Hint: Food preservation is defined as a term that means increasing the shelf life of the food, in other words, it can be defined as the storage of food in such a way that it does not spoil in a shorter time. Many methods and chemicals are used for the preservation of foods.
In order to slow down the spoilage process of our food and so in order to keep the food fresh for a longer period, many preservation methods have been discovered and are applied to foods.
Different ancient methods of preservation of food are as follows:
It is one of the oldest and the ancient techniques that are used to preserve or process by food products. It is naturally performed by exposing the food particles to sunlight to dry them. Drying leads in the evaporation of moisture and also water content from food which in turn prevents the invasion and growth of microorganisms in food. Drying can also be performed by using hot air. It is employed mainly for food grains like wheat,
2.Smoking: Foods for example meat and fish are processed, preserved, and flavoured by the use of smoke. This is performed in big smokehouses. The food processing and the combination of smoke with the aroma of hydrocarbons generated from the smoke processes enhance and increase the taste of food.
3.Pickling: It is defined as a process of preserving food in an antimicrobial liquid that is fit for human and animal consumption. Pickling can be divided into two types: fermentation and thermal pickling:
In fermentation pickling, bacteria that occurs in a liquid produces organic preservation agents that prevent food spoilage for a longer time.
In chemical pickling, the food is preserved in an edible liquid which is mostly named as vegetable oil, and many other types of oils that destroy microbes.
Hence, the correct answer is option (D)
Note: Nowadays, there are many more processes that are needed for preservation one of them is defined as vacuum packaging, as food is stored in packets from which all the air is removed leaving a vacuum, as this is an effective method for food preservation.