Different Methods of Food Preservation
Food preservation is known “as the science which deals with the process of prevention of decay or spoilage of food thus allowing it to be stored in a fit condition for future use”. Preservation ensures that the quality, edibility and the nutritive value of the food remains intact. Preservation involves preventing the growth of bacteria, fungi and other microorganisms as well as retarding oxidation of fats to reduce rancidity. The process also ensures that there is no discolouration or aging. Preservation also involves sealing to prevent re-entry of microbes. Basically food preservation ensures that food remains in a state where it is
Drying is the oldest method of food preservation. This method reduces water activity which prevents bacterial growth. Drying reduces weight so foods can be carried easily. Sun and wind are both used for drying as well as modern applications like Bed dryers, Fluidized bed dryers, Freeze Drying, Shelf dryers, Spray drying and Commercial food dehydrators and Household oven. Meat and fruits like apples, apricots and grapes are some examples of drying with this method. Freezing is keeping prepared food stuffs in cold storages. Potatoes can be stored in dark rooms but potato preparations need to be frozen. Smoking is the process that cooks, flavours and preserves food exposing it to the smoke from burning wood. Smoke is antimicrobial and antioxidant and most often meats and fish are smoked. Various methods of smoking are used like Hot smoking, Cold smoking, Smoke roasting and Smoke baking. Smoking as a preservative enhances the risk of cancer. Vacuum packing creates a vacuum by making bags and bottles airtight. Since there is no oxygen in the created vacuum bacteria die. Usually used for dry fruit. Salting and Pickling: Salting also known as curing removes moisture from foods like meat. Pickling means preserving food in brine (salt solution) or marinating in vinegar (acetic acid) and in Asia, oil is used to preserve foods. Salt kills and inhibits growth of microorganisms at 20% of concentration. There are various methods of pickling like chemical pickling and fermentation pickling. In commercial pickles sodium benzoate or EDTA is added to increase shelf life. Sugar is used in syrup form to preserve fruits or in crystallized form if the material to be preserved is cooked in the sugar till crystallization takes place like candied peel and ginger. Another use is for glazed fruit that gets superficial coating of sugar syrup. Sugar is also used with alcohol to preserve luxury foods like fruit in brandy. Lye also known as Sodium hydroxide turns food alkaline and prevents bacterial growth. Canning and bottling means sealing cooked food in sterile bottles and cans. The container is boiled and this kills or weakens bacteria. Foods are cooked for various lengths or time. Once the can or bottle is opened the food is again at risk of spoilage. Jellying is preserving food by cooking in a material that solidifies to form a gel. Fruits are generally preserved as jelly, marmalade or fruit preserves and the jellying agent is pectin that is naturally found in fruit. Sugar is also added. Potting is a traditional British way of preserving meat by placing it in a pot and sealing it with a layer of fat. Jugging is preserving meat by stewing it in an earthenware jug or casserole. Brine or wine is used to stew meat in and sometimes the animal’s blood. Burial in the ground preserves food as there is lack of light and oxygen and it has cool temperatures, pH level, or desiccants in the soil. Used to preserve cabbages and root vegetables. Pulsed Electric Field Processing is a new method of preservation that uses brief pulses as strong electric field to process cells. This is still at an experimental stage. Modified atmosphere preserves food by operating on the atmosphere around it. Salad crops that are difficult to preserve are packaged in sealed bags with an atmosphere modified to reduce the oxygen concentration and increase the carbon dioxide concentration. Controlled use of organism is used on cheese, wine and beer as they are preserved for a longer time. This method uses benign organisms to preserve food by introducing them to food where they make an environment which is not suitable for harmful pathogens to grow. High pressure food preservation is a method that presses foods inside a vessel by exerting 70,000 pounds per square inch or more of pressure. This disables microorganisms and prevents spoilage but food retains its appearance, texture and flavour. Modified Atmosphere Packaging extends the shelf life of fresh food products. The atmospheric air inside a package is substituted with a protective gas mix which ensures that the product will stay fresh for as long as possible. Besides these there is Pasteurisation and Irradiation are also used. Various food preservation techniques to increase shelf-life of the products*
* The contents of the table have been sourced from the information document from FSSAI & CODEX. Skip to content
9 min read
We’re spoiled for choice when it comes to food preservation. To extend the longevity of food used at home or in your food business, you can use refrigeration, freezing, canning, sugaring, salting, and even vacuum packing. Plus, food experts are constantly researching new preservation methods to expand our options. Centuries of trial and error have taught us the safest methods of food preservation, which you must prioritise if you want to retain the quality and hygiene of stored food. The good news is that, with the right guidance and materials, you can easily do so in any setting. The Importance of Food PreservationFood preservation refers to the processes you use to prepare food for safe, long-term storage, whether you plan to use it at home, for prep in a commercial kitchen, or to sell directly to consumers. Preservation methods help inhibit bacterial growth and other types of spoilage, meaning the food is safe and satisfying to eat in the future. There are three reasons why food preservation is important:
Certain food preservation methods can be tricky, but chances are you’ll gain a real sense of satisfaction and pride when you successfully apply them. Also, as many preservation methods require precision and care to maintain food safety, you’ll strengthen your awareness of food hygiene risks and good practices.
Our Food Hygiene Training is designed to ensure a comprehensive knowledge of all food safety and hygiene procedures. Common Methods of Food PreservationFood preservation methods range from the simple process of chilling to more complex procedures such as canning. Many are creative options that help you mix things up at home or sell food in various forms of packaging. Others help you keep your inventory in a commercial kitchen for much longer, which means you reduce waste and increase profit. The 6 sections below look at various food preservation methods you can use and the safest, most effective way to do them.
Although refrigeration is a basic storage method nowadays, it was once a luxury. Storing food at a low temperature is the simplest, and often safest, way to store many types of food, as the food you plan to chill usually requires minimal preparation – or it’s already done for you. Fridges preserve the quality and safety of food because the cold slows bacterial growth and minimises spoilage. Depending on the type of food, it can last between a few days and a few weeks in the fridge before the texture and taste deteriorate. To safely refrigerate food, you should:
Throughout history, various civilisations cut and stored ice or snow to create conditions for refrigeration. Ice was even shipped around the world.
If stored properly, frozen food can last for months. In fact, because bacteria cannot grow when frozen, food you keep in the freezer can remain safe to eat for almost indefinite periods of time. However, it will eventually deteriorate in quality and become unappetising, so you should use most frozen food within a few months or a year. To safely freeze food, you should:
If the power cuts, don’t open the freezer door. Food usually remains frozen for about 24 hours even if the freezer shuts off, so you shouldn’t have to throw anything away once the power returns.
Preserving food in a high-sugar environment stops bacterial growth by reducing the food’s water content. It works particularly well for fruit: you can make jam and marmalade that lasts for a long time, and you can use canning to store it (see the section below). All sorts of sugary substances work well to preserve food, including sugar granules, sugar syrup, or honey. Some sugaring recipes even use alcohol alongside sugar to preserve certain foods. You may use sugaring to preserve foods such as:
Using an excessive amount of sugar comes with health risks, but if you reduce the amount of sugar to lower than what is necessary, you may allow the food to spoil. Make sure you follow suitable sugaring recipes shared online or in books to get the right amount, and be sure to consume sugared foods in moderation.
The average person consumes 24 kilos of sugar a year: six times the recommended amount.
Similar to sugaring, salt draws water out of food and stops bacterial growth. In high concentrations, it can even destroy bacteria cells, although by this point the food is likely unappetising. There are two forms of salting:
As with sugar, excessive salt consumption can harm health, so you should follow suitable salting recipes found online or in published food preservation books. You also need to use salt specifically designed for pickling or a Kosher salt.
The Ancient Romans valued salt so highly as an ingredient for preserving food that they used it as a form of currency.
Keeping food canned significantly extends its lifespan – but only if done correctly. The canning process preserves food by removing oxygen through an airtight seal and containing food in an acidic, sugary, or salty environment, where bacteria cannot thrive. You should follow a safe, proper canning process:
Follow these canning steps:
It’s critical that you follow a tested canning process to increase the longevity and safety of food. If improperly canned, food containing C. botulinum may produce toxins that cause botulism poisoning: a rare but life-threatening condition. Fortunately, C. botulinum remains inactive in high-acid environments, so make sure you follow any steps that require adding acids.
In response to Napoleon’s concern for soldiers dying from malnutrition, a man named Nicholas Appert invented canning in the early 1800s.
Similar to canning, vacuum packing deprives bacteria of oxygen by creating an airtight atmosphere. While food may not last for as long as canned goods, vacuuming still extends its storage life for much longer than keeping food in the fridge or in a cupboard. Vacuum packing also has value as a preservation method because it preserves the quality without the need for other ingredients (unlike canning). It usually maintains the food’s smell, colour, taste, and texture – which is particularly desirable for meat you intend to cook rare. In the absence of air, vacuum packed food also retains its moisture, which ensures optimum food quality. Beyond preservation, vacuum packing also works well for food preparation. Many chefs vacuum pack specific ingredients and cook it at a precise temperature to produce unique results. To safely vacuum pack food, you should:
You can follow certain methods that don’t require a machine to vacuum pack food if you like, but they usually sacrifice food safety and produce varying results. Remember: to prevent botulism, airtight packaging must be spot on. In a commercial setting, always use suitable equipment to vacuum pack. You’ll preserve food safely and make it safe to eat at a later date.
You can vacuum seal a lot of foods, but you should avoid soft cheese, mushrooms, broccoli, cabbage, and Brussels sprouts. They give off gases that expand the bag and lead to spoilage. What to Read Next:
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