Enhancing Functional Properties of Edible Films through the Combined Ultrasound-Assisted Extraction and Cold Plasma Treatment of Moroccan Pumpkin Seeds (Cucurbita pepo) Protein Isolates

Abstract

This study evaluates the effectiveness of combining ultrasound-assisted extraction and cold plasma treatment to improve the mechanical, barrier, and functional properties of edible films made from Moroccan pumpkin seed protein isolates. Ultrasound-assisted extraction was conducted at 20 kHz and 45–50% power with a 1:10 ratio of pumpkin seed sample to alkali solution for 30 min. The process yielded a protein-rich isolate (87.10%) with high solubility at pH 9 and good absorption capacities for water (1.80 ± 0.06 mL/g) and fat (3.88 ± 0.08 mL/g) and a gelling capacity of 12%. The films produced from these isolates demonstrated promising functional properties for food packaging applications. Further improvement of the film properties was achieved through cold plasma treatment using a 40 kV pulsed DC power supply at 56 kHz for 0, 10, 20, and 30 min. This treatment stabilized the moisture content (10.79–11.16%) and significantly reduced swelling (from 204.87% to 159.09%), suggesting enhanced barrier properties that could extend food shelf life. Although transparency decreased slightly (from 0.94 to 1.20), the films retained acceptable visibility and exhibited promising ultraviolet barrier properties, making them suitable for packaging light-sensitive food products.