Improved DNA Extraction for Dairy and Blood Products: A Comparative Evaluation of Yield, Purity, and PCR Compatibility

DNA must be efficiently extracted from samples to accurately test the authenticity of food, particularly from processed matrices in which DNA integrity may be compromised. We systematically evaluated the efficiency of extracting DNA from dairy and blood products by four methods, namely SDS-CTAB, SDS-isopropanol precipitation, guanidine isothiocyanate magnetic beads, and a commercial kit. The guanidine isothiocyanate-magnetic bead method yields high quantities and purity of DNA; for example, the yield obtained from chicken blood samples was 318.34 ± 4.77 ng/µL, with an A260/A280 ratio ranging from 1.8 to 2.0. The processing time of this method was compared with the DNA Extraction Kit shorter by 40% and unlike methods such as the SDS-CTAB protocol, does not require the use of toxic reagents such as phenol or chloroform, meeting green chemistry requirements. Among the dairy and blood samples tested, it enables the extraction of DNA in quantities comparable to those obtained using commercial kits; moreover, the DNA yield achieved is 20–30% higher than that of these kits. Furthermore, this method is free from the limitations associated with protein contamination and amplification instability often encountered in protocols such as the CTAB-SDS and SDS-isopropanol methods. The magnetic bead approach was adaptable for complex matrices and demonstrated strong tolerance to coexisting contaminants, thereby improving extraction performance in challenging food samples. The magnetic bead surface functionalization and buffer systems could be improved to further increase their versatility. This method enables reliable DNA extraction and advanced technical support for DNA analysis.