Xylan

Xylan ( ; ) (CAS number: 9014-63-5) is a type of hemicellulose, a polysaccharide consisting mainly of xylose residues. It is found in plants, in the secondary cell walls of dicots and all cell walls of grasses. Xylan is considered to be the second most abundant plant biopolymer, and the third most abundant polysaccharide on Earth after cellulose and chitin.

Xylan ( ; ) (CAS number: 9014-63-5) is a type of hemicellulose, a polysaccharide consisting mainly of xylose residues. It is found in plants, in the secondary cell walls of dicots and all cell walls of grasses. Xylan is considered to be the second most abundant plant biopolymer, and the third most abundant polysaccharide on Earth after cellulose and chitin. ===Algae=== Some macrophytic green algae contain xylan (specifically homoxylan ) especially those within the Codium and Bryopsis genera where it replaces cellulose in the cell wall matrix. Similarly, it replaces the inner fibrillar cell-wall layer of cellulose in some red algae. ===Food science=== The quality of cereal flours and the hardness of dough are affected by their xylan content, thus, playing a significant role in bread industry. The main constituent of xylan can be converted into xylitol (a xylose derivative), which is used as a natural food sweetener, which helps to reduce dental cavities and acts as a sugar substitute for diabetic patients. Poultry feed has a high percentage of xylan. Xylan is one of the foremost anti-nutritional factors in common use feedstuff raw materials. Xylooligosaccharides produced from xylan are considered as "functional food" or dietary fibers due their potential prebiotic properties. ==Breakdown== Xylanase converts xylan into xylose. Given that plants contain up to 30% xylan, xylanase is important to the nutrient cycle. The degradation of xylan and other hemicelluloses is relevant to the production of biofuels. Being less crystalline and more highly branched, these hemicelluloses are particularly susceptible to hydrolysis. ==Research== As a major component of plants, xylan is potentially a significant source of renewable energy especially for second generation biofuels. However, xylose (backbone of xylan) is a pentose sugar that is hard to ferment during biofuel conversion because microorganisms like yeast cannot ferment pentose naturally. ==References==

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