ROLE OF PHOSPHORUS IN VISCOSITY, GELATINIZATION, AND RETROGRADATION OF STARCH

The effect of starch crystallinity and phosphorus on starch gelatiniza tion and retrogradation were studied using wide-angle X-ray powder dif fraction, cross polarization/magic angle spinning (CP/MAS) C-13 nuclea r magnetic resonance (NMR) spectroscopy, P-31 NMR spectroscopy, Rapid Visco Analyzer (RVA) and differential scanning calorimetry (DSC). Two starches differing significantly in peak viscosity (cv. Stephens, 283 BU; cv. Crew, 560 BU) were comparable in amylose content and starch cr ystallinity, while differing significantly in phospholipids content. S tarch of lower peak viscosity had a higher phospholipids content and s howed a slower rate of retrogradation. Starch from Stephens (0.098% ph osphorus) had an enthalpy value of retrograded starch of 2.2 J/g after 14 days of storage, while starch from Crew (0.062% phosphorus) had an enthalpy value as high as 4.4 J/g. Defatting with a hot n-propanol an d water (3:1) mixture caused substantial changes in peak viscosity. Pe ak viscosity for starch from Crew decreased by 75 RVU due to defatting , while starch from Stephens decreased by as much as 125 RVU. After de fatting with the hot n-propanol water mixture, the rate and extent of starch retrogradation were comparable between the prime starches, whic h differed significantly in peak viscosity.