Requirements for the application of protein sodium dodecyl sulfate-polyacrylamide gel electrophoresis and randomly amplified polymorphic DNA analysesto product speciation

Raw, cooked, fried, smoked and gravad (brine-cured) products were analyzed by Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of proteins and by randomly amplified polymorphic DNA (RAPD) in order to ident ify the species used in their manufacture. The discriminatory power of SDS- PAGE was dependent primarily on the composition and secondarily on the size of the gels: the Laemmli buffer system with 15% acrylamide and 0.087% pipe razine diacrylamide separating gels resolved more discriminant protein band s than any of the commercial gels tested. Some of the processing conditions induced alterations in the protein patterns that made identification dubio us. Differentiation even between closely related species was easier by RAPD than by SDS-PAGE. Neither the processing conditions nor the tissue from wh ich the DNA was extracted had a significant effect on the RAPD profiles. Fo r identifications based on SDS-PAGE, one should use an optimized gel compos ition and separate the sample under analysis in the same gel as the referen ces. For RAPD-based identifications, the unknown sample should be amplified together with reference samples and separated in the same gel.