Protecting anthocyanins of postharvest blueberries through konjac glucomannan/low-acyl gellan gum coatings contained thymol microcapsule during low-temperature storage

In order to protect the anthocyanins in blueberries during low-temperature storage, TMs/KGM/LAG (TKL) coatings were developed by composite thymol/β-cyclodextrin (β-CD) microcapsules (TMs), konjac glucomannan (KGM), and low acyl gellan gum (LAG). The results showed that the TMs prolonged the release of thymol for at least 30 d. The TKL was effective in maintaining the color of blueberry skin by regulating the activities of key enzymes for anthocyanin synthesis and degradation. Among the different treatment groups, TKL60 (thymol concentration of 60 mg/L) was the most effective in protecting anthocyanin. At 42 d of storage, the TKL60 group showed the highest anthocyanin levels of malvidin-3-O-galactoside (718.38 μg/g), delphinidin-3-O-galactoside (343.75 μg/g) and cyanidin-3-O-galactoside (40.67 μg/g). In addition, TKL60 treatment still showed good maintain the qualities of blueberries (weight loss, decay, hardness and TSS). Thus, this study provides a new approach to protect anthocyanin in blueberries after harvest during low-temperature storage.