Konjac glucomannan-based emulsion films with lysozyme-amyloid fibrils-chitosan complexes as dual-function antimicrobial emulsifiers for salmon preservation.

Abstract

Salmon is highly susceptible to spoilage due to microbial contamination and lipid oxidation, whereas active packaging can effectively delay quality deterioration during storage. This study employed chitosan-modified lysozyme amyloid fibrils (LC) as both antimicrobial agents and emulsifiers to prepare stable turmeric essential oil (TEO) Pickering emulsions with different LC-to-TEO volume ratios (1:1, 2:1, 3:1, 4:1), designated as TEOP1, TEOP2, TEOP3, and TEOP4 respectively. These emulsions were then incorporated into a konjac glucomannan (KGM) matrix to develop composite films. This study systematically evaluated the structural properties and freshness-preserving effects of composite films, using pure KGM film as the primary control and commercial polyethylene terephthalate (PET) film as the reference control. The results showed that strong interactions among components enhanced film properties: TEOP4/KGM reduced water vapor and oxygen permeability by 44 % (6.79 ± 0.59 g·mm/ (m2·day·kPa)) and 31 % (6.55 ± 0.36 g/ (m·s·kPa)). TEOP3/KGM exhibited optimal tensile strength (26.63 ± 1.45 MPa) and antioxidant activity (DPPH: 47.5 ± 2.6 %, ABTS: 96.3 ± 0.1 %), while TEOP4/KGM had highest elongation at break (68.35 ± 0.81 %). This suggests a trade-off, where a higher oil content (TEOP4) plasticizes the film, increasing flexibility but reducing strength. TEOP/KGM films inhibited E. coli, S. aureus, and L. monocytogenes, with the TEOP3/KGM and TEOP4/KGM formulations achieving 100 % inhibition rates. In salmon preservation, TEOP3/KGM best maintained appearance, pH stability, and reduced microbial growth/TVB-N, confirming its potential in aquatic product preservation.