87th AACC Annual Meeting
Montréal, Québec, Canada
October 13-17, 2002
Palais des Congrès
Novel techniques to evaluate starch gelatinization in several Mexican corn races. R. A. S. MAURICIO, J. D. C. Figueroa, A. G. Mendoza, E. S. Morales, and M. M. Gaytán. Centro de Investigación y de Estudios Avanzados del IPN, Unidad Querétaro, Libramiento Norponiente 2000, Real de Juriquilla, Qro., Mex. 76230.
The aim of this work was to study the starch gelatinization of Mexican corn races using four analytical techniques. Of special interest was to obtain the relation between kernel texture and kernel performance during processing, with the final use of those races. Two important techniques, DSC and RVA, widely used in starch characterization, were considered in this work to evaluate ohmic cooking (OC) and low frequency impedance measurements (LFIM), as novel and alternative techniques for such purpose. RVA data showed that corn races with floury endosperm (CFE) developed higher peak viscosities (450 RVU's) than those of corn with hard endosperm (CHE) where the peak viscosity decreased to 22 RVU's. On the other hand, the DSC data showed onset temperatures of about 64 and 69°C, for CFE and CHE, respectively. The experimental data from LFIM and OC show characteristics clearly attributable to the gelatinization process. In particular, the gelatinization temperatures obtained from DSC and LFIM show a highly significant correlation of 0.87 (p < 0.01). On the other hand, the peak viscosity of RVA measurements showed a good correlation (0.574, p < 0.05) with the change in the electrical current detected by OC during gelatinization. In conclusion, with the four techniques studied it was possible to evaluate the gelatinization of starch, being LFIM the technique with more resolution. The four techniques considered allow the determination of the type endosperm, the thermal properties of Mexican corn starch, and the final use in the food industry.
The American Association of Cereal Chemists