EFFECT OF SOME NATURAL HERBS INCORPORATION IN SUNFLOWER OILS ON ITS RESISTANCE AT FRYING TEMPERATURES

Abstract

Sunflower oil is an excellent source of essential fatty acids necessary for human body. Extending the frying life of oil is of commercial and economic importance. Therefore, improving the thermal stability of cooking oils could provide considerable savings to the food processors. The present work aims at evaluating thermal resistance of sunflower oil after the incorporation of three species of natural herbs, from Salvia genus and Allium ursinum, used in food as condiments or under other forms. By this treatment, we seek to preserve almost unchanged the oil quality during thermal treatment, by increasing the level of antioxidants from oil. For this study, four different frying temperatures i.e. 110, 150, 180 and 200ºC were applied for 30 minutes to sunflower oil before and after the addition of plants. At 110 ºC we have also made a kinetic study on samples stability in time. Official AOAC methods were used to determine free fatty acids content (FFA) and peroxide value (PV) of all samples during heating. The quality parameters of sunflower seed oil were improved by treatment with either Salvia officinalis., Salvia sclarea or Allium ursinum (wild garlic). Salvia and wild garlic exhibited a comparable high ability in reducing peroxide value (PV), probably due to their high content of polyphenols and flavonoids. In conclusion, the incorporation of Salvia and wild garlic into sunflower oil helped improve its thermal resistance and stability, which sustains their use in order to extend frying life of oils during food processing.