Curry leaf (Murraya koeneigii) extract as a natural source of antioxidants for enhancing the oxidative and thermal stability of ghee
Mohammed Arshath, M. P. Rahila, M. P. Divya, J. L. Smitha, S. Athira and P. Sudheerbabu
Ghee is used for making various sweets and dishes in addition to its various culinary purposes. In the course of such preparations, ghee is subjected to different degrees of heat treatment which on combining with air can undergo considerable physico-chemical changes. The high temperature cooking process creates a series of complex chemical reactions in ghee which affects the sensory and the functional properties of foods as well as the ghee used. This leads to adverse health effects on consumers. One of the best ways to protect ghee from autooxidation and thermal oxidation is by the incorporation of antioxidants during their processing. Addition of synthetic antioxidants is restricted in several countries. Scientific investigations have also found that the use of synthetic antioxidants in foods may harm the liver and lead to the development of cancer. The aim of the present study was to check the effect of curry leaves (Murraya koeneigii) extract on the thermal stability of ghee. Based on the peroxide and thiobarbituric acid (TBA) value determinations, it was observed that quality of ghee samples added with 1 % CLE during frying was significantly higher than that of control (ghee without antioxidant) and ghee added with 0.02 % BHA (a synthetic antioxidant). At 15 minutes of frying (180°C), the peroxide value was 3.615±0.24, 1.04±0.10 and1.07±0.02 mM O2/kg fat for the control, BHA added and CLE added ghee respectively and this increased to 8.23±0.23, 6.47±0.21 and 4.0±0.01 mM O2/kg fat after 60 minutes of frying, respectively. Findings suggested that CLE could be used as a source of natural antioxidants for imparting thermal stability to ghee during frying.
Keywords: Ghee, curry leaves, sensory characteristics, TBA value, DPPH, thermal stability, deep frying