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Cassava Peeling

"Hand peeling is still the best way"

Peeling is an important operation in cassava processing. A cassava peeler should completely remove the peel without removing the useful part of the root. In addition, the peeled surface should be clean and undamaged.

When processing cassava to starch, it is sufficient to just wash the root which removes the dark outer layer that covers the root. However, when processing cassava to any other form it is necessary to remove the dark outer layer and the white corky layer underneath. This requires peeling.

1. Types of cassava peelers

Different approaches to cassava peeling are compared below.

Hand peeling

Hand peeling with knifes is currently the only method that can remove all the peel with minimum root losses. Currently no peeling machine can achieve the same level of root losses and peel retention obtained by hand peeling.

The general recommendation is to invest on improving the hand peeling rather than investing on peeling machines. Proper working environment, tools and conditions for the peeling team can assures minimal root losses and peel retention plus maximum throughput.

Summary

  • Minimum root losses
  • Minimum peel retention
  • Change throughput easily by changing peeling personel
  • Tedious
  • Labour intensive

Abrasion peeler

The main parts of this equipment are a rotating drum and a water sprayer. The drum with abrasive surface rotates and removes peel from the roots while water is sprayed to wash it. The drum is rotated by belts and pulleys connected to an electric motor.

Cassava roots have irregular shapes meaning the abrasive surfaces of the drums cannot reach all the peel, resulting in significant losses of the useful flesh or peel being retained. Problems can also occur when peeling roots of different sizes: large roots remain mostly unpeeled while small ones might be completely grated and lost.

Best results are achieved if the roots are sorted by size, and regular shaped roots are chosen.

Summary

  • Reduced labour required for peeling
  • High root losses
  • High peel retention

Cylindrical knife peeler

In general, this kind of peeler consists of a cylindrical knife assembly and a solid cylinder with a rough surface, both mounted parallel. The equipment is usually driven by an electric motor. In some designs the cylinders rotate at opposite direction while in other designs both cylinders rotate at the same direction but at different speeds.

Cassava roots have irregular shapes meaning the abrasive surfaces of the drums cannot reach all the peel, resulting in significant losses of the useful flesh or peel being retained. Problems can also occur when peeling roots of different sizes: large roots remain mostly unpeeled while small ones might be completely grated and lost.

Best results are achieved if the roots are sorted by size, and regular shaped roots are chosen.

Summary

  • Continuous operation
  • Can have high throughput
  • High root losses
  • High peel retention

2. How to measure performance

Root losses is the percentage of the useful part that was removed with the peel. The lower the root losses the better.

Peel retention is the percentage of the peel that remains on the root after passing through the machine. The lower the peel retention, the better.

Throughput is the amount of material passing through the peeling machine When examining throughput it is important to verify if the peeler operates in batch or continuous mode, and preference should be given to continuous one.

Peeling efficiency is sometimes given but can be misleading as it can be calculated in different ways. If a seller quotes the peeling efficiency of their machine, ask them to provide root losses, peel retention and throughput instead.

3. Quality and safety

  • All parts that come in direct contact with the roots should be constructed with food-grade stainless steel.
  • Do not purchase equipment where food contact materials have been painted.
  • All components of the belt drive should be enclosed under a safety guard. Do not purchase an equipment that has exposed belts.

4. Before buying a peeling machine answer these questions

  • Are there strong reasons to invest in a cassava peeling machine instead of enhancing the peeling team working conditions?
  • Using the root losses provided by the manufacturer, have you calculated how many kilograms of cassava you will be losing per day, by using a peeling machine? Have you considered the cost of those losses?
  • Considering the peel retention, provided by the manufacturer, have you costed the decline on product quality if you decide to process the root without removing the remaining peels?
  • Have you considered the cost of labour that will be required to 1) sort the roots by size to reduce root losses and/or 2) remove the remaining peel after mechanical peeling?
  • Are all parts that come in contact with food made out of food-grade stainless steel?
  • Are all belt drive components enclosed by a safety guard?

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