DEVELOPMENT OF DEEP FRYING EDIBLE VEGETABLE OILS

Abstract

ABSTRACTRefined soybean and rice‐bran oils have been selected as base oils for preparation of frying oils. Hexane and acetone fractionation of nontraditional tree seed oils (NTOs) such as sal, mango, mahua and palm fats was carried out at 5–20C. Chemical and chromatographic parameteres were used to fractionate each oil (NTOs) in order to obtain olein‐rich and stearin‐rich fractions. The stearin fraction obtained at 10 and 15C from hexane and acetone were identical and hence mixed together. The stearin fraction obtained from all the four NTOs were incorporated at 10% level with the conventionally refined (market sample) and physically refined (laboratory sample) soybean and rice‐bran oils in order to obtain frying oils. Heat stability parameters of the oils, namely free fatty acids (FFA%), peroxide value (PV), and iodine value (IV) were determined for base oils and frying oils after heating. Values for oil samples changed as follows: A (refined soybean oil and frying oils containing it) % FFA from 0.18 to 0.17–0.19, PV from 3.6 to 4.6–6.0 and IV from 125.3 to 109.2–115.8; B (refined rice‐bran oil and frying oils containing it) from 0.21 to 0.19–0.23 for % FFA, 4.0 to 4.6–6.7 for PV and 99.4 to 87.6–92.8 for IV; C (physical refined soybean oil and frying oils containing it) from 0.36 to 0.33–0.36 for % FFA, 5.7 to 7.4–11.2 for PV and 126.9 to 108.9–113.2 for IV; and D (physical refined rice bran oil and frying oils containing it) from 0.79 to 0.75–0.79 for % FFA, 7.1 to 8.2–11.3 for PV and 101.4 to 88.6–93.7 for IV, respectively. However, when base oils were heated as such, their deterioration was much faster. Fatty acid composition, determined by gas chromatography, also supported the results obtained by chemical means. These frying oils showed improved heat stability compared to their base oils.