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Effect of Cooking and Storage on the Amount and Molecular Weight of (1→3)(1→4)-β-D-Glucan Extracted from Oat Products by an In Vitro Digestion System¹

¹Contribution 2423 of the Centre for Food and Animal Research, Agriculture and Agri-Food Canada, Ottawa. ²Centre for Food and Animal Research, Agriculture and Agri-Food Canada, Ottawa, Ontario, K1A 0C6, Canada. ³Corresponding author. E-mail: WoodP@EM.AGR.CA

The extractability and molecular weight of β-glucan in oat bran, oat bran muffins, and oat porridge and the changes taking place during processing and storage were studied. The β-glucan was extracted using hot water and a thermostable α-amylase and by an in vitro system that simulated human digestion. Molecular weight (MW) of the extracted β-glucan was determined using high-performance size-exclusion chromatography. Hot-water treatment extracted 50–70% of total β-glucan in oat bran samples and rolled oats. The chromatographic peak MW of extracted β-glucan was in the 1.4–1.8 × 10⁶ range. Using the in vitro digestion system, 12–33% of total β-glucan in bran and rolled oats was solubilized, and peak MW was in the same range as β-glucan extracted by hot-water treatment. In muffins, 30–85% of total β-glucan was solubilized by in vitro digestion, with a major difference in extractability among muffins from different recipes. Peak MW of extracted β-glucan was lower in all muffins when compared to original bran. During frozen storage, extractable β-glucan decreased by >50% in all muffins, but no change in peak MW of extracted β-glucan was detected.