Food Chemistry

Carbohydrate (bio)chemistry

Description of theme

Carbohydrates determine to a large extent quality attributes of the final food product while polysaccharides (e.g. pectic substances, hemicelluloses, cellulose) as present in fresh fruits and vegetables (e.g. ripeness, texture) determines their typical characteristics as well as their processing characteristics in the manufacture of foods (juices, nectars, purees, preserves). Polysaccharides also influence the extractability of important constituents of plant raw materials like sugar, oil, proteins, etc. Extra-cellular polysaccharides (EPS’s) from Lactocuccus Lactus sp. have been studied intensively, due to their importance in yogurt type of products and their potential as new food ingredient. In addition, the production of "tailor made" oligosaccharides as ‘functional ingredient’ for food and feed applications is having our attention for several years.

In general, various classes of carbohydrates (e.g. polysaccharides) are (specifically) extracted from the starting material (waste materials like beet pulp, spent grain, cereal bran), fruits and vegetables or products derived herefrom (juices, canned fruits etc.) and characterised by chemical parameters (sugar composition, sugar linkage composition, substituents. Using various types of (preparative) chromatographic techniques, unknown oligo- and polysaccharides are isolated and characterised by NMR and mass-spectroscopic techniques). Also pure and well characterised enzymes are used to release (oligomeric) degradation products. The structure of these oligomers (HPAEC, MS, NMR), together with the mode of action of the enzymes used, will lead to a working model of the native carbohydrate with respect to e.g. type, amount and distribution of substituents and side chains over the polymeric backbone.

When possible, relationships between the chemical fine structure of the carbohydrate under investigation and the corresponding functional property of this carbohydrate (isolated or as present in the original product) will be established.

Typical raw materials (and product derived there from) under investigation are: cereals like wheat, sorghum, maize; apple, tomato, potato, soy beans, olives, sugar beet, etc.

Research Projects