Food is a means of nutrients through which our body acquires its needs in the form of minerals and ions, energy in order to carry different functionalities of life. The process of acquiring these nutrients is called nutrition. Our food mainly consists of polymers such as proteins, carbohydrates, fats, and nucleic acids. According to a calculation in April 2019 the estimated population of earth is above 7.7 billion. So, it is not easy to fetch anyone in any part of the world fresh food at any time. Therefore, steps must be taken to increase the shelf life of food in order to maintain its quality. This also keeps away food from microbial decay. here we will talk about the preservation of food.
So in order to take the steps for the preservation of food we should understand what factors play a role in the preservation of food? The most important part of our diet is water which apparently doesn’t give us energy but plays an important role in texture, quality, the taste of food. It is not always possible to judge the quality of food through smell and taste because these factors change with person to person, nation to nation and place to place. The best technique to judge the quality of food is water activity (aw) The term related to show the relative concentration of water in food is water activity.
It is necessary to know that different diets and fruits have different water activity.
Most bacteria can grow in food and fruits having water activity up to 0.8 while fungi can grow on bread or diets having aw of about 0.7 so by lowering of water activity of such fruits and foods wisely to a certain level may protect them from microbial decay. Methods like freezing (cooling) and addition of salts, sugar, etc use the same strategy in order to preserve it. However, there are some techniques to increase the shelf life of foods.
Pasteurization-Preservation of Food
It is the method to preserve the dairy products esp milk. In this technique, milk is boiled to about 70 or 63-degree centigrade for about 15 seconds. This method kills the undesired microorganisms and denatures the enzymes within the milk thus enhancing its quality and shelf life.
Cooling or freezing-Preservation of Food
It is one of the most ancient techniques which is used to preserve food for centuries. In this method, the food is cooled to about 0-degree centigrade. This cooling not only deactivates the enzymes but also it limits, the extra water molecules in food which grow the microorganisms.
Drying-Preservation of Food
Certain food products such as milk can be preserved by drying. In this method, techniques are used to eliminate water from the food whether it is boiling or keeping in the sun.
Boiling is used for milk to eliminate water. Grapes are converted into raisins and apricot and peach are dried to get their respective dry fruits.
Addition of Salts or Salting
It is also a very ancient method of preservation of food. In this method, salts are added to meats and meat products to limit the concentration of water and thus limiting enzymatic reactions and microbial decay. It can mildly affect the taste of food. For example, meat was preserved by our ancestors for the whole year through this method.
One of the methods which are used these days is canning. In this method the meat, poultry products are packed in metal jars which protect them from the outer environment and also these jars are heated and sterilized in order to kill microorganisms thus increasing the life of food. This process has one more advantage that the product can be transport easily.