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Öğe Changes in Olive and Olive Oil Characteristics During Maturation(SPRINGER, 2013) Yorulmaz, Asli; Erinc, Hakan; Tekin, AzizChanges in olive properties and oil quality, oxidative stability, phenolic and chemical composition of two common Turkish varieties (Memecik and Edremit) during maturation were investigated. Olive samples were collected in their own growing region for five different harvest dates and processed to oil with a laboratory scale mill. Metabolic behaviors of these two varieties along with the maturation were different in terms of some compositional parameters. Oleic acid, triolein, b-sitosterol, oleuropein, hydroxytyrosol, and tyrosol contents of olive or olive oils fluctuated with maturation. However, changes in average weight, flesh/pit ratio, water and oil contents of the olives were observed. Phenolics such as trans cinnamic acid contents of both olive fruits decreased whereas cyanidin 3-O-glucoside and cyanidin 3-O-rutinoside anthocyanins increased. Free fatty acids of virgin olive oils were found independent of maturity although some slight changes were determined in peroxide value, dien and trien conjugations. Some compositional parameters such as pigment concentration, tocopherols, stearic acid, linolenic acid, palmitodiolein and monounsaturated/polyunsaturated fatty acid ratio decreased while linoleic acid, dioleolinolein, palmitooleolinolein and Delta-5-avenasterol percentages increased with the maturation. A clear discrimination was observed with principal component analysis. The data obtained can also be considered useful for providing information to determine the ideal maturity stage.Öğe MALAKSİYON SICAKLIK VE SÜRESİNİN ZEYTİNYAĞININ BAZI ÖZELLİKLERİ ÜZERİNE ETKİSİ(2018) Erinç, Hakan; Yorulmaz, Aslı; Tekin, AzizÇalışmanın amacı farklı malaksiyon süre (30, 60 ve 90 dk) ve sıcaklıklarının (30, 45 ve 60°C) Edremit yağlıkve Memecik zeytinyağlarının kalite kriterleri ile oksidatif stabiliteleri üzerine etkilerinin belirlenmesidir. Buamaçla Edremit yağlık ve Memecik çeşitlerine ait zeytinler laboratuvar koşullarında kırma, malaksiyon,presleme ve santrifüjleme işlemlerine tabi tutularak natürel sızma zeytinyağları elde edilmiştir. Çalışmada,Memecik zeytinyağının serbest yağ asitliği, peroksit değeri ve toplam fenol miktarının Edremit yağlıkzeytinyağından daha yüksek olduğu, bununla birlikte K232 veK270 ile indüksiyon periyodunun Edremit yağlıkzeytinyağında daha yüksek olduğu tespit edilmiştir. Malaksiyon süresi ve sıcaklığının zeytinyağlarının serbestyağ asitlikleri, K232 ve K270 değerleri ve toplam fenol miktarları üzerine etkisi olmadığı belirlenmiştir. Bununlabirlikte malaksiyon süresinin artmasıyla birlikte peroksit değerlerinde hafif bir artış olduğu gözlenmiştir.Malaksiyon sıcaklığının artması ile indüksiyon periyodunun arttığı saptanmıştır. Diğer taraftan, zeytinyağlarınyağ asidi kompozisyonları üzerine malaksiyon şartlarının önemli bir etkisi olmamıştır.Öğe Oxidative changes in hazelnut, olive, soybean, and sunflower oils during microwave heating(Taylor & Francis Inc, 2017) Javidipour, Issa; Erinc, Hakan; Basturk, Ayhan; Tekin, AzizThe effects of microwave heating for 3, 6, and 9 min at a frequency of 2450 MHz on fatty acid composition, tocopherols, iodine value, free fatty acids (%), peroxide value, conjugated dienes and trienes, and hexanal contents of refined hazelnut, soybean, sunflower, and virgin olive oils were investigated. A significant (p < 0.05) decrease was observed in linoleic and linolenic acids contents of soybean oil during exposure to microwave heating. Tocopherol contents of oil samples significantly decreased (p < 0.05) during microwave heating. Free fatty acids of the samples slightly increased and iodine value showed reduction throughout the process. Conjugated dienes contents of samples showed an increasing trend up to the 6 min, followed by a reduction at 9 min. Conjugated triene fatty acids of all the samples significantly increased (p < 0.05) throughout the application. While peroxide value showed increasing trend up to the 3 min and sharply decreased at 9 min, hexanal contents of refined hazelnut, virgin olive, soybean, and sunflower oils increased 63, 28, 55, and 389 fold, respectively, after 9 min exposure to microwave heating. Kinetic analysis of data showed that the reaction orders for peroxide and hexanal formation were zero and first order, respectively, and in the tested oils the reaction rate followed the order: soybean oil ? sunflower oil ? hazelnut oil ? virgin olive oil for peroxide, and sunflower oil ? soybean oil ? hazelnut oil ? virgin olive oil for hexanal formation. It was concluded that hexanal could be considered as a parameter for evaluation of the quality of oils exposed to microwave heating.Öğe THE EFFECT OF IRRIGATION ON OLIVE AND OLIVE OIL CHARACTERISTICS(2019) Yorulmaz, Aslı; Erinç, Hakan; Tatlı, Abidin; Tekin, AzizThe aim of the study was to identify the changes in olive and corresponding olive oil characteristics in responseto irrigation. Five olive cultivars (Halhalı, Sarı ulak, Nizip Yağlık, Kilis Yağlık and Karamani) from Turkish originwere harvested from their own traditional growing region (Mardin, Mersin, Gaziantep, Kilis and Hatayrespectively) from both irrigated and non-irrigated trees (rain-fed) for two consecutive crop years. Olives wereprocessed to oil with a laboratory scale system. Olive fruits were analyzed for their physico-chemical propertiesand phenolic composition and olive oils were analysed for fatty acid, triacylglycerol and sterol composition.Results have shown that average weight, flesh/pit ratio of olives were lower and dry matter and oil content werehigher in rain-fed trees than irrigated ones. Phenolic content and composition of fruits were cultivar dependentand responded differently to water supplement. Fatty acid composition of olive oils mainly remained unchanged,however the concentration of individual triacylglycerols behaved in distinct ways. Total sterol and ?-sitosterolcontents increased and decreased for various cultivars whereas ?-5-avenasterol increased in all cases. Sarı ulakvariety was well separated from other varieties by principal component and hierarchical cluster analysis both inrain-fed and irrigated treatments.
