Study on the physicochemical properties and antioxidant capacity of fish maw digestive juices from Pangasianodon hypophthalmus

ObjectiveThis study aimed to investigate the impact of digestion time on the digestibility, physicochemical properties, and antioxidant activity of Pangasianodon hypophthalmus fish maw.MethodsIn vitro digestion was performed with simulated gastric fluid and simulated small intestine fluid. The relative molecular weight, Zeta potential and amino acid composition of the digestive fluid were determined by gel permeation chromatography (GPC), amino acid analyzer and Zeta potentiometer, and the antioxidant capacity of the digestive fluid was evaluated.ResultsAfter the combined treatment of 1.5 h gastric fluid digestion and 4 h small intestinal fluid digestion, the digestibility, i.e. the total ratio of oligopeptide and polypeptide content, the total amino acid and the absolute value of Zeta potential of the digestible solution of P. hypophthalmus were the highest, which were 96.47%, 88.95 g/100 g and 21.65 mV, respectively. The highest antioxidant activity was obtained at this time with the 2,2-diphenyl-1-picrylhydrazine (DPPH) radical scavenging rate of 68.33%, 2,2'-biasido-bis-3-ethylbenzothiazoline-6-sulphonic acid (ABTS+) radical scavenging rate of 71.68%, hydroxyl radical scavenging capacity of 293.25 U/mL of digestion solution and ferrous iron ion reducing the capacity of 0.73 mmol/L.ConclusionP. hypophthalmus fish maw was best treated with a combination of gastric fluid digestion for 1.5 h and small intestinal fluid digestion for 4.0 h. The resulting digestive solution had better nutrition, stability, and antioxidant activity.