Antioxidative activity of Malaysian herb extracts in refined, bleached and deodorised palm olein: accelerated oxidation study
2007
Nor Aini I. | Fatihanim M. N. | Razali I. | Suhaila M.
Malaysian herbs such as curry leaves (Murraya koenigii), kaffir lime leaves (Citrus hystrix), pandan leaves (Pandanus amaryllifolius) and turmeric leaves (Curcuma longa) are often used as flavouring in Malaysian food. They may contain various phytochemicals, which may act as antioxidants or prooxidants. In order to investigate theantioxidant capacity, the extracts were subjected to antioxidant tests. For accelerated oxidation study, the ethanolic extracts were added to refined, bleached and deodorized (RBD) palm olein and heated to 180°C from 0 to 32 hours. The polyphenol content wasobserved highest in turmeric leaves (78.005mg/g), followed by curry leaves (73.471mg/g), kaffir lime leaves (69.486mg/g) and pandan leaves (68.273mg/g). In DPPH assay and linoleic acid model system, the antioxidative activity followed the order- Turmeric leaves> Curry leaves> Kaffir lime leaves> Pandan leaves. However, inheated oil, the best activity was observed in sample treated with curry leaves and kaffir lime leaves at 0.4% with activity comparable to BHT (p<0.05). Based on Oxidative Stability Index (OSI), each herb are capable of retarding oxidation significantly even at 0.1% compared to BHT (p<0.05). This indicated that Malaysian herbs have big potential as excellent heat- stable antioxidants and could be good alternatives to replace existing synthetic antioxidant.
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