| 1. |
- Harirchi, Sharareh, et al.
(författare)
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Microbiological insights into anaerobic digestion for biogas, hydrogen or volatile fatty acids (VFAs) : a review
- 2022
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Ingår i: Bioengineered. - : Taylor and Francis Ltd.. - 2165-5979 .- 2165-5987. ; 13:3, s. 6521-6557
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Tidskriftsartikel (refereegranskat)abstract
- In the past decades, considerable attention has been directed toward anaerobic digestion (AD), which is an effective biological process for converting diverse organic wastes into biogas, volatile fatty acids (VFAs), biohydrogen, etc. The microbial bioprocessing takes part during AD is of substantial significance, and one of the crucial approaches for the deep and adequate understanding and manipulating it toward different products is process microbiology. Due to highly complexity of AD microbiome, it is critically important to study the involved microorganisms in AD. In recent years, in addition to traditional methods, novel molecular techniques and meta-omics approaches have been developed which provide accurate details about microbial communities involved AD. Better understanding of process microbiomes could guide us in identifying and controlling various factors in both improving the AD process and diverting metabolic pathway toward production of selective bio-products. This review covers various platforms of AD process that results in different final products from microbiological point of view. The review also highlights distinctive interactions occurring among microbial communities. Furthermore, assessment of these communities existing in the anaerobic digesters is discussed to provide more insights into their structure, dynamics, and metabolic pathways. Moreover, the important factors affecting microbial communities in each platform of AD are highlighted. Finally, the review provides some recent applications of AD for the production of novel bio-products and deals with challenges and future perspectives of AD. © 2022 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.
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| 2. |
- Moshtaghian, Hanieh, et al.
(författare)
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Application of Oyster Mushroom Cultivation Residue as an Upcycled Ingredient for Developing Bread
- 2022
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Ingår i: Applied Sciences. - : MDPI. - 2076-3417. ; 12:21
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Tidskriftsartikel (refereegranskat)abstract
- Oyster mushroom (OM) cultivation generates residue that needs to be managed; otherwise, it will be converted into waste. One of the substrates for OM cultivation is the food industry by-product, e.g., a mixture of the brewer’s spent grain (BSG) and wheat bran. This study assesses the OM cultivation residue’s physical and nutritional characteristics as a potential upcycled food ingredient and also considers developing bread from this cultivation residue. The OM was cultivated in a mixture of 55% BSG and 45% wheat bran. After the OM harvest, the cultivation residue (mixture of BSG, wheat bran and mycelium) had a lighter colour and a pleasant aroma compared to the initial substrate. It contained protein (10.8%) and had high niacin (42.4 mg/100 g), fibre (59.2%) and beta-glucan (6.6%). Thiamine, riboflavin and pyridoxine were also present in the cultivation residue. The bread was developed from 50% cultivation residue and 50% wheat flour, and its scores for darkness, dryness, sponginess, sour taste, bitter aftertaste, and aromatic aroma differed from white bread (p-value < 0.05). However, its overall acceptability and liking scores were not significantly different from white bread (p-value > 0.05). Therefore, this OM cultivation residue can be used as a nutritious ingredient; nevertheless, product development should be further explored.
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| 3. |
- Mousavi, Najmeh, et al.
(författare)
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Bioconversion of Carrot Pomace to Value-Added Products : Rhizopus delemar Fungal Biomass and Cellulose
- 2023
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Ingår i: FERMENTATION-BASEL. - : MDPI AG. - 2311-5637. ; 9:4
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Tidskriftsartikel (refereegranskat)abstract
- Carrot pomace (CP) which is generated in a large volume in the juice production process, is rich in cellulose, hemicellulose, sugars, pectin, and minerals. However, in many previous investigations, only cellulose was purified and utilized while other components of CP were discarded as waste. Here, CP was valorized into fungal biomass and cellulose with the aim of utilizing all the CP components. Enzymatic pretreatments were applied to solubilize the digestible fraction of CP including hemicellulose, pectin, sucrose, and other sugars for fungal cultivation, while cellulose remained intact in the solid fraction. The dissolved fraction was utilized as a substrate for the cultivation of an edible fungus (Rhizopus delemar). Fungal cultivation was performed in shake flasks and bench-scale bioreactors. The highest fungal biomass concentration was obtained after pretreatment with invertase (5.01 g/L) after 72 h of cultivation (36 and 42% higher than the concentrations obtained after hemicellulase and pectinase treatments, respectively). Invertase pretreatment resulted in the hydrolysis of sucrose, which could then be taken up by the fungus. Carbohydrate analysis showed 28-33% glucan, 4.1-4.9% other polysaccharides, 0.01% lignin, and 2.7-7% ash in the CP residues after enzymatic pretreatment. Fourier transform infrared spectroscopy and thermogravimetric analysis also confirmed the presence of cellulose in this fraction. The obtained fungal biomass has a high potential for food or feed applications, or as a raw material for the development of biomaterials. Cellulose could be purified from the solid fraction and used for applications such as biobased-textiles or membranes for wastewater treatment, where pure cellulose is needed.
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| 4. |
- Parchami, Mohsen, et al.
(författare)
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Aqueous ethanol organosolv process for the valorization of Brewer’s spent grain (BSG)
- 2022
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Ingår i: Bioresource Technology. - : Elsevier. - 0960-8524 .- 1873-2976. ; 362
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Tidskriftsartikel (refereegranskat)abstract
- Brewers spent grain (BSG), the main solid byproduct of brewing, is annually generated by ca 37 million tons worldwide, which due to limited application, mostly ends up in landfills. This study aims to separate BSG’s fractions (lignin, cellulose, and hemicellulose) by ethanol organosolv pretreatment. Lignin-rich fractions were recovered using a two-step separation technique. The effects of temperature, retention time, and ethanol concentration on the quantity and quality of fractions were studied. The temperature considerably impacted the quality and quantity of obtained fractions, while other parameter effects greatly depended on the temperature. Substantial hemicellulose removal (90 %) along with lignin removal (56 %) and recovery (57 %) were obtained at 180 °C. The highest lignin purity (95 %) was obtained at the pretreatment conditions of 180 °C, 120 min, and 50 % ethanol concentration. This work provides an alternative route for BSG utilization, mitigating its environmental impact while enhancing the economy of a brewery.
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| 5. |
- Parchami, Mohsen, et al.
(författare)
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Biovalorization of brewer's spent grain as single-cell protein through coupling organosolv pretreatment and fungal cultivation
- 2023
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Ingår i: Waste Management. - 0956-053X .- 1879-2456. ; 169, s. 382-391
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Tidskriftsartikel (refereegranskat)abstract
- Brewer's spent grain (BSG) is a clean byproduct from the food sector, comprising 85% of the brewing process solid byproducts. BSG is mainly used as low-quality animal feed and often ends up in landfills due to its short shelf life. However, considering its abundant availability and high nutritional content, BSG holds the potential for biorefineries to produce valuable products. The recalcitrant nature of BSG poses a challenge, requiring pretreatment steps. Therefore, this study focused on valorizing BSG obtained from organosolv pretreatment by producing food- and feed-grade single-cell protein (SCP). The BSG was subject to organosolv pretreatment at 180C for 2 h with 50% v/v ethanol as solvent. Filamentous fungi N. intermedia and A. oryzae were cultivated on as-received and different fractions of organosolv-treated BSG to evaluate the effect of factors such as pretreatment, fungal strain, pretreated fraction content, and substrate loading on fungal biomass yield, biomass composition (protein content), and metabolite production. A. oryzae cultivation on all tested substrates yielded 7%-40% more biomass than N. intermedia. Cultivating A. oryzae on organosolv liquor resulted in the highest biomass protein content (44.8% ± 0.7%) with a fungal biomass concentration of 5.1 g/L. A three-fold increase in the substrate loading increased the ethanol-to-substrate yield by 50%, while protein content was decreased by 23%. Finally, a biorefinery concept was proposed to integrate the organosolv pretreatment of BSG with fungal cultivation for maximum yield of SCP while obtaining other products such as lignin and ethanol, providing a sustainable rout for managing BSG.
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| 6. |
- Parchami, Mohsen, et al.
(författare)
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Brewing Process Development by Integration of Edible Filamentous Fungi to Upgrade the Quality of Brewer’s Spent Grain (BSG)
- 2021
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Ingår i: BioResources. - : BioResources. - 1930-2126. ; 16:1, s. 1686-1701
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Tidskriftsartikel (refereegranskat)abstract
- Brewer’s spent grain (BSG) is the main solid by-product of the brewing sector. High moisture and nutrient-rich content render BSG easily perishable, leading to waste generation and environmental impacts. BSG has narrow applications in both feed and food sectors due to its composition including high fiber and low protein. Therefore, a processing strategy leading to the nutritional valorization of BSG could widen its applications. In this study, submerged cultivation of edible filamentous fungi (Aspergillus oryzae, Neurospora intermedia, and Rhizopus delemar) was introduced as a strategy to enhance the protein content of BSG. The growth of all strains in BSG increased the protein content of the fermented BSG. The highest increase of protein content (from 22.6% to 34.6%), was obtained by cultivation using A. oryzae and medium supplementation. The protein content increase was followed by a decrease in the content of polysaccharides (up to ca. 50%), namely starch, glucan, xylan, and arabinan. The addition of cellulase resulted in enhanced ethanol production from BSG but led to lower concentration of recovered solids. In conclusion, simple processing of BSG using edible filamentous fungi can lead to quality improvement of BSG, providing potential economic and environmental benefits to the brewing sector.
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| 7. |
- Parchami, Mohsen, et al.
(författare)
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MBR-Assisted VFAs production from excess sewage sludge and food waste slurry for sustainable wastewater treatment
- 2020
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Ingår i: Applied Sciences. - : MDPI AG. - 2076-3417. ; 10:8
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Tidskriftsartikel (refereegranskat)abstract
- The significant amount of excess sewage sludge (ESS) generated on a daily basis by wastewater treatment plants (WWTPs) is mainly subjected to biogas production, as for other organic waste streams such as food waste slurry (FWS). However, these organic wastes can be further valorized by production of volatile fatty acids (VFAs) that have various applications such as the application as an external carbon source for the denitrification stage at a WWTP. In this study, an immersed membrane bioreactor set-up was proposed for the stable production and in situ recovery of clarified VFAs from ESS and FWS. The VFAs yields from ESS and FWS reached 0.38 and 0.34 gVFA/gVSadded, respectively, during a three-month operation period without pH control. The average flux during the stable VFAs production phase with the ESS was 5.53 L/m2/h while 16.18 L/m2/h was attained with FWS. Moreover, minimal flux deterioration was observed even during operation at maximum suspended solids concentration of 32 g/L, implying that the membrane bioreactors could potentially guarantee the required volumetric productivities. In addition, the techno-economic assessment of retrofitting the membrane-assisted VFAs production process in an actual WWTP estimated savings of up to 140 €/h for replacing 300 kg/h of methanol with VFAs. © 2020 by the authors.
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| 8. |
- Parchami, Mohsen, et al.
(författare)
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Starch and protein recovery from brewer's spent grain using hydrothermal pretreatment and their conversion to edible filamentous fungi – A brewery biorefinery concept
- 2021
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Ingår i: Bioresource Technology. - : Elsevier. - 0960-8524 .- 1873-2976. ; 337
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Tidskriftsartikel (refereegranskat)abstract
- This study aimed at recovering a highly concentrated starch and protein stream from the brewer's spent grain (BSG). The effect of pretreatment temperature and retention time on the solubilization of starch and protein; and the generation of fermentation inhibitors were studied. Then, the application of recovered streams for fungal cultivation was evaluated using different edible fungi Aspergillus oryzae, Neurospora intermedia, and Rhizopus delemar. The hydrothermal pretreatment resulted in the highest solubilized starch concentration, 43 g/L, corresponding to 83% solubilization of initial BSG starch content. The highest protein concentration was 27 g/L (48% solubilization of initial BSG protein content). Cultivation with Neurospora intermedia on the recovered streams from the two best pretreatment conditions, 140 ℃ for 4 h and 180 ℃ for 30 min, resulted in pure fungal biomass with the highest protein content 59.62% and 50.42% w/w, respectively. Finally, a brewery biorefinery was proposed for the valorization of BSG.
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| 9. |
- Parchami, Mohsen
(författare)
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Unlocking the Potential of Brewer’s Spent Grain : Sustainable Biorefinery Approach and Value-Added Product Generation
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Brewer’s spent grain (BSG) constitutes 85% of brewing byproducts and 30% of initial malt. In 2021, BSG production reached approximately 37.2 million tons. Owing to its high moisture and nutritional content, BSG is prone to biological deterioration, causing environmental issues when discarded as waste. It has limited application as low-quality animal feed owing to its high fiber and low protein content, making landfilling the primary disposal method. However, BSG's abundance of starch, cellulose, hemicellulose, lignin, and protein make it ideal for value-added product generation in a biorefinery. The aim of this research was to investigate BSG fractionation and identify valuable products from each fraction, ultimately establishing a BSG-based biorefinery for sustainable valorization. Fungal cultivation, anaerobic digestion, hydrothermal, and organosolv pretreatments were employed to establish a BSG-based biorefinery. Edible filamentous fungi (Aspergillus oryzae, Neurospora intermedia, and Rhizopus delemar) were cultivated on crude BSG to produce food and feed-grade biomass. Fungal growth increased the protein content of the BSG by up to 47%. However, entangled solids with fungal filaments negatively affected product digestibility, limiting its incorporation in food and feed. This problem was resolved by recovering a solid-free, starch- and protein-rich stream from BSG via hydrothermal pretreatment. Hydrothermal pretreatment effectively separated BSG's starch and protein components, with solubilizations reaching 82% and 48% of the initial content, respectively. Fungal assimilation of the liquid stream produced pure, high-protein biomass and high ethanol yield. However, most of the BSG cellulose and lignin remained in the solid fraction. Organosolv pretreatment was applied to further separate BSG polymers into valorizable fractions efficiently, yielding a cellulose-rich solid stream, polysaccharide-rich organosolv liquor, and high-purity lignin (~95%). This pure lignin product can enhance the biorefinery’s economy and be sold or converted into platform chemicals. Direct fungal cultivation on cellulose-rich pulp and liquor fractions from organosolv revealed that the liquor fraction was suitable for producing pure, high-protein fungal biomass, while the pulp fraction required further processing. Moreover, anaerobic digestion was employed to produce a diverse array of products improving the product flexibility of the biorefinery. Organosolv liquor produced biohydrogen and volatile fatty acids (VFAs) without methanogen inhibition, while BSG and BSG organosolv solid fractions generated biogas. Inhibiting methanogens shifted the BSG process towards VFAs production, while organosolv solid fractions showed limited potential for VFAs generation. These results illustrate that BSG can serve as the foundation for a multi-product biorefinery that generates food-grade fungal biomass and valuable co-products, including high-purity lignin, bioethanol, biogas, biohydrogen, and VFAs. This flexibility allows the biorefinery to adapt to market changes and ensure its economic viability.
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| 10. |
- Wainaina, Steven, et al.
(författare)
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Food waste-derived volatile fatty acids platform using an immersed membrane bioreactor
- 2018
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Ingår i: Bioresource Technology. - : Elsevier BV. - 0960-8524 .- 1873-2976.
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Tidskriftsartikel (refereegranskat)abstract
- Volatile fatty acids (VFAs) are the key intermediates from anaerobic digestion (AD) process that can be a platform to synthesize products of higher value than biogas. However, some obstacles still exist that prevent large-scale production and application of VFAs, key among them being the difficulty in recovering the acids from the fermentation medium and low product yields. In this study, a novel anaerobic immersed membrane bioreactor (iMBR) with robust cleaning capabilities, which incorporated frequent backwashing to withstand the complex AD medium, was designed and applied for production and in situ recovery of VFAs. The iMBR was fed with food waste and operated without pH control, achieving a high yield of 0.54 g VFA/g VSadded. The continuous VFA recovery process was investigated for 40 days at OLRs of 2 gVS/L/d and 4 gVS/L/d without significant change in the permeate flux at a maximum suspended solids concentration of 31 g/L.
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