Cereal Chem. 73 (3):297-301 |
Starch Gelatinization Measured By Pulsed Nuclear Magnetic Resonance.
C. E. Mendes Da Silva (1), C. F. Ciacco (2), G. E. Barberis (3), W. M. R. Solano (3), and C. Rettori (3). (1) Department of Food Technology, Universidade Federal do Ceará, Fortaleza, CE, Brazil--CEP: 60021-970. Fax: 55-85-2889752. (2) School of Food Engineering, Unicamp, Campinas, Sao Paulo, Brazil--CEP: 13083-970. (3) Physics Institute, Unicamp, Campinas, Sao Paulo, Brazil--CEP: 13083-970. Accepted December 11, 1995. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. American Association of Cereal Chemists, Inc., 1996.
The extent of starch gelatinization was quantified by pulsed-proton nuclear magnetic resonance (NMR) analysis. To quantify the gelatinization of starch, a relative liquefying index (RLI), calculated from the ratio of liquid to solid phases determined by pulsed NMR, was defined. A correlation coefficient >0.94, at 5% significance level, was found between the RLI and the degree of gelatinization determined by a method of enzymatic susceptibility. Studies on the kinetics of gelatinization of wheat starch in starch-water systems by the NMR method showed a first-order reaction until the degree of gelatinization reached a fixed and constant value, which increased with the temperature and with the amount of water in the system. The minimum activation energy occurred at 45.0% water. The similarity between the activation energies found at 55.0 and at 65.0% water indicated that 55.0% water is the minimum water content for the complete gelatinization of wheat starch.