Introduction
Food preservation is the process of treating and handling food to stop or slow down spoilage (loss of quality, edibility or nutritional value) and prevent foodborne illness.
There are several different methods of food preservation, including:
- Canning
- Freezing
- Dehydration
- Fermentation
- Pickling
- Refrigeration
- Vacuum sealing
Thermal processing
Thermal processing is a method of food preservation that uses high temperature to destroy microorganisms that cause food spoilage. The main purpose of thermal processing is to make food safe to eat by reducing the number of microorganisms that can cause foodborne illness. Thermal processing can also be used to extend the shelf life of food.
Canning
Depending on the food, canning involves heating the food to a temperature that will destroy any microorganisms that are present. This can be done by boiling the food in water or by using a pressure cooker. Once the food has been processed, it is sealed in an airtight container to prevent recontamination.
Canning is a great way to preserve food because it is very effective at destroying microorganisms. However, it is important to remember that not all foods can be canned. For example, fresh fruits and vegetables must be blanched before they are sealed in order to prevent them from spoiling.
Pasteurization
Pasteurization is a type of thermal processing in which food is exposed to high temperature for a short period of time in order to kill food borne pathogens. The process was first developed by Louis Pasteur in 1864, and it has since been used to prolong the shelf life of many food products, including milk, juices, beer, and vinegar.
There are two main types of pasteurization: batch pasteurization and continuous pasteurization. In batch pasteurization, food is heated in batches, and then cooled before being packaged. In continuous pasteurization, food is heated as it moves through a heat exchanger, and then it is immediately cooled before being packaged.
The temperature and duration of the pasteurization process depends on the food being processed. For milk, the most common method is high-temperature short-time (HTST) pasteurization, in which milk is heated to 161°F (72°C) for 15 seconds. Other methods include ultra-high temperature (UHT) pasteurization, in which milk is heated to 280°F (138°C) for two seconds; flash pasteurization, in which milk is heated to 190°F–200°F (88°C–93°C) for one second; and aseptic processing, in which milk is heated to 275°F (135°C) for at least two seconds.
Pasteurized foods must be stored under refrigeration to prevent spoilage.
Blanching
Blanching is a thermal processing method used to primarily inactivate enzymes. Enzymes are proteins that act as catalysts during food spoilage, causing off flavors and textural changes. Blanching can also be used to soften food, wilt greens, remove undesirable peel from fruits and vegetables, or make pigment more stable and less likely to bleed in foods.
Blanching is achieved by briefly submerging food in boiling water or exposing it to steam. The length of time food is exposed to heat during blanching is critical; if it is too short, enzymes will not be inactivated, and if it is too long, flavor, color, and nutrients will be degraded.
After blanching, foods must be rapidly cooled to stop the cooking process; this can be done by submerging the food in ice water or by using a forced-air cooling method. Blanched foods must then be drained well before packaging to avoid a soggy product.
Chemical preservatives
Chemical preservatives are added to food to prevent spoilage and prevent the growth of bacteria, yeast, and mold. Common chemical preservatives include sulfur dioxide, sodium nitrite, and sodium benzoate.
Acidification
Acidification is the process of adding an acid to a food or drink. The acid lowers the pH of the food, making it more acidic. Acidification can preserve food by preventing the growth of microorganisms. It can also enhance the flavor of some foods.
There are three common types of acids used in food preservation:
-citric acid
-lactic acid
-acetic acid
Citric acid is found in citrus fruits like lemons and oranges. It is used to preserve foods like jams and jellies. Lactic acid is found in sour milk and yogurt. It is used to preserve meats and vegetables. Acetic acid is found in vinegar. It is used to preserve pickles and other foods.
Salting
Salting is a method of food preservation that has been used since ancient times. Salt draw water out of bacteria, yeasts, and other microorganisms, making it difficult for them to grow and reproduce. This process can be used to preserve both cooked and raw foods.
The amount of salt required for preservation will vary depending on the food being preserved and the method of storage. For example, meat can be preserved with as little as 2% salt by weight, while fish requires at least 5%.
There are two main methods of salting food: dry-salting and brine-salting. Dry-salting involves Rubbing salt into the surface of the food, which is then left to air-dry. This method is typically used for meats, fish, and some vegetables. Brine-salting involves submerging the food in a solution of water and salt (usually between 5 and 20% salt by weight). This method is typically used for vegetables, eggs, and some cheeses.
Salted foods will last much longer than their un-salted counterparts; however, they will also have a distinctly salty flavor. When using salted foods, it is important to rinse off any excess salt before cooking or eating.
Sugar
Sugar is a multifunctional ingredient in processed foods. It not only adds sweetness and body, but also acts as a preservative. Sugar inhibits the growth of microorganisms by binding water and preventing bacteria from multiplying.
The main forms of sugar used in the food industry are sucrose, dextrose, glucose syrup, fructose and maltose. Sucrose, or table sugar, is made from sugar cane or sugar beets and is the most commonly used type of sugar. Dextrose is a form of sugar made from starch that is often used in processed foods because it is less expensive than sucrose. Glucose syrup is made from hydrolyzed starch and is used to add sweetness and body to processed foods. Fructose, or fruit sugar, is found in honey and fruits. Maltose, or malt sugar, is made from hydrolyzed starch and is used to add sweetness and body to processed foods.
Drying
Drying is a method of food preservation that works by removing water from food. This can be done either naturally, through sun drying or air drying, or artificially, through a dehydrator or an oven. Drying food slows down the growth of bacteria and fungi, which can cause food to spoil.
Dehydration
Dehydration is a process where water is removed from an object, usually using heat. Dehydration can be used to preserve food, and it is often used industrially to make powders and other products.
The process of dehydration involves the removal of water molecules from a substance, typically using heat. When dehydration is used to preserve food, the water molecules are removed from the food, which prevents the growth of microorganisms and the spoilage of the food. Dehydration can also be used to make powders and other products.
Dehydration occurs when the rate of water loss from a substance exceeds the rate of water uptake. When this happens, the cell or tissue will shrink and become dehydrated. Dehydration can be caused by exposure to high temperatures, low humidity, or wind.
Freeze-drying
Freeze-drying is a drying method where the water in the food is first frozen and then the water is removed in the form of vapor by lowering the pressure around the food. Freeze-drying can be done by either using a vacuum pump or by using nitrogen gas. Freeze-dried foods have a long shelf life because they do not contain any water that can support the growth of microorganisms.
Physical preservatives
Physical preservatives are used to prevent the growth of microorganisms or to slow down their growth. Some common physical preservatives are salt, sugar, vinegar, and alcohol.
Refrigeration
Refrigeration is a process of cooling a food to a temperature below its ambient temperature to prevent spoilage. The refrigerator is the most common form of this type of preservation. The lower temperature slows the growth of microorganisms and the rate of chemical reactions. Many microbes cannot reproduce below 40°F (4°C). Generally, food stored in the refrigerator should not be held longer than a few days.
Freezing
Freezing is a popular and convenient method of food preservation and one of the best ways to preserve food at home. When done correctly, freezing can preserve taste, texture, nutrients and color.
Freezing stops the growth of microorganisms by slowing down their metabolism. This happens because water expands when it freezes, which disrupts the cell walls of bacteria and other microorganisms. The freezing process also prevents the enzymes in fruits and vegetables from spoiling the food.
To freeze foods properly, wrap them tightly in airtight packaging. This will prevent freezer burn, which occurs when air dries out the food. It is also important to label all frozen foods with the date they were packaged so you can ensure they are used within a reasonable time frame. Most frozen foods will be safe to eat if they are kept frozen for six to nine months.
Natural preservatives
There are seven methods of food preservation: freezing, canning, pickling, drying, salting, smoking and pasteurization. Each method has its own pros and cons. Natural preservatives are becoming more popular as people become more aware of the harmful effects of chemicals.
Fermentation
Fermentation is a metabolic process that produces chemical changes in a substance. It occurs when enzymes break down a complex substance into simpler molecules. This process can preserve food and enhance its taste and nutritional value.
Fermentation has been used for centuries to preserve food. In fact, it is one of the oldest methods of food preservation. There are many different types of fermentation, and each one can change the flavor, texture, and nutritional value of food.
Benefits of fermentation
Fermentation can help to preserve food by:
-Preventing the growth of harmful bacteria
-Enhancing the flavor of food
-Making nutrients more bio available
-Increasing the shelf life of food
Pickling
Pickling is a process of preserving food in an acidic solution. The most common pickling solution is vinegar, but wine, citrus juice, and brine are also popular options. The food is typically placed in a jar or container and then submerged in the pickling solution.
Pickling is a great way to extend the shelf life of fruits, vegetables, meats, and fish. It can also add an extra layer of flavor to dishes. When pickling, it’s important to use fresh ingredients and sterile jars or containers. You should also carefully follow the recipe to ensure that the food is properly preserved.
Conclusion
Preservation method seven though there are other means of food preservation, these 7 methods are the most commonly used in the home. Each method has its own advantages and disadvantages that should be considered before using. Choose the method that best suits your needs and you will be able to enjoy home preserved foods for a long time.