Question

Discuss the classification of food based on shelf life. Take an example of a semi-perishable food and explain various methods of increasing its shelf life.

Answer 1

Foods are classified by how long they remain fit to eat at room temperature:

1. Perishable: Remain fresh for a few hours to about 1–2 days; examples include milk, meat and green leafy vegetables.
2. Semi-perishable: Remain fresh for about 5–7 days; examples include some fruits and vegetables.
3. Non-perishable: Remain fresh for more than a month; examples include grains, sugar, oil and pulses.

Example: tomatoes (a semi-perishable food)

1. Choose sound tomatoes and remove damaged or spoiled ones to limit the spread of spoilage.
2. Keep them in a clean, cool, dry place; refrigeration can slow spoilage.
3. Preserve them by cooking into a puree or sauce and storing it hygienically. Heat treatment and, where permitted, an approved preservative used within prescribed limits can further extend shelf life.
4. Drying or other suitable processing can also reduce moisture and slow spoilage.