Performance of fish gelatin coating incorporated with liquid smoke in tilapia fillet preservation

Abstract

This study investigated the preparation and characterization of an active edible film made from fish gelatin, with the addition of liquid smoke at varying levels of 0 %, 5 %, 10 %, and 15 % (v/v). The films were characterized for their antimicrobial activity, water resistance, physical, optical, and barrier properties. Furthermore, film performance in extending the shelf life of Nile tilapia fillets (Oreochromis niloticus) was evaluated through a coating application. The freshness degradation of the fillets stored under refrigeration for 12 days was assessed using microbial and biochemical parameters including the total plate Count (TPC), total volatile basic nitrogen (TVB-N), thiobarbituric acid reactive substances (TBARS), and pH. The results showed that the addition of liquid smoke not only imparted antimicrobial properties to the gelatin film but also improved its water resistance, and ability to inhibit water vapor transmission. These enhancements in functional properties were primarily attributed to the presence of phenolic compounds, which provide antibacterial effects and facilitate crosslinking formation within the fish gelatin polymer matrix. The fish gelatin coating incorporated with liquid smoke effectively retarded the growth rate of spoilage bacteria and reduced biochemical changes caused primarily by oxidation, thereby extending the shelf life of the tilapia fillets from 8 days up to approximately 13–15 days, with the 10 % liquid smoke film identified as the most effective treatment. These findings highlight the potential of fish gelatin coatings incorporated with liquid smoke for commercial application, especially for retailers of fresh products.