Development, characterisation and biodegradability of rice straw lignin based sustainable biopolymeric films

• Published in: International journal of food science & technology Vol. 58; no. 5; pp. 2754 - 2763
• Main Authors: Dudeja, Isha, Mankoo, Ramandeep Kaur, Singh, Arashdeep, Kaur, Jupinder
• Format: Journal Article
• Language: English
• Published: Oxford Wiley Subscription Services, Inc 01-05-2023
• Subjects: Antioxidants; Biodegradability; Biodegradation; Bioplastics; Biopolymeric film; Body weight loss; characterisation; Citric acid; Crosslinking; Diameters; Electron micrographs; Elongation; Food contamination; Food packaging; Fourier transforms; Infrared radiation; Lignin; mechanical properties; Pollution prevention; Rice straw; Soil contamination; Straw; Tensile strength; Thickness; Weight loss
• ISSN: 0950-5423; 1365-2621
• DOI: 10.1111/ijfs.16105

Summary
The present study involved valorization of rice straw via production of biopolymeric films loaded with lignin and evaluation of their physical, mechanical, structural, antioxidant, antibacterial and biodegradable properties. Lignin (0.1%, 0.2% and 0.3%) loaded films were prepared by solvent casting method involving successful crosslinking between PVA, citric acid and lignin which was confirmed by ester bond formation at 1710 cm−1 in Fourier transform infrared spectrum. Scanning electron micrographs showed smooth surface in control and wavy surface in lignin film with no cracks. Lignin films possessed thickness, tensile strength and elongation at break in the range 0.127–0.142 mm, 22–31.38 MPa and 11.83–17.63%, respectively. Lightness value of films decreased while yellowness index increased as the level of lignin increased in films. Lignin loaded films showed potential antioxidant activity (51.4–74.6%) and antibacterial efficacy against Pseudomonas (diameter of inhibition zone 4.1 cm), thus suggesting their role in prevention of bacterial food contamination and organoleptic changes in food. The biodegradability tests showed that weight loss experienced by films after burial in soil was above 78.7% which offers a great advantage of these biopolymeric films over non‐biodegradable synthetic plastics, hence, these may be explored further as bioplastics to replace plastic wraps in food packaging.
Lignin was efficiently extracted from rice straw. Biopolymeric films were synthesized by crosslinking lignin with PVA using citric acid as crosslinker and glycerol as plasticizer. The films were characterized using FT‐IR and FE‐SEM studies. Biopolymeric films possessed good mechanical, antioxidant, antibacterial and biodegradability potential. Lignin based biopolymeric films can be explored as food packaging wraps to replace synthetic plastics.