CYPERUS ESCULENTUS: PHYSICAL PROPERTIES OF TUBERS AND MICROBIOLOGICAL CHANGES DURING NATURAL FERMENTATION IN NIGERIA

Abstract

This work reports the comparison in the physical properties of tiger nut tubers (Cyperus esculentus), a crop extensively cultivated in Northern Nigeria as well as in the biochemical changes which occur during the spontaneous fermentation of the soaked tubers in water for tiger nut beverage production. Both the brown and yellow tuber varieties of C. esculentus were used in this study. For each variety, the length and width of 100 randomly selected tubers alongside the weight of 1000 tubers were determined. Furthermore, 10g of each variety was steeped in sterile distilled water for periods of time that ranged from 0-96 hours in order to highlight the bacterial and fungal diversities occuring among the tubers. Results of the physical properties revealed that the yellow variety tubers were highly significantly longer in length, bigger in size, have higher length/width ratio, and heavier in weight than the brown variety tubers. When steeped in water, the mean range count of log 2.763 – 10.20 CFU/g for lactic acid bacteria  and log 2.073 – 7.73 for yeast/mold count in the brown tubers were significantly higher than the range of log 2.51 -6.14 and 1.56 – 8.17 obtained for the same parameters, respectively, in the yellow tubers. The dominant microorganisms during the steeping process, regardless of the variety, included Bacillus species, Gram-negative group Enterobacteriaceae, as well as yeasts, moulds, and acetic acid bacteria. These array of microorganisms are for assessment and proper selection of desirable strains, as potential starter cultures, towards tiger nut beverage production.