of a high level of multidrug-resistant S. aureus strains in traditional Turkish cheese is not safe for human consumption. Therefore, uncontrolled use of antibiotics should be prevented in veterinary medicine.

Impact of Cooking pH Values on the Textural and Chemical Properties for Processed Cheeses with/without the Use of Traditional Village Cheese during Storage

Processed cheeses (PCs) were made under varying cooking pH values (5.3, 5.4, 5.5, and 5.6) using a processed cheese cooker. Along with emulsifying salts (2.5%), distilled water, NaCl (2%) and a colouring agent under these cooking pH values, the PC samples made with either 100% fresh curd and rennet casein coded processed cheese control (PCC) as control or ~70% fresh curd-~30% traditional village cheese coded processed cheese with village cheese (PCv). The main aim of this study was to determine the effect of the varying cooking pH values on the textural properties for the PCv samples compared with the control sample during 90 days of storage. Chemical and textural properties of all PC samples were investigated over time. The chemical compositions of the PC samples (dry matter and ash) increased at d 90 of storage significantly, due to 1-d ripening of all PC samples at ambient temperature in terms of the manufacturing protocol of the cheese. The textural properties of the PC samples were altered by the varying cooking pH values. It may propose that the interactions of the proteins at the cooking pH values during processing and biochemical mechanisms in the cheese systems could likely affect the texture of the PC samples over time. Hardness, gumminess and chewiness values of all PC samples also increased over time (p<0.05). This study is also to give some knowledge on the design of PC manufacture to cheese makers, and a marketing opportunity to local cheese makers who individually make a traditional village cheese in Turkey.

BIOGENIC AMINE CONTENTS OF FRESH AND MATURE KASHAR CHEESES DURING REFRIGERATED STORAGE

Kashar is one of the most consumed traditional cheeses in Turkey. It is produced as fresh or mature, which differ in ripening periods. Safe consumption period of kashar was investigated during refrigerated storage. Five samples of fresh and five samples of mature kashar cheeses collected from local supermarkets in Turkey were analyzed. Changes in biogenic amines, pH and thiobarbituric acid reactive substance of fresh and mature kashar cheeses were investigated during storage. Mature kashar cheeses had higher biogenic amine concentrations than fresh kashar cheeses. During storage, total biogenic amine contents of all samples increased significantly (p<0.05). Total biogenic amine contents of mature kashar cheeses were higher than maximum allowed limit of 1000 mg/kg and can cause toxicity. It was found that fresh kashar cheeses were safer than mature kashar cheeses with respect to the toxic limits of biogenic amines.

Prevalence, characterization and antibiotic resistance of enterococci from traditional cheeses in Turkey

ABSTRACTThe aim of the present work is to provide information about Enterococcus strains isolated from traditional Turkish cheese samples in Ankara (Turkey), focusing on their prevalence, phenotypic and genotypic characteristics, and antibiotic resistance. A total of 213 probable enterococcal isolates isolated from 215 samples were identified by phenotypic and genotypic methods. As a result of 16S rDNA sequence analysis, 88 of the 213 enterococci strains were identified as Enterococcus faecium and 125 as Enterococcus faecalis. The E. faecalis strains (58.7%) were identified as the dominant species isolated from cheese samples in Turkey. The 213 Enterococcus strains were tested for susceptibility to 12 different antimicrobial agents. The resistance phenotype were as follow: nalidixic acid (100%), kanamycin (98.6%), rifampicin (78.4%), ampicillin (48.8%), ciprofloxacin (45.5%), erythromycin (18.8%), tetracycline (11.7%), penicillin G (5.6%), chloramphenicol (4.2%), gentamycin (3.8%) and streptomycin (1.4%). None of the strains was resistant to vancomycin. E. faecium strains showed more resistant phenotypes than E. faecalis strains as shown by the antibiotic resistance levels. It was also observed that the resistance of E. faecium and E. faecalis strains against the antibiotics was statistically significant (p ˂ 0.05). In total, 100% of E. faecium and 88.8% of E. faecalis strains were resistant to multiple drugs.

A View on Volatile Compounds of Kars Gruyere Cheese, a Traditional Cheese in Turkey

The study aims to determine volatile compound profile of Kars Gruyere cheese, which was produced by the traditional method. The volatile components were extracted from samples obtained from 20 different sales points, by using the SPME (solid phase micro-extraction) technique and identified using Gas Chromatography/ Mass Spectrometer (GC/MS). In the samples, totally 40 compounds were identified including aldehydes, ketones, alcohols, acids, esters, terpenes, aliphatic hydrocarbons, aromatic hydrocarbons, nitrogenous compounds and furan group. The study determined that the compounds of acetaldehyde, nonanal, 2-pentanone, ethanol, acetic acid, propionic acid, butanoic acid, ethyl propionate, ethyl butyrate, n-buthyl acetate, toluene and 6-methylthio-(1)-benzothiazole compounds have a significant share in the volatile compound porfile of Gruyere cheese’s.

Türkiye’de Geleneksel Yöntemlerle Üretilen Peynirlerin Küf Florası

In our country, there are many cheese types that are produced traditionally. Cheeses which produced from cows, sheep and goat milk that matured with spontaneous growth of molds present in livestock skins, pots and similar environments are among them. They are produced traditionally in Mediterrian, Central and Eastern Anatolia regions. Molds that grow spontaneously in cheeses could create public health risk because of their secondary metabolites. Penicillium spp. are the most isolated mold from these cheeses and Penicillium roqueforti is determined as the dominant species. Furthermore, Aspergillus, Alternaria, Mucor, Geotrichum, Cladosporium species have been isolated. It is very important to control the ripening conditions and starter strain selection since some strains were reported as mycotoxin producers. In this review, it has been tried to give general information about traditional production of mold-ripened cheese in Turkey and the mold flora found in traditional cheeses. In addition, public health risk of these cheeses is reported.

Characterisation of Phenotypic and Genotypic Antibiotic Resistance Profile of Enterococci from Cheeses in Turkey.

The aim of this study was to determine the prevalence of enterococci in cheese samples and to characterize their antimicrobial resistance profiles as well as the associated resistance genes. A total of 139 enterococci were isolated from 99 cheese samples, the isolates were identified as E. faecalis (61.2%), E. faecium (15.1%), E. gallinarum (12.9%), E. durans (5.0%), E. casseliflavis (2.9%) and E. avium (2.9%). The most frequent antimicrobial resistance observed in enterococci isolates was to lincomycin (88.5%), followed by kanamycin (84.2%), gentamycin (low level, 51.1%), rifampin (46.8%) and tetracycline (33.8%). Among the isolates, the frequencies of high level gentamycin and streptomycin resistant enterococci strains were 2.2% and 5.8%, respectively. Apart from the mentioned antibiotics, low levels of resistance to ciprofloxacin, erythromycin and chloramphenicol were found. Moreover no resistance was observed against penicillin and ampicillin. The antimicrobial resistance genes including tetM, tetL, ermB, cat, aph(3’)-IIIa, ant(6)-Ia and aac(6’)-Ieaph(2”)-Ia were found in enterococci from Turkish cheese samples. In the current study, we provided data for antibiotic resistance and the occurrence of resistance genes among enterococci. Regulatory and quality control programs for milk and other dairy products from farms to retail outlets has to be established and strengthened to monitor trends in antimicrobial resistance among emerging food borne pathogens in Turkey.

Incidence of antibiotic resistance and virulence determinants in Enterococcus faecium and Enterococcus faecalis strains, isolated from traditional cheeses in Turkey

Enterococcus faecalis (n = 15) and Enterococcus faecium (n = 33) strains isolated from traditional Turkish cheeses were tested for susceptibility to 11 different antimicrobial agents and for the presence of selected genes encoding resistance and 13 genes encoding virulence factors using PCR. Furthermore, the plasmid profile of enterococci was examined. All E. faecium and E. faecalis isolates were resistant to nalidixic acid and kanamycin. The percentages of other resistant E. faecium and E. faecalis isolates, respectively, were 97 and 100% to streptomycin, 15.1 and 20% to ampicillin, 9.1 and 26.7% to gentamycin, 12.1 and 46.6% to chloramphenicol, 12.1 and 60% to tetracycline, 75.7 and 93.3% to rifampicin, 84.8 and 80% to vancomycin, 97 and 100% to erytromycin and 72.7 and 60% to ciprofloxacin. efaA fm (100%) and ccf (90.1%) genes were the most common virulence genes identified among E. faecium isolates while efaA fs (100%), cpd (100%), ccf (93.3%) and cob (86.7%) genes among E. faecalis isolates. Cytolysin determinants (cylM, cylB, cylA) were not detected among tested strains. Plasmid profile analysis of Enterococcus spp. revealed plasmid DNA bands ranging in size from 2.4 to 35.8 kb.

Microbiological quality of artisanal Sepet cheese

Microbial diversity in milk and in cheese itself affects the biochemical and sensory characteristics of artisanal cheeses. In this study, the microflora of Sepet cheese, which is a traditional artisanal cheese in Turkey, was investigated. Average lactococci, lactobacilli, enterococci, yeast, mould, coliform, psychrotrophic and total aerobic bacteria, presumptive Staphylococcus aureus counts were; 7.31 ± 1.08, 7.19 ± 1.02, 6.84 ± 0.92, 3.19 ± 1.40, 0.84 ± 0.89, 2.18 ± 1.81, 4.92 ± 1.15, 7.53 ± 1.13 and 1.25 ± 1.70 log cfu/g, respectively. Staphylococci, coliform and mould counts were less than 1.00 log cfu/g at the end of ripening, which was at around 6–8 °C for 3 months. According to phenotypic and genotypic identifications, isolates were closely related to Lactobacillus plantarum, Weisella confusa, Weisella paramesenteroides, Pediococcus pentasaceous, Enterococcus casseliflavus, Enterococcus durans and Enterococcus faceium. This study provides baseline data on the microflora of traditional artisanal Sepet cheese, which is a prerequisite for a successful scale up to industrial production.

Survival of Listeria monocytogenes during Production and ripening of traditional Turkish Savak tulum cheese and in synthetic gastric fluid.

This study investigated the survival and acid tolerance of Listeria monocytogenes during the 2-day processing stage and 90-day ripening of Savak tulum cheese, a traditional cheese in Turkey. Experimental Savak tulum cheese was produced from raw sheep's milk that was inoculated with a L. monocytogenes mixture consisting of five strains (average 7.0 log CFU/ml) and was ripened at 6°C for 90 days. Microbiological and chemical analyses and acid exposure experiments in synthetic gastric fluid (SGF) (pH 1.5 to 2.5) were carried out on days 1 and 2 during processing and on days 0, 15, 30, 45, 60, and 90 during ripening. The numbers of L. monocytogenes did not decrease during processing, but a total of 4.1 log CFU/g reduction was observed during ripening. Throughout the ripening period, L. monocytogenes cells survived direct 90-min exposures of the cheese samples to SGF. These results suggest that, although the pathogen numbers decreased in Savak tulum cheese ripened at 6°C for 90 days, a sublethal environment may have occurred in the cheese during the production stage, activating the acid-tolerance mechanisms of the pathogen and allowing L. monocytogenes to maintain its viability in the SGF for 90 min.

Occurrence of Aflatoxin M1 in Vacuum Packed Kashar Cheeses in Turkey

In this study, aflatoxin M1 (AFM1) levels of vacuum packed Kashar cheese marketed in the Black Sea Region of Turkey were determined during October 2008 and June 2009. The occurrence of AFM1 contamination in vacuum packed cheese samples was investigated using immunoaffinity column extraction and high-performance liquid chromatography. AFM1 was detected in 144 (97.96%) of cheese samples ranging from 0.015 to 3.774 μg/kg cheese, and mean value of AFM1 was found to be 0.273 μg/kg cheese. AFM1 level in 16 (11.11%) of positive samples was higher than the maximum tolerance limit (0.5 μg/kg) accepted by Turkish Food Codex.

Isolation and characterization of yeasts associated with Turkish-style homemade dairy products and their potential as starter cultures

In this research, 56 yeast strains were isolated from different homemade dairy products in Turkey. Traditional and genotypic methods were used for the characterization of the yeast strains. Debaryomyces hansenii (82%) was the dominant species in all the studied samples and only this species was found in at least one sample from all the studied samples. The other isolates belonged to the species Candida haemulonii, Candida membranifaciens, Candida tropicalis, Candida zeylanoides, Kluyveromyves marxianus,Pichia anomala and Pichia guilliermondii. In the present study, the following properties were studied: lipolytic and proteolytic activities, the ability to grow at different temperatures, different values of pH, different concentrations of salt, and to assimilate and or ferment compounds like citrate, galactose, glucose, lactate, lactose. In conclusion, we found that TEM 16 and TEM 17 strains identifed as D. hansenii in this study have the potential to be used in the production of cheese in Turkey. Key words: Debaryomyces hansenii, dairy products, yeast, ITS-RFLP, technological characteristics

Purification and partial characterization of bacteriocin produced by Lactococcus lactis ssp. lactis LL171

Lactic acid bacteria (LAB) are possessing ability to synthesize antimicrobial compounds (like bacteriocin) during their growth. In this regard, novel bacteriocin compound secreting capability of LAB isolated from Tulum Cheese in Turkey was demonstrated. The synthesized bacteriocin was purified by ammonium sulphate precipitation, dialysis and gel filtration. The molecular weight (≈3.4 kDa) of obtained bacteriocin was confirmed by SDS-PAGE, which revealed single peptide band. Molecular identification of LAB strain isolated from Tulum Cheese was conducted using 16S rDNA gene sequencing as Lactococcus lactis ssp. lactis LL171. The amino acid sequences (KKIDTRTGKTMEKTEKKIELSLKNMKTAT) of the bacteriocin from Lactococcus lactis ssp. lactis LL171 was found unique and novel than reported bacteriocins. Further, the bacteriocin was possessed the thermostable property and active at wide range of pH values from 1 to 11. Thus, bacteriocin reported in this study has the potential applications property as food preservative agent.

High-Performance Liquid Chromatography Analysis and Assessment of Benzoic Acid in Yogurt, Ayran, and Cheese in Turkey

Among food sources, particular attention is paid to milk and dairy products, due to its nutritional importance. Benzoic acid is extensively used in the preservation of foods. A reliable method for the determination of benzoic acid in some dairy products, such as yogurt, ayran, and cheese using high-performance liquid chromatography and UV detection was validated. The peak of benzoic acid was measured at a wavelenght of 226 nm. Samples were purchased from supermarkets in Turkey in the period 2009–2010. All dairy product samples were produced from cow’s milk. The levels of benzoic acid in cheese, yogurt, and ayran samples were in the range of 3.17 to 56.77 mg kg−1, 8.94 to 28.30 mg kg−1, and 1.54 to 16.57 mg L−1, respectively. The results show that benzoic acid widely occurs in milk products in Turkey at the low levels.