Influence of Drying, Pressing, and Antioxidants on Yield and Oxidative Stability of Cold Pressed Oils

Abstract

Investigated were the influence of drying and pressing parameters of rapeseed, sunflower, and safflower seeds on oil yield, as well as antioxidant addition on the oxidative stability of cold pressed oils. The parameters of the oilseeds and cold pressed oils quality (moisture content, iodine value, saponification value, peroxide value, free fatty acids, and insoluble impurities content) were determined using standard methods. In terms of oxidative stability, rosemary, green tea, and pomegranate extracts were used as natural antioxidants, and propyl gallate was used as synthetic antioxidant. The results showed that the moisture content of the oilseeds, as well as nozzle size and electromotor frequency of the press had an effect on the yield of cold pressed oil. By reducing the nozzle size and electromotor frequency, the volume of produced cold pressed oil increased. Rosemary extract effectively increased the oxidative stability of sunflower and safflower oils, and green tea extract increased the stability of rapeseed oil. Greater stabilisation of the tested oils was achieved with the addition of 0.4 % of natural antioxidants compared to the addition of 0.2 %. The synthetic antioxidant, propyl gallate, failed to stabilise safflower oil, and unlike the natural antioxidants, it was less protective for rapeseed and sunflower oil.

The Antioxidant Effect of Burdock Extract on the Oxidative Stability of Lard and Goose Fat during Heat Treatment

“…Thiobarbituric acid-reactive substances and peroxide values were monitored during butter heating at 50 • C and at 110 • C. The results showed that butylated hydroxyanisole at 200 mg L −1 was equally efficient at suppressing butter oxidation at 50 • C as caffeic acid, gallic acid, and catechin at 80 mg L −1 . Furthermore, gallic acid was more efficient than butylated hydroxyanisole at inhibiting the oxidation of butter at 110 • C. Moslavac et al [37] studied the effect of natural antioxidants (sage extract, rosemary extract, olive pomace extract, α-tocopherol, mixture tocopherol) on the oxidative stability of pork fat using the sustainability test at 98 • C. The results showed that rosemary extract more effectively protected pork fat against oxidation compared to the other antioxidants we tested. It was reported that heating chicken fat at 70 • C and storing it for two and four days significantly increased the amount of lipid oxidation, as shown by TBARS.…”