Investigating the impact of α-amylase, α-glucosidase and glucoamylase action on yeast-mediated bread dough fermentation and bread sugar levels

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Wheat flour is generally supplemented with α-amylases to increase maltose levels in bread dough and increase loaf volume. While the preference of yeast for glucose and fructose over maltose as substrate for fermentation is well documented, the impact of maltose versus glucose producing enzymes on bread dough fermentation kinetics and bread sugar levels is ill documented. Hence the impact of α-amylase, α-glucosidase and glucoamylase action on both aspects was investigated. Glucoamylase and α-amylase increase the total fermentable sugar content of dough, while α-glucosidase only affects the glucose/maltose ratio. Due to their effect on total fermentable sugar levels, addition of α-amylase or glucoamylase prolongs the total productive fermentation time, while this is not the case for α-glucosidase. In contrast to α-amylase, both glucoamylase and α-glucosidase supplementation leads to higher CO2 production rates during the initial stages of fermentation. In the final bread product, different sugar levels are observed depending on the dosage and type of starch-degrading enzyme. The results of this study imply that long and short fermentation processes benefit from α-amylase and α-glucosidase addition, respectively, while glucoamylase supplementation is suitable for both long and short fermentation times.