Sarah Jasmin Klausen

• Akter, Afrina; Klausen, Sarah Jasmin; Soto, Luis Alejandro Romero; Díaz, Francisco; Domínguez, Herminia & Xiong, Shaojun [Show all 8 contributors for this article] (2025). Comparative extraction of bioactive compounds from spent mushroom substrates of Lentinula edodes and Pleurotus ostreatus using subcritical water and pressurized ethanol. Industrial crops and products (Print). ISSN 0926-6690. 235. doi: 10.1016/j.indcrop.2025.121750. Full text in Research Archive Show summary

  This study aimed to assess subcritical water extraction (SWE) and pressurized ethanol extraction (PEE) for recovering bioactive compounds from spent mushroom substrate (SMS) derived from shiitake and oyster mushrooms. The extraction of bioactive compounds can facilitate the valorisation of SMS, an increasingly important waste stream whose management and disposal pose challenges for both mushroom producers and the environment. A 32 experimental design, using three temperatures (125, 150, and 175 °C) and three holding times (0, 15, and 30 min) was used in SWE. PEE was run at a single temperature (175 °C) and two holding times (0 and 15 min). The experimental results revealed that the highest extraction yield was achieved in shiitake SMS using SWE at 175 °C and 15 min. In most SWE conditions, shiitake SMS yielded higher concentrations of total phenolic compounds, total carbohydrates, and β-glucans compared to oyster mushroom SMS. Ascorbic acid, vanillic acid, protocatechuic acid, and gallic acid were the most abundant phenolic acids identified in both extracts. The SWE extracts of shiitake SMS exhibited higher DPPH and FRAP antioxidant activity than those of oyster mushroom SMS, and this activity increased with increasing temperature and time. PEE extracts exhibited higher DPPH and TEAC antioxidant activity for oyster mushroom SMS compared to shiitake SMS and showed a negative trend with increasing extraction time at 175 °C for both SMS. Our results show that SWE and PEE are viable methods for extracting bioactive compounds from SMS.

• Klausen, Sarah Jasmin; Soto, Luis Alejandro Romero; Liaqat, Ayesha; Dehghanmanshadi, Zahra; Strætkvern, Knut Olav & Xiong, Shaojun [Show all 7 contributors for this article] (2025). Biorefining spent substrates of shiitake (Lentinula edodes) and oyster mushroom (Pleurotus ostreatus): enzymatic saccharification of cellulose and xylan, with lignin recovery from residues. Bioengineered. ISSN 2165-5979. 16(1). doi: 10.1080/21655979.2025.2536443. Full text in Research Archive Show summary

  Spent mushroom substrate (SMS), the main by-product of mushroom cultivation, is a source of sugars that can be released by saccharification. This work aimed at investigating the enzymatic saccharification of the polysaccharides of the SMS of shiitake (Lentinula edodes) and oyster mushroom (Pleurotus ostreatus) and exploring the lignin extraction from the saccharification residues. First, analytical enzymatic saccharification (AES) with a cellulase cocktail and an experimental hemicellulase-rich preparation was applied. AES revealed higher digestibility of both polysaccharides for shiitake SMS than for oyster mushroom SMS. Using the cellulase cocktail, shiitake SMS resulted in a digestibility above 80% and 70% (w/w) for cellulose and xylan, respectively, while the maximum values for oyster mushroom SMS were 52% and 32% (w/w). The experimental enzyme preparation resulted in lower cellulose digestibility and higher xylan digestibility. Still, the saccharification trend between the two SMS types remained unchanged. To enhance the enzymatic saccharification of oyster mushroom SMS, hydrothermal treatment was applied. The treatment improved the enzymatic digestibility of cellulose by up to 84%. A validation experiment at larger scale showed that hydrothermally treated oyster mushroom SMS had a comparable overall conversion with non-treated shiitake SMS. Following a biorefinery strategy, lignin was extracted from the residues of the preparative enzymatic saccharification using the green solvent γ-valerolactone under different temperatures and holding times. The extracted product contained 98.8% lignin and did not contain cellulose or xylan. The results of this study provide the grounds for biorefinery processes enabling recovery of bioactive compounds, fermentable sugars, and high-quality lignin from SMS

• Semaan, Georgeio; Klausen, Sarah Jasmin; Martín, Carlos; Jørgensen, Kåre Bredeli & Kumar, Gopalakrishnan (2025). Fractionation and characterization of multi-feedstock lignocellulosic biomass via two-stage pretreatment. Biomass Conversion and Biorefinery. ISSN 2190-6815. 15, p. 18925–18945. doi: 10.1007/s13399-025-06576-8. Full text in Research Archive Show summary

  A two-stage pretreatment toward lignocellulosic biomass fractionation was devised. The process consisted of dilute acid hydrolysis using oxalic acid, followed by oxalic acid–assisted ethanol organosolv pretreatment. A biomass mixture consisting of four regional lignocellulosic materials, namely, brewer’s spent grain, tomato waste biomass, cucumber waste biomass, and spent coffee grounds, was used. In the first stage, the optimum mixture composition was determined using a full factorial design coupled with a simplex-centroid design. The interactive effects of the solid-to-liquid ratio, holding time, acid type, and concentration were also considered. In the attempt to lower solid yields and increase hemicellulose dissolution, elevated levels of furfural (15.73 g/L) and 5-hydroxymethylfurfural (8.56 g/L) were formed, due to increased pretreatment severity (180 min, 135C, 83.15 mg oxalic acid/g biomass, and 100 g biomass/L). The solid yield achieved was 50.53%. In the second stage, the effect of ethanol-to-water solvent ratio, holding time, and temperature were investigated using a central composite experimental design. Solid yields ranged between 72.57 and 85.20% (w/w), mainly due to lignin removal. Pretreatment with 75% (v/v) ethanol at 120 min and 190 °C resulted in the highest lignin recovery (44.69%). Post-experimental verification runs were performed to evaluate the validity of the response surface models with a maximum error of 15.17%. Characterization by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and heteronuclear single quantum coherence spectroscopy (HSQC) were conducted to assess biomass fraction integrity and structural changes during pretreatment.

• Chen, Feng; Martín, Carlos; Jönsson, Leif J.; Gandla, Madhavi Latha; Klausen, Sarah Jasmin & Soto, Luis Alejandro Romero [Show all 7 contributors for this article] (2024). Mild thermal treatment assists fungal preprocessing of softwood sawdust for production of fermentable sugar. Industrial crops and products (Print). ISSN 0926-6690. 223. doi: 10.1016/j.indcrop.2024.120284. Full text in Research Archive Show summary

  Preheating with hot air at 85 – 125 ◦ ◦ C was evaluated for its effectiveness in removing terpenes and terpenoids in softwood sawdust, thereby enhancing fungal preprocessing and subsequent saccharification of softwood-based mushroom substrates. Sawdust from pine (Pinus sylvestris L.) and spruce (Picea abies (L.) H. Karst.) was preheated prior to shiitake (Lentinula edodes (Berk.) Pegler) cultivation. Preheating removed up to 96 % of terpenes in pine- based substrates and up to 50 % in spruce-based substrates. Additionally, preheating decreased total terpenoids content in spruce by up to 78 %. For the pine-based substrate, the mild heating generally led to faster colonisation and improved mushroom yield, with the fastest mycelia colonisation and highest yield observed for 105 C treatment. This temperature was associated with the lowest content of total terpenes and absence of major monoterpenes. The content of terpenes and terpenoids continued to decrease during cultivation, alongside fungal degradation of lignocellulose. As a result of more extensive lignin degradation, the enzymatic digestibility of cellulose was higher for spruce-based spent mushroom substrate than for pine-based one (up to 89 % vs. 49 % conversion). Enzymatic digestibility showed a negative correlation with the α correlation with increasing preheating temperatures.

• 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. Full text in Research Archive Show summary

  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.

• Martín, Carlos; Xiong, Shaojun; Passoth, Volkmar; Põldmaa, Kadri; Solberg, Svein Øivind & Hultberg, M [Show all 13 contributors for this article] (2023). Mushrooms for enhanced agriculture sustainability the MUSA concept. C3-Bioeconomy Circular and Sustainable Bioeconomy. p. 131–146. Full text in Research Archive Show summary

  The project MUSA – MUshrooms for Sustainable Agriculture is an effort to use mushroom-based processes to enhance agriculture sustainability in Nordic and Baltic countries. The project covers both the production of fruitbodies of edible fungi and the upgrading of the exhausted substrate from mushroom cultivation. The suitability of residues generated locally for producing edible mushrooms is investigated. Residues from Nordic agriculture and sub-utilized streams from forestry management, as well as wood processing by-products, are evaluated as the substrate base for producing shiitake (Lentinula edodes) and oyster (Pleurotus spp.) mushrooms. The project explores the potential of spent mushroom substrate (SMS) to support food production. SMS prospective as source of bioactive compounds and sugars is evaluated. MUSA investigates the suitability of SMS hydrolysates as carbon sources for cultivating oleaginous yeast to produce microbial oil suitable for human consumption. Using SMS for substituting mineral fertilizers and providing wastewater bioremediation solutions is also assessed

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• Klausen, Sarah Jasmin; Akter, Afrina; Soto, Luis Alejandro Romero; Martín, Carlos; F., Díaz, & H., Domínguez, [Show all 8 contributors for this article] (2025). Turning trash into treasure: Pressurized liquid extraction as a method for extracting bioactive compounds from spent mushroom substrate. Full text in Research Archive
• Soto, Luis Alejandro Romero; Klausen, Sarah Jasmin; Strætkvern, Knut Olav; Martín, Carlos; Shaojun, Xiong, & A., Liaqat, [Show all 7 contributors for this article] (2025). Deciphering biorefinery valorization routes for spent mushroom substrates: enzymatic saccharification and lignin recovery. Full text in Research Archive
• Klausen, Sarah Jasmin; Diaz, F; Liaqat, Ayesha; Díaz-Reinoso, B; Torres, MD & Flórez-Fernández, N [Show all 8 contributors for this article] (2024). Recovery of antioxidant compounds from Lentinula edodes and Hericium erinaceus spent mushroom substrate by sequential extraction with microwave hydrodiffusion and gravity and supercritical carbon dioxide. Full text in Research Archive
• Akter, Afrina; Klausen, Sarah Jasmin; Romero-Soto, Luis Alejandro; Diaz, F; Dominguez, Herminia & Strætkvern, Knut Olav [Show all 7 contributors for this article] (2024). Pressurized liquid extraction of bioactive compounds from spent mushroom substrate of Lentinula edodes and Pleurotus ostreatus. Full text in Research Archive

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