Retrogradation characteristics of pulse starches

- Retrogradation monitored by X-ray, FTIR, DSC,13CCP/MAS NMR, turbidity & amylolysis.
- DSC, NMR, turbidity & amylolysis showed no difference in retrogradation order.
- Retrogradation order was different when assessed by FTIR, turbidity and amylolysis.

The retrogradation characteristics of pulse starches (C-type) isolated from genotypes of Faba bean [FB], Black bean [BB] and Pinto bean [PB] were determined by a multi-technique approach. The study showed that the rate and extent of retrogradation monitored by Turbidity, Fourier transform infra-red spectroscopy (ATR-FTIR), Differential scanning calorimetry (DSC), 13C cross polarization magic angle spinning nuclear magnetic resonance (13C CP/MAS NMR), Wide angle X-ray diffraction (WAXS) and susceptibility towards hydrolysis by porcine pancreatic α-amylase followed the order: FB > BB ~ PB, PB > BB > FB, PB ~ BB ~ FB, PB ~ BB ~ FB, PB ~ BB ~ FB and PB > BB > FB, respectively. Difference in retrogradation order is indicative that each technique measures a different process of recrystallization and reflects the interplay among the following factors: 1) amount of amylose leached during gelatinization, 2) interactions between amylose-amylose (AM-AM) and amylose-amylopectin (AM-AP) chains and 3) segmental mobility of AM and AP chains.