Thermal stability of some flavonoids and phenolic acids in sheep tallow olein

Abstract

AbstractIn this study, the thermal stability of some phenolic antioxidants including flavonoids (quercetin and catechin) and phenolic acids (gallic acid, tannic acid, ellagic acid and caffeic acid) in tallow olein was investigated. Tallow olein fractionated from sheep tallow fat was used as a medium to study the antioxidant activity at 120, 140, 160 and 180°C. In order to extract tallow olein, a three‐stage fractionation method was performed on sheep tallow fat at the constant temperatures of 25, 15 and 5°C using acetone as a solvent. The results suggested that quercetin and ellagic acid had the highest thermal stability amongst others, while gallic acid and caffeic acid exhibited the least thermal stability.Practical applications: The sheep tallow fat has been primarily used in soap manufacturing and its application as an edible fat has been limited due to its high content of saturated fatty acids. Extraction of the liquid phase of tallow fat (tallow olein) by fractionation reduces its long‐chain saturated fatty acid content to an acceptable level for edible consumption. The fractionation process, as negatively affects the stability to autoxidation, should be followed by stabilisation with antioxidants. The recent interest in natural antioxidants encouraged the authors to investigate the thermal stability of phenolic antioxidants in tallow olein. It is necessary to determine the thermal stability of antioxidants to predict their appropriateness to be used in high‐temperature applications such as deep frying. Fractionation and stabilisation with appropriate antioxidants are the important steps to utilise tallow olein as an edible oil for different applications in salad formulations, cooking and frying.