Monitoring the freshness of fish fillets by colorimetric gelatin composite film incorporated with curcumin extract

Abstract

This study aimed to develop a colorimetric intelligent gelatin composite film incorporated with curcumin to monitor fish fillets' freshness. Chicken skin gelatin composite film's sensing ability in NH3 environments in light transmission and color changes was studied and compared to bovine gelatin composite films. A spoilage test was also performed to evaluate the practical application of colorimetric intelligent films in monitoring the real-time freshness of fish fillets within 4 days of storage time. The results showed that both films possessed low ultraviolet (0.41–1.00) and visible light transmission values (0.16–2.69) while exhibiting good response towards NH3 by changing their color from yellow to reddish-orange, with more obvious color changes at higher relative humidity and response time. The films also showed distinct color changes from yellow to reddish-orange, which were correlated with changes in pH levels of fish fillets within 4 days of storage time. Hence, this indicates that chicken skin gelatin-curcumin composite films could be utilized in colorimetric intelligent food packaging as a visual indicator to monitor the freshness of fish fillets.