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 cer eal samples prior to in vitro fermentation is presented. A statistical expe rimental 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 whil e wheat breads, were tested to evaluate the performance of the digestion pr ocedure. Pepsin and bile enhanced the hydrolysis of slowly digestible starc h. The extent of starch hydrolysis in rye and wheat breads (93-95%) was rep roducible and about the same as using thermostable alpha-amylase. More solu ble fibres were released from the wholemeal rye bread than from the wholeme al 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 c an also be used as a tool for studying the solubility of dietary fibre (DF) . (C) 1999 Academic Press.