The suitability of using spectrophotometry to determine the concentration and purity of DNA extracted from processed food matrices

Species detection using DNA extracted from processed foods has become important in food authenticity testing. Extracting DNA from processed foods can be challenging, and it is considered essential to determine the concentration and purity of extracted DNA using spectrophotometry. While it has been found that chemicals from extraction reagents can interfere with readings at A260, the effect of chemical residue from a processed food matrix has not been investigated. The aim of this study was to determine whether spectrophotometry is suited to determine the concentration and purity of DNA extracted from processed foods. DNA was extracted from control DNA and six processed food matrices using 20 methods (including modifications) intended for processed foods. The concentration of DNA was measured using spectrophotometry, fluommetry and qPCR. Spectrophotometry was found to overestimate, whereas fluorometry underestimated the amount of extracted DNA. A novel approach was used to reduce the bias by calibrating the spectrophotometer using the extraction control instead of elution buffer. Finally, there was no relationship between the concentration, purity and amplifiability of DNA extracted from processed foods. Thus, spectrophotometry is not recommended as a suitable method to determine the concentration and purity of DNA extracted from processed foods.