Detection of soybean by real-time PCR in the samples subjected to deep technological processing

K A Kurbakov,M Yu Minaev,E A Konorov,V N Zhulinkova

doi:10.21323/2414-438x-2019-4-4-23-27

Abstract

During deep technological processing, DNA of food product components (specifically, in canned foods) is subjected to strong degradation, which makes the PCR-based food components identification more difficult. In this work, a primer-probe system is proposed, which was selected for the multi-copy region of long terminal repeat (LTR) of soybean (Glycine max). We confirmed its high sensitivity and specificity for soybean detection by real-time PCR. Using the selected system, we successfully analyzed the samples of meat-and-plant canned foods and other food products subjected to deep technological processing — tofu, preserved tofu, soy sauces, confectionary products containing soy lecithin. To compare with these samples, real-time PCR was carried out using the primer-probe system selected for the single-copy le1 gene. In terms of sensitivity, the use of the primer-probe system specific to the single-copy region was significantly inferior to the primer-probe system specific to the LTR region. The difference in the rate of degradation of these genomic DNA regions of Glycine max was found.

Highlights

Soybean and products of its processing are widely used in the food industry
Methods based on the polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay (ELISA) are applied most frequently
We developed a highly sensitive method for soybean detection in food samples based on selection of a multi-copy region of genomic DNA for primer design

Summary

Introduction

Soybean and products of its processing are widely used in the food industry. This category of raw materials is often used for meat product falsification (replacing part of meat raw materials or exceeding a quantity specified in TS). To increase PCR sensitivity, multicopy DNA markers are used, in particular, DNA of organelles: mitochondrial [5] or plastid [6] This approach in combination with highly effective DNA extraction enables identification of a targeted matrix in low concentrations in deep processed samples [7]. Ballin et al used the elements called the chicken repeat 1 (CR1) with the copy number of approximately 26,650 in the chicken genome and the trinucleotide repeat containing 5 (TNRC5) with the copy number of approximately 100,000 in the pork genome for comparative quantitative assessment of pork and poultry meat in the model samples [8] This approach had high theoretical sensitivity of the method. The use of these regions was necessary for designing a primer system

Methods

Results

Conclusion