Carbon dots, cellulose nanofiber, and essential oil nanoemulsion from Torreya grandis aril added to fish scale gelatin film for tomato preservation

In this study, carbon dots (CDs), cellulose nanofibers (CNF) and essential oil nanoemulsion (EON) were extracted from the aril waste of Torreya grandis following nuts production. These three nanomaterials were formulated for the preparation of a composite film to be employed for postharvest tomato storage. Visual, microscopical and physicochemical properties of the prepared nanocomposite films were analyzed at different levels of CDs and CNF for optimization purposes. The UV absorption and antioxidant capacity of gelatin film with 10 % CDs (G/10CD) were enhanced compared with gelatin (G) film, concurrent with a reduction in water barrier capacity, water contact angle (WCA) and tensile strength (TS). Compared with G/10CD film, the WCA of G film after incorporation of 10 % CDs and 3 wt% CNF (G/10CD/3CNF) was significantly increased by 14.5°at 55 s. In contrast, TS increased by 1.26 MPa, as well as the significant enhancement in water barrier capacity. The above composite film mixed with EON (G/10CD/3CNF/EON) exerted further antimicrobial effects against Escherichia coli. G/10CD/3CNF/EON coating effectively extended tomato shelf life compared with the control group. Therefore, this new eco-friendly film presents several advantages of biodegradability, sustainability as well as multifunctional properties posing it as potential packaging material for food applications.