Chemical profile of spirits obtained by spontaneous fermentation of different varieties of plum fruits

Abstract

The aim of this study was to characterize the chemical composition of plum spirits, derived from four varieties of plums (Wegierka Zwykla, Wegierka Dąbrowicka, Stanley and Cacanska Lepotica) after spontaneous fermentation. During fermentation, mashes were weighed daily to determine the weight loss. After fermentation, samples were distilled (simple and fractional) and analyzed using official, GC-FID and SPME–GC–MS methods. The obtained plum spirits differed significantly in chemical composition. Most favorable for the fermentation process were mashes obtained from Wegierka Dąbrowicka and Stanley plums, which contained relatively high levels of reducing sugars and free amino nitrogen, respectively. The best fermentation kinetics were shown by Stanley plum mashes, and the process lasted about 10 days. All fermented mashes were characterized by comparable consumption of sugars, from 96.1 to 97 %, and contained from 5.4 to 6.3 vol% ethanol. GC-FID and SPME–GC–MS analysis showed over 64 volatile components in analyzed plum spirits. In case of 24 of them the detected concentration exceeded odor threshold values in all samples. Six compounds (ethyl dodecanoate, benzyl acetate, methyl cinnamate, 1-heptanol, α-terpineol and benzothiazole) influenced the aroma of specific sample. The highest concentration of volatiles was found in Wegierka Zwykla spirits, including the highest levels of higher alcohols, ethyl hexanoate, ethyl octanoate, methyl dodecanoate, ethyl benzoate, 1-octanol, damascenone, α-terpineol, eugenol, 2-bornene, α-ocimene and others. Stanley spirits contained the lowest amounts of analyzed components quantitatively. All spirits gained similar scores in sensory evaluation—15.3–16.6 points.