The kinetics of sugar degradation were measured by Brix
changes of must during fermentation (Fig. 2A). In grams of solute/
100 g of solution (g/g), Brix is the % of total soluble solids in solution
(Son, Hong, Park, Yu, & Lee, 2009). It is the most common
unit for sugar content in the wine industry because sugars are the
predominant soluble solids in fruits. The wine without nutrients
was considered sluggish fermentation as sugar consumption was
still present at the end of fermentation (38 days). All nutrients
showed positive effects on sluggish fermentation, but to varying
degrees. 6% banana and DAP additions had strong effects on
improving the sluggish fermentation, followed by 4% banana, 2%
banana, and yeast extract addition, respectively. As the fermentation
progressed, the differences in Brix between the tested samples
and the control increased and peaked at 18e22 days of
fermentation (Fig. 2B). The gap in sugar contents between the
musts with and without nutrients decreased to 1 Brix at the end of
fermentation (38 days), as the remaining sugars were consumed by
yeast. Blateyron and Sablayrolles (2001) determined that ‘stuck’
and ‘sluggish’ fermentations occur when the fermentation rate
dramatically decreases at the end of fermentation while ‘slow’
fermentations are characterized by a low fermentation rate
throughout the process. According to this standard, blueberry wine
fermentation could be defined as ‘slow’ fermentation beca