François Giroux

Osmotic treatments (OT) and problems related to the solution management

The implementation of osmotic treatments (OT) of plant or animal materials in concentrated solutions (called also dehydration-impregnation by soaking process, DIS) presents a critical factor due to the management of the concentrated sugar/salt solutions. In particular some process steps must be evaluated in order to assess economical, environmental and technological impacts of the process itself. In this paper the critical points of the solution management have been criticised taking into account the items related to the solution changes during the process, the possibility to restore or re-use the solution itself and the relationship between the food on-going to dehydration and the solution properties.

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.

Modeling of dewatering and impregnation soaking process (osmotic dehydration)

Abstract Partial dewatering and simultaneous solute impregnation can be obtained by immersion of food pieces in concentrated solutions. Recently, further understanding of cross mass transfer was achieved by experimental study and modelling on agar model gel foods.

Equipment design for osmotic treatments

Recent osmotic treatment (OT) applications make it necessary to develop specially designed items of equipment, particularly where a high level of dehydration is necessary. This paper defines the functions required by users of osmotic dehydration equipment and presents seventeen principles used to contact foods with a concentrated solution. It then compares the different technical solutions.

Mise au point d’un procédé combiné de déshydratation imprégnation par immersion et séchage de bananes (Musa acuminata groupe Cavendish)

Abstract Banana ( Musa acuminata group Cavendish ) treatment by the combined process of dewatering-impregnation soaking process (DISP) and drying was studied in the present work. Experiments were carried out in a laterally agitated vat. Bananas were cut into slices of 10 mm thickness before soaking and drying. A method of banana treatment was determined and consisted of soaking products in two successive sucrose baths with respective concentrations of 35°Brix and 70°Brix, acidified at 3.5 pH with ascorbic acid. The first bath, which contained 1% calcium chloride to ensure the firmness of the fruit, served also in blanching the fruit. This consisted of soaking the fruit in the solution initially heated at 85 °C and leaving them to dehydrate while cooling slowly to room temperature over a period of 24 h. The mass ratio of fruit to solution for this bath was 1:6. Dehydration in the second bath at 70°Brix was conducted with a fruit to solution ratio of 1:4 and at room temperature, for economic reasons and for the quality of final product. This second treatment was doubly important: there was an increase in the sugar content of the fruit and further water loss maintaining the banana slice shape during the final drying. It also conferred on final product a good mouth-texture (the final product was softer), a pleasant sweet taste and spread the banana aroma more widely. Treatment in two successive baths led to a weight reduction of 60.2% and a solute gain of 2%. Bananas then underwent a moderate drying at 40 °C for 72 h with an air relative humidity of less than 60%. The water content of the final product was 16.5% and its average water activity was 0.54±0.02 at 25 °C. The final product had an attractive colour and did not show any brown pigmentation.

Etude des parametres de controle et de commande du procede de deshydratation–impregnation par immersion, sur systeme probatoire automatise: application au traitement des pommes “Golden”

Abstract The work presented here is a study aiming at the control and checking of dewatering and impregnation soaking process (DISP). The studies are carried out using an automatic experimental system. Apples of the “Golden” variety are used exclusively. Two kinds of agitation system are studied; mechanical agitation using a vertical screw without an end, and hydraulic agitation. There is hardly any difference between the two kinds of agitation; parameter variations are almost the same. These results are compared with those obtained in agitated thermostated water-bath system and they show that mass transfers are better on the experimental system than with the water-bath system. Temperature influences were studied for the agitated thermostated water-bath system only. They show that the increase of temperature favours water loss and sugar intake. We have shown that during experiments with old syrup, only the conductivity of syrup is higher but kinetics of water loss, solute intake and weight reduction are not significantly affected.

Contribution to the Building of an Equipment Design Method in Developing Countries Using an Analysis of Traditional Pratices

In order to enhance efficiency of local design and manufacturing of smallscale equipment in Developing Countries, produced in the field of agriculture and food-processing, the authors have analyzed traditional practices of equipment designing and examined the strategy of the actors involved. Twenty-three equipment design histories have been analyzed in terms of organization and interaction between design actors. They outlined generally revolve around an individual design carried out by an alone person with mechanical engineering skills and a lack of analysis of the final user environment. The present work has been used to determine a new method of equipment design taking into account the socio-technical environment.

Socio-technical networks: a tool for integrating the maintenance dimension in the design of equipment for small food-processing units in Western Africa

In Burkina Faso, as in other Western African countries, maintenance in small food-processing units is carried out by several actors. These actors form an informal network and contribute to ensuring that equipment is operationally available in a more or less satisfactory manner. Our field studies have revealed how important informal networks are in the economic life of African countries, especially those in West Africa. This paper describes a formal method for representing and analysing sociotechnical maintenance networks and proposes its integration within the wider framework of the CESAM design method. Three types of equipment illustrate the above hypothesis. Lessons learned from the analysis of the representations have served as a basis for an improvement of the CESAM design methodology that ensure that, during the design phase, the maintenance aspects are reasonably tackled.