Stability of antioxidant and antibacterial properties in heated turmeric-chili paste and its ingredients

Turmeric-chili or yellow curry paste is a traditional condiment used in hot and sour curry soup consumed in Thailand and Southeast Asia. The effect of heat treatment on total phenolic content, antioxidant and antibacterial activities of the curry paste was investigated and results showed that the total phenolic content of the curry paste extract increased after heating at 80°C, 90°C and 100°C for 10, 20 and 30 min. The 2.2- diphenyl-1-picrylhydrazyl activity (DPPH) and ferric reducing/antioxidant power (FRAP) values of the heated curry paste extract were higher compared with unheated paste extract. The minimal inhibitory concentration (MIC) values of the heated paste extract on Staphylococcus aureus and Bacillus cereus were 2.616 and 5.232 mg/ml, respectively, and the minimal bactericidal concentration (MBC) values of the heated paste extract on S. aureus and B. cereus were 2.616 and 10.464 mg/ml, respectively. It was concluded that curry paste could retain its antioxidant activity even after heating therefore it could be valuable as a functional food.