Impact of sugar reduction on the glass transition temperature and sorption isotherm of freeze-dried tomato powder - INRAE - Institut national de recherche pour l’agriculture, l’alimentation et l’environnement Access content directly
Journal Articles Journal of Food Engineering Year : 2024

Impact of sugar reduction on the glass transition temperature and sorption isotherm of freeze-dried tomato powder

Abstract

The objective of this work was to improve the drying of tomato juices after identifying the main parameters that are responsible for sticking during drying. Glass transition temperature (Tg) which is one of the key parameter, depends on the juice composition, mainly sugar. In order to reduce sugar, centrifugation was applied to the juices. Tg was determined by differential scanning calorimetry (DSC) for freeze-dried tomato juice and tomato pellet conditioned at various water activity (aw) (0.1-0.5). The glass transition curve showed that Tg decreased with increasing of the moisture. Comparison of powders obtained by juice and pellet from centrifugation shows that the Tg of freeze-dried pellets is higher than that of juice at equal aw values. Adsorption isotherms of freezedried tomato juice and pellet were determined at 25 degrees C and a relative humidity (RH) of 0-98% using a dynamic technique. The data obtained were fitted to GAB model that best fitted the experimental data. The equilibrium moisture content (X) value of the freeze-dried pellets are lower and had the same value of 8% dry mass. X is lower because the pellet powders are less hygroscopic than tomato juice powders because of the reduction of soluble compounds by centrifugation, notably sugars. Reducing the product sugar content by centrifugation enables to raise Tg without using carriers and obtain less hygroscopic powders, which is advantageous for product storage.
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hal-04621630 , version 1 (24-06-2024)

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Robert Thierry Malomar, Caroline Garcia, Beatrice Gleize, Vanessa Jury, Emilie Korbel, et al.. Impact of sugar reduction on the glass transition temperature and sorption isotherm of freeze-dried tomato powder. Journal of Food Engineering, 2024, 380, ⟨10.1016/j.jfoodeng.2024.112137⟩. ⟨hal-04621630⟩
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