ANALYTICAL CONTROL OF THE TOTAL VOLATILE BASES NITROGEN IN FISH PRODUCTS

Comparative studies of the content of total nitrogen of volatile bases (ALO) in fish raw materials, as an objective indicator of quality, were carried out by direct distillation of the sample and by distillation of acid extract. It was found that the method based on direct distillation of the sample results in 25-30% higher values than the method of acid extract distillation due to alkaline hydrolysis of the sample protein. A comparison of the reproducibility of the two methods using the Fisher statistical criterion showed the heterogeneity of the variances and the impossibility of attributing them to a single general population. For the gradation of the quality of fish raw materials, the method of distilling acid extract is recommended. The objects of three different categories are studied, grouped according to the proposed three degrees of quality, based on the maximum permissible levels of nitrogen content of volatile bases. The reliability of the results is shown and a conclusion is made about the use of the ALO content as an indicator characterizing both the initial state of fish raw materials and the dynamics of the storage process and the establishment of the moment of spoilage. A method for measuring the mass fraction of total nitrogen of volatile bases has been developed and certified (certificate of certification No. 0168/ROSS RU.0001.310430/2020).

Influence of the Regime Parameters of Distillation on the Distribution of Volatile Components by Fractions in the Production of Cornel Distillate

На качество фруктовых дистиллятов оказывают существенное влияние различные физико-химические процессы, проходящие в дистилляционной установке под действием высокой температуры. В зависимости от особенностей биохимического состава для каждого вида сырья необходимо подбирать конкретные режимы дистилляции, обеспечивающие получение дистиллята с высокими органолептическими и физико-химическими характеристиками. В связи с этим цель работы состояла в исследовании влияния режимных параметров фракционированной дистилляции сброженной кизиловой мезги на распределение летучих компонентов по фракциям. В качестве объектов исследования в работе использовали фракции, полученные в процессе дистилляции сброженной кизиловой мезги на установке прямой сгонки «Kothe Distillationstechnik» (Германия). Экспериментально установлено, что повышение скорости при дистилляции сброженной кизиловой мезги приводит к увеличению объема отбираемой головной фракции, при одновременном снижении ее крепости. Показано, что изменение скорости дистилляции приводит к изменению характера перехода основных летучих компонентов в дистиллят и распределения их по фракциям. Изучена динамика перехода летучих компонентов в дистиллят при различных режимах работы дистилляционной установки - без задержки флегмы (обычный режим) и с задержкой флегмы на нижней тарелке укрепляющей колонны. Проведенные исследования показали, что при условии медленной дистилляции со скоростью не более 5,5 см3/мин в средние фракции переходит 82-85% компонентов энантового эфира, а содержание ацетальдегида снижается на 10-12% по сравнению с быстрой дистилляцией. Показано, что применение задержки флегмы на нижней тарелке укрепляющей колонны дистилляционной установки также способствует снижению перехода в кизиловый дистиллят ацетальдегида и этилацетата, и к сокращению потерь компонентов энантового эфира с головной и хвостовой фракциями. The quality of fruit distillates is significantly affected by various physical and chemical processes that take place in the distillation unit under the influence of high temperature. Depending on the characteristics of the biochemical composition for each type of raw material, it is necessary to select specific distillation modes that ensure the production of distillate with high organoleptic and physico-chemical characteristics. In this regard, the aim of the work was to study the influence of the regime parameters of fractionated distillation of fermented Cornel pulp on the distribution of volatile components by fractions. The fractions obtained during the distillation of fermented Cornel pulp at the direct distillation unit «Kothe Distillationstechnik» (Germany), were used as the objects of research. It is experimentally established that an increase in the speed during distillation of fermented Cornel pulp leads to an increase in the volume of the selected head fraction, while reducing its strength. It is shown that a change in the distillation rate leads to a change in the nature of the transition of the main volatile components to the distillate and their distribution by fractions. The dynamics of the transition of volatile components to distillate under different operating modes of the distillation unit - without phlegm delay (normal mode) and with phlegm delay on the lower plate of the reinforcing column is studied. Studies have shown that under the condition of slow distillation at a speed of no more than 5.5 cm3/min, 82-85% of the enantium ether components pass into the medium fractions, and the content of acetaldehyde decreases by 10-12% compared to fast distillation. It is shown that the use of phlegm delay on the lower plate of the strengthening column of the distillation unit also helps to reduce the transition to the Cornel distillate of acetaldehyde and ethyl acetate, and to reduce the loss of the components of the enantium ether with the head and tail fractions.

FORENSIC INVESTIGATION OF PETROLEUM COMPONENTS OF MIXED MOTOR GASOLINES

The main types of petroleum components that are used in the manufacture of mixed motor gasolines are considered. For the manufacture of mixed motor gasolines, a low-octane base is used, to which high-octane components are added. In many cases, reformate (catalytic reforming gasoline) and isopentane (isopentane fraction) are used as high-octane components of mixed motor gasolines. Straight-run gasoline and stable gasoline are often used as the low-octane gasoline base of blended automobile gasolines. Reformate is a liquid mixture of aromatic and saturated hydrocarbons used as a high-octane component of automobile (aviation) gasolines and raw materials in the production of aromatic hydrocarbons (arenas). The reformate is obtained by catalytic reforming of straight-run gasoline fractions. Isopentane (2-methylbutane (CH3)2CHCH2CH3) is a colorless, flammable liquid. The technical product is a mixture of isomeric pentanes and boils within 24 - 34°C. The isopentane fraction can be isolated from gas gasoline, from gasoline direct distillation of oil and gasoline catalytic cracking. Straight-run gasoline (nefras) is obtained from the processing of crude oil or gas condensate, oil shale or coal, natural gas or oil and gas. Straight run gasoline contains light gasoline fractions of direct distillation of oil with a boiling range of 35 - 180°C. Gas gasoline (gas stable gasoline) is obtained from natural and petroleum gases containing vapors of gasoline hydrocarbons. To separate them, the gases are compressed and cooled (compression method) or absorbed with oil or activated carbon. Gas gasoline is similar in chemical composition to straight-run gasoline, but contains lighter hydrocarbon fractions. The article discusses the results of a study of the listed petroleum components of mixed gasoline by gas-liquid chromatography. This method allows you to establish the qualitative and quantitative composition of mixed motor gasolines and their components. It is shown that from readily available petroleum components (isopentane fraction, aromatic hydrocarbons and gas stable gasoline) without the use of sophisticated technological equipment, a gasoline mixture with high detonation resistance, which is falsified automobile gasoline, can be obtained by mixing method. When mixed in certain proportions of reformate, isopentane fraction and gas stable gasoline, it is possible to obtain marketable gasoline that will meet the requirements of regulatory documents for gasoline. The considered technology allows, when mixing commodity gasolines A-92 (A-95) with reformate, isopentane fraction and gasoline gas stable in the calculated proportions, to improve the operational characteristics (detonation resistance) of the obtained gasoline mixture or to increase the volume of the obtained gasoline mixture without improving its performance.

Influence of the type of yeast on quality of cider material

Scientific research aimed at improving the quality of products is one of the most important tasks nowadays. It has been established that the use of pure yeast cultures promotes faster and fuller fermentation of sugars and improves the subsequent taste and aromatic characteristics of the product in comparison with wild forms. However, pure yeast cultures may differ in terms of fermentability of the wort. In this work the possibility of improving the quality of cider materials with the help of selecting the necessary strain of wine yeast is studied. Twelve yeast species of different strains, producers and price categories were studied. Apple wort was obtained from apples grown in the Samara region. The quality of apples was in accordance with the requirements of GOST 27572-87. The processing of apples was conducted under semi-industrial conditions. Fermentation of wort and storage of obtained cider materials were carried out at a temperature of 14–15 °C. The quality indicators of the dry table cider materials obtained met the requirements of GOST 31820-2015 for all major quality indicators. Сidеr distillates were obtained from wine materials by direct distillation and subjected to gas chromatographic analysis. According to the content of volatile components, all samples comply with the requirements of GOST R 51300-99. Based on the analysis of the rate of fermentation, flocculation and the production of volatile components, the best Vitilevure 58W3 (sample No. 4), Vitilevure Multiflor (sample No. 5) and LALVIN QА23 (sample No. 6) were selected. It was concluded that it is possible to improve the quality of cider materials by first selecting the most suitable yeast strain for the specific conditions. The obtained data can be used in production to improve the quality and increase the rate of fermentation of cider materials.

INFLUENCE OF THE TYPE OF YEAST ON QUALITY OF GRAPE WINE MATERIAL

Рассмотрена возможность повышения качества виноматериалов с помощью подбора штамма винных дрожжей. Исследовано 12 штаммов дрожжей различных производителей и ценовых категорий. Виноградное сусло получали из белого винограда технического сорта Цитронный Магарача, выращенного в Самарской области. Качество винограда соответствовало требованиям ГОСТ 31782–2012. Переработку винограда вели в полупромышленных условиях по «белому» способу. Дозировка дрожжей составляла 0,2 г/л. Брожение сусла и хранение полученных виноматериалов осуществляли при температуре 14–15°С. Показатели качества полученных сухих столовых виноматериалов удовлетворяли требованиям ГОСТ 32030–2013 по всем основным показателям. Из виноматериалов путем прямой перегонки получены винные дистилляты и подвергнуты газохроматографическому анализу. По содержанию летучих компонентов – метанола, сивушных масел, сложных эфиров, ацетальдегида, бензальдегида, кетонов все образцы соответствовали требованиям ГОСТ 31493–2012. Установлено, что по скорости сбраживания, флокулирующей способности и продуцированию летучих компонентов наилучшим для выбранного сорта винограда является штамм дрожжей Vitilevure DV10 (Danstar Ferment AG, Дания). Possibility of improvement of quality of wine materials by means of selection of a necessary strain of wine yeast is considered. 12 yeast strains of different producers and price categories were investigated. The grape mash was received from white grapes of a technical grade Tsitronnyy Magaracha who is grown up in the Samara region. The quality of grapes conformed to requirements of GOST 31782–2012. Processing of grapes was conducted in semi-industrial conditions on a white way. The dosage of yeast was 0,2 g/l. Fermentation of a mash and storage of the received wine materials carried out at a temperature of 14–15°C. Indicators of quality of the received dry table wine materials met requirements of GOST 32030–2013 for all key indicators of quality. From wine materials by direct distillation wine distillates was obtained and subjected to gas chromatographic analysis. According to the content of volatile components-methanol, fusel oils, esters, acetaldehyde, benzaldehyde, ketones, all samples met the requirements of GOST 31493–2012. It was found that the rate of fermentation, flocculating ability and production of volatile components is best for the selected grape variety strain Vitilevure DV10 (Danstar Ferment AG, Denmark).