Effect of various thermal treatments on the pasting properties of enriched β-glucan oat products

Pasting properties of oat hydrocolloid-enriched products with 12% oat bran concentrate (OBC), 20% beta-glucan enriched hydrocolloid (BGE-OH20) or 30% (BGE-OH30) beta-glucan content were studied under different temperature conditions using a Rapid Visco Analyser (RVA) of 8% (w/w) oat suspensions in water. A typical starch RVA profile was compared with lower heating rates, lower maximum temperature, shorter holding times at maximum temperature, and slower cooling rates. No significant differences were observed in pasting proper-ties of the oat hydrocolloid products heated up to 95 degrees C at different rates using a typical starch RVA profile. OBC breakdown and setback viscosity were observed only at 95 degrees C. At 75 and 85 degrees C, BGE-OH30 had significantly higher final and setback viscosity. BGE-OM20 heated upto 95 degrees C at 2 degrees C/min had significantly higher peak and breakdown viscosity than at 4 degrees C/min. BGE-OH30 pastes had higher peak, trough, breakdown, final and setback viscosity than BGE-OH20 pastes held at 75 or 85 degrees C for 0-5.5 min. Significant differences between BGE-OH20 and BGE-OH30 were observed for final and setback viscosity of pastes cooled from 95 degrees C to 50 degrees C at 2 degrees C/min, 4 degrees C/min or 6 degrees C/min, with lower viscosity at 2 degrees C/min cooling rate. Differences observed in pasting properties could be attributed to P-glucan content or extent of P-glucan starch interactions. Based on our findings, we recommended studies of OBC pasting properties should use a typical starch RVA profile involving heating to 95 degrees C and P-glucan-enriched oat hydrocolloid products ( >= 20%) should use RVA profile with maximum temperature of 75 to 85 degrees C, has short holding time (2 min) and cooling rate of 6 degrees C/min.