Fortification of Wheat Bread with Increasing Levels of Kudzu (Pueraria lobata) Root Powder: Technological, Nutritional, and Sensory Implications

The growing interest in functional bakery products has driven research toward the incorporation of non-conventional plant materials rich in dietary fiber. In this study, the effects of partial substitution of wheat flour with ground kudzu root (Pueraria lobata) at levels of 3%, 6%, 9%, and 12% on dough rheology and bread quality were investigated. Farinograph analysis showed that kudzu addition slightly increased water absorption and dough development time, while significantly improving dough stability and the farinograph quality number. At the same time, a higher degree of dough softening indicated partial weakening of the gluten network at higher substitution levels. The incorporation of kudzu root significantly increased bread yield due to enhanced water retention associated with its high dietary fiber content. However, a reduction in specific volume was observed at the highest substitution level (12%), indicating limitations in gas retention capacity. Crumb structure analysis revealed a shift toward a finer and more homogeneous pore distribution with increasing kudzu content, accompanied by a reduction in large pores. These structural changes were reflected in texture profile analysis, where increased hardness and chewiness were observed, particularly at higher substitution levels, while cohesiveness and springiness were only slightly affected. Partial substitution with kudzu root powder also resulted in a significant increase in total phenolic content, flavonoid content, and antioxidant potential of the breads, with the highest values observed in samples containing 12% kudzu root powder. In addition, breads enriched with kudzu root showed reduced digestible starch content compared with the control sample. Despite these modifications, breads enriched with up to 9% kudzu root maintained acceptable technological quality, balancing improved water retention with moderate changes in structure and texture. The results demonstrate that kudzu root can be used as a functional ingredient in wheat bread, contributing to increased dietary fiber content while maintaining satisfactory processing and quality characteristics.