Starch infrared radiation

It has been mentioned by Baly279 that, although carbohydrates do not selectively absorb ultraviolet and visible light, they do show selective absorption of infrared radiation in the wavelength range of 1.5-6 /im. This observation prompted Sem-mens280-281 to examine the action of polarized infrared radiation upon starch. She realized that mild hydrolysis takes place in starch subjected to such treatment, as well as to irradiation by nonpolarized infrared radiation. The effects of such radiation are observed in samples both in vitro and in vivo (namely in plants). 

The first result of applying infrared radiation to native starch is degradation. Schierbaum et al.u observed the sequence of dehydration, in which nonbonded water is driven off prior to capillary water (Fig. 30). The shape of the diagram suggests that the effects of heating are very mild. Thus infrared heating has the potential for subtle modifications of starch. The amounts of particular portions of water are obviously different for potato starch, cereal starches, and soaked starches. 

The effects of increased temperature (thermolysis) of starch by conventional heating have been reviewed.2 In the present article, the effects of freezing, as well as heating by infrared and microwave radiations, are described. 

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