Effects of Oil Types on the Taste and Flavor Quality of Prepared Stir-fried Rice

Oil was one of the essential components in prepared stir-fried rice. In this study, the effects of oil types on the taste and sensory quality of prepared stir-fried rice were evaluated, considering moisture content, texture, color, and lipid oxidation parameters. In addition, the role of oil on the texture of prepared stir-fried rice was further explored according to moisture distribution and starch crystal structure. Results showed that the inward and outward migration of moisture during the cooking and stir-frying processes was restricted by oil, and the proportion of bound water in stir-fried rice was reduced while the proportion of free water was increased. The relative crystallinity and short-range order of starch in stir-fried rice was increased with the addition of oil, and formation of V-type starch-lipid complexes in the stir-fried rice starch was promoted. The hardness and adhesion of stir-fried rice was significantly decreased (P<0.05) while the springiness was increased with oil. Notably, the stir-fried rice obtained the greatest hardness value (7.62 N) and springiness (0.92) with the lard, and presented the highest relative crystallinity of starch. The surface morphology of stir-fried rice was improved with less surface cracks after cooking and stir-frying with all the oil samples. Moreover, the volatilization of aroma compounds was more pronounced in the prepared stir-fried rice with soybean oil, high oleic sunflower oil (Jinli), and palm oil (low melting point, Tianyijia). It was indicated by the peroxide, acid, and carbonyl value results of cooked and stir-fried rice that oil oxidation occurred mainly during stir-frying, with the lowest peroxide value observed in stir-fried rice prepared with palm oil (high melting point, Tianyijia). Correlation analysis revealed that the peroxide value and carbonyl value of oil were positively correlated with oil oxidation in stir-fried rice (P<0.05), while the acid value of oil was positively correlated with the adhesiveness of prepared stir-fried rice. This study provides a theoretical basis and practical guidance for the quality enhancement of prepared stir-fried rice.