Quality characteristics of spirit drinks based on fruit distillates are formed mainly due to the concentration and the ratio of aroma-forming volatile components, part of which is transferred to a product from the initial raw materials. Analysis of data on the biochemical composition of the individual types of stone raw materials makes it possible to substantiate scientifically the regime parameters of the individual production stages and allows revealing adulteration. The present review considers questions concerning the search of chemical markers for fruit vodkas made on the basis of distillates from plum, cherry plum, cherry, sweet cherry, apricot and peach. The data are presented on the content of reducing sugars, titratable acidity, free amino acids, pH and sugar-acid index of the fruit raw materials under consideration. Significant variations of these indices depending on a raw material type and region of cultivation are shown. The questions of evaluation of the pectin complex in the individual types of stone raw materials are considered. The scheme of hydrolysis of pectin substances of fruit raw materials occurring at the stage of its preparation for distillation is presented. An important role of this process in formation of quality characteristics of fruit distillates and spirit drinks on their basis (fruit vodkas) is shown. The data on the composition and concentration of aroma-forming volatile components of individual types of stone raw materials are given. The data on the main physico-chemical characteristics of aroma-forming volatile components found in the fresh fruit types under consideration and methods for their analysis are presented. The generalized estimation of technological peculiarities of preparation of individual types of fruit raw materials for fermentation and distillation depending on their biochemical composition is given. In general, analysis of the data presented in this review allowed making a conclusion about prospects of investigations aimed to the development of identification indices of fruit distillates and fruit vodkas using the primary aroma-forming volatile components of raw materials.

Grain bran is used mostly in animal farming and food industry. However, grain bran can also serve as an alternative source of nitrogenous substances in distillate technology. The present research objective was to study the complex of water-soluble nitrogenous compounds in grain bran and to identify the effect of the bran type and its granulometric characteristics on their composition and concentration. The research featured 30 industrial grain samples of wheat, rye, and triticale, as well as the corresponding bran samples. The total protein was determined by the Kjeldahl method, the size modulus – by sieving. In the bran aqueous phase, the protein content was measured using the Lowry method, the amine nitrogen content – by the copper method, and the free amino acid content – by the high-performance liquid chromatography. In bran, the content of total protein increased by 16–28%, the proportion of water-soluble forms of nitrogenous compounds increased by 6–29%, and the free amino acids increased by 1.4–2.3 times, if compared with the grain samples. The proportion of soluble proteins in the rye bran was 15–30% higher than in other types. The types of bran had a different content of individual amino acids. A high correlation was observed between the modulus of the bran size, the mass concentration of soluble proteins, and the free amino acids. The proportion of soluble proteins reached 44.1% as the size modulus decreased. The samples of rye bran demonstrated the maximal growth of this indicator. Bran, regardless of the type of raw material and particle size distribution, had a higher concentration of free amino acids in comparison with the original grain. The experiment revealed the following linear dependence: the proportion of free amino acids in bran increased by 46–54% as the size modulus decreased by 0.72–0.85. The article introduces linear dependence equations for each type of bran, as well as the percentage of free amino acids for the change in the size modulus per unit. Aqueous extracts of small-size rye grain bran proved to have good prospects for distillate technology. According to the evaluation of the nitrogen-containing complex of various grain bran types, small-size rye bran had more advantages in terms of soluble protein forms and free amino acids. Further research will feature the fermentation activity of yeast in distillate production to develop specific sensory properties.

The  development of reliable identification criteria for various  types of foods,  including fruit  vodkas,  is one  of the top-priority directions of scientific research in the field of quality control. The review examines different approaches to solution to a problem of searching identification criteria for fruit vodkas that will allow differentiating products by a type of fruit  raw materials, their grade  and region of origin.  To this  end, instrumental methods of analysis were used, including spectral, high performance liquid chromatography (HPLC) and gas chromatography coupled to mass  spectrometry (GC–MS) as the  main  method. When  detecting minor  aroma-forming substances using  the  latter method, it is necessary, first  of all, to  carry  out  the  special  sample preparation that includes extraction and  concentration of target substances. The  present review  examines three main  types of sample preparation (liquid  extraction, solid-phase extraction, supercritical fluid extraction) and  modifications of these methods. Their  comparative analysis was carried out  with  respect to  labor  intensity, extraction effectiveness, volatile aroma-forming compounds significantly different by polarity, reproducibility and  sustainability. It has been  shown  that a type of sample preparation affects  reproducibility and sensitivity of an instrumental analytic method, which is especially important for identification of some  minor  compounds, which concentration can be regarded as indicators for identification of fruit  raw materials. It has been  concluded that among  the  examined methods of sample preparation, the most  promising for the development of identification criteria for fruit vodkas is headspace solid-phase microextraction (HS-SPME) as this  method is highly  effective in terms of extraction of target components including minor.