Improvement of the quality and shelf life of wheat bread by a maltohexaose producing α-amylase

Starch modification by amylolytic enzymes has been proved feasible in restraining aging behavior during the starchy food storage. The objective of this study was to determine the contribution of a maltohexaose (G6) producing α-amylase AmyM to the anti-staling properties of bread. Hydrolyzed wheat starch with different degree of hydrolysis (DH) was related to anti-retrogradation from the differential scanning calorimetry (DSC) analysis, and complete inhibition of retrogradation when starches were hydrolyzed to >25.5% DH with increased malto-oligosaccharides (Mw < 5 kDa). Rheological measurements showed that the use of small enzyme fraction (0.02 mg/kg) was enough to enhance the viscous characteristics of whole bread dough with increased tan δ and decreased G'. During 12 days storage of the prepared bread, there was a clear increase in hardness and chewiness from the control sample, while the bread from AmyM treatment exhibited slow trend with 733 and 602 at day 12, respectively. The extend shelf life and improved quality from AmyM treatment (0.02 mg/kg) were comparable to the commercial amylase with recommended usage (5 mg/kg). These results indicate that AmyM could be considered as an alternative anti-staling agent in the baking industry.