Abstract

Barley is a valuable cereal with an old tradition in malt, food and feed. With new food applications this cereal can be rediscovered. Addition of a malting step in a food process can change the texture and taste of a product. It is also a process with high potential for improvement of nutrient availability. Extractable cell-wall polysaccharides have been linked to some positive health effects in humans. In cereals, these polysaccharides are mainly beta-glucan and arabinoxylan. The structure of extractable arabinoxylan and the content of bound ferulic acid dimers were studied in different cereals. For determination of amount and molecular weight of beta-glucan a high performance size-exclusion chromatography system (HPSEC) was set up with detection based on the specific binding of Calcofluor to β-glucan. This system was calibrated using a purified β-glucan fractionated into known narrow molecular weight ranges. A naked and a covered barley steeped and germinated at different temperatures and with different additions in the steeping water were studied. The total content and the average molecular weight of beta-glucan in the treated samples showed small changes after steeping at high temperature (48 °C), while steeping at lower temperature (15 °C) gave a significantly lower content. This was correlated with a strong increase of beta-glucanase activity over the time of germination. Addition of lactic acid to the steeping water at 48 °C decreased the beta-glucanase activity. Porridges made from two malts with a low phytate content and intact beta-glucan were introduced into a dynamic gastrointestinal model. Yield of beta-glucan was found to increase with time spent in the model, while average molecular weight of beta-glucan decreased.