Development of Smart Colorimetric Sensing Films Carbohydrate-Based with Soybean Wax and Purple Cauliflower Anthocyanins for Visual Monitoring of Shrimp Freshness

Novel pH-colorimetric intelligent films were designed from agar and methylcellulose matrix (AM) with soybean wax (SBW) in several percentages (5, 10, 15, and 20%w/w) combined with purple cauliflower (CF) anthocyanins as an indicator of the shrimp freshness at 4 °C and 25 °C of storage temperatures. The color was observed in a mixture of AM/CF anthocyanins with SBW (hydrophobic), which completely converted in pH acidity 2–6 and somewhat in pH alkalinity 7–12, equivalent to the color seen when exposed to ammonia vapors 100 mmol/L. The spectroscopic analysis indicated that SBW was successfully settled into the AM/CF film. The homogenized SBW films enhanced the mechanical, thermal, antioxidant, control release of the anthocyanins and physical properties, significantly reducing water vapor permeability in AM/CF/15%SBW. Remarkably, SBW films showed total protection for UV–Vis light and a beneficial decline in visible light. Lastly, pH-colorimetric film validity to indicate the freshness/spoilage of a model food (shrimp) was confirmed.