Amélioration de la qualité de la tomate séchée par microondes assistés par air chaud avec pilotage de la puissance spécifique

Abstract : The aim of this study was to improve the quality of dried tomato by the use of microwaves combined to hot air (MOAC). The main point was to preserve the quality of dried tomato avoiding the appearance of black spots which often occur during microwaves heating which result from local overheating of the product when it becomes dry. Therefore, an MOAC drying system with ability of automatic control of the power density was developed under LabView®. After an initial study where the applied microwave power remained constant during the drying, a second MOAC drying strategy, with two different control modes, was implemented. This modes consisted to adjust the microwave power density to the remaining amount of water (actually the weight of the product). In the fist one, it is adjusted every second, while in the second, the power was adjusted only every 5 min. Therefore the ratio between the power applied and the weight of the product (i.e. the specific power) remained constant. All the process parameters, including the power applied and the product temperature and weight were recorded every second. The final product was characterized by performing measurements on color, texture, structure and residual lycopene content. In our initial study on MOAC drying performed at constant power (i.e. variable specific power), we have obtained dried tomatoes with hot spots and with a residual lycopene content lower than 50%. The tomatoes dried at constant specific power showed a better physical aspect and a higher nutritional quality, even compared to two commercial products from Italy and Ivory Coast. In addition, the structure of dried tomatoes observed by Scanning Electron Microscopy (SEM) allowed to explain changes in dried tomatoes texture. Chemically, the residual rate of lycopene in tomatoes dried at constant specific power ranged respectively between 64.78 and 55.63% for low power and air temperatures (3W/g-30 °C) and between 31.91 and 28.75% for high power and air temperatures (7W/g-50° C), while only 30.56 and 22.30% for commercial tomatoes from Italy and Ivory Coast.
Document type :
Theses
Complete list of metadatas

https://pastel.archives-ouvertes.fr/pastel-00771870
Contributor : Abes Star <>
Submitted on : Wednesday, January 9, 2013 - 3:12:13 PM
Last modification on : Monday, September 2, 2019 - 2:46:08 PM
Long-term archiving on : Wednesday, April 10, 2013 - 3:53:13 AM

File

KONE_Manuscrit_-_final.pdf
Version validated by the jury (STAR)

Identifiers

  • HAL Id : pastel-00771870, version 1

Citation

Kisselmina Kone. Amélioration de la qualité de la tomate séchée par microondes assistés par air chaud avec pilotage de la puissance spécifique. Economies et finances. AgroParisTech, 2011. Français. ⟨NNT : 2011AGPT0058⟩. ⟨pastel-00771870⟩

Share

Metrics

Record views

1283

Files downloads

10116