Food is a source of energy for all of us. Unhealthy or spoiled food is the major cause of diseases in human beings, this is known as food poisoning. To prevent this, the food needs to be preserved in a variety of ways. Food preservation is one of the methods to protect food. Food preservation is the technique to prevent food spoilage, food poisoning, and microbial contamination in food.” Food preservation started long back in ancient times. Cooling, freezing, fermentation, sun-drying, etc., are few age old food preservation techniques. With the advent of technology, modern methods of food preservation were developed. Chemicals and other natural substances were used for preservation. These substances are known as preservatives. Listed below is an overview of 10 methods for preserving foods, including today’s popular methods, as well as other old-fashioned and ancient techniques.
1.Canning
Canning is an important, safe method of food preservation if practiced properly. Canning, method of preserving food from spoilage by storing it in containers that are hermetically sealed and then sterilized by heat. It can be used with most foods, including fruits, vegetables, meats, seafood, and some prepared foods. Canning provides a shelf life that typically ranges from one to five years, although under specific circumstances, it can be much longer. A freeze-dried canned product, such as canned dried lentils, could last as long as 30 years in an edible state. Canning requires the purchase of reusable canning jars and rings, one-time use sealing lids. The process was invented after prolonged research by Nicolas Appert of France in 1809, in response to a call by his government for a means of preserving food for army and navy use. The French Army began experimenting with issuing canned foods to its soldiers.
The larger armies of the period required increased and regular supplies of quality food. Appert’s method consisted of tightly sealing food inside a bottle or jar, heating it to a certain temperature, and maintaining the heat for a certain period, after which the container was kept sealed until use. The original fragile and heavy glass containers presented challenges for transportation, and glass jars were largely replaced in commercial canneries with cylindrical tin can or wrought-iron canisters. In 1810 Peter Durand of England patented the use of tin-coated iron cans instead of bottles, and by 1820 he was supplying canned food to the Royal Navy in large quantities. Can consists of a sheet of tin-plated iron that was rolled into a cylinder, onto which the top and bottom were manually soldered. The modern tin can is made of 98.5 percent sheet steel with a thin coating of tin.
2.Freezing
Freezing is a common method of food preservation that slows both food decay and the growth of micro-organisms. Freezing is the process of chilling foods to at least 0°F. It can be used with all foods, including fruits, vegetables, meats, seafood, grains, nuts, dairy, eggs, and prepared foods. True freezing is not possible in the freezer compartment of your refrigerator where the temperature is typically much warmer, between 10°F to 32°F. Freezing is easy to do, if you can afford to buy and operate the relatively expensive appliance. Freezing can damage some foods because the formation of ice crystals causes breakage of the cell membranes. This has no adverse effects in terms of safety, however the food loses its crispness or firmness. Freezing is the old, easiest, most convenient, and least time-consuming method of preserving foods. Most foods freeze well with the exception of produce with a high water content, cream-based items, and cooked starchy foods such as cooked noodles and rice. Freezing occurs when heat is lost from an object, which causes the molecules to slow down and form tighter bonds. Freezing is the opposite of melting, and two steps away from evaporation.
Freezing occurs at below 0 degrees Celsius with water, while some other liquids become a solid at higher or lower temperatures. Most liquids can freeze. It is a necessary step in casting. Freezing means the solidification phase change of a liquid or the liquid content of a substance, usually due to cooling. For most substances, the melting and freezing points are the same temperature; however, certain substances possess differing solid–liquid transition temperatures. Most liquids freeze by crystallization, formation of crystalline solid from the uniform liquid. Many living organisms are able to tolerate prolonged periods of time at temperatures below the freezing point of water. Besides the effect of lower temperatures on reaction rates, freezing makes water less available for bacteria growth. freezing is one of the oldest and most widely used method of food preservation. The method has been used for centuries in cold regions, and a patent was issued in Britain as early as 1842 for freezing food by immersion in an ice and salt brine. The temperature of the water remains at 32°F as the ice crystals grow, and then a rapid temperature drop occurs as the ice crystals cool. Rapid freezing improves the quality of the food. The faster food freezes, the smaller the crystals that form. Small crystals do less damage to cell walls.
3.Drying
Drying is one of the world’s oldest methods of food preservation, with the principles of this process influencing some of the most modern methods of food science. Some of the ancient dehydration methods are still the best ones. All you need is direct sunlight for a number of days and a low humidity atmosphere of below 20%. So, your geography matters, which is why sun-dried foods are such a central part of certain cultures. Drying is the process of dehydrating foods until there is not enough moisture to support microbial activity. It can be used with most foods, including fruits, vegetables, meats, seafood, grains, legumes, and nuts. Food dehydrating is based on one core principle: Quickly remove as much moisture from the food as possible to inhibit the growth of bacteria, mold and yeast. Some people prefer to dry food because it takes less time, money and energy than other food-storage methods, such as canning or freezing. Food dehydration saves money because you can buy or grow seasonal produce to dry and store for year-round use. The first automated drying process was created in 1795 by French inventors Masson and Chollet. The machine fed sliced fruit and vegetables into a hot-air dehydration chamber, with a controlled temperature of 40°C dehydrating produce ready to be pressed and sealed in tin foil. In some cases, the nutritional value and vitamins can be retained through blanching food before drying them, a process that often used when drying vegetables.
There are several different techniques, some are relatively easy to do and require no special equipment. Other methods are Spray Drying food, Freeze Drying Food. The dairy industry is one of the largest processors of dehydrated food. Many dairy products are spray dried, meaning they are automised into a fine mist then brought into contact with hot air. The moisture is instantly removed, leaving only the milk powder as a product. This method is used to make powders such as milk, whey and yeast, as well as some ice creams, cheese and fruit juices. Although spray drying food gives you the product quickly, it is a very expensive technique that requires a lot of energy. As the food is frozen, the moisture in it is turned into ice. It is then put into a vacuum at -45°C and the ice is removed by sublimation, meaning it goes directly from a solid to a gas, without ever entering liquid form. The advantage is that the food will maintain its structure and flavour, and almost any food can be freeze dried. This method is also be expensive. Many foods lose vitamins and other useful nutrients in the process.
4.Fermenting
During fermentation, lactic acid bacteria consume the sugars or carbohydrates in the food, producing acid and flavor compounds. When fermenting foods at home, we rely on creating the environment needed for a safe and effective ferment. Fermenting is the process of encouraging the growth of “good bugs” to inhibit the “bad bugs” that can spoil food. It can be used with many types of foods, including fruits, vegetables, meats, seafood, grains, legumes, dairy, and eggs to produce a wide range of products such as wine (from grapes), sauerkraut (cabbage), cured sausage (meat), and yogurt (milk). Cauliflower, carrots, cucumbers, and daikon radishes…just about any vegetable can be fermented. Cheese, yogurt, sauerkraut, kimchee, olives, salami, jerky, and bread; also, beverages such as hard cider, wine, beer, and coffee were all produced by the fermentation process. To allow for the growth of the desirable lactic acid bacteria, the process needs sufficient water, nutrients, an appropriate amount of salt, and the absence of oxygen/air.
The beginner should use tested recipes that are science based, provide the appropriate salt concentration and amounts of vegetable and, if needed, added water. Many fermented products can be produced without any special equipment. The method for each type of product is relatively easy, but requires attention to detail. Food fermentation serves five main purposes: to enrich the diet through development of a diversity of flavors, aromas, and textures in food substrates; to preserve substantial amounts of food through lactic acid, alcohol, acetic acid, and alkaline fermentations; to enrich food substrates with protein, essential amino acids, and vitamins; to eliminate antinutrients; and to reduce cooking time and the associated use of fuel. The French chemist Louis Pasteur founded zymology, when in 1856 he connected yeast to fermentation. When studying the fermentation of sugar to alcohol by yeast, Pasteur concluded that the fermentation was catalyzed by a vital force, called “ferments”, within the yeast cells.
5.Pickling
Pickling is the process of preserving or extending the shelf life of food by either anaerobic fermentation in brine or immersion in vinegar. It is the process of soaking food in a solution containing salt, acid, or alcohol. The pickling procedure typically affects the food’s texture and flavor. The resulting food is called a pickle, or, to prevent ambiguity, prefaced with pickled. Foods that are pickled include vegetables, fruits, meats, fish, dairy and eggs. Like most vegetables, pickles are almost all water and have very little fat or protein. A distinguishing characteristic is a pH of 4.6 or lower, which is sufficient to kill most bacteria. Pickling was used as a way to preserve food for out-of-season use and for long journeys, especially by sea. Pickling may also improve the nutritional value of food by introducing B vitamins produced by bacteria and it helps digestion.
South Asia has a large variety of pickles. Most methods require no special equipment. However, pickled foods can be unsafe if prepared carelessly or stored at room temperature. Pickling is often combined with another method, such as Fermenting, Canning, or just Refrigerating. Fermented pickles are full of good bacteria called probiotics, which are important for gut health. Carotene is a powerful compound that’s been shown to help lower your chances of dying of heart disease, stroke, cancer, respiratory diseases, and other conditions. November 14th is National Pickle Day. In chemical pickling, the fruits or vegetables to be pickled are placed in a sterilized jar along with brine, vinegar, or both, as well as spices, and are then allowed to mature until the desired taste is obtained.
6.Dry Salting
Dry salting is a fermentation method that involves sprinkling salt onto a dry vegetable to draw out the water. The vegetable is then pounded to further break down the cell walls and release juice in order to create enough liquid brine to submerge the vegetables. Place prepared seafood in a single layer in a container. Sprinkle generously with salt. Turnover and salt the other side. Another layer can be placed on top and the salting process repeated. Use about a quarter of the seafood weight in salt. Cover, and leave in a cool place (20°C or less) for the required time. In hot weather it is preferable to store in the chiller. Rinse under cold running water. Dry with disposable paper towels. After Salting, it will be ready to serve. It is one of the oldest methods of preserving food, and two historically significant salt-cured foods are salted fish (usually dried and salted cod or salted herring) and salt-cured meat (such as bacon).
Vegetables such as runner beans and cabbage are also often preserved in this manner. Salting is used because most bacteria, fungi and other potentially pathogenic organisms cannot survive in a highly salty environment, due to the hypertonic nature of salt. Dry salting is used for meat, fish, and vegetables. A low salt concentration, promotes fermentation, while a high salt concentration, prevents microbial growth and preserves the food in a more or less fresh, although salty state. Many people familiar with the technique consider salted vegetables such as green beans to be far superior in taste and texture than canned or frozen beans. This old-fashioned method was promoted in the early twentieth century as an alternative to canning, in order to conserve glass, tin, and fuel in time of war.
7.Curing
Curing is any of various food preservation and flavoring processes of foods such as meat, fish and vegetables, by the addition of salt, with the aim of drawing moisture out of the food by the process of osmosis. Curing is similar to pickling, and uses salt, acid, and/or nitrites. The nitrate and nitrite compounds themselves are not harmful, however, and are among the antioxidants found in fresh vegetables. Curing is used for meat and fish. Simple, modern curing methods often reduce the amount of salt and nitrites, which may require that you refrigerate or freeze the final product. Shelf-stable products require the use of adequate amounts of nitrites and a complex drying process using special equipment and exacting technique. Some curing methods also employ a secondary process such as fermenting, smoking, or sealing. Meat preservation in general comprises the set of all treatment processes for preserving the properties, taste, texture, and color of raw, partially cooked, or cooked meats while keeping them edible and safe to consume.
While meat-preservation processes like curing were mainly developed in order to prevent disease and to increase food security, the advent of modern preservation methods mean that in most developed countries today curing is instead mainly practised for its cultural value. For lesser-developed countries, curing remains a key process in the production, transport and availability of meat. Curing with salt and sugar may be called salting, salt-curing, sugar-curing or honey-curing. The application of pellets of salt, called corns, is often called corning. Curing in a water solution or brine is called wet-curing or pickling or brining. Paul Bertolli notes that a pickle contains nitrite in addition to salt. The curing of fish is sometimes called kippering. Salt inhibits the growth of spoilage-causing microorganisms by drawing water out of microbial cells through osmosis. Concentrations of salt up to 20% are required to kill most species of unwanted bacteria. Salted meat and fish are commonly eaten as a staple of the diet in North Africa, Southern China and in the Arctic where they are associated with nasopharyngeal cancer caused by infection by the Epstein-Barr Virus.
8.Smoking
Smoking is the process of flavoring, cooking, or preserving food by exposing it to the smoke from burning plant materials like wood and that too hardwood. Drying and Smoking is one of the oldest methods of preserving foodstuffs. Removing the moisture from food helps prevent bacterial and fungal growth which would ruin stored foods. Smoking, in food processing, the exposure of cured meat and fish products to smoke for the purposes of preserving them and increasing their palatability by adding flavour and imparting a rich brown colour. Food preservation is the process of treating foods in a way that prevents spoilage caused by micro-organisms. The drying action of the smoke tends to preserve the meat, though many of the chemicals present in wood smoke are natural preservatives as well. Meats are less likely to turn rancid or grow mold than unsmoked meats. Whether done on a commercial or a home scale, the smoking technique involves hanging the meat or placing it on racks in a chamber designed to contain the smoke. Commercial smokehouses, usually several stories high, often use steampipes to supplement the heat of a natural sawdust fire.
Hickory sawdust is the preferred fuel. Whatever the size of the smoking operation, it is imperative that a hardwood fire be used. In Europe, alder is the traditional smoking wood, but oak is more often used now, and beech to a lesser extent. In North America, hickory, mesquite, oak, pecan, alder, maple, and fruit-tree woods, such as apple, cherry, and plum, are commonly used for smoking. Smoking can be done in four ways: cold smoking, warm smoking, hot smoking, and through the employment of “liquid smoke”. The softwood of conifers such as spruce and pine contains pitch, which produces a film on the meat and imparts a bitter taste. Generally, smokehouse temperatures vary from 109 to 160 °F (43 to 71 °C), and smoking periods vary from as short as a few hours to as long as several days, depending on the type of meat and its moisture content. After smoking, the meat is chilled as rapidly as possible and cut and wrapped for the retail trade. Here we can preserve not only meat, fowl, and fish but also cheeses, nuts and seeds, hard-boiled eggs, and berries, as well as the variety meats including heart, tongue, and liver.
9.Sealing
Sealing is a process of covering food to keep out air, which delays the activity of spoilage organisms. It is used primarily as a complementary process to other methods such as drying or freezing. The goal is to keep oxygen out of food and thus ‘suffocate’ bacteria. Bacteria (good and bad) cannot grow without oxygen. Sealing food means to prohibit bacterial growth and thus preserve food. Both Fat Sealing and Vacuum Sealing methods are relatively easy. Vacuum sealing greatly extends the lifespan of many different kinds of food, from cheese to meat to soup. Sealing saves money. Preserving food for longer means less food spoilage and therefore less wastage of food.
Sealing allows you the option to buy food in bulk at a reduced cost and safely store it for future use. Instead of throwing out leftovers or forcing yourself to eat everything within a day, just vacuum seal and keep it for months. By sealing your food and removing air, the flavours, texture, and moisture of the food will be retained. Plus, you’ll also get much more taste out of your stored food as vacuum sealing will help to preserve nutritional value in food. Vacuum sealing foods protects them from freezer burn and dehydration. Vacuum sealing holds in the moisture, juices, and flavor of the food. You’ll notice the difference in taste. Vacuum sealing food adds a layer of protection from external sources.
10.Cellaring
Cellaring is the process of storing foods in a temperature, humidity, and light controlled environment. There are many different methods for cellaring food, all of which are relatively easy to do. Root cellaring is one of the easiest and most energy-efficient ways to store your fruits and vegetables by using the earth’s natural temperatures. A root cellar is an old-fashioned winter food storage preservation method. The ability of some vegetables and fruit to keep for months in favorable cellar conditions stems in part from the fact that they are not entirely inanimate even after picking. In some cases plants are transplanted from the field to the dirt floor of a cellar in autumn, and they then continue living in the cellar for months. With a renewed interest in gardening, food security, and even sustainable living, root cellars have returned.
While root vegetables aren’t expensive to buy, the quality of a homegrown potato or beet is far superior, plus grocery stores do not always carry vegetables year-round. Having a root cellar is like having a six-month supply of quality vegetables on hand. There is a certain peace of mind of having enough food security without being at the mercy of grocery stores and potential interruptions in the supply chain. Vegetables stored in the root cellar primarily consist of potatoes, turnips, and carrots. Other food supplies placed in the root cellar during winter months include beets, onions, jarred preserves and jams, salt meat, salt turbot, salt herring, winter squash, and cabbage. Water, bread, butter, milk, and cream are sometimes stored in the root cellar.
