Abstract
A study for determination of the volatile composition of distillates with the addition of 50% and 70% ethanol extracts of St. John's wort (Hypericum perforatym L) was conducted. The extracts were added in amounts of 20, 80, 100, 200, 400 and 600 ml. The remaining amount to liter was pure distillate obtained from the grapes of the variety “Melnik-55”. Gas chromatographic (GC-FID) analysis for identification and quantification of the volatile components in the distillates obtained was performed. Various compounds from the groups of esters, higher alcohols, aldehydes and terpene alcohols have been identified. The methanol levels were found to be highest in the control sample (364.74 ± 0.32 mg/dm3) and proportionally decreased with increasing of the fraction of added extract in the experimental variants. This contributed to obtained of the alcoholic distillate with decreased methanol content. A similar decrease in the amounts of acetaldehyde and ethyl acetate was observed. This reduced the harmful aromatic nuances that these compounds impart when they were in higher amounts. Four major higher alcohols have been identified - 3-methyl-1-butanol, 2-methyl-1-butanol, 2-butanol and 1-propanol. The ester composition was diverse, quantitatively dominated by the presence of ethyl acetate. A higher total terpene content was detected in the samples with the addition of Hypericum perforatym L extract compared to the control. This indicated increased final concentrations in the distillates (a consequence of the terpene composition of the herb), which may intensify its biological effect. The produced distillates with added extracts of Hypericum perforatym L can be used for obtaining of new higher alcoholic beverages with added medicinal herb extracts.
Highlights
Modern focus in the work of various scientific groups is the search for solutions to improve the quality and health characteristics of foods by adding different plant extracts in them (Ivanov et al, 2014; Petkova et al, 2014; Stoilova et al, 2007)
The substitution of parts of the distillate with ethanol extracts (50% and 70%) of Hypericum perforatym L resulted in a reduction of the levels of methyl alcohol in the final distillate
All established methanol levels in the samples were within its tolerable level, a reduction in methanol levels was reported when extracts were incorporated, which contributed to the decreased methanol content of the distillate
Summary
Modern focus in the work of various scientific groups is the search for solutions to improve the quality and health characteristics of foods by adding different plant extracts (with high biological activities) in them (Ivanov et al, 2014; Petkova et al, 2014; Stoilova et al, 2007). The dominant ester is ethyl acetate, which according to the author is in the range of 420.00 - 700.00 mg/dm3 The aldehydes are another group of compounds that have a significant effect on the aromatic matrix of distillates. The main importance is their role as a precursors to the esterification process in which they interact with acids to form esters with significant aromatic influence (Chobanova, 2012; Yankov et al, 2000) Another group of compounds involved in the volatile composition and aromatic matrix of distillates are terpenes. Dominant in this group are terpene alcohols linalool, geraniol, α-terpineol, nerol and β-citronellol (Lengyel, 2012) They are responsible for the fruity aromatic nuances, which is especially important when fermenting grapes from muscat grapevine varieties (Luan et al, 2006). The aim of this study is to define the volatile composition of grape distillates with added extracts of Hypericum perforatym L
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