Delayed effect of superfine particle size of oat bran on starch retrogradation and hydrolysis of gluten-free rice bread during short-term storage

Abstract

Oat bran addition to rice bread results in quality deterioration especially during storage, but its superfine particle size probably relieves this side effect. This study focuses on the gluten-free and rice starch-based bread. The effects of different particle sizes at medium (MOB, 359.67 μm), fine (FOB, 153.67 μm) and superfine (SOB, 35.77 μm) on the short-term storage quality of rice bread was confirmed. Oat bran addition affected pasting properties of rice flour, leading to a significant decrease in values of final viscosity and setback, which was intensified much more by the smaller particle sizes. The decrease in particle size of oat bran also led to an increase in brightness and whiteness values of rice bread. Gas-holding capacity of rice bread was reduced by MOB and FOB, including specific volume, gas cell diameter and volume, but SOB reversed this reduction and recovered to the same level as control bread. SOB mitigated the increase in bread firmness during storage and led to the highest springiness while the lowest baking loss. The water-binding capacity of rice bread with SOB was much higher than that with MOB and FOB, according to the moisture migration analysis. The inhibition of water evaporation by SOB during storage further delayed the amylopectin retrogradation and starch recrystallization. Additionally, SOB prevented the rice starch hydrolysis, exhibited an increase in RS (35.39 %), which was much higher than those of MOB (23.30 %) and FOB (25.30 %). These findings supported the efficient inhibition of SOB on rice bread staling.