Food Preservation Techniques: Killing the Microbes and Making them Inactive

Food preservation is the process of treating and handling food in such a way that it prevents spoilage, extends its shelf life, and maintains its nutritional value. One of the main objectives of food preservation is to inhibit the growth and activity of microorganisms that can cause food spoilage and pose a risk to human health.

1. Killing the Microbes:
One technique used in food preservation is to kill the microbes present in the food. This is typically achieved through various methods such as:

- Heat Treatment: High temperatures can kill most microorganisms. Techniques like boiling, pasteurization, and sterilization involve exposing the food to heat to eliminate or significantly reduce microbial populations. For example, canning involves heating food to a high temperature and sealing it in a sterile container, effectively killing any microbes present.

- Irradiation: In this method, food is exposed to ionizing radiation, such as gamma rays, X-rays, or electron beams. This radiation damages the DNA or other cellular components of microorganisms, rendering them unable to reproduce or cause harm. Irradiation can be used to kill or reduce the population of bacteria, viruses, molds, and parasites.

- Chemical Preservation: Some chemicals have antimicrobial properties and can be used to kill or inhibit the growth of microorganisms. For instance, food additives like preservatives (e.g., salt, sugar, vinegar) and synthetic antimicrobial agents (e.g., sodium benzoate, potassium sorbate) are commonly used to prevent spoilage.

2. Making Microbes Inactive:
Another technique employed in food preservation is to make the microbes inactive rather than killing them. This includes methods such as:

- Freezing: Low temperatures can slow down or halt the growth of microorganisms. Freezing food at temperatures below 0°C inhibits microbial activity, preventing spoilage. However, it is important to note that freezing does not kill all microorganisms; it only puts them in a dormant state. When the food is thawed, these microbes can become active again.

- Drying: Removing moisture from food can also inhibit microbial growth. Dehydration methods like sun drying, air drying, or using specialized machines can reduce the water content of food, making it less hospitable for microbial activity. Without sufficient moisture, microorganisms cannot grow and spoil the food.

Conclusion:
In summary, the food preservation process involves both killing the microbes and making them inactive. Killing the microbes is achieved through techniques like heat treatment, irradiation, and chemical preservation. On the other hand, making the microbes inactive is accomplished through methods such as freezing and drying. These preservation techniques help prevent spoilage, extend the shelf life of food, and ensure its safety and quality.

You can preserve food by either killing all the microbes(which contribute to degradation of food) or by making them inactive, so that they don't harm or spoil the food material. Hence, option c is justified.
For example:-
• Killing microbes by pasteurisation, vinegar addition, etc.
• Making microbes inactive by nitrogen- storage, freezing food below 0 degrees Celsius, etc.