Rice germ flour–carrageenan edible films as active packaging for instant noodle seasoning powder: Physicochemical, mechanical, and antioxidant properties

Instant noodle seasoning is commonly packaged in non-recyclable multilayer sachets and is susceptible to lipid oxidation. This study developed edible films from rice germ flour and κ-carrageenan with dissolvable and antioxidant-active properties and investigated the effects of glycerol concentration (20, 30, and 40% w/w) on their physicochemical, mechanical, and antioxidant properties. Among three Thai rice cultivars, Riceberry (RB) germ flour exhibited the highest flour yield, anthocyanin content, and antioxidant capacity and was selected for film development. Anthocyanin content was positively associated with ferric reducing power, supporting a contribution of anthocyanins to antioxidant activity. Increasing glycerol concentration increased elongation at break from 10.05 to 19.55%, while decreasing Young’s modulus from 995.65 to 599.95 MPa and glass transition temperature from 61.0 to 55.3°C. Tensile strength and water vapor permeability were not significantly affected. FTIR analysis indicated no substantial alteration in the hydrogen-bonding environment, suggesting that glycerol redistributed hydrogen bonding within the film matrix. At 90°C, RB40 exhibited the shortest dissolution time (3.14 min), whereas the extent of dissolution decreased from 78.92 to 67.14%, indicating that glycerol concentration independently influenced dissolution rate and extent. Compared with the control film without rice germ flour, RB40 reduced peroxide value and increased ferric reducing power of the packaged seasoning powder after 14 days. These results suggest that the presence of rice germ flour in the film was associated with the higher antioxidant capacity observed in the packaged seasoning powder. RB40 shows potential for use as a dissolvable edible film for instant food seasoning.