The Bioscientist (Jan 2018)
Shelf Life Extension In Burukutu, A Nigerian Alcoholic Beverage Using Antimicrobiologically Active Spices
Abstract
Common food preservation methods such as pasteurization or the use chemical preservatives render burukutu, a Nigerian alcoholic beverage unacceptable because they further gelatinize starch or eliminate the beer’s characteristic effervescence through the killing of active yeasts. Spices are known to be selective in their inhibition of different types of microorganisms. The objective of this study was to select spices, which would inhibit the growth of spoilage organisms but allow the growth of active yeasts such that shelf life of burukutu is extended with retention of beer’s characteristic effervescence. Lactic acid bacteria, acetic acid bacteria, yeasts and molds isolated during the fermentation/spoilage of burukutu were screened for susceptibility to ethanolic extracts of the rhizome of Zingiber officinale, leaves of Cymbopogon citratus, seeds of Aframomum melegueta, leaves of Gongronema latifolium and the tree bark of Sacoglottis gabonensisin using plate assays .Burukutu brewed with aqueous extracts of these spices were also tested for acceptability using the 9-point Hedonic scale and a panel of regular burukutu drinkers. No spice extracts showed absolute selective antimicrobial activity against any specific organisms. However, in the plate assays, extracts of Zingiber officinale showed a stronger inhibitory activity on the growth of molds and the acetic acid bacteria than it demonstrated against yeasts. Burukutu brewed with this spice showed a reduced rate of growth of all organisms particularly, the molds and the acetic acid bacteria and hence prolonged the shelf life for at least three days. Burukutu flavored with this spice was also acceptable; mean score by panelists was 7.2963a0.49 compared with 7.7037a0.39 for the control.
