تقويت كرايوژل ژلاتين با استفاده از خاك رس و سيتريك اسيد و كاربرد آن به عنوان جاذب در افزايش كيفيت روغن سرخ كردني مصرف شده

Deep-frying is a popular an‎d convenient method for food preparation. In this process, oil is exposed to high temperatures for extended periods, leading to the formation of harmful compounds such as peroxides, free fatty acids, aldehydes, an‎d polar compounds through physical an‎d chemical reactions, which deteriorate the oil. Therefore, regular replacement of the oil during the frying process is crucial, as prolonged an‎d continuous use of oil at high temperatures results in the accumulation of thermally degraded compounds, significantly affecting both the sensory quality an‎d safety of fried foods. In recent years, efforts have been made to extend the useful life of frying oils through various approaches to make the process economically viable for producers. Active filtration is one of the most common methods, which relies on the use of an adsorbent in used oils to selec‎tively remove harmful compounds. After adsorption, the adsorbent along with the impurities is removed through filtration, thereby recovering the oil an‎d enhancing its shelf life. Although synthetic adsorbents have demonstrated effective performance in industrial refining processes, there has been an increasing deman‎d for alternative solutions that are sustainable an‎d cost-effective. Consequently, researchers have turned to the use of natural an‎d environmentally friendly adsorbents, such as cryogels based on polysaccharides an‎d proteins, to optimize the oil refining process. The objective of this study was to produce a gelatin-based cryogel as the primary material an‎d to incorporate clay an‎d citric acid for reinforcement, serving as a natural, inexpensive, an‎d eco-friendly adsorbent for removing harmful compounds from used frying oils an‎d extending their shelf life. This study was conducted in four sections. In the first section, cryogels with a fixed gelatin concentration (5%) an‎d varying concentrations of citric acid (1.67% an‎d 2.5%) an‎d clay (1.25% an‎d 1.67%) were prepared by freeze-drying, an‎d their properties were eva‎luated. The cryogel containing 5% gelatin, 1.67% citric acid, an‎d 1.67% clay (GA1C2) was selec‎ted as the optimal cryogel. In the second section, the selec‎ted cryogel was added to oil at concentrations of 1–3% with contact times ranging from 10 to 50 minutes. Oil quality indices were eva‎luated, an‎d response surface methodology identified the optimal conditions as 1% cryogel concentration an‎d 40 minutes of contact time. In the third section, for kinetic analysis, free fatty acid content, peroxide value, thiobarbituric acid value, an‎d color of the oil samples were measured at 0, 5, 10, 15, 20, 30, an‎d 40 minutes, an‎d the best kinetic model for each test was determined using MATLAB software. In the fourth section, the performance of the natural adsorbent (GA1C2 cryogel) was compared with a synthetic adsorbent (a mixture of silica gel an‎d magnesium silicate) at 1% concentration an‎d 40 minutes of contact time. The results indicated that the natural adsorbent significantly outperformed the synthetic adsorbent in reducing peroxide an‎d thiobarbituric acid values an‎d improving the oil color.

اميرحسين گلي

علي فروهر

هاجر شكرچي زاده , مهرنوش جعفري