Application of Buckwheat Starch Film Solutions as Edible Coatings for Strawberries: A Proof-of-Concept Study

The present study serves as a proof-of-concept of our previous work, as the buckwheat (BW) starch film solutions are applied as edible coatings on strawberries and as film packaging materials for strawberry preservation. The BW starch film solution was modified with citric acid (CA) for cross-linking and chitosan nanoparticles (CNP) and by ultrasound application. We tested four formulations for coating: uncoated (negative control), BW starch only (positive control), BW starch with CA and CNP, and ultrasonicated BW starch with CA and CNP. Results demonstrated that BW starch coating, with or without modifications, had positive effects in preserving strawberry quality during 14 days of refrigerated storage at 4 ± 1 °C and 82 ± 1% RH. Coating with only BW starch better suppressed weight loss; a 16% reduction in weight loss was observed compared to the uncoated counterpart at day 14. On the other hand, modifications of coating formulation played a role in preserving different fruit quality parameters. BW starch with CA and CNP had improved textural properties and reduced signs of decay. A 56% reduction in the decay index (DI) was observed in the coated fruits compared to the control. Starch coating restricted chemical changes and maintained total phenolic content (TPC) during storage. TPC in ultrasound-treated solution-coated fruits was the highest, 1.3 mg GAE/g, at the end of the storage. As packaging materials, BW starch films effectively reduced moisture loss from packaged strawberries. The future scope of the study lies in optimizing film solutions for various applications and in understanding enzymatic activities in BW starch-coated fruits.