Study on the high viscosity and gel-prone properties of glycine-amidated pectin and its regulatory role on the freeze-thaw stability of sea bass surimi.

An ultra-low temperature (-5 °C) enzymatic method was employed to prepare glycine-amidated pectin (Gly-Pe) and evaluate its physicochemical properties and freeze-thaw protection mechanism in surimi. After glycine grafting (12.77 %), amide bonds disrupted pectin's crystalline structure and enhanced molecular chain flexibility. This transformation endowed Gly-Pe with superior properties: viscosity could reach up to 1000 times that of native pectin (Na-Pe) under specific conditions (pH 3, 6 % concentration, low shear rate) along with enhanced gel strength. In freeze-thaw protection applications, surimi containing Gly-Pe showed excellent textural properties after 4 freeze-thaw cycles, outperforming control and native pectin-treated groups. Although water holding capacity decreased from 95.22 % to 80.61 %, springiness retention reached 83 %, and chewiness and gumminess increased 3.4 and 3.85-fold respectively. This enhancement originated from Gly-Pe's unique mechanism in surimi of enhancing static load-bearing capacity by sacrificing partial dynamic rigidity, thereby achieving selective structural reorganization and providing foundation for developing novel frozen food protectants.