Abstract
The aim of this work is to study the effects of drying conditions on the quality of extracted pricly pear seed oil, specifically alpha-tocopherol content. Drying experiments were carried on following a full 2(3) factorial design using a vertical drying tunnel. The temperature range was 45 to 70 degrees C, relative humidity range was 15 - 30% and air velocity was 1 and 2 m/s. The Midilli-Kucuk model was found with satisfaction describing the seed air drying curves with a correlation coefficient of 0.999 and a standard error of 0.01. For each drying condition, the extraction of fixed oil seeds was performed at cold using mechanical pressing method. The oil quality was evaluated on the basis of the alpha-tocopherol content. The alpha-tocopherol was identified and quantified by high-performance liquid chromatography (HPLC-UV). According to the experimental results, it was found that convective drying of thin layer of seeds at soft air conditions, drying temperature of 45 degrees C, relative humidity of 15% and air velocity of 1 m/s give the optimal quality of extracted oil in terms of alpha-tocopherol content.