The effect of roasting process on tiger nut oil properties and enhancing the oxidative stability of sunflower oil by blending with it

Many efforts are made to develop new resources of edible oils, specially non-traditional oils, due to the lack of recent resources. Tiger nut is a popular Egyptian snack with high non-traditional oil content. The present investigation aimed to study the effect of roasting process on the TNO properties and study the effect of adding roasted tiger nut oil (RTNO) to sunflower oil (SFO) in order to enhance SFO stability. Proximate analysis, fatty acid composition, total phenolic content (TPC), carotenoids content, antioxidant capacity and oxidative stability of roasted and unroasted TNO were measured. 10, 20, and 30 % of RTNO were added to SFO and thechange of fatty acid composition and oxidative stability were studied. The oil blends were heated for four weeks in the oven at 60 degrees C and the lipid oxidation of the oil samples were studied using FTIR spectrophotometer. Fatty acid profile of TNO showed high amount of oleic acid about 70%, followed by palmitic acid (13.05%), linoleic acid (9.23%) and stearic acid (5.77%). The results showed a decrease in the moisture content, free fatty acid % and iodine value. Peroxide value was increased by heating in roasting process while fatty acid composition almost didn't change by roasting. TPC, antioxidant activity and oxidative stability were also increased by roasting process. Also, the addition of RTNO to SFO increased the mono-unsaturated fatty acids and decreased the poly-unsaturated fatty acid by increasing the concentration of RTNO which make it more nutritionally valuable. Moreover, the addition of RTNO to SFO increased its oxidative stability. The results showed that tiger nut tubers are promising source for non-traditional edible oil with high stability, shelf life and nutritional value.