Exo-type, endo-type and debranching amylolytic enzymes regulate breadmaking and storage qualities of gluten-free bread

Starch is crucial to gluten-free bread (GFB) quality. Amylolytic enzymes modified starch in situ during breadmaking , impacting the quality of both fresh and stored bread. Here, the breadmaking and storage properties of GFB with added endo-amylases, exo-amylases and debranching enzymes were compared. The results demonstrated that the addition of amylolytic enzymes, especially exo-amylases and debranching enzymes, facilitated interactions between the enzymatically modified starch segments and structural agents to improve the structure and texture of fresh GFB. Exo-type β-amylase produced lower crumb firming rate than endo-type α-amylase, although they produced similar retrogradation enthalpies and relative crystallinities . Maltooligosaccharide-forming enzymes with a non-strict endo-/exo-mode of cleavage and debranching enzymes markedly reduced the crumb firming rate and retrogradation enthalpy. Yet, maltooligosaccharide-forming enzymes produced a similar relative crystallinity as α-amylase, indicating that enzymes with endo-/exo-modes depended less on the reduction of starch recrystallization to retard crumb firming compared with debranching enzymes.