Structural, antioxidant, antibacterial and biodegradation properties of rice straw xylan (native and modified) based biofilms

• Published in: International journal of food science & technology Vol. 58; no. 5; pp. 2772 - 2781
• Main Authors: Kapil, Sristhi, Mankoo, Ramandeep Kaur, Dudeja, Isha, Singh, Arashdeep, Kaur, Jupinder
• Format: Journal Article
• Language: English
• Published: Oxford Wiley Subscription Services, Inc 01-05-2023
• Subjects: Absorption spectra; Acetylated xylan; antibacterial; antioxidant; Biodegradation; Biofilms; carboxymethylated xylan; Citric acid; Food packaging; Glycerol; Infrared spectroscopy; Polymers; Polyvinyl alcohol; Rice straw; Sodium hydroxide; Straw; Xylan
• ISSN: 0950-5423; 1365-2621
• DOI: 10.1111/ijfs.16118

Summary
The present study involved valorisation of rice straw by conversion of its constituent polymer xylan and chemically modified xylans into biofilms. Hemicellulosic xylan (19.94%) extracted with 10% NaOH (85 °C, 2.6 h) was chemically modified to acetylated (AX) and carboxymethylated xylan (CMX). Biofilms were prepared by reaction of xylan/modified xylan (1% and 2%) with polyvinyl alcohol using eco‐friendly and cheap cross‐linker citric acid and glycerol as plasticiser. 2% xylan biofilms showed maximum inhibition (94.25%) of DPPH at 4 mg mL−1 which was due to large number of free ‐OH groups (highest intensity of ‐OH absorption bands in FT‐IR spectra). 2% CMX biofilms exhibited maximum antibacterial effectiveness with diameter of zone of inhibition 33.5 and 30.5 mm against Bacillus subtilis and Pseudomonas sp., respectively. This may be due to large number of undissociated COO− ions (citric acid) in CMX biofilms which was evident from lesser cross‐linking observed in their SEM images. 2% CMX biofilms also showed the highest biodegradation (86.5%) which may be attributed to formation of ether bonds along with ester bonds leading to their fast degradation. Owing to good bioactive properties of prepared biofilms, it was concluded that these can be appropriate material for food packaging by replacing synthetic plastics.
Xylan was efficiently extracted from rice straw. Xylan was chemically modified into acetylated and carboxymethylated xylans. Biofilms were prepared by cross‐linking xylans (native and modified) with PVA in the presence of citric acid and glycerol. Prepared biofilms were characterised using FT‐IR and SEM studies. Xylan‐based biofilms were observed to possess good antioxidant, antibacterial and biodegradability potential. These biofilms can be explored as bioplastics for potential applications in food industry.