Food preservation is the scientific method that involves stopping or slowing down the deterioration of food, enabling it to be suitable for future consumption. This process maintains the food's quality, consumability, and nutritional value. It includes inhibiting the growth of fungi, bacteria, and other microorganisms. The procedure also guarantees no discoloration or aging occurs. Preservation also includes sealing methods to block the re-entry of microbes. In essence, food preservation ensures that food:
- Is not tainted by harmful organisms or chemicals
- Retains its prime characteristics of color, texture, flavor, and nutritional value
Salting and Pickling
For many centuries, the techniques of pickling and salting have been utilized for food preservation. The method of pickling was first employed by native Indians in 2030 BCE to keep cucumbers fresh, while salting has been traced back to around 6000 BC. Both methods deter the activities of bacteria and other microorganisms, thereby preventing food from spoiling.
Salting extracts moisture from food, creating an environment that inhibits bacterial growth. This method is predominantly used to preserve a wide range of foods, from vegetables like beans, corn, and cabbages to fruits such as pears and apples, as well as butter, fish, cheese, meat, and bread products.
On the other hand, pickling involves establishing an acidic environment that effectively eliminates bacteria. This can be done by combining common salt and water (to form brine), which results in lactic acid, or a mixture of vinegar (acetic acid), spices, and oil.
Freezing is one of the most straightforward, handy, and time-efficient methods to prolong the freshness of produce. The severe cold associated with freezing halts the progression of potentially harmful microorganisms, thus minimizing food decay.
You can slice and freeze fruits and vegetables at their ripest, yielding maximum nutritional value, and incorporate them into meals throughout the year. To avoid the common browning and freezer burn when herbs are frozen alone, fresh herbs can be conserved by freezing them in vegetable oil. When combined with seasonal or frozen vegetables, this strategy provides an uncomplicated approach to keeping herbs ready for use in winter recipes.
Lyophilization, more commonly known as freeze-drying, is a top-notch and health-conscious method of food preservation. It effectively removes up to 99% of water from food items. The process of freeze-drying involves three stages:
- Initial freezing
- Drying under high-pressure vacuum
- A final round of drying
Initially, the temperature of the food is reduced below its freezing point. Then, a high-pressure vacuum extracts moisture from the food, which is converted into ice via sublimation for effortless removal.
The last step consists of a slow temperature increase to eliminate residual moisture, ensuring the food's structure remains intact. The food is then stored for future rehydration and consumption. Unlike regular freezing, freeze-drying actively extracts moisture from food, thereby preventing the growth of bacteria and other microbes. This characteristic significantly enhances the shelf life of the food.
Food irradiation involves using ionizing radiation to extend the shelf life of food. It also kills bacteria, insects, and other parasites present within or on food items. Irradiation begins by placing the food into a chamber where it undergoes an intense and controlled dose of ionizing radiation. This process is intended to kill off any living organisms in and on the food, thereby eliminating potential pathogens.
Food irradiation has been approved by the World Health Organization (WHO) and the United States Food and Drug Administration (FDA). However, it remains controversial due to concerns about long-term health effects.
It is primarily used in industries that process meat and poultry products and some fruits and vegetables. You can check an article from TDI Packsys to decipher the myth about Food irradiation.
By Leaving Out Air
Preservation through air exclusion is a method applied to food. The most common way of doing this is canning. Food is stored in airtight containers to keep air out. Canning is a versatile method, applicable to a wide range of foods. While buying pre-canned goods can sometimes be more cost-effective than home preservation, the latter can become expensive due to the need to purchase the food and the necessary equipment such as glass jars, rubber seals, and a pressure cooker.
However, when produce is abundant, it's advisable to can the excess to avoid wastage. Stored canned items should be kept in a cool, dry location, with each jar accurately labeled for easy identification. Regular cleaning and organizing storage shelves are recommended for easy access and visibility of cans and jars. While metal is the typical material associated with cans, any container that can be sealed - including glass jars, plastic pouches, or foil packets - can serve the same purpose.
A variety of food preservation methods exist. The most effective one for you hinges on your specific requirements and liking. Before preserving food, conduct an exhaustive study to ensure you opt for the most appropriate technique for your particular scenario.