Influence of oxygen concentration and temperature on respiratory characteristics of fresh-cut green onion

The characteristics of the respiration rates in precut green onion, as influenced by oxygen levels and temperature, were examined to provide design factors for modified atmosphere packaging (MAP). Fresh-cut green onions (Allium fistulosum L.) were prepared and sealed, with and without a CO2 absorbent, in gas-tight glass containers that had initially been purged with air or a gas mixture (O2 9%/N2 balance). The containers were stored at different temperatures (0, 10, 20 °C). At 10 °C, the maximum O2 uptake rate (Vm) and the O2 concentration at half-maximum (Km) uptake rate were 30.95 mL kg−1 h−1 and 1.63%, respectively. Regardless of temperature, the lower O2 limit was estimated to be about 1.0% O2 on the basis of respiratory quotient (RQ) increase. Respiration of cut green onion was dependent on O2 concentration as well as temperature, as shown by applying the Michaelis–Menten type model and the Arrhenius equation. However, the presence of CO2 had little effect on O2 uptake of cut green onion at relatively high O2 concentrations (≤20%).