The following are ways of preserving food EXCEPT

Analyze the question: We need the option that is NOT a method of food preservation. Four of the five are standard preservation methods.

Explain the concept: Food preservation prevents spoilage by stopping or slowing the growth of microorganisms (bacteria, fungi) and the action of enzymes. Common methods include:

• Canning: food is heated and sealed in airtight containers, so microbes cannot enter.
• Drying: removes the water microbes need to grow (e.g., dried fish, beans, crayfish).
• Freezing: low temperatures slow or stop microbial growth (e.g., frozen meat in a freezer).
• Salting: salt draws water out of microbial cells by osmosis (e.g., salted fish, beef).
• Others: smoking, refrigeration, pickling, use of chemical preservatives, and irradiation.

Step-by-step solution:

1. Canning, drying, freezing, salting: all are recognised preservation methods.
2. Boiling: this is mainly a method of cooking. It kills many microbes at the time, but it gives no lasting protection. Boiled food left in the open is quickly recontaminated and spoils within hours or a day, unless it is then sealed, as in canning. So boiling by itself is not classed as a preservation method.

Boiling is therefore the odd one out.

Answer: A. boiling

Exam tip: In "EXCEPT" questions, look for the option that is a cooking or preparation method rather than a storage method. Real preservation methods keep food safe over a long time by removing water, lowering temperature, adding salt, or sealing it away from air and microbes.