Definition of Preservation Methods

Canning – Processing food in airtight containers for preservation. This process uses containers made of aluminum, tin, or glass. Hot food is packed into the container and sealed either under pressure or a boiling water bath.

Dehydration – Simply put, removing the water from food products for preservation. In early history, food was thinly sliced and placed on flat rocks in the sun to dry. Later, as people became less nomadic, racks were built for hanging long, thin slices of meat, think of jerky.

Commercially purchased dehydrators utilize mesh screens for racks, and electric fans to continually pull air across the food. The mesh screens allow the air to reach both sides of the food, while the fan speeds the process. Bacteria must have moisture to grow and multiply. Eliminating the moisture in food eliminates the bacteria that cause spoilage.

Example of a dehydrator available can be found at amazon.com: Waring DHR30 Professional Dehydrator

Dry-Salting – This process draws moisture from food using a great deal of salt. This moisture dissolves the salt into brine, which inhibits the growth of micro-organisms. Only small or thin foods can be preserved this way. Small fish are often preserved in this manner. Done properly, fish can then be refrigerated for as long as two years.

Fermentation – Although very similar to brining, fermentation requires very exacting measurements of salt, vinegar, and temperature. Caused by benign micro-organisms interacting with salt brine, they convert vegetable sugars into acids.

Dill pickles are made in this method, which can take three to six weeks to prepare. If processed (using pressure canning) following the fermentation period, these foods can be kept indefinitely.

Freezing – Placing protected food in an environment that keeps it at 0oF [-18oC]. This method of food preservation is the easiest. It also keeps most foods closest to their original form. Not including the original investment in the actual appliance, freezing is a very economical way of preserving food. A quick blanch to halt enzyme production, and protection from the frigid, dry air is all that is required in preparation.

Jelling – Preserving with sugar seems to be a contradiction in terms. It is true that micro-organisms thrive on weak sugar solution. In a strong concentration sugar has a dehydrating effect, similar to that of salt, inhibiting the development of micro-organisms.

When pectin is added, the fruit being preserved gels, or jellies. Jellies, jams, marmalades, and preserves are all made with similar processes. They are then put in sterile containers, sealed with paraffin, and stored in a cool, dry environment. Only fruit butters, cheeses, and preserves of whole fruit pieces should instead be water bath processed.

Irradiation – Although not available to the in-home food preserver, this method of preservation is being utilized more frequently as the technology improves. In its simplest definition, food is exposed to a dose of ionizing radiation.

The dose of radiation and time of exposure varies. This process works by damaging the microbe’s DNA in such a way as it is unable to repair it. When this occurs, the microbe cannot mature, nor can it process cell division, its method of reproduction. If the dosage is high enough, the microbe is killed outright.

Although the food itself cannot become radioactive (the particles transmitting the radiation are not themselves radioactive), and this method of food preservation is used in more than fifty countries worldwide, because of its association with the nuclear industry, some people in the USA still find food irradiation to be controversial.

Pickling – Also called brining, this method infuses wonderful flavors into the food being preserved. Brine is made, usually containing salt, sugar, and vinegar. Herbs or other flavoring ingredients are added to the brine and then heated.

The food being preserved is then immersed in the brine. Ice can be used to prevent any fermentation from occurring. Depending on the food being preserved and the amount of flavor to be infused, brining times can be as little as fifteen minutes or as long as months.

Smoking – In the same way dehydration preserves meats, smoking also depletes it of moisture. However, the aroma of the wood smoke is absorbed by the meat, flavoring it in a way that cannot be otherwise duplicated.

From lightly scented maple wood to the heady flavors derived from the smoke of oak or hickory, the choice of wood is a great consideration for the end product desired. Smoking times can vary from just a few hours to a week or more. Meats preserved this way do require refrigeration. Smoking may also be used in conjunction with salting or brining.