ITDG 
Interdev Agroalimentaire  

Small-scale production of banana beer

	Type de fiche	Techniques/Technologies
	Mise en œuvre	ITDG(Royaume Uni)
	
	Zone géographique	Global; 
	Mots clés	BIERE; BANANE; BOISSON; FERMENTATION; SORGHO

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

Contexte
Banana beer is a traditional product made in African countries.  It is produced from bananas mixed with a cereal flour (usually sorghum flour).  The beer is a hazy orange colour with a sweet taste. It has a shelf life of several days under correct storage conditions.

There are many local variations in the method used to produce banana beer, depending upon what raw materials are available, although the principles are the same. In Kenya, Urwaga beer is made from bananas mixed with either sorghum or millet.  Lubisi beer is made from bananas of the Jamaican variety mixed with sorghum flour.

Similar beers are made in most countries using saps, juices and extracts from cereal grains.

Problématique / Objectifs
Preservation is achieved by the relatively high levels of alcohol which inhibit the growth of many spoilage micro-organisms.

The process involves the preparation of banana juice, mixing with sorghum (or cereal) flour and fermentation by yeasts to produce the alcohol.  There is no boiling stage in traditional processing, which contributes to the relatively short shelf life.  Improved processing could introduce a boiling stage and pasteurisation of the product, which would improve the quality and extend the shelf life of the product.  However, these two processes will also affect the taste of the final product.

Because the raw materials are not sterilised by boiling the wort (the wort is the mixture of substrate that is fermented to produce alcohol), this is an excellent substrate for microbial growth.  Obviously, certain micro-organisms (notably yeast) are required for the fermentation to take place, but it is essential to prevent contamination by other microbes that will spoil the beer and could potentially cause food poisoning.

It is essential that proper hygienic procedures are followed and that all equipment is thoroughly sterilised to prevent the competing bacteria producing acid instead of alcohol.  This can be done by cleaning with boiling water or with chlorine solution. Care is necessary to wash the equipment free of chlorine residue as this will prevent the activity of yeast. Strict personal hygiene is also essential.

Description/Mise en oeuvre
A detailed production flow sheet is available (ref link).

The basic process is as follows:
  selection of raw material
  extraction of banana juice
  mixture with cereal flour
  fermentation
  filtration
  packaging

Selection of raw material
Bananas should be harvested when they are fully ripe as they contain more sugars and have a better flavour. Unripe bananas do not contain enough sugar. Over-ripe bananas should not be used as they may impart off-flavours to the final product.  The bananas are peeled and any bad bits discarded.  If the peels do not come away easily, the bananas are under-ripe.

Extraction of banana juice
The juice is extracted from the bananas by squeezing and kneading the fruit in grass. This produces a clear juice, while the fibrous residue remains in the grass. The banana juice is mixed with clean drinking water in the ratio of 1 water to 3 banana juice. This reduces the concentration of the banana liquid to a total soluble solids level that is suitable for the yeast to act on.

Add cereal flour
The banana juice is mixed with sorghum flour in the ratio of 1 sorghum flour to 12 banana juice.  The mixture is stirred well.  Sorghum flour is added to improve the flavour and colour of the beer.

Fermentation
The mixture is left to ferment for 18-24 hours at ambient temperature in a plastic container, covered by polythene bags or flat wood that is held down by a heavy stone.  The cover ensures that the fermenting beer is not contaminated by dust and other foreign bodies.  It also helps to maintain an anaerobic environment.  An improved method is to use a fermentation vessel that has a fermentation lock.

Filtration
After 18-24 hours fermentation (or when the liquid is no longer actively fermenting), the liquid is filtered through a cotton cloth bag.  It is firmly squeezed either by hand or using a small press. The residue is discarded or may be used for animal feed.

Packaging
The beer is packaged in 1litre plastic bottles or similar with cork stoppers.  It is stored away from direct sunlight in a cool place.  The shelf life of the product is not more that a few days, therefore packaging is merely to store the product until it is drunk, rather than for display or sale purposes.  If plastic bottles are not available, cleaned glass ones can also be used. Traditionally, gourds are used for storage.

Résultats/Eléments chiffrés
The following equipment is required:
Knives
Filter bags
Fermentation vessel

Enseignements
The main quality control points are to extract a high yield of banana juice while avoiding excessive browning and contamination by spoilage micro-organisms.  Also, to carry out filtering to ensure a clear beer.

The main quality factors are colour, flavour and clarity of the beer. The colour and flavour are determined mostly by the preparation of the banana/sorghum mixture. The clarity of the final product is determined by the success of filtration.

Auteur : Sue Azam Ali
Saisie le : 05/12/2001
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