Quantification of zinc-porphyrin in dry-cured ham products by spectroscopic methods Comparison of absorption, fluorescence and X-ray fluorescence spectroscopy.

Zinc-protoporphyrin (Zn-pp), which has been identified as the major pigment in certain dry-cured meat products, was extracted with acetone/water (75%) and isolated from the following meat products: Parma ham, Iberian ham and dry-cured ham with added nitrite. The quantification of Zn-pp by electron absorption, fluorescence and X-ray fluorescence (XRF) spectroscopy was compared (concentration range used [Zn-pp]=0.8-9.

Mass spectrometric evidence for a zinc-porphyrin complex as the red pigment in dry-cured Iberian and Parma ham.

Extracts containing red pigment complexes from the two types of dry-cured hams, Italian Parma and Spanish Iberian ham, were obtained using water and acetone as extraction solvents followed by a crude purification with C18 column filtration. The purified extracts were then analyzed spectroscopically by recording absorption and fluorescence spectra (λ(ex)=420nm), which both indicate the presence of chemically identical red chromophores with properties similar to a complex of transition metals and protoporphyrin IX. Electrospray ionization mass spectrometry (ESI-MS) in the positive ion mode confirms the presence of identical chemical compounds.

Changes in Zn-porphyrin and proteinous pigments in italian dry-cured ham during processing and maturation.

Substitution of iron with zinc in myoglobin during maturation of Parma ham to yield zinc porphyrin extractable by 75% vol/vol acetone/water solution and detectable by fluorescence spectroscopy, was found to occur concomitant with protein modification in myoglobin. The content of zinc porphyrin increases throughout the whole processing and maturation of Parma ham, from I(fl) 0.1±0.

Zn-porphyrin formation in cured meat products: Effect of added salt and nitrite.

Zn-porphyrin (Zn-pp) was quantified by fluorescence spectroscopy in the cured and dry cured meat products: Parma ham, Iberian ham, dry-cured ham with added nitrite, cooked ham with added nitrite, raw ham meat, raw bacon and Karree-Speck. The highest amount of Zn-pp was found in dry-cured Parma ham and Iberian ham, while the use of nitrite as curing agent was found to inhibit completely the formation of Zn-pp in meat products. A positive correlation between both Zn content and Fe content and the logarithmic transformed Zn-pp content (measured as fluorescence intensity I(fl)) was found for the different cured and dry cured meat products, with correlation coefficients of 0.