Method for Measuring the Mass Fraction of Soybean Trypsin Inhibitor: Features of Development and Certification

   Modern industrialization increases the requirements for the accuracy of identifying allergens, especially those that have a negative impact – soy trypsin inhibitor (STI). Correct determination of the presence of STI in food products containing soybeans is key for product safety control and labeling. The authors set a goal to develop and certify a method for measuring the mass fraction of STI using an enzyme-linked immunosorbent assay – a technique that may increase the specificity of the method and avoid false-negative results.

   The object of research was a method for analyzing food allergens – an enzyme-linked immunosorbent assay carried out with a set of reagents produced by XEMA LLC. In the process of developing the measurement method, the main methodological factors influencing the accuracy of the measurement results were optimized: sample weight, time of its extraction, time and speed of sample centrifugation, ratio of supernatant liquid to ELISA buffer, incubation temperature, interaction time of the allergen-antibody complex with the coloring agent, the wavelength for measuring absorbance, and the maximum time for measuring absorbance after introduction of the stop reagent.

   The developed method was tested during an interlaboratory experiment with the participation of 5 laboratories. Metrological characteristics were established in accordance with RMG 61–2010. The proposed method was certified in accordance with the requirements of GOST R8.563-2009, No. 102–FZ. The method has a wide range of quantitative determination of the mass fraction of STI from 0.5 to 25.0 μg/kg (ppb) with a detection limit of 0.1 μg/kg (ppb) and a relative error of 40 %. Based on the results of the research, the Federal Information Fund for Ensuring the Uniformity of Measurements (FIF) registered a certified method for identifying and quantifying the content of non-infectious food allergens of plant protein origin in samples of all types of food products and objects related to the requirements for food products, swabs taken from working surfaces during production control using reagent kits for an enzyme-linked immunosorbent assay produced by XEMA LLC No. FR.1.31.2022.43884. The method is intended for use in testing laboratories involved in monitoring the quality and safety of manufactured products; it can be used to confirm product compliance with the mandatory requirements established in the Technical Regulations of the Customs Union TR CU022/2012.

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