| 1. |
- Ekman, Anna, et al.
(författare)
-
Bioresource utilisation by sustainable technologies in new value-added biorefinery concepts - two case studies from food and forest industry
- 2013
-
Ingår i: Journal of Cleaner Production. - : Elsevier BV. - 0959-6526 .- 1879-1786. ; 57, s. 46-58
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents a trans-disciplinary assessment of new and innovative biorefinery concepts producing high-value chemical compounds from residues from agriculture, food and forest industries. There is a significant potential of biomass residues in Sweden suitable for the extraction of various compounds, including upgrading by biocatalytic processes, in addition to current energy generation. Two examples presented are quercetin extracted from onion waste by pressurised hot water in conjunction with enzymatic hydrolysis, and betulin from birch bark extracted by liquid CO2 containing ethanol. Inherent in these two extraction processes and production routes is the ability to show good environmental performance from a life cycle perspective. Extraction of high-value compounds also provides possibilities for innovation in the current agricultural, food and forest industry potentially leading to socio-economical benefits. (C) 2013 The Authors. Published by Elsevier Ltd. All rights reserved.
|
|
| 2. |
- Lindahl, Sofia, et al.
(författare)
-
Exploring the possibility of using a thermostable mutant of β-glucosidase for rapid hydrolysis of quercetin glucosides in hot water
- 2010
-
Ingår i: Green Chemistry. - : The Royal Society of Chemistry. - 1463-9262 .- 1463-9270. ; 12:1, s. 159-168
-
Tidskriftsartikel (refereegranskat)abstract
- The antioxidant quercetin was extracted from yellow onion waste and converted to its aglycone form by a combination of subcritical water extraction and enzymatic hydrolysis. The hydrolytic step was catalysed by a double residue (N221S, P342L) mutant of the thermostable beta-glucosidase (TnBgl1A), isolated from the thermophile Thermotoga neapolitana and cloned and produced in E. coli. The activity of wt TnBgl1A was shown to be dependent on the position of the glucosylation on the quercetin backbone, favouring hydrolysis of quercetin-4'-glucoside over quercetin-3-glucoside. The mutated variant of the enzyme harboured a mutation in the +2 sub-site (N221S) and showed increased catalytic efficiency in quercetin-3-glucoside hydrolysis and also to a certain extent hydrolysis of quercetin-4'-glucoside. The mutated enzyme was used directly in yellow onion extracts, prepared by subcritical water extraction, resulting in complete hydrolysis of the glucosylated flavonoids quercetin-3,4'-diglucoside, quercetin-4'-glucoside, quercetin-3-glucoside, isorhamnetin-4'-glucoside and isorhamnetin-3,4'-diglucoside. To complete hydrolysis within five minutes, 3 mg of TnBgl1A_N221S was used per gramme of onion (dry weight). A life cycle assessment was done to compare the environmental impact of the new method with a conventional solid-liquid extraction-and-hydrolysis method utilising aqueous methanol and hydrochloric acid. Comparison of the methods showed that the new method is preferable regarding primary energy consumption and global warming potential. Another advantage of this method is that handling of toxic chemicals (methanol and HCl) is avoided. This shows that combined subcritical water extraction/enzyme hydrolysis is both a fast and sustainable method to obtain quercetin from onion waste.
|
|
| 3. |
|
|
| 4. |
|
|
| 5. |
- Turner, Charlotta, et al.
(författare)
-
Subcritical water extraction and beta-glucosidase-catalyzed hydrolysis of quercetin glycosides in onion waste
- 2006
-
Ingår i: Green Chemistry. - : Royal Society of Chemistry (RSC). - 1463-9262 .- 1463-9270. ; 8:11, s. 949-959
-
Tidskriftsartikel (refereegranskat)abstract
- Onion waste is a renewable raw material, rich in different molecular species of the antioxidant quercetin. To utilize this resource, an environmentally sustainable procedure has been developed, using pressurized hot water to extract the quercetin species, followed by biocatalytic conversion of the quercetin glycosides to quercetin and carbohydrates. Two different recombinantly expressed thermostable beta-glucosidases, Thermotoga neapolitana beta-glucosidase A and B, were utilized as catalysts. These enzymes maintain activity at temperatures around 90 degrees C, and are therefore ideal to use in combination with hot water extraction. Our results, based on experimental design, showed that they converted quercetin glycosides to active quercetin in less than 10 min reaction time in water at 90 degrees C, pH 5.0. Experimental design showed that the optimal extraction conditions included three 5 min extraction cycles with water at 120 degrees C and 50 bars, giving a total extraction time of 15 min. Several different types of quercetin and isorhamnetin glycosides as well as kaempferol were detected in onion waste using LC-MS/MS analysis. After converting the different glycosidic compounds to their respective aglycones, the quercetin content was 10 to 50 mg g(-1) dry weight of onion waste (RSD 8%). In summary, our research demonstrates that subcritical water extraction followed by beta-glucosidase-catalyzed hydrolysis is a rapid method to determine the content of quercetin and isorhamnetin in onion samples, and is environmentally sustainable as it only uses water as solvent and enzymes as catalysts.
|
|
