preparation of pectin from durian rind
The extraction method was modified from the combination methods described by McCready(1970)and Hokputsa et al. (2004).The durian rind (solid-liquid ratio:1:9,w/v) were gently stirred in a mind acid aqueous solution adjusted to pH 2 with 1M HCI.Then the solution was extracted at 90 for 4hr.The resulting slurries were filtered through cheese cloth and allowed to cool to room temperature(25C).Acifiied ethanol(4%HCI in 95%EtOH) was added in the ratio 1:4 (v/v) and kept for 1 hr. The mixture was centrifuged at 3000 rpm for 15min in a Bench Top Centrifuge(Kubota 5100,Fujioka,Japan)
The gel-like precipitate was collected and re-suspended in dis stilled water in a ratio of 1:4 (w/v).Then, the solution was rewashed twice with 95% ethanol(1:2,v/v) and centrifuge for 15 min(3000 rpm).The precipitate was collected and dried in a vacuum oven at 25C for 8 hr.The pectin was ground and sieved(mesh no.60)for further experiments.This pectin was designated as durian rind pectin orDRP