Subcritical water hydrolysis of industrial cake leftovers for sugar production

Cakes are bakery goods that are frequently discarded. Cake leftovers are mostly carbs with a significant potential for sugar recovery using subcritical water hydrolysis; a clean, rapid, and sustainable approach. This study aimed to evaluate the highest sugar that could be recovered from cake leftovers using subcritical water hydrolysis. The cake leftovers were hydrolyzed in a batch-type subcritical water reactor at the process conditions of 160 degrees C - 200 degrees C, process time (5-15 minutes), and solid loading (10% - 50%). The yields of total sugar and reducing sugar rose parallelly to the process conditions. The optimal process parameters for sugar recovery of the cake leftovers were 200 degrees C, 15 minutes, and 50%, yielding a total sugar yield of 0.895 mg/ml and a reducing sugar yield of 0.700 mg/ml. Hydrolysis of the carbohydrates resulted in sucrose, glucose, fructose, galactose, xylose, and mannose. Results from the scanning electron microscope (SEM) demonstrated that at higher temperatures (200 degrees C), the surface of cake leftovers looked to be considerably changed. This study has set the framework for future research into the uses and benefits of subcritical water hydrolysis.

Automated summary

This study demonstrated the potential of subcritical water hydrolysis for sugar recovery from cake leftovers. The optimal process parameters were found to be 200 degrees C, 15 minutes, and 50% solid loading, yielding a total sugar yield of 0.895 mg/ml and a reducing sugar yield of 0.700 mg/ml. Carbohydrate hydrolysis resulted in the formation of sucrose, glucose, fructose, galactose, xylose, and mannose.