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Effect of processing on physicochemical properties and efficacy of oat and barley beta-glucan
N. AMES (1), S. Tosh (2). (1) Agriculture & Agri-Food Canada, Winnipeg, MB, Canada; (2) Agriculture & Agri-Food Canada, Guelph, ON, Canada

Barley and oat, major cereal grains grown in Canada, are rich sources of beta-glucan (BG) and total dietary fibre, making them valuable ingredients for functional foods. BG from oat and barley is known for its cholesterol lowering benefits, which have been recognised by health claims throughout the world, and its role in improving glycemic response has been documented in numerous scientific papers. Characteristics of BG believed to be important for incurring these benefits include viscosity, which is determined by concentration, solubility and molecular weight (MW). Therefore external factors (e.g. genotype, growing location and processing) that effect a change in one or more of these BG properties have the potential to influence physiological efficacy. In this study a wide range of techniques used in commercial and laboratory scale processing of oat and barley were examined for their effect on viscosity, solubility and MW. Processing methods included oat milling and flaking, other hydrothermal grain treatments, food processing techniques such as extrusion and tortilla production, as well as modifications to food preparation protocol. In most cases viscosity was increased through moderate processing treatments. Based on the results obtained, we were able to create barley food products with specific BG viscosity and MW properties (3 and 5 g BG dose with low viscosity/MW; 3 g BG dose with high viscosity/MW), which were used in a clinical trial to test cholesterol lowering effects in humans. The initial results revealed that all three BG diets used in the study significantly improved the total cholesterol levels in human. More importantly, high MW BG was more effective in reducing circulating cholesterol levels. We also found that barley BG supplementation was effective in reducing blood pressure levels in a concentration dependent manner.

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