Dados do Trabalho

Título

EFFECT OF THE FRYING PROCESS ON THE DYNAMIC INTERFACIAL TENSION OF COMMERCIAL OILS

Introdução

Interfacial tension is a fundamental property for evaluating vegetable oils, with important impacts on their production, application and digestion. For example, during frying, the direct transfer of heat from the hot oil to the cold food affects the oil-food interface, influencing the quality of the product. In view of this, the aim of this study was to evaluate the dynamic interfacial tension of three vegetable oils subjected to real frying experiments.

Material e Métodos

Commercial canola, sunflower and soybean oils were used to fry potatoes (ratio 0.2g/cm3) for 5 min at 180 °C. Measurements at the oil/water interface, before and after frying, were conducted on a drop profile analysis tensiometer PAT-1 (Sinterface, Berlin). The time scale of approximately 1 to 20s after droplet formation is considered suitable for measurements related to frying processes (immersion and start of boiling on the food surface). Therefore, data relating to the 20s time was selected for statistical analysis.

Resultados e Discussão

The results showed a decrease in interfacial tension as the interfacial film aged, both in the fresh oils and those subjected to the frying process, indicating the presence of surfactants. The interfacial tension (mN/m) for canola, sunflower and soybean oils was, respectively, 28.28±0.91, 41.67±0.27 and 23.43±0.26 before frying, and 18.73±0.27, 23.22±0.37 and 21.09±0.25 after frying.

Conclusão

The significant decrease (p<0.05) in the interfacial tension of the oils after frying was probably caused by the increase in surfactant substances from hydrolysis, peroxidation, degradation and polymerization reactions in the oils. The interfacial tension values varied significantly between the different oils analyzed, reflecting their chemical composition and extraction conditions. The higher interfacial tension of sunflower oil suggests greater resistance to thermal degradation and lower oil absorption in fried foods, resulting in higher nutritional and sensory quality. In short, the evaluation of dynamic interfacial tension is suitable for estimating and controlling the quality of oils in the face of processing conditions.