Effect of a poly(vinyl alcohol)-based coating containing CaCl₂ and sorbic acid on apple quality during long-term refrigerated storage (2024-2025 season)

ITMO University, Saint Petersburg, Russia

Abstract

The effect of poly(vinyl alcohol) (PVA)-based coatings on the storage stability of Jonathan and Renet Simirenko apples during long-term refrigerated storage was studied. The experimental coating was PVA 2.5% + CaCL₂.0% + sorbic acid 0.2% (Var. 3). A commercial edible coating, NanoSkin (Var. 5), was used as an industrial benchmark, while uncoated fruit served as the control. Storage was carried out during the 2024–2025 season with sampling from November to May. Commercial quality (marketable yield, defect categories and weight loss), respiration rate, internal gas composition (CO₂ and O₂), and changes in carbohydrate profile and ascorbic acid content were assessed. By May, Var. 3 increased marketable yield by 13.1 percentage points for Jonathan and by 15.6 percentage points for Renet Simirenko compared with the control, while reducing natural weight loss (Jonathan: 4.9% to 2.5%; Renet Simirenko: 3.0% to 2.0%). Coatings reduced the respiration peak observed in the control in March-April, established a modified internal gas regime with higher CO₂ and lower O₂, and improved retention of total sugars, sucrose and ascorbic acid. The results indicate that the PVA-CaCL-sorbic acid formulation is a practical technological tool for reducing storage losses in apples.