Efficacy of phenolic compounds from bay leaf (Laurus nobilis) as natural antioxidants in the enhancement of edible oil thermo-resistance

Edible oils are lipids rich in polyunsaturated fatty acids, mak-ing them susceptible to oxidation and requiring supplementation with synthetic or, more interestingly, natural antioxidants. The present inves-tigation aimed to evaluate the use of phenolic compounds extracted from bay leaves for enhancing the thermo-stability of soybean oil. Soybean oils prepared with different concentrations of a phenolic extract (20, 40 and 60 mg/l) and the control oil were evaluated during heat treatment (170 degrees C, every 24 h for 3 days) by monitoring UV absorption coef-ficients, acidity, peroxide value, iodine value as well as total phenolic content and antioxidant activity. The results showed that the phenolic compounds of bay leaf reduced the incidence of thermo-oxidation of soybean oil, as manifested by lower UV absorption coefficients, acidity, and peroxide value, and protected the double bonds better. This protec-tion was more efficient when the phenolic concentration increased, and this was related to their antioxidant activity. The phenolic compounds of bay leaves, especially at 60 mg/l, demonstrated the best efficiency in enhancing the protection against thermo-oxidation of soybean oil during heat treatment, which opens some perspectives for their use in the oil industry.