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How to Make Dehydrated Vegetables and Fruits


Posted by Manny on March 25th, 2008

dried vegetablesSundried fish and fruits in the Philippines are common nowadays that is why Cebu has been famous for sundried delicacies like danggit and dried mangoes. But dried vegetables are not popular here maybe because we have an abundant supply of fresh vegetables. I’m not sure if it will be profitable selling dried vegetables because the time and materials spent on processing might not be feasible. But maybe with a little creativity by adding value to the product, you might sell it with a higher price than selling only fresh vegetables. For example, the food fish tilapia can be sold with a higher market value by converting it to marinated fish fillet, sausages or hamburger patties. Likewise you can also convert an ordinary vegetable like ampalaya or bitter melon into ampalaya chips by adding flavor like cheese or barbecue. Branding it as a healthy diet for diabetics, it might be a hit!

Sun drying of foods have been practiced by people since ancient times to preserve food in leaner times. There are many ways of food preservation like canning and pickling but solar drying is one of the cheapest way because you only need sunlight to petrify the food stuffs and a small investment in making the solar dryer. This summer is great for starting a sundried food business if you are thinking of having one.

Advantages of solar drying

  • Food in the cupboard for later use increases household food security.
  • It creates employment opportunities and a sustainable income.
  • Dried products improve family nutrition because fruit and vegetables contain high quantities of vitamins, minerals and fibre.
  • For diabetics dried fruit prepared without adding sugar is a healthy choice instead of desserts.
  • Dried fruit can be used in stews, soups and casseroles or enjoyed as snacks. It can also be added to cereals for breakfast or used in making ice cream and baked products.
  • It improves the bargaining position of farmers. Sometimes farmers sell at very low prices during the harvest season because they cannot store or preserve their surplus products.
  • People are encouraged to establish their own gardens.

Methods of drying

Sun drying

Drying in the sun is very economical. You only have to spread the produce on a suitable surface and let it dry in the sun.

Disadvantages

  • Somebody has to stay at home throughout the drying period to chase off domestic animals, to remove the produce when the weather becomes too windy and dusty, or when it rains.The dried product is often of poor quality as a result of grit and dirt.
  • The product is often unhygienic as a result of microorganisms and insects such as flies.

Solar drying

The technology and capital required to dry fruit and vegetables by solar dryers is basic and the entire operation can be completed in most kitchens. The structure can be very basic, e.g. a box frame covered with plastic sheeting.

Advantages of solar dryers

  • Drying is faster because inside the dryer it is warmer than outside.
  • Less risk of spoilage because of the speed of drying. (if the drying process is slow the fruit start to ferment and the product is spoilt).
  • The product is protected against flies, pests, rain and dust.
  • It is labour saving. The product can be left in the dryer overnight or during rain.
  • The quality of the product is better in terms of nutrients, hygiene and colour.

The drying process

Precautions

  • Cleanliness and hygiene are very important in the processing of dried fruit and vegetables.
  • To minimize the possibility of contamination, any person who is unwell or has infected wounds or sores, is ill with a gastric disorder or suffering from diarrhoea MUST BE EXCLUDED from the processing operations.
  • All cuts have to be covered with waterproof dressing.Raw materials contaminated by moulds must not be used in processing.

Predrying Treatments

Selection

  • Use only ripe, good-quality fruit and vegetables.
  • Select fruit and vegetables individually.
  • Discard rotted, damaged or diseased fruit and vegetables.
  • Remember, processing cannot improve poor-quality fruit or vegetables.

Washing

  • Clean all working surfaces before handling fruit or vegetables.
  • Water for cleaning must be treated with a household bleach solution.

Prepare the cleaning solution as follows:

– Pour 50 parts of clean water in a clean bucket (e.g. 20 litre).

– Add one part of any household bleach (e.g. 400 ml) containing chlorine

– For safety reasons plastic gloves should be worn when mixing the solution.

  • One bucketful of the treated water (20 litre) is enough for cleaning 20 kg of fruit.
  • Use a fresh cleaning solution every day.
  • Selected fruit and vegetables should be washed and scrubbed individually in the treated water, while plastic gloves should be worn.
  • Care must be taken to avoid breaking the skin of the fruit during cleaning and thereby contaminating the flesh.
  • Washed fruit and vegetables should be placed into a clean basket or bucket and taken to the peeling or blanching area.

Blanching

Before drying, all vegetables should be blanched in steam to halt the action of enzymes. However, blanching of fruit is optional. Steam blanching is recommended because it prevents the loss of some nutrients and the products being dried from adhering to each other. Do not underblanch, because the enzymes will not be inactivated totally and the dried vegetables will deteriorate during storage.
Procedure

Pour several centimeters of water into a large cooking pot that has a close-fitting lid. Heat the water to boiling and place over it, high enough to keep clear of the water, a wire rack or basket holding a layer of the vegetables (not more than 5 cm deep). Cover and let the vegetables steam for half the required time, then test to make sure all pieces are reached by the steam.

A sample from the centre of the layer should be wilted and feel soft and heated through when it has been properly blanched.

  • Remove the vegetables and spread them on paper toweling or clean cloth to remove excess moisture while you steam the next load. Cover with toweling while waiting for further treatment or before taking them to the drying trays.

Peeling

  • Hygiene is of utmost importance when peeling.
  • Peeling should not take place in the area where the raw materials are washed.
  • The area should be swept thoroughly and washed before handling the fruit.
  • Peeling knives and working surfaces should be cleaned in fresh bleach solution before use.
  • The operator should wash his/her hands and arms thoroughly with clean water and unperfumed soap.
  • Clean, sharp stainless steel knives must always be used.
  • Careful peeling with minimum removal of the flesh is important.
  • Peelings and seeds should be disposed of as soon as possible because they attract flies and other insects.
  • Peelings can be used as animal feed or as mulch, or be buried if there is no alternate use.

Cutting and slicing

  • Thickness of fruit pieces depends upon the kind of fruit being dried.
  • Thicker slices will dry at a slower rate than thinner pieces.
  • Very thin pieces tend to stick to the drying trays and will be difficult to remove.
  • Thicker pieces may not dry fully and may subsequently deteriorate after packing.
  • Packages of dried pieces of varying thickness appear relatively unattractive.
  • Cutting knives and working surface have to be cleaned with a bleach solution before use.
  • Slices should be placed in clean bowls which have been rinsed with clean water ready for loading onto the drying trays.
  • Before loading the trays, these have to be brushed clean and washed.

Dryers

A basic box-type low-cost solar dryer can be constructed at home or by village artisans. It is made of wire-mesh trays in a wooden framework surrounded by a clear plastic sheet. The solar cabinet dryer type has a surface of 10 m2 and is capable of drying 20 to 35 kg of fresh produce (depending on commodity) over a period of 3 to 4 days. Smaller portable models of the dryer can be constructed depending on available funds for the dryer, construction and the purpose of drying (home consumption or marketing).

For further information available on solar drying contact
Mr MD Brutsch at the University of Fort Hare
Tel: (040) 602 2131
Fax: (040) 653 1730
E-mail: mbrutsch@ufh.ac.za

Tray loading

  • Trays should be washed and cleaned to remove any fragments of dried fruit or contamination.
  • Start to load during slicing rather than waiting until all the fruit has been sliced or cut. (This reduces the problem of sticking together in the bowls and will allow drying to start as soon as possible.)
  • Lay the pieces of fruit on trays carefully and close to each other without overlapping to ensure the trays are loaded fully.
  • Keep flies away and load trays quickly and continuously.

Dryer loading

  • The dryer should be positioned in a level area unobscured by trees or buildings so that it is fully exposed to the sun throughout the day.
  • If the wind blows predominantly in one direction for long periods the dryer should be placed end-on to the wind. This will reduce the cooling effect of the wind blowing direct into the drying cabinet, lengthening drying times. It will also reduce the possibility of dust entering the cabinet.
  • Before loading, the inside of the drying cabinet should be swept clean and then wiped out with a clean, damp cloth.
  • The plastic covers outside should be brushed or washed clean of dust because dirty plastic will reduce dryer performance and increase drying times.
  • The doors should be closed immediately after each tray has been loaded and not left open until the next tray is fetched.
  • It is important to keep flies and other insects from entering the cabinet and off the fruit because of the risk of contamination.

Drying

  • 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.
  • 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. Rain will rapidly cool the dryer and this will result in a moisture film on the cover because of condensation. It will be some time before the dryer functions again after the sun breaks through. Therefore, protect the dryer from rain.
  • Under fine and sunny conditions the fruit slices should be dry after 2 full days in the dryer. However, it is essential to test slices. If the slices are not sufficiently dry, they will become mouldly in a short time. A test for dryness is conducted for specific products.
  • If the slices are not sufficiently dry, the process should be allowed to continue for 1 or 2 hours before checking again.
  • The final moisture content of dried fruit should be approximately 10 % (on a wet basis).

Unloading the dryer

  • When the fruit is considered to be dry, the dryer should be unloaded as soon as possible. This must not be carried out in the early morning because dew and high humidity overnight may cause condensation of moisture onto the fruit. The best time to unload is in the afternoon on a sunny day.
  • Trays should be removed from the dryer and taken to a clean and covered area for removal of the dried product.
  • The operator must wash his/her hands and ideally wear clean gloves when handling the fruit.
  • The dried fruit should be stored temporarily in clean dry baskets before packaging so that the product can cool down.

Packaging and storing

Packaging should be carried out immediately after unloading and cooling because the dried slices will reabsorb moisture and be susceptible to attack by insects and other pests.

Proper storage should take place in the absence of moisture, light and air.

  • The use of brown paper bags folded tightly and then placed inside plastic bags is recommended.
  • Store in small quantities to avoid large-scale contamination.
  • Pack carefully to avoid crushing the vegetables.
  • Glass containers are excellent, but these should be kept in a dark area.
  • Each bag or glass container should be marked clearly with labels containing the date of packaging.
  • The dried products must be stored in a cool, dry and clean area which is secure and protected against rodents and other pests.

Samples of Fruits and Vegetables You Can Sundry:

Dried Pumpkin leaves

Select fresh, tender leaves
Peel off the hairy outer skin
Wash in clean water
Steam blanch for 3 to 5 minutes
Place on trays ready for drying
Test for dryness: crumble easily

Dried Tomatoes

Select fresh ripe fruit
Wash in clean water
Slice into regular pieces (vertically)
Arrange the pieces on the tray for drying
Test for dryness: a handful will spring apart after squeezing

Dried Cabbage

Peel off the outer leaves
Wash in clean water
Cut the cabbage in two
Core
Chop into thin strands
Steam blanch for 5 to 8 minutes
Arrange on trays for drying. Spread evenly, not more than 1,5 cm deep.
Test for dryness: extremely tough ribs, the thin edges crumble.
Amaranthus sp.

Select young, tender and crisp leaves
Wash
Place loosely in a steaming basket and steam for 3 to 5 minutes or until well “wilted”
Spread sparsely on drying trays, keeping overlaps to a minimum
Test for dryness: crumble easily

Dried Sweet potatoes

Select firm, smooth potatoes
Wash
Steam in small quantity of water until the potatoes are just tender (30-40 minutes)
Peel
Slice into pieces (3-5 mm) or shred
Arrange the pieces on trays for drying
Test for dryness: slices extremely leathery, not pliable, shreds are brittle

Dried Carrots

Choose crisp, tender carrots without woodiness
(Not necessary to peel good, young carrots)
Steam until cooked through but not mushy (about 15-20 minutes depending on size)
Remove whiskers, tails and crowns
Cut into rings (2-3 mm) or shred
Arrange on trays for drying
Test for dryness: slices very tough, but can be bent. Shreds are brittle

Dried Beetroot

Choose small ones without woodiness
Leave 1 cm of the tops (they will bleed during precooking if the crown is cut)
Steam until cooked through (20-30 minutes)
Cool, trim roots and crowns and then peel
Shred with a coarse blade of a vegetable shredder (slices are not recommended because they take a long time to dry)
Spread thinly on trays for drying
Test for dryness: shreds are brittle
Pumpkin

Deep orange varieties with thick solid flesh make the best product
Cut in half (manageable pieces for peeling) and remove seeds and all pith
Shred with the coarse blade of a vegetable grater
Place in shallow layers in the basket, steam for 6 minutes
Arrange shreds on drying trays ready for drying
Test for dryness: shreds are brittle

Dried Green beans

Select young and tender stringless beans
Wash thoroughly
Steam for 2 to 3 minutes
Cut into short pieces or lengthwise
Arrange on trays for drying
Test for dryness: extremely tough ribs, the thin edge crumbles

Dried Herbs

This category includes celery leaves as well as other aromatic herbs such as parsley, basil, sage, tarragon, etc. All these should be dried at temperatures not exceeding 40 �C. (If it exceeds this temperature oils valued for flavour will be lost)

For best products

Water the herbs well the night before harvest.

Harvest on a sunny morning soon after the dew has dried and choose plants that are reaching flowering stage.

Harvest with sufficient stem, then strip off tougher leaves growing lower than 10 cm on the stalk.

Hold in small bunches by the stem and swish the leaves through cold water to remove any dust or soil.

Shake off the water and lay on absorbent towelling to allow all surface moisture to evaporate.

Cut off the handle stems and spread the leafed stalks one layer deep on the drying trays.

Put the dryer under a shade and cover the unventilated sides with a cloth to reduce the light on the herbs.

Turn the herbs several times to ensure even drying.

Test for dryness: crumble readily.

Dried Mangoes

Select firm, ripe mangoes
Wash with clean water
Peel
Cut into slices (2 – 3 mm thick)
Arrange on trays for loading into the dryer
Test for dryness: slices should be pliable, without sticking together

Dried Pineapples

Select firm, ripe fruit
Wash
Cut off the top and base
Peel
Cut into slices (2 – 3 mm thick)
Arrange on trays ready for loading into dryers
Test for dryness: slices should be pliable, without sticking together

Dried Bananas

Select good-quality fruit
Wash
Peel and remove the 2 tips
Slice into pieces (5 mm thick)
Arrange on trays for loading into dryer
Test for dryness: slices should be pliable, without sticking together

Dried Apples

Select good-quality fruit
Wash
Peel
Split
Core
Cut into regular slices (2 – 3 mm thick).
As you cut, dip the slices into lemon juice to retain the colour temporarily
Steam blanch for 5 minutes and remove excess moisture
Arrange slices on trays ready for drying
Test for dryness: leathery, no moisture when cut and squeezed

Source: www.nda.agric.za (South Africa Dept.of Agriculture)

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Posted by Manny

Manny Montala was an online entrepreneur who enjoys blogging about entrepreneurship and gathering information for his blog to help budding entrepreneurs. You can also reach him on twitter: http://twitter.com/mmontalaLike this post? Why not share it with your friends on facebook? Click the facebook share button!



5 Responses to “How to Make Dehydrated Vegetables and Fruits”

  1. Andrea says:

    Wow, thank you – the above article is excellent. Having grown beetroot for the first time I have a glut and want to store some for winter. The only options seem to be chutney or pickling, both of which are no good for cooking with. Not sure whether we have enough sun in the UK for this but oven drying should work just as well. Am looking forward to trying this. Thanks again.

  2. george says:

    January 9, 2010 Thank you so much for a very useful easy to learn inputs. speially on mangoes and banana dried

  3. blas says:

    how much is the solar drying?

  4. catherine says:

    we can use helium lights for drying foods.

  5. ruth says:

    what is the common desired moisture content of ampalaya?/

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