Optimization of Fermentable Sugars Production from Stale Bread using Response Surface Methodology

Background: Bread is the major waste product worldwide. It contains a considerable amount of starch, which is easily converted into sugars using enzymes. The aim of this study was to produce fermentable sugars from stale bread using barley malt as substitute of commercial enzymes. Methods: Response surface methodology based on Box-Behnken design was applied to optimize the parameters of enzymatic hydrolysis such as malt content (1.25, 2.5 and 3.75%), hydrolysis temperature (55, 62.5 and 70°C) and hydrolysis time (1, 1.5 and 2 h) to maximize fermentable sugars yield. Result: This study showed that malt content and hydrolysis temperature had a significant effect on fermentable sugars yield that increased with the increase in these two parameters. In contrast, hydrolysis time had no significant effect on fermentable sugars yield. The optimal parameters were 2.75% for malt content, 64.41°C for hydrolysis temperature and 1.31 h for hydrolysis time. At these optimal conditions, the fermentable sugars yield was at maximum reaching 63.21%. The results of this study suggested that barley malt could potentially be used to substitute commercial enzymes.