Digestion of barley malt porridges in a gastrointestinal model: Iron dialysability, iron uptake by Caco-2 cells and degradation of beta-glucan

Iron availability and degradation of (1 -> 3,1 -> 4)-beta-D-glucan (beta-glucan) in three whole grain porridges made from two optimised barley malts and unprocessed barley were studied in a dynamic gastrointestinal model. The malting processes, with steeping at 15 or 48 C with lactic acid (LA), enabled a complete reduction of phytate by subsequent soaking of ground malt, still with well preserved beta-glucan. Iron dialysability and iron uptake by Caco-2 cells were higher in phytate reduced porridges, compared to the reference porridge. During simulated digestion, the extractability of beta-glucan increased and the Calcofluor average molecular weight decreased for all porridges, indicating a gradual degradation during passage through the model. The degradation rate, however, appeared lower in porridge prepared from malted barley steeped at 48 degrees C with LA. The gastrointestinal model ranked iron availability according to human absorption data and showed high repeatability when evaluating changes in beta-glucan. The results indicate the potential for using high temperature steeping with LA to yield improved iron availability combined with reduced degradation of beta-glucan in the small intestine, maintaining the beneficial properties of barley. (c) 2005 Elsevier Ltd. All rights reserved.