TY - BOOK

T1 - Protein Oxidation and Protein-Polyphenol Binding in Meat During Chill Storage

AU - Zainudin, Asraf

PY - 2019

Y1 - 2019

N2 - Protein oxidation was studied in meat patties stored in high-oxygen-modified atmosphere packaging (HiOx-MAP) (80% O2) with and without light exposure and compared to meat patties subjected to forced oxidation by addition of relevant oxidants (myoglobin, Fe(II) and H2O2). Results showed that light exposure exhibited the highest protein polymerization degree and resulted in the lowest thiol concentration as well as intrinsic tryptophan fluorescence signal after storage for 9 days as compared to forced oxidation and control sample without light. Interestingly, no significant loss of other amino acids or formations of selected oxidation products were detected by UHPLC analysis. Protein-polyphenol binding was studied by adding 4-methylcatechol (4MC), which is a small phenol with the same chemical structure as the B-ring of flavonoids, to meat before storage. The identification and quantification of a specific protein-polyphenol binding compound, cysteine-4- methylcatechol (Cys-4MC) adduct, were performed by LC-MS/MS analysis using a synthesized Cys-4MC adduct as standard. Thiol loss was measured in order to relate the formation of Cys-4MC adduct to the loss of thiols. Protein–polyphenol binding was also studied by protein blotting with nitroblue tetrazolium (NBT) staining, which is a non-specific method covering a broader range of binding types. Contributions of light exposure to the Cys-4MC formation were also investigated by introducing photo-oxidation as the source of oxidation to the meat. The loss of thiols and the formation of Cys-4MC adduct were complimentary to one another in the meat samples. Samples with the highest Cys-4MC adduct amount, which was light exposed sample stored under oxygen atmosphere (12 ± 2 nmol/mg MPI), had the lowest thiol concentration (2.6 ± 0.3 nmol thiol/mg protein). In comparison, the fresh meat had 32 ± 3 nmol thiol/mg protein. The formation of Cys-4MC adduct was dose-dependent with the highest 4MC dose (1500 ppm) resulting in the highest Cys-4MC adduct formation and the lowest thiol concentration. The protein blot with NBT staining showed no differences between samples stored with and without light exposure on the formation of protein-polyphenol adducts. Storage conditions such as exposure to light combined with oxygen increased the amount of Cys-4MC adduct compared to storage in the dark under oxygen-containing atmospheres.

AB - Protein oxidation was studied in meat patties stored in high-oxygen-modified atmosphere packaging (HiOx-MAP) (80% O2) with and without light exposure and compared to meat patties subjected to forced oxidation by addition of relevant oxidants (myoglobin, Fe(II) and H2O2). Results showed that light exposure exhibited the highest protein polymerization degree and resulted in the lowest thiol concentration as well as intrinsic tryptophan fluorescence signal after storage for 9 days as compared to forced oxidation and control sample without light. Interestingly, no significant loss of other amino acids or formations of selected oxidation products were detected by UHPLC analysis. Protein-polyphenol binding was studied by adding 4-methylcatechol (4MC), which is a small phenol with the same chemical structure as the B-ring of flavonoids, to meat before storage. The identification and quantification of a specific protein-polyphenol binding compound, cysteine-4- methylcatechol (Cys-4MC) adduct, were performed by LC-MS/MS analysis using a synthesized Cys-4MC adduct as standard. Thiol loss was measured in order to relate the formation of Cys-4MC adduct to the loss of thiols. Protein–polyphenol binding was also studied by protein blotting with nitroblue tetrazolium (NBT) staining, which is a non-specific method covering a broader range of binding types. Contributions of light exposure to the Cys-4MC formation were also investigated by introducing photo-oxidation as the source of oxidation to the meat. The loss of thiols and the formation of Cys-4MC adduct were complimentary to one another in the meat samples. Samples with the highest Cys-4MC adduct amount, which was light exposed sample stored under oxygen atmosphere (12 ± 2 nmol/mg MPI), had the lowest thiol concentration (2.6 ± 0.3 nmol thiol/mg protein). In comparison, the fresh meat had 32 ± 3 nmol thiol/mg protein. The formation of Cys-4MC adduct was dose-dependent with the highest 4MC dose (1500 ppm) resulting in the highest Cys-4MC adduct formation and the lowest thiol concentration. The protein blot with NBT staining showed no differences between samples stored with and without light exposure on the formation of protein-polyphenol adducts. Storage conditions such as exposure to light combined with oxygen increased the amount of Cys-4MC adduct compared to storage in the dark under oxygen-containing atmospheres.

UR - https://soeg.kb.dk/permalink/45KBDK_KGL/1pioq0f/alma99123569386505763

M3 - Ph.D. thesis

BT - Protein Oxidation and Protein-Polyphenol Binding in Meat During Chill Storage

PB - Department of Food Science, Faculty of Science, University of Copenhagen

ER -