Publications by authors named "Hector A Ruíz"

21 Publications

  • Page 1 of 1

High-pressure technology for Sargassum spp biomass pretreatment and fractionation in the third generation of bioethanol production.

Bioresour Technol 2021 Jun 6;329:124935. Epub 2021 Mar 6.

Biorefinery Group, Food Research Department, Faculty of Chemistry Sciences, Autonomous University of Coahuila, 25280 Saltillo, Coahuila, Mexico. Electronic address:

Sargassum spp is an invasive macroalgae and an alternative feedstock for bioethanol production. Sargassum spp biomass was subjected to high-pressure technology for biomass fractionation under different operating conditions of temperature and residence time to obtain glucan enriched pretreated solids (32.22 g/100 g of raw material). Enzyme hydrolysis process at high pretreated solid loading (13%, w/v) and enzyme loading of 10 FPU/g of glucan was performed, obtaining 43.01 g/L of glucose corresponding to a conversion yield of 92.12%. Finally, a pre-simultaneous saccharification and fermentation strategy (PSSF) was performed to produce bioethanol. This operational strategy produced 45.66 g/L of glucose in the pre-saccharification stage, and 18.14 g/L of bioethanol was produced with a glucose to bioethanol conversion yield of 76.23%. The development of this process highlights the feasibility of bioethanol production from macroalgal biomass in the biorefinery concept.
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http://dx.doi.org/10.1016/j.biortech.2021.124935DOI Listing
June 2021

Microbial co-culturing strategies for the production high value compounds, a reliable framework towards sustainable biorefinery implementation - an overview.

Bioresour Technol 2021 Feb 5;321:124458. Epub 2020 Dec 5.

Biorefinery Group, Food Research Department, Faculty of Chemistry Sciences, Autonomous University of Coahuila, 25280 Saltillo, Coahuila, Mexico. Electronic address:

The microbial co-cultures or consortia are a natural set of microorganisms formed from different species or the same species but different strains, in which members can interact with each other. The co-culture systems have wide variety of technological applications such as the production of foods, treatment of wastewater, removal of toxic substances, environmental recovery, and all these without the need to work in sterile conditions. Therefore, the need of understanding communication mechanisms between cell-to-cell within co-culture will allow to construct and to program their biological behavior from the use of complex substrates to produce biocompounds. The technology of co-culture systems enables the development of biorefinery platforms to obtain biofuels, and high value compounds through biomass transformation by sustainable process. This review focuses on understanding the roles of consortia microbial to design and built co-culture systems to produce high value compounds in terms a sustainable biorefinery.
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http://dx.doi.org/10.1016/j.biortech.2020.124458DOI Listing
February 2021

Spontaneously fermented traditional beverages as a source of bioactive compounds: an overview.

Crit Rev Food Sci Nutr 2020 Jul 14:1-23. Epub 2020 Jul 14.

Food Research Department, School of Chemical Sciences, Autonomous University of Coahuila, Saltillo Coahuila, Saltillo, Coahuila, Mexico.

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 itself-including 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.
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http://dx.doi.org/10.1080/10408398.2020.1791050DOI Listing
July 2020

Engineering aspects of hydrothermal pretreatment: From batch to continuous operation, scale-up and pilot reactor under biorefinery concept.

Bioresour Technol 2020 Mar 25;299:122685. Epub 2019 Dec 25.

Protein Chemistry and Enzyme Technology, DTU Bioengineering, Department of Biotechnology and Biomedicine, Technical University of Denmark, DK-2800 Lyngby, Denmark.

Different pretreatments strategies have been developed over the years mainly to enhance enzymatic cellulose degradation. In the new biorefinery era, a more holistic view on pretreatment is required to secure optimal use of the whole biomass. Hydrothermal pretreatment technology is regarded as very promising for lignocellulose biomass fractionation biorefinery and to be implemented at the industrial scale for biorefineries of second generation and circular bioeconomy, since it does not require no chemical inputs other than liquid water or steam and heat. This review focuses on the fundamentals of hydrothermal pretreatment, structure changes of biomass during this pretreatment, multiproduct strategies in terms of biorefinery, reactor technology and engineering aspects from batch to continuous operation. The treatise includes a case study of hydrothermal biomass pretreatment at pilot plant scale and integrated process design.
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http://dx.doi.org/10.1016/j.biortech.2019.122685DOI Listing
March 2020

Consolidated Bioprocess for Bioethanol Production from Raw Flour of Seeds Using the Native Strain of Bm-2.

Microorganisms 2019 Oct 23;7(11). Epub 2019 Oct 23.

Renewable Energy Department, Yucatan Center for Scientific Research, Merida 97302, Mexico.

Consolidated bioprocessing (CBP), which integrates biological pretreatment, enzyme production, saccharification, and fermentation, is a promising operational strategy for cost-effective ethanol production from biomass. In this study, the use of a native strain of (Bm-2) was evaluated for bioethanol production from in a CBP. The raw seed flour obtained from the ramon tree contained 61% of starch, indicating its potential as a raw material for bioethanol production. Quantitative assays revealed that the Bm-2 strain produced the amylase enzyme with activity of 193.85 U/mL. The Bm-2 strain showed high tolerance to ethanol stress and was capable of directly producing ethanol from raw flour at a concentration of 13 g/L, with a production yield of 123.4 mL/kg flour. This study demonstrates the potential of Bm-2 for starch-based ethanol production in a consolidated bioprocess to be implemented in the biofuel industry. The residual biomass after fermentation showed an average protein content of 22.5%, suggesting that it could also be considered as a valuable biorefinery co-product for animal feeding.
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http://dx.doi.org/10.3390/microorganisms7110483DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6920830PMC
October 2019

Emerging strategies for the development of food industries.

Bioengineered 2019 12;10(1):522-537

Bioprocesses and Bioproducts Research Group, Food Research Department, School of Chemistry, Autonomous University of Coahuila, Saltillo, Mexico.

Undoubtedly, the food industry is undergoing a dynamic process of transformation in its continual development in order to meet the requirements and solve the great problems represented by a constantly growing global population and food claimant in both quantity and quality. In this sense, it is necessary to evaluate the technological trends and advances that will change the landscape of the food processing industry, highlighting the latest requirements for equipment functionality. In particular, it is crucial to evaluate the influence of sustainable green biotechnology-based technologies to consolidate the food industry of the future, today, and it must be done by analyzing the mega-consumption trends that shape the future of industry, which range from local sourcing to on-the-go food, to an increase in organic foods and clean labels (understanding ingredients on food labels). While these things may seem alien to food manufacturing, they have a considerable influence on the way products are manufactured. This paper reviews in detail the conditions of the food industry, and particularly analyzes the application of emerging technologies in food preservation, extraction of bioactive compounds, bioengineering tools and other bio-based strategies for the development of the food industry.
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http://dx.doi.org/10.1080/21655979.2019.1682109DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6844418PMC
December 2019

Enhancement and modeling of enzymatic hydrolysis on cellulose from agave bagasse hydrothermally pretreated in a horizontal bioreactor.

Carbohydr Polym 2019 May 8;211:349-359. Epub 2019 Feb 8.

Biorefinery Group, Food Research Department, Faculty of Chemistry Sciences, Autonomous University of Coahuila, Saltillo, Coahuila 25280, Mexico; Cluster of Bioalcohols, Mexican Centre for Innovation in Bioenergy (Cemie-Bio), Mexico. Electronic address:

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/30 min, 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% (195.6 g/L at 72 h). 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.
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http://dx.doi.org/10.1016/j.carbpol.2019.01.111DOI Listing
May 2019

Scale-up and evaluation of hydrothermal pretreatment in isothermal and non-isothermal regimen for bioethanol production using agave bagasse.

Bioresour Technol 2018 Sep 30;263:112-119. Epub 2018 Apr 30.

Biorefinery Group, Food Research Department, Faculty of Chemistry Sciences, Autonomous University of Coahuila, Saltillo, Coahuila 25280, Mexico; Cluster of Bioalcohols, Mexican Centre for Innovation in Bioenergy (Cemie-Bio), Mexico. Electronic address:

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 20 min with 65.87% of cellulose content and high concentration of xylooligosaccharides (15.31 g/L). This condition was scaled up (using severity factor: [logR] = 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 55.02 g/L of ethanol concentration, corresponding to 90.84% and 87.56% of ethanol yield, respectively.
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http://dx.doi.org/10.1016/j.biortech.2018.04.100DOI Listing
September 2018

Multi-step approach to add value to corncob: Production of biomass-degrading enzymes, lignin and fermentable sugars.

Bioresour Technol 2018 Jan 20;247:582-590. Epub 2017 Sep 20.

CEB - Centre of Biological Engineering, University of Minho, Campus Gualtar, 4710-057 Braga, Portugal.

This work presents an integrated and multi-step approach for the recovery and/or application of the lignocellulosic fractions from corncob in the production of high value added compounds as xylo-oligosaccharides, enzymes, fermentable sugars, and lignin in terms of biorefinery concept. For that, liquid hot water followed by enzymatic hydrolysis were used. Liquid hot water was performed using different residence times (10-50min) and holding temperature (180-200°C), corresponding to severities (log(R)) of 3.36-4.64. The most severe conditions showed higher xylo-oligosaccharides extraction (maximum of 93%) into the hydrolysates and higher recovery of cellulose on pretreated solids (maximum of 65%). Subsequently, hydrolysates and solids were used in the production of xylanases and cellulases, respectively, as well as, pretreated solids were also subjected to enzymatic hydrolysis for the recovery of lignin and fermentable sugars from cellulose. Maximum glucose yield (100%) was achieved for solids pretreated at log(R) of 4.42 and 5% solid loading.
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http://dx.doi.org/10.1016/j.biortech.2017.09.128DOI Listing
January 2018

Comparison of physicochemical pretreatments of banana peels for bioethanol production.

Food Sci Biotechnol 2017 24;26(4):993-1001. Epub 2017 Jul 24.

1Nanobioscience and Biorefinery Groups, Food Research Department, Chemistry School, Autonomous University of Coahuila, Blvd. V. Carranza e Ing. José Cárdenas Valdés, 25280 Saltillo, Coahuila Mexico.

Pretreatments with different concentrations of sulfuric acid (0, 0.5, and 1% v/v) and temperatures (28 and 121 °C at 103 kPa in an autoclave) were performed on banana peels (BP) milled by mechanical grinding and grinding in a blender as well as without grinding. Cellulose, hemicellulose, lignin, ash, and total and reducing sugar contents were evaluated. The highest yields of cellulose enzymatic hydrolysis (99%) were achieved with liquefied autoclaved BP treated with 0.5 and 1% acid after 48 h of hydrolysis. Ethanol production by fermentation was assayed using hydrolyzed BP at 10, 15, and 20% (w/w). The highest ethanol level (21 g/L) was reached after 24 h of fermentation with 20% (w/w) BP. Kinetics of the consumption of reducing sugars under this fermentation condition demonstrates the presence of a period (about 8 h). Thus, BP are a good source for ethanol production.
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http://dx.doi.org/10.1007/s10068-017-0128-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6049549PMC
July 2017

Comparison of microwave and conduction-convection heating autohydrolysis pretreatment for bioethanol production.

Bioresour Technol 2017 Nov 20;243:273-283. Epub 2017 Jun 20.

Biorefinery Group, Food Research Department, School of Chemistry, Autonomous University of Coahuila, 25280 Saltillo, Coahuila, Mexico; Cluster of Bioalcohols, Mexican Centre for Innovation in Bioenergy (Cemie-Bio), Mexico. Electronic address:

This work describes the application of two forms of heating for autohydrolysis pretreatment on isothermal regimen: conduction-convection heating and microwave heating processing using corn stover as raw material for bioethanol production. Pretreatments were performed using different operational conditions: residence time (10-50 min) and temperature (160-200°C) for both pretreatments. Subsequently, the susceptibility of pretreated solids was studied using low enzyme loads, and high substrate loads. The highest conversion was 95.1% for microwave pretreated solids. Also solids pretreated by microwave heating processing showed better ethanol conversion in simultaneous saccharification and fermentation process (92% corresponding to 33.8g/L). Therefore, microwave heating processing is a promising technology in the pretreatment of lignocellulosic materials.
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http://dx.doi.org/10.1016/j.biortech.2017.06.096DOI Listing
November 2017

Rhizopus oryzae - Ancient microbial resource with importance in modern food industry.

Int J Food Microbiol 2017 Sep 15;257:110-127. Epub 2017 Jun 15.

Food Research Dept. School of Chemistry, Universidad Autónoma de Coahuila, Saltillo 25280, Coahuila, Mexico. Electronic address:

Filamentous fungi are microorganisms widely known for their diverse biochemical features. Fungi can efficiently invade a wide variety of substrates under operational conditions producing numerous bioproducts of interest, such as enzymes, organic acids, aromatic compounds and colorants. An additional interesting characteristic of some fungi is their safety classification for different uses, which guarantees that the bioproducts obtained from them do not contain any toxic component deleterious to humans. Rhizopus oryzae is among this group of fungi and is classified as a GRAS filamentous fungus, commonly used for production of some oriental traditional foods. It is mainly recognized as a good producer of lactic acid; however, its potential for other biotechnological processes is under study. This review analyzes and discusses the current scientific and technical contributions which may maximize the potential of R. oryzae as a producer of different compounds of industrial interest.
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http://dx.doi.org/10.1016/j.ijfoodmicro.2017.06.012DOI Listing
September 2017

Process alternatives for bioethanol production from mango stem bark residues.

Bioresour Technol 2017 Sep 3;239:430-436. Epub 2017 May 3.

Nanobioscience and Biorefinery Group, Food Research Department, School of Chemistry, Autonomous University of Coahuila, Saltillo, Coah., Mexico. Electronic address:

Three alternatives for bioethanol production from pretreated mango stem bark after maceration (MSBAM) were evaluated as a biorefinery component for the mango agroindustry. These included separate hydrolysis and fermentation (SHF), simultaneous saccharification and fermentation (SSF), and pre-saccharification followed by simultaneous saccharification and fermentation (PSSF). The effects on ethanol concentration, yield and productivity of pretreated MSBAM solids loading, Tween 20 addition, and temperature were used for process comparisons. The highest yields for the SHF, SSF, and PSSF process alternatives were 58.8, 81.6, and 84.5%, respectively. Since saccharification and fermentation are carried out in the same vessel in the SSF alternative, and no significant SSF and PSSF differences in ethanol concentration were observed, SSF is recommended as the best process configuration.
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http://dx.doi.org/10.1016/j.biortech.2017.04.131DOI Listing
September 2017

Trichoderma sp. spores and Kluyveromyces marxianus cells magnetic separation: Immobilization on chitosan-coated magnetic nanoparticles.

Prep Biochem Biotechnol 2017 Jul 29;47(6):554-561. Epub 2016 Dec 29.

e Biotechnology Department, ICIDCA - Cuban Research Institute of Derivatives Sugarcane , La Habana , Cuba.

In the present study, the interactions between chitosan-coated magnetic nanoparticles (C-MNP) and Trichoderma sp. spores as well as Kluyveromyces marxianus cells were studied. By Plackett-Burman design, it was demonstrated that factors which directly influenced on yeast cell immobilization and magnetic separation were inoculum and C-MNP quantity, stirring speed, interaction time, and volume of medium, while in the case of fungal spores, the temperature also was disclosed as an influencing factor. Langmuir and Freundlich models were applied for the mathematical analysis of adsorption isotherms at 30°C. For Trichoderma sp. spore adsorption isotherm, the highest correlation coefficient was observed for lineal function of Langmuir model with a maximum adsorption capacity at 5.00E + 09 spores (C-MNP g). Adsorption isotherm of K. marxianus cells was better adjusted to Freundlich model with a constant (K) estimated as 2.05E + 08 cells (C-MNP g). Both systems may have a novel application in fermentation processes assisted with magnetic separation of biomass.
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http://dx.doi.org/10.1080/10826068.2016.1275007DOI Listing
July 2017

Evaluation of agave bagasse recalcitrance using AFEX™, autohydrolysis, and ionic liquid pretreatments.

Bioresour Technol 2016 Jul 22;211:216-23. Epub 2016 Mar 22.

Joint BioEnergy Institute, Physical Biosciences Division, Lawrence Berkeley National Laboratory, Emeryville, CA, United States; Sandia National Laboratories, Biological and Engineering Sciences Center, Livermore, CA, United States.

A comparative analysis of the response of agave bagasse (AGB) to pretreatment by ammonia fiber expansion (AFEX™), autohydrolysis (AH) and ionic liquid (IL) was performed using 2D nuclear magnetic resonance (NMR) spectroscopy, wet chemistry, enzymatic saccharification and mass balances. It has been found that AFEX pretreatment preserved all carbohydrates in the biomass, whereas AH removed 62.4% of xylan and IL extracted 25% of lignin into wash streams. Syringyl and guaiacyl lignin ratio of untreated AGB was 4.3, whereas for the pretreated biomass the ratios were 4.2, 5.0 and 4.7 for AFEX, AH and IL, respectively. Using NMR spectra, the intensity of β-aryl ether units in aliphatic, anomeric, and aromatic regions decreased in all three pretreated samples when compared to untreated biomass. Yields of glucose plus xylose in the major hydrolysate stream were 42.5, 39.7 and 26.9kg per 100kg of untreated AGB for AFEX, IL and AH, respectively.
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http://dx.doi.org/10.1016/j.biortech.2016.03.103DOI Listing
July 2016

Industrial robust yeast isolates with great potential for fermentation of lignocellulosic biomass.

Bioresour Technol 2014 Jun 20;161:192-9. Epub 2014 Mar 20.

CEB - Centre of Biological Engineering, Universidade do Minho, Campus de Gualtar, 4710-057 Braga, Portugal. Electronic address:

The search of robust microorganisms is essential to design sustainable processes of second generation bioethanol. Yeast strains isolated from industrial environments are generally recognised to present an increased stress tolerance but no specific information is available on their tolerance towards inhibitors that come from the pretreatment of lignocellulosic materials. In this work, a strategy for the selection of different yeasts using hydrothermal hydrolysate from Eucalyptus globulus wood, containing different concentrations of inhibitors, was developed. Ten Saccharomyces cerevisiae and four Kluyveromyces marxianus strains isolated from industrial environments and four laboratory background strains were evaluated. Interestingly, a correlation between final ethanol titer and percentage of furfural detoxification was observed. The results presented here highlight industrial distillery environments as a remarkable source of efficient yeast strains for lignocellulosic fermentation processes. Selected strains were able to resourcefully degrade furfural and HMF inhibitors, producing 0.8g ethanol/Lh corresponding to 94% of the theoretical yield.
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http://dx.doi.org/10.1016/j.biortech.2014.03.043DOI Listing
June 2014

Biorefinery valorization of autohydrolysis wheat straw hemicellulose to be applied in a polymer-blend film.

Carbohydr Polym 2013 Feb 29;92(2):2154-62. Epub 2012 Nov 29.

IBB - Institute for Biotechnology and Bioengineering, Centre of Biological Engineering, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal.

The aims of this study were the extraction of hemicellulose from wheat straw (WS) and its utilization in the reinforcement of a κ-carrageenan/locust bean gum (κ-car/LBG) polymeric blend films (PBFs). WS hemicellulose extraction was performed under autohydrolysis process and hemicellulose extracted (HE) under optimum condition was used in PBFs. PBFs were prepared varying different proportions of HE into the κ-car/LBG film-forming solutions. Barrier properties (water vapor permeability, WVP), mechanical properties (tensile-strength, TS and elongation-at-break, EB), moisture content, opacity and thermal properties of the resulting PBFs were determined and related with the incorporation of HE. The 2-3-2 proportion (in the high ratio) of PBF (κ-car/LBG/HE) causes a slight decrease of WVP and an increase of the TS, thus resulting in an improvement of the physical properties of PBFs. HE showed to be a promising material in order to reinforce κ-car/LBG PBF and can be an alternative in the application of hemicellulose according to biorefinery concept.
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http://dx.doi.org/10.1016/j.carbpol.2012.11.054DOI Listing
February 2013

A new approach on Brewer's spent grains treatment and potential use as lignocellulosic yeast cells carriers.

J Agric Food Chem 2012 Jun 1;60(23):5994-9. Epub 2012 Jun 1.

Department of Biological Engineering, University of Minho , Campus Gualtar, 4710-057, Braga, Portugal.

The major objective of this work is to improve the pretreatments of brewer's spent grains (BSG) aiming at their use as a source for lignocellulosic yeast carriers (LCYC) production. Therefore, several pretreatments of BSG have been designed aiming at obtaining various yeast carriers, differing on their physicochemical composition. Cellulose, hemicellulose, lignin, fat, protein, and ash content were determined for crude BSG and the LCYCs. The long chain fatty acids profile for the crude BSG was also analyzed. Chemical treatments successfully produced several different LCYC based on BSG. The highest cellulose content in LCYC was achieved upon application of caustic (NaOH) treatment during 40 min. Either caustic or combined acid-caustic treatments predominately generated hydrophobic, negatively charged LCYC. The feasibility of using BSG for LCYC production is strengthened by the fact that added-value byproduct can be extracted before the chemical treatments are applied.
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http://dx.doi.org/10.1021/jf300299mDOI Listing
June 2012

Production of xylanase and β-xylosidase from autohydrolysis liquor of corncob using two fungal strains.

Bioprocess Biosyst Eng 2012 Sep 26;35(7):1185-92. Epub 2012 Feb 26.

Institute for Biotechnology and Bioengineering (IBB), Centre of Biological Engineering, University of Minho, Braga, Portugal.

Agroindustrial residues are materials often rich in cellulose and hemicellulose. The use of these substrates for the microbial production of enzymes of industrial interest is mainly due to their high availability associated with their low cost. In this work, corncob (CCs) particles decomposed to soluble compounds (liquor) were incorporated in the microbial growth medium through autohydrolysis, as a strategy to increase and undervalue xylanase and β-xylosidase production by Aspergillus terricola and Aspergillus ochraceus. The CCs autohydrolysis liquor produced at 200 °C for 5, 15, 30 or 50 min was used as the sole carbon source or associated with untreated CC. The best condition for enzyme synthesis was observed with CCs submitted to 30 min of autohydrolysis. The enzymatic production with untreated CCs plus CC liquor was higher than with birchwood xylan for both microorganisms. A. terricola produced 750 total U of xylanase (144 h cultivation) and 30 total U of β-xylosidase (96-168 h) with 0.75% untreated CCs and 6% CCs liquor, against 650 total U of xylanase and 2 total U of β-xylosidase in xylan; A. ochraceus produced 605 total U of xylanase and 56 total U of β-xylosidase (168 h cultivation) with 1% untreated CCs and 10% CCs liquor against 400 total U of xylanase and 38 total U of β-xylosidase in xylan. These results indicate that the treatment of agroindustrial wastes through autohydrolysis can be a viable strategy in the production of high levels of xylanolytic enzymes.
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http://dx.doi.org/10.1007/s00449-012-0705-5DOI Listing
September 2012

Development and characterization of an environmentally friendly process sequence (autohydrolysis and organosolv) for wheat straw delignification.

Appl Biochem Biotechnol 2011 Jul 28;164(5):629-41. Epub 2011 Jan 28.

IBB-Institute for Biotechnology and Bioengineering, Centre of Biological Engineering, University of Minho, Campus de Gualtar, 4710-057, Braga, Portugal.

The present work describes the delignification of wheat straw through an environmentally friendly process resulting from sequential application of autohydrolysis and organosolv processes. Wheat straw autohydrolysis was performed at 180°C during 30 min with a liquid-solid ratio of 10 (v/w); under these conditions, a solubilization of 44% of the original xylan, with 78% of sugars as xylooligosaccharides of the sum of sugars solubilized in the autohydrolysis liquors generated by the hemicellulose fraction hydrolysis. The corresponding solid fraction enrichment with 63.7% of glucan and 7.55% of residual xylan was treated with a 40% ethanol and 0.1% NaOH aqueous solution at a liquid-solid ratio of 10 (v/w), with the best results obtained at 180°C during 20 min. The highest lignin recovery, measured by acid precipitation of the extracted lignin, was 3.25 g/100 ml. The lignin obtained by precipitation was characterized by FTIR, and the crystallinity indexes from the native cellulose, the cellulose recovered after autohydrolysis, and the cellulose obtained after applying the organosolv process were obtained by X-ray diffraction, returning values of 21.32%, 55.17%, and 53.59%, respectively. Visualization of the fibers was done for all the processing steps using scanning electron microscopy.
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http://dx.doi.org/10.1007/s12010-011-9163-9DOI Listing
July 2011

Effect of chitosan-based coatings on the shelf life of salmon (Salmo salar).

J Agric Food Chem 2010 Nov 11;58(21):11456-62. Epub 2010 Oct 11.

IBB - Institute for Biotechnology and Bioengineering, Centre of Biological Engineering, Universidade do Minho, Campus de Gualtar, 4710-057 Braga, Portugal.

This study aimed at determining the effect of chitosan coating on shelf life extension of salmon ( Salmo salar ) fillets. The success of edible coatings depends highly on their effective wetting capacity of the surfaces on which they are applied. In this context in a first stage the surface properties of salmon fillets and the wetting capacity of the coatings on fish were evaluated. In terms of wettability there were no significant differences (p > 0.05) between the solutions presenting higher values (solutions 1-4); therefore, solution 1 with a spreading coefficient (Ws) of -4.73 mN m(-1), was chosen to be subsequently analyzed and applied on fish fillets. For shelf life analyses the fillets were coated and stored at 0 °C for 18 days. The control and coated fish samples were analyzed periodically for total aerobic plate count (TPC), pH, total volatile base nitrogen (TVB-N), trimethylamine (TMA), thiobarbituric acid (TBA), and ATP breakdown products (K value). The results showed that fish samples coated with chitosan presented a significant reduction (p < 0.05) for pH and K value after 6 days and for TVB, TMA, and TBA values after 9 days of storage, when compared to control samples. In terms of microbial growth, a slower increase in TPC was observed for the coated fish, indicating that chitosan-based coatings were effective in extending for an additional 3 days the shelf life of the salmon. These results demonstrate that chitosan-based coatings may be an alternative for extending the shelf life of salmon fillets during storage at 0 °C.
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http://dx.doi.org/10.1021/jf102366kDOI Listing
November 2010