Food Preservation

 

Do you love to open your refrigerator and look for your favorite food, snacks, fruits etc, in them? Have you ever wondered what the refrigerator is used for? If you would have asked elders they would have told you, refrigerators are to preserve and keep food safe, preventing it from getting spoilt.

Have you wondered what our ancestors would have done in old days when there were no refrigerators? Fruits and vegetables are not available throughout the year, they are seasonal, so we adopted various ways to preserve our food such that they may be available to us even when they are not growing in a season. These methods to preserve our food are called 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. Preservation process also ensures that there is no discoloration or aging. Preservation also involves sealing to prevent re-entry of microbes. Thus we understand that food preservation ensures that food remains in a state where it is, i.e.:

  • Not contaminated by pathogenic organisms or chemicals.
  • Does not lose optimum qualities of color, texture, flavor and nutritive value.
 

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 ovens. Meat and fruits like apples, apricots and grapes are dried using this method. 

Freezing is keeping prepared food stuff in cold storage. Potatoes can be stored in dark rooms but potato preparations need to be frozen. 

Smoking is the process that cooks, flavors and preserves food exposing it to the smoke from burning wood. Smoke is antimicrobial and antioxidant and most often meats and fish are smoked. Smoking as a preservative is believed to enhance 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 preserving dry fruits.

Salting and Pickling: Salting, also known as curing removes moisture from foods. Pickling means preserving food in brine which is salt solution or marinating in vinegar (acetic acid). In Asia, oil is used to preserve food. There are various methods of pickling like chemical pickling and fermentation pickling.

Sugar is used in syrup form to preserve fruits. The material to be preserved is cooked in the sugar solution till crystallization takes place like candied peel and ginger. Another use is for glazed fruit that gets superficial coating of sugar syrup.

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.

With each method food is preserved saved and kept fresh for another day, week or month. Any food can be saved and stored if the proper technique for the food product is used correctly. Before beginning any food preservation technique, it is important to thoroughly study and undersatnd the shelf life and correct methods to be used.