High (1→3,1→4)-β-glucan barley fractions in bread making and their effects on human glycemic response

Barley flour (BF) from whole naked grain and two (1-->3,1 -->4)-beta-glucan-enriched fractions, a sieved fraction (SF) and a water-extracted fraction (WF), were produced and mixed with bread wheat flour (BW, for bread-making quality evaluation. Bread was baked in a pilot plant and analysed for sensory properties, proximate composition and (1-->3,1-->4)-beta-glucan content. Four kinds of bread were produced from different mixtures of barley ingredients and bread wheat flour: a 100% BW ((1-->3,1-->4)-beta-glucan content: total, 0.1%; soluble, 0.1%); a 50% BW and 50% BF (2.4%; 2.0%); a 50% BW and 50% SF (4.2%; 2.8%); an 80% BW and 20% WF (6.3%; 5.7%). Eight adults were fed test meals of each of the four breads, containing the same amount (50 g) of available carbohydrate, and glycemic indices calculated from finger-prick capillary blood samples. A linear decrease in glycemic index was found for increasing (1-->3,1-->4)-beta-glucan content. The 20% WF bread had a 28% lower glycemic index than the plain BW and also showed the best scores for sensory attributes. This research confirms the effectiveness of viscous (1-->3,1-->4)- beta-glucan in reducing postprandial blood glucose levels, even in foods with a high glycemic index. The enrichment technique, and water extraction/freeze-drying technique, could enable the use of barley as a source of a high-value fibre for reducing the glycemic index of traditional wheat-based foods such as bread, without negatively affecting their sensory characteristics. (C) 2002 Elsevier Science Ltd.