A new generation of frying oils

Traditional edible oils have high polyenoic acid contents, mainly linoleic acid, sometimes with a smaller amount of linolenic acid. Consequently, they are unstable against oxidation, especially under deep frying conditions. Novel high-oleic vegetable oils have been developed which contain low amounts of polyenoic fatty acids. Their relative resistance against oxidation is lower at deep frying temperatures in comparison with storage conditions, however, high-oleic oils were found advantageous for deep frying. High-oleic oils are more stable than low-linolenic oils. High-oleic sunflower, safflower or peanut oils have the best prospects for large-scale applications. The stability can be improved by the addition of antioxidants such as tocopherols.  

Oxidative changes of vegetable oils during microwave heating

The oxidative stabilities of pork lard, sunflower, zero-erucic rapeseed, peanut and high-oleic peanut oils were tested under microwave heating conditions. Vegetable oils and lard were heated in a microwave oven for up to 40 min between 25°C and 200°C. The peroxide value, the contents of conjugated dienoic and trienoic acids, and polymers were used as markers of lipid degradation. Sunflower oil was found the least stable oil because of a high polyenoic acid content and a low content of γ-tocopherol. Rapeseed oil was more stable because of a lower polyenoic acid content and a high γ-tocopherol level. Conventional peanut oil was relatively stable, but substantially less stable than high-oleic peanut oil. Pork lard and high-oleic peanut oil formed only low levels of polymers due to a low polyenoic acid content.