Drying is one of the oldest, easiest and cheapest methods of preserving food.
Several fruits, vegetables and herbs can be stored this way with great success for later use in soup, stews and puddings.
Fruit and vegetables that are dried and stored carefully retain most of their nutritional value. As moisture levels decrease during the drying process, fruit sugar (fructose) and mineral trace elements like phosphor, copper, potassium and iron become more concentrated, which makes sense if you take into account that 5 kg to 6 kg of fresh fruit delivers about 1 kg of dried fruit.
Dried products also take up less space as compared to when it is preserved in other ways.
- Only use good quality produce – drying won’t enhance quality.
- Harvest fruit when it is properly ripe, but not overripe.
- Don’t use fruit that fell from the tree, because that would cause bruising, leaving black marks when it is dried.
- Handle vegetables gently and only harvest those that are young.
- Harvest the produce during the early morning when it is still cool, on a day that is expected to be sunny and warm.
- Start processing your produce immediately.
- Wash the fruit, if necessary, and use it whole, skin included.
- Otherwise, you can peel and seed the produce and cut them in halves, quarters, rings or smaller pieces. Small, relatively thin pieces of the same size usually work best for drying.
- The faster you dry the vegetables and fruit, the better the colour. If the tempo of moisture evaporation at the beginning of the process is too quick, a hard crust may form and the produce might be dry on the outside, but still moist on the inside. This may lead to mould.
Depending on the type of produce, it can be treated with one or several of the following methods.
Salt or ascorbic acid:
When fruit and vegetables are prepared for blanching or the sulphur process, they must be treated against discolouration.
Place the produce in a solution of 150 g of salt per 5 litres of water for a few minutes and drain it afterwards.
You can also sprinkle a solution of 10 ml of ascorbic acid dissolved in 500 ml of water over the produce. (A stronger solution of 25 ml ascorbic acid to 500 ml of water should be used for apples.)
Blanching conserves the colour, delays spoiling and creates small crevices in the peel of certain products, which speeds up the drying process.
- This method is for producte that can be blanched in water. With regards to vegetables, this process is not applicable to beetroot, onions, chives, garlic, mushrooms, capsicum and tomatoes.
- Place the vegetables or fruit you want to blanche in a wire basket or a cheese cloth and dip it into a pot of fast boiling water.
- Immerse it for 5 to 6 minutes in the water until it is cooked thoroughly.
- Calculate the time from when the water starts boiling after you dip the product into the water. All vegetables and fruit don’t need the same amount of time.
- Cool the product immediately by dipping it into ice water.
- Place the drained vegetables or fruit between two layers of paper towels and pat it dry gently.
- Place the produce in a wire sieve or basket, colander or cheese cloth on a shelf to keep it about 5 cm above some fast boiling water in a large pot.
- Cover with a lid to allow the steam to circulate between the pieces of produce for about 10 minutes.
- Don’t let the moisture that condensate on the lid and drip on the produce.
- By treating produce with sulphur smoke before drying, you kill mould/fungi, dangerous micro-organisms, as well as preventing browning, speeding up the drying process and increasing storage time. Unsulphured fruit taste better raw than treated fruit.
- Use a tight container like a cupboard or box of roughly 1 m x 1 m x 1.5 m. There must be a small amount of air circulation, otherwise the sulphur won’t burn.
- If you use a cupboard, it would be best if it has slits that allow you to insert and remove shelves.
- Don’t use galvanised metal – it reacts with sulphur to produce a compound that makes dried produce harmful.
- Place rock sulphur and some kindling in a sturdy iron pan in the bottom of the cupboard. Depending on the product, you can burn 500 g to 1.5 kg of sulphur per 3 m3 space in the cupboard (1 m x 1 m x 1.5 m = 1.5m3). For example, you need 750 g of sulphur for apricots, 1 kg for peaches and 1.5 kg for pears.
- You can ignite the sulphur with a blow torch or by igniting a bit of methylated spirits after you put in the wooden shelves.
- If you sprinkle a bit of flowers of sulphur over, the sulphur would ignite easily. Close the lid properly and allow the produce to remain in the fumes for two to three hours.
- Sodium metabisulfite (Na2S2O5) is available at chemists and is also available as a tablet. It acts as a preventative measure against the formation of bad bacteria as well as yeast and fungi (mould).
- You can make the following 10%-solution that can be stored for up to 6 months in a tightly closed bottle: Dissolve 100 g of sodium metabisulfite in 500 ml of warm water and dilute the solution with cold water up to 1 litre. 5 ml of this solution is equal to 0.44 g in tablet form.
- The solution can also be used to sterilise bottles and jars. Pour a bit of the solution in a clean bottle or jar, shake it and rinse the bottle afterwards with boiling water. The solution can be re-used for the same purpose.
- Use 1 ml of this 10% sodium metabisulfite solution per 1 litre of cold water that is needed dip the vegetables in for a few minutes after blanching. Drain well afterwards.
- Otherwise, make up a solution of 1 ml sodium metabisulfite per 2 litres of water per 2 kg of blanched vegetables.
- Heat the solution to boiling point and place the vegetables in the solution for 5 to 6 minutes until it is heated through.
- This method combines blanching and treating produce with sulphur.
There are two methods to dry your produce – outdoors in the sun or in a draft in the shade, and indoors in an oven or drying cabinet.
- You need bright sunlight, warm day temperatures and low humidity when the produce is dried to get a good result.
- Vegetables and fruit that are high in sugar and starch are the best options for drying.
- Trays are commonly used when drying produce in the sun. It should not be too large, otherwise it might be more difficult to turn the produce because you can’t reach the ones in the middle.
- These trays can be made from wooden planks, cane, gauze or chicken mesh.
- A wooden plank surface of about 2.5 m x 1 m with a wooden frame is a comfortable size.
- It works well for the drying of fruit like apricots, peaches, pears, figs and apples.
- A cane frame is durable and works well for fruit that can roll down easily like figs or prunes, or that stick easily.
- You can tighten whole split cane, with the round ends facing up, with a thin wire on a framework of about 2.5 m x 1 m.
• To dry vegetables, you can span mousseline or cheese cloth tightly over a frame.
- Stretch your chicken mesh over a frame mounted on a foot piece.
- You can stack the several of these on top of each other, while leaving space for good ventilation, to allow you to dry more fruit and vegetables in a small space.
- The produce must be laid out in a single layer and should be placed at an angle towards the sun on a roof or your lawn for maximum exposure.
- The trays should be covered with mosquito net or gauze to protect the produce against insects and dust.
- You should stack and cover the trays overnight or during rainy weather.
Drying produce indoors in the oven or microwave oven, or in a drying cabinet, is a faster method since the drying process is not influenced by the weather.
In the oven:
- The produce can be dried for 4 to 6 hours in an oven heated to 60º C.
- Another method is to start the drying process at 50ºC, then gradually increasing the temperature to 70º C and when the vegetables are almost dry, finishing the process at 60º C.
- Leave the oven’s door slightly open.
- Products like apples, sweet peppers and onions can be cut into rings, threaded onto a wooden skewer and placed on an oven rack for drying.
- You can also span a mousseline cloth over the oven rack and place the produce on top of it.
- Always start the drying process with the cut side of the produce facing up.
- Turn the produce after a while and ensure the produce isn’t touching.
- The produce must be cooled down for at least 12 hours at room temperature before you pack them.
- Produce in a drying cabinet is exposed to a stream of warm, dry air produced by a fan and heater that absorbs and carries moisture away.
- The drying temperature must be between 50ºC and 70º C.
- An elevated drying cabinet with a foot piece can be self-manufactured.
- The foot piece must be high enough to enable the cabinet to be safely placed above the heat source, like a heater.
- The cabinet must be open on the bottom so the heat can enter the cabinet.
- There should also be a ventilation opening so the air can escape.
- The cabinet should also have slots where the drying trays can be slid in, with enough space between to ensure the circulation of warm air.
- Spread the fruit or vegetables out in a 2 cm layer on the drying tray.
- Place the produce on a cheese cloth or mousseline to prevent it from falling through, if necessary.
- It takes about 3days to dry fruit and vegetables with a fan.
- If some of the moisture is removed and the produce is placed in a low oven or in the sun, the drying time can be decreased to 2 days.
TEST FOR DRYNESS
If you are unsure about whether your vegetables are dried properly, spread them on a baking tray in a thin layer and heat for 15 minutes in an oven at 90º C. To test whether it is dried out completely, place a small amount of the dried vegetables in a tightly sealed glass container. If any moisture collects in the container after 24 hours, it’s not dried properly. Dry again for a while and repeat the test.
Another method is to place the dried produce in a glass container along with a biscuit. If the biscuit gets soft after a while, the produce needs more drying.
To test whether fruit are fully dried, squeeze a handful together. They should not stick together and should fall loose when you let go.
Damp fruit can get mouldy or turn sour. To dry them again, dip the fruit in boiled water and repeat the drying process.
Spread dried vegetables out in a thin layer on a baking tray to keep it insect free. Place in a cold oven and heat it up to 180º C. Let it cool and package in cardboard boxes or paper bags.
Dried fruit should not be stored immediately. Heap the fruit in boxes to ensure any moisture is dispersed evenly. Then you can store them in appropriate containers.
*The recipes were translated and adapted from Lekker vir later PLUS, written by Annette Human and published by Human and Rousseau.
If you want to read more on drying specific and indigenous fruit and vegetables, click here.