EVITHERM WORK 2004 : FOOD

1. EVITHERM WORK 2004 : FOOD A. RAEMY Nestlé Research Centre Nestec LTD CH- 1000 Lausanne 26 Switzerland According to the request of Joachim Fischer, PTB, Berlin

2. Evitherm 2004: data main requirements (1) • Specific heats of foods and some non food materials (mainly packaging and process materials such as stainless steel, copper, polymers,…) • Glass transition temperatures which are abrupt changes in specific heats • Thermal conductivity • Basics of thermometry NRC/FS - ARY

3. Evitherm 2004: data main requirements (2) • Phase transition (melting,…) temperatures • Reaction (oxidation, Maillard,…) onset temperatures • Transition and reaction enthalpy values • Enthalpies normed at –60°C • Data in relation with process safety (self-ignition temperatures under specific conditions,…) NRC/FS - ARY

4. Evitherm 2004: data main requirements (3) • Information has to be presented as: - tables - graphs - phase diagrams • Some formulas are necessary: - Q = m c ΔT - Fourier equation NRC/FS - ARY

5. Evitherm 2004: industrial associations in Europe • Caobisco, Brussels, Belgium • ASIC, Paris, France • Biscuit, Cake, Chocolate & Confectionery, London, UK • ILSI (Int. Life Sciences Institute) Europe, Brussels, Belgium • Campden and Chorleywood Food Research Association, Chipping Campden, UK • Leatherhead Food International, Leatherhead, UK • IVLV ( Industrievereinigung für Lebensmitteltechnologie und Verpackung) Munich, Germany • PIRA, Packaging Research, Leatherhead, UK NRC/FS - ARY

6. Evitherm 2004: trade publications • Commercial publications such as: - Lebensmittel Technologie (CH) - Der Lebensmittelbrief (GE) - Lebensmittel-Industrie (CH) • Bulletins from INRA, ENSIA, Leatherhead, FSTA, Campden and Chorleywood • Scientific journals such as: - J. of Food Engineering - Science des Aliments NRC/FS - ARY

7. Evitherm 2004: contacts outside • Anita Mikkonen, VTT Biotekniikka, Finland • Philip Barlow, National University of Singapore, Singapore • Douglas Goff, University of Guelf, Canada • Lebert Grierson, The University of the West Indies, Trinidad and Tobago NRC/FS - ARY

8. Evitherm 2004: network of contacts • Michel Ollivon, CNRS Chatenay-Malabry, France • Perla Relkin, ENSIA, Massy, France • Yrjö Roos, University College Cork, Ireland • Alberto Schiraldi, DISTAM, Milan, Italy • Danièle Clausse, UT Compiègne, France • Bertrand Roduit, AKTS, Sierre, Switzerland NRC/FS - ARY

9. Evitherm 2004: food businesses • Coffee: Nestlé, Kraft, Procter and Gamble,… • Oil and fat: Unilever • Tea: Lipton, Nestlé • Dairy: Danone, Nestlé, Milupa • Fish: Findus • Additives, emulsifiers: Danisco,… NRC/FS - ARY

10. Evitherm 2004: special remarks • It is difficult to have scientific contacts with small food companies • To distribute thermal information in small companies, the best persons would be: - Pierre Le Parlouër, Thermal Consulting, Caluire (F) - dedicated small companies - interested university professors NRC/FS - ARY

11. First approach: Specific heat (Cp) of foods Theoretical calculations Experimental determination Literature

12. Evitherm 2004: Specific heat Q = m c  T [Q] = J or W s [m] = g (or kg) [c] = J / g °C (or J/kg °C)  T = °C or K • General formula is: NRC/FS - ARY

13. Evitherm 2004: Specific heat • Theoretical calculation Food composition has to be known. Specific heat at ambient temperature of the food is obtained by proportional addition of the specific heat of each food constituent (water, carbohydrate, lipid, protein, ashes). NRC/FS - ARY

14. Evitherm-2004: Specific heat • Theoretical calculation Specific heat of food constituents [1] - For water: 4.18 J/g • For carbohydrate: 1.42 J/g • For lipid: 1.67 J/g (somewhat low) • For protein: 1.55 J/g • For ashes: 0.84 J/g • For ice: 2.11 J/g [1] V. Gekkas, Transport phenomena of foods and biological materials, CRC Press, Boca Raton,1992. NRC/FS - ARY

15. Evitherm 2004: Specific heat • Remarks - Specific heats of solids increase with increasing temperatureV. Gekas gives the caracteristic parameters of a quadratic equation describing this effect - Specific heat of water does practically not change between 0°C and 100°C - Specific heat depends strongly on the water content of the considered product - Some non-food specific heat values are also of interest (copper, stainless steel, aluminium,…). NRC/FS - ARY

16. Evitherm 2004: Specific heat • Experimental determination Calorimetric or DSC measurements allow to determine food specific heats at the temperature of interest. • Normally 3 measurements are necessary: • Reference material, usually synthetic sapphire • Empty cell • Sample cell NRC/FS - ARY

17. Evitherm 2004: Specific heat NRC/FS - ARY

18. Evitherm 2004: Specific heat • Formula is: where m1 isthe mass of the standard substance, m2 is the sample mass, C1 is the specific heat of the standard substance, and Q0, Q1 and Q2 are the required heat quantities for the empty cell, the standard substance and the sample, respectively. Remark: modern instrumentation has quicker methods but this is the most precise. NRC/FS - ARY

19. Evitherm 2004: Specific heat • Remarks: • Specific heat is generally determined at temperatures where the sample present no phase transitions • Glass transition phenomena are sometimes presented in the specific heat determination • Thermal conductivity is often found in the literature indicating specific heat. NRC/FS - ARY

20. Evitherm 2004: Specific heat • Literature on specific heat of foods [1] N. N. Mohsenin, Thermal properties of food and agricultural materials, Gordon and Breach, New York, 1980. [2] M. Pyda, Conformational Contribution to the Heat Capacity of the Starch and Water System, J. of Polymer Science:Part B: Polymer Physics, 39 (2001) 3038-3054. [3] A. Raemy and P. Lambelet, A calorimetric study of self-heating in coffee and chicory, J. Food Technology 17 (1982) 451-460. NRC/FS - ARY

21. Evitherm 2004: Specific heat THANK YOU FOR YOUR ATTENTION NRC/FS - ARY