Effect of heat treatment on antioxidant and antibacterial activity of Kaempferia galanga L. extract

Kaempferia galanga L. is a rhizome plant that is rich in health benefits, it can be processed into a herbal drink by heating. Meanwhile, heating is carried out to kill certain pathogenic bacteria present in a product with a minimum loss of nutrients and to maintain the bioactive compounds. Therefore, this study aimed to evaluate the effect of heating using temperatures at 60°C and 80°C for 10, 20, and 30 mins on the antioxidant and antibacterial activity of K. galanga extract. The extraction process was carried out using the sonication method with a frequency of 35 kHz for 20 mins and a water-solvent ratio of 1:2 (b/v). The extract was heated at 60°C and 80°C for 10, 20, and 30 mins, and then antioxidant and antibacterial activity were analyzed. The results showed that heating at 60°C and 80°C for 10, 20, and 30 mins significantly decreased the antioxidant and antibacterial activity. Furthermore, the heating using a temperature of 60°C for 10 mins can reduce microbial contamination by 3 logs compared to the control sample and still maintain the total phenolic and flavonoid, antioxidant activity, ferric reducing antioxidant power, ferrous ion chelating, and antibacterial activity of K. galanga water extract.