Development of an in vitro enzymic digestion method for removal of starch and protein and assessment of its performance using rye and wheat breads

The development of anin vitroenzymic batch method for pretreatment of cereal samples prior toin vitrofermentation is presented. A statistical experimental design is described and the importance of bile and pepsin for the digestibility of starch was investigated. Day-to-day variation was studied by measuring glucose released and total starch in the digestion residue of rye flour. Four samples, wholemeal rye flour and bread, wholemeal and white wheat breads, were tested to evaluate the performance of the digestion procedure. Pepsin and bile enhanced the hydrolysis of slowly digestible starch. The extent of starch hydrolysis in rye and wheat breads (93–95%) was reproducible and about the same as using thermostablealpha-amylase. More soluble fibres were released from the wholemeal rye bread than from the wholemeal wheat bread. The procedure is an efficient method for the removal of starch and protein under physiological conditions prior toin vitrofermentation. The method can also be used as a tool for studying the solubility of dietary fibre (DF)