Structural changes within the amorphous and crysalline domains of c-type starches subjected to heat moisture treatment at different temperatures

Ambigaipalan, Priyatharini (2013) Structural changes within the amorphous and crysalline domains of c-type starches subjected to heat moisture treatment at different temperatures. Doctoral (PhD) thesis, Memorial University of Newfoundland.

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Abstract

The structure (granular, supramolecular, molecular) and physicochemical properties of starches isolated from newly introduced Canadian cultivars of faba bean (FB), black bean (BB) and pinto bean (PB) were examined. The structure and physicochemical properties were determined by microscopy, High performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD), Attenuated total reflectance Fourier transform infra-red spectroscopy (A TR-FTIR), Wide angle X-ray diffraction (WAXS), ¹³C cross polarization magic angle spinning nuclear magnetic resonance (¹³C CP/MAS NMR), Differential scanning calorimetry (DSC), Rapid visco analyzer (RVA), susceptibility towards enzyme and acid hydrolysis and turbidity. FB starches exhibited cracked granules, whereas the surface of PB and BB starches showed no evidence of cracks or indentations. All starches exhibited a 'C' type X-ray pattern. Molecular order near the granule surface followed the order: BB~PB>FB. Differences in amylopectin chain length distribution among FB, BB and PB starches and among cultivars were marginal. FB starches significantly (P<0.05) differed from BB and PB starches with respect to amylose leaching, swelling factor, gelatinization temperatures, enthalpy of gelatinization, susceptibility towards acid hydrolysis and nutritional fractions. Retrogradation characteristics of FB, BB and PB starches monitored by turbidity, FTIR, DSC, ¹³C CP/MAS NMR and X-ray followed the order: FB>BB~PB, PB>BB>FB, PB~BB~FB, PB~BB~FB and PB~BB~FB, respectively. Retrograded FB starches were hydrolyzed by α-amylase to a greater extent than BB and PB (BB>PB) starches.

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