2022

Rosa-Sibakov, Natalia; Sorsamäki, Lotta; Immonen, Mikko; Nihtilä, Hanna; Maina, Ndegwa H.; Siika-aho, Matti; Katina, Kati; Nordlund, Emilia

Food-grade enzymes (α-amylase, amyloglucosidase, maltogenic amylase and protease) were investigated for recycling waste bread back to wheat bread-making process. Waste bread was efficiently hydrolysed into sugars (up to 93% glucose yield) and the best combination of enzymes was α-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 (i) hydrolysed slurry, i.e. hydrolysed waste bread without solid/liquid separation and (ii) syrup, i.e. liquid supernatant after centrifugation of the hydrolysed waste bread. Both hydrolysed bread slurry and syrup were successfully utilized to replace sucrose (2 and 4%) during 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.