Effect of thyme oil on the preservation of vacuum-packaged chicken liver

In this study fresh chicken liver meat was stored under vacuum packaging (VP) and under refrigeration (4 °C). The following treatments were used: V (control samples, stored under VP), VT1 (thyme oil; 0.1% v/w, stored under VP) and VT2 (thyme oil; 0.3% v/w, stored under VP). Lipid oxidation was low, as judged by determination of malondialdehyde (MDA) values, in vacuum-packaged chicken liver meat, both in the absence or presence of thyme essential oil (EO) during the entire storage period. Of the color parameters (L*, a*, b*) monitored during storage time, L* (lightness) values for vacuum-packaged chicken liver, irrespective of treatment, showed a varying trend, whereas a* (redness) values for V, VT1, and VT2 liver samples decreased, showing no significant differences. As determined by sensory analysis the observed shelf life of chicken liver samples was longest for VT2 (>12 d) followed by VT1 (12 d) and control (V) samples (7 d). Our results suggest that a Brochothrix thermosphact count (7 log CFU/g) and appearance of visible colonies can be used as indicators of chicken liver spoilage.