Yazar "Gueler, Zehra" seçeneğine göre listele

Listeleniyor 1 - 2 / 2
  • [ N/A ]
    Öğe
    Effects of breed and lactation period on some characteristics and free fatty acid composition of raw milk from Damascus goats and German fawn x Hair goat B1 crossbreds
    (Tubitak Scientific & Technological Research Council Turkey, 2007) Gueler, Zehra; Keskin, Mahmut; Masatcioglu, Tugrul; Gul, Sabri; Bicer, Osman
    The effects of breed and period of lactation on milk composition were investigated. For this purpose, 8 crossbred (3/4 German fawn 1/4 Hair goat) and 10 Damascus goats were kept under identical management conditions. Lactation period affected milk yield and milk composition in both goat breeds. Milk yield, lactation duration, and mean solid and fat values showed differences between the breeds. The mean values of total solid and fat of milk during lactation were 13.82 +/- 0.294% and 4.55 +/- 0.223% for the crossbreds, and 12.90 +/- 0.179% and 4.02 +/- 0.142% for Damascus goats, respectively. Although the percentages of short-chain free fatty acids (FFAs) (C-4 to C-8) in the milk of both breeds did not change during lactation, the other FFAs (C-10-C-18:3) significantly varied (P <= 0.05, P <= 0.01). The results showed that hexadecanoic (C-16), 9-octadecenoic (C-18:1), octadecanoic (C-18.), tetradecanoic (C-14)()), decanoic (C-10), and decanoic (C-12) FFAs were the most predominant FFAs in the milk of both breeds from March through September, but octadecanoic acid and tetradecanoic acid shifted during the last 2 months of lactation.
  • [ N/A ]
    Öğe
    Elution Conditions for Effective Separation on an Aged Sulfonated Polystyrene-Divinylbenzene (SPD) Column of Organic Acids from Meat
    (Springer, 2023) Dursun, Ahmet; Gueler, Zehra
    A modified elution condition for organic acids in meat chromatographed by aged sulfonated polystyrene-divinylbenzene (SPD) column was compared to common elution conditions in terms of efficiency, selectivity, resolution, peak shape, precision, and accuracy. The mobile phase concentration (mM), flow rate (mL/min), and column temperature (?) under common elution conditions (CECs) changed from 10 to 25, 0.6 to 0.2, and 60 to 40 in modified elution (MEC), respectively. A total of 15 peaks were detected in both elution conditions. Seven of them were confirmed with the available authentic organic acid standards including citric, pyruvic, succinic, lactic, acetic, propionic, and butyric acid. A good efficiency, selectivity, resolution, and peak shape were obtained for organic acids chromatographed on aged SPD column with MEC compared to CEC. The analyte was quantified using external standard technique. High response factor, expected correction factor, better calibration sensitivity and repeatability, and also accuracy for organic acids were observed under MEC. In particular, when peak broadening was observed in the aged SPD column, good chromatographic separation could be obtained with MEC in terms of resolution and peak shape was associated with better precision and recovery for organic acids in meat.