Ramandeep KaurPuneet Kaur2021-09-102021-09-102020Puneet Kaur (2020). Production of modified xylans and xylooligosaccharides for valorization of rice straw (Unpublished M.Sc. thesis). Punjab Agricultural University, Ludhiana, Punjab, India.https://krishikosh.egranth.ac.in/handle/1/5810175608The 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.EnglishThesis