FERMENTED PLANT SAPS
Virtually any sugary plant sap can be processed into an alcoholic beverage. The process is well
known being essentially an alcoholic fermentation of sugars to yield alcohol and carbon dioxide.
Many alcoholic drinks are made from the juices of plants including coconut palm, oil palm, wild
date palm, nipa palm, raphia palm and kithul palm.
Palm ‘wine’ is an important alcoholic beverage in West Africa where it is consumed by more than
10 million people. Palm wine can be consumed in a variety of flavours varying from sweet
unfermented to sour fermented and vinegary alcoholic drinks. There are many variations and
names including emu and ogogoro in Nigeria and nsafufuo in Ghana. It is produced from sugary
palm saps. The most frequently tapped palms are raphia palms (Raphia hookeri or R. vinifera)
and the oil palm (Elaeis guineense). Palm wine has been found to be nutritious.
Raw material preparation
Sap is collected by tapping the palm. This is achieved by making an incision between the
kernels and a gourd is tied around to collect the sap which is collected a day or two later. The
fresh palm juice is a sweet, clear, colourless juice containing 10-12 percent sugar and is neutral.
The quality of the final wines is determined mostly by the conditions used in the collection of the
sap. Often the collecting gourd is not washed between collections and residual yeasts in the
gourd quickly begin the fermentation.
The sap is not heated and the wine is an excellent substrate for microbial growth. It is therefore
essential that proper hygienic collection procedures are followed to prevent contaminating
bacteria from competing with the yeast and producing acid instead of alcohol.
Fermentation starts soon after the sap is collected and within an hour or two becomes reasonably
high in alcohol (up to 4%). If allowed to continue to ferment for more than a day, it starts
turning into vinegar. Some people like a vinegary flavour. The organisms responsible are mainly
S. cerevisiae, and Schizosaccharomyces pombe, and the bacteria Lactobacillus plantarum and L.
mesenteroides. There are reports that the yeasts and bacteria originate from the gourd, palm
tree, and tapping implements. However, the high sugar content of the juice would seem to
selectively favour the growth of yeasts which might originate from the air. This is supported by
the fact that fermentation also takes place in plastic containers. Within 24 hours the initial pH
is reduced from 7.4-6.8 to 5.5 and the alcohol content ranges from 1.5 to 2.1 percent. Within
72 hours the alcohol levels have increased from 4.5 to 5.2 percent and the pH is 4.0. The
organic acids present are lactic acid, acetic acid and tartaric acid.
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