Development of an Efficient Method to Extract DNA from Refined Soybean Oil

Recently, soybean oil has become the most consumed genetically modified (GM) vegetable oil globally. To monitor products derived from GM sources, DNA-based analysis methods are being widely adopted, particularly to control the authenticity of several food products including oil. Considering that DNA isolation from foodstuffs is the first step in the detection of GM organisms, we compared five different methods to extract high quality DNA from refined soybean oil. We used ultraviolet spectrophotometry, nested polymerase chain reaction (PCR), and real-time PCR to evaluate DNA yield and purity, and the sensitivity of the optimized method was evaluated. According to our results, the most effective DNA extraction method was the cetyltrimethylammonium bromide–NucleoSpin Food Kit method. Using this method, 21–225 DNA copies were isolated from 1 mL soybean or blended oils, and the minimum ratio of soybean oil that could be detected from a mixture of soybean and peanut oil was 5%. To summarize, we report a novel method that combines pre-concentrating oils and commercial kits. This optimized DNA extraction method advances the traceability of soybean oils for authenticity issues and transgenic detection.