Extrusion induced low-order starch matrices: Enzymic hydrolysis and structure. (10th December 2015)

• Record Type: Journal Article
• Authors: Zhang, Bin; Dhital, Sushil; Flanagan, Bernadine M.; Luckman, Paul; Halley, Peter J.; Gidley, Michael J.
• Is Part Of: Carbohydrate polymers. Volume 134(2015)
• Page Start: 485
• Page End: 496
• Publication Date: 2015-12-10
• Subjects: CP/MAS cross-polarized magic angle spinning -- DSC differential scanning calorimetry/calorimeter -- G50 gelose 50 -- NMR nuclear magnetic resonance -- LOS log of slope -- NMS normal maize starch -- SEC size exclusion chromatography -- SEM scanning electron microscope -- WMS waxy maize starch -- XRD X-ray diffractometry/diffractometer; High-amylose starch -- Extrusion -- In vitro digestion -- Enzyme-resistant starch -- Local molecular density; Polysaccharides -- Periodicals; Polysaccharides -- Periodicals; Polysaccharides -- Périodiques; Electronic journals; 547.78
• DOI: 10.1016/j.carbpol.2015.07.095
• Languages: English
• ISSNs: 0144-8617

Abstract

Highlights: Maize starches with different amylose contents extruded with only water. High-amylose extrudates have low digestion rate compared to cooked form. Extruded and cooked forms have similar structural order but different density. Local molecular density of low-order starch matrices can control digestion kinetics. Abstract: Waxy, normal and highwaymen maize starches were extruded with water as sole plasticizer to achieve low-order starch matrices. Of the three starches, we found that only high-amylose extrudate showed lower digestion rate/extent than starches cooked in excess water. The ordered structure of high-amylose starches in cooked and extruded forms was similar, as judged by NMR, XRD and DSC techniques, but enzyme resistance was much greater for extruded forms. Size exclusion chromatography suggested that longer chains were involved in enzyme resistance. We propose that the local molecular density of packing of amylose chains can control the digestion kinetics rather than just crystallinity, with the principle being that density sufficient to either prevent/limit binding and/or slow down catalysis can be achieved by dense amorphous packing.