Traditional walnut liqueur – cocktail of phenolics

The phenolic composition in walnut husks of the Slovenian cultivar Elit, which is a basic material for the traditional making of walnut liqueur, was investigated by HPLC with a PDA detector. Four different samplings of green husks were performed on different dates in order to compare the contents of phenolic compounds. The 2nd sampling coincided with the picking time of walnut fruits intended for the making of liqueur. Phenolic composition of walnut liqueur was investigated as well. Thirteen phenolic compounds were identified in walnut husks: chlorogenic acid, caffeic acid, ferulic acid, sinapic acid, gallic acid, ellagic acid, protocatechuic acid, syringic acid, vanillic acid, catechin, epicatechin, myricetin, and juglone. In walnut liqueur, 1,4-naphthoquinone was also identified. The major phenolic in the husks was juglone with the highest content in the 2nd sampling; its content in walnut liqueur was low. The concentrations of individual phenolics in the liqueur were quite low compared with the contents in the green husks, due to the traditional way of making the liqueur.