IntroductionEnvironmental pollution has been the main concernof ecologists, doctors, and food manufacturers for thelast several decades [1].Heavy metals and mercury are one of the mostwidespread and dangerous environmental pollutants.Massive mercury poisoning occurred in the 1950s-1970sas a result of the consumption of fish from mercurycontaminatedwater sources. The massive character ofthis phenomenon also triggered extensive research onthe effect of mercury on terrestrial ecosystems [2–4].Short-chain alkyl mercury compounds cause thegreatest ecotoxicological hazard. They form strongbonds with sulfur and weaker bonds with nitrogen,oxygen, and halogens. Strong mineral acids break themercury-carbon bond to form inorganic compounds.Mercury has the highest ionization potential amongother chalcophilic elements Due to this geochemicalfeature, mercury can be reduced to its atomic form andis highly resistant to oxygen and acids [5]. Mercury isscattered in the earth’s crust: its deposits have a naturalcontent of 0.02% [6–8]. In addition to the atomic state,mercury occurs in a bivalent and univalent state [9].E.B. Swain et al. claim that the air usually contains upto 5000 tons of mercury vapor or aerosol, and elementalmercury vapors can remain in the atmosphere for1–2 years [10]. Reactive ionic forms persist in theatmosphere from several hours to several days [11]. In lowpollutedair, the concentration of mercury is 0.8–1.2 ng/m3.However, near large mercury deposits it can be as high as240 ng/m3, and near gas deposits – 70 000 ng/m3, whilethe average content of mercury is 0.5–2.0 ng/m 3 [12].L. Ebinghaus et al. (1999) and E.G. Pacyna et al.(2006) proved that anthropogenic impact increasesthe man-induced component in the biogeochemicalcycle, as well as the emigration and redistribution ofnatural mercury compounds [13, 14]. In nature, mercurycompounds are highly volatile and rise in the air quiteeasily. In addition, mercury compounds are highly solublein water. Mercury is one of the most toxic elements inthe environment, with organic and inorganic mercurybeing the main forms found in food samples [15].When dissolved in water, mercury forms strongsoluble complex compounds with various organicsubstances. Methylmercury (MeHg+) results from mercuryions Hg2+ and methyl radicals CH3, which can be ofdifferent origins, including bacterial. In low salinity water,methylmercury ion HgCH3+ and hydroxymethylmercuryСН3НgОН are the most popular compounds of mercury.In natural water pools, humic and fulvic acids arethe most widespread donors of methyl groups, whilethe content of humic acids in soil is also very high.Mercury methylation depends on the ionization of theabovementioned acids, the optimal pH values for thesereactions being 6–8 [16–18].The Kemerovo Region covers an area of about95.5 thousand km2. It is a large mining, processing,chemical, and agricultural center.The Kemerovo State University conducted anexpedition to the area of t he Beloosipovo mercury deposit(Krapivinsky district). The team included scientists ofthe Institute of Biology, Ecology, and Natural Resourcesand was led by D.V. Sushchev, Candidate of BiologicalSciences. The team established the patterns of mercuryaccumulation and distribution in various components ofthe terrestrial ecosystem. They determined the mercurycontent in soil, herbaceous plants, arthropods, and smallmammals, which they harvested in various biotopesnear the mercury deposit. A small plant evaporatedмясного сырья, а также изучение степени накопления ксенобиотиков в мясе диких животных, полученных в условияхбиоценоза Белоосиповского ртутного месторождения.Объекты и методы исследования. Мышечная ткань длиннейшей мышцы спины, а также мякоть мяса лосей, добытыхружейным способом егерями в охотничьих хозяйствах Кемеровской о бласти – Кузбасса.Результаты и их обсуждение. В ходе комплексных исследований был изучен химический состав мышечной ткани и мякотимяса лося, минеральный состав мышечной ткани лося, полученной из разных анатомических частей туши животного.Биоологическую ценность мяса лося оценивали по результатам изучения аминокислотного и жирнокислотного составамышечной ткани, а также минерального и витаминного состава. Были изучены физико-химические показатели мясалося, характеризующие его жесткость, потери при тепловой обработке, способность связывать и удерживать влагу, чтообеспечивает его сочность. Завершающий этап исследований связан с изучением накопления ксенобиотиков в опытныхобразцах нетрадиционного мясного сырья, полученного вблизи райо на Белоосиповского ртутного месторождения.Выводы. Убойный выход составил 51–53%, что превышает выход мяса крупного рогатого скота на 4–6%. По химическомусоставу содержание влаги в мясе лося составило 73–78%, белка 20–24%, в зависимости от анатомического расположениямышц, жира 0,75–1,75%. Динамика накопления изменения ртути в мясе лося при разных температурных режимах егохранения составляла в пределах от 0,004 ± 0,001 до 0,009 ± 0,00 1 мг/ кг (при ПДК 0,03 мг/кг).Ключевые слова. Лось, ртуть, биоценоз, мясо, химический состав, функционально-технологические свойства, выдержкаДля цитирования: Просеков А. Ю., Альтшуллер О. Г., Курбанова М. Г. Исследование качества и безопасности мясадиких животных, полученного в условиях биоценоза Белоосиповского ртутного месторождения // Техника и технологияпищевых производств. 2021. Т. 51. № 4. С. 654–663. (На англ.). https://doi.org/10.21603/2074-9414-2021-4-654-663.656Prosekov A.Yu. et al. Food Processing: Techniques and Technology, 2021, vol. 51, no. 4, pp. 654–663mercury from ore in the Belaya Osipova river valleyin 1969–1975 (https://www.krapivino.ru/node/15303).Based on the e-catalog of geological documents(Russian Federal Geological Fund), specialists from theKemerovo State University referred the Beloosipovomercury deposit to the Kuznetsk fault zone. Themineralization here is uneven and scattered. The mercurydeposit is estimated as 124 tons, cinnabar (HgS) being themain ore-bearing mineral. The deposit has a hydrothermallow-temperature origin and is located in the zone ofdeep and echelon faults. Mercury manifests itself hereas occasional ore occurrences, points of mineralization,concentrate and geochemical aureoles, etc. Areas ofhigh mercury concentration intersperse with barrenones. The area featured in the present research is partof the Pezas-Beloosipovo mercury ore zone and theBeloosipovo mercury ore deposit [19].The highest concentration of mercury is 1.5 kmnorth of the mine: soil – 0.72 and 0.96 mg/kg, plants –0.064 mg/kg, insects – 0.063 mg/kg, rodents – 0.091 mg/kg,insectivores – 0.056 mg/kg. The maximum allowableconcentration (MAC) of mercury in soil is 2.1 mg/kg.Therefore, the mercury concentration in the local soilwas well within the norm (0.72 and 0.96 mg/kg).Soil plays an important role in the globalbiogeochemical cycle of mercury. As it settles on thesoil surface, its further route into aquatic ecosystemslargely depends on terrestrial ecosystems [20, 21]. Inaddition to elemental mercury, soil contains inorganicand organic compounds [22]. Inorganic compoundsexist in mobile (water- and acid-soluble), oxide, andsulfide forms.Mercury concentration is known to be much lowerin the soils of national parks with their minimal externalanthropogenic impact than in the areas affected by humaneconomic activities.All forms of mercury in soils can be divided intofour types:1) water-soluble mercury is described as readily availableto plants;2) mercury soluble in an acetate-ammonium buffersolution (pH 4.8) is believed to be conditionally easilyavailable to plants;3) acid-soluble mercury is classified as potentiallyavailable to plants;4) alkali-soluble forms of mercury are conditionallyassociated with mobile humic substances.The content of mercury in one and the same typeof soil can be different as it depends on the adjacentlandscapes. For instance, its concentration is lower inseparate eluvium than in conjugated transeluvial andsuper-aquatic soils, which is associated with migrationaccumulativeprocesses.In continental biogeocenoses, mercury concentrationincreases in the following order: plants > insects > soilmicroorganisms > herbivorous mammals > carnivorousmammals > macromycetes [23].In 2018–2021, water samples from the BelayaOsipova exceeded the MAC for mercury by 5–20%.Probably, the groundwater and surface floods are leachingmercury compounds from the deposit. However, thebiological diversity proves that such concentrationshave no pronounced impact on the local ecosystem.In fact, the concentration of mercury goes down as itmoves up the food chains.The Beloosipovo mercury deposit is surrounded bytaiga with its typical flora and fauna, including gameanimals and birds. Professor A.Yu. Prosekov alsocommented on the diversity of Beloosipovo flora in hisarticle Migration of Mercury in the Food Chains of theBeloosipovo Biocenosis. The local taiga is predominatedby Siberian spruce (Abies sibirica Ledeb.), aspen (Populustremula L.), birch (Betula pubescens Ehrh., Betulapendula Roth), and lush herbaceous vegetation up tothree meters tall. The rich undergrowth is formed by suchshrubs as goat willow (Salix caprea L.), cranberry bush(Viburnum opulus L.), pea shrub (Caragana arborescensLam.), Siberian mountain ash (Sorbus sibirica Hedl.),and bird cherry (Padus avium Mill.). Some undergrowthareas are represented by sparse shrubbery, which isknown to attract wild animals, such as elk.The list of herbaceous plants includes melancholythistle (Cirsium heterophyllum (L.) Hill.), millet grass(Milium effusum L.), dissected hogweed (Heracleumdissectum Ledeb.), wild chervil (Anthriscus sylvestris (L.),cacalia (Cacalia hastata L.), Siberian hawk’s beard(Crepis sibirica L.), northern wolfsbane (Aconitumseptentrionale Koelle), meadowsweet (Filipendulaulmaria (L.) Maxim.), Siberian globeflower (TrolliusFigure 1. Elk population in the Krapivino district4654974984911772015 2016 2017 2018 2019657Просеков А. Ю. [и др.] Техника и технология пищевых производств. 2021. Т. 51. № 4 С. 654–663asiaticus L.), and giant fescue (Festuca gigantea (L.)Vill.). All these plants serve as food base for taiga fauna.Forest phytocenoses prevail in the research area, e.g.aspen-birch-fir forest with lush tall grass and occasionalSiberian spruces. The growing anthropogenic load makesit necessary to study the patterns of its effect on thelocal wild animal population. Professor A.Yu. Prosekovdescribed the changes in the elk population in his researchEffect of Forest Coverage on Elk Population in Kuzbass.Fig. 1 illustrates the pattern of elk population in theKrapivino district in 2015–2019 as reported by theDepartment of Wildlife Protection of the KemerovoRegion (Fig. 1) [24–26].In 2017, the elk population reached its peak, whilethe total rise for 2015–2019 was 163%. The area ofthe hunting grounds in the Krapivino district is 8328hectares, i.e. 805 hectares of forest per animal, whichprovides a fairly good forage base [25–27].Elks (Alces a. Pfizenmayeri Zukowski) avoid denseforests. They prefer sparse forests and overgrownclearings, glades, and meadows that are rich in forage.The vast burnt-out areas with young plants are home to alarge elk population. Elks spend all seasons in mixed anddeciduous forests. In summer, they eat leaves, reachingas far as their considerable height allows them. Theyfeed on tall grasses in burnt-out areas and logging spots.Late in summer, they eat all kinds of mushrooms, evenfly agarics – for medicinal purposes. In September,elks start eating shoots and twigs, and by Novemberthey almost completely switch to browse forage. Theirdaily food intake varies from season to season. An adultelk consumes 35 kg of food per day in summer and12–15 kg in winter, i.e. about seven tons of plant foodper year. If elk population increases, they can damageforest nurseries and plantings. Elks use every opportunityto lick salt, sometimes even the salt mix that is used tomelt snow on highways [28, 29].The elk is a game animal, which makes its meat anobject of research interest. Its quality and safety dependson the fact whether it accumulates such xenobiotics asmercury. Experimental studies and chance finds provethat 0.1–200 mg of mercury per 1 kg of wet weightcan destroy the normal reproduction pattern and lifeof warm-blooded animals, depending on numerousfactors [30].Xenobiotic contamination of food raw materialsand products usually corresponds with the degree ofenvironmental pollution. Moving along the food chain,contaminants enter human body and cause serious healthproblems. Food chains are one of the main routesthat harmful chemicals take to get into human body.Science knows more than nine million xenobiotics ofvarious nature. According to the Food and AgricultureOrganization (FAO) and the World Health Organization(WHO), people consume 80–95% of contaminants withfood and 4–7% with drinking water, while 1–2% entershuman body from the air through the skin.The research objective was to study the chemicalcomposition, functional, technological, and physicochemicalproperties, and the accumulation ofxenobiotics in the raw elk meat obtained from thebiocenosis of the Beloosipovo mercury deposit.The goal was to define:– the anatomical and chemical composition of elk meatfrom the forests of the Krapivino region in the vicinityof the Beloosipovo mercury deposit;– the amino acid, fatty acid, and mineral compositionof elk meat, as well as its functional and technologicalproperties;– the degree of accumulation of mercury in meat samplesin their native state during storage and after variousmethods of processing.Study objects and methodsThe research featured muscle tissue from the ribeye area and fat and muscle tissue from the hind legsof three elks (two males, one female) shot by the gamewardens in the hunting farms of the Kemerovo Region.The sample description included the sex, body carcassweight, and approximate age of the animals. The selectedsamples were placed in a chemically neutral package,sealed, and stored at –20 ± 2°C. The sampling procedureand freshness test followed State Standard 7269-2015.Moisture content was determined according to StateStandard 33319-2015; fat – by a Soxhlet extraction deviceaccording to State Standard 23042-2015; total protein –by the Kjeldahl method according to State Standard25011-2017. All the biochemical studies involved modernanalytical equipment from the laboratory of the ResearchInstitute of Biotechnology, Kemerovo State University.The list of indicators to be defined included the contentof fatty acids, vitamins, and macro- and microelements.The mineral composition of the elk meat was determinedusing an X-ray fluorescence spectrometer (Carl ZeissJena). The amino acid composition was tested with anautomatic amino acid analyzer Aracus PMA GmbH, whichwas approved by directives 98/64/EU and 2000/45/EU.The method presupposed a cation-exchange separationof amino acids with a stepwise pH gradient and a postcolumnderivatization with ninhydrin. The fatty acidcomposition was determined by gas chromatographybased on State Standard 55483-2013.Hydrogen ions (pH) were studied by the potentiometricmethod, the moisture-binding and moisture-retainingcapacity – by centrifugation and pressing. To definethe mercury concentration, the muscle tissue sampleswere dried and subjected to dry ashing by the coldvapor method in a Julia 5K device.Results and discussionThree elks were shot in the Krapivinsky district duringthe hunting period (October – November) of 2017–2020to assess the possible xenobiotic contamination of meat.Sample 1 weighed 270.0 ± 10.5 kg, sample 2 – 310.0 ±658Prosekov A.Yu. et al. Food Processing: Techniques and Technology, 2021, vol. 51, no. 4, pp. 654–66313.5 kg, and sample 3 – 260.0 ± 10.0 kg. The carcassesweighed 143.40 ± 7.15 kg, 165.20 ± 8.26 kg, and 137.80 ±6.89 kg, respectively. The slaughter yield was within51–53%, which exceeded the meat yield from farmcattle (47–50%).The elk is the largest representative of deer. Theelk meat samples were dark red, with coarse fiber andalmost no fat in the muscle tissue. Scarce fat stripeswere observed on the neck and chest. The highest fatcontent was registered in the pelvic cavity and the lumbararea. The fat was white and hard and crumbled at roomtemperature. The melting point of fat from differentparts of the carcass ranged from 47.1 to 48.5°C.The lymph nodes were oval and varied in size. Theywere gray-white on the surface, while their peripheralareas were darker, which suggests that the animals werehealthy.The initial sensory analysis included boiling thesamples in order to assess the quality of the broth.The broth was transparent and had a typical meatysmell, which indicated the good quality of the meat.The freshness test procedure for game meat includeda complex of studies, which consisted of a sensoryevaluation, bacterioscopy of deep layers, cooking test andammonia reaction with Nessler’s reagent. The complexanalysis confirmed the freshness of the meat samples.Table 1 shows the anatomical and chemicalcomposition of the elk meat.The average morphological composition of elkcarcasses was as follows (% of the carcass weight).Muscle tissue predominated, the yield being 73 ± 2%; thecontent of bones and cartilage was 18 ± 2%, connectivetissue – 8 ± 1%, and fat – 0.7 ± 1%. Table 1 shows thatthe moisture content in the rib eye sample was 78.14 ±3.90 g/100 g, which exceeded this indicator in the averageflesh sample by 5.91%. The samples demonstrated ahigh protein content of 23.62%, which exceeded thatof farm animal meat, e.g. in pork and beef, the massfraction of protein is 14–15 and 16–17%, respectively.The protein:fat ratio was 1:0.07, while for farm cattlethis ratio is 1:0.5. Unlike more traditional raw meat,elk meat has low fat content, which proves its dietaryproperties and a lower chol esterol profile.Table 1. Morphological and chemical composition of elk meat (n = 3)Indicator № 1 № 2 № 3 Mean valueAnatomical composition, kgMuscle tissue 105.39 ± 5.15 121.42 ± 6.08 101.28± 5.67 109.36 ± 5.46Fat 0.86 ± 0.11 1.16 ± 0.09 0.84 ± 0.13 0.95 ± 0.11Connective tissue 11.23 ± 1.75 13.05 ± 0.96 10.88± 1.18 11.72 ± 0.58Bones and cartilage 25.81± 1.99 29.81 ± 1.69 24.82 ± 1.16 26.81 ± 1.60Chemical composition of rib eye sample, g/100 gMoisture 77.85 ± 3.11 78.88 ± 2.94 77.61 ± 3.18 78.14 ± 3.90Total protein 19.88 ± 0.79 21.56 ± 0.86 19.75 ± 0.78 20.39 ± 0.81Fat 0.77 ± 0.03 0.82 ± 0.03 0.68 ± 0.02 0.75 ± 0.03Ash 0.99 ± 0.04 1.23 ± 0.04 1.05 ± 0.04 1.09 ± 0.04Chemical composition of the average sample of flesh, g/100 gMoisture 72.62 ± 2.27 74.14 ± 2.13 73.82 ± 2.04 73.52 ± 3.65Total protein 23.32 ± 0.85 24.65 ± 1.05 22.91 ± 0.88 23.62 ± 1.18Fat 1.70 ± 0.06 1.73 ± 0.07 1.80 ± 0.07 1.74 ± 0.08Ash 1.21 ± 0.05 1.42 ± 0.04 1.34 ± 0.06 1.32 ± 0.06Other substances 1.31 ± 0.05 1.48 ± 0.05 1.30 ± 0.04 1.36 ± 0.04Table 2. Amino acid composition of elk meat (rib eye), g/100 g of protein (n = 3)Amino acid Content Amino acid ContentEssential NonessentialValine 2.55 ± 0.06 Methionine + Cysteine 2.87 ± 0.08Isoleucine 3.83 ± 0.11 Hydroxyproline 0.55 ± 0.01Leucine 3.58 ± 0.10 Glutamine 3.86 ± 0.11Lysine 4.86 ± 0.24 Proline 0.98 ± 0.02Methionine 1.75 ± 0.04 Serine 2.62 ± 0.07Tryptophan 3.96 ± 0.02 Glycine 2.82 ± 0.08Threonine 3.64 ± 0.10 Alanin 2.77 ± 0.08Phenylalanine 1.73 ± 0.05 Arginine 3.66 ± 0.11Total 25.90 ± 0.68 Total 20.13 ± 0.58659Просеков А. Ю. [и др.] Техника и технология пищевых производств. 2021. Т. 51. № 4 С. 654–663The biological value of meat depends on the mainnutrients, in particular, amino and fatty acids. Therefore,the next task was to determine these indicators for therib eye samples (Table 2–3, Fig. 2).The total amount of essential amino acids in theelk rib eye samples exceeded the nonessential ones by23%. The total amino acid level was 46.03 ± 1.38 gper 100 g of protein.The list of the most abundant essential amino acidsstarted with lysine (4.86 ± 0.24), tryptophan (3.96 ±0.02), and isoleucine (3.83 ± 0.11). The nonessentialamino acids were dominated by glutamine 3.86 ± 0.11and arginine 3.66 ± 0.11 g/100 g of protein.The ratio of the essential and nonessential amino acidswas high in the rib eye samples: the protein quality index(PQI) was 7.2, with a rather high content of tryptophanand a low content of hydroxyproline. For beef, thePQI is 5.0–5.5.Oleic acid proved to be the most abundant unsaturatedfatty acid. It improves human metabolism and immunesystem; it is good against cholesterol and insulinresistance. Oleic acid occupied 85% of the total amountof unsaturated fatty acids. Palmitic acid topped the listof saturated fatty acids. The total amount of saturatedfatty acids in the rib eye sample was 33.32 ± 0.98%,that of unsaturated – 51.83 ± 1.55%.Minerals also increase the nutritional and biologicalvalue of meat. They are important for metabolism,growth, and development. Table 4 shows the mineralcomposition of the elk meat.12.844' Asp16.523' Ser17.642' Thr19.738' Glu21.724'25.083' Pro27.768' Gly28.716' Ala31.653' Cys33.276' Met34.810' Ile35.691' Leu37.753' Tyr41.203' Phe44.166' His45.028'46.404'52.462' Lys54.591' NH460.962' Arg080160240320400480560640720800mV15 20 25 30 35 40 45 50 55 60 min1 – tryptophan, 2 – threonine, 3 – isoleucine, 4 – hydroxyproli ne, 5 – serine, 6 – glycine, 7 – alanine, 8 – valine, 9 – methi onine,10 – cystine, 11 – leucine, 12 – glutamine, 13 – proline, 14 – phenylalanine, 15 – lysine, 16 – arginine, 17 – methionine + cy steineFigure 2. Chromatographic profile of the amino acid composition of elk rib eyeTable 3. Fatty acid composition of elk rib eye, % (n = 3)Acid Content Acid ContentSaturated fatty acids Unsaturated fatty acidsLauric 1.09 ± 0.03 Palmitooleic 6.54 ± 0.19Myristic 0.75 ± 0.02 Oleic 44.02 ± 1.32Palmitic 26.13 ± 0.74 Linoleic 1.10 ± 0.03Stearic 5.26 ± 0.15 Linolenic 0.17 ± 0.01Arachinic 0.09 ± 0.01 Total 51.83 ± 1.55Total 33.32 ± 0.98660Prosekov A.Yu. et al. Food Processing: Techniques and Technology, 2021, vol. 51, no. 4, pp. 654–663The samples proved to be rich in potassium (306.33 ±6.12 mg/100 g), sulfur (196.42 ± 3.95 mg/100 g), andphosphorus (195.02 ± 3.85 mg/100 g). Unlike beef andpork, elk meat appeared to contain a lot of potassium,sodium, magnesium, iron, and phosphorus. For example,elk meat has more potassium than pork and beef by 7and 10%, sodium – by 24 and 35%, and iron – by 17 and30%, respectively. Iron with its 2.90 ± 0.08 mg/100 gwas the predominant trace element.The quality of the muscle tissue was tested accordingto its physicochemical parameters, cooking losses,and moisture-retaining properties, i.e. the propertiesthat defined the juiciness of the meat. Another testmeasured the pH value, which depended on biochemicalchanges related to maturation processes and glycogenconversion (Table 5).The analysis of the functional and technologicalproperties involved moisture-binding capacity (73.36 ±3.50%) and water-retaining capacity (59.57 ± 1.78%).The hydrogen index (pH) of meat varied from 5.8 to6.2 units, which means that a small amount of lactic acidprevented the development of putrefactive microflora.The water-retaining capacity depends on the abilityof proteins to bind water in various ways, both on thesurface and inside. Therefore, it is responsible forjuiciness, tenderness, market quality, cooking and freezinglosses, etc.The elk meat samples appeared to be quite tender:the shearing strength was 2.36 ± 0.07 kg/cm 2, and thecooking losses were only 20.19 ± 1.20%. The size ofthe rib eye characterizes the fleshing of carcass; thisindicator was 31.67 ± 0.95 cm2, which meant a relativelyhigh meat production.The final stage of the research featured theaccumulation of xenobiotics, in particular, mercury.The high toxicity of mercury depends on the typeof compound. Various mercury compounds differ inthe way they are absorbed, get involved into metabolicTable 4. Mineral profile of elk meat, mg/100 g (n = 3)Micronutrients № 1 № 2 № 3 Mean valueIron 2.91 ± 0.09 2.88 ± 0.08 2.93 ± 0.08 2.90 ± 0.08Copper 5.48 ± 0.16 6.21 ± 0.18 6.33 ± 0.18 6.01 ± 0.18Calcium 10.22 ± 0.30 10.31 ± 0.30 11.01 ± 0.35 10.51 ± 0.33Magnesium 24.55 ± 0.49 24.41 ± 0.47 23.88 ± 0.45 24.28 ± 0.47Sodium 77.41 ± 1.54 76.88 ± 1.53 77.32 ± 1.54 77.20 ± 1.54Zink 125.66 ± 2.51 133.45 ± 2.66 129.75 ± 2.19 129.62 ± 2.28Phosphor 194.43 ± 3.88 194.41 ± 3.88 196.22 ± 3.81 195.02 ± 3.85Sulfur 195.54 ± 3.91 197.21 ± 3.94 196.51 ± 3.93 196.42 ± 3.95Potassium 305.22 ± 6.10 307.33 ± 6.14 306.44 ± 6.11 306.33 ± 6.12Table 5. Physicochemical, functional, and technological properties of elk muscle tissue (n = 3)Indicator № 1 № 2 № 3 Mean valueрН 5.80 ± 0.12 6.00 ± 0.14 6.2 ± 0.16 6.00 ± 0.14Color intensity, Е×1,000 375.80 ± 11.10 376.91 ± 10.2 375.00 ± 10.5 375.90 ± 10.47Moisture-binding capacity, % 74.66 ± 2.23 72.33 ± 2.16 73.11 ± 2.19 73.36 ± 3.50Moisture-retaining capacity, % 58.62 ± 1.75 59.88 ± 1.79 60.21 ± 1.80 59.57 ± 1.78Cooking loss, % 20.58 ± 1.21 18.99 ± 1.16 21.01 ± 1.23 20.19 ± 1.20Rib eye area, cm2 (at ribs 12–13) 31.21 ± 0.93 32.01 ± 0.96 31.80 ± 0.95 31.67 ± 0.95Shearing strength, kg/cm2 2.10 ± 0.06 2.59 ± 0.07 2.40 ± 0.07 2.36 ± 0.07Table 6. Accumulation of mercury in elk muscle tissue during maturation (n = 3)Exposure time Mercury concentration, mg/kg of solids Mean value№ 1 № 2 № 3At 20 ± 2°СControl (fresh meat) 0.004 ± 0.001 0.003 ± 0.002 0.005 ± 0.001 0.004 ± 0.0012 days 0.006 ± 0.002 0.005 ± 0.001 0.007 ± 0.001 0.006 ± 0.001At –20 ± 2°С5 days 0.005 ± 0.001 0.004 ± 0.001 0.007 ± 0.001 0.005 ± 0.00110 days 0.007 ± 0.001 0.006 ± 0.001 0.009 ± 0.001 0.007 ± 0.00115 days 0.009 ± 0.001 0.008 ± 0.001 0.012 ± 0.001 0.009 ± 0.001661Просеков А. Ю. [и др.] Техника и технология пищевых производств. 2021. Т. 51. № 4 С. 654–663processes, and excreted from the body. Mercury is toxicbecause it interacts with sulfhydryl proteins. By blockingthem, mercury changes their properties or inactivates anumber of vital enzymes. As it enters the cell, mercuryincorporates into the DNA, which can cause hereditarydisorders [31].The brain exhibits a special affinity for methylmercury:its ability to accumulate mercury is almost six timeshigher than that of other organs. Inorganic mercurycompounds disrupt the metabolism of ascorbic acid,calcium, copper, zinc, and selenium. Organic mercurycompounds affect the metabolism of proteins, cysteine,ascorbic acid, tocopherols, iron, copper, manganese, andselenium. It takes mercury compounds 70 days to leavehuman body. Zinc and especially selenium can protecthuman organism from mercury compounds. Seleniumforms a non-toxic selenomercury complex as a resultof demethylation of mercury. Ascorbic acid and coppercan lower the toxicity of inorganic mercury compounds,while proteins, cysteine, and tocopherols help againstorganic mercury compounds. The acceptable weeklyintake of mercury cannot exceed 0.3 mg. The acceptabledaily intake of mercury is 0.0006 mg per 1 kg of bodyweight [31, 32].The UN, WHO, and FAO developed the basicindicators of food hygiene based on toxicological criteria:MAC is the maximum allowable concentration ofcontaminants in the air, water, and food from the pointof view of safety for human health. Daily exposureto MAC for an arbitrarily long time does not triggerdiseases or health problems that can be detected bymodern research methods in the life of the present andsubsequent generations.ADI is acceptable daily intake that does not affecthuman health throughout life (mg/kg).TDI is the tolerable daily intake calculated as ADImultiplied by the average body weight (60–70 kg) thata person can consume daily throughout life withoutrisk to health [33].The content of mercury in elk muscle samples wasdetermined in fresh meat samples (control), after twodays of storage at 20 ± 2 °C, and on storage days 5,10, and 15 at –20 ± 2 °C (Table 6).Mercury concentration in the muscle tissue increasedwith maturation, even at low temperatures. On storageday 15 at –20 ± 2 °С, it increased by approximately2.25–2.6 times. At room temperature, the rate of mercuryconcentration in the muscle tissue doubled.However, mercury concentrations at differenttemperatures did not exceed the MAC value of0.03 mg/kg.On storage day 15 at low temperatures, severalsamples were thawed and subjected to frying and boilingto determine the mercury content. Boiling decreased themercury concentration by 22%. However, boiling doesnot affect the concentration of xenobiotics in mushrooms.In mushrooms, mercury is bound with amino groupsof nitrogen-containing compounds, and in meat – withsulfur-containing amino acids. Frying decreased themercury concentration by 25%: this value could beimproved by subjecting the meat to preliminary grinding.ConclusionThe present research revealed some useful data onthe composition and properties of raw elk meat, such asmercury concentration and its patterns during storage.The slaughter yield was 51–53%, which issignificantly higher than for farm cattle (45–47%). Theanatomical composition of elk carcass was as follows:muscle tissue – 73 ± 2%, bones and cartilage – 18 ± 2%,connective tissue – 8 ± 1%, fat tissue – 0.7 ± 1%.The moisture content in the rib eye muscle tissue was78.14 ± 3.90 g/100 g, which exceeded the average fleshsample by 5.91%. The elk meat proved to have a highprotein content of 20–24%, while the protein:fat ratioin the flesh sample was 1:0.07, which classifies the elkmeat as a dietary product.The total level of amino acids was 46.03 ± 1.38 g/100 gof protein, while the total amount of essential amino acidsin the rib eye tissue exceeded that of nonessential acidsby 23%. The total amount of saturated fatty acids in therib eye sample was 33.32 ± 0.98%, that of unsaturatedfatty acids – 51.83 ± 1.55%.The mineral composition of elk meat was dominatedby potassium (306.33 ± 6.12 mg/100 g), sulfur (196.42 ±3.95 mg/100 g), and phosphorus (195.02 ± 3.85 mg/100 g).The water-binding capacity was 73.36 ± 3.50%,while the water-retaining capacity was 59.57 ± 1.78%.The pH of the elk meat varied from 5.8 to 6.2 units; theshearing strength was 2.36 ± 0.07 kg/cm2. The cookinglosses were as low as 20.19 ± 1.20%.The final set of experiments measured the level ofxenobiotics in the elk meat obtained from the biocenosisof the Beloosipovo mercury deposit. The mercury contentdid not exceed the maximum allowable concentrationof 0.03 mg/kg at different temperature conditions. Atroom temperature storage, the change in the mercurycontent in muscle tissue was twice as fast as in the frozensamples. Heat treatment decreased the concentrationof mercury by 22–25%.ContributionAll the authors contributed equally to the study andbear equal responsibility for information published inthis article.Conflict of interestThe authors declare that there is no conflict of interestregarding the publication of this article.