G17 Drying fruit and vegetables

Food SecurityFood Processing
  • When drying food, particularly if it is to be sold, it is important to keep food as clean as possible. To preserve the colour, fruit pieces should be dipped into boiling water containing lemon juice and preservative, if available. Vegetable pieces should be dipped in boiling water containing salt and preservative, if available.
  • Dried fruit can be eaten directly. It can also be softened by soaking with water. Good quality fruit may also become a cash crop suitable for marketing and export. Dried vegetables can be added to stews and soups for flavouring.
  • Many vegetables and fruits can also be preserved by drying. Tomatoes, herbs, mangoes and onions are examples of crops which can easily be dried and stored. Drying is a way of preserving good harvests instead of selling when market prices are low.
  • When fully dry, store in airtight containers or plastic bags. Check regularly for mould.  

Discussion

  • Discuss traditional methods of drying foods and their advantages and disadvantages. Would using a solar drier bring any advantages?
  • What preservative is available in chemists? Potassium metabisulphite is recommended.
  • Build a solar tent drier with a drying frame of wire raised about half a metre above the ground. Use clear plastic on the sunny side and ends, and black plastic on the shady side. One end is left loose for entry and closed with stones or brick. The sides can be rolled over a pole to control the temperature.
  • Here is an example of how to dry mangoes. If they are dried well and have a good colour, dried mangoes can often be sold in markets or to exporters: 
    • Peel good quality, large, half-ripe mangoes and cut into thin slices (6–8 mm thick) with a stainless steel knife.
    • Soak the slices in a bowl containing one litre of boiling water, 700–800 grams of sugar (five small teacups), two large spoons of lemon juice and three grams (one heaped teaspoon or soda bottle top) of potassium metabisulphite (a preservative which can be bought in chemists).
    • After 18 hours, drain the slices and dry them. 
    • Store the dried fruit in plastic bags. 
  • For vegetables, it is recommended to dip sliced vegetables into a pan containing one litre of boiling water, 50 grams (two large spoons) of salt and three grams of potassium metabisulphite. Place in a thin layer to dry on the rack.
  • Experiment with fruit and vegetables available locally and find which method works best.