Application of CFS-Loaded CMC/GEL Spray Coating for the Small Fruit Blueberries Preservation.

Blueberries are highly susceptible to decay due to mechanical damage such as bruising or impact. Traditional postharvest preservation methods such as brush and dip coating generate solvent waste, incur high labor costs, and may also leave visible brush marks. Moreover, due to their "one-by-one" coating process, which lowers the processing efficiency, these traditional methods are not suitable for small fruits such as blueberries. To solve this problem, a functional spray was developed in this work using gelatin (GEL) and sodium carboxymethyl cellulose (CMC) as the matrix, and a cell-free supernatant (CFS), produced by the centrifugation of lactic acid bacteria fermentation broth, was used as the active ingredient. Microstructural (SEM), intermolecular interaction (FTIR), and crystal structure (XRD) analyses of a CFS/CMC/GEL composite film demonstrated that the components of the functional spray had good compatibility. Moreover, this film had a greater water vapor permeability (WVP), reduced transmittance, and enhanced light-blocking properties compared with a CMC/GEL film. The 100% CFS/CMC/GEL functional spray exhibited improved antimicrobial performance against