Introduction: Nowadays, lack of time and busy work schedules have led to increase the demand for ready-to-eat foods. Furthermore, as cardiovascular diseases are on the rise in the world including our country, with nearly 40 percent of deaths being linked to these diseases, there is a growing demand for low-fat products. The main purpose of the deep frying process is to preserve the aroma and flavor of the ingredients in a crispy crust by immersing the food in hot oil. Frying at high temperatures affects the transfer of mass and heat, which causes some of the water to evaporate and be removed from the product, and the oil is moved into the product, replacing the extracted water. This study aims to use methods that reduce the absorption of oil in the fried product, which can reduce health concerns and increase consumer acceptance of the product.
Materials and methods: In this study, a day-old chicken breast fillets were used to prepare the samples. The weight of the samples was between 14.5 and 15 grams, with a diameter of 3.7. Coating solutions include aloe vera gel powder at three levels of 1.5, 3, and 4.5 % (w / v) and whey protein concentrate (WPC) at three levels of 2.5, 5 and 7.5 % (w / v), made with distilled water at 25C. Baguette bread was also used to make breadcrumbs. To coat the chicken breast fillet, the samples were immersed in the coating solution (control samples in distilled water) for 1 minute and then placed in breadcrumbs. After preparation, the samples were fried in an automatic fryer at a controllable temperature of 140 C for 6, 8, and 10 minutes, then the samples were cooled to room temperature for 10 minutes and tested for physicochemical properties. The tests included coating, weight loss, moisture content according to the standard AACC method, adsorption of oil by standard method AOAC, tissue measurement test based on the stiffness of the chicken tissue cutting (catching test), and color analysis of chicken samples using CIE Lab colorimetric system through the determination of color characteristics were performed.
Results & discussion: The results showed that the coated samples increased the absorption of the coating glaze due to the increasethe viscosity and thus the absorption of baking powder compared to the non-coated sample. The coating with hydrochloric materials based on barrier properties through strong hydrogen bonds between water molecules forms a gel layer with a high water holding capacity that prevents moisture from escaping. This subsequently reduces weight loss. Moreover, due to the inverse relationship between water and oil content, oil absorption was significantly decreased (p<0.01). Among the studied coatings, the highest moisture retention rate and the lowest oil absorption rate are related to the coated sample with 4.5% aloe vera and 7.5% WPC. As the concentration of aloe vera increased, the hardness of the samples decreased, which may depends on the effect of the meat protein to polysaccharide ratio. As the concentration of WPC increased, the stiffness of the samples increased, increasing the sulfhydryl groups, increasing the disulfide bonds in the meat's myofibrillar protein, and thus increasing the tissue stiffness. Increasing the frying time reduced the moisture and increased the oil absorption, weight loss, and stiffness of the samples. The coating reduces brightness due to the presence of various phenolic pigments, especially light- and heat-sensitive anthraquinones in aloe vera and lactose in WPC, and Maillard's reaction at high processing temperatures, resulting in increased browning index and darkening with increasing product color time. This is correlated with the Maillard reaction. Coating with aloe vera gel and WPC is effective in improving the physicochemical properties of fried chicken.