Production of modified xylans and xylooligosaccharides for valorization of rice straw
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Date
2020
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Punjab Agricultural University, Ludhiana
Abstract
The present study attempts to valorise rice straw, one of the most abundant,
renewable, economic and environment-friendly agricultural wastes, by the production of
modified xylans and xylooligosaccharides (XOS). The chemical composition of rice straw
was determined using detergent system method and the percent contents of extractives,
cellulose, hemicellulose, lignin and ash (silica) were found to be 20, 41, 24, 9 and 6,
respectively. Alkaline extraction procedure employed for extracting hemicellulose was
optimized using central composite design of response surface methodology such that
maximum yield of hemicellulosic xylan (19.97%) was obtained by carrying out reaction with
11.04% (w/v) NaOH for 3.126 hrs at 80.146 . Hemicellulosic xylan was structurally
characterized by FT-IR and NMR spectroscopic studies and subjected to chemical
modifications i.e. acetylation, benzylation and carboxymethylation followed by their spectral
analysis. Total antioxidant capacity of xylan and modified xylans was evaluated by
phosphomolybdenum method using ascorbic acid as standard. Although the ascorbic acid
equivalent (AAE) value of xylan was higher than modified products but higher thermal
stability of modified xylans may account for their suitability in formation of packaging films.
Autohydrolysis of xylan was carried out with dilute sulphuric acid (0.1, 0.25, 0.5 and 1.0M) at
121oC, 15 psi for 10 min to obtain XOS-rich autohydrolysates which were qualitatively
analysed using thin layer chromatography. These autohydrolysates were found to exhibit
significant concentration dependent antioxidant activity and higher prebiotic potential for
growth of Lactobacillus rhamnosus and Lactobacillus casei than established prebiotic
fructooligosaccharides.
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Puneet Kaur (2020). Production of modified xylans and xylooligosaccharides for valorization of rice straw (Unpublished M.Sc. thesis). Punjab Agricultural University, Ludhiana, Punjab, India.