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

Citation:   No Citation available.
Authors:   Jianbo Lu, Bernard Goyette, Marie Thérèse Charles, Clément Vigneault, Valerie Orsat, G S Vijaya Raghavan
Keywords:   Non-uniform, heterogeneous, heat treatment, chilling injury, firmness, color, tomato, taste

Abstract An experimental setup consisting of a forced-air-twin-chambers insulated device was built to generate a non-uniform (heterogeneous) heat treatment. The heterogeneous treatment insured that half part of tomato in one chamber to be exposed to warm air at a controlled temperature of 39.5C and uniformly circulating at a velocity of 0.24m s-1, while the other half in the other chamber was exposed under unheated, controlled and stable conditions (23C, 0.24m s-1). Temperature control for both chambers along with the desired fixed air flow rate is achieved using suitable instrumentation. The tested tomatoes were randomly divided into five lots: one was used as control, two were uniformly treated, and the other two were heterogeneously treated. Immediately after treatment the fruit were transferred to regular storage at 14C, to ripening at 20C or to chilling injury (CI) at 4C. Color, firmness, titratable acidity (TA), total soluble solid (TSS) and severity of CI were measured or evaluated subjectively at designed time. Results indicated there existence of statistically significant difference between heated and unheated part for tested tomatoes in terms of color, and CI. As result of relative consistently higher value of TA and TSS, no significant difference in the taste indictor, suger:acid (TSS:TA) ratio, was noticed. The result implied that ripening process of heated part was delayed in particular period, and this delay was similar to the contrast between uniformly heated tomato and its control. The observed difference might be explained by the fact that the effect of heat treatment on tomato is localized rather than systemic. These findings addressed that ensuring uniform heat condition is of paramount importance to attain the desired effect. It is suggested to develop systems with media such as RF or microwave, or to optimize the layout of material treated with conventional media.

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