Impact of replacing wheat flour with lychee juice by-products on bread quality characteristics and microstructure

Lychee juice by-product dietary fiber is a good source of dietary fiber, with a fine texture and easy acceptance by consumers. This study explored the effects of adding 5%–25% lychee pulp dietary fiber (LPDF) on bread quality characteristics and microstructure. The results showed that bread volume with 5%–15% LPDF was significantly higher than that of bread with 20% and 25% LPDF. A denser structure was formed in the bread after adding excessive LPDF, as observed by scanning electron microscopy images, with increased hardness and decreased bread elasticity. Adding LPDF enriched the cellulose I of dietary fiber and reduced the V-type amylose lipid complex, weakening the gluten network. Notably, the appropriate addition of LPDF gradually changed the starch particles into flake starch, which increased the gumminess and improved the chewiness of the bread. Our results indicate that bread samples with 15% specific-particle-size LPDF were rich in dietary fiber. Our results provide a scientific basis for the formulation of a healthy bread rich in lychee dietary fiber.