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 with most of the water removed (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.

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 water is required for rehydration.

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 for the emphasis placed on finding water – in some form – on Mars, prior to the arrival of the first astronauts.

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.

The dehydrated products may 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. 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 2 below.

Journal sample

Figure 2: A sample journal set-up, with explanatory additions, that may be used to record data from a food preference survey.

Analysis

  1. 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?
  2. Identify the foods which be best consumed “as is”, re-hydrated, or blended with other foods?

Extension Activities

  1. Dehydration is only one method of preserving food. Investigate other methods by which the "shelf-life" of food can be extended.
  2. In these activities we have considered only food crops that can be easily grown. Use Canada's Food Guide and identify the major food groups have been neglected in our study.
  3. 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.