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The development and sustainability of second-generation biorefineries are essential for the production of high added value compounds and biofuels and their application at the industrial level. Pretreatment is one of the most critical stages in biomass processing. In this specific case, hydrothermal pretreatments (liquid hot water [LHW] and steam explosion [SE]) are considered the most promising process for the fractionation, hydrolysis and structural modifications of biomass. This review focuses on architecture of the plant cell wall and composition, fundamentals of hydrothermal pretreatment, process design integration, the techno-economic parameters of the solubilization of lignocellulosic biomass (LCB) focused on the operational costs for large-scale process implementation and the global manufacturing cost. In addition, profitability indicators are evaluated between the value-added products generated during hydrothermal pretreatment, advocating a biorefinery implementation in a circular economy framework. In addition, this review includes an analysis of environmental aspects of sustainability involved in hydrothermal pretreatments.

The avocado processing industry generates large amounts of avocado peels, which contain large amounts of high value-added compounds with antioxidant capabilities that have not yet been explored. Optimization of microwave-assisted extraction (MAE) of bioactive compounds from avocado peels with high antioxidant capacity was the objective of present work. Two experimental designs were implemented, using acetone 70% and ethanol at different concentrations, finding at 74.48 °C by 14.32 min and 66.37 °C by 0.97 min with 42.58% of ethanol as optimal conditions to obtain the highest antioxidant capacity, respectively. Optimized extracts with acetone and ethanol showed a high polyphenolic content (379.28 ± 19.35 and 354.43 ± 16.85 mg GAE/g dry extract, respectively); high antioxidant activity measured by DPPH (268.04 ± 25.11 and 233.85 ± 13.58 mgET/g dry extract, respectively); ABTS (895.19 ± 30.41 and 949.41 ± 7.42 mgET/g dry extract, respectively); ORAC (648.88 ± 28.66 and 692.06 ± 28.80 mgET/g dry extract, respectively), results reported for the first time. Fiber bonded phenolics compounds was extracted of MAE residues show a significant antioxidant activity. HPLC-MS analysis of optimized extracts showed the present of diverse phenolic acids, numerous procyanidins dimer A and B in different isomer shapes, catechin, epicatechin and perseitol.

The development of green technologies and bioprocesses such as solid-state fermentation (SSF) is important for the processing of macroalgae biomass and to reduce the negative effect of

Agave bagasse is one of the most abundant lignocellulosic residues readily available for valorization. The agave bagasse was pretreated by applying high-pressure CO2–H2O mixture at temperatures ranging from 150 to 190 °C for a residence time varying from 10 to 50 min. Subsequently, solid phase obtained from pretreatment was subject to enzymatic hydrolysis at high solid loadings. Under optimal conditions, the process integrating pretreatment followed by enzymatic hydrolysis yielded 75.8 mol% of the polysaccharides present in the biomass converted into oligo- or monosaccharides, providing 110.5 g/L of reducing sugars. The monosaccharides present in the obtained hydrolysate were successfully fermented into ethanol, demonstrating the feasibility of performing its biological conversion to commercial biofuels or biochemicals. Thereby, the present study has demonstrated the proof of concept of use of more sustainable high-pressure CO2–H2O pretreatment in the context of lignocellulosic residual biomass valorization based on the biochemical sugar platform. info:eu-repo/semantics/publishedVersion

Published online: 14 Jul 2020, Fermented food has been present throughout history, since fermentation not only helps preserving food, but also provides specific organoleptic characteristics typically associated to these foods. Most of the traditional fermented foods and artisanal beverages are produced by spontaneous generation, meaning no control of the microbiota, or the substrate used. Nevertheless, even not being standardized, they are an important source of bioactive compounds, such as antioxidant compounds, bioactive beeps, short chain fatty acids, amino acids, vitamins, and minerals. This review compiles a list of relevant traditional fermented beverages around the world, aiming to detail the fermentation process itselfincluding source of microorganisms, substrates, produced metabolites and the operational conditions involved. As well as to list the bioactive compounds present in each fermented food, together with their impact in the human health. Traditional fermented beverages from Mexico will be highlighted. These compounds are of high interest for the food, pharmaceutical and cosmetics industry. To scale-up the home fermentation processes, it is necessary to fully understand the microbiology and biochemistry behind these traditional products. The use of good quality raw materials with standardized methodologies and defined microorganisms, may improve and increase the production of the desirable bioactive compounds and open a market for novel functional products., The authors acknowledge the National Council of Science and Technology (CONACYT, Mexico) for the financial support (CVU 559365). This study was also supported by the Portuguese Foundation for Science and Technology under the scope of the strategic funding of UID/BIO/04469/2019 unit and BioTecNorte operation (NORTE-01- 0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte2020 - Programa Operacional Regional do Norte also, Project ColOsH 02/SAICT/2017 (POCI-01-0145- FEDER-030071)., info:eu-repo/semantics/publishedVersion

This review aims to present an analysis and discussion on the processing of lignocellulosic biomass in terms of biorefinery concept and circular bioeconomy operating at high solids lignocellulosic (above 15% [w/w]) at the pretreatment, enzymatic hydrolysis stage, and fermentation strategy for an integrated lignocellulosic bioprocessing. Studies suggest high solids concentration enzymatic hydrolysis for improved sugars yields and methods to overcome mass transport constraints. Rheological and computational fluid dynamics models of high solids operation through evaluation of mass and momentum transfer limitations are presented. Also, the review paper explores operational feeding strategies to obtain high ethanol concentration and conversion yield, from the hydrothermal pretreatment and investigates the impact of mass load over the operational techniques. Finally, this review contains a brief overview of some of the operations that have successfully scaled up and implemented high-solids enzymatic hydrolysis in terms of the biorefinery concept.

Sargassum spp. is a biomass that can potentially use as an alternative for bioethanol production. Hydrothermal processes (liquid hot water and steam explosion pretreatment) were carried out at different operational conditions. Enzymatic hydrolysis performed a preliminary test with different ratios 1:1 and 1:2 (cellulases and hemicellulases) of enzyme loading, once selected 1:2 ratio was obtained conversion yield of 99.91% and therefore carried a scale-up in stirred bioreactor getting 95.92% saccharification yield. Pre-simultaneous saccharification and fermentation strategy was performed in a continuous stirred tank bioreactor (CSTBR), producing ethanol yield of 57.69%, and for simultaneous saccharification and fermentation strategy was performed in a bubble column reactor was 71.37% ethanol yield. The energy efficiency was analyzed in different scenarios; the best data was 30.19 (g

This study evaluated different carbon and nitrogen sources on the growth and production of carbohydrates, protein, lipids, and chlorophyll of Spirulina platensis LEB-52 through an easy successive methodology under aqueous conditions. Spirulina platensis was cultivated at 120 rpm and light intensity of 156 µmol m−2 s−1 in a 500 mL Erlenmeyer flask with a working volume of 250 mL, using Zarrouk’s medium. The biomass, carbohydrate, and protein production together with the specific growth rate did not show a significant difference between NaHCO3 and Na2CO3. The salts of urea and ammonium are not an alternative nitrogen sources of low cost for Spirulina platensis cultivation. From the experimental results obtained in this study, a successful estimate of carbohydrate, protein, lipids, and chlorophyll content inside Spirulina platensis was achieved without use advanced analytical techniques, allowing saves resources and time. This method can be extrapolated to other microorganisms and cultivation regimens.

Hydrothermal processes are an attractive clean technology and cost-effective engineering platform for biorefineries based in the conversion of biomass to biofuels and high-value bioproducts under the basis of sustainability and circular bioeconomy. The deep and detailed knowledge of the structural changes by the severity of biomasses hydrothermal fractionation is scientifically and technological needed in order to improve processes effectiveness, reactors designs, and industrial application of the multi-scale target compounds obtained by steam explosion and liquid hot water systems. The concept of the severity factor [log10 (Ro)] established>30 years ago, continues to be a useful index that can provide a simple descriptor of the relationship between the operational conditions for biomass fractionation in second generation of biorefineries. This review develops a deep explanation of the hydrothermal severity factor based in lignocellulosic biomass fractionation with emphasis in research advances, pretreatment operations and the applications of severity factor kinetic model.

Agave bagasse is a residual biomass in the production of the alcoholic beverage tequila, and therefore, it is a promising raw material in the development of biorefineries using hot compressed water pretreatment (hydrothermal processing). Surfactants application has been frequently reported as an alternative to enhance monomeric sugars production efficiency and as a possibility to reduce the enzyme loading required. Nevertheless, the surfactants action mechanisms in the enzymatic hydrolysis is still not elucidated. In this work, hot compressed water pretreatment was applied on agave bagasse for biomass fractionation at 194 °C in isothermal regime for 30 min, and the effect of non-ionic surfactants (Tween 20, Tween 80, Span 80, and Polyethylene glycol (PEG 400)) was studied as a potential enhancer of enzymatic saccharification of hydrothermally pretreated solids of agave bagasse (AGB). It was found that non-ionic surfactants show an improvement in the conversion yield of cellulose to glucose (100%) and production of glucose (79.76 g/L) at 15 FPU/g glucan, the highest enhancement obtained being 7% regarding the control (no surfactant addition), using PEG 400 as an additive. The use of surfactants allows improving the production of fermentable sugars for the development of second-generation biorefineries., This project was funded by the Secretary of Public Education of Mexico—Mexican Science and Technology Council (SEP-CONACYT) with the Basic Science Project-2015-01 (Ref. 254808). Marcela Sofía Pino also thanks the National Council for Science and Technology (CONACYT, Mexico) for her Master Fellowship support (grant number: 611312/452636)., info:eu-repo/semantics/publishedVersion

The search of sustainable and environmentally friendly alternatives to obtain compounds for different industrial sectors has grown exponentially. Following the principles of biorefinery and circular bioeconomy, processes in which the use of natural resources such as macroalgae biomass is prioritized are required. This review focuses on a description of the relevance, application and engineering platforms of hydrothermal systems and the operational conditions depending on the target as an innovative technology and bio-based solution for macroalgae fractionation in order to recover profitable products for industries and investors. In this sense, hydrothermal treatments represent a promising alternative for obtaining different high value-added compounds from this biomass; since, the different variations in terms of operating conditions, gives great versatility to this technology compared to other types of processing, allowing it to be adapted depending on the objective, whether it is working under sub/super critical conditions, thus expanding its field of application.

El tomate es la hortaliza más cultivada y consumida a nivel mundial y frecuentemente sufre diversas tensiones ambientales que afectan su productividad. Como posibles soluciones para mitigar el estrés está el uso de bioestimulantes, en particular, el uso de extractos de algas pardas que afectan positivamente varios procesos fisiológicos y bioquímicos en las plantas. Por lo tanto, el objetivo del presente trabajo fue evaluar el efecto de la aplicación foliar de 17 extractos hidroalcohólicos de Sargassum spp. al 1.5%, más dos tratamientos control (agua destilada y un producto comercial a base de Ascophyllum nodosum) sobre el crecimiento y compuestos antioxidantes de plántulas de tomate, bajo un diseño completamente al azar. Los resultados muestran que el extracto que presentó los mejores resultados fue el EAS7 (160 °C / 30 min / 50% de etanol). Dicho extracto aumentó la altura, diámetro de tallo, materia fresca y seca total de las plántulas de tomate en un 8.67, 32.32, 25.03 y 11.59%, respectivamente, encomparación con el control absoluto (agua destilada). Además, el EAS7 aumentó el contenido de proteínas, glutatión, fenoles totales, flavonoides y capacidad antioxidante (ABTS) de las hojas en un 386.48, 15.92, 22.05, 35.99 y 18.86%, respectivamente, en comparación con el control absoluto. La aplicación de extractos de Sargassum spp. es una alternativa prometedora para mejorar lascaracterísticas agronómicas y antioxidantes del cultivo de tomate.

Fusarium oxysporum es uno de los patógenos más destructivos con gran distribución y efectos devastadores en hortalizas. Una alternativa para mitigar el daño por F. oxysporum es el uso de bioestimulantes, ya que promueven una respuesta de defensa en situaciones de estrés. El objetivo del presente trabajo fue evaluar el potencial bioestimulante de extractos hidroalcohólicos de Sargassum spp. (SAR) para incrementar la tolerancia a la infección por F. oxysporum en plántulas de tomate. En total se evaluaron 17 extractos, los cuales se aplicaron de manera foliar a las plántulas a los 7, 12, 22, 33 y 43 ddt (días después del trasplante). La inducción de tolerancia de los extractos de SAR se evaluó en términos de incidencia y severidad de la enfermedad y variables agronómicas. El extracto E12 mostró un mejor control de la enfermedad con un 17% menos de la severidad de síntomas respecto al testigo infectado.

Edible mushrooms used as a protein-rich food may be an attractive alternative to conventional protein sources, while promoting its valorization. This work aimed to obtain a protein concentrate from a Pleurotus ostreatus mushroom flour, its characterization, and nutritional and functional properties evaluation. Methodologies applied for extraction and precipitation of protein were optimized - pH 4 and 12, respectively; and flour-solvent ratio of 1:20 w/v. The protein density was increased by 78 %. P. ostreatus flour and concentrate were characterized by proximal composition. The content of total phenolic compounds in the protein concentrate decreased, leading to a positive effect on protein digestibility, while the DPPH radical scavenging activity was not significantly affected. Peptides with molecular weights from 12 to 35 kDa, with possible bioactivity, were identified by electrophoresis. Protein digestibility assessed by in vitro gastrointestinal digestion showed a 4.2-fold higher hydrolysis degree in the protein concentrate than the flour., This study was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UIDB/04469/2020 unit and BioTecNorte operation (NORTE–01–0145–FEDER-000004) funded by the European Regional Development Fund under the scope of Norte 2020–Programa Operacional Regional do Norte and the Project ColOsH PTDC/BTM–SAL/30071/2017 (POCI–01–0145–FEDER–030071). The authors also acknowledge the grant for a postgraduate scholarship (CVU number 922722) provided by National Council of Science and Technology (CONACYT) Mexico., info:eu-repo/semantics/publishedVersion

One of the major challenges in biofuels production from lignocellulosic biomass is the generation of high glucose titers from cellulose in the enzymatic hydrolysis stage of pretreated biomass to guarantee a cost-effective process. Therefore, the enzymatic saccharification on cellulose at high solid loading is an alternative. In this work, the agave bagasse was hydrothermally pretreated and optimized at 194°C/30min, obtaining a pretreated solid rich in cellulose content (>46.46%), and subjected to enzymatic hydrolysis at high solid levels. A horizontal bioreactor was designed for enzyme saccharification at high solid loadings [25% (w/v)]. The bioreactor improved mixing efficiency, with cellulose conversions up to 98% (195.6g/L at 72h). Moreover, mathematical modeling of cellulase deactivation demonstrated that cellulases lose most of their initial activity in the first hours of the reaction. Also, cellulose was characterized by X-ray diffraction, and the pretreated solids were visualized using scanning electron microscopy., This project was funded by the Secretary of Public Education of Mexico - Mexican Science and Technology Council (SEP-CONACYT) with the Basic Science Project-2015-01 (Ref. 254808). Marcela Sofía Pino also thanks the National Council for Science and Technology (CONACYT, Mexico) for her Master Fellowship support (grant number: 611312/452636), and Dr. Michele Michelin thanks the Portuguese Foundation for Science and Technology (FCT) for her postdoctoral fellowship (SFRH/BPD/100786/2014)., info:eu-repo/semantics/publishedVersion

This work focuses on the effect of subcritical water pretreatment conditions on agave bagasse chemical composition, biomass fractionation, and enzymatic hydrolysis obtained from the different tequila production processes. The pretreatment was carried out in a batch pressurized reactor within an isothermal regime. The operational conditions for subcritical water pretreatment were (150–190 °C) and (10–50 min). The best operational conditions were selected, based on the increased cellulose content (>50%) in the pretreated solid phase. The conditions for 190 °C for 50 and 30 min of pretreated agave bagasse solids were chosen for enzymatic hydrolysis susceptibility (15 FPU/g of the substrate). The maximum conversion yield (cellulose to glucose) during enzymatic hydrolysis achieved was up to 61.62% (5.86 g/L) in industrial bagasse at 72 h and initial saccharification rate was 0.34 g/(L*h) at 12 h. This study indicates that the agave bagasse is a promising raw material in the development of second-generation biorefineries.

Formerly it was considered that the diet was only consuming food that provided nutrients to meet the metabolic requirements and vital functions of the individual...

Avocado seeds are an agroindustrial residue widely produced in Mexico that are causing various environmental problems due to their accumulation. The evaluation of avocado residues to recover biopolymers by microwave-assisted extraction (MAE) and the characterization of avocado starch properties were studied in the present work. A central-composite design was used to optimize the MAE process. Moreover, a comparison was performed between MAE non-isothermal mode (NO&ndash, ISO) and conventional extraction. Starch optimization by MAE was obtained at 161.09 &deg, C for 56.23 min with an extraction yield of 49.52% &plusmn, 0.69%, while with NO&ndash, ISO at 161 &deg, C was obtained 45.75% &plusmn, 2.18%. Conventional extraction was 39.04% &plusmn, 2.22%. Compared with conventional starch, MAE starch showed similar proprieties and molecular spectra. In contrast, MAE starch showed high solubility, low water absorption capacity, a non-granular structure with small particle size (&lt, 2 &micro, m) and polydispersity of fragments at different sizes of polymers. Therefore, MAE is a viable technology to extract the starch, and avocado seed can be considered an excellent starch source for the development of novel functional foods, contributing to promoting sustainability across the food chain.

Lignocellulosic biomass, fruit, and vegetable waste are nowadays being a potential feedstock for biofuels production and compounds with high added-value with applications in food, energy, and materials industries in terms of biorefinery, impacting in the circular bioeconomy. Therefore, in this chapter, an overview of the status of biorefineries development, fractionation of 396biomass using hydrothermal and acid pretreatment, purification of lignocellulosic residual biomass hydrolysates after pretreatment and high added-value compounds as bioplastics, xylooligosaccharides (XOS), xylitol, and enzymes is presented.

Avocado seeds are an agroindustrial residue produced largely by avocado processing industries, which is accumulated in high quantities because it has low reuse due to its poor revalorization. The optimization of Microwave-Assisted Extraction (MAE) of bioactive compounds with high antioxidant capacity from avocado seeds were studied in the present work for the first time. Applying two experimental designs, using acetone 70 % and ethanol, the optimal conditions of extraction were found: 72.18 °C for 19.01 min and 71.64 °C for 14.69 min with 58.51 % of ethanol, respectively, to obtain extracts with highest antioxidant activity. The optimized extracts obtained with acetone and ethanol showed a high polyphenolic content (307.09 ± 14.16 and 254.40 ± 16.36 mg GAE/g extract) and high antioxidant activity measured by DPPH (266.56 ± 2.76 and 221.69 ± 20.12 mg ET/g extract), ABTS (607.28 ± 4.71 and 516.34 ± 11.81 mg ET/g extract) and ORAC (475.55 ± 47.82 and 495.25 ± 14.52 mg ET/g extract), proving MAE as a better technique than those previously reported for avocado seeds. Fiber residues obtained after MAE showed bonded phenolics compounds with relevant antioxidant activity, those obtained with ethanol. HPLC-ESI-MS analysis showed the presence of 20 different identified compounds, including phenolic acids, procyanidins dimer B and trimer A and B in different isomers forms, catechin, epicatechin and perseitol. MAE is a green, energy efficient and rapid tool for extractions of bioactive components from avocado seedswithout affecting their antioxidant activities representing an attractive alternative protocol in traditional herbal industry and medicine.

Macroalgae is a large group of plant-like organisms that dovetail into the third generation of renewable feedstocks within the biorefinery context, which implies a conversion of biomass to generate multiple biobased products such as biofuels. These could be bioethanol, biogas, bio-oil, biodiesel, biohydrogen, and biobutanol, amongst others. The storage components of macroalgae, namely carbohydrates and lipids, and the absence or near absence of lignin, make macroalgae an attractive raw material for conversion into biofuels. In this review, we detail some of the foremost pathways used in macroalgal biofuel production and discuss the respective advantages and problems associated with each development. The diverse range of different macroalgal species that have been utilized for biofuel production, alongside their biochemical composition and feasibility for large-scale cultivation, will also be addressed herein. Lastly, Mexico's status regarding energy dependence and biofuels production are discussed and how the country's current battle with an invasive species that is overpopulating its shoreline could become beneficial for biofuel production.

The dependence on non-renewable resources, particularly fossil fuels, has awaken a growing interest in research of sustainable alternative energy sources, such as bioethanol. The production of bioethanol from lignocellulosic materials comprises three main stages, starting with a pretreatment, followed by an enzymatic hydrolysis step where fermentable sugars are obtained for the final fermentation process. Enzymatic hydrolysis represents an essential step in the bioethanol production, however there are some limitations in it that hinders the process to be economically feasible. Different strategies have been studied to overcome these limitations, including the enzyme recycling and the utilization of high solids concentrations. Several investigations have been carried out in different bioreactor configurations with the aim to obtain higher yields of glucose in the enzymatic hydrolysis stage; however, the commonest are Stirred Tank Bioreactors (STBR) and Membrane Bioreactors (MBR). In general, the key criteria for a bioreactor design include adequate mass transfer, low shear stress, and efficient mixing that allows the appropriated interaction between the substrate and the enzyme. Therefore, this review will address the main aspects to be considered for a bioreactor design, as well as, the operational conditions, some characteristics and mode of operating strategies of the two main bioreactors used in the enzymatic hydrolysis stage. Moreover, two types of pneumatically agitated bioreactors, namely bubble column and gas-lift bioreactors, are discussed as promising alternatives to develop enzymatic saccharification due to their low energy consumption compared with STBR., This work was financial supported by the Secretary of Public Education of Mexico – Mexican Science and Technology Council (SEPCONACYT) with the Basic Science Project-2015-01 (Ref. 254808), and the Energy Sustainability Fund 2014-05 (CONACYT-SENER), Mexican Centre for Innovation in Bioenergy (Cemie-Bio), and Cluster of Bioalcohols (Ref. 249564). The author Marcela Pino also thanks the National Council for Science and Technology (CONACYT, Mexico) for her Master Fellowship support (grant number: 611312/452636)., info:eu-repo/semantics/publishedVersion

The production of tequila in Mexico generates a large amount of agave bagasse per year. However, this biomass can be considered as a potential source for biofuel production. In this study, it is described how the hydrothermal pretreatment was scaled in a bench scale, considering the severity index as a strategy. The best condition was at 180°C in isothermal regime for 20min with 65.87% of cellulose content and high concentration of xylooligosaccharides (15.31g/L). This condition was scaled up (using severity factor: [logR0]=4.11), in order to obtain a rich pretreated solid in cellulose to perform the enzymatic hydrolysis, obtaining saccharification yields of 98.5 and 99.5% at high-solids loading (10 and 15%, respectively). The pre-saccharification and fermentation strategy was used in the bioethanol production at 10 and 15% of total pretreated solids, obtaining 38.39 and 55.02g/L of ethanol concentration, corresponding to 90.84% and 87.56% of ethanol yield, respectively., Financial support is gratefully acknowledged from the Energy Sustainability Fund 2014-05 (CONACYT-SENER), Mexican Centre for Innovation in Bioenergy (Cemie-Bio), Cluster of Bioalcohols (Ref. 249564). We gratefully acknowledge support for this research by the Mexican Science and Technology Council (CONACYT, Mexico) for the Infrastructure Project – INFR201601 (Ref. 269461) and Basic Science Project – 2015-01 (Ref. 254808). Author Daniela L. Aguilar would like to thank the Mexican Science and Technology Council (CONACY, Mexico) for their master fellowship support (grant number: 582801/ 414478) andauthor ElisaZanuso thanksthe EnergySustainability Fund 2014-05 (CONACYT-SENER, Ref. 249564) for the undergraduate fellowship granted. Also, the authors thank Prof. Lucília Domingues and José Teixeira (University of Minho, Portugal) for kindly providing the yeast strain., info:eu-repo/semantics/publishedVersion

Macroalgae is an emerging third-generation feedstock and promising biomass within the biorefinery context to produce biofuels and high-added value compounds. Biorefinery involves processes and technologies in the context of sustainable bioeconomy. Throughout the biorefinery process is important not to neglect parameters and conditions that can impact the optimization, such as pretreatment, solid loading in enzymatic hydrolysis and, fermentation. In this case, the techno-economic analysis allows designing a feasible process of macroalgae valorization considering differents important parameters for scaling up the process for biofuels and chemicals to approach all these compounds for a future market and commercial. According to these arguments, this review aims to describe the macroalgae biorefinery, applications, and techno-economic analysis to provide the general panorama of economic feasibility for the valorization of macroalgae biomass in terms of biorefinery and circular bioeconomy.