Effects of microencapsulated ε-Polylysine hydrochloride on quality and microbial indicators of salted bamboo shoots

Salted bamboo shoots are susceptible to microbial spoilage and quality deterioration, while ε-polylysine hydrochloride (ε-PL·HCl) suffers from poor stability and hygroscopicity. To address this, ε-PL·HCl-loaded microcapsules were fabricated via complex coacervation using soy protein isolate (SPI) and chitosan (CS) as wall materials. The resulting microcapsules achieved an encapsulation efficiency of 98.63% and exhibited enhanced thermal stability, with a 25-30 °C increase in decomposition temperature compared with free ε-PL·HCl. SEM and XRD supported the incorporation of ε-PL·HCl into the SPI-CS matrix, while in-vitro release studies demonstrated sustained-release behavior in an aqueous medium. During 13 days of storage of salted bamboo shoots, ε-PL·HCl microcapsules (ε-PL·HCl-MCs) maintained hardness at approximately 300 N, reduced total bacterial counts to below 1 × 10⁷ CFU/g, delayed the decrease in b* value (yellowness), and slowed the decline in pH. This SPI-CS-based delivery system provides a promising strategy for natural antimicrobial preservation.