ITDG 
Interdev Agroalimentaire  

Small-scale sugar production from sugar cane

	Type de fiche	Techniques/Technologies
	Mise en œuvre	ITDG(Royaume Uni)
	
	Zone géographique	Global; 
	Mots clés	SUCRE; PRODUCTION A PETITE ECHELLE; CANNE A SUCRE

	Echelle d’action	Groupe
	Public(s) cible(s)	Small- and medium-scale food processors

Contexte
Sugar is formed from the extracted juice of sugar cane.  The sugar cane has to be crushed to extract the juice.  The juice is collected from the stems, filtered and then boiled to drive off the excess water.  The dried cane residue, which is known as bagasse, is often used as fuel for the boiling process. The remaining liquid is allowed to set into a solid mass, which is known as gur, jaggery, chancaca or panela, depending on the country of production. The sugar is referred to as gur in this fiche.

The product is a solid, brown/black, crystalline sugar with a sweet taste. It is sold in moulded shapes, particularly in rural areas.  It is eaten as a sweet, used in traditional confectionery products or instead of refined cane sugar.  The sugar has a shelf life of one year or more.

Boiling the juice inactivates enzymes and destroys micro-organisms and also evaporates water to give the desired flavour and texture. The high solids content prevents re-contamination by micro-organisms.
Similar products are made in Asia from palm saps.

Problématique / Objectifs
  The yield of gur from sugar cane depends mostly on the quality of the cane and on the efficiency of the extraction of juice. High quality cane has a good juice content (eg 50kg juice per 100kg cane) with high sugar levels (over 20% sugar in the juice).  Poor quality cane, or cane that has been harvested too early may have a similar juice content, but the levels of sugar will be lower (about 17%).
  The cane must be crushed within 24 hours of harvest. After this time the sugar begins to invert into different sugars that will not set solid.
  Crushing efficiency is the most important factor in good sugar yields. Every possible amount of juice needs to be squeezed from the cane.
  Cleanliness is important to the whole process. Once the juice has been heated, impurities will speed the inversion of sugar and lead to reduced yields. All boiling pans and tools need to be thoroughly cleaned between uses.
  Many produces add Hydros (sodium hydrogen sulphate) at the final stages of boiling. This releases sulphur dioxide in to the juice and lightens the colour of the final product.  However, the final product often retains a high sulphur content.
  The end point of boiling is judged from experience - from the sight and sound of the boiling juice. Small samples of juice are removed for testing to see if they set when cooled.  Alternatively, the sugar content of the juice can be measured using a refractometer if available. The sugar content should measure 90-95  Brix.

Description/Mise en oeuvre
Sugar is produced according to the following basic process:

  Crushing
  Juice treatment
  Boiling
  Cooling.

Crushing
Sugar cane should be crushed within 24 hours of being cut. Simple crushers are available, powered either by animal or diesel power. It is important to squeeze out all the available juice.

Juice treatment
The juice is filtered through a fine cloth before boiling to remove any solids such as dirt or particles of cane.
Some small-scale processors add clarifying agents to the juice to help settle out the impurities.  Wood ash is a common additive. Large-scale processors add lime to the juice to coagulate the impurities, then neutralise the juice with sulphur dioxide.  This is rarely carried out at the small-scale.

Boiling
The juice is boiled in large pans over open fires or simple furnaces. The essential requirement is for clean pans and tools. During boiling sediment settles to the bottom of the pan and needs to be scooped out.  Scum also rises to the top and has to be skimmed off. Both these waste materials can be fed to cattle. The boiling pans are usually made of galvanised mild steel sheets.

Boiling is carried out until the majority of water has been driven off.  For example, from 100kg juice, to a final yield of 20kg gur. This is judged by experience.

Cooling
After boiling, the pan is removed from the heat and the juice stirred rapidly to incorporate air. This helps to achieve a uniform rate of crystallisation of the sugar.  The cooling juice is then poured into pots or moulds and left to set.

Résultats/Eléments chiffrés
  Most small-scale producers use a simple crusher made of 3 metal rollers. A crusher driven by a single ox will only process about 50kg cane per hour.  A 5HP diesel engine could increase this to about 300kg per hour.

In addition to an efficient cane crusher, the other tools required are very simple;
  Filtration before boiling is carried out through a fine woven cloth.
  Scum is removed from the top of the juice using a perforated scoop on a long handle.
  Sediment is removed from the bottom of the pan by scraping a stretched cloth along the bottom of the pan.
  A simple rake is used for stirring the cooling juice.

Enseignements
  The efficiency with which juice can be extracted from the cane is limited by the technology used. The simple three roller crushers used by most artisans will never extract more than 50kg of juice from each 100kg cane.
  Yields are improved by careful control of the boiling process. Boiling should be completed as rapidly as possible and the conditions kept as clean as possible.

Auteur : Sue Azam Ali
Saisie le : 06/12/2001
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