Study on bioactive compound degradation from belimbing buluh (averrhoa bilimbi)

Averrhoa bilimbi Linn. are type of family Oxalidaceae that had a common name such as bilimbi, belimbing buloh and balimbing. They have an excellent source of bioactive compounds such as flavonoid, phenolic and antioxidant included oxalic acid, vitamin C, tannins also minerals. A. bilimbi, has been widely used in traditional medicine since gives high good impact to humankind for cured disease such as cough, cold, itches, boils, rheumatism, syphilis, diabetes, whooping cough and hypertension. However, this active compound will reduce its value during undergo heating and drying process especially when exposed to high temperature. Since bioactive compounds are unstable when it exposed to heat, the product will become low in the nutritional value. Therefore, it very important to understand the thermal degradation of A.bilimbi to maintain the product quality and produce nutritional product that can used for human health, and hence this is the objective of this work. Extraction of A. bilimbi fruit were performed using 50% concentration methanol as a solvent. Then, the heat treatment was performed using a metal tube containing A. bilimbi extracts at various temperature and time exposure. Total flavonoids (TFC) and phenolic (TPC) content were analyses using colorimetric assay. Meanwhile, the free-radical scavenging (antioxidant) activity was measured using 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. All analysis was performed using a calibrated ultraviolet-visible spectroscopy (Hitachi U-1800, Japan). TPC and DPPH were found to decrease relatively as the heating time prolonged and temperature increased were, from 885 to 877 mg GA/100 g Averrhoa bilimbi and from 42 to 40 % after 120 minutes heat treatment respectively. However, TFC increased significantly with temperature and heating time were from 852 to 2133 μg/100 g A.bilimbi. From this study, it showed that a long period of heat treatment of A. bilimbi at a relatively high temperature destroy the overall antioxidant activity. Therefore, the overall antioxidant activity of A. bilimbi should be enhance to minimize the degradation of natural antioxidant during thermal processing