THE ROLE OF MICROBIAL GUMS IN THE COLOR AND CONSISTENCY OF PALM WINE

Viscosity and soluble color changes in palm wine during fermentation were found to show an early increase followed by a gradual decline. Addition of absolute alcohol to palm wine precipitated gums that were absent in the palm sap, indicating production during fermentation. Precipitation of the gum was accompanied by loss in coloration and a significant reduction in viscosity. These properties were regained on reintroduction of the gum showing that the gums were responsible for the properties. Yeasts and bacteria isolated from palm wine were employed in pure culture fermentations of sterile palm sap to determine the origin of the gums. The results showed that the gums were produced mainly by leuconostocs, while two other bacteria not fully identified and a homofermenting Lactobacillus spp. also produced some. Analysis showed the Lactobateriaceae gums to be all glucans, while the gums of the other bacteria were fructans. Palm wine was found to contain both types of gum (80% glucans, 20% fructans), showing that many bacteria produce gums in palm wine concomitantly.