Hyperbaric Treatment and Fresh Tomato Fruit Respiration Rate and Respiratory Coefficient

A dynamic respirometer has been designed and built to measure the respiration rate (RR) and respiratory coefficient (RQ) of fresh fruit and vegetable under pressure varying from 1 to 9 atm_abs. This respirometer was tested on tomato for establishing the technical performance of the system. A method was developed to calculate the RR and RQ using the difference between the CO₂ and O₂ concentration at the air inlet and outlet or the respirometer. The solubilisation of some CO₂ within the internal liquid of the tomato fruit restrained our capability to determine the real RR and RQ during the transient period at the beginning of the hyperbaric treatment. This natural solubilisation process needs further study to elaborate proper method to measure the RR and RQ during the transient period. However, after reaching the gas equilibrium within the entire system, the respirometer allowed the determination of the pressure range that generates significant effects on the RR and RQ of tomato without generating physical or physiological damage. A replicable effect on the RR and RQ of pressurized tomato was identified. Tomato fruit subjected to 3, 5 and 7 atm_abs treatments had a RR reduction of 11%, 16% and 20% compared to untreated fruit, respectively. Submitting tomato fruit to 9 atm_abs generated irreversible damage and caused anaerobic respiration. These results were in line with the results presented in the literature showing a reduction of CO₂ and C₂H₄ production when pre-climacteric fruits were stored at 5 atm_abs.