A critical review on biodegradable food packaging for meat: Materials, sustainability, regulations, and perspectives in the EU.

The development of biodegradable packaging is a challenge, as conventional plastics have many advantages in terms of high flexibility, transparency, low cost, strong mechanical characteristics, and high resistance to heat compared with most biodegradable plastics. The quality of biodegradable materials and the research needed for their improvement for meat packaging were critically evaluated in this study. In terms of sustainability, biodegradable packagings are more sustainable than conventional plastics; however, most of them contain unsustainable chemical additives. Cellulose showed a high potential for meat preservation due to high moisture control. Polyhydroxyalkanoates and polylactic acid (PLA) are renewable materials that have been recently introduced to the market, but their application in meat products is still limited. To be classified as an edible film, the mechanical properties and acceptable control over gas and moisture exchange need to be improved. PLA and cellulose-based films possess the advantage of protection against oxygen and water permeation; however, the addition of functional substances plays an important role in their effects on the foods. Furthermore, the use of packaging materials is increasing due to consumer demand for natural high-quality food packaging that serves functions such as extended shelf-life and contamination protection. To support the importance moving toward biodegradable packaging for meat, this review presented novel perspectives regarding ecological impacts, commercial status, and consumer perspectives. Those aspects are then evaluated with the specific consideration of regulations and perspective in the European Union (EU) for employing renewable and ecological meat packaging materials. This review also helps to highlight the situation regarding biodegradable food packaging for meat in the EU specifically.

Positive role of non-catalytic proteins on mitigating inhibitory effects of lignin and enhancing cellulase activity in enzymatic hydrolysis: Application, mechanism, and prospective.

Fermentable sugar production from lignocellulosic biomass has received considerable attention and has been dramatic progress recently. However, due to low enzymatic hydrolysis (EH) yields and rates, a high dosage of the costly enzyme is required, which is a bottleneck for commercial applications. Over the last decades, various strategies have been developed to reduce cellulase enzyme costs. The progress of the non-catalytic additive proteins in mitigating inhibition in EH is discussed in detail in this review. The low efficiency of EH is mostly due to soluble lignin compounds, insoluble lignin, and harsh thermal and mechanical conditions of the EH process. Adding non-catalytic proteins into the EH is considered a simple and efficient approach to boost hydrolysis yield. This review discussed the multiple mechanical steps involved in the EH process. The effect of physicochemical properties of modified lignin on EH and its interaction with cellulase and cellulose are identified and discussed, which include hydrogen bonding, hydrophobic, electrostatic, and cation-π interactions, as well as physical barriers. Moreover, the effects of different conditions of EH that lead to cellulase deactivation by thermal and mechanical mechanisms are also explained. Finally, recent advances in the development, potential mechanisms, and economic feasibility of non-catalytic proteins on EH are evaluated and perspectives are presented.

Valorization of vinasse and whey to protein and biogas through an environmental fungi-based biorefinery.

Vinasse and whey are wastewaters that are produced in large quantities in the sugar-to-ethanol and dairy industries, respectively. They pose a considerable threat to the environment due to the high concentration of nutrients and COD. In this study, the potential of producing protein-rich fungal biomass and biomethane from vinasse and whey through a two-stage biorefinery was examined. In the first stage, an edible and safe for human filamentous fungus, Neurospora intermedia, was cultivated on these wastewaters. To maximize the fungal biomass yield, the cultivation parameters, i.e., pH, vinasse to whey ratio, incubation time, and nutrients supplementation, were optimized. The highest yield of 12.0 g biomass per L of wastewaters was obtained by cultivation at pH 6.5 and vinasse to whey ratio of 25:75 (v/v) for 96 h with nitrogen source supplementation. The N. intermedia biomass contained about 45% protein and noticeable essential amino acid contents, comparable to commercial sources of protein for aquatic feed such as soybean meal and fishmeal. In the second stage, the effluent of fungal cultivation was anaerobically digested to produce 425 mL/g VS biomethane. Overall, 1 m3 of wastewater yielded 5.4 kg crude protein and 10.3 m3 methane, accompanied by 93.3% COD removal.

Exergy analysis of a whole-crop safflower biorefinery: A step towards reducing agricultural wastes in a sustainable manner.

The huge amount of agro-wastes generated due to expanding agricultural activities can potentially cause serious environmental and human health problems. Using the biorefinery concept, all parts of agricultural plants can be converted into multiple value-added bioproducts while reducing waste generation. This approach can be viewed as an effective strategy in developing and realizing a circular bioeconomy by accomplishing the dual goals of waste mitigation and energy recovery. However, the sustainability issue of biorefineries should still be thoroughly scrutinized using comprehensive resource accounting methods such as exergy-based approaches. In light of that, this study aims to conduct a detailed exergy analysis of whole-crop safflower biorefinery consisting of six units, i.e., straw handling, biomass pretreatment, bioethanol production, wastewater treatment, oil extraction, and biodiesel production. The analysis is carried out to find the major exergy sink in the developed biorefinery and discover the bottlenecks for further performance improvements. Overall, the wastewater treatment unit exhibits to be the major exergy sink, amounting to over 70% of the total thermodynamic irreversibility of the process. The biomass pretreatment and bioethanol production units account for 12.4 and 10.3% of the total thermodynamic inefficiencies of the process, respectively. The exergy rates associated with bioethanol, biodiesel, lignin, biogas, liquid digestate, seed cake, sodium sulfate, and glycerol are determined to be 5918.5, 16516.8, 10778.9, 1741.4, 6271.5, 15755.8, 3.4, and 823.5 kW, respectively. The overall exergetic efficiency of the system stands at 72.7%, demonstrating the adequacy of the developed biorefinery from the thermodynamic perspective.

Mucoralean fungi for sustainable production of bioethanol and biologically active molecules.

Mucoralean fungi are suitable microorganisms for the sustainable production of food, fodder, and fuels from inexpensive natural resources. Ethanol-producing Mucorales are particularly advantageous for second-generation ethanol production in comparison to the conventional ethanolic yeasts and bacteria. They are able to ferment a wide range of sugars to a range of valuable products, while they are typically resistance against the inhibitors available in different substrates, including untreated lignocellulosic hydrolysates. In addition to a high ethanol yield, the fungi produce several commercially valuable by-products, including chitosan, microbial oil (mainly polyunsaturated fatty acids), and protein. Moreover, the fungal extracts can replace the expensive nutrients required in fermentation. Besides, their morphologies can be altered from filamentous to yeast like and are adjustable based on the process requirement. The focus of this review is on applying Mucorales in producing ethanol and the biomass by-products thereof.

Bioenergy production from sweet sorghum stalks via a biorefinery perspective.

Besides free sugars, sweet sorghum stalks contain cellulose and hemicellulose that can be used for biofuel production. The pretreatment of stalks without the extraction of free sugars is more complicated than typical lignocelluloses, because of the degradation of free sugars during most pretreatment processes. In this study, the bioconversion of sweet sorghum stalks into biogas and bioethanol was studied using an improved organosolv pretreatment within a biorefinery framework. The organosolv pretreatment was developed using an aqueous solution of ethanol (EtOH) and isopropanol (IPOH). The process was optimized to obtain a liquor containing free sugars with the least sugar degradations together with a highly degradable solid fraction. The liquor was subjected to anaerobic digestion for biomethane production, while the solid was used for ethanol production via simultaneous saccharification and fermentation (SSF). The most influencing pretreatment parameters, i.e., temperature, time, alcohol to water ratio, EtOH to IPOH ratio, and the presence or absence of sulfuric acid (as a catalyst), were adjusted to achieve the highest yields of bioconversion. The maximum methane and ethanol production yields of 271.2 mL CH4/g VS and 87.8% (equal to the gasoline equivalent of 0.170 and 0.241 L/kg, respectively) were achieved from the liquor and pretreated solid, respectively; however, they were obtained at different optimum conditions. Considering the biorefinery perspective, the highest gasoline equivalent of 0.249 L/kg was efficiently obtained from the whole process after pretreatment at 140 °C for 30 min using 60:20 EtOH/IPOH ratio in the presence of 1% sulfuric acid. Further analyses, including enzymatic adsorption/desorption, compositional analysis, FTIR, and SEM, were conducted to investigate the effects of this newly developed pretreatment on the substrate.

Structural features influential to enzymatic hydrolysis of cellulose-solvent-based pretreated pinewood and elmwood for ethanol production.

Dissolution of lignocelluloses in N-methylmorpholine-N-oxide (NMMO or NMO) at moderate conditions, e.g., 120 °C for 3 h under atmospheric pressure, and regeneration with water, is among the most effective nonderivatization pretreatment for the improvement of enzymatic hydrolysis and ethanol production. The effects of the pretreatment on two different types of wood, hardwood elm and softwood pine, were compared via physicochemical structural analyses, i.e., FTIR, XRD, SEM, TGA, and enzyme adsorption techniques, to relate their properties to the extent of enzymatic conversion. After the pretreatment, cellulose was highly recovered and characterized to be mainly cellulose II and amorphous cellulose, with lower cellulose crystallinity index, higher thermal stability, and more favorable surface features for hydrolysis, compared to native woods. Moreover, the strength of enzyme binding onto the lignocelluloses, which was directly related to the enzymatic hydrolysis rate, increased by 57% and 164% for pinewood and elmwood, respectively. The highest total reducing sugars yield for untreated pinewood was 9.8% (74 mg/g-substrate) and improved to 58.5% (330 mg/g-substrate) after the pretreatment, whereas the corresponding values for elmwood were 14.7% (104 mg/g-substrate) vs. 51.4% (274 mg/g-substrate). Furthermore, maximum ethanol theoretical yields of 63.5 and 41.4% were obtained from pinewood and elmwood by Saccharomyces cerevisiae and Mucor indicus, respectively.

Improvement of ethanol and biogas production from sugarcane bagasse using sodium alkaline pretreatments.

Sugarcane bagasse was pretreated with sodium carbonate, sodium sulfite, and sodium acetate in concentrations of 0.5 M and 0.25 M, as well as hydrothermal pretreatment, to break down its structural recalcitrance and improve biogas and ethanol production. The pretreatments were conducted at 100, 140, and 180 °C for 1 h. The highest biogas and ethanol production was observed for sugarcane bagasse pretreated with 0.5 M sodium carbonate solution at 140 °C, which was 239 ±â€¯20 Nml CH4/g VS, and 7.27 ±â€¯0.70 g/l, respectively, containing gasoline equivalents of 164.2 ±â€¯14.3 l/ton of raw bagasse and 147.8 ±â€¯14.2 l/ton of raw bagasse, respectively. The highest gasoline equivalent was obtained for biogas production from the substrate pretreated with 0.5 M sodium sulfite solution at 100 °C (190.2 ±â€¯2.1 l/ton of raw bagasse). In comparison to sodium carbonate and sodium sulfite, sodium acetate had less effect on biofuel production and was comparable with hydrothermal pretreatment. In contradiction to sodium acetate pretreated bagasse, in which increased pretreatment temperature intensified biofuel production, a reduction of biofuel production was observed for sodium carbonate and sodium sulfite pretreatment when temperature was increased from 140 to 180 °C. Besides considerable amounts of biofuel production at the best conditions obtained, over 762 and 543 kilotons of equivalent CO2 can be reduced annually in Iran by biogas and ethanol production from sugarcane, respectively.

Impact of Phosphate, Potassium, Yeast Extract, and Trace Metals on Chitosan and Metabolite Production by Mucor indicus.

In this study the effects of phosphate, potassium, yeast extract, and trace metals on the growth of Mucor indicus and chitosan, chitin, and metabolite production by the fungus were investigated. Maximum yield of chitosan (0.32 g/g cell wall) was obtained in a phosphate-free medium. Reversely, cell growth and ethanol formation by the fungus were positively affected in the presence of phosphate. In a phosphate-free medium, the highest chitosan content (0.42 g/g cell wall) and cell growth (0.66 g/g sugar) were obtained at 2.5 g/L of KOH. Potassium concentration had no significant effect on ethanol and glycerol yields. The presence of trace metals significantly increased the chitosan yield at an optimal phosphate and potassium concentration (0.50 g/g cell wall). By contrast, production of ethanol by the fungus was negatively affected (0.33 g/g sugars). A remarkable increase in chitin and decrease in chitosan were observed in the absence of yeast extract and concentrations lower than 2 g/L. The maximum chitosan yield of 51% cell wall was obtained at 5 g/L of yeast extract when the medium contained no phosphate, 2.5 g/L KOH, and 1 mL/L trace metal solution.

Co-Production of Fungal Biomass Derived Constituents and Ethanol from Citrus Wastes Free Sugars without Auxiliary Nutrients in Airlift Bioreactor.

The potential of two zygomycetes fungi, Mucor indicus and Rhizopus oryzae, in assimilating citrus waste free sugars (CWFS) and producing fungal chitosan, oil, and protein as well as ethanol was investigated. Extraction of free sugars from citrus waste can reduce its environmental impact by decreasing the possibility of wild microorganisms growth and formation of bad odors, a typical problem facing the citrus industries. A total sugar concentration of 25.1 g/L was obtained by water extraction of citrus waste at room temperature, used for fungal cultivation in shake flasks and airlift bioreactor with no additional nutrients. In shake flasks cultivations, the fungi were only able to assimilate glucose, while fructose remained almost intact. In contrast, the cultivation of M. indicus and R. oryzae in the four-liter airlift bioreactor resulted in the consumption of almost all sugars and production of 250 and 280 g fungal biomass per kg of consumed sugar, respectively. These biomasses correspondingly contained 40% and 51% protein and 9.8% and 4.4% oil. Furthermore, the fungal cell walls, obtained after removing the alkali soluble fraction of the fungi, contained 0.61 and 0.69 g chitin and chitosan per g of cell wall for M. indicus and R. oryzae, respectively. Moreover, the maximum ethanol yield of 36% and 18% was obtained from M. indicus and R. oryzae, respectively. Furthermore, that M. indicus grew as clump mycelia in the airlift bioreactor, while R. oryzae formed spherical suspended pellets, is a promising feature towards industrialization of the process.

Improvement of acetone, butanol, and ethanol production from woody biomass using organosolv pretreatment.

A suitable pretreatment is a prerequisite of efficient acetone-butanol-ethanol (ABE) production from wood by Clostridia. In this study, organosolv fractionation, an effective pretreatment with ability to separate lignin as a co-product, was evaluated for ABE production from softwood pine and hardwood elm. ABE production from untreated woods was limited to the yield of 81 g ABE/kg wood and concentration of 5.5 g ABE/L. Thus, the woods were pretreated with aqueous ethanol at elevated temperatures before hydrolysis and fermentation to ABE by Clostridium acetobutylicum. Hydrolysis of pine and elm pretreated at 180 °C for 60 min resulted in the highest sugar concentrations of 16.8 and 23.2 g/L, respectively. The hydrolysate obtained from elm was fermented to ABE with the highest yield of 121.1 g/kg and concentration of 11.6 g/L. The maximum yield of 87.9 g/kg was obtained from pine pretreated for 30 min at 150 °C. Moreover, structural modifications in the woods were investigated and related to the improvements. The woody biomasses are suitable feedstocks for ABE production after the organosolv pretreatment. Effects of the pretreatment conditions on ABE production might be related to the reduced cellulose crystallinity, reduced lignin and hemicellulose content, and lower total phenolic compounds in the hydrolysates.

Effects of Plant Growth Hormones on Mucor indicus Growth and Chitosan and Ethanol Production.

The objective of this study was to investigate the effects of indole-3-acetic acid (IAA) and kinetin (KIN) on Mucor indicus growth, cell wall composition, and ethanol production. A semi-synthetic medium, supplemented with 0-5 mg/L hormones, was used for the cultivations (at 32 °C for 48 h). By addition of 1 mg/L of each hormone, the biomass and ethanol yields were increased and decreased, respectively. At higher levels, however, an inverse trend was observed. The glucosamine fraction of the cell wall, as a representative for chitosan, followed similar but sharper changes, compared to the biomass. The highest level was 221% higher than that obtained without hormones. The sum of glucosamine and N-acetyl glucosamine (chitin and chitosan) was noticeably enhanced in the presence of the hormones. Increase of chitosan was accompanied by a decrease in the phosphate content, with the lowest phosphate (0.01 g/g cell wall) being obtained when the chitosan was at the maximum (0.45 g/g cell wall). In conclusion, IAA and KIN significantly enhanced the M. indicus growth and chitosan production, while at the same time decreasing the ethanol yield to some extent. This study shows that plant growth hormones have a high potential for the improvement of fungal chitosan production by M. indicus.

Environmental impact assessment of a novel third-generation biorefinery approach for astaxanthin and biofuel production.

A novel third-generation biorefinery approach, including two paths of Ethanol/methane production pathway (EMP) and the direct methane production pathway (DMP), for astaxanthin and ethanol and biogas production from the freshwater microalgae Haematococcus pluvialis was developed previously. To ensure its environmental sustainability, a comprehensive life cycle assessment (LCA) study was conducted based on 1-GJ energy generation from biomethane as the functional unit. Results indicate that the EMP pathway had higher environmental impacts on all categories due to more stages and chemicals/energy consumption (at least five times greater effect). Results showed that while the enzymatic hydrolysis step followed by the fermentation stage was the main contributor to all environmental categories in the EMP route, astaxanthin induction dominated all environmental categories in the DMP route. The results showed that sodium nitrate, phosphate salts, inoculum sludge, acetone, and electricity had considerable environmental impacts. Moreover, despite low enzyme usage in enzymatic hydrolysis, these proteins significantly impacted all environmental categories in this stage. The baseline analysis concluded that to produce 1 GJ energy from methane, about 88 kg and 13 kg CO2 were generated from the EMP and DMP pathways, respectively. A sensitivity analysis was also conducted to compare various ratios of chemicals, such as phosphate salts, with high contributions to enzymatic hydrolysis and astaxanthin induction stages in the EMP and DMP routes, respectively. Finally, the LCA results revealed that the DMP pathway is more environmentally friendly with the same economic value of biomethane and astaxanthin production. This LCA study updated the data related to the environmental assessment of processes to utilize H. pluvialis to produce biofuels and astaxanthin simultaneously.

Life cycle analysis of apple pomace biorefining for biofuel and pectin production.

This study investigated the environmental impacts associated with converting apple pomace, a globally abundant resource, into biofuels and high-value products using a comparative consequential life cycle assessment. In three developed scenarios, an acid pretreatment method was applied and the pretreated liquid was used for ethanol and pectin production. The pretreated solids were utilized to produce different products: scenario 1 produced biogas, scenario 2 generated butanol, and scenario 3 yielded both biogas and butanol from the solids. The results demonstrated that scenario 1 exhibited the best performance compared to the other two scenarios, imposing the lowest environmental burdens across all damage categories, including human health, ecosystems, and resources. Despite the induced impacts, the benefits of avoided products, i.e., ethanol, natural gas, butanol, acetone, and pectin, compensated for these induced environmental impacts to some extent. The results also revealed that among all products generated through the biorefineries, first-generation ethanol substitution had the most significant positive environmental impacts. Overall, the biorefinery developed in scenario 1 represents the most feasible strategy for a circular bioeconomy. It performs 84.38 % and 72.98 % better than scenarios 2 and 3 in terms of human health, 85.34 % and 74.54 % better in terms of ecosystems, and more than 100 % better in terms of resources. Conversely, scenario 2 resulted in the highest net impacts across all damage categories. Furthermore, in scenario 1, the midpoint results showed 83.10 % and 71.08 % lower impacts on global warming, 85.15 % and 74.17 % lower impacts on terrestrial acidification, and 99.26 % and 98.53 % lower impacts on fossil resource scarcity compared to scenarios 2 and 3, respectively. In conclusion, the first scenario shows promise for the sustainable valorization of apple pomace.

Starch biocomposites preparation by incorporating organosolv lignins from potato crop residues.

Plastic wastes accumulated due to food packaging pose environmental threats. This study proposes biopolymeric films containing lignins extracted from potato crop residues (PCR) through organosolv treatment as a green alternative to non-degradable food packaging. The isolation process yielded 43.9 wt% lignins with a recovery rate of 73.5 wt% achieved under optimum conditions at 180 °C with 50 % v/v ethanol. The extracted lignins were then incorporated into a starch matrix to create biocomposite films. ATR-FTIR analysis confirmed interactions between the starch matrix and extracted lignins, and XRD analysis showed the amorphous structure of lignins, reducing film crystallinity. The addition of 1 wt% of extracted lignins resulted in a 87 % reduction in oxygen permeability, a 25 % increase in the thermal stability of the film, and a 78 % enhancement in antioxidant. Furthermore, introducing 3 wt% lignins led to the lowest water vapor transmission rate, measuring 9.3 × 10-7 kg/s·m2. Morphological studies of the films demonstrated a homogeneous and continuous structure on both the surface and cross-sectional areas when the lignins content was below 7 wt%. These findings highlight the potential of using organosolv lignins derived from potato crop residues as a promising additive for developing eco-friendly films designed for sustainable food packaging.

Improvement of hydrolysis and fermentation of sugarcane bagasse by soaking in aqueous ammonia and methanolic ammonia.

Sugarcane bagasse was pretreated by soaking it in aqueous ammonia (SAA) and methanolic aqueous ammonia (SMAA) at 70 °C for 12 h. Then the pretreated as well as untreated bagasse was subjected to enzymatic hydrolysis at 50 °C for 72 h by 15 FPU cellulase and 30 CBU cellobiase per g of substrate. The hydrolysis of SAA-pretreated bagasse with a solid to liquid (S:L) ratio of 1:10 resulted in 95.9% of the maximum theoretical yield. The production yield for SMAA at an S:L ratio of 1:6 with 15% methanol was 88.6%, while it was only 21.3% for the untreated bagasse. Ethanol production by simultaneous saccharification and fermentation was conducted at 37 °C for 72 h. The results revealed that the ethanol production yield was improved from 12.7% for the untreated bagasse to 92.45% and 90.8% for the SAA and the SMAA pretreated bagasse, respectively. The compositional and chemical structural analysis suggested that lignin removal and crystallinity reduction were responsible for the hydrolysis and SSF improvements.

Dry chemical processing and ensiling of rice straw to improve its quality for use as ruminant feed.

In this study, changes in the chemical composition, pH, cell wall and degradability of ensiled rice straw were investigated when treated with alkali, acid, oxidant agents (1-11 %, w/w) and a combination of an oxidant with either an alkali (ALHP) or an acid (ACHP). The findings of the study revealed that ALHP had a lower efficiency in enhancing fibre degradability compared to alkali alone. Oxidant treatment showed no detectable changes in pH, dry matter (DM) and phenolic compound (PC) solubility, or in silica and fibre content, but led to increased esterified groups formed within the cell wall constituents (hemicellulose and lignin). Increasing acid concentration led to an exponential change in both pH and solubility of DM and hemicelluloses while it quadratically increased PC and silica solubility. Moreover, crystallinity, hydrogen bonding and esterification were enhanced under high acid concentrations (11 %), but decreased under mild acid conditions (5 %). Increased alkalinity led to the linear enhancement of DM and PC solubility. Solubility of silica and hemicellulose did not exhibit any significant changes with alkali concentration above 7 %. A gradual enhancement (29 %) was observed in ruminal DM degradability with increasing oxidant concentration, whereas exponential (91 %) and quadratic (23 %) enhancements were observed with alkaline and acid treatments, respectively. Treatment with acid showed observable reductions in the degradability of both cellulose and hemicellulose, whereas oxidant treatment reduced only that of hemicellulose. Treatment with 7 % alkali (pH ∼ 12) followed by ensiling appeared to be a promising process for improving rice straw quality.

A critical review on pretreatment and detoxification techniques required for biofuel production from the organic fraction of municipal solid waste.

The organic fraction of municipal solid waste (OFMSW) is a widely-available promising feedstock for biofuel production. However, the presence of different inhibitors originating from fruit and food/beverage wastes as well as recalcitrant lignocellulosic fractions hampers its bioconversion. This necessitates a pretreatment to augment the biodigestibility and fermentability of OFMSW. Hence, this review aims to provide the in-vogue inhibitory compound removal and pretreatment techniques that have been employed for efficient OFMSW conversion into biofuels, i.e., hydrogen, biogas, ethanol, and butanol. The techniques are compared concerning their mode of action, chemical and energy consumption, inhibitor formation and removal, economic feasibility, and environmental sustainability. This critique also reviews the existing knowledge gap and future perspectives for efficient OFMSW valorization. The insights provided pave the way toward developing energy-resilient cities while addressing environmental crises related to generating OFMSW.

Sustainable lignocellulose fractionation by integrating p-toluenesulfonic acid/pentanol pretreatment with mannitol for efficient production of glucose, native-like lignin, and furfural.

A new cutting-edge lignocellulose fractionation technology for the co-production of glucose, native-like lignin, and furfural was introduced using mannitol (MT)-assisted p-toluenesulfonic acid/pentanol pretreatment, as an eco-friendly process. The addition of optimized 5% MT in pretreatment enhanced the delignification rate by 29% and enlarged the surface area and biomass porosity by 1.07-1.80 folds. This increased the glucose yield by 45% (from 65.34 to 94.54%) after enzymatic hydrolysis relative to those without MT. The extracted lignin in the organic phase of pretreatment exhibited ß-O-4 bonds (61.54/100 Ar) properties of native cellulosic enzyme lignin. Lignin characterization and molecular docking analyses revealed that the hydroxyl tails of MT were incorporated with lignin and formed etherified lignin, which preserved high lignin integrity. The solubilized hemicellulose (96%) in the liquid phase of pretreatment was converted into furfural with a yield of 83.99%. The MT-assisted pretreatment could contribute to a waste-free biorefinery pathway toward a circular bioeconomy.

Production of chemicals and utilities in-house improves the environmental sustainability of phytoplankton-based biorefinery.

Life cycle assessment was used to evaluate the environmental impacts of phytoplanktonic biofuels as possible sustainable alternatives to fossil fuels. Three scenarios were examined for converting planktonic biomass into higher-value commodities and energy streams using the alga Scenedesmus sp. and the cyanobacterium Arthrospira sp. as the species of interest. The first scenario (Sc-1) involved the production of biodiesel and glycerol from the planktonic biomass. In the second scenario (Sc-2), biodiesel and glycerol were generated from the planktonic biomass, and biogas was produced from the residual biomass. The process also involved using a catalyst derived from snail shells for biodiesel production. The third scenario (Sc-3) was similar to Sc-2 but converted CO2 from the biogas upgrading to methanol, which was then used in synthesizing biodiesel. The results indicated that Sc-2 and Sc-3 had a reduced potential (up to 60 % less) for damaging human health compared to Sc-1. Sc-2 and Sc-3 had up to 61 % less environmental impact than Sc-1. Sc-2 and Sc-3 reduced the total cumulative exergy demand by up to 44 % compared to Sc-1. In conclusion, producing chemicals and utilities within the biorefinery could significantly improve environmental sustainability, reduce waste, and diversify revenue streams.