Introduction Bakery and flour confectionery products are an in-tegral part of daily nutrition for the majority of the population. Snacks occupy an increasing place in the structure of modern person's nutrition, which are pri-marily resorted to by the most mobile segments of the population: schoolchildren, students, office employees and others. Their diet, as a rule, does not correspond to the physiological needs of the body. The Ministry of Health of Russia notes insufficient intake of animal protein, deficiency of vitamins and minerals, predomi-nance of carbohydrate-fat component and animal fats, excess of simple carbohydrates [1]. Our survey of teenagers aged 15-16 showed that most of them eat 3 meals a day (45%), although there are also those who are limited to 1-2 meals a day (32%) [2]. The main snack of the interviewed children are fruits, pizza, sandwiches, buns and sweets (Fig. 1). Fig. 1. Types of snacks for teenagers aged 15-16 Fig. 1 shows that 22% are bakery and flour con-fectionery products (BaFCP), which, in addition to school, are also consumed in sufficient quantities at home. Therefore, it is important to increase the bio-logical value of these products as the most popular among young people. Bakery and flour confectionery products are predominantly carbohydrate products, so it is advisable to enrich them with protein, minerals, and vitamins. Recently, as the main sources of protein in the en-richment of BaFCP scientists suggest using supple-ments of plant origin (oilseed meal, concentrates and protein isolates of soybean seeds, sunflower, cotton, peanuts, sesame, beans, canola, potato products) and animal origin (milt of salmon fish species, surimi, kefir starter, whey of milk) [3]. Fish protein is of particular interest as a complete protein. Our analysis of teenagers' diets showed that fish, unfortunately, is popular with only 17% [2]. Research works of the Russian scientists A. P. Chernogortsev, R. G. Razumovskaya, A. S. Lysova, I. A. Bes-smertnaya on use of washed or fermented fish mince in technology of flour confectionery [3-9], M. E. Tsi-bizova's, N. D. Averjanova's on the influence of milk whey on intensity of partial disaggregation of protein of fish muscle tissue [10] are well known. However, in the production of BaFCP, the method of introducing fish protein-mineral mass into the whey-based dough has not been previously used.The purpose of this work is to improve the tech-nology of BaFCP by enriching them with fish protein, protein-mineral additive (PMA) based on fish and dairy raw materials.Objects and research methodsThe main object of the study was Baltic cod (Gadus morhua), corresponding to GOST 814-2019 “Chilled fish. Technical conditions”. In addition, there was used whey (GOST 34352-2017 “Milk whey - raw materials. Technical conditions”), high-grade wheat flour (GOST 26574-2017 “Baking wheat flour”), whole-grain rye flour (GOST 7045-2017 “Baking rye flour”). In terms of safety, the raw materials met the requirements of TR EAEU 040/2016, TR CU 033/2013, TR CU 021/2011.In the research there were used standard and generally accepted organoleptic, physico-chemical, biochemical and microbiological methods. Organoleptic evaluation of the finished products included score and profile methods. The amino-acid, fatty-acid and mineral compositions of the rye-wheat bread were determined by the optical method by using a spectral analyzer “NIRS DS2500F” (laboratory of the Veterinary Research Center, Kaliningrad region).Modeling and optimization of the formulation of enriched wheat galettes, rye-wheat breads were carried out by experimental planning method by using orthog-onal central composite plan of the second order for two factors.Statistical processing of the data was performed using conventional methods at a confidence probability of 0.95. The main experiments were conducted in threefold repeatability. Microsoft Word 2010 and Microsoft Excel 2010 were used to process the results.Research results and discussionAt the initial stage of the work there was investi-gated the possibility of protein enrichment of fish flour confectionery products (FCP). Wheat biscuits were chosen as an object for upgrading the formulation. The latter are FCP of layered structure with mass fraction of moisture not exceeding 11%, sugar (sucrose in terms of dry matter) – not less than 11%. Products can be considered as snack products. In determining the taste preferences of the most common recipes for biscuits by baking trials and or-ganoleptic evaluation allowed to choose the recipe “Simple”, which includes wheat flour, water, leavening agent, salt, sugar, sunflower oil and starch. The latter is used to improve the rheological properties of the dough, organoleptic characteristics and the persistence of FCP.Analysis of literature data showed that fermentoly-sis of minced fish leads to decomposition of proteins of the fish muscle tissue into the large-molecule com-pounds: albumin, peptones, peptides [4, 5]. Fermen-tolysis contributes to the acquisition of fish protein mass of the properties necessary for its use as a filler of food products in order to increase their biological value. After fermentolysis a PMA can be obtained with rheological properties that contribute to a better combination with the dough prepared on the basis of wheat flour at baking. The PMA obtained in this way and introduced into the dough provide good viscosity, stickiness and appropriate hydrophilic properties.To improve the recipe of biscuits it was proposed to introduce in the dough the fermented minced fish obtained in the following way. The Baltic cod muscle tissue was ground on a cutter and sent for fermentoly-sis, which was carried out in the presence of water at the minced fish: water as 1 : 1, temperature 22 ± 2°С and duration of 20 minutes. Then the water was re-moved and injected into the dough.To establish the optimal parameters of the process of preparation of wheat biscuits of high biological value the experiment was mathematical planned. There was used the amount of introduced starch (xs) and fermented fish mince (xm) as varying particular factors subject to regulating and optimizing. A dimensionless generalized indicator that combines two partial responses: porosity and adhesion was selected as a parameter of optimizing the mathematical model y to improve the objectivity of the results of the study. Processing of the obtained data allowed to calculate the parameters of the equation adequately linking the generalized optimization parameter with the variable factors, which helps predict the quality of the product: Calculation of optimum values of factors, namely starch content (xs) – 5.5 g/100 g product, minced fish (xm) – 18 g/100 g product, allowed to develop a recipe for wheat biscuits “Kaliningrad” enriched with fish protein (Fig. 2). Fig. 2. Wheat biscuits “Kaliningrad” enriched with fish protein Organoleptic evaluation of enriched biscuits showed that they are rectangular-shaped FCP, with a smooth surface without bloat and cracks, with a uniform color from straw-yellow to light brown, the appearance in the break – layered, baked, with uniform porosity, without bloat, hardening and traces of unmixed, taste and smell - pleasant, typical of this type of products, fish tones are almost not expressed. Phys-ico-chemical indices are presented in Table 1, where we can see that protein content in enriched biscuits increased by 47.5%, mineral substances – by 38.8 %. Table 1Physico-chemical indicators of the quality of biscuitsIndicator nameBiscuits “Simple” (control sample)Biscuits “Kaliningrad” (experimental sample)Mass fraction of moisture, %9.5510.05Mass fraction of protein, %10.1514.97Mass fraction of fat, %1.801.60Mass fraction of carbohydrates, %*77.2471.95Mass fraction of minerals, %1.261.43Alkalinity, deg.0.60.6*Data were obtained by calculation. The results obtained show the promise of the work and require further research.Another area of research carried out at the Depart-ment of Food Biotechnology of Kaliningrad State Technical University is to improve the technology of bakery products – rye-wheat bread [11]. Introducing the fish protein additive into the dough allowed obtaining a product with attractive organoleptic properties. Studying the chemical composition showed an increase in protein, but not any significant increase in minerals. That is why it was suggested to use not only fish muscular tissue but also its supporting-framework and covering tissues. The latter are a source of calcium, phosphorus, collagen protein, which are the building blocks for the growing body of a teenager strengthening his musculoskeletal system. Table 2 presents the results of studies of the chemical composition of the carcass of Baltic cod (Gadus morhua). Table 2General chemical composition of the carcass of Baltic cod (Gadus morhua)Type of fishMass fraction, %Energy value, кDg/100 gWaterProteinFatMineral substancesBaltic cod, carcass78.6514.152.754.4581.43 It can be seen that the minced meat of the Baltic cod carcass by the mass fraction of protein is at the level of the most used marine fish species. In terms of protein content, cod is included in the group of protein fish (15-20%), and in terms of fat content – to dietary (low-fat) (0.1-4%), which indicates its high biological value and the prospect of use in bakery technology.A high calcium content has been experimentally proven (Table 3) in the carcass of cod, due to its high content in the bones of fish, including vertebrates. Table 3Content of calcium and phosphorus in the carcass of Baltic cod (Gadus morhua)Type of fishCalcium, mg/kgPhosphorus, mg/kgBaltic cod, carcass1 555.2860The Ca : P ratio is 1 : 0.6, which is potentially bene-ficial for the human body.Acid-enzymatic hydrolysis in milk serum (whey) was used to soften fish tissues. The latter is character-ized by the low caloric value and high biological value: it contains milk protein, B vitamins, as well as a complex of such mineral compounds as potassium, sodium, calcium, magnesium, iron and others.To optimize the process of fish raw material disag-gregation the cod carcass was passed through the spin-ner from 1 to 3 times. Disaggregation time varied from 2 to 4 hours. Hydromodule of the ratio “fish mince: milk whey” was 1 : 1 at temperature 20-22°С. pH of the initial fish-milk mixture was 5.8-6.0, that was close to optimal value of work of cathepsins of fish raw muscle tissue, milk-acid microflora and chymosin – rennet enzyme remaining in whey after cheese making. Implementation of the experimental plan and processing of the obtained data allowed to calculate the equation adequately linking the generalized optimization parameter with the factors being changed, which allows for maximum degradation of protein-mineral mass while maintaining attractive organoleptic indicators. Fig. 3 shows a geometric model of the optimization process of fish raw material disaggregation in milk whey. Fig. 3. Geometric model of optimizing the disaggregation of fish raw materials in dairy whey Optimal parameters were: 2.05 times – degree of crushing of fish raw material, we take accordingly 2 times, 3.92 h – duration of disaggregation, we take 4 h. The resulting protein-mineral mass was tested in the manufacture of rye-wheat bread, which was intro-duced directly when kneading dough. The baked finished product was a bakery product of regular shape, without indentations, with even edges, surface smooth, without swellings and cracks, color – uniform from light gray to light brown, crumb condition – well baked, with a uniform structure, without signs of unmixed, taste and smell – pleasant with a vague fishy tones.Tasters evaluated the control and experimental samples of products (respectively, without and with the introduction of PMA) by the intensity profile method using the developed characteristics. Individual evaluations of the experts were recorded in the tasting sheets, after which the taste profile of these samples of bakery products was built (Fig. 4).Physico-chemical quality parameters of the control and experimental samples of bakery products are pre-sented in Table 4. Fig. 4. Bread flavor profileTable 4Physico-chemical parameters of experimental and control samples of breadIndicator nameExperimental samples (with a protein-mineral supplement)Control samples (without protein-mineral supplement)Mass fraction of moisture , %31.1031.00Mass fraction of protein, %15.1010.25Mass fraction of fat, %0.700.85Mass fraction of carbohydrates, %*50.4556.55Mass fraction of minerals, %2.651.35Acidity, gram/L0.20.1Energy value of the product, kcal *262.99265.65*Data were obtained by calculation. The research results showed an increase in the amount of protein by 47.3%, minerals – by 96.3%.Table 5 shows the results of the amino acid (AA) content and comparative analysis of the amino acid scoring of experimental and control samples. Table 5Calculated indicators of amino acid score of experimental and control bread samplesEssential АAAmino acid content of FAO/WHO “reference” protein g/100gControl samples (without protein-mineral supplement)Experimental samples (with a protein-mineral supplement)AA content, g/100g proteinАA score*, %AA content, g/100g proteinАA score*, %Valin5.004.590.004.8997.80Isoleucine + leucine11.009.1883.4510.1992.64Lysine5.502.5245.813.6065.45Methionine + cystine3.502.6074.293.59102.57Threonine4.002.3057.503.2781.75Trypophan1.000.9191.001.03103.00Phenylalanine + tyrosine6.007.39123.167.44124.00Sum 36.0029.4–34.01–Biological value, % 86.8196.76Utility coefficient of the AA composition*, debt units0.620.79*Data were obtained by calculation. The table shows that the protein of breads with the addition of PMA is more balanced in composition. The index of biological value of protein is 124%, which characterizes its balance. The amino acid utilitarian coefficient increased with the addition of PMA to the standard bread recipe, which indicates the advisability of its introduction into the recipe to enrich the product with wholesome animal protein, which is so necessary for the growing organism. Tables 6 and 7 present the results of the study of minerals and the calculation of the satisfaction of their daily requirement in the classic and enriched bakery products at the consumption of 150 g of bread per day. Table 6Content of mineral substances in breadMineral contentExperimental samples (with a protein-mineral supplement)Control samples(without protein-mineral supplement)Daily requirement*Potassium, mg, %270.00220.002 500 mgCalcium, mg, %110.0050.001 000-1 200 mgMagnesium, mg, %50.0029.40400 mgSodium, mg, %730.00720.001 300 mgPhosphorus, mg, %220.00200.00800 mgIron, mg, %1.501.5010-18 mgManganese, mg, %0.090.092 mgZinc, mg, %0.550.5512 mgCopper, mg, %0.010.011 mgSelenium, mсg, %4.444.445-70 mсgChromium, mсg, %20.0020.0050-200 mсg*Based on MR 2.3.1.2432-08 “Norms of physiological requirements for energy and nutrients for various groups of population of the Russian Federation”.Table 7Calculated indicators in meeting the daily requirement of minerals in rye-wheat bread enriched with protein-mineral supplementMineral contentQuantity, mg/150 g of rye-wheat breadDaily requirementMeeting the daily requirement*Product functionality for this componentPotassium, mg, %405.002 500 mg16.2FunctionalCalcium, mg, %165.001 000 mg16.5Magnesium, mg, %75.00400 mg18.75Sodium, mg, %1 0951 300 mg84.23Phosphorus, mg, %330800 mg41.25Iron, mg, %2.2514 mg16.0Manganese, mg, %0.1352 mg6.75Not functionalZinc, mg, %0.8112 mg6.75Copper, mg, %0.0151 mg1.5Selenium, mсg, %6.6650 mсg13.32Chromium, mсg, %30.00150 mсg2.00*Use of 150 g of bread per day, %. The analysis of the obtained data showed that the content of calcium in enriched bread exceeds 2.2 times, potassium – 1.2 times, magnesium – 1.7 times. It can be seen that the ratio of Ca : P and Ca : Mg in the experimental sample is 1 : 2 and 1 : 0.19, respectively, whereas in the control 1 : 4 and 1 : 0.13, which indicates a good balance in the enriched products.It is known that the most favorable ratio of calcium and phosphorus in food is 1 : 1.2-1.5, calcium and magnesium – 1 : 0.25-0.3. Excess phosphorus leads to the leaching of calcium from bones, reduces iron absorption, increases the load on the kidneys. Excess magnesium negatively affects the absorption of calcium. In food products, in general, the ratio with phosphorus and magnesium, necessary for better absorption of calcium, is not maintained.The data in Tables 6 and 7 show that the enriched breads have a high content of the most important mineral elements in the diet (potassium, calcium, magnesium, sodium, phosphorus), that is, the product is functional. Of particular importance are trace elements that are not synthesized by the body (copper, zinc, manganese).Microbiological tests of the finished product, as well as the safety of the main and auxiliary raw materials, were carried out to assess the storage capacity of the products. As a result of the research, it was found that it is necessary to carefully control the raw ingredients of the formulation, especially the contamination of minced meat from cod carcass and whey. Also, a guaranteed shelf life for enriched loaves was established – 72 hours at a temperature not lower than 6°C, it is also possible to store at a temperature of –18°C for 3 weeks, followed by heating in the oven at 180°C for 5 minutes.Conclusions1. It has been inferred that introducing the fish pro-tein-mineral additives into the composition of bakery and flour confectionery products increases their bio-logical value while maintaining attractive organoleptic indicators.2. The technology of wheat biscuits enriched with fish protein has been developed, the optimal parame-ters of the formulation have been determined using the method of mathematical planning, an increase in the content of the mass fraction of protein by 47.5%, mineral substances – by 38.8% has been proved.3. The technology of rye-wheat loaves enriched with a protein-mineral additive obtained by partial disaggregation of cod carcass in whey (subcutaneous), occurring under the action of enzymes of fish muscle tissue, rennet enzyme and lactic acid for 4 hours at a natural pH of the reaction mixture equal to 5.9 ± 0.1, hydromodule 1 : 1 and the temperature is 22 ± 2°C.4. It is shown that the enrichment of rye-wheat bread with a protein-mineral composition increases the protein content by 70.2%, mineral substances – by 60.9%, reduces the amount of carbohydrates – by 13.3%. The content of calcium in enriched bread com-pared to traditional products is 2.2 times higher, potas-sium – 1.2 times, magnesium – 1.7 times.5. Analysis of the functionality of the finished product showed that the consumption of 150 g of en-riched bread satisfies the daily requirement (%): potas-sium – by 16.2; phosphorus – 41.25; magnesium – 18.75; sodium – 84.23; iron – 16.0; calcium – 16.5. The ratio of Ca : P and Ca : Mg in the experimental sample is respectively, 1 : 2 and 1 : 0.19, whereas in the control 1 : 4 and 1 : 0.13, which indicates a good bal-ance in the enriched products and allows us to recom-mend it for the nutrition of various segments of the population, including adolescents.