Comparison of the proteomic profile of pork byproducts during their storage

In this article, the proteomic profiles of pork by-products (snout, tongue, liver, kidney, spleen) were studied by comparative method on the first day and the fifth day of their storage. Two-dimensional electrophoresis according to O'Farrell was used for the aims of this article, while the results were further processed in ImageMaster software. Proteomic maps of by-products showed clear changes in protein composition after visualization and images analysis. There was a decrease and increase in manifestation intensity of some proteins. The study of the obtained electrophoregrams with the help of references resources allowed identifying various compounds in the by-products. 9 protein fractions with various intensity of manifestation were found on the day 1st and 5th. On the 1st day the following substances were intensively manifested: in the liver — glutathione peroxidase 4 (22.3 kDa), LEAP-2 (8.8 kDa); in the kidneys — quinone oxidoreductase (34.9 kDa); in the spleen — glycoprotein CD59 (13.7 kDa), in the patch — protein flint (49.07 kDa). It is noted that these proteins play their role in stopping certain processes in cells, like oxidation, microbial activity, and accumulation of toxic substances. These processes can worsen the quality of raw materials, and further lead to spoilage of the food product. On the 5th day of storage the highest intensity of manifestation of glyceraldehyde-3-phosphate dehydrogenase (35.8 kDa) in the liver was observed; superoxide dismutase [Cu-Zn] (15.8 kDa) was noted in the kidneys, colony-stimulating factor (16.2 kDa) was observed in the spleen and glutaredoxin –1 (11.8 kDa) in the tongue. In its turn, on the fifth day these chemical processes manifested themselves more intensely, as the fatty acids and glucose broke down. To obtain more accurate results, the proteins were compared by their volume. Among the identified fractions the highest expression was observed in LEAP 2 (8.8 kDa) on the first day, and in glyceraldehyde-3-phosphate dehydrogenase (35.8 kDa) on the fifth day. The least change in the intensity of manifestation was noted for superoxide dismutase [Cu-Zn] (15.8 kDa), which volume increased during storage by 13% for 5 days. The analysis of the obtained electrophoregrams allowed identifying various compounds, tracing the changes in the qualitative composition of protein in by-products during various periods of their storage. The obtained data demonstrate the transformation of protein molecules during storage, which makes it possible to determine the changes and quality of the food products.