Hydroxypropyl methylcellulose or soy protein isolate-based edible, water-soluble, and antioxidant films for safflower oil packaging.J Food Sci. 2021 Jan; 86(1):129-139.JF
Edible, water-soluble, heat-sealable, and antioxidant films were developed from hydroxypropyl methylcellulose (HPMC) or soy protein isolate (SPI) and applied as safflower oil packaging. A 0.1 or 0.2% DL-α-tocopherol acetate (VE) and 0 or 0.25% oleic acid were added into film formulations to provide antioxidant and hydrophobic properties, respectively, using a 23 factorial design. Films were analyzed for appearance, microstructure, water and oil sensitivity, mechanical properties, and antioxidant functionality. Subsequently, a completely randomized design was implemented for incorporating 2, 4, or 6% cellulose nanocrystals (CNCs, w/w dry weight polymer) for improving film mechanical and barrier properties. HPMC-based films achieved full dissolution in water at <55 °C under 5 min, while SPI-based films disintegrated in water up to 90 °C. Oleic acid significantly increased (P < 0.05) heat sealability of SPI film from 78 to 143 N/m and elongation at break from 36% to 88%, but decreased tensile strength and heat sealability of HPMC films by 55% and 41%, respectively. As safflower oil packaging, after 60 days of storage at 35 °C, oil contained in SPI-based pouch had the lowest peroxide values, 8.1 ± 0.9 mEq/kg. Based on barrier, mechanical, and antioxidant capacity evaluations, HPMC film with 0.1% VE and SPI film with 0.25% oleic acid and 0.1% VE were incorporated with CNC. SPI/CNC films did not show observable trends, but HPMC/2% CNC film exhibited significantly improved mechanical and barrier properties, with oxygen permeability of 5.0 mL mm/m2 day kPa. The developed films are a promising packaging alternative to decrease plastic waste, extend shelf life of lipid-based foods, and increase consumer convenience. PRACTICAL APPLICATION: Individually packaged, single-use pouches of sauce or oil are common for seasoning instant and frozen foods, creating unnecessary plastic waste. Edible, water-soluble packaging with antioxidant functionality would reduce plastic waste, extend shelf life by preventing oxidation, and increase consumer convenience. The biopolymeric films and pouches developed in this study have unique properties from water solubility across a wide range of temperatures, resistance to oil, high oxygen barrier, and good heat sealability, providing a variety of potential applications for promoting sustainable food packaging.