Application of the differential scanning calorimetry method in the study of the tomato fruits drying process
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Structural changes in the process of heating fresh fruit, sundried fruits and powder obtained from the dried tomato fruits were studied by differential scanning calorimetry method application. The kinetics of the shredded fruits in the dryer proves the prospects for using convective drying, which is performed for 295 minutes. The kinetic coefficients of drying and critical moisture content in the crushed fruits of tomato were determined. The kinetic coefficients were determined by the graphicalanalytical method: a = 0.839, ln(α) = 1.3 and α (1 s–1 ) = 0.262. It was determined that the critical maximum moisture content for drying the shredded fruits of tomatoes is 1.503% mm–1 , after what the process of combustion of vegetable tissue begins. The application of the differential scanning calorimetry (DSC) method allowed the fuller study of the mechanism of drying the fruits of tomato in different condition: fresh, sundried and dried. It was determined that the greatest amount of energy is consumed to remove free moisture (1,993 J g–1 ) from the fresh tomatoes. At the same time, when being cooled, crystallization in plant tissue occurs with the release of energy in the amount of 0.03922 J g –1 . When drying the previously sun-dried tomatoes the process of moisture removal and the partial decomposition of the compounds that are unstable to temperature is completed. At the same time, at the 129.61 °C temperature in the powder obtained from the fruits of tomatoes, melting of carbohydrates and other compounds occurred. Thus, this confirms the need to observe the normalized value of the mass fraction of moisture in the powders in the process of their packaging, storage and use. The basic technological system of production of powder from dried fruits of tomatoes is offered.