Canola oil, sunflower oil,

Canola oil is extracted from rapeseed and consumed all over the world due to its valuable ingredients [1]. It has a low amount of saturated and a substantial amount of monounsaturated fats with roughly 2:1 mono to polyunsaturated fatty acids [2]. In general, it contains 61% oleic acid which is classified as a monounsaturated omega-9 fatty acid, 11% α-linolenic acid and 21% linoleic acid which are omega-3 and omega-6 polyunsaturated fatty acids, and 7% saturated fatty acids [3,4]. Canola oil is second to olive oil in oleic acid content and intermediate among other vegetable oils in polyunsaturated fatty acid (PUFA). It contains high levels of PUFA compared to olive and palm oil but lower levels than corn, soybean, and sunflower oils [3]. In addition, it contains phytosterols, tocopherols, which are biologically active isomers of vitamin E [3,5], beta-carotenoids and chlorophylls [3]. Canola oil is extracted by slightly heating the crushed canola seeds dissolved in the hexane solvent or by cold press method [4]. Finally, it is refined using water precipitation and organic acid to remove gums and free fatty acids, filtering to remove color, and deodorizing using steam distillation [4]. Refining methods largely remove vitamin E, carotenoids and chlorophylls during bleaching [6] and deodorization processes [7].Refining process renders canola oil a hydrogenated mess of trans fatty acids and their consumption may lead to heart problems, blood platelet abnormalities, increased cancer risk and free radical damage [3].
Characterization of any edible oil is therefore very important because the problems related with its quality and adulteration [8,9] is very common across the world which is determined by its peroxide value, a most traditional and used parameter for measuring its deterioration [10,11]. Fluorescence spectroscopy, on the other hand, proved itself an on line, quick, non-invasive and reliable tool for the characterization of food
[12]. It has been used extensively as a fingerprint optical technique for the quality assurance of edible oils
In the present article, three types of canola oils have been spectroscopically investigated using fluorescence spectroscopy. It has been found that the commercially available canola oil brands do not contain vitamin E,
beta-carotene and chlorophylls, which should be naturally present. In addition, the effect of temperature on the cold pressed canola oil has been investigated to find a safe temperature range for cooking and frying of food.