The by-products from Pangasius hypophthalmus in fishery processing plants in the Mekong River Delta, Vietnam is very abundant but not being fully utilized. Calcium-binding is one of the most important biological functions of FPI which derived from Pangasius hypophthalmus byproducts. This opens up prospects for using of FPI from catfish byproducts to manufacture the products enhancing human calcium absorption. This study focused on optimization of experimental factors during nano-filtration (NF). The separation has proceeded by using 5 kDa GE-5-DL spiral NF membrane at difference operated conditions and optimized using response surface methodology (RSM) to obtain FPI from Pangasius hypophthalmus by-products with the highest possibility of calcium-binding. Results showed that the highest calcium-binding of FPI is 31.54 (mg Ca+2/g FPI) with the NF conditions: temperature 450C, input flow’s velocity 29 l/h; operating pressure 11 bar. The protein percentage by molecular weight of FPI as follows: <3 kDa: 82.88%, from 3 kDa to <7 kDa: 17.12 %. Type the links between Ca+2 and proteins in FPI: 93.52% binding through EF hand structure; 1.18% as hydrogen bonding through water bridge; 3.24% as electrostatic links between Ca+2 with the starting amino acid of proteins
Keywords: FPI, GE-5-DL, Pangasius hypophthalmus by-products, calcium-binding, optimization (RSM).