Volume 53, Issue 3, 2023

Microbial biomass is a promising source of essential macro- and micronutrients to be used in the food industry, e.g., protein, vitamins, essential amino acids, polysaccharide, etc. This article reviews scientific publications on the properties and composition of microbial biomass as a source of functional ingredients, its biological effectiveness, production methods, and composition.
The review covered research articles published in 2005–2021 and indexed in eLIBRARY.RU, Google Scholar, Scopus, Elsevier, and PubMed. It relied on such general scientific methods as analysis, generalization, and systematization.
Saccharomyces cerevisiae yeast and Aspergillus mycelial fungi appeared to be the most popular research objects. Most studies concentrated on the chitin-glucan-mannan complex of cell walls and protoplasmic biovaluable protein. Others featured the biocatalytic conversion of microbial polymers with the transfer of biologically valuable components into an enzyme-accessible state. Bioactive ingredients of microbial origin could be divided into sorbents, immunomodulators, neurotransmitters, antioxidants, and anticarcinogenics.
Microbial fermentolysates are a potential source of bioactive compounds for functional foods. However, the medical and biological properties of their minor bioactive components remain understudied while fermentolysates can yield new functional products fortified with essential amino acids and low-molecular bioactive peptides.

De-oiling fluid lecithin is a resource- and energy-intensive process that provides a phospholipid isolate with a high content of phospholipids. Ultrasonic exposure is one of the most effective and easy-to-implement physical methods that intensify this chemical-technological procedure. This article describes the effect of ultrasonic exposure on the efficiency of de-oiling fluid lecithins.
The research featured soy lecithin (fluid, partially de-oiled, phospholipid isolate). The de-oiling process involved acetone as a solvent and included three 10-min stages at a temperature of 40°C. The ratio of lecithin:acetone (by weight) was as follows: stage I – 1:7, stage II – 1:6, stage III – 1:5. The systems of fluid lecithin – acetone and partially de-oiled lecithin – acetone underwent ultrasonic treatment during the de-oiling process at different specific power and exposure time. As a result of filtration, phases separated into an acetone solution of neutral lipids and phospholipids. The phospholipid isolate was dried in a vacuum oven at 5 kPa and 40°C. Each stage ended with the following measurements: the content of phospholipids in partially de-oiled lecithins, the content of phospholipids in the phospholipid isolate, and the extraction degree of neutral lipids after distilling the solvent from the acetone miscella.
The specific power in the lecithin – acetone system was 0.28 W/cm³ at de-oiling stage I and 0.36 W/cm³ at stages II and III. Three minutes of ultrasonic exposure at stages I and II and two minutes at stage III reduced the acetone consumption by 1.2 times. The resulting phospholipid isolate yielded by 3.3% more phospholipids than the control sample, which presupposed no ultrasonic treatment.
Ultrasonic exposure proved to be an effective and solvent-saving three-stage method that intensified the process of de-oiling fluid soy lecithin. The study specified the optimal technological modes for obtaining a phospholipid isolate with a high content of phospholipids (98.6%), which can be recommended as a food additive.

Ice cream is a popular cold dessert. Its air phase consists of tiny bubbles with an average diameter of 15–60 µm. New ice cream formulations depend on the way the composition and production factors affect the air phase. As a result, ice cream producers need new time-saving and reliable methods to determine dispersion. The research objective was to create a computer program for marking the position of centers and diameter of air bubbles on microscopic images of a bounding circle type.
The review part included 20 years of Russian and English publications on microscopic research methods in ice cream production indexed in Web of Science and Russian Research Citation Index. Microscopic images of ice cream air phase were obtained using an Olympus CX41RF microscope with a magnification of ×100. The automatic markup program employed the Python programming language, the Keras machine learning library, and the TensorFlow framework. The models were trained using the NVIDIA GTX video accelerator.
The review showed that the dispersion of ice cream air phase depends on its composition and the freezing parameters whereas bubble formation is usually described in line with the existing foaming theories. A training data set was obtained by manual labeling of microscopic images. The optimal number channels in the convolutional layers of a neural network with LeNet-type architecture was determined, which made it possible to classify images as spheres or non-spheres with an accuracy of ≥ 0.995. The sliding window method helped to determine the limits of the neural network triggering for the sliding window method were determined, which reached 7.5% of the diameter with lateral displacement and 12.5% with scaling. The developed algorithm automatically marked bubbles on microscopic images. The error in determining the average diameter was below 1.8%.
The new method for automated calculation of the number and diameter of air bubbles in ice cream proved to be user-friendly. It can be found in public domain, and researchers are free to adapt it to solve various computer vision issues.

Pempek is an authentic traditional dish of Indonesian cuisine. As a popular food, it needs to be both tasty and nutritious. Mashed pumpkin can add some health-beneficial properties to the traditional pempek and reduce its carbohydrate content. This research featured pempek made of farmed toman fish (Channa micropeltes), which is an affordable raw material. The research objective was to evaluate the consumer acceptance of the experimental pempek based on its sensory assessment and a folding test. This research also revealed the proximate composition, β-carotene, and amino acids in the pempek samples.
The research procedure included the following stages: making pumpkin puree; making pempek by substituting tapioca flour with pumpkin puree (control: 0%, Formulation 1: 10%, Formulation 2: 20%); sensory assessment and folding test; proximate analysis; β-carotene analysis; and amino acid analysis.
A greater proportion of pumpkin puree improved the appearance, color, aroma, flavor, and texture values of the experimental sample. Based on the folding test, the elasticity of pempek decreased as the pumpkin share increased. Pumpkin puree improved the quality of pempek in terms of its protein, moisture, ash, carbohydrate, β-carotene, and amino acid composition. Formulation 2 with 20% of tapioca flour substituted with pumpkin puree showed the best results for protein (7.91%) and amino acids (10.27%), as well as the lowest carbohydrate content (26.76%).
Mashed pumpkin proved to be an excellent substitute of tapioca flour in the traditional Indonesian pempek fishcake as it improved both its sensory profile and nutritional value.

Economic entities involved in food production interact with a large number of counterparties and depend on their integrity. They have to check their potential business partners before cooperating. Contractual due diligence is a service provided by consulting and audit firms that use a variety of tools, e.g., databases and online services, to collect and analyze information. This research considered the main areas of contractual due diligence and assessed the tools involved.
The authors used the common methods of comparison, generalization, and synthesis to describe the main due diligence stages and digital tools.
Information about the counterparty was collected in three areas: legal capacity, financial position, and business reputation. The study focused on the stage of summary, analysis, and profiling. The authors determined the role of digital technologies at each stage, compared their performance, and defined their limitations.
The research revealed the potential of various digital tools for contractual due diligence. The results may help due diligence experts to plan the profiling process.

Microbiological contamination changes the qualitative and quantitative profile of food, which makes it an important issue of food safety systems. Finished products with components of animal origin or combined vegetable and livestock raw materials are especially prone to microbiological contamination. This review features the most common sources of microbiological contamination and its prevention in finished products.
The review covered 20 years of English and Russian scientific articles and standards indexed in Scopus, ScienceDirect, PubMed, and eLIBRARY.RU. The descriptors included microbiological contamination, food raw materials, and ready-to-eat products. The analysis involved some older publications, provided they possessed a high scientific relevance and/or a high citation index. The search criteria concentrated on the detection of microbiological contaminants in food raw materials and food products in Russia and abroad. The percentage of detections for individual groups of microorganisms was calculated as opposed to their total number.
The data obtained can be summarized as follows. Regular industrial monitoring can minimize the risk of microbiological contamination. Complex finished products have a higher risk and require heat treatment. Composite products that cannot be succumbed to additional heat treatment need new technologies that minimize microbiological contamination, e.g., intensive cooling, shock freezing, electromagnetic processing, protective food coatings, etc.
Even a small amount of animal raw materials may cause extra risk of contamination with Listeria monocytogenes, Salmonella enteritidis, etc. A mix of different raw materials changes the microbiological profile of the finished product. As a result, finished products have to be monitored throughout the entire shelf-life cycle, regardless of the percentage of animal raw material in the formulation.

The food industry knows a lot of methods to determine the total antioxidant activity. The potentiometric method includes the mediator system of potassium hexacyanoferrates (K₃[Fe(CN)₆]/K₄[Fe(CN)₆]) and has proved to be quite effective in assessing the antioxidant activity of food products. This method is simple and cheap but its interference issues still remain understudied. This research covered 30 potential interfering substances in beverages and their reactivity toward the mediator system of potassium hexacyanoferrates.
The experiment featured carbohydrates (glucose, fructose, sucrose, lactose, maltose), dyes (E102, E110, E124, E129, E132, E133), preservatives (E210, E221, E222, E223, E236, E260), sweeteners (E420, E421, E950, E952, E954), and acidity regulators (E296, E330, E331iii, E334, E337, E338, E363, E386). The potential and pH were determined by the potentiometric method in a mediator system solution in the absence and presence of the abovementioned substances. Cysteine and ascorbic and gallic acids served as controls.
Glucose, sucrose, and maltose did not interfere with the analysis, while fructose and lactose showed an insignificant positive interference of unspecified mechanism. Malic (E296), citric (E330), tartaric (E334), and phosphoric (E338) acids increased the potential of the mediator system by lowering the pH. However, these interference effects were observed only at high concentrations in an electrochemical cell and were leveled after a sixfold dilution. Indigo carmine (E132), sodium sulfite (E221), sodium hydrosulfite (E222), and sodium metabisulfite (E223) were oxidized by potassium ferricyanide and showed significant positive interference. Potassium ferricyanide was capable of oxidizing compounds other than natural antioxidants.
The industrial use of indigo carmine is limited due to its poor light stability, while sulfites are popular components in winemaking. Sulfite interference is of particular concern in the analysis of white wines and is typical of other antioxidant activity methods. The obtained data can correct the results of the potentiometric antioxidant activity tests if the concentration of the interfering substance is known.

As a rule, modern confectionery products have added nutritional value, which makes them functional products. As a popular snack, biscuits are a promising object for fortification with functional ingredients. This article introduces a new formulation for biscuits fortified with soy protein.
The research featured crushed soy protein obtained using a patented technology (patent No. 2218816). The experimental biscuits included a mix of wheat flour with 2.5–15.0% soy protein. The control sample was represented by commercial biscuits of the Arktika brand. Physicochemical and other quality indicators were determined by standard methods. The isoflavonoid test involved high performance liquid chromatography with methanol:water eluent.
The experimental biscuits had a higher nutritional value; the absorption indicator fell from 196 to 172%. The crude gluten content dropped from 30.7 to 28.4%. The optimal content of soy protein in the new formulation was below 7.5% of the total mass of wheat flour. A higher mass fraction brought the absorption index below the standard value (˂ 170%) and spoiled the porosity and brittleness. Compared with the control sample, the nutritional value of the experimental sample improved as follows: protein – by 21.6%, fat – by 14.1%, minerals – by 11.1%, isoflavones – by 140.8% (from 4.83 to 11.63 mg/100 g). Total carbohydrates dropped by 6.5%.
The formulation demonstrated good prospects for industrial production. The new biscuits with soy protein can be classified as functional food: compared to the conventional biscuits, the recommended daily intake (100 g) for phosphorus increased from 11.7 to 20.1%, vitamin E – from 12.6 to 18.0%, for isoflavones – from 9.6 to 23.2%.

Sourdough bakery products have a wide range of tastes and aromas, an extended shelf-life, and other benefits that are important for food producers and consumers. Recent years have seen a growing research interest in the microbiome of bakery sourdoughs. The research objective was to generalize, systematize, and analyze modern data on spontaneous fermentation starters, their production methods, and their role in the technological process at modern bakeries.
The study featured domestic and foreign monographs, research articles, and patents related to various aspects of the production and commercial use of spontaneously fermented baking starters. The search covered publications indexed in PubMed and eLIBRARY.RU in 2000–2022. The sources were selected based on such indicators as completeness, consistency, reliability, and relevance. The obtained data were analyzed and systematized in line with the method of apperception and holography.
The analysis focused on the factors that affect the microbiome of baking starter cultures, in particular, spontaneous fermentation. Another aspect included the effect of the raw materials used at the stage of breeding spontaneous fermentation starter cultures on their quality indicators. The transformation of bioactive compounds in the process of sourdough fermentation proved to be an increasingly relevant research matter. Food producers are looking for more effective tools to develop bakery products with specific nutritional properties, e.g., lower glycemic index, increased content of bioactive nutrients, reduced acrylamide content, low gliadin allergenicity, etc.
The isolation and profiling of microorganisms included in the microbiome of spontaneous fermentation sourdough cultures is of practical interest because new strains might produce starter cultures intended for various target audiences.

Hibiscus sabdariffa L., also known as edible roselle, belongs to the Malvaceae family and is native to West Africa. In Nigeria, its dried petals are processed by boiling and filtration into a non-alcoholic beverage called Zobo. Commercial Zobo often includes artificial sweeteners that improve its taste. As a result, local food science needs new formulations with natural and health-beneficial sweeteners. The research objective was to produce a Zobo drink with different blends of date fruit juice as a natural sweetener, as well as evaluate its proximate, physicochemical, and sensory properties.
The control Zobo drink (Zcon) involved an artificial sweetener. The ratios of Zobo to date juice were 90:10 (ZD10), 80:20 (ZD20), 70:30 (ZD30), 60:40 (ZD40), and 50:50 (ZD50). The samples underwent proximate and physicochemical analyses, as well as a sensory assessment on a nine-point hedonic scale.
The physicochemical analysis showed that Sample ZD50 with the 50:50 ratio had the highest pH (3.5) and sugar content (9.5°Bx) while the control sample had the lowest pH (2.5) and sugar content (0.9°Bx), with all samples showing significant (p ≥ 0.05) differences. The proximate analysis also showed a wide range of results (p ≥ 0.05). The control sample demonstrated the highest moisture content (97.0%) whereas Sample ZD50 had the highest ash and lipid content of 0.8 and 4.8%, respectively. Sample ZD50 also had the highest protein (2.23%) and crude fiber content (2.49%). Sample ZD40 with the 60:40 ratio had the highest carbohydrate content. In terms of mouthfeel and taste (p ≥ 0.05), the control sample demonstrated the highest scores while the lowest score belonged to Sample ZD10 with the lowest proportion of date juice. The best results for general acceptance belonged to the control, followed by ZD40 (60:40) and ZD50 (50:50).
Date juice proved to be an effective sweetener that improved the nutritional profile of Zobo. However, the sensory analysis showed that consumers preferred the control sample with the artificial sweetener.

Probiotic starters are a biological product based on lactic acid bacteria. Their metabolic characteristics determine the properties of the final products. This study evaluated the bacterial composition of a starter culture at various time intervals during the fermentation of a probiotic dairy product.
The starter consisted of Streptococcus salivarius ssp. thermophiles, Lactobacillus delbrueckii ssp. bulgaricus, Bifidobacterium bifidum, Bifidobactreium animalis ssp. lactis, Bifidobacterium longum, Lactobacillus acidophilus, and Lacticaseibacillus casei. Pasteurized milk served as the object of fermentation. The starter culture was activated in sterilized skimmed milk. Sampling occurred throughout the entire fermentation process (0, 3, 6, 9, 12, 15, and 18 h). To determine the microbiome of the substrates, the authors used the next-generation high-throughput sequencing that targeted V3 of 16S rRNA gene.
The fermentation resulted in a decrease in Bifidobacterium and an increase in Lactobacillus, which peaked (97.5%) after 15 h of fermentation. Each sampling showed that the count of Streptococcus went down. Eventually, Lactobacillus replaced all other genera, including Bifidobacterium, probably, as a result of pH going down during fermentation. The optimal values for the proliferation of Lactobacillus (pH = 4.2–4.4), which were registered after 18 h, turned out to be too low for the productive growth of Bifidobacterium.
The research demonstrated the changes in the bacterial composition of the dairy base during fermentation. The high-throughput sequencing proved to be an efficient tool in controlling probiotic fermentation processes.

Wheat is a vital agricultural crop whose phytopathogens include fungi of the genera Fusarium and Alternaria. Synthetic pesticides, which are used to combat them, have a negative impact on the environment. Therefore, there is a need for developing safe and effective biopesticides. We aimed to create a consortium of extremophilic microorganisms isolated from natural sources to protect wheat from the diseases caused by Alternaria and Fusarium fungi.
Ten isolates of extremophilic microorganisms were tested for their antimicrobial activity against Escherichia coli and their antagonistic activity against phytopathogens. Based on the results, we developed microbial consortia and evaluated their effectiveness in protecting wheat from phytopathogens.
Five of the strains under study showed the highest activity, three of which were biocompatible, namely Leclercia sp., Sphingomonas paucimobilis, and Lactobacillus plantarum. Four consortia were created from these microorganisms, of which consortium B (with a 2:1:1 ratio of the strains, respectively) proved the most effective. In particular, it increased the area free from the phytopathogen by 4.2% compared to the average values of its individual microorganisms. Also, the consortium had a phytostimulating effect on wheat seedlings (germination of 73.2–99.6%) and protected the seeds infected with phytopathogens from morphometric changes.
The resulting consortium can be used as a biopesticide since it is highly effective in protecting wheat from Alternaria and Fusarium pathogens.

Peas (Pisum sativum L.) are rich in protein, B vitamins, and dietary fiber, represented by hemicellulose and pectins. In terms of amino acids, pea proteins are as close to the reference protein as possible. The limiting amino acids of pea protein are sulfur-containing, i.e., methionine and cysteine. Peas are also rich in lysine, which is the limiting amino acid for wheat flour. Therefore, products of pea processing can expand the range of commercial high-protein foods, including functional bakery products. The research objective was to develop a technology for functional bread from a mix of wholemeal pea flour and wheat gluten.
The study featured baking wheat flour, wheat gluten, wholemeal pea flour of San Cipriano and Vega varieties, dough samples, and ready-made bread. The carbohydrate-amylase complex of flour was studied using an Amilotest AT-97 device. The starch content was determined by the polarimetric method. The spectrophotometric method served to test the flower samples for protein while the Kjeldahl method was applied to the bread samples. The rheological properties of the dough were studied on a Reotest 2 viscometer. The sensory evaluation relied on a panel of experts, and the chemical composition was revealed by calculation and analytically.
The wholemeal pea flour had a lower starch gel viscosity compared to the wheat flour sample. A greater amount of flour added during kneading increased the viscosity of the resulting dough. The acidity was rather high: 7.2 and 9.4 degrees for San Cipriano and Vega samples, respectively, and so was the autolytic activity (≤ 80 s). These useful qualities made it possible to reduce the technological process by 115 and 145 min. The resulting bread demonstrated good physical, chemical, and sensory indicators. The high-protein raw materials increased the protein content in bread by 41.9–46.4%, compared to the control sample, which equaled 33.1–34.2% of the recommended daily intake per 100 g of bread.
The optimal ratio of wholemeal high-protein pea flour and wheat gluten was 20/80 for the San Cipriano samples and 30/70 for the Vega variety.

Due to its protein component, donkey’s milk is a multifunctional product with a wide range of beneficial physiological properties. It is known for its antioxidant, anti-inflammatory, rejuvenating, antimicrobial, and antitumor effects. However, the milk of Kyrgyz donkeys has not received proper scientific attention in this respect. This study analyzed the seasonal amino acid profile and biological value of milk obtained from Kyrgyz donkeys.
The donkeys belonged to the Kyrgyz breed and inhabited the highlands of the Chui Region, Republic of Kyrgyzstan. The sampling took place in April, July, and September. The amino acid composition of milk proteins was determined by capillary electrophoresis. The biological value of proteins was assessed by amino acid score, index of essential amino acids (Auxerre index), utility ratio of essential amino acids, and utility ratio of amino acid composition.
The analysis revealed 18 amino acids, including eight essential ones. The total content of amino acids in the spring samples was 1840.07 mg/100 g. In the summer samples, this value peaked at 2037 mg/100 g; in autumn, it dropped to 1264.35 mg/100 g. The changes could be explained by the seasonal differences in the diet. The ratio of essential to non-essential amino acids approached 1:1. The milk also proved to contain arginine, which is an essential amino acid for a juvenile organism. In the spring samples, its content was 2.5 times as big as in the autumn ones. Leucine and isoleucine were responsible for 1/3 of the essential amino acids (322.60 ± 19.35 mg/100 g). The summer samples demonstrated the maximal content of some other essential amino acids, except for valine and tryptophan, which appeared to be the limiting essential amino acids for donkey’s milk in the autumn period. Total essential amino acids in the spring, summer, and autumn samples amounted to 54.24, 59.26, and 34.77 g/100 g, respectively, which exceeded the value for the reference protein (27.46 g/100 g).
Kyrgyz donkey’s milk proteins were of high biological value, regardless of the season, which means that donkey’s milk can become part of new functional products.

The food industry uses sonochemical treatment as part of emulsification, homogenization, and dispersion, as well as to modify viscosity and structure. Starch is one of the most common food ingredients, both as a raw material or a property-modifying additive. The research objective was to study the effect of sonochemical action on the structural and mechanical properties of wheat starch suspensions.
The study involved suspension samples with 10% wheat starch. The suspension samples were treated with ultrasound using an ultrasonic device Volna-M model UZTA-1/22-OM or in an ultrasonic bath (22 kHz; 100, 150, 300, and 400 W). The treatment time was 15 and 30 min. The rheological, physical, and textural properties were recorded according to conventional methods before and after the treatment.
The ultrasonic treatment caused mechanical damage to the starch, making it more accessible to moisture when heated. As a result, the structural, mechanical, and rheological properties of starch suspensions changed. All the studied suspensions had a non-Newtonian character. The ultrasonic treatment increased their consistency coefficient from 28.12 to 152.75 µPa·s. The gelatinization temperature of all experimental starch suspensions dropped from 63.4 to 61.0°C. The short high-power ultrasound treatment reduced the strength of gels to 1.25 N compared to that of native starch gel (4.28 N).
In this research, the ultrasound treatment of wheat starch suspensions modified the structural, mechanical, and rheological profile of starch and proved able to replace some conventional starch modification procedures, i.e., chemical, physical, or enzymatic. The new approach can provide modified starches of a preset quality while reducing energy costs and processing time.

Tomatoes (Solanum lycopersicum L.) are one of the most popular vegetables in the world. These days, Russian consumers prefer tomatoes labeled as organic. However, the agricultural industry often lacks instrumental methods to confirm the organic status of tomatoes. Isotope mass spectrometry is a promising method that can detect tomatoes that fail to meet organic standards. Isotopic values of total nitrogen and total carbon can be used to identify tomatoes as those grown on the field or as those cultivated in greenhouses enriched with carbon dioxide.
The research featured 16 samples of tomatoes, 14 of which were purchased in Russian retail chains. Two samples were grown on the field without chemical fertilizers. The composition of stable carbon and nitrogen isotopes in the samples was determined using an IRMS Delta V Advantage isotope mass spectrometer with additional auxiliary modules.
In the greenhouse tomatoes, δ¹³C values ranged from –44 to –32‰. In the samples obtained from a conventional greenhouse, δ¹³C values ranged from –30 to –24‰. Six samples proved to have been grown in artificial carbon dioxide atmosphere. Three samples demonstrated borderline values of δ¹³C and δ¹⁵N; they were impossible to identify as organic or conventional, both in terms of artificial carbon dioxide and fertilizers.
Isotope mass spectrometry proved to be efficient in detecting falsified organic products. Tomatoes grown with carbon dioxide enrichment had lower isotope values of total carbon than organic tomatoes. The obtained values also made it possible to tell between organic and chemical fertilizers.

Meat is an inherent part of human diet. Its quality develops at different stages of production, storage, and processing. In this respect, the stage of aging is especially important. This technology makes it possible to regulate biochemical processes in meat raw materials. Long-term dry aging is a promising method that presupposes conditions that limit the growth of microorganisms. The transformations in the protein component are an important but understudied aspect of meat quality formation during dry aging.
The research featured Hereford beef carcasses of Siberian breeding. The samples were isolated from the inner part of bone spinal-lumbar cuts after 21, 35, and 42 days of dry aging under the following conditions: 0–1°C, 74–75% relative humidity, 0.5 m/s air velocity. The samples were subjected to dry aging after 24 h at 4°C. The fractional composition of proteins was controlled by vertical electrophoresis in a Mini-Protean Tetra System chamber. The amino acid composition was defined by high-performance liquid chromatography in a Shimadzu LC-20 Prominence liquid chromatograph with a Shimadzu SPD20MA diode-matrix detector and a Kromasil C-18 separation column. The protein digestibility was measured by sequential exposure to pepsin-trypsin proteinase system under simulated gastric digestion.
Long-time dry aging triggered proteolysis under the action of endogenous enzymes. The electropherogram analysis showed that the proteolytic changes in high-molecular myofibrillar proteins of high-quality beef became more pronounced after a longer maturation period. The distribution of protein fractions by dry aging stages indicated a different rate of degradation of contractile, regulatory, and cytoskeletal proteins. As a result, the structural integrity of muscle fibers degraded, the meat grew tender, and the proteins became more available to digestive enzymes. The amino acid and protein digestibility analyses in vitro demonstrated an increase in the nutritional value of beef and the availability of proteins to the action of proteinases after 42 days of dry aging.
Long-term dry aging of high-quality beef increased the digestibility of muscle proteins as a result of proteolysis that accompanied the accumulation of low-molecular fractions. According to the amino acid analysis, the optimal result was most pronounced on day 42 as proven by the moderate oxidative changes in proteins.

Cyanobacterium sp. IPPAS B-1200 is a cyanobacteria strain that belongs to the rare genus Cyanobacterium, family Cyanobacteriaceae fam. nov. Studies devoted to the isolation of secondary metabolites from this strain concentrate mostly on the fatty acid composition while the issue of isolating and identifying exopolysaccharides remains understudied. However, polysaccharides from cyanobacteria are of scientific and economic interest in the framework of biotechnology, medicine, pharmacology, etc. The research objective was to study the effect of the physicochemical conditions of cultivation and the composition of the cultural medium on exopolysaccharide production.
Cyanobacterium sp. B-1200 were grown under 7500 ± 50 lux (12 h light/12 h dark). The dry cell weight was determined by gravimetry and a calibration plot that illustrated the dependence of the biomass amount on the degree of absorption at a wavelength of 750 nm. The amount of polysaccharides in the culture liquid was assessed by the Anthrone-sulphate method. The extraction was carried out by alcohol precipitation. The method of ultrasonic dispersion was used to destroy the cell walls of cyanobacteria.
The experimental study revealed the optimal parameters for the extraction and purification of exopolysaccharides from the culture medium. Removal of sodium bicarbonate from the medium and a 300%-increase in its concentration raised the yield of polysaccharides. The optimal value of active acidity for the synthesis of polysaccharides was pH = 6 while the optimal temperature for their accumulation was 35°C. The largest amount of biomass was obtained at 25°C. Intense white illumination contributed to the greatest release of exopolysaccharides into the culture medium; red-white illumination affected the morphology of cyanobacteria cells. During the extraction, the concentration, temperature, and nature of the extractant proved to be the most important factors. For example, isopropanol produced the highest yield while butanol triggered the least effective response.
The optimal extraction and purification modes for polysaccharides were as follows. For ultrasonic processing, the best results were obtained at a power of 20 W after 5 min. For freeze drying, the rational parameters were 8 h at –15°C.