This study investigated the production of bakery and sweet paste products containing the prebiotic fructooligosaccharide (FOS) using an in situ method with invertase. The FOS formation method was optimized for each product to ensure high quality and appropriate sweetness. The method effectively decreased the sugar content in the final product by 12.7-68.4% while maintaining quality. The FOS content was 3.8-4.8% in castella, 0.6-3.6% in sweet dough bread, and 7.5-8.5% in sweet chickpea paste. By contrast, the commercial method of adding FOS decreased product quality; castella product height decreased by 20.8%, and hardness increased by 79%. The specific volume of the sweet dough bread decreased by 17.4% and hardness increased by 59%. Therefore, we developed a commercially feasible method to efficiently utilize FOS in sugar-containing foods while maintaining their quality.
