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To ensure express control of food quality and safety, we developed an immunochromatographic test system for detection of the antibiotic clinafloxacin. The test system implements an indirect competitive immunoassay format based on the interaction of unmodified specific polyclonal antibodies with the antibiotic potentially present in the sample and the antibiotic–protein conjugate immobilized on the working membrane of the test strip. The detection of immune complexes formed on the membrane is carried out using a conjugate of anti-species antibodies and gold nanoparticles. We determined immunochromatography conditions that ensure the achievement of the minimum detection limit. At the assay duration of 20 min, the instrumental and visual detection limits of clinafloxacin comprise 0.3 and 10 ng/mL, respectively. The selectivity of the test system in relation to antibiotics from the class of fluoroquinolones was studied. To ensure the control of the contamination of honey with clinafloxacin and structurally related fluoroquinolones, we identified an optimal sample preparation regimen and confirmed the efficacy of the developed test system. [ABSTRACT FROM AUTHOR]

For the rapid control of the highly toxic phycotoxin microcystin-LR in seafood, immunochromatographic test systems have been developed and compared using two types of gold nanoparticles as markers, namely, spherical particles and nanoflowers. The test systems are based on an indirect competitive assay, in which the detectable immune complexes include native microcystin-LR-specific antibodies and nanoparticle-labeled anti-species antibodies. The developed test systems allow for the detection of microcystin-LR within 18 min with instrumental detection limits of 0.2 and 0.1 ng/mL when using spherical nanoparticles and gold nanoflowers, respectively. The visual detection limit is 1 ng/mL for both formats. The parameters of nanoparticles, which determine the analytical characteristics of the corresponding test systems are characterized. The applicability of the developed test systems for the control of contamination of fish and seafood (shrimp, octopus, squid, and mussels) combining rapid stages of sample preparation and immunochromatography has been shown. [ABSTRACT FROM AUTHOR]

An enzyme-linked immunosorbent assay (ELISA) has been developed to control the presence and estimate the content of soybean raw materials in meat food products. It is based on the binding of specific antibodies to the antigenic determinants of a soybean trypsin inhibitor. Due to the possible influence of enzymatic and high-temperature product treatments that can disrupt the native structure of the inhibitor and lead to its fragmentation, the analysis is based on the competitive interaction with antibodies of the antigen in the sample, which are immobilized in microplate wells. The conditions providing the minimum detection limit and high measurement accuracy were established to implement the ELISA. The developed assay was characterized by a duration of 60 min, a detection limit of 3.5 ng/mL, and a range of detectable concentrations of 7.7–110 ng/mL. It is shown that the proposed methodology can be used for the testing meat products. [ABSTRACT FROM AUTHOR]

The work presents the results of studies on the creation of a combined starter culture based on lactic and propionic acid bacteria and the functional properties of products based on it. It was shown that the fermented product obtained from a combined starter based on Lactococcus lactis ssp. cremoris CR201, Lactobacillus rhamnosus F and Propionibacterium shermanii E2 strains in a ratio of 2 : 1 : 6 (vol/vol), respectively, had a pronounced antagonistic effect on Escherichia coli and Staphylococcus aureus and causative agents of food spoilage Penicillium brevicompactum and Torulaspora delbrueckii, as well as ACE inhibitory activity in vitro. Bifidogenic and moderate hypotensive effects were demonstrated with in-vivo models. The addition of whey-protein hydrolysates to skimmed milk also leads to an increase in the growth of propionic acid bacteria and an increase in the number of viable cells in the finished fermented beverage, which increased its antimicrobial activity in vitro and bifidogenic effect in vivo. [ABSTRACT FROM AUTHOR]

A method for preparing antibodies that specifically recognize antibiotics of the fluoroquinolone group with the same radical in the first position of the quinolone nucleus is proposed. The specificity of rabbit antisera prepared at different cycles of immunization by changing the structure of the hapten in the composition of immunogens was characterized. The selected antibodies provided a group-specific analysis of 16 representatives of fluoroquinolones, including a combination of the following compounds that are controlled in animal products: ciprofloxacin, norfloxacin, pefloxacin, ofloxacin, and enrofloxacin. Using these antibodies, an indirect competitive enzyme-linked immunosorbent assay was developed that was characterized by a detection limit of ciprofloxacin of 0.2 ng/mL and a duration of 2 h. The assay was approbated for the detection of fluoroquinolones in milk. [ABSTRACT FROM AUTHOR]

Abstract: In this study, highly sensitive immunochromatographic analyses (ICAs) of ciprofloxacin (CIP) are developed. CIP is an antibiotic of the fluoroquinolone group that is widely used in veterinary practice and contaminates agricultural products. The analyses are based on various techniques that introduce gold nanoparticles as markers. It has been shown that the schemes allow for the detection of CIP within 15 min with an instrumental detection limit of 10 pg/mL for both schemes and visual detection limits of 10 and 2 ng/mL for direct and indirect schemes, respectively. The developed systems have been tested to detect the antibiotic in milk samples. It has been shown that ICA can determine CIP in milk using a simple procedure of preliminary sample preparation with preservation of high analytical characteristics. [ABSTRACT FROM AUTHOR]

An immunochromatographic method has been developed for the determination of ractopamine, a low-molecular, nonsteroidal growth regulator controlled in food due to toxicity. The developed analysis was characterized by an instrument detection limit of 0.05 ng/mL, a working range of 0.07‒0.28 ng/mL, and a visual detection limit of 0.5 ng/mL, which meets the requirements of sanitary and hygienic control. It is shown that the developed immunochromatographic test systems can be used to test meat products. [ABSTRACT FROM AUTHOR]

A technique was developed for fluorescence polarization immunoassay (FPIA) of ractopamine, a toxic low molecular weight nonsteroidal growth regulator belonging to the most controlled contaminants of food products of animal origin. The assay is based on the competition between a sample containing ractopamine and ractopamine-fluorophore conjugate for binding to antibodies. The competition is monitored via changes in the degree of fluorescence polarization for plane-polarized excitation light, which differs for the free and antibody-bound forms of the conjugate. The optimal assay conditions were established, ensuring a high accuracy and minimal detection limit. The developed assay demonstrated a detection limit of 1 ng/mL and a range of detectable concentrations of 2.3-50 ng/mL, which met the requirements of sanitary control. The duration of the analysis was 10 min. The possible application of the developed FPIA was demonstrated with testing of turkey meat. The speed and simplicity of the proposed assay define its efficiency as a screening tool for safety of foods. [ABSTRACT FROM AUTHOR]

An immunochromatographic method for determination of β-lactam antibiotic ampicillin has been developed. The method is based on the competitive interaction between antibiotic molecules contained in the sample and protein conjugate of penicillin immobilized on a membrane for binding with specific antibodies labeled with colloidal gold, which occurs during movement of the sample to be tested and reagents along the membrane. The completion of the test system ensures control of exceeding the maximum permissible content of the antibiotic in milk and dairy products (10 ng/mL). The possibility of testing milk, raw milk, and dairy products for 10 minutes at room temperature without sample pretreatment has been demonstrated. [ABSTRACT FROM AUTHOR]