Gelatin/Quercetin Films Containing Mulberry Branch-Derived Dialdehyde Cellulose Nanocrystals: Film Properties and Blueberry Coating Evaluation

Abstract Mulberry branch-derived dialdehyde cellulose nanocrystals (DACNC) and quercetin were incorporated into gelatin (GEL) films to assess wet-state integrity and blueberry coating performance. Three independent DACNC batches had an aldehyde content of 1.215 ± 0.170 mmol/g. GDQ5 showed lower apparent water solubility and a lower reported swelling ratio than GEL under the tested conditions. Its film-forming solution showed transmittance below 4% at 365 nm and DPPH/ABTS radical-scavenging activity. A replicated five-treatment blueberry experiment found day-9 weight losses of 15.47 ± 0.75% for GDQ5 and 17.53 ± 0.63% for Control. The overall day-9 weight-loss treatment effect was not significant (p = 0.124). Visible-decay incidence was 53.33 ± 15.28% for GDQ5 versus 100% for Control, with lower GDQ5 incidence supported by block-adjusted, Holm-corrected comparisons. These findings support moderate, end point-dependent coating effects without establishing a specific preservation mechanism.