Simultaneous Saccharification and Fermentation of Sugar Beet Pulp for Efficient Bioethanol Production
Table 2
Effect of simultaneous saccharification and fermentation conditions on sugar beet pulp-based wort fermentation factors and intake of sugars.
Fermentation trial
Parameters
Pretreatment
Without pretreatment, pulp suspended in water
Pressure-thermal pretreatment
Ultrasound pretreatment
30 min
60 min
50% amplitude, 20 min
100% amplitude, 20 min
Pulp suspended in water
Pulp suspended in 2% w/w sulfuric acid solution
Pulp suspended in water
Pulp suspended in 2% w/w sulfuric acid solution
Pulp suspended in water
Pulp suspended in 2% w/w sulfuric acid solution
Pulp suspended in water
Pulp suspended in 2% w/w sulfuric acid solution
Initial fermentable sugar content as sum of glucose, fructose, galactose, saccharose, and xylose [g/L]
51.75 ± 1.55
55.18 ± 1.65
62.21 ± 1.86
55.45 ± 1.65
62.85 ± 1.90
52.23 ± 1.40
51.43 ± 1.54
51.27 ± 1.54
54.67 ± 1.64
Without enzymatic activation
Ethanol content (g/L)
14.3 ± 0.6
19.9 ± 0.7
22.5 ± 1.1
20.5 ± 0.8
22.7 ± 0.9
15.8 ± 0.4
16.3 ± 0.5
16.2 ± 0.5
17.5 ± 0.7
Fermentation efficiency (% of the theoretical yield)
54.2 ± 2.2
70.7 ± 2.3
70.9 ± 3.5
72.5 ± 2.8
80.3 ± 3.1
59.4 ± 1.5
62.2 ± 1.9
62.1 ± 1.9
62.7 ± 2.5
Intake of hexoses (%)
85.1 ± 2.4
83.2 ± 2.5
83.8 ± 2.2
84.2 ± 2.6
83.8 ± 2.5
82.1 ± 2.4
82.8 ± 2.5
85.2 ± 2.5
85.1 ± 2.4
Intake of xylose (%)
65.3 ± 1.5
75.2 ± 1.8
77.2 ± 1.5
76.2 ± 1.4
77.5 ± 1.6
67.3 ± 1.5
74.5 ± 1.5
76.2 ± 1.5
71.3 ± 1.5
Enzymatic activation, Variant I
Ethanol content (g/L)
16.7 ± 0.5
22.5 ± 0.7
26.9 ± 1.2
23.6 ± 0.9
27.1 ± 1.2
17.5 ± 0.6
18.3 ± 0.7
18.1 ± 0.6
18.7 ± 0.8
Fermentation efficiency (% of the theoretical yield)
63.3 ± 1.8
80.1 ± 2.3
86.5 ± 2.1
83.4 ± 3.2
84.4 ± 3.7
65.8 ± 2.2
69.8 ± 2.7
69.3 ± 2.3
67.0 ± 2.9
Intake of hexoses (%)
91.6 ± 2.5
88.2 ± 2.2
90.3 ± 2.4
90.5 ± 2.5
95.5 ± 2.6
89.2 ± 2.5
88.6 ± 2.2
88.2 ± 2.2
87.5 ± 2.5
Intake of xylose (%)
74.5 ± 2.5
86.5 ± 2.6
88.2 ± 1.9
87.5 ± 1.8
89.5 ± 1.5
83.5 ± 1.6
80.5 ± 1.2
82.5 ± 1.5
81.5 ± 1.4
Enzymatic activation, Variant II
Ethanol content (g/L)
16.9 ± 0.5
22.1 ± 0.8
26.6 ± 1.5
22.7 ± 0.8
26.9 ± 1.5
18.1 ± 0.6
18.6 ± 0.8
19.2 ± 0.7
19.6 ± 0.7
Fermentation efficiency (% of the theoretical yield)
64.3 ± 1.6
78.5 ± 2.8
83.8 ± 4.7
80.3 ± 2.7
83.8 ± 4.2
68.0 ± 2.3
71.0 ± 2.8
73.6 ± 2.6
70.3 ± 2.5
Intake of hexoses (%)
91.3 ± 2.2
88.2 ± 2.6
92.0 ± 2.5
89.5 ± 1.8
93.0 ± 1.5
88.3 ± 2.2
88.5 ± 2.2
86.2 ± 2.5
88.2 ± 2.4
Intake of xylose (%)
74.9 ± 1.9
83.3 ± 2.2
88.1 ± 2.2
85.2 ± 2.2
89.5 ± 2.2
74.9 ± 1.9
80.8 ± 1.5
80.3 ± 2.0
80.5 ± 1.5
Results expressed as mean values ± SE (); mean values for initial fermentable sugar content with different letters are significantly different ( < 0.05, one-way ANOVA); mean values for ethanol content, fermentation efficiency, intake of hexoses, and intake of xylose with different letters are significantly different ( < 0.05, two-way ANOVA). Without enzymatic activation: inoculation with yeast Ethanol Red immediately after application of enzyme preparations. Enzymatic activation, Variant I: inoculation with yeast Ethanol Red after 6 h of enzymatic preparations action (Viscozyme 0.02 mL/g d.m.; Ultraflo Max 0.02 mL/g d.m., 40°C). Enzymatic activation, Variant II: inoculation with yeast Ethanol Red after 6 h of enzymatic preparations action (Viscozyme 0.015 mL/g d.m.; Ultraflo Max 0.015 mL/g d.m., 48–50°C).
