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Online optimisation of fruit drying based on drying curve identification

Nuninger, Walter and Catiau, Lucie and Montastruc, Ludovic Online optimisation of fruit drying based on drying curve identification. (2007) In: SFGP 2007, 9-11 Octobre 2007, Saint Etienne, France .

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Abstract

Drying optimisation is of great interest for food industry both in economic terms (energetic cost) and from an organoleptic point of view (product quality). Dryers are designed to extract the water out of the product while preserving its qualities of interest. Although both optimisation of the heat production system and the drying chamber can be considered separately, it is useful for the industry to be able to globally supervise the production system and reduce the drying time despite the local optimised technical solution already available. Required performances (qualities in terms of moisture rate, operating time…) can be achieved within a correct estimation of the fruit moisture in order to configure control set points. The methods suggested in this paper are based on thermodynamical knowledge on water exchange in order to achieve an online identification of the drying curve mathematical model using a set of known data at the current time. Such model can allow further prediction of drying duration and control adaptation but also the qualification of the original product that might differ from one production to another because of fruit maturity or origin for instance. In this paper, no prior knowledge of the raw material to dry is required (except part of process history) to perform model identification and selection (within quadratic programming, parametric estimation or interpolation under correct assumptions). Of course constraints as maximal temperature supported by the fruit and the dryer limitations should be taken into account to proceed to a two-step drying (pre-drying and drying at higher temperature) to achieve the performances. Despite the simplicity of the model, the proposed algorithms are sufficient to allow the detection of a change in the fruit structure due to the loss of water; that results in a modification of water activity. Although the application is made on a laboratory incubator with great limitation of the control, the method is to be transposable on any dryers of industrial scale with the advantage that it requires only a limited number of measurements.

Item Type:Conference or Workshop Item (Paper)
Additional Information:Acte de conférence de la collection en CDrom : Récents Progrès en Génie des Procédés – Numéro 96 – 2007 ISBN 2-910239-70-5, Ed. SFGP, Paris, France
Audience (conference):National conference proceedings
Uncontrolled Keywords:
Institution: Université de Toulouse > Institut National Polytechnique de Toulouse - INPT
Université de Toulouse > Université Paul Sabatier-Toulouse III - UPS
French research institutions > Centre National de la Recherche Scientifique - CNRS
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Deposited By: Ludovic MONTASTRUC

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