Double-layer indicator films aided by BP-ANN-enabled freshness detection on packaged meat products

Abstract

Anthocyanins can be used as a pH-sensitive material to indicate freshness of packaged meat products, which can nevertheless be easily degraded, the pigments should be encapsulated in an appropriate matrix. In this study, raspberry anthocyanins were proposed as a novel freshness indicator and were incorporated into low-acyl gellan to improve its stability. Chitosan was used to form an outer layer of a double-layer indicator film. The results showed that the anthocyanin had response to the change of pH value, the double-layer indicator film had strong mechanical properties, low water vapor permeability and good structural compatibility, and the stability of raspberry anthocyanin was improved. To explore the applicability of the developed film system, pork patties and fish balls were selected as test meat products. Back propagation artificial neural network model was established using color of the films as the input and total volatile nitrogen (TVB-N) content as the output. TVB-N contents of pork patties and fish balls increased to spoilage levels after 6- and 3-day storage at 4 ℃; color of the films changed from pink to brown and finally to dark green as storage proceeded. Neural network model well predicted the freshness of packaged meat products based on color change of the films, with R2 of 0.94–0.98.