Development and Characterization of Active Pectin–Curdlan Biopolymer Films with Cannabigerol (CBG) Oil as Innovative Materials with Plant Metabolism–Stimulating Properties and Potential to Extend the Postharvest Shelf Life of Blackberries (Black Satin) Fruits

In the present study, the physicochemical, mechanical, and functional properties of biodegradable pectin/cudlan gum polysaccharide films with CBG oil were evaluated. In these studies, the TS values for the films ranged from 8.50 MPa to 14.80 MPa. The EB values ranged from 33.06% to 39.07%. The WVTR ranged from 13.7 to 9.51 g/m2 d. In all the films tested, the change in the L* parameter did not change significantly statistically (p ≥ 0.05). In films with low CBG content (0.125F, 0.25F, 0.35F), L* remained stable, which indicated their resistance to darkening. However, film 0.5F was an exception, as it showed a decrease in L*, suggesting darkening or photodegradation processes. CBG films reduced mold growth, water loss, color degradation, and anthocyanin content in stored fruit, especially films with a content of 0.125F–0.35F, while higher concentrations (0.5F–0.75F) could cause pro-oxidative effects. Soil application of the film showed that moderate CBG concentrations (0.25F–0.35F) increased the content of chlorophyll, carotenoids, and phenols, indicating biostimulating potential, while the highest concentrations could cause oxidative stress. At the highest CBG concentration (0.75F), the carotenoid content decreased to 0.054–0.113 mg·g−1 FW. At higher concentrations of active substances in the film (0.5F and 0.75F), stabilization or a decrease in O2•− levels was observed, which may indicate the effective activation of protective mechanisms leading to the neutralization of excess free radicals.