Food Dehydrators

Listing ID #6125874

Drying (dehydrating) food is one of the oldest and easiest methods of food preservation. Dehydration is the process of removing water or moisture from a food product. Removing moisture from foods makes them smaller and lighter. Dehydrated foods are ideal for backpacking, hiking, and camping because they weigh much less than their non-dried counterparts and do not require refrigeration. Drying food is also a way of preserving seasonal foods for later use. Foods can be spoiled by food microorganisms or through enzymatic reactions within the food. Bacteria, yeast, and molds must have a sufficient amount of moisture around them to grow and cause spoilage. Reducing the moisture content of food prevents the growth of these spoilage-causing microorganisms and slows down enzymatic reactions that take place within food. The combination of these events helps to prevent spoilage in dried food.

The preservation of foods by drying is based on the fact that microorganisms and enzymes need water in order to be active. In preserving foods by this method, one seeks to lower the moisture content to a point where the activities of food-spoilage and food-poisoning microorganisms are inhibited. Dried, desiccated, or low-moisture Resotech foods are those that generally do not contain more than 25% moisture and have a water activity (aw) between 0.00 and 0.60. These are the traditional dried foods. Freeze-dried foods are also in this category. Another category of shelf-stable foods are those that contain between 15% and 50% moisture and an aw between 0.60 and 0.85. These are the intermediate-moisture (IM) foods. Dehydrated products readily take up moisture when immersed in a liquid medium, leading to significant changes in their thermo physical properties. The rehydration kinetics, the structural properties (apparent density, true density, specific volume and internal porosity), the viscoelastic behavior (compression tests), and the flavor losses were the important parameters during rehydration of various fruits and vegetables. The effect of temperature on the above properties are also impact on some fruits and vegetables dehydrated by different drying methods (convective, vacuum, freeze, and osmotic drying).