Genetically modified soybeans: false-positive detection in fermented natural soybean (tempe)

Area of Science:

• Food Science and Technology
• Biotechnology
• Microbiology

Background:

• Tempe production involves fermenting soybeans with Rhizopus species.
• Distinguishing between natural and genetically modified (GM) soybeans, like Roundup Ready (RUR) soybeans, is crucial for food safety and regulatory compliance.
• Accurate quantification of GM content in fermented foods is essential.

Purpose of the Study:

• To investigate the impact of fermentation on the detectability of Roundup Ready (RUR) soybean content in tempe.
• To identify potential interferences in quantifying RUR soybean using ELISA during tempe fermentation.
• To determine if fermentation by specific microorganisms generates substances that cross-react with RUR detection.

Main Methods:

• Tempe was prepared using mixtures of natural and RUR soybeans, fermented with natural Rhizopus sp.
• Quantification of RUR soybean content was performed using an ELISA plate test.
• Control experiments involved fermenting non-RUR soybean tempe to assess false-positive signals.

Main Results:

• The ELISA signal for RUR soybean content decreased during the fermentation process.
• Fermentation of non-RUR soybean tempe resulted in a false-positive RUR signal.
• A cross-reacting substance was generated specifically in non-RUR soybean during fermentation by various Rhizopus species, Mucor rouxii, and Aspergillus awamori.

Conclusions:

• Standard ELISA methods for RUR detection may yield inaccurate results in fermented tempe due to the generation of cross-reacting substances.
• The fermentation process itself, particularly with certain microorganisms, can create compounds that interfere with the detection of GM soybean traits.
• Further method development is needed for accurate quantification of RUR soybean in fermented products like tempe.