Oat Gum and β-Glucan Extraction from Oat Bran and Rolled Oats: Temperature and pH Effects

The extractability of oat gum from oat bran and rolled oats was studied using 12 treatment combinations in a factorial design (2x3x4x2) i.e. 2 oat products; 3 pH (8.0–10.5); 4 temperatures (5O–70°C); 2 replications. The extraction procedure involved: (a) alkaline treatment of flour and removal of starch residue; (b) isoelectric precipitation of protein residue [namely, protein concentrates (PC)]; (c) and alcohol precipitation of oat gum/β-glucan and collection of gum by centrifu-gation. Extracted oat gum ranged from 2.99–6.28% for oat bran and 1.82–5.24% for rollcd oats whereas β-glucan (in gum) ranged from 70–89% and 50–68%, respectively. Protein contents of the PC from oat bran was 69–91% and rolled oats 66–89%. Correspondingly, starch content of residues ranged from 30–63% and 61–47%. Oat gum/β-glucan extracted at pH 9.2/50°C or pH 10.5/50/55°C showed little or no starch contamination.