Preservation of Fruits and Vegetables

Subject: Home Science — Topic: Foods and Nutrition (Age: 11, Kenya)

Why preserve food? ☑️ Fruits and vegetables go bad quickly. Preservation helps us:

• Keep food safe to eat for longer.
• Save money and avoid waste.
• Enjoy fruits and vegetables even when they are out of season (e.g., mangoes, avocadoes).
• Help your family have food during school holidays or dry seasons.

Common Kenyan fruits & vegetables (examples)

Mango, banana, avocado, pineapple, oranges, tomatoes, sukuma wiki (kale), spinach, carrots, cabbage, onions, potatoes, sweet potatoes.

Signs that a fruit or vegetable is spoiling

• Bad smell or sour smell.
• Soft, mushy parts or dark spots.
• Mold (white, green or black fuzzy patches).
• Liquid leaking from the fruit or vegetable.

Main methods of preservation

1. Drying (Sun-drying or solar dryer) ☀️

Drying removes water so microorganisms cannot grow. Good for mango slices, tomatoes, sukuma wiki (kale), and carrots.

Simple steps (sun drying):

1. Wash and cut food into thin pieces.
2. Blanch leafy vegetables for 1–2 minutes in boiling water, then cool in clean water — this keeps colour.
3. Place on clean trays in the sun, cover with a fine net to stop flies.
4. Bring trays inside at night. Dry until hard and brittle or leathery.
5. Store in clean, dry airtight jars or tins.

2. Refrigeration and freezing ❄️🧊

Use the fridge to keep food fresh for days and the freezer for months. Good for cut fruits, peas, spinach, and tomatoes.

• Keep fridge at about 1–4°C and freezer at −18°C (if available).
• Blanch vegetables before freezing to keep colour and vitamins.
• Use clean, airtight bags or containers to avoid freezer burn.

3. Canning and bottling (making jams, juices, or canned tomatoes) 🫙

Heat and seal food in clean jars. This kills bacteria and keeps food safe for months.

Example: Mango jam — fruit, sugar, and a little lemon juice cooked and poured into sterilised bottles.

4. Pickling and fermentation 🧂

Use salt, vinegar or natural fermentation to preserve. Good for vegetables like carrots, cabbage, and cucumbers.

• Pickles: use clean jars and enough vinegar or salt solution to cover the vegetables.
• Fermentation: make sure containers are clean and the vegetables stay under brine (water + salt).

5. Storing in cool dark places (traditional methods)

Some roots (potatoes, sweet potatoes) last longer if kept in a cool, dark, ventilated store or pit. Use dry sand or ash around bulbs (e.g., onions) to keep them dry.

6. Smoking and salting 🔥🧂

Smoking can preserve some vegetables and fruits in rural settings. Salting is useful for some vegetables and reduces water activity.

Food safety tips — keep it safe!

• Wash your hands and tools before starting.
• Use clean water and clean containers.
• Remove spoiled parts before preserving.
• Label containers with the date. Eat older food first.
• When in doubt (bad smell, odd colour), throw it away.

Quick classroom / home activity

Make sun-dried tomato chips:

1. Wash and slice tomatoes thinly.
2. Sprinkle a little salt (optional) and place on a clean tray covered with netting.
3. Dry in the sun for 2–4 days, turning once a day.
4. Store in a clean jar with a tight lid.

Short glossary

Blanch — dip food in boiling water for a short time, then cool quickly.
Fermentation — friendly microbes change food (e.g., sour cabbage).
Brine — salty water used to cover vegetables.
Freeze/Freezer burn — when frozen food dries out from air exposure.

Mini quiz (check your learning)

1. Name two Kenyan fruits you can sun-dry.
2. Why do we blanch vegetables before freezing?
3. What should you do if a jar of preserved food smells bad?

Useful tip: In areas without electricity, solar dryers and drying racks are cheap and work well. Ask an adult before using heat or hot water.