Edible thermochromic beads from flavonoid, fatty acid, and lecithin for smart packaging

Enzymatic browning and microbial growth are two natural phenomena that occur when fruits and vegetables are exposed to abnormal conditions, i.e., temperatures in the range of 12-22 °C, leading to their spoilage. Controlling the temperatures during the supply chain aims to optimize the product's shelf life. Irreversible thermochromic beads were fabricated using a simple extrusion technique containing fatty acid, lecithin, and anthocyanin solution-alginate. The pigmentation durability was adjusted based on electrostatic interactions, as evidenced by the reduction in dye leaching in the case of the produced bead at pH = 6 to less than 0.007 after 45 min. Characterization shows that the chosen combination of fatty acids and the quinonoid molecule is useful for producing thermochromic beads, with a color change at 12 °C-22 °C, from blue to purple. Using the prepared thermochromic beads in the supply chain of fresh-cut salad and brussels sprouts showed a great result for monitoring their freshness after 21 ± 1 min.