Development of a Colorimetric Intelligent Film Based on Biodegradable Polymers Incorporated with Hibiscus sabdariffa Anthocyanins for Monitoring Salmon Fish Spoilage

Abstract

Fish is one of the most perishable foods, and suitable packaging increases its shelf life. In this research, the colorimetric indicators based on stabilized anthocyanins of Hibiscus sabdariffa in gluten and carboxymethyl cellulose film were designed to monitor the chemical and microbial characteristics of salmon fish at 25 °C for 16 h and at 4 °C for 12 days. The fresh fish had a light color, but the fish color was critically increased at the end of storage (p < 0.05) with the increase in pH and spoilage. Moreover, the color of the intelligent film changed, indicating fish spoiling. The visual color changes from red to green were caused by the release of volatile nitrogen compounds during salmon spoilage, which are absorbed by gluten-CMC-anthocyanin films. The pH, volatile nitrogen compounds (TVBN), peroxide value, thiobarbituric acid (TBARS), trimethylamine (TMA), and the count of mesophilic and psychrophilic bacteria were increased during storage (p < 0.05). At the end of the storage, the mesophilic bacteria reached 8.26 and 8.65 log CFU/g at 4 and 25 °C, respectively. Therefore, at the ambient conditions, fish was acceptable for less than 12 h, and at the refrigerator, the mesophilic bacteria did not exceed the standard limit for 6 days. In conclusion, the colorimetric film based on gluten-CMC-Hibiscus sabdariffa anthocyanins can be used as a suitable indicator for continuous monitoring of salmon fish spoilage.

Graphical Abstract