Detection of Corn Starch Irradiated with Low Doses of Gamma Rays. Part II. Disappearance of Malonaldehyde from Starches of Various Moisture Contents

Using the thiobarbituric acid test for malonaldehyde, irradiated starch can be detected qualitatively for up to a year after irradiation. If the moisture content of the starch is known, the dose can be determined quantitatively, if below 75 krad, for up to four months after irradiation, and doses between 75 and 200 krad can be determined up to four weeks after irradiation. Decreasing production of malonaldehyde with increased moisture content is ascribed to preferential radilysis of the water rather than the starch, with formation of hydrogen peroxide. A possible route for the disappearance of malonaldehyde by reaction with hydrogen peroxide is suggested.