Food Preservation
Much of the information below is from Wikipedia, Kansas Historical Society, and the National Center for Home Food Preservation

Food preservation has been an essential activity throughout history. The very cycle of the seasons creates periods of shortage and abundance of different foods at different points of the year. This problem was only worsened with the development of agriculture as people sacrificed their mobility and came to rely on fewer sources of food, each with its own cycle of growing season. Only through human effort and ingenuity has it become possible to obtain some of these foods throughout the year.

Although some food may be damaged by chemical changes such as oxidation, most food is destroyed in storage by spoilage cause by living organisms such as molds, bacteria, and yeast. Food preservation techniques, therefore, depend upon killing or inhibiting the growth of these microorganisms.

Many of our most common means for preserving food have been with us since the beginning of history and can be found distributed in many different locations. Drying, pickling, fermenting, and smoking have all been incorporated into the foodways of cultures throughout the world. Although the methods are diverse, what they all have in common is an attempt to create an environment that is inhospitable to microorganisms such as molds, yeast, and bacteria.

The astonishing fact about food preservation is that it permeated every culture at nearly every moment in time. To survive ancient man had to harness nature. In frozen climates he froze seal meat on the ice to prevent long searches for food in harsh weather. In tropical climates he dried foods in the sun. Food by its nature begins to spoil the moment it is harvested. Before the concept of food preservation developed, humans were forced to travel from location to location in order to locate fresh foods. Food preservation enabled ancient man to make roots and live in one place and form a community. He no longer had to consume the kill or harvest immediately, but could preserve some for later use. Each culture preserved their local food sources using the some of the same basic methods of food preservation, the earliest probaly being freezing, drying and fermentation.

Food historians believe pre-historic people preserved food accidentally through geography and living conditions. Things froze in icy northern areas and dried out in the hot Mediterranean sun. Early cave-dwellers likely stumbled onto smoking food after hanging it in the same caves where they made fires for warmth and light. Native Americans in ancient times sun-cured buffalo meat. In places where people had large deposits of salt, they used it cure foods. In ancient Mesopotamia (Iraq), during the Akkadian Empire, people cured and smoked meat, dried apples, and preserved fruit in honey.

Techniques for drying foods date back to ancient times, when fruits and vegetables were dried in the sun or on an open stove. By 1000 BC, the Chinese were using salt, spices, and smoking to create a sterile environment for different food products. Salt also acts as a dehydrating agent and is particularly useful for fish and meat. Salted meat served explorers and military forces well because of its stability and portability, and it was a technique that lasted into the twentieth century.

And pickles? Most everyone in ancient times made pickles, either with a brine or by fermentation. People in India were likely the first to make cucumber pickles over 3,000 years ago. Ancient Egyptians and Babylonians pickled fish, including catfish, salmon and even pickled goose. Those veggie-stuffed dolmas you get with your salad platter at Greek restaurants? In ancient times, people were picking, rolling and pickling those grape leaves in North Africa, the Mediterranean and the Middle East. And ancient Chinese people used vinegar brines for pickling proteins, from eggs to a variety of meats, including rabbit, venison and goat. Pickling was amongst the most popular in the Roman time period which is a process consisting of using acids, such as vinegar, to oxidize bacteria in food to acetic acid which will not cause illness when consumed.

It was also discovered very early that making cheese could preserve dairy products, grape juice could be fermented into wine that would last for years at normal temperatures, and even cabbage could be preserved by converting it to fermented sauerkraut. North American Indians made pemmican by drying the meat of buffalo or deer and then mixing it with a large amount of fat. This was effective because the fat presumably excluded oxygen.

Food preservation changed significantly, however, in the early 1800s, when the Frenchman Nicolas Appert made "the seasons stand still" by inventing a technique to preserve foods in glass jars. Appert opened a factory at Massy but also described his process for anyone to follow. Appert had discovered that unwanted bacteria were destroyed by placing the jars in boiling water for a specific time period depending on the food and then sealing the jar under these sterile conditions. Although Appert preferred glass because he thought it was the best for keeping out oxygen, others soon followed with metal containers, and the modern canning industry was born.

Some of the foods we enjoy today in the South are descendants of old preservation methods which kept food from being wasted before it could be eaten. Okra grows prolifically in the region, so pickling has always been a great way to preserve it before it went bad. The same goes for late-season green tomatoes. Chowchow is another way to preserve the last vegetables of the harvest.

Despite the differences in climates, many of the food preservation techniques from Europe, Africa, and other parts of the world eventually found a home here, often with new twists. Some of the sweet-and-sour flavors in chowchow, piccalilli, chutneys and spiced fruits find their roots in Malaysia, but were introduced to the South by West Africans, in whose culture drying and salting fish were also common. Other types of pickling traditions came from Germany. Pickled eggs and pigs’ feet — offered as free bar snacks and sold at Southern gas station for generations — are examples of achieving food sustainability by preserving the entire animal. And biscuits and gravy? Those came from the method of preserving ground meat cooked into patties, stored in crocks and layered with rendered lard. You’d scoop out patties with fat, and use them to make sausage gravy. Additional lard provided the fat for biscuits.

What is Food Preservation

Food preservation is the process of treating and handling food to stop or slow down spoilage (loss of quality, edibility or nutritional value) and thus allow for longer storage.

Preservation usually involves preventing the growth of bacteria, yeasts, fungi, and other micro-organisms (although some methods work by introducing benign bacteria, yeasts or fungi to the food), as well as retarding the oxidation of fats which cause rancidity. Many processes designed to preserve food will involve a number of food preservation methods. Preserving fruit, by turning it into jam, for example, involves boiling (to reduce the fruit's moisture content and to kill bacteria, yeasts, etc.), sugaring (to prevent their re-growth) and sealing within an airtight jar (to prevent recontamination).

Maintaining or creating nutritional value, texture and flavour is an important aspect of food preservation, although, historically, some methods drastically altered the character of the food being preserved. In many cases these changes have now come to be seen as desirable qualities – cheese, yoghurt and pickled onions being common examples.

Drying

Drying is one of the most ancient food preservation techniques. In ancient times the sun and wind would have naturally dried foods. Evidence shows that Middle East and oriental cultures actively dried foods as early as 12,000 B.C. in the hot sun. Later cultures left more evidence and each would have methods and materials to reflect their food supplies—fish, wild game, domestic animals, etc.

Vegetables and fruits were also dried from the earliest times. The Romans were particularly fond of any dried fruit they could make. In the Middle Ages purposely built “still houses” were created to dry fruits, vegetables and herbs in areas that did not have enough strong sunlight for drying. A fire was used to create the heat needed to dry foods and in some cases smoking them as well.

Drying works by removing water, the ingredient needed for all forms of life to survive, from the food, which inhibits the growth of microorganisms and hinders quality decay. Drying food using sun and wind to prevent spoilage has been practised since ancient times, and was the earliest form of food curing. Water is usually removed by evaporation (air drying, sun drying, smoking or wind drying) but, in the case of freeze-drying, food is first frozen and then the water is removed by sublimation. Bacteria, yeasts and molds need the water in the food to grow, and drying effectively prevents them from surviving in the food.

Many different foods are prepared by dehydration. Good examples are meat such as prosciutto (a.k.a. Parma ham), bresaola, and beef jerky. Dried and salted reindeer meat is a traditional Sami food. First the meat is soaked / pickled in saltwater for a couple of days to guarantee the conservation of the meat. Then the meat is dried in the sun in spring when the air temperature is below zero. The dried meat can be further processed to make soup.

Another example of preserving food through drying are the pumpkin mats made by the early Pawnee and Wichita peoples of Kansas. Historically, Native Americans grew pumpkins in gardens along the river banks. Strips of pumpkin were dried and woven into mats for storage. The dried pumpkin would be used to flavor soups and other dishes. Tribes such as the Kiowa and the Comanche often traded buffalo meat to the Pawnees and Wichitas for pumpkin mats.

Fruits change character completely when dried: the plum becomes a prune, the grape a raisin; figs and dates are also transformed in new, different products, that can be eaten as they are or else after rehydration.

Freeze dried vegetables are often found in backpackers food, hunters, military, etc. The exception to this rule are bulbs, such as garlic and onion, which are often dried. Also chilis are frequently dried. Edible and psilocybin mushrooms, as well as other fungi, are also sometimes dried for preservation purposes, to affect the potency of chemical components, or so they can be used as seasonings.

For centuries, much of the European diet depended on dried cod, known as salt cod or bacalhau (with salt) or stockfish (without). It formed the main protein source for the slaves on the West Indian plantations, and was a major economic force within the triangular trade. Dried shark meat, known as Hákarl, is a delicacy in Iceland.

Home drying of vegetables, herbs, fruit and even meat (to produce jerky) can be carried out in the home employing sun drying or using electrical dehydrators (household appliance). Preservatives such as potassium metabisulphite, or BHA, BHT for meats may be used. These preservatives are not required, however dried products without these preservatives may require refrigerator or freezing to ensure a long period of storage.

Smoking

Most of the other forms of food preservation used prior to canning and refrigeration employed naturally produced chemicals to retard the growth of organisms that produce spoilage. The smoking of meat and fish, for example, leaves compounds in the meat the destroy microorganism. smoking also partly preserves the meat by lowering its moisture content. Usually meat is soaked in brine or salted for a short time before smoking. The meat is then usually rinsed with warm water and allowed to drain before it is placed in the smokehouse.

Many containers are used for smoking meat. A sealed box or barrel may be used, but at one time many farms had a proper smokehouse for the large-scale preservation of meat. Generally such a building has a series of hooks for hanging the food, a fire box to provide the smoke, and small holes to create enough ventilation to draw smoke from the fire. In most cases the fire box is connected to the smokehouse with a small tunnel to reduce the amount of heat to which the food is subjected. This is to prevent the meat from being partly cooked.The house is often heated in the winter because smoke will not penetrate meat if it is frozen. many materials can be used to produce the smoke. Although chips from hardwoods such as hickory are often favored, bark and corn cobs are frequently used. Meat may be smoked for up to three weeks before it is properly done.

In the Croatian American community of Strawberry Hill in Kansas City, Kansas, families have traditionally made kobasica, a spicy sausage. many houses on the hill have smokehouses in their backyards, although not all are in use today. Members of the community continue to enjoy kobasica whether it is smoked at home or at a neighborhood meat shop.

Freezing

Freezing was an obvious preservation method to the appropriate climates. Any geographic area that had freezing temperatures for even part of a year made use of the temperature to preserve foods. Less than freezing temperatures were used to prolong storage times. Cellars, caves and cool streams were put to good use for that purpose.

In America, estates had icehouses built to store ice and food on ice. Soon the “icehouse” became an “icebox”. In the 1800’s mechanical refrigeration was invented and was quickly put to use. Also in the late 1800’s Clarence Birdseye discovered that quick freezing at very low temperatures made for better tasting meats and vegetables. After some time he perfected his “quick freeze” process and revolutionized this method of food preservation.

Fermentation

Fermentation was not invented, but rather discovered. No doubt that the first beer was discovered when a few grains of barley were left in the rain. Opportunistic microorganisms fermented the starch-derived sugars into alcohols. So too can be said about fruits fermented into wine, cabbage into Kim chi or sauerkraut, and so on. The skill of ancient peoples to observe, harness, and encourage these fermentations are admirable. Some anthropologists believe that mankind settled down from nomadic wanderers into farmers to grow barley to make beer in roughly 10,000 BC. Beer was nutritious and the alcohol was divine. It was treated as a gift from the gods.

In fermentation the growth of specific microorganisms is encouraged. These beneficial microorganism in turn produce chemicals that inhibit the growth of those causing spoilage. Fermentation depends on the production of alcohol in the case of wine, acetic acid in the case of vinegar, or lactic acid in the case of sauerkraut to destroy or slow the growth of microorganisms. Fermentation of the kind used to make sauerkraut depends upon the properties of salt as well as the fermentation process. making sauerkraut combine a small amount of salt with the cabbage to prevent the growth of bacteria that cause the food to spoil immediately. The salt, however, does not prevent the growth of bacteria that cause the production of lactic acid. It is this lactic acid that prevents the growth of undesirable bacteria in the long term.

Fermentation was a valuable food preservation method. It not only could preserve foods, but it also created more nutritious foods and was used to create more palatable foods from less than desirable ingredients. Microorganisms responsible for fermentations can produce vitamins as they ferment. This produces a more nutritious end product from the ingredients.

Burial in the Ground

Burial of food can preserve it due to a variety of factors: lack of light, lack of oxygen, cool temperatures, pH level, or desiccants in the soil. Burial may be combined with other methods such as salting or fermentation. Most foods can be preserved in soil that is very dry and salty (thus a desiccant), or soil that is frozen. Many root vegetables are very resistant to spoilage and require no other preservation than storage in cool dark conditions, for example by burial in the ground, such as in a storage clamp.

Century eggs are created by placing eggs in alkaline mud (or other alkaline substance) resulting in their "inorganic" fermentation through raised pH instead of spoiling. The fermentation preserves them and breaks down some of the complex, less flavorful proteins and fats into simpler more flavorful ones.

Cabbage was traditionally buried in the fall in northern farms in the USA for preservation. Some methods keep it crispy while other methods produce sauerkraut. A similar process is used in the traditional production of kimchi. Sometimes meat is buried under conditions which cause preservation. If buried on hot coals or ashes, the heat can kill pathogens, the dry ash can desiccate, and the earth can block oxygen and further contamination. If buried where the earth is very cold, the earth acts like a refrigerator.

Salting or Curing

Meat also may be preserved by curing it in salt. This treatment is especially good for preserving fish. This can be done either by rubbing dry salt into the meat or by soaking it in brine. Salting or curing draws moisture from the meat through a process of osmosis. Meat is cured with salt or sugar, or a combination of the two. Nitrates and nitrites are also often used to cure meat and contribute the characteristic pink color, as well as inhibition of Clostridium botulinum.

The earliest curing was actually dehydration. Early cultures used salt to help desiccate foods. Salting was common and even culinary by choosing raw salts from different sources (rock salt, sea salt, spiced salt, etc.). In the 1800’s it was discovered that certain sources of salt gave meat a red color instead of the usual unappetizing grey. Consumers overwhelmingly preferred the red colored meat. In this mixture of salts were nitrites (saltpeter). As the microbiology of Clostridium botulinum was elucidated in the 1920’s it was realized that nitrites inhibited this organism.

Salt or brine may be used to preserve vegetables as well. This method was once very common in the United States, but declined with the onset of the 20 century.

Lye

Sodium hydroxide (lye) makes food too alkaline for bacterial growth. Lye will saponify fats in the food, which will change its flavor and texture. Lutefisk uses lye in its preparation, as do some olive recipes. Modern recipes for century eggs also call for lye. Masa harina and hominy use agricultural lime in their preparation and this is often misheard as 'lye'.

Pickling

Pickling is a method of preserving food in an edible anti-microbial liquid. Pickling can be broadly categorized as chemical pickling for example, In chemical pickling, the food is placed in an edible liquid that inhibits or kills bacteria and other micro-organisms. Typical pickling agents include brine (high in salt), vinegar, alcohol, and vegetable oil, especially olive oil but also many other oils. Many chemical pickling processes also involve heating or boiling so that the food being preserved becomes saturated with the pickling agent. Common chemically pickled foods include cucumbers, peppers, corned beef, herring, and eggs, as well as mixed vegetables such as piccalilli. In fermentation pickling, the food itself produces the preservation agent, typically by a process that produces lactic acid. Fermented pickles include sauerkraut, nukazuke, kimchi, surströmming, and curtido. Some pickled cucumbers are also fermented.

Vinegar is produced from starches or sugars fermented first to alcohol and then the alcohol is oxidized by certain bacteria to acetic acid. Wines, beers and ciders are all routinely transformed into vinegars.

Pickling may have originated when food was placed in wine or beer to preserve it, since both have a low pH. Perhaps the wine or beer went sour and the taste of the food in it was appealing. Containers had to be made of stoneware or glass, since the vinegar would dissolve the metal from pots. Never ones to waste anything our ancestors found uses for everything. The left over pickling brine found many uses. The Romans made a concentrated fish pickle sauce called “garum”. It was powerful stuff packing a lot of fish taste in a few drops.

There was a spectacular increase in food preservation in the sixteenth century owing to the arrival in Europe of new foods. Ketchup was an oriental fish brine that traveled the spice route to Europe and eventually to America where someone finally added sugar to it. Spices were added to these pickling sauces to make clever recipes. Soon chutneys, relishes, piccalillis, mustards, and ketchups were commonplace. Worcester sauce was an accident from a forgotten barrel of special relish. It aged for many years in the basement of the Lea and Perrins Chemist shop.

Sugar

Sugar is used to preserve fruits, either in syrup with fruit such as apples, pears, peaches, apricots, plums or in crystallized form where the preserved material is cooked in sugar to the point of crystallisation and the resultant product is then stored dry. This method is used for the skins of citrus fruit (candied peel), angelica and ginger. A modification of this process produces glacé fruit such as glacé cherries where the fruit is preserved in sugar but is then extracted from the syrup and sold, the preservation being maintained by the sugar content of the fruit and the superficial coating of syrup. The use of sugar is often combined with alcohol for preservation of luxury products such as fruit in brandy or other spirits.

Preservation with the use of honey or sugar was well known to the earliest cultures. Fruits kept in honey were commonplace. In ancient Greece quince was mixed with honey, dried somewhat and packed tightly into jars. The Romans improved on the method by cooking the quince and honey producing a solid texture.

The same fervor of trading with India and the Orient that brought pickled foods to Europe brought sugar cane. In northern climates that do not have enough sunlight to successfully dry fruits housewives learned to make preserves—heating the fruit with sugar.

Sugar has strong antiseptic qualities. Any substance that is composed of a minimum of 65 percent sugar is resistant to spoiling. For this reason fruit rarely needs to be fully dried to be preserved. Rather, it must only be dried to the point that 65 percent of its weight is composed of sugar. Fruit may be preserved in sugar in its whole state, as in candied fruit, or packed in a syrup, as in marmalades and preserves. In either case the fruit is first placed in a diluted sugar syrup to allow the sugar to fully penetrate the fruit. The concentration of sugar in the syrup is then increased until the fruit is fully saturated. Some molds will digest sugar, and for this reason a paraffin cap is often poured over jars of jelly or preserves. The paraffin prevents the growth of these molds by depriving them of air.

Canning & Bottling

The ancient methods of food preservation remained unchallenged until the introduction of canning in the 18th century. The method was developed between 1795 and 1809 by Nicolas Appert, a French confectioner. His research was initiated in response to a call from Emperor Napoleon Bonaparte for the discovery of a new method of food preservation to supply the army. Appert discovered that the application of heat to food in sealed glass bottles preserved the food from deterioration. He theorized “if it works for wine, why not foods?” Appert published his results in 1810 for which he received the prize of 12,000 francs.

Appert discovered the method through a series of painstaking experiments, but he never fully understood the reasons why canning worked. Since the germ theory had not been developed, he had no way of knowing that he was preventing spoilage by killing the microorganisms in the food and preventing the introduction of new organisms by sealing the containers. Rather, he thought air alone cause spoilage and that the heating of the air in the containers rendered it harmless. The total destruction of microorganisms in food was an entirely new approach to food preservation, one which made it possible to store food indefinitely.

At first Appert preserved food by placing it in bottles that were heated in a pot of boiling water. Later he experimented with pressure cookers. At first canned vegetables were a curiosity for the wealthy and could only be found in the most exclusive restaurants of Paris. Commercial canning, however, was underway before 1830. At this point metal cans rather than glass were introduced to reduce cost and the problems with breakage in transport. Although food was being canned in the United States in the 19th century, it was the need for canned foods to feed troops in the Civil War that largely promoted its use in America. Troops returning home saw the value of this method of food preservation that, unlike most other means used at that time, had no special storage requirements.

It was not until 1864 when Louis Pasteur discovered the relationship between microorganisms and food spoilage/illness did it become clear why canning preserved foods. Just prior to Pasteur’s discovery Raymond Chevalier-Appert patented the pressure retort (canner) in 1851 to can at temperatures higher than 212ºF. However, not until the 1920’s was the significance of this method known in relation to Clostridium botulinum.

Canning is the process in which foods are placed in sterile jars or cans and heated to a temperature that destroys microorganisms and inactivates enzymes. This heating and later cooling forms a vacuum seal. The vacuum seal prevents other microorganisms from recontaminating the food within the jar or can. Foods have varying degrees of natural protection against spoilage and may require that the final step occur in a pressure cooker. High-acid fruits like strawberries require no preservatives to can and only a short boiling cycle, whereas marginal fruits such as tomatoes require longer boiling and addition of other acidic elements. Low acid foods, such as vegetables and meats require pressure canning.

During the 19th century most home canners did not employ the full sealed container method developed by Appert. Rather they used the so-called "open kettle" method. In this technique the food is placed in liquid and boiled. It is then quickly transferred to jars that have just been boiled and are still hot. Covers are then quickly placed on the jars In the southern United States canners often heated the food for decreasing lengths of time on three consecutive days to eliminate more of the spoilage-causing agents. The open kettle method worked fairly well for food with a high acid content such as tomatoes, rhubarb, pears, or peaches. Open kettle canning, however, frequently damages the fruits or vegetables and has a higher problem with spoilage.

The adoption of the more efficient can-cooked method for home use was dependent on two developments. The first of these was the production of pressure cookers at a cost that made this method economically feasible. Without the efforts of the agricultural extension services, however, it might have taken considerably longer before this technology was made available to the general public. One of the first efforts to disseminate this information was undertaken by the Louisiana Experiment Station in 1905. In the years that followed, home canning techniques were taught through a number of state extension services, leading to their widespread acceptance by the advent of the First World War. The need for food during wartime only served to increase the adoption of canning for home food preservation. Although time consuming, canning proved to be a much more versatile method than any used until that point. In the decades that followed, teaching canning techniques became standard in high school home economics classes. Only with the widespread use of freezers did canning encounter competition in the area of home food preservation.

In the years that followed World War II, the American public practiced home food preservation less frequently. This is partly the result of the movement from farming to other occupations. Once the food used for preservation had to be purchased, it was economical to simply buy food that had already been preserved. Food preservation has declined among agricultural families as well. This is due in part to the declining cost of commercially preserved food. As is the case with most families, those living in rural areas also are feeling the pressure of increased responsibilities that demand more time from family members. This has significantly reduced the time that can be invested in activities such as canning.

Jellying

Food may be preserved by cooking in a material that solidifies to form a gel. Such materials include gelatine, agar, maize flour and arrowroot flour. Some foods naturally form a protein gel when cooked such as eels and elvers, and sipunculid worms which are a delicacy in the town of Xiamen in Fujian province of the People's Republic of China. Jellied eels are a delicacy in the East End of London where they are eaten with mashed potatoes. Potted meats in aspic (a gel made from gelatine and clarified meat broth) were a common way of serving meat off-cuts in the UK until the 1950s. Many jugged meats are also jellied.

Jugging

Meat can be preserved by jugging, the process of stewing the meat (commonly game or fish) in a covered earthenware jug or casserole. The animal to be jugged is usually cut into pieces, placed into a tightly-sealed jug with brine or gravy, and stewed. Red wine and/or the animal's own blood is sometimes added to the cooking liquid. Jugging was a popular method of preserving meat up until the middle of the 20th century.

Potting

A traditional British way of preserving meat (particularly shrimp) is by setting it in a pot and sealing it with a layer of fat. Also common is potted chicken liver; compare pâté.

Refrigeration

Refrigeration preserves food by slowing down the growth and reproduction of micro-organisms and the action of enzymes which cause food to rot. The introduction of commercial and domestic refrigerators drastically improved the diets of many in the Western world by allowing foods such as fresh fruit, salads and dairy products to be stored safely for longer periods, particularly during warm weather.

Vacuum-Packing

Vacuum-packing stores food in a vacuum environment, usually in an air-tight bag or bottle. The vacuum environment strips bacteria of oxygen needed for survival, slowing spoiling. Vacuum-packing is commonly used for storing nuts to reduce loss of flavor from oxidation.