| dc.description.abstract | Sugarcane juice is known to have an abundant nutritional composition, including a
fairly rich content of electrolytes, vitamins, minerals and remarkably high percentage
of sugars. Even though Vietnam is one of the big sugarcane growers in Asia, there is
only a limited understanding of yeast species associated with sugarcane plants in
Vietnam and alcohol beverages made from sugarcane juice has not received much
attention in the country. As, the qualities of fermented beverages have long been
reported to depend on the activities of the yeast(s) involved. Thus, the objective of
the current research was to isolate yeast strains from sugarcane plants and evaluate
their ethanol producing capacities using sugarcane as the sole substrate.
Two sugarcane varieties, including purple and green skinned types, were either peeled
or unpeeled and crushed for juice extraction that was used right away for the
microbial isolation (direct isolation) or the juice was naturally fermented for one week
(enriched culture isolation). Five different yeast strains were isolated and based on
their morphological characteristics they were putatively identified as Saccharomyces
cerevisiae (D), Candida albicans, and Hanseniaspora vineae, Candida tropicalis and
Debaryomyces hansenii. S. cerevisiae, C. albicans, and H. vineae were found in green and
purple sugarcane, the yeast strain C. tropicalis was found in green sugarcane and D. hansenii
was found in purple sugarcane.
The ability to utilize sugarcane juice of the isolated yeasts was record: Before fermentation,
the sugarcane juice had the total TSS (18.51± 0.03 oBrix), and the reducing sugar
(29.41± 0.01 g.L-1) and these were significantly reduced after 7 days of fermentation in all the
cultures. This suggested that the yeasts could utilize sugarcane juice well. However, only
yeast strains like S. cerevisiae, C. tropicalis, and D. hansenii were able to ferment
sugars into ethanol. In addition, H. vineae and C. albicans hardly produce ethanol. The
most potential strain for alcohol production was S. cerevisiae, which produced 12.63
± 1.11c g.L-1. C. tropicalis and D. hansenii also could produce ethanol production that
produced 7.41 ± 1.85b g.L-1 and 7.20 ± 1.15b g.L-1. Therefore, S.cerevisiae(D) is most suitable
for ethanol production with the highest fermentation efficiency 88.23 ± 7.97c % and ethanol
productivity 0.08 ± 0.007c g.L-1.h-1. | en_US |
