As fish are perishable foods, their storage conditions require appropriate sanitary and temperature regimes. The producers commonly use various antibiotics to stop fish’s microbiological and biochemical processes. The current research aimed to examine antibacterial residues in frozen fish (Argentina, flounder, lackerda, mackerel, capelin, salka, saithe, herring, dorado, and pink salmon) to find their influence on the quantitative content of microorganisms and to determine the sensitivity of isolated psychrotrophic bacteria to antibiotics. A total of 75 samples were collected from the fillets of frozen fish species. These fish were imported from Norway (16 samples), Vietnam (24 samples), Russian Federation (8 samples), China (14 samples), New Zealand (2 samples), Italy (2 samples), United States (4 samples), and United Kingdom (5 samples). The obtained results revealed that aminoglycosides (Gentamicin, Kanamycin, Spectinomycin, Dihydrostreptomycin, Paromomycin, and Apramycin) were in 45.6 ± 1.4% of frozen fish. The findings indicated the presence of some antibacterial residues (Nalidixic acid, antibiotics: Apramycin, Kanamycin, Tiamulin, and Nafcillin) in frozen fish, the definition of which has not been specified in the EU Regulation. This gives grounds to prohibit the use or develop standards for the maximum permissible concentration of these antibacterial substances in fish. The most common psychrotrophic bacteria isolated from frozen fish without antibacterial residues were highly sensitive to antibiotics, including Penicillin, Tetracycline groups, and Aminoglycosides. Therefore, it can be concluded that the residual levels of various biocides found in fish are a source for the expression of multi-resistance genes, which can be transmitted to consumers in the food chain.

Нині екосистема є джерелом небезпечних факторів хімічного та радіологічного походження внаслідок активного розвитку промисловості, урбанізації, неконтрольованого застосування пестицидів, речовин хімічного захисту. Крім того наслідки катастрофи на Чорнобильській АЕС до теперішнього часу спричиняють радіаційне забруднення значної частини території України. Це, в свою чергу, призводить до накопичення токсикантів, радіонуклідів у кормах, надходження яких до організму тварин та харчових продуктів тваринного походження, становить загрозу для здоров’я людини. У зв’язку з цим актуальним є контроль та моніторинг за вмістом пестицидів, важких металів, мікотоксинів, радіонуклідів та інших токсикантів у кормах. Державний моніторинг кормів в Україні здійснюється на засадах оцінки ризику з метою контролю за дотриманням вимог чинного законодавства щодо безпечності та оцінки придатності продукту, а також задля недопущення обігу небезпечних кормів. Згідно Плану державного моніторингу на 2021 р. Державним науково-дослідним інститутом з лабораторної діагностики та ветеринарно-санітарної експертизи проведено лабораторний аналіз показників безпечності кормів для продуктивних та непродуктивних тварин із різних областей України. За результатами моніторингових досліджень одержано інформацію про рівень контамінації кормів пестицидами, мікотоксинами, важкими металами та радіонуклідами. Була встановлена невідповідність деяких зразків кормів вимогам безпеки в контексті наявності мікотоксинів. З огляду на це актуальними є заходи, спрямовані на мінімізацію ризиків для здоров’я тварин і людини, пов’язаних як з кормами безпосередньо, так і з навколишнім середовищем, забезпечення виробництва якісної продукції та попередження надходження до організму людини токсичних речовин у кількостях, що перевищують гігієнічні норми та становлять загрозу для здоров’я.

The article provides a systematic approach to quality control of measurements of total alpha-and beta-activity using a counter with a low background ALPHA / BETA COUNTING SYSTEM ALBA (mod. ALBA / LLAB) and software ALBA 2000 v.2.5.6. The purpose is to determine the compliance of these objects with the requirements of regulatory documentation. The spectrometry method is based on the physical concentration of radionuclides from the sample volume, measuring the rate of alpha, and beta radiation of the obtained dry residue of the sample, comparing the sample count rate with calibration values of activity, and calculating the total alpha, beta activity of the sample. The primary means of testing is a counter with a low background ALPHA / BETA COUNTING SYSTEM ALBA 200, the lower limit of measurements of the alpha activity, which is 0.02 Bq/l, and beta activity of 0.1 Bq/l, the relative random uncertainty of the measurement result is 60 % with a confidence level P = 0.95. The efficiency of registration on the alpha channel of 43 %, background on the alpha channel of 0,11 imp./min, for a measurement time of 60,000 s, the efficiency of registration on the beta channel of 30 %, background on the beta channel of 1,9 imp./min, for measurement time 60000 s. As a comparison sample for calculating total alpha activity, a sample with alpha radiation, 241Am (geometry 2π), is used. To calculate the total beta activity, a sample of beta-emitter of potassium sulfate with radionuclide is used at 40K (geometry 2π). The weight of the counting sample ranges from 200 to 1000 mg. The activity values are calculated automatically, using the software ALBA 2000, v.2.5.6. Measurement of the total activity of radionuclides in counting samples using the method should be performed only in calibrated geometries. At the same time, the safety requirements, personnel qualifications, and test conditions must be met. Quality control of measurements in the alpha, beta counter ALBA-2000 v.2.5.6. It is carried out in qualitative and quantitative ways.

Currently, one of the priority nanomaterials are nanoparticles of rare earth metals (RЕM) – cerium, lanthanum, gadolinium and others, which allows them to be successfully used as new natural feed additives (due to their antimicrobial and antioxidant properties) in order to increase the productivity of animals. However, the issue of redistribution in the body and accumulation of RЕMs in livestock products requires an adequate answer using sensitive and highly accurate quantitative research methods, in connection with which the determination of RЕMs in biological samples becomes extremely relevant. Within the framework of this study, the suitability assessment (validation) of the developed method for the determination of RЕM (lanthanum and gadolinium) in biological samples (serum, liver, kidneys) using atomic emission inductively coupled plasma (ICP OES) was carried out and the method of sample preparation in various matrices was adapted. Key working parameters were determined as evaluation criteria: limit of detection, limit of quantification, accuracy, correctness, convergence, reproducibility, selectivity, linearity, working range. It was established that this method demonstrates good linearity in the working range of 1.0-500.0 μg/kg(dm3) for Gadolinium and 0.5-500.0 μg/kg(dm3) for Lanthanum; the method is selective, sensitive, practical and accurate. The limit of detection LOD and limit of quantification LOQ for Gadolinium and Lanthanum are 0.1 and 0.05 μg/kg(dm3) and 1.0 and 0.5 μg/kg(dm3), respectively. The validation data obtained meet the requirements of the Eurachem Guideline and the IUPAC Harmonized Guideline for Single-Laboratory Validation, and the method for the determination of RЕMs in biological samples is suitable for a specific application according to ISO/IEC 17025:2019.

Unrefrigerated fish and seafood are dominated by mesophilic microflora. At the same time, during their storage in the conditions of refrigerating chambers, a cold-loving – psychrotrophic microbiota dominates, which, according to many scientists, causes organoleptic and chemical changes in fish and affects sanitary and hygienic indicators. Therefore, the microbiological assessment of frozen fish by the content of psychrotrophic microbiota, which participates in its reduced safety and quality, will make it possible to propose preventive measures against spoilage. The aim of the work was to develop a microbiological criterion for the hygiene of the technological process of frozen fish based on the assessment of the content of psychrotrophic microbiota. In the work, standard methods were used, in particular, the microbial number was determined in the samples at a temperature of (30 ± 1) ºС incubation of crops for 72 hours and at a temperature of (6.5 ± 0.5) ºС incubation for 10 days (psychrotrophic microbiota). It was established that during the storage of frozen fish at a temperature of -18 °С, the mesophilic microflora is inactivated, as a result of which its number gradually decreases. However, the intensity of inactivation of mesophilic bacteria in samples with insignificant microbial insemination is, on average, 1.4 times faster, compared to samples with a larger number of microorganisms. In our opinion, this is due to the fact that the composition of mysophilous microflora is largely represented by genera of bacteria that show tolerance to cold. At the same time, the psychrotrophic microflora of frozen fish does not become inactivated during the 8-month storage period at a temperature of -18 °C, and is more stable compared to the mesophilic one. That is, no significant increase or decrease in the number of microorganisms was noted. As a result, by the amount of psychrotrophic microflora of frozen fish, determined at any stage of storage, it is possible to judge its amount at the time of freezing. The amount of psychrotrophic microflora more objectively characterizes the hygienic conditions of production, compliance with the freezing temperature. The microbiological hygiene criteria of the technological process of frozen fish production were substantiated and developed based on the estimation of the amount of psychrotrophic microflora (n = 5; c = 3; m = 10000 CFU/g; M = 50000 CFU/g). These criteria indicate compliance with a set of hygienic measures from freezing to circulation of fish. Therefore, the determined microbiological criterion for the quantity of psychrotrophic microflora in frozen fish complements the existing methods of evaluating the hygiene of the technological process and aims to broadly assess the microbiological safety of frozen fish.