Water-extractable zinc protoporphyrin IX in Parma ham predominantly exists as complexes with hemoglobin and myoglobin

• Published in: Food bioscience Vol. 40; p. 100870
• Main Authors: Wang, Hung-Cheng, Hayakawa, Toru, Kumura, Haruto, Wakamatsu, Jun-ichi
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.04.2021
• Subjects: cured meats; ham; heme; Hemoglobin; hydrophobic interaction chromatography; Myoglobin; nitrates; nitrites; Parma ham; polyacrylamide gel electrophoresis; Proteolysis; protoporphyrin; water; water solubility; Western blotting; zinc; Zinc protoporphyrin IX; Myoglobin; Hemoglobin; Zinc protoporphyrin IX; Parma ham; Proteolysis
• ISSN: 2212-4292; 2212-4306
• DOI: 10.1016/j.fbio.2020.100870

Zinc protoporphyrin IX (ZnPP) is the dominant red pigment in nitrate/nitrite free dry-cured hams such as Parma ham. A large amount of ZnPP in Parma ham is water-extractable and is thought to exist in complexes with unidentified water-soluble proteins. This study was done to clarify these ZnPP-binding proteins to provide insight into the ZnPP-forming mechanism. The ZnPP-binding proteins were purified from Parma ham water extract (PHE) through a combination of hydrophobic interaction chromatography, urea-PAGE, and SDS-PAGE, and finally identified as hemoglobin (Hb) and myoglobin (Mb). According to western blotting analysis of PHE, ZnPP-Hb and ZnPP-Mb complexes were observed as both intact and proteolyzed forms, and the formation of these complexes was independent of proteolysis. The amount of total ZnPP-Hb complexes was ~3-fold higher than total ZnPP-Mb complexes. These results suggested that the heme destabilization in the heme pocket is important rather than proteolysis for forming ZnPP-binding proteins. •Zinc protoporphyrin IX (ZnPP)-binding proteins were separated using urea-PAGE.•ZnPP-hemoglobin complex was predominant over ZnPP-myoglobin complex.•Heme destabilization may be crucial for forming ZnPP-binding proteins.•Formation of ZnPP-binding proteins was independent of proteolysis.