Development of a Smart Bio-based Colorimetric Indicator Infused with Black Carrot Anthocyanins for Real-Time Freshness Tracking of White Button Mushrooms (Agaricus bisporus)

Abstract

White button mushrooms (Agaricus bisporus) are highly perishable due to their high moisture content, rapid respiration rate, and lack of protective cuticle, which leads to rapid deterioration in texture, color, and microbial quality. Conventional quality assessment methods such as physicochemical and microbiological testing are time-consuming, destructive, and not applicable for real-time monitoring across the supply chain. This creates a pressing need for intelligent, non-destructive, and cost-effective tools that can provide real-time freshness information. This study introduces a novel pH-sensitive freshness indicator for real-time quality monitoring of white button mushrooms (Agaricus bisporus). The indicator was developed by immobilizing anthocyanin extracted from black carrot, a natural food-grade additive, onto Whatman-42 filter paper. Its performance was assessed for colorimetric response, structural integrity, and mechanical stability. Black carrot anthocyanins exhibited a distinct color shift from light pink (acidic pH) to spruce blue (alkaline pH) across the range of pH 2–10, demonstrating inherent pH sensitivity. Field emission scanning electron microscopy confirmed a porous microstructure, verifying successful physical immobilization without chemical modification. Fourier transform infrared spectroscopy highlighted hydrogen bonding as the immobilization mechanism, and X-ray diffraction revealed minor crystallinity reduction. Mechanical testing demonstrated unaffected tensile strength. The indicator was tested on fresh mushrooms stored in biodegradable trays under ambient (25 ± 1 °C) and refrigerated (5 ± 1 °C) conditions. The indicator’s performance was validated through colorimetric monitoring, physicochemical analysis, volatile organic compound profiling, and principal component analysis (PCA). The indicator effectively distinguished freshness stages as “fresh,” “still fresh,” and “spoiled” based on visually discernible color changes. Statistically significant correlations (p < 0.01) were observed between the indicator’s response and mushroom quality parameters, with weight loss (r = 0.93) showing the strongest correlation. PCA further confirmed three distinct freshness phases: fresh (days 1–4), still fresh (days 6–8), and spoiled (days 10) with distinct classification among the clusters correlated with change in color of the indicator. This freshness indicator offers a promising, sustainable solution for intelligent packaging applications, with significant implications for improving food quality control, reducing postharvest losses, and enhancing transparency in the food industry.