Method for Determining the Respiration Rate of Horticultural Produce Under Hyperbaric Treatment

A method was developed to determine the metabolic respiration rate (RRm) of fresh produce during the transient period at the beginning of a hyperbaric treatment. This method allowed for the correction in the apparent respiration rate (RRap) by considering the dilution effect of flushing the system and the error associated with gas solubilisation as the gas partial pressure varied. The dilution process was simulated by using the general equation for exhaust ventilation, thus allowing for the elimination of the dilution effect during the calculation of the net respiration rate (RRN). The error associated with the CO2 solubilisation in the flesh of the produce was solved by measuring the CO2 solubility in the tissues of tomato at various CO2 partial pressures and using this value to generate a mass balance of CO2 within the system. The RRm was estimated by incorporating the initial respiration rate (RRi) of untreated fruits with the respiration rate at equilibrium (RRe). The kinetic of the RRm was proposed to follow a negative exponential equation. The constant value (k) of the RRm model was found to decrease exponentially with the partial pressure of CO2 at equilibrium which affected the amount of gas solubilised and the time to reach equilibrium. The developed method should be validated for the RRm of other produce during the transient period at the beginning of a hyperbaric treatment.