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MICROCALORIMETRIC STUDY OF THE FREEZE-DRYING OF FRUIT JUICES.

ETUDE MICROCALORIMETRIQUE DE LA LYOPHILISATION DES JUS DE FRUITS.

Author(s) : SIMATOS D.

Type of article: Periodical article

Summary

MICROCALORIMETRIC CELLS, SUITABLE FOR THE CALORIMETER WITH CAPACITY COMPENSATION CPC 600, HAVE BEEN DEVELOPED FOR NEW CALORIMETRIC MEASUREMENTS OF HEAT TRANSFER DURING FREEZE-DRYING. WITH ONE OF THEM ONE CAN DIRECTLY MEASURE THE SUBLIMATION SPEED UNDER ISOTHERMAL CONDITIONS. ANOTHER ONE FACILITATES THE MEASUREMENT OF MASS TRANSFER THROUGH THE POROUS LAYER AS A FUNCTION OF THE IMPOSED STRUCTURAL CHANGES. USE HAS BEEN MADE FOR ANALYSING THE CONDITIONS WHICH DETERMINE THE COLLAPSE OF THE STRUCTURE DURING THE FREEZE-DRYING OF SUCROSE SOLUTIONS. THIS PHENOMENON AND THE ACCOMPANYING PHYSICAL CHANGES HAVE ALSO BEEN STUDIED BY FREEZE DRYING UNDER THE MICROSCOPE -THERMAL AND ENTHALPIC DIFFERENTIAL ANALYSIS -DIFFRACTION OF X-RAYS -RHEOLOGY -PARAMAGNETIC ELECTRONIC RESONANCE. A METHOD HAS BEEN DEVELOPED BY WHICH MANY PRODUCTS CAN BE CLASSIFIED ACCORDING TO THEIR RESISTANCE TO COLLAPSE UNDER SIGNIFICANT INDUSTRIAL FREEZE-DRYING ABILITY OF VARIOUS RASPBERRY JUICES HAS BEEN FOUND. THE RESISTANCE TO COLLAPSE OF A MODEL SOLUTION INCREASES WITH THE INCREASE OF THE RELATIVE CONCENTRATION OF THE CONSTITUENTS IN THE FOLLOWING ORDER: CITRIC ACID -FRUCTOSE -GLUCOSE -SUCROSE. THE RESISTANCE CAN BE INCREASED BY SMALL CONCENTRATIONS OF POLYMERS (PECTINS -PROTEINS) THE PHYSICAL AND CHEMICAL PROPERTIES OF THESE POLYMERS ARE PLAYING AN IMPORTANT PART. (Bull. CNRS, FR., 81-401-1021.

Details

  • Original title: ETUDE MICROCALORIMETRIQUE DE LA LYOPHILISATION DES JUS DE FRUITS.
  • Record ID : 1981-1382
  • Languages: French
  • Source: DGRST - 76.7.0077; 19 p.; ref.
  • Publication date: 1980

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