Biomass, Volume 4, Issue 1 (March 2024) – 10 articles

Each year, a substantial amount of food is discarded around the globe. A significant portion of this waste consists of by-products derived from Citrus fruits such as lemons. The purpose of this research is to examine the polyphenol extraction and the antioxidant ability of lemon peel using cloud point extraction (CPE), a sustainable approach. CPE was conducted using three steps with a 20% w/v concentration of Span 20 as the surfactant, which has a critical micellar concentration of 6.13 × 10⁻⁵ mol/L. The pH was set at 7 and a salt concentration of 20% was maintained at 45 °C for 20 min. The subsequent outcomes of the analysis were obtained: total polyphenol content (TPC): 526.32 mg gallic acid equivalents per liter; total flavonoid content (TFC): 90.22 mg rutin equivalents per liter; FRAP, DPPH, and hydrogen peroxide assays: 2.40, 2.68 and 1.03 mmol ascorbic acid equivalents per liter, respectively, and 168.63 mg/L ascorbic acid content. The quantification of the polyphenolic compounds through High-Performance Liquid Chromatography showed that the most abundant compounds in the lemon peels are eriocitrin (159.43 mg/L) and hesperidin (135.21 mg/L). The results indicate that the proposed CPE technique is successful in extracting antioxidant compounds from lemon peels. The generated extracts have the potential to be exploited as dietary additives to enhance human health and can also be utilized for nutraceuticals or pharmaceutical purposes. Full article

The hunt for renewable and alternative fuels has driven research towards the biological conversion of lignocellulosic biomass (LCB) into biofuels, including bioethanol and biohydrogen. Among the natural biomass utilization systems (NBUS), termites represent a unique and easy-to-access model system to study host–microbe interactions towards lignocellulose bioconversion/valorization. Termites have gained significant interest due to their highly efficient lignocellulolytic systems. The wood-feeding termites apply a unique and stepwise process for the hydrolysis of lignin, hemicellulose, and cellulose via biocatalytic processes; therefore, mimicking their digestive metabolism and physiochemical gut environments might lay the foundation for an innovative design of nature-inspired biotechnology. This review highlights the gut system of termites, particularly the wood-feeding species, as a unique model for future biorefinery. The gut system of termites is a treasure-trove for prospecting novel microbial species, including protists, bacteria, and fungi, having higher biocatalytic efficiencies and biotechnological potentials. The significance of potential bacteria and fungi for harnessing the enzymes appropriate for lignocellulosic biorefinery is also discussed. Termite digestomes are rich sources of lignocellulases and related enzymes that could be utilized in various industrial processes and biomass-related applications. Consideration of the host and symbiont as a single functioning unit will be one of the most crucial strategies to expedite developments in termite-modeled biotechnology in the future. Full article

Industrial hemp is a versatile crop, and its products have important applications in the food, cosmetic, pharmaceutical, textile, paper and composite industries. Since its legalization in the U.S. in 2018, interest in growing and using hemp has been increasing. This study evaluated the techno-economics of hemp grain and fiber production, harvest and post-harvest logistics, the drying and storage of hemp grain, and the decortication of fiber stalks. The analysis was performed using a process modeling approach with data obtained from the literature considering a farm size of 162 ha (average U.S. farm size). The input parameters were used as distributed functions and the results obtained are reported as interquartile ranges after 10,000 Monte Carlo simulations. The total cost of producing and processing hemp grain and fiber was estimated to be in the interquartile range of USD 2911–3566 Mg⁻¹ and USD 1155–1505 Mg⁻¹, respectively. The costs of seed and fertilizer along with grain and fiber yields were found to be the major factors influencing field production costs, while costs associated with facilities and labor were the main costs in fiber processing. Despite the high resource requirements and processing costs, high-value applications of hemp grain and fiber show great potential to produce net incomes of USD 426–3701 Mg⁻¹ and USD 1570–2016 Mg⁻¹, respectively. Full article

Fermentation is an oxygen-free biological process that produces hydrogen, a clean, renewable energy source with the potential to power a low-carbon economy. Bibliometric analysis is crucial in academic research to evaluate scientific production, identify trends and contributors, and map the development of a field, providing valuable information to guide researchers and promote scientific innovation. This review provides an advanced bibliometric analysis and a future perspective on fermentation for hydrogen production. By searching WoS, we evaluated and refined 62,087 articles to 4493 articles. This allowed us to identify the most important journals, countries, institutions, and authors in the field. In addition, the ten most cited articles and the dominant research areas were identified. A keyword analysis revealed five research clusters that illustrate where research is progressing. The outlook indicates that a deeper understanding of microbiology and support from energy policy will drive the development of hydrogen from fermentation. Full article

Few valorization pathways have been implemented as alternatives to reduce the orange peel waste (OPW) disposal in landfills. OPW can be a source of income or economic savings in juice production factories since this waste is a potential source of value-added products (e.g., bioactive compounds) and energy vectors (e.g., biogas). Valorization alternatives should be based on (i) orange peel chemical composition, (ii) market analysis, and (iii) availability. Nevertheless, few literature papers have highlighted the chemical composition change caused by the different juice production schemes as a potential opportunity to obtain different value-added products and biorefinery schemes. Thus, the aims of this review paper are related to (i) reviewing different orange fruit processing pathways, (ii) analyzing several OPW chemical compositions reported in the open literature, (iii) providing a summary of OPW extraction pathways for bioactive compounds production, and (iv) evaluating the effect of applying different extraction methods on bioactive compound extraction performance. This review includes a description of the OPW matrix, market insights, packaging, physicochemical characterization, processing technologies, and suggested biorefinery approaches. Finally, different extraction methods for obtaining bioactive compounds from OPW are compared. As a result, the supercritical fluid extraction process has the highest extraction performance and selectivity since this method extracted a high amount of hesperidin (8.18 g/kg OPW db.). In conclusion, OPW is a source of bioactive compounds and valuable products that can be introduced in juice-producing factories to increase product portfolio or economic savings by changing the energy matrix. Full article

The industrial processing of coconut to produce valuable foods, such as water and milk, generates large volumes of waste, especially the fruit shell. Despite this, material can be used in bioprocess applications, e.g., the production of enzymes, its recalcitrance hinders the cultivation of microorganisms, and low productivity is usually achieved. In this study, the production of cellulolytic enzymes through solid-state fermentation (SSF) and their extraction was investigated using the green coconut fiber pretreated by steam explosion, followed by alkali. The fungus Trichoderma reesei CCT-2768 was cultivated, using an experimental design, to study the effect of the water activity and the amount of biomass in the reactor. The combination of the pretreatment strategies yielded more porous biomass, with less hemicellulose (5.38%, compared to 10.15% of the raw biomass) and more cellulose (47.77% and 33.96% in the pretreated and raw biomasses, respectively). The water activity significantly affected the production of cellulases, with maximum activity yielded at the highest investigated value (0.995). Lastly, the extraction of the enzymes from the cultivation medium was studied, and a 9 g/L NaCl solution recovered the highest CMCase and FPase activities (5.19 and 1.19 U/g, respectively). This study provides an important contribution to the valorization of the coconut residue through (i) the application of the steam explosion technology to optimize the production of cellulases using the SSF technology and (ii) their extraction using different solvents. Full article

The global surge in environmental pollution, largely attributed to industrialization, has fueled a pressing need for sustainable solutions. In response, the construction sector is increasingly focusing on bio-based materials such as hemp, recognized for its low environmental footprint and prominent carbon-negative quality. As designers, housebuilders, and an environmentally conscious society pivot towards ecological alternatives to standard building materials, hempcrete emerges as a promising candidate. As a composite material mainly made from hemp hurd/shiv, water, and lime, hempcrete offers the ability to sequester carbon long after its incorporation into structures. As a result, the hemp cultivation process—which can be completed within less than four months—ensures that more carbon is absorbed during production and deployment than emitted, e.g., per one study, sequestration on the order of 300 kg of CO₂ per m³ of hempcrete. In comparison to concrete, hempcrete offers a more sustainable footprint, given its recyclability post life cycle. This state-of-the-art review paper delves deep into different aspects of hempcrete, summarizing its multifaceted attributes, particularly its compressive strength. Based on the study conducted, the paper also suggests strategies to augment this strength, thereby transitioning hempcrete from a non-load-bearing material to one capable of shouldering significant weight. As architects and designers consistently strive to align their projects with high ecological standards, focusing not just on aesthetic appeal but also environmental compatibility, hempcrete becomes an increasingly fitting solution for the future of construction. Full article

Prunus avium L. and Prunus spinosa L. are valuable fruit-bearing trees known for their bioactive compounds and medicinal properties. However, limited research exists regarding their kernel oils. This study aimed to compare the chemical composition, quality parameters, and bioactive potential of the kernel oils extracted from Prunus avium L. and Prunus spinosa L. The kernel oils’ fatty acid and tocopherol profiles were characterized, and the presence of bioactive compounds were identified and quantified. Total polyphenol content (TPC) and antioxidant activity (AAC) were also measured, indicating the presence of bioactive compounds in both oils. Additionally, the main quality parameters, including oxidative status, were evaluated. The fatty acid analysis revealed a higher proportion of polyunsaturated fatty acids compared to monounsaturated fatty acids in both kernel oil samples. Linoleic acid (57–64%) and oleic acid (18–29%) were the major fatty acids in both Prunus avium L. and Prunus spinosa L. kernel oils. α-Eleostearic acid (11.87%) was quantified only in Prunus avium kernel oil. Furthermore, the α-, β-, γ-, and δ-tocopherol content were determined, and it was found that both kernel oils contained γ-tocopherol as the major tocopherol (~204–237 mg/Kg). TPC in Prunus avium L. kernel oil was measured at 9.5 mg gallic acid equivalents (GAE)/Kg and recorded as ~316% higher TPC than Prunus spinosa L. kernel oil. However, the recorded AAC were 11.87 and 14.22 μmol Trolox equivalent (TE)/Kg oil, respectively. Both oils recorded low peroxide values (~1.50 mmol H₂O₂/Kg), and low TBARS value (~0.4 mmol malondialdehyde equivalents, MDAE/Kg oil), but high p-anisidine value (23–32). The results indicated that both Prunus avium L. and Prunus spinosa L. kernel oils exhibited unique chemical compositions. Full article

In a circular economy, significant emphasis is given to the energetic valorization of agricultural byproducts. Cotton stalks are suitable as a feedstock for the production of bioenergy due to their high energy content. This study’s main focal areas are the economic viability and environmental implications of a system that can gasify or pyrolyze 25,500 tons of cotton stalk annually. To learn more about how gasification and pyrolysis affect the environment, a life cycle assessment (LCA) was conducted. This analysis evaluates the whole value chain and covers all stages of the cotton supply chain from cradle to gate, including production, harvest, transportation, and utilization. According to the findings, both systems exhibit economic viability, generating sizable profits and having quick payback times. However, despite its larger initial expenditure of EUR 2.74 million, the pyrolysis unit ends up being the better option because it has a payback period of 1.58 years, a return on investment (ROI) of 58% and a net present value (NPV) of EUR 21.5 million. Gasification is still an economically attractive alternative with a lower initial investment (EUR 1.81 million), despite having a lower ROI (36%) and NPV (EUR 10.52 million), as well as a longer payback period (2.41 years). However, the environmental implications of the gasification option are generally higher than those of pyrolysis. The impacts of gasification on fossil depletion (FDP) were estimated to be 5.7 million kg oil eq., compared to 5.3 million kg oil eq. for pyrolysis. Similarly, gasification resulted in 41.55 million kg U235 eq. and pyrolysis in 41.5 million kg U235 eq. related to impacts on ionizing radiation (IRP_HE). Other impact categories that emerge as the most important are freshwater eutrophication (FEP) and marine eutrophication (MEP). Full article

Large quantities of wine lees are produced annually by the wine industry. The high phenolic content makes them unsuitable for disposal in the environment or animal feed without a suitable treatment. In this study, wine lees were treated by Pleurotus ostreatus in submerged cultivation, producing a high-value biomass and elevated levels of laccase, an important industrial enzyme. Biomass and laccase production reached 21 g/L and 74,000 Units/L, respectively, at the optimal conditions of initial pH 6.0, 20% v/v wine lees, 30 g/L glucose, and 20 g/L yeast extract, while decolorization and dephenolization rates of the waste were over 90%. The mycelial biomass was rich in proteins and essential amino acids reaching up to 43% and 16% per dry weight, respectively. Carbohydrates and lipids were the second richest bioactive compound in biomass, with values of 29.4 ± 2.7% and 29.5 ± 2.7%, respectively. The crude laccase in the culture supernatant was purified via a simple two-step purification procedure by 4.4-fold with a recovery of 44%. The molecular weight of the enzyme was determined to be 62 kDa via SDS electrophoresis. Enzyme activity was optimal at pH 5.0 and 70 °C. The activation energy of the enzyme was calculated at a value of 20.0 ± 0.2 kJ/mol. The pH stability and thermostability of the purified laccase were studied. The enzyme was remarkably stable at pH 8.0 and at temperatures up to 40 °C. The thermal inactivation energy of the enzyme was determined to be 76.0 ± 1.2 kJ/mol. The thermodynamic parameters (ΔH*, ΔG*, and ΔS*) for the thermal deactivation of the purified laccase at a temperature range of 20–60 °C were: 73.8 ≤ ΔH* ≤ 74.3 kJ·mol⁻¹, 98.7 ≤ ΔG* ≤ 101.9 kJ·mol⁻¹, and −90.5 ≤ ΔS* ≤ −84.3 J·mol⁻¹·K⁻¹. Wine lees could be ideal substrates of fungal cultivation for laccase production and biomass with a high protein content in an eco-friendlier way. Full article