Pentosans

Pentosans are polysaccharides composed predominantly of five-carbon sugars, mainly xylose and arabinose. They belong to the group of plant hemicelluloses and are widespread in plant cell walls, with cereals showing especially high contents. In cereals, arabinoxylans are the principal pentosans, consisting of a xylan backbone with arabinose side chains; in other plants, related xylans or glucuronoxylans are common.

Structure and properties: Pentosans exhibit varying solubility. Some are water-extractable, contributing to viscosity in foods and beverages, while the insoluble fraction helps bind water in dough and plant tissues. Their rheological behavior influences processing properties such as dough handling, water absorption, and gel formation. Enzymatic or thermal treatment can modify pentosan integrity and thus the texture of products.

Occurrence and nutrition: Pentosans are a significant source of dietary fiber in human nutrition. They can be fermentable by gut microbiota, generating short-chain fatty acids, and may affect mineral nutrition and gut health. Their fiber-forming capacity also contributes to satiety and carbohydrate quality in cereals and cereal-based foods.

Measurement and significance: In plant materials, pentosans are commonly expressed as a percentage of dry matter. They are often separated into water-extractable and non-extractable fractions to reflect their impact on processing characteristics, such as dough rheology in baking and viscosity in brewing or pulping processes.