Improved protein extraction from thermally processed shrimp (Litopenaeus vannamei) for reliable immunodetection via a synergistic effect of buffer additives

Extraction of targeted protein is a significant step for the quantitative detection of allergenic proteins, especially for detection in processed foods. To optimize the extraction step before immunodetection, six commonly used buffers were compared for their extraction efficiency and detectability of total proteins and tropomyosin (TM) from raw and thermally processed shrimp (Litopenaeus vannamei). Then the potential of three additives, including dithiothreitol (DTT), sodium dodecyl sulfate (SDS) and Tween 20, were applied to improve the extraction efficiency. The results showed the recovery of total proteins and TM extracted from processed shrimp was significantly reduced compared to unheated shrimps. Coca's buffer displayed higher efficacy in recovering total proteins and TM from raw and thermally processed shrimp. Moreover, principal component analysis (PCA) analysis revealed Coca's buffer with DTT, SDS, and Tween 20 additives displayed a synergistic effect in improving recovery of total protein and TM from raw and thermal processed shrimp. Indirect enzyme-linked immunosorbent assay (ELISA) and dot blotting analysis indicated the allergenicity of shrimp extracts could be highly suppressed by thermal treatment. Nevertheless, TM from various heated shrimps, except autoclaved samples, might have higher potential allergenicity, confirmed by western blotting analysis.