The influence of ethanol concentration on content of total and individual phenolics in walnut alcoholic drink
2008
Jakopic, J. | Solar, A. | Colaric, M. | Hudina, M. | Veberic, R. | Stampar, F.
The influence of the ethanol concentrations on the phenolic content was analysed in walnut liqueur, which is traditionally prepared from green walnut fruits. At the end of June, green walnut fruits from cultivars Elit and Franquette were picked and steeped into three concentrations (40, 60 and 96%) of ethanol. In the walnut alcoholic drink (liqueur), total phenolic content was measured using spectrophotometer. Furthermore, twelve individual phenolics were investigated using HPLC with PDA detector such as gallic, protocatechuic, syringic, ellagic, sinapic, <i>p</i> -coumaric, chlorogenic, vanillic and caffeic acid, (+)-catechin, 1,4-naphthoquinone and juglone. The content of total phenolics increased with increasing ethanol concentration. Similar results were achieved for some individual phenolic compounds such as protocatechuic, sinapic and <i>p</i> -coumaric acid as well as 1,4-naphthoquinone. The levels of some other phenolic content were highest at 40% ethanol and lowest at 96% ethanol. This was exhibited for gallic, chlorogenic, vanillic and syringic acid, (+)-catechin and juglone.
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