Raw Trout Fillets Coated with Carvacrol-Loaded Gelatin Nanofibers: Changes in Microbiological, Texture, and Odor Compounds During Cold Storage

Abstract

Carvacrol-containing gelatin nanofibers were successfully produced, characterized, and applied on farmed trout fillets as coating material. Scanning electron microscopy (SEM) images revealed that the presence of carvacrol increased the average fiber diameter from 152.3 to 217 nm and less droplet formation was observed after carvacrol addition. Young’s modulus and stability of the nanofibers were found to increase with the increasing weight percentage of carvacrol. The applied nanocoating treatment positively slowed the growth of bacteria, yeast, and mold throughout 9 days of storage (p < 0.05). The decrease in hardness was slower in the gelatin nanofibers containing the 7.5% carvacrol (GLC7.5)-coated group compared to the uncoated group in the first 5 days (p > 0.05). A total of 14 volatile organic compounds (VOCs) were identified by gas chromatography-mass spectrometry (GC–MS) in the uncoated and GLC7.5-coated samples as volatile indicators of flavor deterioration. Volatile substances that cause an off-flavor in the fillets were found at a lower rate in the GLC7.5-coated group and showed higher sensory odor scores. The most important aroma compounds identified in the samples were dimethyl disulfide (DMDS) (garlic-like), dimethyl trisulfide (rotten egg), 3-methyl butanoic acid (cheesy), phenol (phenolic), and 1H-indole (fecal). Additionally, carvacrol (spicy) was found to be an important contributor of odor to meat with a GLC7.5 coating. The results showed that carvacrol-loaded nanocoatings have antimicrobial and antifungal properties that affect the formation of volatile compounds in fish meat. Therefore, the nanocoating technique could be useful in preventing spoilage and boosting the odor attributes of fresh fish products.