|Better Farming Series 44 - Processing of Cassava and Sweet Potatoes for Animal Feeding (FAO, 1995, 49 p.)|
|Processing of cassava into dried chips|
62. It is not difficult to produce cassava chips. Here are some things that you should know about how to dry cassava roots.
63. You do not need many things to produce cassava chips. You need
- enough cassava roots on your farm;
- knives or a shredder;
- a place to dry the chips;
- your time.
64. You must try to prepare good quality chips. Good quality chips can be kept for longer.
65. To get good quality chips, you must start processing immediately after harvest.
66. Do not use any tubers that are damaged or spoiled. Such tubers must be removed before you start processing.
67. When you prepare dried chips, there are three major steps in the process;
- preparation of the roots;
- chopping or shredding of the roots;
- drying of the chips.
68. First of all, you must clean the roots in water to remove any soil clinging to them.
clean the roots
69. Then you must remove the peel of the roots. If you do not remove the peel, the chips will be brownish in colour and will contain a lot of cyanide.
70. If you zremove the peel, you will lose 10 to 15 percent of the root weight. But the colour of the chips will be whiter and they will have more market value.
Zremove the peel
71. If you are planning to use the chips for feeding animals on your farm, the brownish colour will not matter. Then you may not have to remove the peel.
72. To make the drying process quicker, you must reduce the size of the roots. You must chop or shred them.
73. By chopping the roots, you increase the surface area that is exposed to the air. This makes the drying faster.
74. You can cut the roots in whatever shape you like:
- They can be in slices.
- They can be in long strips.
- They can be in big chunks.
75. For quick drying, the thickness must not be more than 5 cm. For the best drying, chips should be about 2 cm in thickness.
76. Cutting the roots also releases the cyanide and helps to reduce cyanide levels.
77. When you are cutting a lot of roots, you must work in an open area with good ventilation.
Area with good ventilation
78. Never cut the roots in a closed room. The cyanide that is released can accumulate in the room and make you sick.
79. You can cut the roots by hand or using a simple shredder. When you have small amounts of roots to process you can handle the work manually using knives.
80. Ideally you should harvest the roots early in the morning, chip them as quickly as possible and start drying by mid- morning.
81. Using a shredder or chopper to cut the roots can save you a lot of labour and time. The shredder can be hand- operated or motor- operated.
hand- operated or motor- operated
82. Making a shredder does not cost much. Your local blacksmith can make you a simple machine.
The machine will basically have:
- rotating knife blades mounted on a wooden frame;
- a hopper into which the roots are fed.
83. If several people in your area are interested, you can join together in a cooperative to get a shredder and other facilities and you can all use them. Such cooperatives have been very successful in Brazil and Colombia.
84. Sun-drying is the method farmers everywhere use to dry cassava chips.
Drying cassava chips
85. You can practice sun- drying during the dry season only; when there is no rain.
86. You must dry the chips as quickly as possible.
87. If a long time is taken to dry the chips, moulds may grow. The quality of the chips will not be good.
88. You can dry the chips in several ways:
- on the floor;
- in trays;
- on mats.
89. Many farmers dry chips on the floor. For a drying floor, you can use any area that is convenient to you, such as:
- rock surfaces;
- roof tops;
- front yards;
- concrete floors.
Dry the chips on rocks
90. If there are rock surfaces around your farm, you can dry the chips on rocks. Rocks become very hot during the day and the chips will dry very quickly.
91. A concrete floor is very effective. It is used in many countries. A floor becomes very hot with the sun's radiation and the chips dry quickly.
92. In some areas, a concrete surface painted with black paint is used. This makes the surface absorb more heat and it becomes much hotter.
93. You can make the drying quicker by placing the chips in trays raised above the ground.
94. You can make trays easily from a wooden frame and the wire mesh that you use in chicken houses.
95. This is a very efficient method of drying, because the chips get heat in three ways:
- direct heat from the sun;
- heat reflected from the ground;
- heat brought by air circulation.
How to spread the chips
96. The chips must be spread in a single uniform layer. This will make them dry more quickly.
97. If you are drying on a floor, you must not spread more than 12 kg of chips over an area of 1 m².
98. If you use more than this amount, drying will be slower. It will take a long time to dry the chips.
99. If you are using trays, you can spread up to 30 kg of chips over 1 m².
100. When the chips are drying, you must turn them from time to time to get a uniform drying.
Get a uniform drying
101. At first, you must turn the chips every one to two hours. After that, you can turn them periodically as you feel it necessary until they are fully dried.
How long should the drying take?
102. Fresh cassava chips are more than 65 percent water. You must dry them until the water content becomes less than 14 percent. Only then can you store them for a long time.
103. You must try to dry the chips as quickly as possible, otherwise moulds may grow. Chips with moulds have no feed value and have to be thrown away.
104. You know well that the drying time depends mainly on the weather that you have while the chips are drying.
105. In sunny, dry weather, you can completely dry the chips in one to three days, depending on the thickness of the chips.
106. If the slices are thin, they will dry faster. In sunny, dry weather, thin slices will dry in less than a day and a half.
Thick slices may take up to three days to dry.
Testing of dried chips
107. You must test the chips to see whether they have dried properly.
108. They can be tested in a simple way. You take the chips in your hand and crush. If they are well dried, they will break easily and will not crumble into pieces.
Crash the chips in hand
109. If the chips are well dried, you can write with them as if they were chalks. This is another test that you can use.
Rains - a problem during drying
110. Rain is the biggest problem during drying. If it rains while the chips are being dried, you must collect the chips and pile them under a roof.
It is bad for chips to get wet
111. It is bad for chips to get wet during drying. Wetting the chips while they are drying will:
- Iead to mould growth;
- increase spoilage.
112. If you expect wet weather, you can take precautions to prevent mould from forming. You can apply a salt solution to the fresh chips before drying.
113. The salt solution can be prepared by dissolving a handful of common salt in a litre of water.
Dissolving a handful of common salt in a litre of water
Proper drying is essential
114. Proper drying is essential if you want to produce chips that can be kept for a long time.
115. From 100 kg of fresh roots, you get about 40 kg of dried chips. So when you dry, you also reduce the bulk of roots and storage becomes easier.
100 kg fresh roots 40 kg dried chips
116. If a product is not properly dried and still contains moisture, it can easily be spoiled by moulds and insects.
117. Well dried cassava chips can be stored for 6 to 12 months.
How should you store the chips?
118. If you want to keep the chips for a long time, you must not store them in open containers.
119. You must store them in closed containers. Otherwise they will be attacked by insects.
120. Insect attack can be a big problem in the long- term storage of dried chips.
121. If bags are used, they must be lined with polyethelene sheets and be tightly closed. Then insects cannot get in.
122. Bags and gunny sacks must be stored on wooden pallets. This will increase the flow of air and also prevent direct contact with the floor.
123. You can use containers made of wood or metal to store the cassava chips. Containers can be made effective by lining them with polyethelene sheets.
124. If it has rained during the drying process or if it took a long time to dry the chips, there is a strong chance that mould will grow and insects attack. You can protect the chips from this by sprinkling them with a salt solution while drying and then storing them carefully.
125. There is another way by which the storage life of the chips can be increased. Immerse the fresh chips in boiling water for ten minutes and then dry them in the usual way. These chips will have a long storage life.
126. Freshly harvested cereals carry insects inside the grain, whereas freshly dried cassava chips have no insects within them.
The insects will come from the storage environment.
127. The storage area must be kept clean and well ventilated. In a good storage environment, you can keep insects out and store the dried chips for a long time.
The storage area
128. Cassava chips occupy considerable space. By milling the chips or pounding them in a mortar, you can reduce the volume.
129. The flour that you prepare by grinding the dried chips is called cassava meal.
130. Cassava meal keeps well in storage. It is not affected by insects as the dried chips are.
131. Cassava meal must be stored in airtight containers because it will absorb water from outside, become moist and can get spoiled.
132. In Thailand, Malaysia and Indonesia, cassava is processed and exported to Europe for use as an animal feed. In Colombia and Brazil, more and more farmers are processing cassava and selling it as dried chips.
133. In these countries, part of the cassava is marketed as dried chips. The balance is marketed as pellets.
134. Pellets are made by pressing the meal into a cylindrical shape. Pellets are made in different sizes, but are usually about 2 to 3 cm long and 0.6 cm in diameter.
135. To make pellets, you need a special machine. Pelleting machines are expensive
136. Pellets have several advantages over cassava meal:
- They are less bulky.
- They are not dusty.
- They can be handled easily.
- They get a high price.
137. Once you are experienced in making cassava chips, you may be interested in making pellets and selling them for more money.