Drying as a means of Preserving

Drying offers an alternative way of preserving fruit, vegetables, meat and fish.

Dried fruit has almost the equivalent nutrient value of fresh fruit and is an important source of dietary fibre and potassium. It is low in sodium but high in vitamins and minerals. For those who do need to worry about sugar intake, while drying concentrates the natural sugar in the fruit, we tend to eat smaller quantities of dried fruit, so the total sugar and energy values are similar between dried and fresh fruit.

Tomatoes, chillies, peppers, as well as leafy green vegetables such as spinach, morog, cabbage and celery respond well to the drying process. Herbs also lend themselves to drying, as long as temperatures do not exceed 400 .

Types of dryers

You can spread your produce out to dry in the sun, but this means that someone has to be on hand to wave away flies and domestic animals and take it all in if it rains. Adequate hygiene is also more difficult to maintain like this, so some of the food will be contaminated.

To dry fruit in the oven, line the racks with cheesecloth and place fruit slices on top. The oven should be set at its lowest setting and the door should be left slightly open to allow any steam to escape.
There are dehydrators available for domestic kitchens, which range in cost from R350 for a biltong maker, R480 for a small dehydrator to nearly R20 000 for a very sophisticated machine. There are many different brands and they can be ordered online or from shops.

A biltong maker can be used to dry some kinds of vegetables

A greener alternative is to use a solar dryer. There are many designs of solar dryers available for DIY enthusiasts. Such a dryer can be a simple wooden box frame, covered in sheets of plastic, with wire-mesh trays. People have even used cardboard boxes, with some plastic wrap and some tape.

The advantages of solar dryers include drying faster, less risk of spoilage because of the speed of drying, protection from flies, dust and rain, as well as better finished product in terms of hygiene, nutrients and colour.

Method

When selecting your produce for drying, choose only ripe, good-quality fruit and vegetables, as drying cannot improve poor quality produce.

Preparing the produce

Ensure that the working surfaces have been well scrubbed beforehand and use clean cutlery and utensils. Prepare a bucket full of water to which household bleach has been added in proportion of 1 to 50. Use this water to individually washy the fruit or vegetables.

If you need to peel the produce, a clean, sharp stainless steel knife must always be used. Peelings and seeds should be disposed of as soon as possible because they attract flies and other insects.

When you are slicing, the thickness of the fruit pieces depends upon the kind of fruit being dried. Thicker slices will dry at a slower rate and may not dry fully, subsequently deteriorating after packing. Very thin pieces tend to stick to the drying trays and will be difficult to remove. Cutting knives and working surface have to be cleaned with a bleach solution before use.

It is a good idea to pre-treat fruits prior to drying, as this helps keep light-coloured fruits from darkening during drying and storage, it speeds the drying of fruits with tough skins and also enhances the destruction of potentially harmful bacteria.

Ascorbic acid can be used: stir 2 1/2 tablespoons (34 grams) of pure ascorbic acid crystals into one litre of cold water. Vitamin C tablets can be crushed and used (six 500 milligram tablets equal one teaspoon ascorbic acid). One litre of solution treats about 10 litres of cut fruit. Cut your peeled fruit directly into the ascorbic acid solution, soak for ten minutes, remove with a slotted spoon and drain well. Citric acid or lemon juice can also be used to pre-treat fruit.

Pre-treat vegetables by steam blanching them. Use a steamer or place them in a wire sieve over boiling water. Steam until a sample from the centre of the layer is wilted and feels soft and heated through.

Lay the pieces of fruit or vegetables on trays carefully and close to each other without overlapping to ensure the trays are loaded fully.

During drying

If you are using a solar dryer, it should be positioned in a level area far from trees or buildings, so that it is fully exposed to the sun throughout the day.

During the first few hours of drying, particularly during very hot and sunny weather, fruit may dry at such a rate that moisture condenses on the inside of the plastic covers, if your solar dryer does not have sufficient through-flow of air.

This can be avoided by opening the loading doors slightly (20 mm) to improve air circulation. The gap should, however, be covered with mosquito mesh.

Doors should be kept open for a minimum period of time and closed again as soon as the weather becomes cloudy.

In poor weather drying will stop, so protect the dryer from rain.

Under fine and sunny conditions the fruit slices should be dry after two full days in the dryer. However, it is essential to test slices. If the slices are not sufficiently dry, they will become mouldy in a short time. Dried fruits should be leathery and pliable. To test foods for dryness, remove a few pieces and let them cool to room temperature. When warm or hot, fruits seem more soft, moist and pliable than they actually are. Squeeze a handful of the fruit. If no moisture is left on the hand and pieces spring apart when released, they are dry. If the slices are not sufficiently dry, the process should be allowed to continue for one or two hours before checking again. It is best to unload the dryer after the morning dew has dried off. The dried fruit should be stored temporarily in clean dry baskets before packaging so that the product can cool down.

Conditioning

When drying is complete, some pieces will be moister than others due to their size and placement during drying. Conditioning is a process used to evenly distribute the minimal residual moisture throughout all pieces. This reduces the chance of spoilage, especially from mold. To condition, place cooled, dried fruit loosely in large plastic or glass containers, about two-thirds full. Lightly cover and store in a warm, dry, well-ventilated place for four to ten days. Stir or shake containers daily to separate pieces. If beads of moisture form inside, return food to drying trays for further drying, then repeat the conditioning step.

Dried peaches.

Storage

Ensure food is thoroughly cool before storing. For best retention of nutrients in dried foods, it is best to store them in a cool, dark, dry place and use within a year.
Store in small quantities in glass bottles or brown paper bags. If you are using glass containers, place them in a dark corner. Check supplies frequently for contamination or dampness. Properly stored, dried fruits keep well for six to 12 months.

Use in cooking

To reconstitute fruit for use in a cooked dish place it in a bowl and cover with boiling water. Soak until tender and liquid is absorbed. Thinly sliced fruits may not require soaking before using in cooked dishes.

Soak all vegetables except greens in cold water until they are nearly restored to their original texture, using only enough water to cover and always cook in the soaking water. Cover greens with enough boiling water to cover and simmer until tender.

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