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DEWATERING PARAMETERS FOR ANY [CROP] GIVING MASH

DEWATERING PARAMETERS FOR ANY [CROP] GIVING MASH

DEWATERING PARAMETERS FOR ANY [CROP] GIVING MASH

(OP)
I am currently investigating  dewatering parameters of cassava mash, a very popular food crop in Africa. I  would like to know methods suitable  for this investigation (PRESSURE was identified as very important factor in the investigation). Kolawole Oladele Peter [MNIAE]

RE: DEWATERING PARAMETERS FOR ANY [CROP] GIVING MASH

Would a centrifugal dryer be suitable for your application?  

RE: DEWATERING PARAMETERS FOR ANY [CROP] GIVING MASH

The least expensive dewatering methods use gravity.  This also allows decanting from the top or bottom of the vessel. Allowing the mash to settle for a time may allow some water to be removed.  A second method could use a slurry spread on a fine screen and possibly a vacuum below to speed water movement.
Depending on the volume of mash and the energy resources available, have you considered solar?

RE: DEWATERING PARAMETERS FOR ANY [CROP] GIVING MASH

(OP)
Thank you,
Cassava is the most perishable of roots and tubers and can deteriorate within two or three days after harvesting.  Additionally, the roots need to have the cyanogenic glycosides reduced to a level, which is acceptable and safe for consumption.  For these reasons, cassava is usually sold as processed product hence the end product is affected by methods use. My focus is on GARI production, were sacks of cassava mash must be dewatered in a shortest  time possible. This it the main reason for documenting the parameters involve for Engineers use. Kolawole, O. Peter MNIAE [ work for iita ibadan]

RE: DEWATERING PARAMETERS FOR ANY [CROP] GIVING MASH

From a description of the process for making gari, it appears that the first dewatering takes place after the root is chopped into 3-5 mm thick pieces.  This size and process is similar to the making of cider (apple juice).  
The apples are gathered and pulped and then the juice extracted by several processes, the oldest of which is mechanical pressure.
Perhaps a search of cider making equipment would help.  
The description I read mentioned the use of pressure in the later stages of gari production.  Perhaps the same equipment could do both stages thereby increasing it's usefulness.
Interesting project.

RE: DEWATERING PARAMETERS FOR ANY [CROP] GIVING MASH

(OP)
Cassava De –watering methods
Dewatering is done in Nigeria using boulders, logs, sticks, parallel board, tree stumps string, chain, screw and hydraulic methods.  Aribisala (1992) had the list of these methods,your information is very useful but can you let me know if this information on cider is available on web or get it sent to me. I need to Identify these parameters

RE: DEWATERING PARAMETERS FOR ANY [CROP] GIVING MASH

In order to clarify the question you ask, I need to ask additional questions.
First, at what level of technology do you wish to operate?  If you wish to process the mash in batches, the yield will be different than if you wish to run an automated continuous flow process.  If working with a manual or hydraulic batch press in apples, the typical yield will be about 11.5 kilos of liquid from 24.5 kilos of fresh fruit.  This is at about 800-900 kpa.
Second, what is the water content of the root at the start?
Third, what type of crushing/chopping equipment is available?  A fine mash, slightly larger than cornmeal, gives the best results with cider but also has a problem with too much solid matter in the juice.  Will this be a problem for you?
From the description of the gari process I read, it sounds as though a chopped mash able to pass through a screen with 1-1.5 cm openings might be a good starting point.
Also, I would make another suggestion.  Find the area that makes the best gari, look at how they process it, and then, attempt to duplicate that mechanically.  You will be starting with a known and accepted product which will be more readily accepted by your consumers.
There are several books available on cider making in small quantities.  Perhaps one of these would give more definitive answers.  Space here seems awfully limited.

RE: DEWATERING PARAMETERS FOR ANY [CROP] GIVING MASH

(OP)
pkolawole@hotmail.com is my address,
At the lowest level of technology available, to be developed as time goes on.
 Onwueme and Sinha (1991) reported  the composition of cassava tuber as: 62% water, 35% carbohydrate 1-2% protein, 0.3% of fat, 1-2% fibre, and 1%mineral matter.
 Gari is prepared by peeling cassava tuber and grating it into mash, fermenting and dewatering the mash.  The  mash is then partially gelatinised, dried to moisture content of about 12% (d.b).  In the traditional operation, fermentation and pressing (de-watering) are done in one operation. The grated mash is packed inside baskets, Jute bags or perforated plastic sacks and left to ferment for 1-4 days.  The duration of the operation affects the colour, taste and texture of the Gari.

RE: DEWATERING PARAMETERS FOR ANY [CROP] GIVING MASH

(OP)
Would a centrifugal dryer be suitable for your application? ornerynorsk (Industrial). I am sorry reacting to your views late. Centrifugation increases the mass forces on particles and thus extends sedimentation to finer particle sizes .In case of cassava for the production of GARI may not be suitable as the end product might be affected.
 Centrifuges may be used to dewater (U.S.EPA, 1987).  The percent of output can be varied by changing operational parameters.
 Like all dewatering equipment, centrifuges require a capital investment, and labour to operate.  A comparism study of centrifugation and direct pressure as means of de-watering was made by Straut, and Bruhn in 1978 in determining the dewatering characteristics of alfalfa protein concentrate.  A set of tabular inserts was constructed to fit inside the tubes of a laboratory sedimentation centrifuge.  The tubes has screened bottom and allow the moisture to move radically outwards as would occur in a filtration centrifuge.  Freshly coagulated protein was placed in the filtration tubes at a give depth dewatering  by running the centrifuge for a given length of time was done and moisture content tested.

The result indicated that comparable dewatering can be obtained by use of filtration centrifuge.  Increased acceleration or increased holding time did not give large decreases in final moisture content of the sample.
Separation of solids from liquid in Agricultural practices cost great deal of money,What I was looking for is a very cheap method that can be of use to the poor farmers in Africa

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