Influence of oxygen and temperature on the respiration rate of fresh-cut cantaloupe and implications for modified atmosphere packaging

The respiratory behavior of fresh-cut melon under modified atmosphere packaging at various temperatures was characterized to assess the potential for shelf life extension through low-oxygen and to generate information for the development of appropriate packaging conditions. Cantaloupe melon (Cucumis melo var. cantalupensis 'Olympic Gold') cubes were packaged and stored at 0, 5, 10, and 15 °C. Packages attained gas equilibrium after 5 days at 10 °C, 6 days at 5 °C, and 10 days at 0 °C. In cubes stored at 15 °C, decay started before steady-state gas levels were reached. Respiration rates were measured and respiratory quotient calculated once steady-state O2 and CO2 partial pressures were achieved inside the packages. O2 uptake increased with temperature and O2 partial pressure (pO2 pkg), according to a Michaelis-Menten kinetics described by. Respiratory parameters were modeled as an exponential function of temperature: RO2 = {[1.34 × 10-17 × e(0.131 × T) × pO2 pkg]/[1.15 × 10-24 × e(0.193 × T) + pO2 pkg]} (R2 = 0.95), Q10 = 3.7 = 84 kJ·mol-1. A good fit to the experimental data was also obtained considering, as constant: RO2 = {[4.36 × 10-14 × e(0.102 × T) × pO2 pkg]/[0.358 + pO2 pkg]} (R2 = 0.93), Q10 = 2.8 = 66 kJ·mol-1. These results provide fundamental information to predict package permeability and steady-state pO2 pkg required to prevent anaerobic conditions and maximize shelf life of fresh-cut cantaloupe. The kinetics of respiration as a function of pO2 suggests that no significant reductions in respiration rate of fresh-cut cantaloupe can be achieved by lowering O2 levels.