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The effect of heat pre-treatment (45 °C/25 min), applied to whole fruit, and post-cut calcium dips in 1 and 2 g/L CaCl solutions on respiration rate and texture preservation of kiwifruit slices was studied. During a 9-day period, packages' atmosphere composition, slices' firmness, pectin content and sensory scores were evaluated. Histological observations of samples were also performed. Neither heat pre-treatment nor calcium dips alone were effective in diminishing respiration rate of the slices but the application of both treatments revealed a synergistic effect on respiration rate reduction. Calcium-dipped fruit slices showed better firmness preservation. Post-cut calcium dips, alone or combined with heat pre-treatments, yielded slices presenting higher insoluble/total galacturonic acid ratio, indicating formation of calcium pectates. Slices from heat-pre-treated fruits, even in the absence of calcium, also revealed insoluble/total galacturonic acid ratio similar to calcium-treated slices, supporting, despite the lower firmness value, a more structured tissue, as observed in SEM microphotographs. Sensory and physical-chemical parameters obtained were correlated. The effectiveness of calcium treatment was equally observed for both tested concentrations during a 9-day shelf life period. [ABSTRACT FROM AUTHOR]

An experimental hyperbaric system was designed and built to explore the effect of hyperbaric treatment on the respiration rate (RR) and respiratory quotient (RQ) of tomato. It consists of five containers that can be individually pressurized from 1 to 9 atm. The respirometer was equipped with a flow meter, control valve, pressure transducer, CO and O gas analyzer, and type T thermocouples that are all connected to a data acquisition and control card. A software interface was programmed to allow control of the air flow rate through the proportional valve of the flow meter based on a proportional-integral-derivative algorithm system. Hyperbaric treatments have been performed on tomato fruit, and it was observed that RR was inversely proportional to pressure. [ABSTRACT FROM AUTHOR]