EFFECT OF CHEMICAL TREATMENTS OF SUGAR-BEET FIBER ON THEIR PHYSICOCHEMICAL PROPERTIES AND ON THEIR INVITRO FERMENTATION

Chemically treated and dried sugar beet fibres were fermented in vitro in order to study the effects of chemical and physico-chemical parame ters of dietary fibre on their colonic fermentation. Sugar beet fibre was treated with dilute alkali, removing mainly acetyl and methyl este r groups, and/or with dilute acids eliminating arabinose, galactose an d certain uronic acid residues. The chemical treatments led to an incr ease in the hydration properties and fermentability by improvement of the accessibility of the remaining polysaccharides. However, if the ch emically treated fibres were dried under harsh conditions (100-degrees -C), their hydration properties and their fermentability were limited, probably because of structural collapse of the fibre matrix. Whatever the conditions for chemical treatments and drying of the sugar beet f ibres, it was possible to predict their fermentability from the water- binding capacity. Because of the relationship between the physiologica l effects of dietary fibres and the extent to which they are fermented , this result underlines the importance of the physico-chemical charac terisation of the fibre in order to acquire a better knowledge of thei r physiological effects.