Influence of Industrial Processing on Physicochemical Properties and Composition of Vegetable Oils

Abstract

Vegetable oils are a choice of food as daily diet in many countries for several years. During industrial processing crude vegetable oils converted into high quality oil products that are fit for human consumption and meet market requirements at minimal cost. However, without refining crude oils are unsuitable for use in most food applications due to the presence of some unwanted components. Refining is the key factor in edible oil production aimed to remove free fatty acids, odiferous, dark color and pigmented materials of crude oil by neutralization, bleaching and deodorization steps to obtain odourless, bland and oxidatively stable oils, which are acceptable to consumers. Therefore, in the first part of study research work was carried out to determine physiochemical properties of cottonseed varieties (RH-112, Lankart-57, K-25, F20 and D-9) and their extracted oil. Among the physicochemical parameters of cottonseed, significant variation was detected in the average weight of seeds (59.5 mg-77.3 mg per single seed), moisture (6.2-8.5%) and oil content (12.01 to 14.55%). While chemical properties such iodine value, saponification value (SV), peroxide value (PV), and free fatty acids (FFA) were ranged between 93.90-105.76gI2/100g, 181.83-190.55mgKOH/g, 1.0-6.0mEq/Kg and 17.30- 38.80%, respectively. In the second part, research study was carried out for the rapid determination of FFA in cottonseed oil varieties by FTIR spectroscopy. Results indicated that FTIR method in combination with PLS/PCR could be used as a greener alternative to standard titration method. In the third part of study, research work was carried out on the influence of industrial refining steps (crude, neutralized, bleached and deodorized) on the physicochemical properties including fatty acid composition (FAC) of cottonseed, sunflower, canola and soybean oil was also checked. The results indicated that industrial processing has greater impacts on some physicochemical properties of cottonseed, sunflower, canola and soybean refined oils. The major impact among physical parameters from crude to deodorize was observed in the reduction of color and smoke point from 87-60% and 4.5-3.0%, VI respectively. Among chemical parameters major variations during refining from crude to deodorized was observed in FFA 1.70-0.15%, 0.56 to 0.06%, 1.16 to 0.08% and 1.26 to 0.05%, SV 175 to 173, 178.5 to 177.2, 173.6-173.2 and 177.0 to 176.1mgKOH/g oil, PV 3.4-1.2, 3.2 to 0.9, 2.9 to 1.3 and 3.5 to 1.8 mEqO2/Kg oil for cottonseed, sunflower, canola and soybean oil, respectively. Whereas, reduction of soap content in neutralization to deodorization steps was observed in the range of 61.0 to 15.5, 121.0 to 30.4, 60.8 to 15.1 and 61.0 to 15.2 ppm for cottonseed, sunflower, canola and soybean oil, respectively. The impact of refining processes on the FAC was observed less than 1% for cottonseed, sunflower, canola and soybean oil. Results suggested that overall deodorization process has greater impact on physicochemical properties to improve the quality and stability of cottonseed, sunflower, canola and soybean oil.