The potential use of (1→3, 1→4)-β-D-glucan from barley as a functional food ingredient for cereal foods
The health related importance of dietary fibre as part of a balanced diet is well known. More recently, soluble fibres, such as (1→3, 1→4)-β-D-glucan (β-glucan), have been shown to influence glycaemic, insulin and cholesterol responses to foods. Barley is a rich source of β-glucan; however, consumption of products containing barley grain or flour is often limited by their negative organoleptic quality. A potential solution lies in the use of barley as an extraction source for β-glucan fractions. One problem with regards to this is the lack of clarity on the use of barley β-glucan fractions in food systems, particularly their physiological and physico-chemical properties. The aim of this study was to determine the potential of barley β-glucan fractions as functional ingredients in cereal foods. The effects of extraction treatment on fraction composition and physico-chemical properties were investigated. Subsequently, barley β-glucan fractions (from a bench-top and commercial extraction procedure and of differing molecular weight) were incorporated into white wheat bread and durum wheat semolina pasta. The effects on product quality and in vitro starch digestibility were investigated. Simultaneously, the effect of processing on the degradation of β-glucan molecular weight was evaluated. Different extraction treatments may influence the composition and physico-chemical properties of barley β-glucan fractions. The inclusion of barley β-glucan fractions in bread and pasta resulted in a slight reduction of product quality but generally reduced the rate and extent of in vitro starch digestibility. Factors such as composition, water retention capacity, integration within the cereal food matrix and molecular weight may influence the behaviour of the fractions. Bread manufacture resulted in degradation of β-glucan molecular weight, although only high molecular weight β-glucans were susceptible to degradation. The results of the study have both scientific and commercial value and provide foundations for further development of barley β-glucan enriched cereal products.