Application of histochemical and immunohistochemical techniques for detection of lung tissue in cooked sausage

Background: Using unauthorized tissues in sausage is a common food adulteration in some parts of the world. Aims: This study was designed to compare the accuracy of histochemical and immunohistochemical techniques for the detection of lung tissue in cooked sausage samples. Methods: Samples with different levels of sheep lung tissues (1, 2.5, and 5%) and a control group were prepared and stained histochemically using H E, Masson trichrome, and Periodic Acid-Schiff (PAS) stainings, and immunohistochemically using two different commercially-available antibodies of TTF1 Pan-cytokeratin. Results: The highest positive results of lung tissue detection were achieved in sausage samples stained with anti-TTF1 immunohistochemical staining method. Both anti-TTF1 and anti-pan-cytokeratin immunohistochemical techniques detected all contaminated sausage samples treated with 50 g/kg lung tissues. Anti-TTF1 staining method had the highest odds ratio (7.4), followed by anti-pan-cytokeratin method (6.0). Reversely, PAS staining method had the lowest odds ratio (0.21), followed by Masson trichrome method (1.7). Additionally, anti-TTF1 method had the highest (1.8-31.0) confidence intervale (95%), while PAS had the lowest (0.02-2.1). Totally, the odds ratio of lung tissue detected by immunohistochemical methods were higher than those detected by histochemical staining. Conclusion: This is the first report on the comparison of histochemical and immunohistochemical techniques for lung tissue detection in cooked sausage. Anti-TTF1 immunohistochemical staining proved to be the most useful technique for the detection of unauthorized lung tissue in cooked sausages.