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Cassava Production: Harvest and Post Harvest Activities


Cassava is a highly perishable crop. It starts to deteriorate as early as one to three days after harvest. Harvest cassava at the right time and in the proper way. To prolong its shell-life, store it properly. Harvest cassava at full maturity or 6-7 months after planting. Harvesting too early results in low yield and poor eating quality. On the other hand, leaving the roots too long in the soil expose them to pests. It also ties the land unnecessarily to one crop.
Important points when harvesting cassava. 1. Do not harvest cassava right after a heavy rain or when the soil is too wet. At this time, the roots have high water content which make them difficult to store. Also, wet soil particles would stick easily to the roots especially if the soil is clayey, thus making the roots hard to clean. Harvest cassava during relatively dry weather so that you can easily remove the soil particles from the roots. 2. Harvest only what is needed for food or processed within 2 days. Cassava roots cannot be stored under ambient condition for more than 2 days because they develop vascular streaking which affects the quality of the by-product. 3. Avoid wounding the cassava roots because it causes rapid deterioration of the roots. If the soil is compact, loosen it first. Use a wooden tool because this can cause lesser root damage than metal tools. Pull the plant gently and don't drag the roots. Dragging can cause bruises and cuts to roots, which may lead to early deterioration. 4. In separating the roots from the plant, do not just break it off because this method can also cause root damage. Instead, separate the roots from the stem using a sharp knife or bolo. Cut each as close to the stem as possible Separate & process first the damaged and small roots in order to minimize the growth of molds. Sorting may not be necessary when roots are immediately delivered to the processing plant. 5. After harvesting, don't leave the roots under the sun. Too much heat causes weight loss and early root deterioration. Post-harvest Practices The following are some activities that can be done after cassava harvest:
  • Pre-drying
Sun-dry newly harvested roots for 4 hours or less to easily remove soil particles.
  • Processing of Cassava Chips
Wash the roots with water to remove soil particles and other foreign matter that may contribute to low quality of the end products. Cut the woody portion of the roots using a sharp knife or bolo. Use the sharp knife or bolo to peel the roots intended for the manufacture of starch or flour. Roots for the animal feeds need not be peeled, however. Cut the roots into thin slices not more than 5 mm thick. Chipping can be done through manual or mechanical chopping of fresh roots. The ideal thickness of chips is � inch. Manual chipping can be done by cutting the roots diagonally or crosswise using a sharp knife or bolo. Mechanical chipper can process larger volume of roots in a shorter period of time with lesser cost.
  • Directing Sun Drying:
Lay bamboo or other woven mats on a flat cleared ground fully exposed to sunlight. Spread the chips evenly but not too thickly on the mats.
  • Storing Dried Chips:
When dried chips are not milled right away, store them properly to prevent moisture re-absorption. Place the chips either in pails with cover or sacks with cellophane lining (like thoroughly washed fertilizer sacks), in jute sacks or containers that can be closed.
  • Granulation
Fresh roots can also be chopped into smaller size of about 8-10 mm using a cassava granulator. Granules require shorter period of drying, higher price and are less bulky to transport.
  • Drying
Spread chips or granules evenly not more than 3 inches thick in a clean dry pavement or tarpaulin/plastic net for 2-3 days for sun drying. Dry to 14% moisture content or lower for longer storage. Do not dry chips/granules in sandy areas to avoid contamination. In areas with frequent rains, the use of plastic roof shed with elevated floori ng can serve as drying facilities. This can also be used as the initial (1-2 days) stage before transferring the chips/granules to a mechanical dryer.
  • Storage
There are several methods of storing cassava. Among these are soil storage method and storage of roots in wooden crates. Select suitable storage site, which is well drained, preferably shaded, and slightly sloping. Do not keep cassava in a waterlogged area because roots will decay easily. In the selected area, dig trenches measuring one meter in width and 30-40 cm in depth. The length of the trench varies according to the volume of roots to store. A meter long trench can contain 70-80 kg roots. Dig the trenches in such a way that their length will be running downhill. At the lower end of the trench, make a drainage canal, which should be at least 20 cm wide and 5 cm to 10 cm deeper than the storage trench. Arrange mature, undamaged roots inside the trenches. Cover each layer of roots with soil, preferably riversand or seasand. If these types of soil are not too wet. Absolutely, do not use heavy wet clay to cover the roots because this type of soil could just enhance root deterioration. Pack dried chips/granules in clean laminated sacks or Polypropelene sacks and tie it tightly. Store cassava in dry, shaded and well ventilated area. Use wooden pallet to elevate the sacks from the flooring.
  • Cassava Flour and Starch
Use tubers that are not fibrous, about 10 months old and not later than 16 months old after planting. They should be used within 24 hours after harvesting. Preparation:
  1. Wash, peel and re-wash tuber after peeling.
  2. Slice thinly or shred by means of a papaya shredder.
  3. Soak or wash in enough water to remove part of the starch and should be allowed to settle. Drain the shredded cassava.
  4. Line a "bilao" or basket with sinamay cloth and spread the shredded cassava. Dry until crisp or brittle.
  5. Grind through a cornmeal grinder and pass through a No. 120-mesh sieve. This is the cassava flour. Pack in airtight container, preferably plastic bags and seal.
  6. The water where the cassava was soaked contains the starch (step 3). Decant off the water and completely dry the starch under the sun. Pack in dry containers.
Fresh Root Yield = 60,000 kls./ha (Rayong) Drying Yield= 28,200 kls @ 8.00 /kg dried chips Gross Income = P 225,600.00 Less Expenses = P 68,860 Net = P 156,740 Note: Cassava Contract Growing has a conract price of 11 to 15 pesos per kilo as of Nov 2015

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