Contribution of Quasifibrillar Properties of Collagen Hydrolysates Towards Lowering of Interface Tension in Emulsion-Based Food Leading to Shelf-Life Enhancement

Abstract

This study was conducted to decipher the mechanism of emulsion-based food stabilization by fish-derived collagen hydrolysate. Collagen type I was isolated from seven fish processing by-products with yields ranging from 9.15 to 92.38%. The isolated samples had a mass of 110–120kDa and eluted at 30.44% NaCl in ion-exchange chromatography. The collagen samples were enzymatically digested to obtain collagen hydrolysate (CH) with mass <6kDa. The seven CH samples were subsequently screened for surface activity. CH obtained from Pacu skin and Tilapia bones exhibited more than 80% solubility over a wide pH range, zeta potential greater than +50mV, moisture retention up to 92–96%, emulsification activity of 53–70 m2g−1, and emulsion stability of 62–85min, and successfully increased the emulsion stability of a drug by 14 times. Both CH samples were able to retain the emulsion properties of butter and chocolate sauce for 25 weeks and did not show any cytotoxic effect on leukocytes and Vero cells. Structural studies revealed that the CH peptides existed in polyproline-II conformation that assembled to form a vast quasifibrillar network. Sequence analysis through tandem mass spectroscopy revealed that the peptides could be classified into multiple groups depending on the distribution of hydrophilic/lipophilic residues (H/L). The surface activity of the CH was found to be dependent on (1) small size and a wide array of H/L ratio, (2) abundance of hydroxyproline, and (3) assembly of the peptides in the emulsion interface to form a mimic-helix–based quasifibrillar network which ensured optimal orientation and subsequent interaction with multiple phases.