Comparison of three types of methods for the isolation of DNA from flours, biscuits and instant paps

Three types of methods for the isolation of DNA from food products, namely, cetyltrimethylammonium bromide solubilization with liquid-phase extraction (CTAB-LPE), chaotropic solid-phase extraction (SPE) and non-chaotropic SPE were compared on the basis of yields. These were measured by UV spectrophotometry, fluorimetry of the SYBR Green I-DNA complex and by the determination of the maximum amplifiable dilution. The latter parameter, which proved to be the most informative, was determined using polymerase chain reaction (PCR) for soya, maize and wheat, respectively, in series of flours, biscuits, chocolate-containing biscuits and instant paps (a baby food preparation) containing the respective major ingredients. All three types of DNA isolation methods performed well for practically all food products analysed, yielding greater than or equal to10(2)xminimum amplifiable DNA concentration. Chaotropic SPE performed in most cases as well as to CTAB-LPE and may be recommended as a faster alternative for isolating DNA in PCR-based analyses of these types of food products.