Designing of a New Intelligent Composite Film Based on Sodium Alginate/Gelatin/Shikonin Complex for Tracking Meat Freshness

Abstract

We developed a new colorimetric smart indicator film through the incorporation of shikonin into a composite film of sodium alginate (SA) and gelatin (Gel) using the casting technique. Results showed the fabricated composite film had better mechanical properties than monofilms. The incorporation of shikonin improved the physical properties, gas sensitivity, and thermal stability of the SA/Gel based film. Fourier Transform Infrared Spectroscopy (FTIR) spectrums further supported the superior compatibility of shikonin with the composite film. Additionally, the indicator films spiked with shikonin showed good pH-responsive sensitivity with color changing from red (pH 2) to blue (pH 12). Then the indicator film was  employed to track variations in pork freshness by establishing a correlation between pork pH, chromaticity, total volatile basic nitrogen (TVB-N), and the alteration in color of the indicator film.  This smart composite film has a great potential for food packaging applications, especially for monitoring the freshness of pork.

Keywords: Composite film, Color indicator, Shikonin, pH-responsive, Meat freshness