Yazar "Durmaz, Goekhan" seçeneğine göre listele

Listeleniyor 1 - 5 / 5
  • Küçük Resim Yok
    Öğe
    Classification of eight pomegranate juices based on antioxidant capacity measured by four methods
    (Elsevier Sci Ltd, 2009) Cam, Mustafa; Hisil, Yasar; Durmaz, Goekhan
    The antioxidant capacity of pomegranate juices (PJs) obtained from eight cultivars were determined by the scavenging activity against 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2'-azino-bis(3 -ethyl-benzothiaz-oline-6-suffonic acid) (ABTS) and P-carotene-linoleate model system. Total phenolic content (TPC) and total anthocyanin content (TAC) were also determined and found to vary between the range of 208.3343.6 mg catechin equivalents and 8.1-36.9 mg cyanidine-3-glucoside equivalents per 100 ml of PJ, respectively. Cultivar Izmir 8 showed the highest scores for trolox equivalent antioxidant capacity (TEAC) as 418.3 +/- 5.2 mg/100 ml of PJ, anti-lipid peroxidative activity (ALPA) as 93.5 +/- 1.8% and efficient concentration (EC50) as 29.8 +/- 2.9 ml of PJ/g of DPPH. The hierarchy of PJs for antioxidant capacity with respect to their TEAC and ALPA values was 18 > 11499 > 110 > 11264 > 11479 > 126 > 123 > Zivzik. Interrelationships among the analyzed parameters and PJs obtained from eight cultivars were investigated by principal component analysis (PCA). Dimension of data set was reduced to two components by PCA accounting for the 93% of the total variance. Eight PJs were classified into three groups by cluster analysis (CA). (C) 2008 Elsevier Ltd. All rights reserved.
  • Küçük Resim Yok
    Öğe
    Determination of 5-hydroxymethyl-2-furfural and 2-furfural in oils as indicators of heat pre-treatment
    (Elsevier Sci Ltd, 2010) Durmaz, Goekhan; Goekmen, Vural
    This study describes a method for the determination of 5-hydroxymethyl-2-furfural (HMF) and 2-furfural (F) in oils. The method entails liquid-liquid extraction and reversed-phase liquid chromatography. Spiked hazelnut oil was used to test the accuracy and reliability of the method. Furan compounds were extracted from oil using 70% methanol. Mean recoveries were 97 +/- 2% and 99 +/- 1% for HMF and F, respectively. To investigate the presence of HMF and F in oils, seven oily nuts and seeds were roasted at 180 degrees C for 30 min. Different oils were found to contain HMF and F ranging from 0.8 to 13.8 and 1.4 to 8.7 mg/kg, respectively. Increasing solvent polarity also increased the rate of HMF transferred to the oil. Spectral analyses of the 70% methanol extracts indicated that absorbance at 285 nm may be used to monitor the accumulation of furan compounds in oil phase during the roasting process of nuts. (C) 2010 Elsevier Ltd. All rights reserved.
  • Küçük Resim Yok
    Öğe
    Protective effect of dietary apricot kernel oil supplementation on cholesterol levels and antioxidant status of liver in hypercholesteremic rats
    (Wfl Publ, 2009) Kutlu, Tuerkan; Durmaz, Goekhan; Ates, Burhan; Erdogan, Ali
    Apricot kernel oil is a rich source of MUFA and PUFA, including mainly oleic (about 70%) and linoleic acids, respectively. In addition, apricot kernel oil could be considered as a good source of bioactive compounds such as tocopherols and phytosterols consisting mainly of they gamma-isomer and beta-sitosterol, respectively. Given to its high content of oleic acid, apricot kernel oil is considered as a healthy supplement in diet. In the present study, we investigated the effects of apricot kernel oil supplementation on cholesterol and malondialdehyde (MDA) levels and glutathione peroxidase (GPx) and catalase (CAT) activity in hypercholesteremic rats. Hypercholesteremia was produced by feeding rats with a semisynthetic diet that contained high cholesterol and cholic acid. A high cholesterol diet caused a decrease in CAT and GPx activity, while apricot kernel oil caused a significant activity increase of these enzymes (P < 0.05). The group fed with apricot kernel oil supplementation showed higher enzyme activities than sunflower oil groups irrespective of cholesterol (P < 0.05). Results of the present study indicate that apricot kernel oil causes improvement in liver antioxidant status of rats in comparison to sunflower oil which is a commonly consumed vegetable oil.
  • Küçük Resim Yok
    Öğe
    Roasting-Related Changes in Oxidative Stability and Antioxidant Capacity of Apricot Kernel Oil
    (Wiley, 2010) Durmaz, Goekhan; Karabulut, Ihsan; Topcu, Ali; Asilturk, Meltem; Kutlu, Tuerkan
    Apricot kernels were roasted for various lengths of time (0-30 min) at 180 A degrees C and changes in the oxidative stability, antioxidant capacity, color, as well as the level of tocopherols and fatty acids of the apricot kernel oil (AKO) were monitored. While the level of tocopherols decreased, the oxidative stability and antioxidant capacity of AKO increased with roasting, probably due to the formation of antioxidative Maillard reaction products (MRPs) during the roasting. Medium roasted samples (15-20 min) were found to be more resistant to oxidative deterioration. The oil from the 30-min roasted sample was more susceptible to oxidation compared to the oil from the 20-min roasted sample in most of the stability tests. Relatively shorter roasting periods (5-10 min) also led to a decrease in oxidative stability in comparison to the unroasted sample. Brownish color and antiradical activity increased with roasting and the highest values were measured in the 30 min roasted sample.
  • Küçük Resim Yok
    Öğe
    Some Physical and Chemical Changes during Fruit Development of Five Common Apricot (Prunus armeniaca L.) Cultivars
    (Japanese Soc Food Sci & Technology, 2010) Durmaz, Goekhan; Cam, Mustafa; Kutlu, Tuerkan; Hisil, Yasar
    Five apricot (Prunus armeniaca L.) cultivars were examined throughout fruit development period to monitor the changes in quality characteristics including hardness, Brix, color, titratable acidity and pH. Changes in the amount of sugars (fructose, glucose and sucrose) and organic acids (citric, malic and quinic) were also determined by HPLC. The predominant sugar of cultivars found to be glucose at the initial ripening stages; however, sucrose or glucose became predominant at the end of fruit maturation. Sugar/acid rate was found to be the highest in Hasanbey (HB) cultivar during unripe period, while Kabaasi (KA) showed the highest value at full ripeness. Low soluble solid containig varieties of Zerdali (ZD) and HB reached fruit maturity earlier than the other cultivars. Soganci (SO) measured as the hardest fruit at maturity while ZD was the softest cultivar. Chroma as a measure of color, was found to be well corelated with maturity level rather than L value. In the course of ripening, total acid content decreased along with the increasing amount of total sugar for all cultivars.