The digestion mechanism of jackfruit seed starch using improved extrusion cooking technology

Abstract

To investigate the digestion mechanisms of EJFSS, the structural characteristics of slowly digestible starch (SDS) and resistant starch (RS) fractions isolated from native and extruded JFSS were studied. The SDS + RS and RS fractions in both native JFSS and that treated by IECT exhibited higher gelatinization temperatures, relative crystallinity and short-range molecular order, but lower gelatinization enthalpy (ΔH), than the control. Compared to the native JFSS, the ΔH, relative crystallinity and molecular order of JFSS subjected to IECT were significantly decreased (P < 0.05), indicating the double helix and long and short range order of JFSS were destroyed after IECT treatment. This was evidenced by the molecular structure of samples subjected to IECT treatment, which included a smaller molecular size of amylopectin and lower amylopectin content. The samples had an amylose peak but did not have a discernible amylopectin peak, indicating that amylopectin, which exhibited more extensive branching, was more susceptible to shear degradation than amylose. Compared to native SDS + RS and RS fractions, the SDS + RS and RS fractions treated by IECT exhibited a higher proportion of short amylopectin chains. Analysis of the microstructure further supported the above result in that, compared to native samples, a more loose and porous structure was observed in the extruded JFSS samples, which were easily attacked by enzymes. All results indicated that compared to native JFSS samples, amylopectin degradation by IECT treatment did not contribute to the formation of perfect crystals, which are more prone to hydrolysis.