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.

Figure 2: 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?
- Identify the foods which be best consumed “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 crops that can be easily grown. Use Canada's Food Guide and identify the 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.
How to Feed a Martian
- Table of Contents
- Background Information and Notes
- Curriculum Expectations
- Activity 1: Selecting Foods
- Activity 2: Food Storage/Dehydration
- Cross-curricular Extension Activity
- Assessment
- Storage Times for Crops
- Crop Characteristics
- Food Preference Chart for Dehydrated Food
- Canada's Food Guide (Simplified Version)
- Links
Teacher Resources
- NEW Seed Treatment for 2012
- NEW Priming
- Seed Treatment for 2011
- Growing Spheres
- Energy Diet Challenge
- Tomatosphere Project Overview
- Tips 'n' Tricks
- 2011 Teachers' Guide
- PDF Resources [Printable charts from the Teachers' Guide]
- Four Optional Units
- Biological Life Support Systems
- Tomatosphere Supplies
- Tomatoes in Space [Video]
- Heinz Tomato Breeding Program
- International Space Station
- Astronaut Mike Fincke talks about the importance of Tomatosphere [Video]
- CSA Teachers' Conference
- CSA Teacher Resources
- Exploring Mars
- Mars Environment
- Seed Starting Guidelines

