The Combined Effects Of Extrusion And Recrystallization Treatments On The Structural And Physicochemical Properties And Digestibility Of Corn And Potato Starch

This study aimed to compare the effects of extrusion and recrystallization treatments on the structural and physicochemical properties and digestibility of corn (CS) and potato starch (PS). CS and PS were conditioned at 40 % and 60 % moisture content and extruded at 40 degrees C-120 degrees C. The extrudates were stored for 1, 7, and 14 days at 4 degrees C for recrystallization. The structural properties of extruded CS (ECS) and extruded PS (EPS), as well as the crystallization and thermal properties, water solubility, water absorption, and in vitro digestibility of recrystallized ECS (RECS) and recrystallized EPS (REPS), were evaluated. Compared with native starch, both ECS and EPS exhibited a significant decrease in their measured molecular weight. The chain length distribution did not change significantly, but the amylose content increased remarkably. Both RECS and REPS with 60 % moisture content presented a typical B-type pattern, and RECS exhibited V-type characteristic peaks. The melting signals of recrystallized amylopectin (46-64 degrees C) and amylose (136-158 degrees C) of RECS were detected. In vitro digestion experiments showed that RECS had lower digestibility than REPS. The highest slowly digestible starch and resistant starch contents of RECS were approximately 3.5 and 6.5 times that of unextruded CS, respectively.