Impact of exogenous α-amylases on sugar formation in straight dough wheat bread

Abstract

The use of bacterial or fungal α-amylases is common in wheat bread production to improve several quality-related parameters such as loaf volume, crust color or staling behavior. To study the impact of exogenous α-amylases on straight dough wheat bread, we quantitated mono-, di- and oligosaccharides and residual α-amylase activity in bread crumb during storage for up to 96 h. Discovery-driven proteomics of the five α-amylase preparations studied showed that only a few different amylases per preparation were responsible for the hydrolytic effect. Compared to the control, the supplementation with α-amylase from Bacillus amyloliquefaciens in wheat dough preparation led to major changes in the sugar composition of bread crumb during storage with the formation of oligosaccharides like maltopentaose, maltohexaose, maltoheptaose, and maltooctaose. A residual activity corresponding to 4.0% of the applied activity was determined in the breads prepared with α-amylase from B. amyloliquefaciens, but no residual activity was detected for any of the other fungal or bacterial α-amylases from Aspergillus oryzae or Thermoactinomyces vulgaris. Whether the detected residual activity is related to the characteristics of bread staling or bread crumb properties must be clarified in further studies.

Impact of exogenous maltogenic α-amylase and maltotetraogenic amylase on sugar release in wheat bread

“…The endogenous activity of the wheat flour used for the baking experiments was 4.1 nkat/g dm (± 0.7) for α-amylase and 378.4 nkat/g dm (± 6.1) for β-amylase. As we have shown before, no cereal amylase activity was detected in the crumb of the control breads after baking [21].…”

“…The composition of mono-, di-, and oligosaccharides in bread crumb without addition of exogenous amylases (control) was already reported by Rebholz et al [21]. The contents were as follows, sorted in descending order: maltose: 14.6 mg/g dm (± 1.1), sucrose: 5.8 mg/g dm (± 0.8), glucose: 2.9 mg/g dm (± 0.6), fructose: 2.8 mg/g dm (± 2.0), maltotriose: 1.5 mg/g dm (± 0.1) and maltotetraose: 1.1 mg/g dm (± 0.3).…”

“…The extract was centrifuged (20 min; 20 °C; 3750×g) and the supernatant was collected for further analysis. To optimize the conditions for the tryptic digest of extracts, the protein contents were quantified via a RP-HPLC method with UV detection at 210 nm as described earlier [21].…”

Influence of Amylase Addition on Bread Quality and Bread Staling

“…Maltogenic amylase acts as an exoacting amylase, which catalyzes the hydrolysis of 1,4-glycosidic linkages in amylose, amylopectin, and related glucose polymers. 18 As stated by Rebholz et al, 19 the degradation of amylopectin side chains hinders starch recrystallization, resulting in a reduction in the starch firming rate. Additionally, the maltose produced by the addition of maltogenic amylase in bread may also contribute to the antistaling effects.…”

“…Maltogenic amylase acts as an exoacting amylase, which catalyzes the hydrolysis of 1,4-glycosidic linkages in amylose, amylopectin, and related glucose polymers . As stated by Rebholz et al, the degradation of amylopectin side chains hinders starch recrystallization, resulting in a reduction in the starch firming rate. Additionally, the maltose produced by the addition of maltogenic amylase in bread may also contribute to the antistaling effects. , A more recent study conducted by Bae et al showed that G4 amylase demonstrated positive impacts on improving the baking performance of whole-grain wheat bread, increasing bread volume and reducing bread staling.…”