Submitted to: Journal of Food Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 14, 2006
Publication Date: March 27, 2007
Citation: Stevenson, D.G., Inglett, G.E. 2007. Effect of various thermal treatments on the pasting properties of enriched beta-glucan oat products. Journal of Food Science and Technology. 44(2):168-173. Interpretive Summary: Pasting properties under different temperature test conditions using the Rapid Visco Analyser (RVA) were evaluated for oat bran concentrate (12% beta-glucan content), C-trim20 (20% beta-glucan content), and C-trim30 (30% beta-glucan content) to find if there were more appropriate test conditions for beta-glucan-enriched oat products than the presently used test conditions based on starch samples. Oat bran concentrate did not exhibit normal pasting curves if the temperature was below 95 deg C. Improved sensitivity in viscosity measurements was observed for the C-trim beta-glucan enriched products if temperature was lowered, and holding time at maximum temperature was shortened. These basic studies will assist food processors in incorporating c-trim oat products into food that imparts a desirable texture for consumers.
Technical Abstract: Oat hydrocolloid-enriched products with 12% (oat bran concentrate (OBC)), 20% (C-trim20), or 30% (C-trim30) beta-glucan content had pasting properties 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 properties of the oat hydrocolloid products heated at different rates up to 95 deg C using a typical starch RVA profile, and high variability was observed. OBC breakdown and setback viscosity was only observed at 95 deg C. At 75 deg C and 85 deg C, C-trim30 had significantly higher final and setback viscosity. C-trim20 heated up to 95 deg C at 2 deg C/min had significantly higher peak and breakdown viscosity than 4 deg C/min. C-trim30 pastes had higher peak, trough, breakdown, final, and setback viscosity than C-trim20 pastes held at 75 deg C or 85 deg C for 0-5.5 min. Significant differences between C-trim20 and C-trim30 were observed for final and setback viscosity of pastes cooled from 95 deg C to 50 deg C at 2 deg C/min, 4 deg C/min, or 6 deg C/min with lower viscosity at 2 deg C/min cooling rate. Differences observed in pasting properties could be attributed to beta-glucan content or extent of beta-glucan-starch interactions. Based on our findings, we recommend that studies of OBC pasting properties should use a typical starch RVA profile involving heating to 95 deg C. Beta-glucan-enriched oat hydrocolloid products (greater than or equal to 20%) should use an RVA profile that heats to 75 deg C or 85 deg C, because it has a short holding time (2 min) and cooling rate of 6 deg C/min.