Under aerated culture, the maximum number of yeast population by both yeast showed an increase compare to nonaerated
culture. The maximum number of yeast population by New Aule Alcohol Yeast And New Aule Baker’s
Yeast under aerated culture were not significantly different throughout fermentation, as respectively the result are
8.62 log cfu/ml and 8.50 log cfu/ml.
Fig. 1 showed that the increase on population number of yeast strains until 36 hours of incubation time was
hypothesized because of the availability of sugars from molasses as the source of energy is high enough for the
growth of yeast. The number of yeast population from each strains during the 36 hours until 48 hours of incubation
time was tend to be stable. It was hypothesized that in those fermentation time, each yeast strains was going through
the stationary phase (in which the phase of yeast growth is slowly decreasing/become limited and the cells stop
dividing). The two commercial yeasts were hypothesized going through in an early death phase because of the
decreasing number in yeast population during the 48 hours until 72 hours of incubation time. The decreasing of
yeast population number was hypothesized because of the sugars content decreased so that it was not possible for
the yeast to grow any further.
Based on t-test, the maximum numbers of yeast population under non-aerated culture compare to aerated culture
were shown to be significantly different. It means that aeration could affect the number of yeast population during
fermentation. Aeration in the culture media gave oxygen supply to yeast because in the earlier stage of incubation
time, yeast were undergone aerobic fermentation to optimize its growth, so the result shown the increasement in
number of yeast population. Khongsay et al. (2012), reported that aeration in the earlier stage of fermentation is
importatnt for yeast due to its needed to synthesize cell membran (sterols and unsaturated fatty acids), which are
essential to assure cell membrane integrity as well as to vent out CO2 that could inhibit yeast growth. Meanwhile,
Alfenore et al. (2004), stated that aeration 0.2 vvm in culture under fed-batch fermentation could increase cell
viability up to 23%. Hence, the maximum numbers of yeast population under aerated culture were tend to be higher
than yeast under non-aerated culture because the oxygen availability in media were well used for yeast growth.