The work provides up-to-date data on the taxonomic composition and quantitative indicators of zooplankton and zoobenthos communities of the Kama Reach of the Kuibyshev reservoir (within the Republic of Tatarstan) for the period from 2017 to 2022. According to the results of the conducted studies, zooplankton and zoobenthos in the considered water area were represented by 127 and 124 taxonomic units, of which 22 and 26 species were alien, respectively. Among planktonic invertebrates, rotifers prevailed both in species diversity and in numbers, and branched crustaceans in bio-mass. Diptera made a significant contribution to the formation of the species richness of zoobenthos, crustaceans dominated in number, and mollusks dominated in biomass. The structure-forming species in this water area were Rotifera Asplanchna priodonta (Gosse, 1850) and Brachionus angularis (Gosse, 1851), Cladocera Bosmina (Bosmina) longirostris (O.F. Müller, 1785) and Daphnia galeata (Sars, 1863), Amphipoda Cheli-corophium sowinsky Martynov, 1924 and the mollusk Dreissena bugensis (Andrusov, 1897). The role of alien species in quantitative indicators of zooplankton was insignificant, whereas in benthos they prevailed over native ones. An analysis of the structural indicators of planktonic and bottom communities revealed that their species diversity was characterized by relatively low values, both in abundance and biomass. At the same time, the components of communities as a whole developed equally, as evidenced by the obtained values of the equalization index. The ecological state of the considered groups of aquatic organisms was assessed as transitional from prosperous to stressful.

The article is devoted to the study of the prospects for using biodegradable collagen fiber as a sorbent. Recycling of fish scales has been carried out at the Department of Chemistry of Kaliningrad State Technical University, in an economically accessible way. The scales were washed with water with the addition of NaCl and Na2CO3 while heating. Centrifugation at 2347 RCF, drying and screening on sieves made it possible to obtain new collagen fiber of different fractions. The process of obtaining a collagen filter is described and its characteristics are indicated. The results of a field experiment on the filtration of water from an urban watercourse in Kaliningrad using the sorption filter under study are presented. A comparative analysis of the organoleptic and physicochemical parameters of the studied water sample before and after filtration has been carried out. Adsorption capacity has been assessed using several parameters. Analysis of the filtrate showed that precipitation of ions occurs Na+, SO42-, Cl-, HCO3-; biogenic elements in molecular and ionic form SiO2, NH4+, NO3-, total mineralization decreases by more than 3 times. The organoleptic characteristics of filtered water have significantly improved: transparency, color and smell. The obtained data are presented in comparison with the aquatic environment taken from the Kaliningrad watercourse. The selective properties of the collagen filter have been revealed. It has been shown that the use of collagen fiber is effective for purifying aqueous media and can be recommended for creating biodegradable filters for liquid fractions. A methodological success is the substantiation of the possibility of using natural secondary raw materials to reduce the environmental problems of storing and processing fibrillar proteins of hydrobiont scales.

In regions with extreme climates, plantings are the most important ecological element. The Volgograd region is characterized by low forest cover: with a total area of 113 thousand km, only 4.3% of the territory belongs to natural forests her. In the regional center, green zones are allocated no more than 15.0%. At the same time, natural plantings in the city are confined to ravines, gullies, small riverbeds, etc. The study of the diversity and assessment of the condition of woody plants in these conditions is becoming very relevant. The presented materials illustrate the current state of plantations in the floodplains of small rivers and gullies within the city limits of Volgograd. Model plots with an area of 0.01 km2 were identified within these stands, the total number of examined plants was 539. During the observations, the species composition has been revealed, the number of woody plants has been determined, the predominant species are highlighted. The plants have been classified into two groups: indigenous and invasive to the research region. Invasive plant species have been evaluated with the assignment of an invasive status to each of them according to the method of Sagalaev V. A. (2013). An ecological assessment of the species diversity and numerical abundance of woody plants has been carried out. The main tree species have been assessed according to the level of viability, taking into account the anthropogenic impact on the model sites. It has been revealed that natural ravine-girder plantings in urban conditions are not stable, there are a large number of weakened trees in each planting, individual species are classified as severely damaged by their condition. On the vital condition of both the planting as a whole and individual tree species are influenced by a complex of factors, including and anthropogenic transformation of territories. The results of the research indicate the need for preventive and sanitary forestry measures aiming at preservation of the diversity of stands and increasing the stability of both individual tree species and stands as a whole.

In the Kaliningrad region, the agro-industrial complex for the cultivation and processing of agricultural raw materials of animal origin, including poultry, is actively developing. One of such fast developing enterprises for growing Mulard ducks and its further processing is the ECOFARMER brand. One of the promising areas of technology development is the development and widespread implementation of technologies that provide for complex processing of raw materials in order to obtain highly profitable and high-tech food products that are as ready for consumption as possible. These products include a type of pate called rillettes, which is made from meat and fat and has meat fibers in the texture of the finished product. Studies have shown the possibility of using fatty duck trimmings with the inclusion of skin obtained after cutting the carcasses into the rillettes recipe, giving the product unique taste and texture characteristics. An important component of the developed formulation is the multifunctional additive MITPRO, which plays a key role in shaping the strength of the finished product and allows the restructuring of fat-containing components into a dense semi-finished product. The recipe composition of imitation lard has been substantiated, including 5% of the total mass of the multifunctional additive MITPRO, 30 - 40% fatty duck trimmings with the inclusion of skin, 70 - 60% of the water part. A structural and technological scheme for producing rillettes with imitation lard has been developed, its organoleptic characteristics have been studied, and it has been shown that adding it to the recipe does not reduce the score of the finished product, improving its consistency. The proposed technological solution allows for the cost-effective use of underutilized raw materials in technology, reducing food waste through their rational use.

The paper presents the results of a survey of schoolchildren aged 6–17 years to identify their preferences when choosing products for a snack, including those based on fish components. During the research, it has been found that the majority of respondents – 49.4% – resort to snacks outside the house 1–2 times a day, 27.5% – 3 or more times a day. Among the snack foods that predominate in the diet of children are chocolate and sweets (21.7%), sandwiches, hot dogs and hamburgers (21.7%), biscuits, straws and crackers (21.3%), chips and salted nuts (20.6%). These products cannot be classified as "healthy food" products. It has also been found that 55% of children do not consume fish products due to the specific taste, smell and presence of bones. However, the respondents are ready to try enriched snack products. The analysis of the survey re-sults allowed us to propose an expansion of the range of such products by improving the formulation of wheat straw by introducing washed minced fish obtained from Baltic cod (Gadus morhuas) into its composition. The paper presents the results of research to substantiate the modes of preparation of fish semi-finished products, the results of organoleptic and physicochemical parameters of enriched straws, recommendations for use determined by researchers earlier. It has been found that introduction of minced fish does not reduce the crispness of products characteristic of products with low humidity. Using rheological methods, it has been shown that the use of yeast as a leavening agent makes it possible to obtain products more airy than when using chemical leavening agents. Microbiological tests of the storage capacity of the finished product have also been carried out. The shelf life for straws with the addition of fish protein, called "Marine", is 3 months at a temperature of plus 23 ± °С with and relative humidity of not more than 65%.

The relevance of using secondary fish oil is stipulated by its high bio-logical value. Fish waste is a promising source of valuable biologically active sub-stances contained in lipids. The problem with using such oil for food and feed purposes is instability in storage as a result of hydrolytic and oxidative processes. A new direction in the use of oil-containing fish processing waste is its use as a carbon source for the microbial synthesis of products with high added value. The purpose of the work is to study the chemical composition of the quality and biological value of oil isolated by thermal method from large-scale fish processing waste of the Kaliningrad region - smoked sprat heads and fresh mackerel, pike perch entrails. The following values have been established in fish oils: acid value (7.6–12.3 mg KOH / g oil), peroxide value (5.1– 25.7 peroxide oxygen / kg oil), iodine value (129.2–148.7 g I / 100 g oil), saponification value (185.1–201.3 mg KOH / g oil), content of unsaponifiable matter (0.91–3.12%) and non-fat impurities (0.77–2.12%), anisidine value (2.8–15.4 units), thiobarbituric acid value (0.26–1.61 optical unit); mass fraction of moisture (0.28–0.81%). The com-position of fatty acids (FA) in the composition of lipids has been determined and it has been shown that the content of unsaturated acids is 66.25–73.69%; polyunsaturated 21.72–38.45%; long-chain 17.87–47.27%; long-chain polyunsaturated fatty acids of the omega 3 class (EPA 6.26–12.31% and DHA 6.67–25.02%). The results indicate a fa-vorable composition of FA lipids of the studied fats as a new carbon substrate for the biotechnological synthesis of target products.

The paper presents the results of the study of the influence of additives based on polysaccharide hydrocolloids on the degree of carotenoid loss and the organoleptic properties of molded minced meat products after steaming and deep-frying. Additives based on the following hydrocolloids have been used: sodium alginate, carrageenan, a mixture of guar and xanthan gum. It has been shown that with the addition of each of these hydrocolloids, there is a significant reduction in the degree of carotenoid loss and the total mass of the product. A positive effect of hydrocolloids on the organoleptic characteristics of finished molded products, in particular the “cut appearance”, has also been noted. When frying in oil, the smallest losses of total weight (14.0%) and carotenoids (49.1%) from the initial content have been observed when sodium alginate has been used. For the case of steaming semi-finished products, the smallest losses of total mass (9.8%), oil phase (34.2%) and carotenoids (42.0%) from the initial content are observed when using sodium alginate. The obtained data on changes in the degree of carotenoid loss correlated with changes in the type of semi-finished products in the cut. In general, a statistically significant decrease in carotenoid losses, regardless of the type of heat treatment used, has been observed in the series: no additives → gum → carrageenan → sodium alginate. Smaller losses corresponded to hydrocolloids with the highest melting point of the gels they formed. The article makes an assumption about the primary influence of mass transfer processes during heat treatment on the degree of preservation of carotenoids in the composition of molded fish products.

The paper presents the research on the use of collagen-containing additives obtained from scales (collagen-containing fibre) and skin (fish dispersions) of the common pike-perch (Sander lucioperca) in the formulation of traditional Buryat buuzy and manty. Experimental and control samples of Buryat buuzy and manty with addition of fish dispersions based on tomato and pumpkin juices, as well as collagen-containing fibre have been obtained, their organoleptic quality indicators and yield of finished products have been identified. It has been found that the joint use of collagen-containing fibre (1.2 g) and fish dispersion (26.0 g) as ingredients of the Buryat buuzy stuffing recipe allows replacing such a recipe component as beef by 18.8%, at similar organoleptic quality indicators with preservation of mass of analysed samples due to the process of gelatinisation caused by thermal treatment of collagen-containing additives contained in the stuffing, which contributes to the preservation of consumer properties and expansion of the assortment of buuzy with reduced cost price. It is shown that the addition of fish dispersion (24 g) in the composition of the recipe of minced manty allows to reduce the content of beef from 82 g to 72.4 g (a decrease of 11.7%), with similar organoleptic indicators of quality and weight of experimental samples compared with the control, which also contributes to reducing the cost of finished products. In this case, additional-ly no mechanically deboned poultry meat is used (14 g) in the control sample. Addition of fish dispersion with pumpkin juice to the dough shell of manty does not affect its taste, but contributes to the improvement of its appearance (brighter yellowish shade of color compared to the control). Thus, collagen-containing additives obtained from fish scales and skin can be recommended for the use in the formulations of various culinary dishes and semi-finished products.

It is well known that the effectiveness of lubricating oils depends on temperature. An important role in the effectiveness of lubrication is played by the sur-face tension of the oil at the interface of phase. Determination of the surface tension properties of motor oils is very desirable, since it has direct industrial significance. Although surface tension is not the most important property in determining relative lubricity, the relationship between the physical properties of used oils and surface tension has not been sufficiently studied to date. Differences in the surface tension of lubricants result in differences in their ability to maintain these thin films. It seems that in the absence of published data on the surface tension of used motor oils, the study of temperature dependences will be important for solving diagnostic problems. This article focuses on the measurement of interfacial tension and its significance when the oil is contaminated, for example, by polar organic compounds that are formed during engine operation. Interaction of oil, water and oxygen reduces oil functionality. These contaminants are attracted to the oil/air interface and, as a result, significantly reduce the interfacial tension. The temperature dependences of the density and surface tension coefficients of fresh and used marine motor oils have been measured and approximated. Correlations between these parameters have been established, which is important for the diagnostic task.

The article discusses the problem of calculating the deflection of the propeller shaft, in accordance with the requirements of the Rules of the Russian Mari-time Register of Shipping (hereinafter referred to as RMRS). Using the example of a propeller shaft of a separate vessel, a calculation diagram has been drawn up, and a calculation has been performed using the finite element method using the software (hereinafter referred to as the software) “Femap with NX Nastran”. It is shown that the calculation by the finite element method cannot be recognized as RMRS. Two main methods have been identified that can be used to obtain an approved RMRS calculation: using approved software or direct analytical methods, taking into account the requirements of the relevant regulatory documents. Software that has a standard certificate of approval by RMRS for performing such calculations has been studied, and it has been found that currently such software does not exist. A scheme is considered for calculating the deflection of the propeller shaft using the direct analytical method. Expressions are obtained for determining loads, axial moments of inertia of cross sections and bending moments at each section. It is noted that compiling an expression for bending moments and its double integration for a section with a variable cross-section that varies along its length is labor-intensive and requires the use of computer technology. A simplified calculation method (in two versions) has been proposed, which consists in replacing a section of a shaft with a variable cross-section with a section with a constant cross-section, which significantly simplifies the calculations by the direct analytical method. According to the results obtained, the corresponding replacement of the shaft section leads to some insignificant errors: no more than 0.1% in the calculations of deflections and angle of rotation, which is acceptable, according to regulatory documents. It is emphasized that the proposed assumption may have limitations in application, which will be investigated by the authors in subsequent works.