Lime (Citrus aurantifolia) Peel Effect on Peroxide Value of Cooking Oil

Abstract

Cooking oil is a staple in everyday life. Economic has been the reason of the repeated use. The quality of cooking oil can be known from taste, colour, and aroma. In terms of aroma, rancidity is caused by the presence of peroxide. Peroxide is a sign of oil breakdown or damage due to oxidation, which causes a rancid odour. Lime peel is used as an antioxidant because it contains vitamin C, flavonoids, and carotenoids. Damage to cooking oil can't be prevented but can be lowered by giving antioxidants from lime peel. This study aims to determine the effect of lime peel extract on the peroxide number in cooking oil. Antioxidant content of lime peel was measured by spectrophotometric absorbance of vitamin C, flavonoid and carotene content. Peroxide value was asses by titration. Oil clarity was also measured by spectrophotometric to confirm peroxide value. The method used in this study was an experiment using a complete randomized design with two factorials. The first factor is the type of solvent (distilled water, ethanol, and chloroform). The second factor is the extract concentration (70, 80, and 90) μg / ml. Peroxide number measurement was analysed using ANOVA (p <0.05) and continued with the Duncan test. Antioxidant content showed that lime peel contains vitamin C, flavonoid and carotene with highest in vitamin C. Peroxide value measurement obtained that distilled water extract concentration of 90 μg / ml had the lowest peroxide number of 0.56 MEquiv O2 / Kg while the highest value was found in distilled water extract of 80 μg / ml concentration (0.96.56 Mequiv O2 / Kg). Clarity of the oil was found best at 90μg/ml concentration (0.38). It can be concluded that lime peel extract significantly gave effects on peroxide number of cooking oil. Both concentration and extract solvent determine the peroxide number.