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Öğe Chemical changes in strained dairy product produced with organic milk by using kefir grains and yogurt culture during refrigerated storage(Sidas Medya Ajans Tanıtım Danışmanlık Ltd. Şti., 2019) Güler, Zehra; Tekin, Ali; Dursun, AhmetThe objective of this study was to produce a strained dairy product made from organic milk using yogurt culture and kefir grains as a new product development. Strained dairy product was analyzed for carbohydrates, organic acids, volatile organic compounds (VOCs), basic chemical composition as well as overall acceptability at 1, 7, 14, 21 and 28 days of refrigerated storage. While galactose content in dairy products increased, lactose and glucose contents decreased on 14th day of storage. The main VOC was ethanol, accounted for about 58% of total volatiles. An increase in succinic acid (from 312 mg/kg to 638 mg/kg), acetic acid (632 mg/kg-843 mg/kg), ethyl octanoate (1.07%-4.15%) and a decrease in viscosity (5754 mPas-1050 mPas) and total solids (24.33%-20.64%) towards the end of storage were observed. Refrigerated storage for more than 21 days could not be recommended since the product was found unacceptable by the panelists but the product consumption at the first 21 days of storage may be an advantage for lactose intolerance humans due to its low lactose level.Öğe The effect of ripening medium (goat skin bag or plastic barrel) on the volatile profile, color parameter and sensory characteristics of Tulum cheese(Univ Zagreb, Fac Agriculture, 2021) Tekin, Ali; Guler, ZehraThe objective of this study was to determine volatile compounds, color parameters and sensory characteristics in raw sheep milk cheeses ripened up to 270 days using different packaging materials such as goat's skin bag or plastic barrel. Volatile compounds extracted by solid-phase microextraction were separated, identified and quantified using a gas chromatography (GC)-mass spectrometry detector (MS). Butanoic acid, hexanoic acid, octanoic acid, ethanol, ethyl acetate, ethyl butanoate, ethyl hexanoate, 2-butanol, 2-butanone and 2-heptanone were the predominant compounds in the volatile fraction of the cheeses. Among these, ethanol was the most abundant at the first 180 days of cheese ripening but there were 2-butanol and 2-butanone for cheese in plastic barrel (PB) and 2-heptanone for cheese in goat's skin bag (GS) at the 270 days. To best acknowledge, m-cimene, alpha-cubebene, trans-caryophylene, delta-cadinene and 16-oxasalutaridine were identified for the first time in sheep milk and its cheese. Discriminant analysis based on volatile compounds classified the cheeses according to their ripening times and also packaging materials. At the end of the ripening the differentiation between GS and PB cheeses was more evident. The results showed that GS cheese was more preferred by panelists. Cheeses ripened for more 180 days, in particular PB cheese, were much less acceptable to panelists. Therefore, in terms of optimum overall acceptability, 90 and 180 days ripening periods could be advised for the producers for PB and GS cheeses, respectively.Öğe Glycolysis, lipolysis and proteolysis in raw sheep milk Tulum cheese during production and ripening: Effect of ripening materials(Elsevier Sci Ltd, 2019) Tekin, Ali; Guler, ZehraIn this study, variations in basic chemical constitutes, organic acids (OAs), free amino acids (FAAs) and free fatty acids (FFAs) during ripening of raw sheep's milk Tulum cheeses in goat's skin bag (GST) or plastic barrel (PBT) were investigated. Ripening in goat's skin caused the differences in chemical compositions of Tulum cheese. Moisture loss, salt-in-moisture, fat and protein contents increased. No residual lactose was observed after 90 day. Lactic acid was principal organic acid, followed by propionic acid, acetic acid, formic acid, succinic acid and citric acid. The majority of amino acids were composed of Val, Pro, Tyr, Met, Leu, Trp, Phe, Lys and Glu. Hexadecanoic acid was the most abundant free fatty acid in the cheeses, which followed by cis-9-octadecenoic, octadecanoic, tetradecanoic, decanoic and trans-9-octadecenoic acids. The levels of total FFA and total OA were higher in GST-cheese in comparison to PBT-cheese but total FAAs were lower.Öğe Hydrogen incorporation into butter improves its microbial and chemical stability, biogenic amine safety, quality attributes, and shelf-life(Elsevier, 2024) Alwazeer, Duried; Bulut, Menekse; Ceylan, Mehmet Murat; Celebi, Yasemin; Kavrut, Enes; Cetintas, Yunus; Tekin, AliButter is susceptible to chemical and biological degradation. Hydrogen (H2) and nitrogen (N2) gases and BHT were incorporated into the butter, packaged into polyethylene laminated aluminum bags, and stored at 4 degrees C for 90 days. The microbial counts, peroxide value (PV), titratable acidity (TA), acidity degree value (ADV), and conjugated dienes and trienes (CD and CT) were examined. The samples' color and biogenic amines, amino acids, and volatile profiles were analyzed. At the end of storage, microorganisms grew slower in the H2 samples than in the other groups. The highest values of fat deterioration were determined for the control, while the lowest values were for the H2- and BHT-incorporated samples. All biogenic amines (BAs) showed the highest values in the control, while the lowest ones were observed in the BHT samples, followed by H2 and N2. H2 incorporation into butter limited the spoilage microorganism growth, improved the color, restricted the formation of BAs (44-61%), increased the levels of some amino acids (Met and Lys), and didn't give an off-flavor. The physicochemical results showed that H2 extended the shelf life of butter by 30 days. H2 incorporation can help the dairy industry extend shelf life and maintain the product's quality and safety.Öğe Keçi derisi ve bidonda olgunlaştırılan koyun (Karaman) tulum peynirlerinde biyokimyasal ve duyusal nitelikler(Hatay Mustafa Kemal Üniversitesi, 2016) Tekin, Ali; Güler, ZehraÇalışmada, tulum peyniri üretimi starter kültür kullanılmadan Akkaraman çiğ koyun sütü kullanılarak gerçekleştirilmiştir. Tulum peynirleri 270 gün boyunca keçi derisi ve bidon ambalajlarda olgunlaştırılmıştır. Olgunlaşma süresi ve ambalaj materyalinin tulum peynirlerinin genel kimyasal kompozisyonu, organik asitler, serbest yağ asitleri, serbest amino asitler, uçucu bileşenler ve duyusal nitelikleri üzerine etkileri incelenmiştir. Serbest yağ asitleri (SYA) ve uçucu bileşenler gaz kromatografisi-kütle spektrometresi (GK-KS); organik asitler ve serbest amino asitler (SAA) ise yüksek performanslı sıvı kromatografisi (YPSK) kullanılarak belirlenmiştir. Olgunlaşma süresi ve ambalaj materyalinin çoğu analiz parametresi üzerine etkisi önemli olmuştur. Toplam kuru madde, yağ, protein, tuz ve kül bidon tulum peynirine kıyasla deri tulum peynirinde daha yüksek tespit edilmiştir. Peynirlerde laktik asit başlıca organik asit olarak belirlenmiş olup; bidon tulum peynirine kıyasla deri tulum peynirinde daha hızlı yükselmiştir. Ambalaj materyali, peynirlerin toplam serbest yağ asitleri üzerine önemli bir etki yaratmamıştır. Ancak toplam serbest amino asit konsantrasyonları ise deri tulum peynirine kıyasla bidon tulum peynirinde daha yüksek belirlenmiştir. Valin, prolin, metiyonin, triptofan, lösin, fenilalanin, tirozin, glutamik asit ve lisin peynirlerde başlıca serbest amino asitler olarak belirlenmiş olup; toplam serbest amino asit konsantrasyonunun %78'ini oluşturmuşlardır. Uçucu bileşen kompozisyonu her iki tulum peynirinde de benzer olmakla birlikte; oranları arasında farklılıklar görülmüştür. Asit ve keton uçucu bileşenleri deri tulum peynirinde en fazla orandabelirlenen uçucu bileşenler olurken; bidon tulum peynirinde alkol ve ester uçucu bileşenleri en yüksek oranda belirlenmiştir. Peynirlerin duyusal nitelikleri üzerine ambalaj materyali ve olgunlaşma süresinin etkileri önemli olmuştur. Olgunlaşma sırasında genel kabul edilebilirlik yönünden bidon tulum peynirlerine kıyasla deri tulum peynirleri daha yüksek puan almıştır. Toplam esterler, etil asetat (P<0,05) ve 2-bütanon (P<0,05) genel kabul edilebilirlikle negatif korelasyon göstermiş olup; bu bileşenler bidon tulum peynirlerinde daha yüksek oranlarda belirlenmişlerdir.
