Production of Monomeric Aromatic Compounds from Oil Palm Empty Fruit Bunch Fiber Lignin by Chemical and Enzymatic Methods
Table 1
Effect of pH, solid content, enzyme concentration, time, and temperature on oxidation products yield from enzyme cutinase hydrolysis on lignin (; ).
(a) pH
Compounds
pH 7
pH 8
pH 10
pH 12
Yield
Recovery
Yield
Recovery
Yield
Recovery
Yield
Recovery
Hydroxybenzoic acid
153.14 ± 3.07
7.66 ± 0.15
165.30 ± 2.51
8.27 ± 0.13
162.72 ± 4.13
8.14 ± 0.21
156.14 ± 4.03
7.81 ± 0.20
Syringaldehyde
13.89 ± 0.22
0.70 ± 0.01
14.94 ± 0.36
0.75 ± 0.02
13.93 ± 0.90
0.70 ± 0.05
2.71 ± 0.60
0.14 ± 0.03
Vanillin
3.33 ± 0.58
0.17 ± 0.03
8.02 ± 0.32
0.40 ± 0.02
8.49 ± 0.09
0.42 ± 0.01
9.55 ± 0.53
0.48 ± 0.03
p-Coumaric acid
7.04 ± 0.21
0.35 ± 0.01
7.72 ± 0.20
0.39 ± 0.01
8.22 ± 1.18
0.41 ± 0.06
6.83 ± 0.45
0.34 ± 0.02
Ferulic acid
13.80 ± 0.63
0.69 ± 0.03
14.06 ± 0.13
0.70 ± 0.07
13.68 ± 0.38
0.68 ± 0.02
7.78 ± 0.39
0.39 ± 0.02
Note. Different alphabets in the same row indicated that there are significant differences () between the yields from different pH. Different alphabets in the same row indicated that there are significant differences () between the recoveries from different pH.
(b) Lignin concentration
Compounds
2% wt.
5% wt.
8% wt.
10% wt.
Yield
Recovery
Yield
Recovery
Yield
Recovery
Yield
Recovery
Hydroxybenzoic acid
165.30 ± 2.51
8.27 ± 0.13
454.14 ± 11.66
9.08 ± 0.23
642.83 ± 14.45
8.04 ± 0.18
733.19 ± 26.68
7.33 ± 0.27
Syringaldehyde
14.94 ± 0.36
0.75 ± 0.02
49.70 ± 2.88
0.99 ± 0.06
70.19 ± 3.31
0.88 ± 0.04
77.78 ± 3.78
0.79 ± 0.04
Vanillin
8.02 ± 0.32
0.40 ± 0.02
16.65 ± 1.07
0.33 ± 0.02
22.80 ± 1.04
0.29 ± 0.01
25.39 ± 0.78
0.25 ± 0.08
p-Coumaric acid
7.72 ± 0.20
0.39 ± 0.01
19.07 ± 0.67
0.38 ± 0.01
27.06 ± 1.20
0.34 ± 0.02
29.13 ± 2.72
0.29 ± 0.03
Ferulic acid
14.06 ± 0.13
0.70 ± 0.07
39.02 ± 1.42
0.78 ± 0.03
50.19 ± 1.23
0.63 ± 0.02
56.95 ± 2.52
0.57 ± 0.03
Note. Different alphabets in the same row indicated that there are significant differences () between the yields from different lignin concentration. Different alphabets in the same row indicated that there are significant differences () between the recoveries from different lignin concentration.
(c) Enzyme concentration
Compounds
0.625 mL cutinase g−1 lignin
1.25 mL cutinase g−1 lignin
1.875 mL cutinase g−1 lignin
2.5 mL cutinase g−1 lignin
Yield
Recovery
Yield
Recovery
Yield
Recovery
Yield
Recovery
Hydroxybenzoic acid
642.83 ± 14.45
8.04 ± 0.18
557.80 ± 12.76
6.97 ± 0.16
569.66 ± 11.48
7.12 ± 0.14
542.94 ± 27.88
6.79 ± 0.35
Syringaldehyde
70.19 ± 3.31
0.88 ± 0.04
53.94 ± 1.20
0.67 ± 0.02
54.09 ± 3.00
0.68 ± 0.04
54.94 ± 4.67
0.69 ± 0.06
Vanillin
22.80 ± 1.04
0.29 ± 0.01
21.68 ± 0.48
0.27 ± 0.01
21.87 ± 0.71
0.27 ± 0.01
20.77 ± 1.12
0.26 ± 0.01
p-Coumaric acid
27.06 ± 1.20
0.34 ± 0.02
22.81 ± 1.44
0.29 ± 0.02
21.78 ± 0.65
0.27 ± 0.01
19.69 ± 0.25
0.25 ± <0.00
Ferulic acid
50.19 ± 1.23
0.63 ± 0.02
46.94 ± 1.59
0.59 ± 0.02
46.33 ± 3.56
0.58 ± 0.04
46.93 ± 2.81
0.59 ± 0.04
Note. Different alphabets in the same row indicated that there are significant differences () between the yields from different enzyme concentration. Different alphabets in the same row indicated that there are significant differences () between the recoveries from different enzyme concentration.
(d) Time
Compounds
24 hours
48 hours
72 hours
Yield
Recovery
Yield
Recovery
Yield
Recovery
Hydroxybenzoic acid
642.83 ± 14.45
8.04 ± 0.18
592.59 ± 35.11
7.41 ± 0.44
649.62 ± 21.35
8.12 ± 0.27
Syringaldehyde
70.19 ± 3.31
0.88 ± 0.04
28.23 ± 0.55
0.35 ± 0.01
34.03 ± 2.01
0.43 ± 0.03
Vanillin
22.80 ± 1.04
0.29 ± 0.01
26.61 ± 1.80
0.33 ± 0.02
32.64 ± 2.35
0.41 ± 0.03
p-Coumaric acid
27.06 ± 1.20
0.34 ± 0.02
22.08 ± 0.59
0.28 ± 0.01
23.76 ± 1.63
0.30 ± 0.02
Ferulic acid
50.19 ± 2.23
0.63 ± 0.02
41.77 ± 0.90
0.52 ± 0.01
43.39 ± 1.10
0.54 ± 0.01
Note. Different alphabets in the same row indicated that there are significant differences () between the yields from different time. Different alphabets in the same row indicated that there are significant differences () between the recoveries from different time.
(e) Temperature
Compounds
40°C
55°C
65°C
Yield
Recovery
Yield
Recovery
Yield
Recovery
Hydroxybenzoic acid
492.54 ± 38.89
6.16 ± 0.49
557.80 ± 12.76
6.97 ± 0.16
498.88 ± 42.35
6.24 ± 0.53
Syringaldehyde
35.22 ± 2.01
0.44 ± 0.03
53.94 ± 1.20
0.67 ± 0.02
60.12 ± 4.26
0.75 ± 0.05
Vanillin
15.99 ± 0.74
0.20 ± 0.01
21.68 ± 0.50
0.27 ± 0.01
23.44 ± 2.21
0.29 ± 0.03
p-Coumaric acid
13.94 ± 1.29
0.17 ± 0.02
22.81 ± 1.44
0.29 ± 0.02
13.01 ± 2.15
0.16 ± 0.03
Ferulic acid
37.81 ± 2.35
0.47 ± 0.03
46.94 ± 1.59
0.59 ± 0.02
31.74 ± 2.80
0.40 ± 0.04
Note. Different alphabets in the same row indicated that there are significant differences () between the yields from different temperature. Different alphabets in the same row indicated that there are significant differences () between the recoveries from different temperature. Yield of oxidation products was expressed in unit part per million (ppm), while recovery of oxidation products from lignin was expressed in unit milligram per gram of lignin (mg g−1 lignin).