Multifunctional Indicator Films of Polyvinyl Alcohol/Guar Gum (Anthocyanins and Houttuynia Essential Oil Pickering Emulsion) Aided by Residual Networks for Monitoring Pork Freshness

This study developed a multifunctional freshness indicator film based on black wolfberry anthocyanins (BWA) and a Houttuynia essential oil Pickering emulsion for monitoring pork freshness. The film was fabricated using a polyvinyl alcohol/guar gum blend system via a casting method, followed by screen-printing of a chitosan-stabilized Houttuynia essential oil Pickering emulsion onto its surface. The film showed improved mechanical strength (tensile strength up to 32.35 MPa) and ammonia-responsive color change from purplish-red to bluish-green during 4 °C pork storage, correlating with TVB-N (17.73 mg/100g) and TVC (5.98 lg CFU/g) by day 6. Structural analyses (SEM, FTIR, XRD) confirmed hydrogen bonding and enhanced film compactness. A ResNet18 model trained on 305 film images achieved 97.3% classification accuracy and was integrated into a PyQt5-based visual platform. This work integrates natural pigments, antibacterial Pickering emulsions, and deep learning for real-time meat freshness monitoring. However, the film's color stability under prolonged storage and its sensitivity to environmental humidity require further optimization. Future studies should focus on scaling up production and validating the system for diverse meat products under varying storage conditions.