Comparative study of DNA extraction methods for soybean derived food products

The present work describes the comparison of four DNA extraction methods applied to a wide range of soybean derived food products. The methods included the commercial kits NucleoSpin and GeneSpin, the CTAB, and the Wizard methods. The protocols have been compared for their extraction efficiency, evaluated by the determination of yield and purity of DNA extracts, as well as amplifiability. All the methods produced DNA suitable for PCR amplification for the majority of analysed foods, with the exception of soybean sauces and some processed foods. The NucleoSpin and GeneSpin methods showed the best results for DNA yield and purity, when applied to soybean flours and protein isolates. The CTAB and Wizard methods were generally well suited to all kind the food matrices tested. The extraction of processed foods, such as drinks, desserts or vegetarian foods was better achieved with the CTAB or the Wizard methods as both produced high number of amplifiable extracts. The four methods showed similar performances for real-time PCR amplification.