Early Methods of Food Preservation
Before the days of man-made refrigeration and electric freezers, food preservation was limited to a handful of age-old methods. Without the input of electrical technologies, people were limited to the preservation methods available to them in their immediate surroundings. For example, where there was no natural snow or ice, such as in the southern colonies, freezing, as a method of preservation was not an option. Here below is a list of the six basic forms of preservation used in storing food.
I. Desiccation (dehydration)
II. Heating
III. Freezing
IV. Fermentation
V. Chemical Preservation (naturally occurring chemicals)
VI. Freeze drying
Desiccation (dehydration)
Desiccation is simply the process of removing the water content of a food item. By preserving food using this method, food can be kept for a long time without making any compromises regarding the nutritional value of the food. Dehydration of food also drastically cuts down of weight, given the fact that most food contains between 75-90% water, making this method ideal for long travels where fresh food is not available and weight is a critical issue. Simple dehydration is most commonly applied to fruits, vegetables, and fungi, while meats are usually dried in conjunction with a chemical preservative of some sort to further ward off bacteria and extend shelf life. Low heats, either generated by the sun, warm oven, or fire are the most common ways of drying goods, with an obvious dependence on location. The sun drying methods probably wouldn't be the best choice in the Northwest.Heating
Applying high heat to food has proven to be an effective method of preserving due to the sterilization that occurs. By raising food items to a high enough temperature and then sealed, bacteria is killed off leaving a sterile product. Compared to its counterparts, heat preservation did no really strike popularity until the development of pottery and cooking vessels. Nowadays, with the advancement in cookware, pressure-cooking is a widely used, usually more effective sterilization method, speaking in particular reference to canning/jarring. Sterilization via pressure cookers works by placing the food item in a can/jar that is sealed and then place in a large, heavy-duty pot filled with a few inches of water. A lid, which contains a rubber ring to seal the pot, is placed on top and tightened down. With this method, heat generated in the pot is not released but instead sealed on the pot, creating a pressurized environment which is usually kept t around 20 to 30 pounds. Under pressure, the contents inside can be raised to a much higher heat that when not pressurized, making the sterilization process even more safe.Freezing
This method is pretty self-explanatory. By lowering food temperature below the freezing level, bacteria and molds cannot thrive, thus keeping the food preserved almost indefinitely. This has to probably be the oldest farm of preservation for people living in cold climates around the world.Fermentation
Fermentation is the slow decomposition process of organic substances induced by micro-organisms, or by complex nitrogenous substances (enzymes) of plant or animal origin (Walker, 1988). Cheeses and alcoholic beverages have long been prized for their retention of nutrients, longer shelf life, and portability, not to mention the enjoyment of consumption. The fermentation of certain liquids is especially important in arid climates where water is scarce. This method proves to be a practical and efficient way of preserving, especially in developing countries (like colonial America) and remote areas of the globe.
Chemical Preservation
Chemical preservation involves introducing a chemical to a food item in order to suppress the ability of bacterial growth. As mentioned before, this type of preservation is most commonly associated in conjunction with dehydration. Contrary to popular view, food additives are not a new phenomena, maybe just the vast quantity is. Salting, smoking, and spicing were the three most common forms of chemical preservation. Meats cured with salt as well as smoked meats were especially important due to the rapid decay of meat in practically any environment that is above the freezing level. Smoking introduces the antioxidants butylates hydroxyanisole and butyl gallate in large amounts which inhibits bacteria growth. Spices have a similar quality, being rich in antioxidents as well as bactericides (substances that kill bacteria.)
Freeze drying
Another method that has been used for thousands of years, yet thought to be a modern innovation is freeze-drying. This is not a widespread method due to its environmental pre-requisites, yet where conditions are right proves to be a very effective method. Natives of South America living in he Andes have found out by taking potatoes to a high point in the mountains where the atmospheric pressure is low, the potato can be sliced and crushed and then spread out on rocks while the combination of freezing air and low pressure take over and freeze-dry the potatoes.
