Effect of Gelatin Concentration on Humidity-Dependent Film Properties and Coating Performance: A Case Study of Vacuum-Packaged Sliced Cooked Cured Pork Loin

This study aimed to evaluate the applicability of gelatin (GEL)-based edible coatings as a complementary preservation approach for vacuum-packaged sliced cooked cured pork loin (CCPL) during refrigerated storage (4 °C, 21 days), focusing on the effect of GEL concentration (5% vs. 10%) in coating-forming solutions on the properties of the resulting films and, subsequently, on coating performance. GEL films were character-ized and compared with a commercial polyamide/polyethylene (PA/PE) vacu-um-packaging film at 40–90% relative humidity (RH). Despite the more compact cryo-SEM microstructure of the 10%-GEL coating-forming solution, GEL films showed no significant differences in microstructure, crystallinity, or most physicochemical properties. Compared with the PA/PE film, GEL films exhibited a more compact and homogeneous structure, higher transparency and stronger UVB/UVC-blocking capaci-ty, lower oxygen permeability up to 60% RH (127.75–1231.25 vs. 4234.06–5056.72 cm³ μm m⁻² day⁻¹), and higher puncture strength up to 70% RH (9.12–15.24 vs. ~6.6 MPa). As RH increased, oxygen permeability increased in all films, while GEL films also ex-hibited increased moisture uptake and reduced mechanical strength. The 10%-GEL coating caused more pronounced color changes in CCPL. Both GEL coatings similarly impaired oxidative stability and microbial quality compared with the uncoated CCPL.