Development and Evaluation of Corn Starch Films Incorporating Red Cabbage Extract as Non-Contact Freshness Indicators for Minced Chicken

The present study investigates the development of corn starch-based films incorporating red cabbage extract (RCE) as natural colorimetric freshness indicators for minced chicken. This work addresses the need for safe, natural, and non-contact freshness indicators by integrating anthocyanin-rich RCE into corn starch films and evaluating their response to spoilage-related pH changes in poultry. Although anthocyanin-based films have been previously reported, their application as non-contact indicators for minced chicken—validated simultaneously through microbiological, physicochemical, and volatile compound analyses—has received limited attention. Corn starch films (CSFs), without and with RCE at different concentrations, were prepared and evaluated for thickness, mechanical properties, moisture content, and water solubility. The colorimetric response of CSF + RCE specimens to pH changes associated with meat spoilage was evaluated under refrigerated storage. The spoilage of minced chicken was independently monitored through microbiological analyses [total viable count (TVC), Pseudomonas, Brochothrix thermosphacta, Enterobacteriaceae, lactic acid bacteria (LAB), yeasts and molds] and physicochemical measurements [pH, total volatile basic nitrogen (TVB-N) and volatile compound profile]. Both microbiological and physicochemical indicators confirmed the onset of spoilage between the 5th and 7th days of storage, with unacceptable pH, TVB-N, and microbial levels being observed on the 7th day. The films exhibited visible though limited color changes in response to spoilage-related pH shifts. While the narrow pH range of poultry spoilage constrained the intensity of visual differences, the results demonstrate the potential of RCE-based films to be considered preliminary non-contact indicators and to support more sustainable food systems by enabling real-time freshness monitoring and potentially reducing unnecessary food waste. This study also highlights the need for future work incorporating objective colorimetric measurements (e.g., CIELab) and structural characterization to optimize indicator sensitivity.