Effects of pH on Measured Total Heme Pigment Quantities

Abstract

Various heme pigments, including myoglobin (Mb), hemoglobin, and cytochromes, are present in meat. These heme pigments can be used to evaluate meat color. An acetone–hydrochloric acid mixture (75:0.7) was used to extract and quantify heme pigments from a meat sample in the form of hematin. To evaluate color changes due to differences in meat pH, heme pigments were extracted from a variety of meat samples to determine whether the hydrochloric acid content could be adapted. A calibration curve was prepared based on the total amount of heme pigment extracted from Mb dissolved in a buffer solution (pH 4.1–11). No adverse effects, including reduced extraction efficiency or heme pigment decomposition, were observed at different pH values. The salt produced from the neutralization reaction during the extraction did not affect extraction efficiency. No differences in yield were observed between extraction solvents with varying proportions of hydrochloric acid (0.4–1.6 mL, 0.7–2.8%) for meat samples adjusted to pH 4.4 and unadjusted samples (pH 5.6–5.7). At pH 10.5, it tend to much the heme pigments were extracted with 1.4% hydrochloric acid, however with no significant differences in extraction yield from 0.7–1.4%. Therefore, 0.7% hydrochloric acid is suitable for extracting and quantifying all heme pigments in a meat sample.