The concept of water activity is important to food preservation. When water activity is less than 0.6, almost all microbes, including bacteria, molds, and yeasts, stop growing. Vegetables are usually dried even further, to water activity of 0.3 or 0.2, for quality and storage. Virtual Labs – Controlling Water Activity in Food explores a traditional method of preserving corn by drying. In this virtual laboratory, learners test water activity levels of dried corn and explore how they change under three different storage environments. The interactive animation guides users through the theory and practice of sampling a food product, using a water activity meter, and setting up replicates, to build familiarity with concepts and procedures used in real food science labs. Before beginning this lab, it may be useful to complete Virtual Labs – Understanding Water Activity.

Testing the pH of a substance (how acidic or basic it is) is a basic lab test and provides a important piece of information for natural science investigations. In food science, the pH of a substance – how acidic or basic it is – is key to how it functions in food recipes. This module introduces users to the pH scale and its uses in food science. Then, users learn how to use the pH meter, and calibrate it by measuring solutions of standard value. Virtual Labs – the pH Scale & Meter Calibration familiarizes the user with food science lab equipment and teaches standard techniques for this specific procedure. The interactive animation guides the user through theory and practice of using the pH scale and pH measurement, so they will have familiarity with the equipment and procedures when encountered in a real lab.

Moist foods – like fresh fruit or raw meat – often have high water activity and spoil quickly. But some foods that seem moist – like jam or pepperoni – don’t spoil as quickly. Why is this? All living things need water to survive. Enzymes and chemical reactions also require water. If water activity is less than 0.6, almost all microbes, including bacteria, molds, and yeasts, stop growing. This means that food can be preserved against spoilage by lowering its water activity – whether by evaporating water away or binding it up. Virtual Labs – Understanding Water Activity familiarizes the user with food science lab equipment and standard techniques for measuring water activity. The interactive animation guides the user through both theory and practice, preparing them for experiences in a real lab. Complete this lab first, then follow up with Virtual Labs – Controlling Water Activity.