FTB journal

Threshold Level and Traceability of Roundup Ready^® Soybeans in Tofu Production

Zorica Nikolić^1*, Gordana Petrović¹, Dejana Panković², Maja Ignjatov¹, Dragana Marinković¹, Milan Stojanović¹ and Vuk Đorđević¹

¹Institute of Field and Vegetable Crops, Maksima Gorkog 30, RS-21000 Novi Sad, Serbia
²Educons University, Vojvode putnika 85-87, RS-21208 Sremska Kamenica, Serbia

Article history:
Received: February 1, 2017
Accepted: August 2, 2017

Key words:
DNA degradation, GMO, labelling, legislation, tofu, traceability

Summary:
The aim of this study is to assess DNA degradation, DNA amplification, and GMO quantity during tofu production. Soybean seeds were spiked with Roundup Ready^® soybeans (RRS) at 0.9, 2, 3 and 5 % (by mass), to assess the level of RSS that would be of practical interest for threshold labelling. Real-time polymerase chain reaction (PCR) was more effective than conventional PCR in the analysis of raw soymilk, okara, boiled soymilk and tofu. The negative effect of grinding and mechanical manipulation was obvious in the okara sample prepared with 3 and 5 % RRS, where GMO content was reduced to (2.28±0.23) and (2.74±0.26) %, respectively. However, heating at 100 °C for 10 min did not cause significant degradation of DNA in all samples. The content of RRS in the final product, tofu, was reduced tenfold during processing, ranging from 0.07 to 0.46 %, which was below the labelling threshold level. The results are discussed in terms of global harmonization of GMO standards, which could have the positive effect on the trade of lightly processed foodstuffs such as tofu, especially regarding the labelling policies.

*Corresponding author:  +381 21 4898 150 
                                           zorica.nikolic@ifvcns.ns.ac.rs