Quality investigation of the most consumed refined seed oils after French fries’ domestic short-term deep-frying process

Abstract

Deep-frying is an attractive food preparation method and has been in use for centuries. It is a very popular culinary practice worldwide and can be used both industrially and domestically. Deep-fried food has a unique sensorial property, such as flavor, aroma, and texture. However, the chemical quality of the frying oil can be affected by the high temperatures normally used in deep-frying. Complex series of reactions that occur in vegetable oils during deep-frying (hydrolytic and oxidative rancidity processes) they are related to several mechanisms, such as reactive species, chemical composition of the lipid, environment, and process, influencing the speed and nature of the oxidative process. This paper aimed to analyze the quality of the vegetable oils most consumed by the population (refined soybean and sunflower oils) used in domestic short-term deep-frying process, using a domestic-grade electric fryer and a conventional method. French fries were used because they are a convenient product, highly consumed in industrialized countries. Domestic events of short-term deep-frying were carried out for three days, with one-week intervals. After each frying events, the refined oils were analyzed. Methodology consists in bromatological analyses of quality research applying analyzes of acidity and peroxide, in which the free acidity content, compounds formed by hydrolytic rancidity, and hydroperoxides content, the first compounds formed in the oil´s oxidative rancidification process, were analyzed. These parameters will be fundamental in oils oxidative evaluating during frying. According to the results, fresh vegetable oils samples remained within regulatory limits. However, after short-term deep-frying, free fatty acids and hydroperoxides content increased in both domestic short-term deep-frying using both vegetable oils, exception of sunflower oil after last day of frying. Additionally, there was no significant difference in the fatty acids value increase comparing with both domestic frying techniques. However, there was significant difference in hydroperoxide value comparing the oils between deep-frying techniques. However, in general even the oils have shown great thermal quality, bromatological analyses demonstrated that must be taken careful when reusing oils for short-term deep-frying. Seeing that the electric fryer is effective in oil quality compared preservation comparing with conventional method, probably due to temperature control and better sealing efficiency.