Preparation of multifunctional carboxymethyl cellulose-based films incorporated with chitin nanocrystal and grapefruit seed extract.

Chitin nanocrystals (ChNC) were isolated from shrimp shells powder using acid hydrolysis and ammonium persulfate methods. Multifunctional carboxymethyl cellulose (CMC) composite films were prepared by adding ChNC and grapefruit seed extract (GSE), and their effects on the optical, mechanical, water vapor barrier, and antibacterial properties of CMC film were investigated. The isolated ChNC had a needle-like structure with a length of 340-370 nm and a diameter of 18-20 nm depending on the isolation method. The CMC films prepared with ChNC and GSE were transparent with high UV barrier properties. The addition of GSE reduced the strength (TS) and stiffness (EM) of CMC films by 10.4% and 30.3%, respectively, while the flexibility (EB) increased by 17.7%. However, when the ChNC was added, the TS and EM of CMC film increased by 19.7% and 58.7%, respectively, and the EB remained the same. The addition of ChNC reduced the water vapor permeability (WVP) of the CMC film by 27%. CMC films containing GSE also showed strong antibacterial activity against foodborne pathogenic bacteria, E. coli and L. monocytogenes.