Activity 2: Food Storage/Dehydration

Objective

To investigate the effects of dehydration on the taste of food.

Preserved Foods

Many foods will last much longer if they have had most of the water removed from them. The process whereby water is removed is called dehydration. Foods in which the water component has been removed are called dehydrated foods.

For long duration trips dehydrated foods are great. Some dehydrated foods can be eaten in their dehydrated state, others are best if water is available to re-hydrate them before they are eaten. Dehydrated foods are much lighter to carry since the water has been removed. Backpackers and canoe trippers love dehydrated foods since they are lighter to carry and also take up less space in a backpack.

However, for long duration space missions the water requirement poses a problem. While we want the food we take into space to be as light as possible, and as compact as possible, the advantages are totally lost because we have to take the water along to re-hydrate them.

Of course there is still the advantage that dehydrated food stores much longer than fresh foods. (But are they as appetizing?)

The need for water to re-hydrate preserved dehydrated foods is one of the major reasons that we must find a source of water (possibly as ice or permafrost-like frozen ground water) somewhere on Mars before we plan to land there.

Class Survey

Using the same Food Evaluation Scale as in Activity 1, it is interesting to perform a preference evaluation of the hydrated vs dehydrated food listed on the Food Preference Chart for Dehydrated Food in the Resources section that follows. OPTIONAL: The dehydrated products can be purchased quite inexpensively at bulk food stores in small quantities. You may want to bring several selections into the classroom for the students to sample prior to doing the preference survey. Please refer to your student information data to check for food allergies first.

Students should add a new entry for this survey in the journals they set up for Activity 1. See Figure 3 below.

Journal sample

Figure 3: A sample journal set-up, with explanatory additions, that may be used to record data from a food preference survey.

Analysis

Of the items selected above could you determine if, in general, dehydrated foods taste better, taste worse, or whether there is no general rule for the taste difference?
Which of these do you think would be best eaten as is, re-hydrated, or blended with other foods?

Extension Activities

Dehydration is only one method of preserving food. Investigate other methods by which the "shelf-life" of food can be extended.
In these activities we have considered only food which can be easily grown. Use Canada's Food Guide and determine which major food groups have been neglected in our study.
Using Canada's Food Guide (a basic version is given in the Resources section that follows) create a menu for one day that will provide a well balanced diet for an adult astronaut. Consult the Eating Well with Canada's Food Guide web site for a more detailed explanation of the food guide. You might also want to visit the Canadian Astronaut Missions section of the Canadian Space Agency web site. You will be able to access actual menus from completed space missions.

Tomatosphere is sponsored by Agriculture and Agri-Food Canada, the Canadian Space Agency, Heinz Canada Ltd, HeinzSeed, Ontario Centres of Excellence, Stokes Seeds and the University of Guelph.