Ml. Fishman et Pd. Hoagland, CHARACTERIZATION OF STARCHES DISSOLVED IN WATER BY MICROWAVE-HEATING IN A HIGH-PRESSURE VESSEL, Carbohydrate polymers, 23(3), 1994, pp. 175-183
Starch granules derived from four corn varieties were dispersed in wat
er and depending on variety about 49-71% of the granules dissolved by
microwave heating in a high pressure vessel (MWHPV). The apparent rati
os of amylopectin to amylose were 1:0, 3:1, 1:1 and 3:7. High performa
nce size exclusion chromatography (HPSEC) was carried out using two mu
Bondagel(dagger) and one Synchropak(dagger) HPSEC columns placed in s
eries. These had size exclusion limits specified by their manufacturer
s as 400 nm, 100 nm, and 10 nm, respectively. The mobile phase was 0.0
5 M NaNO3. For each starch composition, refractive index and viscosity
chromatograms were obtained and fitted with the same six Gaussian com
ponents by nonlinear regression analysis. Calibration of the column se
t with pullulan and dextran standards in hydrodynamic volume and root
mean square radius of gyration (R(g)) enabled calculation of the intri
nsic viscosity (IV), molecular weight (M), and R(g) for each component
in addition to global values of these quantities for the entire distr
ibution. Analysis of the data revealed that as starches eluted from th
e column set, there were large changes in M and R(g) and rather small
changes in IV. Furthermore, MWHPV containing water as employed here pr
oduces starch of relatively large molecular weight and size but low in
trinsic viscosity leading to the conclusion that dense starch granule
fragments were solubilized.