Extraction And Biodegradation Of Xylan From Paddy Hull

Xylo-oligosaccharide, the product of biodegradation of hemi cellulose, is the high additional value substance. Nowadays, there is a research upsurge of the functional food in the world. The functional ligosaccharides have been a kind of important functional food additive because they have special physiological function. Xylo-oligosaccharide is one of the functional ligosaccharides. The biodegradation of xylan to prepare xylo-oligosaccharide is still the main method at present.This paper mainly studied xylan extraction from paddy hull, aspergillus niger mutation by ultraviolet ray, xylanase characteristic and the condition of xylan biodegradation.The content of xylan from paddy hull was 19.9%. The variables which affect extraction: alkaline (NaOH) concentration, the ratio of solid to liquid, extraction temperature and extraction time. The better extractive conditions was obtained : alkaline concentration was 10%, the ration of solid to liquid 1:10, extraction time was 3h ,temperature was 60-95 C .The yield of xylan from paddy hull was 67.50%.A high aspergillus niger strain was obtained by using ultraviolet ray. Mutation effect is best when lethal was 85% or so. The best mutation conditions of aspergillus niger were as follows: UV watt was 40, irradiant distance was 28cm, irradiant time was 2.5min. Xylanase activities produced by mutation aspergilus niger were determined. The optimum reaction temperature was 50C, the optimum reaction pH was 4.2. The xylanase stability to temperature and pH was studied too.The influencing factors of xylan biodegradation include substrate concentration, enzyme dosage, enzyme time, enzyme temperature and enzyme pH etc. The substrate concentration and enzyme dosage to xylan degradation were studied espectially.It determined enzyme activity and sugar content through DNS method. That was available composition was analyzed with UV at 480nm.This paper offered a new method for advancing paddy hull's use. It could dispose agriculture and forestry offal and solve the problem of environmental pollution. It had good economic and social benefit.