Influence of processing variables on some characteristics of nocino liqueur

The production of nocino, an after-dinner liqueur of Celtic origin, is connected with ancient superstitions and legend. The date upon which the walnuts should be gathered (the night of 24 June) seems to be one of the few universally accepted features of the production process. The aim of this study was to investigate the influence of the relative ripeness of the walnuts, together with the effect of temperature and the length of steeping on the phenolic composition and the antioxidant power of nocino. Three different batches of unripe walnuts gathered from a single nut tree were used to produce 18 samples of alcoholic infusion. The steeping process was carried out at 20 or 40 °C, for 15, 40 or 90 days. The results revealed that the highest content of phenolic substances - and consequently the highest antioxidant power - was obtained with the least ripe batch of walnuts. On the other hand, temperature and length of steeping have little effect on the phenolic composition of nocino.