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Monitoring Freeze-Drying by Low Resolution Pulse NMR: Determination of Sublimation Endpoint |
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| Authors: | J.P. MONTEIRO MARQUES C. LE LOCH E. WOLFF D.N. RUTLEDGE |
| Affiliation: | Authors Monteiro Marques and Rutledge are with Lab. Chimie Analytique, Institut National Agronomique 16, rue Claude Bernard, F 75231 Paris Cedex 05, France.;Authors Loch and Wolff are with I.N.R.A. Lab. Génie des Procédés Biotechnologiques Agro-Alimentaires, I.N.A.-P.G., F 78850 Thiverval-Grignon, France. |
| Abstract: | An NMR method was developed for detection of the sublimation period endpoint during the freeze-drying of potato pieces. Longitudinal (T1 and transverse (T2) relaxation times were estimated using rapid NMR methods. Samples were immediately examined to determine presence of a frozen core. The plot of T1 vs T2 showed an abrupt increase at a point corresponding to the complete elimination of the frozen core. Similar Tj vs T2 curves were observed when monitoring freeze-drying of a single potato piece inside the NMR probe-head. The detection of an anomalous freeze-drying is possible by monitoring the T1 the T2 or the free induction decay signal. |
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