Evaluation of the quality of sunflower oil subjected to frying processes under controlled conditions

Abstract

The food frying process causes physicochemical modifications in the oils, affecting their sensorial characteristics and eventually producing toxic effects. The objective of this work was to study the degradation of sunflower oil used in potato immersion frying, considering the free fatty acid content, peroxide index and refractive index, high­lighting the critical and optimal points of the process. Experimental planning and response surfaces were used, considering the variables temperature, total process time and potato:oil ratio. The three variables showed a sig­nificant linear effect on the percentage of free fatty acids (R² = 98.3%). The value of the peroxide index was strongly influenced by temperature and, to a lesser extent, by other variables (R² = 98%). The refractive index was influenced linearly and quadratically by time and temperature and only linearly by the potato:oil ratio (R² = 97.2%). These results indicate that frying processes conducted at warmer temperatures may increase the useful life of the oil, whose characteristics directly influence the quality of the final product.