Variability in starch rheological and thermal properties from commercial corn hybrids and its effect on food functional properties

The objectives of this research were to survey the variability in a sample set of commercial hybrids and then identify different hybrids to determine relationships between starch rheological characteristics and food characteristics. Fifty-nine commercial corn hybrids grown in the same year at the same location were wet milled using a 100g laboratory procedure; the resulting starch was analyzed to determine the variability in pasting, gel and thermal properties. A basic starch pudding was used as the food model for characterization of food pasting and gel strength properties. The researcher postulated that a five percent difference in final viscosity of the starch pasting properties would be the best predictor of a practical difference among food characteristics. The final viscosities of the commercial sample set varied from 1697 cP to 2064 cP. Five hybrids were selected to represent the final viscosity range and were tested for starch pasting properties (RVA), thermal properties (DSC) and gel strength properties (texture analysis). The final viscosities were positively correlated to both starch gel strength characteristics of initial rupture and gel strength at 7.5 mm depth with correlation coefficients of 0.88 and 0.77, respectively. The selected hybrids were also tested to determine pudding pasting properties (RVA) and pudding gel strengths (texture analysis). The final viscosity of the starches was positively correlated to the initial rupture gel strength of the pudding with a correlation coefficient of 0.71. A five percent difference in starch final viscosity made a measurable difference in pudding gel strength. The starch with the highest final viscosity made the firmest pudding. There can be a formula reduction of 10 percent starch for specific hybrids to obtain the same food textural properties that are produced by lowest gel strength forming starch.