Phase transitions in the starch-water system studied by adiabatic scanning calorimetry.
We report high-precision measurements of phase transitions in the starch-water system by using for the first time adiabatic scanning calorimetry (ASC). Potato starch and nixtamalized corn flours were studied by this technique as a function of the moisture content. We calculated the percentage of gelatinized starch granules, as a function of the temperature, for both flours. For bi-phasic behavior in potato starch, at intermediate water contents, we propose an explanation based on previous hypotheses and on the experimental behavior as deduced from ASC measurements. ASC results suggest, in the case of nixtamalized corn flour, that uniform moisture is present in corn starch granules for all the considered moistures. A shift to higher temperatures of the peak temperature is observed when comparing the c(p)(T) curves with the classical DSC endotherms as measured for this flour. For both flours we estimated from the ASC results the melting temperatures of the starch granules, at zero moisture content, by using Flory's equation.
Cruz-Orea
Alfredo
A
Laboratorium voor Akoestiek en Thermische Fysica, Departement Natuurkunde, Katholieke Universiteit Leuven, Celestijnenlaan 200 D, B-3001 Leuven, Belgium. orea@fis.cinvestav.mx
Pitsi
Guido
G
Jamée
Peter
P
Thoen
Jan
J
D002152:Calorimetry, Differential Scanning; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D003460:Crystallization; D004040:Dietary Carbohydrates; D005511:Food Handling; D005782:Gels; D006358:Hot Temperature; D011198:Solanum tuberosum; D013213:Starch / Q000737:chemistry*; D013816:Thermodynamics; D014867:Water; D003313:Zea mays
D004040:Dietary Carbohydrates; D005782:Gels; D014867:Water; D013213:Starch