Why drying is effective as a method of food preservation

If you are new to drying, start with a few of the easiest foods to dry: berries, banana slices, tomato slices, chopped onions, oven jerky, and smoked salmon. Trays used for drying foods in an oven or other methods than a food dehydrator need to be of a food-safe screen material such as plastic preferably polypropylene , stainless steel, Teflon or Teflon coated fiberglass, or wood.

An economical solution is to stretch cheesecloth or natural muslin over an oven or cake rack or a wood frame, and attach it with masking tape, paper clips, or clothespins. For a more permanent, but more costly option, have window screens made at a hardware store and use them for drying. Avoid materials which can leach harmful chemicals, darken the food, or melt at drying temperatures.

These materials include:. After oven drying a few foods, if you want to continue to use the drying method, consider investing in an electric food dehydrator. A food-dehydrating appliance has few weather dependencies, can consistently produce a quality product, and is less prone to inconsistency or other problems when drying foods. This makes it easier than most other methods. A good food dehydrator provides variable temperature control and good air circulation. Basic models have limited temperature ranges, vertical airflow, single-wall construction, and limited drying capacities.

Therefore, you may dry foods until pliable, especially if you want to use them as a snack food. If you want to store dried food longer or use it to grind to a powder such as tomatoes to make sauce , then you want them to be crisp and brittle. Less-dry products have considerably shorter shelf life—from 2 weeks to 2 months. Very dry foods, if properly stored, may last several months. Whether pliable or crisp, condition all foods at the end of the drying process.

Alternatively, you may store partially dried or unconditioned foods in the freezer. Individual pieces of food dry at different rates; some pieces will have more moisture than others.

If there is too much moisture left in a few pieces, they can grow mold and contaminate the entire batch. Salt is effective as a preservative because it reduces the water activity of foods.

The water activity of a food is the amount of unbound water available for microbial growth and chemical reactions. Salt is used to preserve beef jerky by keeping it dry, and it prevents butter from spoiling by drawing water out, leaving just the fat.

Salt kills microbes. High salt is toxic to most not all microbes because of the effect of osmolarity, or water pressure. Sugar may also provide an indirect form of preservation by serving to accelerate accumulation of antimicrobial compounds from the growth of certain other organisms. The science of using vinegar for food preservation is simple. The acetic acid contained in the vinegar increases the acidity of the vegetables, killing off any microorganisms and effectively preserving the veggies by preventing spoilage.

Sugar helps preserve the color, texture and flavor of the food. The sugar in jams and jellies helps the gel to form, and increases the flavor. When large amounts of sugar are used in a recipe, the sugar also acts as a preservative by inhibiting microbial activity; thus, recipes should not be modified or adapted.

Vinegar is used in all sorts of food preservation methods. It has a few key properties that make it ideal at slowing or stopping food from spoiling for long periods. It is primarily the pH or acidity of vinegar that inhibits bacterial growth and this process is most commonly called pickling.

Vinegar is made from fermentation of sugar and water solutions and it acts as an effective natural preservative. The acetic acid present in vinegar kills microbes and inhibits food spoilage. Adding common vinegar in your food can not only preserve foods but also help enhance their taste. Types of Drying. Food Preservation and Storage You are currently using guest access Log in.

Advantages of Drying Food Preservation Storage. Advantages of Drying Preservation is the main reason but not the only reason for dehydrating foods. Factors in control of drying: Various factors affecting rate of drying in a fresh produce include the following: Composition of raw materials: Foods containing high amount of sugar or other solutes dry slowly. Size, shape and arrangement of stacking of produce: Greater the surface area greater is the rate of drying.

Temperature as well as humidity and velocity of air: Greater is the temperature differential between the product and the drying medium faster the product dries. Lower the humidity of environment the faster the drying will be.