Anne Bergljot Falck-Ytter

• Klausen, Sarah Jasmin; Falck-Ytter, Anne Bergljot; Strætkvern, Knut Olav & Martín, Carlos (2023). Evaluation of the Extraction of Bioactive Compounds and the Saccharification of Cellulose as a Route for the Valorization of Spent Mushroom Substrate. Molecules. ISSN 1431-5157. 28(13). doi: 10.3390/molecules28135140. Fulltekst i vitenarkiv Vis sammendrag

  The extraction of bioactive compounds and cellulose saccharification are potential directions for the valorization of spent mushroom substrate (SMS). Therefore, investigating the suitability of different extraction methods for recovering bioactive compounds from SMS and how the extractionmaffects the enzymatic saccharification is of uppermost relevance. In this work, bioactive compounds were extracted from Pleurotus spp. SMS using four extraction methods. For Soxhlet extraction (SoE), a 40:60 ethanol/water mixture gave the highest extraction efficiency (EE) (69.9–71.1%) among the seven solvent systems assayed. Reflux extraction with 40:60 ethanol/water increased the extraction yield and EE compared to SoE. A shorter reflux time yielded a higher extraction of carbohydrates than SoE, while a longer time was more effective for extracting phenolics. The extracts from 240 min of reflux had comparable antioxidant activity (0.3–0.5 mM GAE) with that achieved for SoE. Ultrasound-assisted extraction (UAE) at 65 ◦C for 60 min allowed an EE (~82%) higher than that achieved by either reflux for up to 150 min or SoE. Subcritical water extraction (SWE) at 150 ◦C resulted in the best extraction parameters among all the tested methods. Vanillic acid and chlorogenic acid were the primary phenolic acids identified in the extracts. A good correlation between the concentration of caffeic acid and the antioxidant activity of the extracts was found. Saccharification tests revealed an enhancement of the enzymatic digestibility of SMS cellulose after the extraction of bioactive compounds. The findings of this initial study provide indications on new research directions for maximizing the recovery of bioactive compounds and fermentable sugars from SMS.

• Showkat, Muhammad Mir; Falck-Ytter, Anne Bergljot & Strætkvern, Knut Olav (2019). Phenolic acids in Jerusalem artichoke (Helianthus tuberosus L.): Plant organ dependent antioxidant activity and optimized extraction from leaves. Molecules. ISSN 1431-5157. 24(18). doi: 10.3390/molecules24183296. Fulltekst i vitenarkiv
• Ahmad, Rafi; Borowiec, Paulina; Falck-Ytter, Anne Bergljot & Strætkvern, Knut Olav (2017). Extraction, Solubility and Antimicrobial Activity of (-) Usnic Acid in Ethanol, a Pharmaceutically Relevant Solvent. Natural Product Communications. ISSN 1934-578X. 12(7), s. 1101–1104. doi: 10.1177/1934578x1701200725. Fulltekst i vitenarkiv Vis sammendrag

  Usnic acid (UA) is the most studied bioactive secondary metabolite from lichens. Recently, UA research has focused on its antibacterial activity. However, increased application in healthcare products of UA is hampered by low solubility in aqueous solutions. Here, we report ethanol both as an alternative extraction solvent to acetone and as a pharmaceutically relevant solvent for future formulations. Dried samples of the abundant reindeer lichen (Cladonia stellaris) were extracted in a 23 factorial design using either ethanol or acetone, varying both time and solvent-to-dry mass ratio. In both extracts, UA was the predominant compound as shown by two-dimensional thin-layer chromatography (TLC). In a disc diffusion assay, both extracts demonstrated similar antibacterial susceptibility towards Gram-positive (Bacillus subtilis and Staphylococcus aureus), while showing little to no activity against Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa). Among a range of pharmaceutically relevant solvents tested, UA was only soluble in ethanol (at concentrations up to 1-2 mg mL-1).

• Rahman, Mahfizur; Falck-Ytter, Anne Bergljot; Antonsen, Øyvind Gunnar & Strætkvern, Knut Olav (2015). Reindeer lichen (Cladonia stellaris) from a Norwegian mountain region as a sustainable source of usnic acid. International Journal of Applied Research in Natural Products. 8(3), s. 17–23. Fulltekst i vitenarkiv
• Bril'kov, Maxim; Falck-Ytter, Anne Bergljot & Strætkvern, Knut Olav (2015). Evaluation of methods for reducing the ash content of waste frying oil processed to biofuel oil. Fuel processing technology. ISSN 0378-3820. 134, s. 487–493. doi: 10.1016/j.fuproc.2015.03.008. Fulltekst i vitenarkiv

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• Klausen, Sarah J.; Falck-Ytter, Anne Bergljot; Strætkvern, Knut Olav & Martín, Carlos (2023). Extraction of bioactive compounds and saccharification of polysaccharides for valorization of spent mushroom substrate following a biorefinery approach. Fulltekst i vitenarkiv
• Chhetri, Jyoti; Falck-Ytter, Anne Bergljot & Strætkvern, Knut Olav (2023). Phenolic acids from the leaves of Jerusalem artichoke (Helianthus tuberosus L.): Effect of drying, intensification, and solvent system on yield and antioxidant activity. Fulltekst i vitenarkiv Vis sammendrag

  The perennial and tuberous Jerusalem artichoke (JA) is a hardy vegetable growing under almost any condition. Besides its inulin-rich underground tubers, the sunflower-like plant’s aerial parts (leaf, flower, stem) are a rich yet unexploited source of bioactive phytochemicals. The leaves are abundant in various phenolic acids having antioxidant activity. In this study, leaves of JA were harvested from full-grown plants (> 2 m) and subjected to conventional and non-conventional solvent extraction techniques to maximize the yield of phenolic acids. Harvested leaves were either dried or used as fresh. The two solvent systems were aqueous ethanol (55 %) and choline chloride/glucose/water (1:3:30), a natural deep eutectic solvent (NADES) acting through multiple hydrogen bond formation. The techniques compared were maceration at room temperature (ME) and ultrasound-assisted extraction (UAE). For each solvent system, the effect on total phenolics yield (TPC, mg gallic acid eqv./ g dry substance) was tested with both fresh and dried leaves in a two-level full factorial design (n=14) through a combination of varying extraction time (20-60 min) and liquid-to-solids ratio (20-50:1). The extraction output was also assayed as the ferric reducing antioxidant power (FRAP, mM Fe2+ eqv. /g DS). The main findings are: (1) The drying of JA leaves compared to fresh material improved the TPC yield (3-fold) and FRAP activity (10-20 fold) in aqueous ethanol irrespective of ME and UAE; (2) NADES was a better solvent for extraction giving 5-8 fold higher TPC yields and FRAP activities than with ethanol; (3) the additive effect of UAE was significant (approx. 40 %) only for fresh leaves in NADES, with maximum study values of TPC (15.7) and FRAP (17.7). Overall, drying of the biomass helps the extraction output, likely due to the destabilization and rupture of the leaf cell matrix, improving the mass transfer of phenolic compounds. On the other hand, extraction in NADES – a green solvent, is less dependent on the state of the leaves, probably due to the swelling of cells from water uptake and the subsequent improved mobilization and mass transfer of solutes.

• Strætkvern, Knut Olav; Davenne, Tamara; Falck-Ytter, Anne Bergljot & Thøgersen, Jesper (2015). Screening by DoE of critical chromatographic variables in the capture of anionic and cationic proteins from industrial potato fruit juice. Fulltekst i vitenarkiv Vis sammendrag

  Ion exchange chromatography is usually predictable in its outcome when setting the system pH at an appropriate distance from the target protein pI. But how predictable is that with a complex feed like potato fruit juice (PFJ)? A voluminous by-product from starch processing, rich in minerals and phytochemicals, PFJ contains proteins (about 1.5%) of both anionic (patatin) and cationic (potato protease inhibitors, PPI) types. In studies to determine optimum capture of both, we examined the influence of critical adsorption factors (pH, ionic strength, flow rate, sample load). Design of Experiments (DoE) was used with two or three factor levels to screen for main effects and possible factor interactions on the protein yield. The patatin group (pI 4.5-5.2) and the PPI group (pI ca. 6.5-9) were captured from PFJ on bioprocess ion exchange resins, anionic and cationic respectively, using lab scale columns (1, 5 and 25ml). Lab scale-up of the chromatography to validate the capture process was facilitated with a 250 ml radial flow chromatography (RFC) column. For the PPI capture, the process was transferred to a 10 liter pilot scale RFC column in a starch processing plant. Analysis of patatin capture showed that ionic strength was a more determinative factor than pH, where optimum binding was favored around pH 7-7.5 and 6-7 mS/cm. Screening of PPI capture revealed that acidic pH 3.5-4 was advantageous, as expected from the overall pI-values. However, ionic strength above 7 mS/cm significantly improved the protein yield, which may indicate favorable ionic shielding effects. In both types of chromatography, the loading flow rate, instead of impairing the mass transfer, showed a positive correlation with protein yield over the range 250-650 cm/h and 450-900 cm/h, respectively. This observation made use of RFC even more desirable, since the column geometry provides low back pressures at high flow rates. However, in the RFC scale-up of patatin capture on anion exchanger, significant interaction effects between sample load (negative) and flow rate (positive) was observed. In the RFC scale-up of PPI capture on cation exchanger, although binding kinetics is rapid, extended column residence time (0.4 vs 0.8 min) showed to be a more important factor than keeping a high flow rate during loading. This was confirmed when transferring from lab to pilot scale RFC columns, both with 12 cm bed depth. Overall, optimum conditions for capture of potato proteins were efficiently obtained through the screening process, resulting in consistent protein yields. KEY WORDS: Potato proteins - Design of experiments - Ion exchange chromatography - Radial flow column HIGHLIGHTS: * Potato fruit juice is an interesting system to for capture of high abundance proteins. * With DoE unexpected interaction effects were observed for ionic strength and flow rate * Radial flow columns enhanced capture probably due to better sample-resin interaction.

• Falck-Ytter, Anne Bergljot & Aaseth, Jan (2014). Du kan ikke leve uten disse syrene. [Journal]. Bedre helse. Fulltekst i vitenarkiv

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