| dc.description.abstract | There are growing interest of searching natural replacements for synthetics antioxidants since antioxidants from nature sources are considered as safe, nutritional and have therapeutic effects. This has led to the antioxidant evaluation on various plants, including Hibiscus sabdariffa. Ultrasonic-assisted extraction (UAE) was used for extraction of antioxidant and phenolic compound of Hibiscus sabdariffa plant part. Antioxidant activity was tested using 2,2′-diphenyl-1-picrylhydrazyl (DPPH) methods and total phenolic compound from extracts was tested using Folin-Ciocalteu reagent test. Selected part of Hibiscus sabdariffa, was optimized to obtain maximum yield of antioxidants according to three parameters (extraction temperature, ultrasonic frequency and extraction time). The best parameters to be used to extract antioxidants from the selected part of Hibiscus sabdariffa, was decided using Response Surface Methodology (RSM) based on three-factor, three-level central composite design (CCD). The result showed good fit with the proposed model for antioxidant extraction (R2=0.9516). Optimized extraction condition for antioxidant activity for Hibiscus sabdariffa calyces at a ratio of solid to liquid 0.025g/mL and 55% methanol concentration, was 62.5℃, 50 min and 32 kHz. | en_US |
