THE CARRY-THROUGH OF RESIDUES OF MALEIC HYDRAZIDE FROM TREATED POTATOES, FOLLOWING MANUFACTURE INTO POTATO CRISPS AND JACKET POTATO CRISPS

Potatoes, which had been treated 'in the field' with a commercial form ulation of maleic hydrazide, were processed into potato crisps and jac ket potato crisps on a factory production line using standard manufact uring conditions. Samples were taken at strategic points throughout th e process and analysed to determine the degree of carry-through of res idues. Results demonstrated that ca 56% of the maleic hydrazide residu e in a potato could be carried through into the potato crisps, irrespe ctive of which type of crisp was being manufactured. Results from a si milarly constructed study investigating the fate of pesticides applied post-harvest showed that carry-through was less than 10%. This differ ence is explained in terms Of the different modes of action of the two classes of pesticides being investigated. It is known that, as maleic hydrazide is a systemic pesticide, it will be located within the fles h of the potato tuber and is therefore likely to be protected from the various stages of the crisping process. However, the post-harvest non -systemic pesticides are applied to the exterior surface of the tuber and are therefore not likely to be protected in the same way. The resu lts also showed that, due to the concentration effect caused by the lo ss of moisture during crisp manufacture, the levels of maleic hydrazid e residues in crisps (on a mg/kg product basis) were approximately twi ce those measured in the original potatoes.