Stéphane Guilbert

Simultaneous water and solute transport in shrinking media. Part 1 : Application to dewatering and impregnation soaking process analysis (osmotic dehydration)

ABSTRACT Agar model gel cubes, with initial low solute content, were soaked in higher concentration solutions. The influence of the concentration and molecular weight of the solute in the soaking solution, the temperature. the agar and solute content of the model food on water loss and solute gain rates were observed. The achievement of a prevailing dewatering effect with only marginal solute pick-up proved to be related to a inverse relationship between the cross-flows of water and solute, reinforced by shrinkage. As a preliminary to further modelling, reasonable assumptions were drawn from experimental result analysis.

Simultaneous water and solute transport in shrinking media. Part 2 : A compartmental model for dewatering and impregnation soaking processes

ABSTRACT A simple compartmental model of simultaneous water and solute transport was developed on agar gel cubes, for particular situations in which high water loss is accompanied by shrinkage and flux interaction. The model provided a good fit for the different situations tested, and proved to behave adequately in a wider application field. Furthermore, it made it possible to obtain a simulation of the evolution of the solute contents in both compartments which was consistent with the previous studies.

SIMULTANEOUS WATER AND SOLUTE TRANSPORT IN SHRINKING MEDIA - PART 3: A TENTATIVE ANALYSIS OF SPATIAL DISTRIBUTION OF IMPREGNATING SOLUTE IN MODEL GEL

ABSTRACT Agar agar model gel cubes, with initial low sucrose content, were soaked in 40% and 60% sucrose solutions. In both situations, sucrose profiles were obtained by slicing and HPLC analysis. Results provided an experimental validation for the concentrated surface layer assumption and the compartmental model of mass transfer, described in Parts 1 and 2. respectively.

Sucrose and osmotic dehydration

The osmotic dehydration process, previously reviewed by Ponting et al. (1966), Le Maguer (1988), and Raoult-Wack et al. (1992), consists of soaking moisture-rich foods in concentrated solution, which creates two cross mass transfers (Ponting et al., 1966; Karel, 1975; Hawkes and Flink, 1978).

Recent Advances in Dewatering and Impregnation Soaking Processes

Simultaneous dewatering and impregnation can be achieved through soaking of foodstuff pieces in highly concentrated solutions This is the so-called “Dewatering and Impregnation Soaking Process”, or briefly DISP. After a brief recall of general process characteristics, recent advances in mass transfer analysis are presented that more specially concern model foods (agar gel cubes) and fruit pieces (frozen and fresh apple) immersed in sugar juices. Consequences upon the improvement of traditional techniques (osmotic dehydration, direct formulation ...) are discussed. As a correlation, original technological applications and new processing ways are hinted at.