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Effect of Thermodynamic Parameters on Tomato Ripening and Chilling Injury under Heterogeneous Heat Treatment

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan

Citation:  2007 ASAE Annual Meeting  076269.(doi:10.13031/2013.23012)
Authors:   Jianbo Lu, Clément Vigneault, MarieThérèse Charles, G. S. Vijaya Raghavan, Bernard Goyette
Keywords:   heterogeneous, heat treatment, temperature, air velocity, tomato

A forced-air-twin-chambers insulated device was built to generate heterogeneous heat treatment. This treatment insured that half part of tomato in one chamber to be exposed to effective warm air at a controlled temperature of 39°C and uniform circulation at a velocity of 0.24m s-1; while the other half in the other chamber was exposed to lower temperature of 36°C or 37°C under 0.24m s-1, or at 36°C under 0.12 m s-1. Temperature control for both chambers was achieved using suitable instrumentation, while the air velocity could be modified and fixed at a desired level. The tested tomato fruits were randomly divided into four lots: one was used as control, two were uniformly treated, and the other was heterogeneously treated. Immediately after treatment the fruits were transferred to regular storage conditions at 14°C, to ripening at 20°C or to chilling injury (CI) at 2°C. Under all storage conditions, relative humidity was maintained high at 90-93%. Color, firmness, titratable acidity (TA), total soluble solid (TSS) and severity of CI were measured or evaluated subjectively at designed time. Results indicated that temperature difference between two chambers has significant effect on the uniformity of color--especially on chroma and redness represented by hue, slightly on firmness, TA and sugar acid ratio in the temperature range investigated. Decreasing the temperature difference between the two chambers or relatively increasing the air flowrate of upper chamber significantly improved the uniformity of quality, addressing the importance of improving the uniformity of heating media around each individual treated fruit.

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