Detection of changes during heat

Earfy Detection of Changes During Heat Processing and Storage of Tomato Products... 

In ink compositions a compound can be introduced that imdergoes a retro-Diels-Alder reaction with color change during heating. This color change can be used for detecting the heat history of an article (20). 

Direct kinetic measurements from the changes in diffracted beam intensities with time during heating of the reactant are illustrated in the work of Haber et al. [255]. Gam [126] has reviewed the apparatus used to obtain X-ray diffraction measurements in thermal analysis. Wiedemann [256] has designed equipment capable of giving simultaneous thermo-gravimetric and X-ray data under high vacuum. X-Ray diffraction studies enable the presence, or absence, of topotactic relationships between reactant and product to be detected [92,102,257—260], Results are sometimes considered with reference to the pseudomorphic shape of residual crystallites. 

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