This study aimed to investigate the oxidation profile of wheat germ oil extracted from raw germ during the stabilization with microwave (MW) treatment, and the kinetics of the oxidation parameters (free fatty acids (FFA), peroxide value (PV), thiobarbituric acid (TBA), α-tocopherol, lipase (LA) and lipoxygenase (LOX) enzymes activities) under different storage conditions. For stabilizing raw germ, the MW was treated at 700 W for three minutes. The oxidation parameters for the kinetic modeling were analyzed at different storage times (0, 15, 30, 45, 60,75, 90, and 105. days) and storage temperatures (-18, 0, 4, and 25 °C). The parameters were mathematically modelled and the PV and LA fitted well to the zero-order kinetic model, while FFA with α-tocopherol and TBA followed the first and second-order kinetics, respectively. The kinetic constant (k) was described by an Arrhenius equation and the activation energy ranged from 5.72 to 18.5 kJ/mol for the stabilized germ.

Van yöresi başta olmak üzere, Doğu Anadolu Bölgesinde sık tüketilen geleneksel kahvaltılık çeşitlerinden biri de kavuttur. Kavut; kavut unu olarak isimlendirilen ve buğdayın öğütülüp, kavrulmasıyla elde edilen tam buğday ununun, şeker, süt ve yağ ile pişirildikten sonra, isteğe göre bal veya reçelle tatlandırılan lezzetli ve besleyici bir gıdadır. Bu çalışmada; Van yöresindeki farklı üreticilerden 20 adet kavut unu temin edilerek, fizikokimyasal ve enzimatik değişimleri incelenmiş, toplam fenolik madde ve antioksidan aktiviteleri araştırılmıştır. Karbonhidrat içeriği oldukça yüksek bulunan kavut unlarında en yüksek değer %75.49 olarak bulunmuştur. Lipaz enzim aktivitesi ortalama 2.12 U g-1 olarak hesaplanan çalışmada, enzim aktivitesinin kavurma prosesiyle birlikte tamamen inaktif hale gelemediği ancak büyük oranda kısıtlandığı kanısına varılmıştır. Metanol çözücüsü kullanılarak elde edilen kavut unu ekstraktlarının antioksidan aktiviteleri DPPH ve TEAK yöntemleri kullanılarak belirlenmiştir. Kavut unlarının toplam fenolik madde miktarı 2404.167-2716.667 mgGAE kg-1 arasında değişmekte olup, antioksidan aktivite değerleri sırasıyla ortalama %42.642 ve 12.972 mmol troloks g-1 olarak belirlenmiştir.

The effect of deep fat frying temperatures, ranging from 160 to 190 oC, on frying parameters including the heat transfer coefficient (he), mass transfer coefficient (ke) and effective moisture diffusivity (De) were investigated during deep fat frying of churro that is fried dough pastry. Therefore experimental studies were conducted for both heat and mass transfer phenomena and mathematical model was developed for simultaneous transfer by using Newman technique for churro actual geometry (3-D cylindrical shape). Fourier’s and Fick’s laws were applied for computation of coefficients of heat and mass transfer. The he coefficients were 437.360-93.535 W/m2K in the temperatures range of 160 to 190 oC. However, the value of ke and De increased by an increase in oil temperature during frying. The maximum values were determined as 17.36 x10-5 m/s and 2.48 x10-5 m2/s at 190 oC for ke and De, respectively. Model and experimental data had good agreement and the transfer coefficients followed the first order kinetic model with high R2 and low RMSE values. There was found an Arrhenius equation between the effective moisture diffusivity and deep fat frying temperature, so the value of activation energy was calculated as 63.546 kj/mol.