Effect of water activity and temperature on degradation of 5′-inosine monophosphate in a meat model system

The influence of water activity (a_w) (0.7,0.8 and 0.9) and temperature (80° and 120 °C) on the degradation of meat flavor precursor inosine monophosphate (IMP) was studied in a meat fiber model system. Breast and leg muscle from Indian domesticated layer chicken (Gallus gallus) were washed repeatedly with 0.1 mol/l phosphate buffer of pH 6 to obtain pigment free and with minimum content of natural IMP in muscle fiber. The freeze-dried breast and leg meat fiber had a protein content of 86.5±0.48% and 85.6±0.50%, respectively. The IMP contents (mg/100 g) of leg muscle fiber (7.3±0.60) was higher (P?0.05) than in the breast meat fiber (5.1±1.20). The degradation of IMP was temperature-dependent (P?0.05) in both types of meat fiber systems. In the samples of a_w 0.8, the IMP degradation in breast meat fiber system was lower (P?0.05) than in a_w at 0.7 and 0.9 samples, when treated at 80 °C, whereas, there was no significance difference (P>0.05) in the degradation of IMP at a_w 0.7 and 0.9 when heated at 120 °C. The degradation of IMP in leg meat fiber model system at higher a_w (0.9) was more (P?0.05) as compared to lower a_w (0.7 and 0.8) at 80 °C, while the samples treated at 120 °C, the degradation of IMP at a_w 0.8 and 0.9 was more (P?0.05) than at a_w 0.7.