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 an in vitro enzymic batch method for pretreatment of cereal samples prior to in vitro fermentation 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 Tvas studied by measuring glucose released and total starch in the digestion residue of rye flour. Four samples, wholemeal rye flour and bread, wholemeal and while 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 thermostable alpha-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 Drier to in vitro fermentation. The method can also be used as a tool for studying the solubility of dietary fibre (DF). (C) 1999 Academic Press.