Functionality and economic feasibility of enzymatically hydrolyzed waste bread as a sugar replacer in wheat bread making

Food-grade enzymes (alpha-amylase, amyloglucosidase, maltogenic amylase, and protease) were investigated for recycling waste bread back to wheat bread-making process. Waste bread was efficiently hydrolyzed into sugars (up to 93% glucose yield) and the best combination of enzymes was alpha-amylase (0.05 g/kg bread) and amyloglucosidase (2.5 g/kg bread). Selected enzyme hydrolysis processes were tested in wheat bread making as a (a) hydrolyzed slurry, that is hydrolyzed waste bread without solid/liquid separation and (b) syrup, that is liquid supernatant after centrifugation of the hydrolyzed waste bread. Both hydrolyzed bread slurry and syrup were successfully utilized to replace sucrose (2 and 4%) in bread making without affecting the bread quality when compared to the control bread. Techno-economic assessment revealed that this approach is 12% more economical than the current mean to dispose the bakery waste. This recycling concept showed both technical and economic potential for bakery industries to overcome their excess bread production. Novelty impact statement A new recycling process was developed by using enzymes to efficiently hydrolyze surplus bread into sugars. The use of those sugar-rich slurries and syrups in bread rework did not affect the bread quality when compared to the control bread. The recycling concept was more economical than current means to dispose waste bread, revealing the technical and economic potential for bakery industries to overcome their excess bread production.