Identification and Isolation of the Yeasts in Traditional Yogurts Collected From Villages in Gaziantep,Turkey

ranged from 3.9-6.0. After yeast isolation from the yogurts that 25 samples were showed including yeast, the total number of their ranged from 1-1.8 x 10 8 CFU/g on MRS agar. MALDI TOF MS was used for yeast identification. Among the isolates, 52% were Candida kefyr , 36% were Saccharomyces cerevisiae , 8% were Candida tropicalis and 4% Candida lypolitica . These results showed that traditional yogurts collected from villages in Gaziantep Province contain various contamined yeast; they are detrimental for human healthy on yogurt production. abstract


Introduction
During the fermentation of foodstuffs, the main physical and chemical changes occur due to the growth and fermentative activity of the LAB that are used as starter cultures. LAB are used as starter cultures for the fermentation of milk [1]. Yogurt is a milk product that is obtained by the bacterial fermentation of milk. Lactic acid is produced via the fermentation of milk sugar, also known as lactose. Lactic acid is the substance that confers the typical textural and sensory characteristics of yogurt and acts on milk protein [2].
Besides low asid is a suitable environment for the life of yeasts.
Fermented products also contain yeasts. They have created positive effects on the bacteria via P H changing and biological substances releasing [3]. If a matter of caution is to be taken, they may be causing of the spoilage in fermented product.
Yogurt contains high concentrations of LAB and the smaller yeast have several potential health benefits and probiotic potential; it can increase lactose tolerance, balance the intestinal microflora, act as an antimicrobial, stimulate the immune system, induce antitumor effects, and induce anti-cholesterolemic effects. Yeast may be some aroma components and interact with LAB that are primer starter cultures. Yeast growth stabilizes LAB which are starter culture [4]. Knowledge of the biochemical properties of the starter cultures is necessary to determine the final characteristics of the fermented food product, such as its acidity, aroma and flavor. To gain such knowledge, it is crucial to identify and characterize the yeast in a starter culture. The aim of this study was to identify of the yeast that could be isolated from traditional yogurts collected from villages in Gaziantep Province. Additionally, preliminary information was prepared to create reliable yogurt in respect to pathogen microorganisms.

Isolation and Total Yeast Counts
The samples were diluted before culturing on MRS (de Man, Rogosa and Sharpe) agar (Oxoid, England). The MRS plates were incubated for 3 days in aerobic environments at 30°C [5][6][7]. All of the suspect colonies in petri dishes were recorded as CFU/g [6].

Results
According to the results of this study, the pH values of 208 yogurt samples ranged from 3.9 to 6.0. The average P H of the yogurts ranged between 4.30 and 5.14 as seen  Figure 1.

Discussion
The present study is the first to specifically analyze the yogurt mycoflora in Gaziantep Province. In this study, the results showed it has been showed that the P H values of yogurts obtained from villages in Nigeria were between 3.80 and 4.48 [11]. Additionally, they reported that these levels were lower than the P H levels of commercial yogurts. Yeast isolation studies were carried out from fermented milk products in several countries. C. tropicalis has been isolated from Tanzania fermented milk. But, the same yeast species has not isolated from yogurt samples.
Researches said that yeast contamination has been prevented and controlled is importance on fermented dairy producing [12].
Kavas et al. [4] have isolated these yeast species from isolated from İzmir, Turkey [4]. Saccharomyces cerevisiae have isolated from Nigeria yogurt samples, this rate was 36% in present study [13]. Saccharomyces may be related to suitable flavor development and Candida spp.
yeasts that have got protease activity would long shelf life of milk products, also enhancing activation in LAB fermentation [12]. The Candida species were the predominant among 25 yeasts species including 16 Candida (64%) and 9 Saccharomyces (36%).
In this study, Candida kefyr, Candida lypolitica, Saccharomyces cerevisiae isolated from traditional yogurts were also isolated from traditional fermented camel milk in a previous study [3]. The present study has showed that yogurt fermented dairy food comprise yeast microflora. Yeasts interact with other microorganisms [12] and yeasts are consist secondary flora in fermented milk products [14] isolated sixteen species belonging to Candida and Saccharomyces genus from Pakistan yogurt samples. But these yeast species are out of our isolated yeast species [15]. Biberoglu and Ceylan (2013) found as 50% Candida kefyr,23.95% Saccharomyces cerevisiae, 4% Candida lypolitica same results with our present study from yogurt samples of Erzurum and Kars regions, Turkey [14]. Soulides (1956) isolated lactose fermented Torulacremoris from yogurt. New name of this species in binominal named is Candida pseudotropicalis [16].
We isolated several Candida species in too, in present study.
Moreira et al. [17] found 19% Saccharomyces cerevisiae rate from Brazil yogurts [17]. This rate was 36% in traditional yogurt samples, Gaziantep, Turkey in our study. Saccharomyces cerevisiae and Candida spp. which are contained yeasts causing spoilage in traditional yogurt production, were isolated in this study. However, the yeast species that we isolated have previously been demonstrated to have the potential harmful ability to produce yogurt. These species may represent factors that is to be need underlie hygiene properties of traditional yogurts. These contaminants must be struggled. In a sense important results have been obtained for the provision of traditional yogurts to consumers in our city. This study may represent a fundamental investigation for eliminated contained yeasts during the yogurt production process, as isolated bacterial species that have previously been isolated in other studies.
The four different kinds yeast of in these yogurts samples have been isolated in this study. In the data obtained is a preliminary study and firstly study in this region which will be useful information to another region for this non-commercial yogurt.

Conclusion
Our study researches the basic development of suitable hygiene conditions for traditional yogurt production. So far, there has been little specific research on yogurt contained microflora in Turkey.
Our study is the first to specifically analyze the yogurt contaminants in Gaziantep Province, Turkey.