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QUANTITATIVE DETERMINATION OF METMYOGLOBIN AND TOTAL PIGMENT IN AN INTACT MEAT SAMPLE USING REFLECTANCE SPECTROPHOTOMETRY
Author(s) -
FRANKE WILLIAM C.,
SOLBERG MYRON
Publication year - 1971
Publication title -
journal of food science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.772
H-Index - 150
eISSN - 1750-3841
pISSN - 0022-1147
DOI - 10.1111/j.1365-2621.1971.tb06404.x
Subject(s) - metmyoglobin , pigment , chemistry , myoglobin , spectrophotometry , analytical chemistry (journal) , chromatography , biochemistry , organic chemistry
SUMMARY— A technique for determining the relative quantities of oxymyoglobin, metmyoglobin and total pigment concentration at the surface of on intact meat sample was developed. A Beck‐man DK‐2 spectrophotometer with reflectance attachment was used and spectra were recorded on the R A scale. The sample port of the spectrophotometer was modified so that a uniform and high intensity light beam measuring 0.5 × 0.6 cm reached the surface being evaluated. A sample holder was constructed so that known proportions of oxygenated and oxidized meat could be exposed to the light beam. A family of curves representing varying known amounts of metmyoglobin and oxymyoglobin were obtained. The height of the peak at 632 nm (ΔR A632 ) was directly related to the amount of metmyoglobin at the surface of the meat sample. For 100% oxymyoglobin, ΔR A632 was at a minimum and equal to R A750 . For 100% metmyoglobin, ΔR A632 was at a maximum and the height of the response depended upon the amount of total pigment present. A linear relation was obtained when ΔR A362 was plotted against percent metmyoglobin or against total pigment determined by the Hornsey (1956) method. The method requires making two readings of the meat samples at a single wave length. One reading of the sample followed by one reading of the same sample after oxidation with K 3 Fe(CN) 6 provides a quantitative evaluation of the metmyoglobin concentration and the total heme pigment concentration. The accuracy of the method may be improved by making multiple readings.