When Color Speaks Freshness: Red Cabbage Anthocyanins as Smart Biodegradable Films for Next-Gen Meat Safety
Elysa Grace Edward, Rovina Kobun

1Faculty of Sustainable Agriculture, Universiti Malaysia Sabah, Sandakan, Sabah, Malaysia
2Food Security Research Lab, Faculty of Food Science and Nutrition, Universiti Malaysia Sabah, Kota Kinabalu, Sabah, Malaysia

Abstract

This study explores the colorimetric response and spectroscopic properties of red cabbage (Brassica oleracea) anthocyanins across the full pH range (1-14) using buffer solutions adjusted with acetic acid, sodium thiosulfate, HCl, and NaOH. Anthocyanins were extracted and purified prior to experimentation, then introduced into each buffer, resulting in a vivid spectrum of color changes: red in acidic conditions, purple at neutral pH, and blue to yellow in alkaline environments, consistent with their known pH sensitivity. These transitions were visually observed and further characterized by UV-Vis spectroscopy, which revealed clear, pH-dependent shifts in absorption maxima corresponding to different anthocyanin structures. The study confirms that red cabbage anthocyanins are reliable, natural pH indicators, showing distinct and reversible color changes that can be easily detected by the naked eye. Their application is particularly relevant for monitoring freshness in perishable animal-derived foods such as meat, where spoilage is closely linked to pH changes. Incorporating anthocyanins into smart packaging films offers a low-cost, biodegradable, and consumer-friendly approach to real-time freshness detection. By improving food safety, reducing waste, and replacing synthetic indicators with natural alternatives, this work supports sustainable animal agriculture and aligns with the UN Sustainable Development Goals (SDGs).

Keywords: Red cabbage anthocyanins, natural pH indicator, colorimetric response, meat freshness, UV-Vis spectroscopy

Topic: Animal Product Technology