AbstractProof for Irradiation of Starch. Working Rules and Application to Various Starches. The test which is proposed for the proof of irradiation of starch is based on the determination of the malonaldehyde – which is formed by irradiation – by means of 2‐thiobarbituric acid. The study was made on the alteration of the aldehyde content of 3 starches (maize starch, pregelatinized maize starch, potato starch) which had been irradiated with 400 Krad and stored at different temperatures. If water content of the sample, storage temperature and duration of storage are known, the original irradiation dose can be calculated by the obtained graphs. These calculations are of variable precision in the specific cases. It is possible to determine the irradiation of maize starch having been stored for three months at 25 °C, provided that the irradiation dose had been of at least 2