Preservation Effect of Protein-Based Composite Coating Solution from Highland Barley Distillers' Grains on Crown Pears.

Crown pears exhibit high susceptibility to rot and rapid deterioration, resulting in quality degradation and fruit softening. Edible coatings serve as an effective preservation technology to extend their shelf life. In this study, a composite coating solution was formulated using vitamin C (Vc), glycerol, ethanol, and gliadin derived from highland barley distillers' grains. The coating formulation was optimized via single-factor experiments and Box-Behnken response surface methodology, with crown pears' weight loss as the evaluation metric. The optimal composition comprised 19.86 mg/mL gliadin, 1.47% (v/v) glycerol, 2.49% (w/v) Vc, and 80.20% (v/v) ethanol, achieving a minimized weight loss of (3.30 ± 0.01)%. Treated pears coated with this optimized formulation were stored for 28 days. Preservation efficacy was evaluated through measurements of weight loss, decay rate, total number of colonies, firmness, titratable acid content, and polyphenol oxidase activity. Compared to the uncoated control group, the composite coating treatment significantly mitigated the decline in firmness, weight loss, and titratable acid content of crown pears. Furthermore, it effectively suppressed the increase in polyphenol oxidase (PPO) activity, decay rate, and total number of colonies, thereby extending the shelf life of the fruit.