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Temperature control at the wall in ohmic heater for dairy products

Identification

Key words Ohmic heating, fouling, dairy product, wall effect, surface temperature, laminar flow, cooling system, coolant
Latest version 2013/09/05
Completed by INRA - IATE

How does it work?

Primary objective Offering a heating treatment process with reduced damage to neither the dairy product nor the device.
Working principle Introduction:

Conventional thermal treatment techniques use indirect heat exchanges that generate wall phenomena with harmful effects (fouling, strong protein denaturation, generation of neo-formed contaminants, etc.). Ohmic heating is a volumetric, continuous and direct heating technique. Yet, the laminar flow through the treatment duct generates a speed gradient: the food product heating is slower at contact with the duct side, and faster at the centre of the duct. Consequently, the product on the sides stays longer in the pipe, and with the same energy input, it leads to an excessive heating, possibly causing damages: alteration of product qualities and fouling of the duct. (1,2,3)

New principle:

This new ohmic heater uses a temperature control sensor and a cooling system to have an equal temperature at every point of the flowing product. The cooling system uses a circulating fluid. (5)

Images
Additional effects
  • Organoleptic qualities of the product are not or hardly damaged, due to the very short duration of heating.
  • Limited protein denaturation due to temperature control at the wall.
  • Low generation of neo-formed contaminants
  • Prevention of fouling.
  • Increased production time.
  • Energy efficiency over 97%.
  • Very low heat emission; possible use in “low temperature areas”, e.g cold room in dairy industries.
Important process parameters Temperature retro-control
Important product parameters electrical conductivity, food composition

What can it be used for?

Products Homogeneous and heterogeneous dairy products.

Only liquid or viscous products

Operations Pasteurisation, sterilisation
Solutions for short comings Degradation of product qualities with conventional heating processes (pasteurisation, sterilisation)

What can it NOT be used for?

Products
  • Non pumpable products (solids for example)
  • Less interest on non-fouling products
Operations Non thermal operations
Other limitations not known
Risks or hazards not known

Implementation

Maturity The technology is available as pilot development equipment available for external users:

UHT pilot plant (100 L/h), R&D trials assistance, testing laboratories (Polytech Montpellier).

It is also purchasable at industrial or pilot scale.

Modularity /Implementation The technology requires a specific device which can be set up inside an existing line (continuous process).
Consumer aspects Not known
Legal aspects A French patent has been registered FR 2 863 829 – A1 (5)

Please check local legislation.

Environmental aspects
  • Energy efficiency over 97%
  • Very low heat emission

Further Information

Institutes UMII - Polytech
Companies GEA Niro, Emmepiemme
References (1) Bansai B. and Chen X.D. 2006. Effect of temperature and power frequency on milk fouling in an ohmic heater. Food and Bioproducts Processing, 84:4, pp. 286-291.

(2) Stancl J. and Zitny R. 2009. Milk fouling at direct ohmic heating. Journal of Food Engineering, 99:4, pp. 437-444.

(3) Ayadi M. A., Bouvier L., Chopard, F., Berthou M. and Leuliet J. C. 2003. Heat treatment improvement of dairy products via ohmic heating process: Thermal and hydrodynamic effect on fouling. In P. Watkinson, H. Muller-Steinhagen, & M. R. Malayeri (Eds.), The proceedings of the engineering conference international (ECI): Heat exchanger fouling and cleaning-fundamentals and applications

(4) Simpson D.P. and Stirling R., 1984. Apparatus for heating electrically conductive flowable media. US patent (not valid since 2001): US 4 434 357 A

(5) Beaucour P., Faydi-Bernadi E., Ponchard-Brutel A., Courel M., Gardin H., and Pain J.P., 2005. Procédé de traitement thermique continu de fluide et dispositive pour la mise en œuvre de ce procédé. French patent: FR 2863829 – A1

Temperature retro-control electrical conductivity, food composition Heaters 2.2.2 physical stabilizing other Interview with the researcher of Polytech Montpellier : Pr. Jean-Pierre Pain (jppain@univ-montp2.fr) WikiSysop :Template:Review document :Template:Review status



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Created by Hte inra on 29 June 2012, at 14:48