Pork pH Determined by ISFET Electrode Shows Higher Value than Glass Electrode

Ion-Sensitive Field-Effect Transistor (ISFET) electrode is expected to be useful for on-line nondisruptive measurement of pork pH values. The aim of this study was to compare pork pH values measured by using ISFET electrode without temperature compensation with conventional glass electrode. Porcine longissimus muscles harvested from 32 carcasses were subjected to pH measurement at 4 day after slaughter. ISFET pH values were significantly higher than glass electrode pH value of 5.66. The least squares means of ISFET pH was 6.11 at the surface of pork sample and 6.14 at the inner part of muscle. Although there were some statistical significant correlations between ISFET and glass electrode pH values, correlation coefficients between them were too low for the estimation of glass electrode pH value by ISFET pH value. These results clearly demonstrated that pH values measured by ISFET electrodes without temperature compensation become higher than those of glass electrode. Thus, appropriate corrections of values, e.g. temperature compensation and estimation using regression, would be necessary when using ISFET electrode for pork pH measurement.