Browsing by Author "Karagözlü, C"

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    Survival characteristics of E-coli O157:H7, S-typhimurium and S-aureus during kefir fermentation
    Karagözlü, N; Karagözlü, C; Ergönül, B
    In this research, the growth and survival of E. coli O157:H7, Salmonella typhimurium and Staphylococcus aureus were investigated during kefir fermentation. Two different levels of inoculation of the strains were conducted; the levels of 10(2) CFU/ml (EC-1, SA-1 and S-1) and 10(3) CFU/ml (EC-2, SA-2 and S-2). At 0, 2, 6, 12, and 24 hours of kefir fermentation at 23 +/- 1 degrees C, samples were taken and the counts of E. coli O157:H7, S. typhimurium, and S. aureus were determined. EC-1 grew from 2.29 +/- 0.02 log CFU/ml to 4.13 +/- 0.18 log CFU/ml whereas EC-2 grew from 3.22 +/- 0.04 log CFU/ml to 6.78 +/- 0.99 log CFU/ml. Both S-1 and S-2 viable populations grew during the fermentation period, where sample S-1 grew from 2.37 +/- 0.20 log CFU/ml to 4.64 +/- 0.67 log CFU/ml and sample S-2 grew from 3.52 +/- 0.07 log CFU/ml to 5.60 +/- 0.10 log CFU/ml. SA-2 strains grew from 3.06 log CFU/ml to 3.64 log CFU/ml, SA-1 strains grew from 2.28 log CFU/ml to 2.66 log CFU/ml. According to the findings, E. coli O157:H7, S. typhimurium, and S. aureus can survive in kefir during fermentation.
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    Utilization of pomegranate and black grape seed by-products in yogurt production: Effects on phenolic compounds and antioxidant activity
    Çaliskanlar, S; Saygili, D; Karagzölü, N; Karagözlü, C
    The present study investigated the potential utilization of pomegranate and black grape seed by-products of the food industry in yogurt production. Specifically, we examined the effect of polyphenols on antioxidants in yogurts produced using two different starter cultures: classical yogurt culture (Lactobacillus delbrueckii subsp. bulgaricus + Streptococcus thermophilus) and yogurt culture supplemented with L. casei. Various parameters, including pH, acidity, viscosity, fat content, protein content, dry matter content, color, microbiological properties, and sensory attributes, were analyzed in the yogurt products. The present findings indicate that incorporating pomegranate and grape seed powder and using different starter cultures significantly affected the yogurt's phenolic content and antioxidant activity. Furthermore, we observed decreased phenolic content and antioxidant activity during the 21-day storage period. Interestingly, yogurts produced with pomegranate seed powder and L. casei culture exhibited higher antioxidant activity than the other samples. Importantly, none of the yogurts containing pomegranate and grape seed powders had microbial counts below 107 cfu/g for L. delbrueckii subsp. bulgaricus, S. thermophilus, and L. casei, indicating no adverse effects on probiotic properties. Sensory evaluation revealed that the yogurt product prepared with grape seed powder and a combination of yogurt culture (L. delbrueckii subsp. bulgaricus + Streptococcus thermophilus) and L. casei was particularly well-received. In conclusion, the functional properties of grape seed powder and pomegranate seed powder make them suitable natural ingredients for enhancing the antioxidant activity of yogurt. The study highlights the potential of utilizing these by-products to develop yogurt products with added health benefits. The search for consuming healthy products is increasing day by day and it is inevitable for consumers to turn to functional products with health-supporting features. The enrichment of yogurt, which is a traditional product, with pomegranate and black grape seeds with high antioxidant capacity improves both the sensory properties of the final product and increases the health-supporting quality of the final product.image
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    Physicochemical and Sensory Characteristics of Winter Yoghurt Produced from Mixtures of Cow's and Goat's Milk
    Kesenkas, H; Karagözlü, C; Yerlikaya, O; Özer, E; Akpinar, A; Akbulut, N
    Winter yoghurt is one of the most popular dairy products in Van and Hatay region of Turkey. It is made of different kinds of milk, and known as cooked yoghurt or salted yoghurt due to its high solids content and long shelf life. In this study, two different concentration methods were used to produce traditional winter yoghurt. Some physical (firmness and cohesiveness, L-, a- and b- values), chemical (total solid, fat, protein, pH, lactic acid, salt) and sensory analyses (color, odor, consistent and flavor) were made to determine the effect of production methods and storage on winter yoghurt samples at the 1st, 30th, 60th and 90th days. Significant differences were found between sensory, rheological properties and color values of winter yoghurts however no significant differences were found between physicochemical properties of the samples. Especially, winter yoghurts produced from 100% goat milk were the more appreciated samples.