1,720,957 research outputs found
Clostridial conversion of corn syrup to Acetone-Butanol-Ethanol (ABE) via batch and fed-batch fermentation
No full textCorn syrup - a commercial product derived from saccharification of corn starch - was used to produce acetone-butanol-ethanol (ABE) by Clostridium spp. Screening of commercial Clostridium spp., substrate inhibition tests and fed-batch experiments were carried out to improve ABE production using corn syrup as only carbon source. The screening tests carried out in batch mode using a production media containing 50 g/L corn syrup revealed that C. saccharobutylicum was the best performer in terms of total solvent concentration (12.46 g/L), yield (0.30 g/g) and productivity (0.19 g/L/h) and it was selected for successive experiments. Concentration of corn syrup higher than 50 g/L resulted in no solvents production. Fed-batch fermentation improved ABE production with respect to batch fermentation: the butanol and solvent concentration increased up to 8.70 and 16.68 g/L, respectively. The study demonstrated the feasibility of producing solvents via ABE fermentation using corn syrup as a model substrate of concentrated sugar mixtures
Pretreatment of coffee silverskin with ultrasound and mild alkaline solutions for enhancement of sugar yield
Full text linkThe increasing global energy requirement is shifting the scientific
attention from fossil to bio-based resources to produce energy
and chemicals. Lignocellulose is the most abundant natural and
renewable resource on Earth. A considerable amount of such material
is generated as waste through agricultural practices mainly
from various agro-industries. Agriculture food processing wastes
(AFWs) are potential feedstock for biorefinery processes being economic
and eco-friendly. Coffee silverskin (CSS) is anAFWsproduced
during the coffee beans roasting process. These vegetable residues
are recalcitrant to enzymatic and microbial attacks, limiting their
use for biorefinery applications. Pretreatment delignification methods
are required to facilitate the enzymatic hydrolysis of AFWs
aimed at the recovery of monomeric fermentable sugars from these
residues. The aim of this study was to develop a pretreatment
process by using ultrasound and mild alkaline solutions for the
effective separation of lignin and cellulose to improve the sugar
yield from CSS. The effects of sonication time, biomass loading,
sodium hydroxide concentration and residence time in autoclave,
were studied using Response Surface Methodology (RSM). A maximum
reducing sugar yield of 0.6 gsugar/gtotal sugar in pretreated biomass
was obtained with 5min sonication, 11% w/v biomass loading,
5% w/v NaOH and 75 min autoclave. Analysis of liquid after pretreatment
revealed that fermentation inhibitors like furfural, HMF,
ferulic and p-coumaric acid were absent or present in non-toxic
concentrations for various Clostridium sp. Moreover, a phenolic
content of 25.3 mgGAE/graw CSS was found. Changes of biomass
structural properties after pretreatment were highlighted by SEM
and XRD analysis
Ultrasound-assisted dilute acid pretreatment of coffee silverskin for biorefinery applications
No full textCoffee silverskin (CSS) is an agro-food processing waste (AFW) largely produced in roasting factories at almost constant rate over the year. The CSS can be used as a source of fermentable sugars within a biorefinery approach for its exploitation. Pretreatment process and enzymatic hydrolysis are required to efficiently recovery monomeric fermentable sugars from AFWs such as CSS. Current research is focused on the selection of novel processes for biomass pretreatments able to provide effective lignin removal, to minimize the production of by-products that may inhibit the fermentation of the produced sugars, and to be cost saving with respect to conventional pretreatments. The aim of the present study was to investigate the effect of the ultrasound (US) assisted dilute acid pretreatment on the effective separation of lignin and polysaccharides of CSS. The effects of two operating conditions - biomass loading and sulphuric acid concentration - were studied to assess their effects on the sugar yields after enzymatic hydrolysis. The production of typical species that may inhibit the fermentation of the hydrolysate was monitored. Inhibitors like furfural, 5-hydroxymethyl furfural (HMF), ferulic and p-coumaric acid were present at concentrations lower than 1 mg/L after enzymatic hydrolysis of the pretreated CSS. As a result, the hydrolysate of US dilute acid pretreated CSS may be used for fermentation without detoxification ste
Food grade pilot scale strategy for non-thermal extraction and recovery of phenolic compounds from orange peels
Full text linkThe orange peels (OP) derived from orange juice factories consist of several polymers and molecules that could
be recovered using a biorefinery approach. This study presents a pilot-scale strategy for the extraction and recovery
of phenolic compounds from OP, aiming to demonstrate a sustainable, non-thermal process that operates
without the use of solvents and complies with food-grade standards. The extraction process was conducted in a
food-grade manner on a 1000 L scale, starting with the enzymatic hydrolysis of pectin in the biomass, followed
by ultrasound-assisted extraction (UAE) at 54 W/gslurry and 20 ◦C. Solid/liquid separation via decanter centrifuge
allowed to recover the solution containing the phenolic compounds, that was further purified via sequential
cross-flow microfiltration (MF), ultrafiltration (UF) and nanofiltration (NF). The final product was analysed by
HPLC-ESI-TOF-MS, revealing an interesting phenolic profile with several potential bioactivities and a total
polyphenol content (TPC) of 3.3 g/L. The food-grade analysis confirmed the potential application of the final
product in food-related processes, such as food packaging or fortification. This work highlights a scalable and
environmentally friendly method to convert agro-food waste into valuable bioactive compounds, aligning with
green chemistry principles and zero-waste strategies.Bio Base Europe Pilot Plant (Ghent,
Belgium)University of Granada (Granada, Spain) as part of the
SHEALTHY projectEuropean Union’s
Horizon 2020 research and innovation program under grant agreement
No 81793
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Optimization of pretreatment/hydrolysis processes of agro-food wastes to support biorefinery developments
Full text linkThe study carried out during the present Ph.D. program aimed at investigating the use of agro-food processing wastes (AFWs) to produce fermentable sugars and/or value-added bioproducts according to the biorefinery approach. The work was carried out at the Dipartimento di Ingegneria Chimica, dei Materiale e della Produzione Industriale of the Università degli Studi di Napoli ‘Federico II’. The activities were focused on the release of sugars (pentoses and hexoses) from the AFWs investigated through different pretreatment processes, followed by enzymatic hydrolysis step. The fermentation of the produced sugar solutions was also carried out to produce biobutanol and succinic acid. Two AFWs were investigated: coffee silverskin and apple pomace.
Coffee silverskin as feedstock for biorefinery applications:
Coffee silverskin (CSS) are the residual thin teguments wrapping and protecting the external layer of green coffee beans. It is produced in large amount during the roasting phase of green coffee beans. It is mainly composed of carbohydrates (40% w/w) and lignin (30% w/w). The study of CSS was aimed at investigating the pretreatment, enzymatic hydrolysis and fermentation of this residue. A combination of mild alkaline solution and ultrasound (US) was applied to pretreat CSS. Biomass loading, sonication time, alkali concentration, residence time in autoclave were the parameters investigated and analysed according to a response surface methodology approach. The process was characterized in terms of sugar yield after the enzymatic hydrolysis of pretreated CSS. Alkali concentration and residence time in autoclave were the most significant parameters affecting the pretreatment process according to the statistical analysis. Under optimal operating conditions the maximum sugar yield was of 60% g/g. Moreover, the phenolic content assessed in the supernatant after CSS pretreatment was (25 mgGAE/graw_CSS) larger than that reported in the literature for similar works on CSS.
The study about enzymatic hydrolysis of alkali-pretreated CSS highlighted that both biomass loading and cellulolytic enzymes loading affect sugars release. A sugar yield higher than 90% g/g was obtained with 10% w/v biomass loading and 80 FPU/gcellulose enzyme loading. The rich-in-sugars hydrolysate obtained after pretreatment and enzymatic hydrolysis of CSS was supplemented with some other nutrients and used as media for fermentation of C. acetobutylicum (ABE production) and A. succinogenes (succinic acid production). Concentration of 3.2 g/L ABE and 20.8 g/L succinic acid was obtained, at the end of each fermentation, respectively.
With the proposed process (pretreatment, hydrolysis and fermentation), we were able to obtain fermentable sugars, lignin, solvents (ABE fermentation) and biochemicals (phenolic compounds and succinic acid) from CSS, stressing the potentialities of this residue to be used in biorefinery processes.
Apple pomace as feedstock for biorefinery applications:
Apple is a fruit widely produced and eaten all over the world. In Italy, more than 2.5 million tons of apple are produced every year. Worldwide, 20 % of fresh apple is processed into value added products: apple juice concentrate (65%), apple cider, wine, vermouth, purees, jams and dried apple products. The main residue of these processes is the apple pomace. This residue accounts for 25-35% of the dry mass of apple. The apple pomace is a good lignocellulosic candidate to be used in a biorefinery process, and it was already used as feedstock for production of butanol, ethanol and crude protein (or enzymes), citric acid, microbial colours, bio-hydrogen.
Pretreatment of apple pomace was carried out by means of the ligninolytic enzyme “laccase”. The aim of this study was to investigate the possibility to carry out biological pretreatment and hydrolysis of apple pomace in a bubble column bioreactor. The proposed pretreatment/hydrolysis system aimed at the optimization of some parameters affecting the process in terms of amount of sugars released during the whole process. The enzymatic delignification was carried out using fungal laccases from Pleurotus ostreatus. Then the cellulose in the pretreated biomass was hydrolysed using Cellic CTec2® (Novozymes). The optimization of enzymatic pretreatment/hydrolysis process indicated that all the parameters investigated (biomass loading, laccase loading, gas (air) flow rate, cellulase loading) affect the performances of the process in terms of biomass composition and sugars release during the enzymatic hydrolysis. 15 %w/v biomass loading, 60 nL/h air flow rate, 30 U/gbiomass laccase concentration, and 20 FPU/gcellulose cellulase concentration were the optimal conditions for the sequential enzymatic pretreatment and hydrolysis process in the bubble column. All the experiments were carried out in a lab-scale bubble column. Under the operating conditions investigated, a maximum sugar yield of 0.34 gsugars/graw biomass was obtained, corresponding to 61% (gsugars/gsugars available) of the theoretical sugar yield obtainable from raw apple pomace.
The high amount of sugars obtained, make AP one of the main feedstocks to be used in fermentative processes to produce solvents and biochemicals. Moreover, a solid residue of lignin that can be recovered and reused was obtained at the end of the process.
ABE fermentation at University of Western Ontario (UWO) (Canada):
The reasearch activity was focused on the ABE fermentation of an industrial product derived from corn: corn syrup. The objectives were: i) to screen four Clostridium species to identify the microorganism characterized by the best fermentative performance in terms of solvents production, yield and productivity; ii) to study the effects of substrate/product concentration on fermentation process (substrate/product inhibition effects); iii) to increase solvents production by means of a fed-batch process.
The final aim of this project was to investigate the possibility of using corn syrup to produce solvents through ABE fermentation. The details regarding this activity are reported in the section Appendix.
Regarding the main topic of my Ph.D. project, the work carried out at UWO have had a double purpose: 1) to improve my skills in anaerobic fermentative processes carried out by different Clostridium species in accordance to the final aim of the European project Waste2Fuels that is the bio-butanol production starting from agro-industrial residues; 2) to compare the fermentative performances of Clostridium spp. on agro-industrial products with various degrees of difficulty to ferment (in particular corn syrup and coffee silverskin)
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