HPLC DETERMINATION OF THIOL-CONTAINING ANTI-BROWNING ADDITIVES IN FRUIT AND VEGETABLE PRODUCTS

The HPLC determination of residual thiol-containing anti-browning addi tives (cysteine, N-acetyl-cysteine and reduced glutathione) in treated fruit and vegetable products using the Ellman's reagent (5,5'-dithiob is(2-nitrobenzoic acid); DTNB) is described. The thiols were isolated by extraction with solvent containing NaF, EDTA, acetic and ascorbic a cids and derivatized with the Ellman's reagent in an aqueous medium at pH 8.0. The resulting disulphides were determined by reverse phase HP LC with mobile phase consisting of methanol and phosphate buffer pH 7. 5. The UV-detection at 330nm was used. The optimal extraction and deri vatization conditions were found and the method was used to determine the residual concentrations of thiols in potato, avocado, apple and ba nana purees, sliced mushrooms and frozen basil treated with cysteine.