Stabilisation of frying oils with natural antioxidative components

Deep-fat frying is a complex, thermal chemical process that produces fried foods with desirable colour, appearance, flavour, and texture. Normally, le ss stable liquid oils are hydrogenated to enhance their oxidative stability for deep-fat frying purposes. However, considerable amounts of trans and p ositional isomer fatty acids are formed during hydrogenation, which are nut ritionally undesirable. The stability of frying oils is sometimes increased by careful blending of polyunsaturated oils with more saturated oils. The natural way of improving oxidative and flavour stability of frying oils and fats is by adding natural antioxidative components and precursors present in the plant kingdom, such as 'virgin' olive oil, sesame seed oil (SSO) and rice bran oil (RBO). A variety of natural antioxidative components, presen t in these oils, comprise tocopherols and tocotrienols, special sterols e.g . Delta5-avenasterol and sterol esters, squalene sesamolin, sesamol, sesami nol and related compounds, polyphenols, etc. Various antioxidative componen ts present in SSO and RBO are largely retained in Good-Fry(R) Constituents (GFC), manufactured according to European patent as well as USA and worldwi de patent applications pending (Silkeberg and Kochhar, 2000). Generally, palm olein, palm oil, partly hydrogenated rapeseed oil/soybean o il and/or their blends are mainly used by the frying industry for the produ ction of a variety of snack products and pre-fried convenience foods. Sever al new frying oils with good oxidative stability, which do not require hydr ogenation, are now commercially available on the European market, for examp le high-oleic sunflower seed oil stabilised with GFC. The results showed th at the addition of 6% GFC to unhydrogenated rapeseed provided crisps, produ ced on industrial scale, with stability similar to those fried in palm olei n without GFC. Shelf life of crisps fried in soybean oil, iodine value 130, was substantially increased by addition of 5% GFC. The Good-Fry(R) Constit uents can also be added, with advantages of flavour stability of fried snac ks, to oils such as palm oil or palm olein at lower levels of 2%. It is for ecasted, to meet an ever-growing consumer demand of 'healthier' snack produ cts, the usage of natural antioxidative components in stabilising frying oi ls rich in monounsaturated fatty acids (MUFAs) will grow tremendously.