title: Comparative study of the retrogradation of intermediate water content waxy maize, wheat, and potato starches.
abstract: The retrogradation of extruded starches from three different botanical sources was studied in concentrated conditions (34 +/- 1% water) at 25 degrees C using differential scanning calorimetry (DSC) and isothermal calorimetry, Fourier transform infrared spectroscopy (FTIR), and wide-angle X-ray scattering. Potato starch showed the highest rate of retrogradation (approximately 0.17 h(-1)) followed by waxy maize (approximately 0.12 h(-1)), while the retrogradation of wheat starch was the slowest (approximately 0.05 h(-1)). In addition to the kinetics, the extent of molecular order in the retrograded samples was studied in detail in terms of "short-range" (helical) and "long-range" (crystalline) distance scales. The amylopectin crystallinity indices were essentially the same (approximately 47-51% amylopectin basis) for the three starches. However, significant differences were found in the enthalpy of melting measured by DSC after "full" retrogradation (potato, 11.6 +/- 0.7; waxy maize, 9.0 +/- 0.5; and wheat, 6.1 +/- 0.3 J/g of amylopectin). The degree of short-range molecular order in the retrograded state determined by FTIR was waxy maize > potato > wheat. The effect of amylopectin average chain length and the polymorphism of the crystalline phase were taken into account to explain the differences in the retrogradation enthalpies.
authors.affiliation: Division of Food Sciences, School of Biosciences, University of Nottingham, Loughborough LE12 5RD, United Kingdom.
authors.forename: Marie-Astrid
authors.initials: MA
authors.lastname: Ottenhof
authors.forename: Sandra E
authors.initials: SE
authors.lastname: Hill
authors.forename: Imad A
authors.initials: IA
authors.lastname: Farhat
mesh_terms: D000687:Amylopectin / Q000032:analysis; D002152:Calorimetry, Differential Scanning; D003460:Crystallization; D011198:Solanum tuberosum / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D013213:Starch / Q000737:chemistry*; D013816:Thermodynamics; D014908:Triticum / Q000737:chemistry*; D014867:Water / Q000032:analysis*; D014961:X-Ray Diffraction; D003313:Zea mays / Q000737:chemistry*
chemical_list: D014867:Water; D013213:Starch; D000687:Amylopectin