The methanol,ethanol and fusel oil contents of some Zambian alcoholic drinks

Abstract

There is considerable evidence that certain Zambian home-produced beers and spirits contain toxic contaminants. Apart from known additives such as methylated spirits and plant juices, high levels of iron, copper and zinc have been recorded (Reilly and MCGlashan 1969; Reilly 1973 a and b). These metals normally result from the use of galvanized iron containers during fermentation. The toxic effect of high iron levels in beer has been noted by Lowenthal et al (1967). A potent carcinogen of the nitrosamine group has also been detected in certain Zambian drinks (MCGlashan, Walters and MCLean 1968). As a further step in such investigations of locally produced drinks, we looked at levels of methanol and fusel oils, as well as ethanol, in both commencially available and home-produced samples of traditional Zambian beers and spirits. Methanol, or wood spirit, is a common contaminant of alcoholic drinks. It is a highly toxic substance and can, depending on the quantity consumed, lead to blindness, insanity and even death. Methanol is not produced by yeasts fermentation but results from the break-down of` pectin in plant material by the enzyme pectinase. Fusel oil is the collective name given to a mixture of such higher alcohols as isoamyl, active amyl and isobutyl alcohol. It is produced by the action of enzymes on amino acids present in the fermentation medium. The oils are highly toxic and have been shown to cause cancer in experimental Animals (Gibel, Wildner and Lohs 1968, Purchase 1969). They also account for the aroma and taste of drinks and are responsible for the severe headache and thirst associated with a hangover.