•Cruciferous vegetables as fermented products has been used since ancient times.•During fermentation of cruciferous vegetables complete fermentation of glucosinolates occur.•Fermentation decrease the ...content of complex polyphenols, while increase the content of polyphenols in free form.•Carotenoid content decrease during fermentation of cruciferous vegetables.
Cruciferous vegetables are considered functional foods because of their content of health-related compounds. They are grown and consumed in various cultures around the world. Fermentation as a preservation method for cruciferous vegetables has been used since ancient times. This process results in fermented products that have a unique flavour and odour, high bioactivity, and a distinctly different phytochemical profile than raw vegetables. In this mini review, we summarize data on changes in phytochemical content during lactic-acid fermentation of various cruciferous vegetables. The main focus was on the changes in the group of glucosinolates, polyphenols and carotenoids.
Competition among renewable energy sources in today's market is growing rapidly. Renewables have grown to the point where they are taking significant material market share from coal, gas, and ...uranium. Recently, biodiesel production has been intensified by lipase-catalyzed transesterification performed in microsystems. Another challenge in biodiesel production is the purification of the biodiesel. Common purification methods are usually more energy and time consuming than the biodiesel production itself.
In this work, an integrated biodiesel production process composed of lipase-catalyzed transesterification of sunflower oil and product purification was performed in microreactor and microseparator units connected in series. Glycerol, the by-product of the transesterification process, was removed from the reaction mixture by two different separation methods, deep eutectic solvent extraction and membrane separation. Different integrated setups were developed and evaluated in terms of FAME yield and purity. The most promising integrated process was found to be the one combining 2-inlets feeding strategy for biodiesel production in a microreactor with a microseparator connected in series, in which a choline chloride-glycerol deep eutectic solvent was used. In this integrated system, a FAME yield of 94% and a glycerol content below 0.02% (w/w) were achieved for the residence time of 20 min.
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The 3,5-dinitrosalicylic acid (DNS) assay has been used for many years mainly to determine the enzymatic activity of xylanase. The assay is based on the detection of reduced sugars. Although the ...method is widely used, several recent studies have questioned the accuracy of the method. They mainly focused on the detection of side reactions that could lead to a false positive result of the assay. In this study, the basic components of the DNS assay such as buffer preparation, substrate source and concentration, incubation time, reagent preparation, and activity calculation were re-evaluated. Potential problems were detected and a new assay procedure was proposed. Compared to literature data, the new assay is shorter because it avoids the generation of a calibration curve and takes into account the enzyme and substrate amount when calculating enzyme activity, which is neglected in current assays.
One of the approaches widely used today to intensify processes is their miniaturization. Small, compact, portable devices that can be used directly in the field will become popular in the near ...future. The use of microstructured devices is becoming more widespread in diagnostics, analytics, and production, so there is no doubt that the same approach is being applied to energy production. The question is whether it is possible to create an energy production system that has all the external characteristics of a miniaturized device but is sustainable, durable, environmentally friendly, based on renewable sources, and cost-effective. The first challenge is to choose a production route, an energy source that has the required characteristics, and then to adapt this production on a microscale. Among the different energy sources, biohydrogen meets most of the requirements. The carbon emissions of biohydrogen are much lower, and its production is less energy-intensive than conventional hydrogen production. Moreover, it can be produced from renewable energy sources. The challenge today is to make this process sustainable due to the low substrate conversion, production rate, and yield. Microfluidic systems are one of the technologies that could address the above shortcomings of the current biohydrogen production processes. The combination of microdevices and biohydrogen production opens up new possibilities for energy production. Although this area of research is growing, the focus of this review is on the possibility of using microfluidics for biohydrogen production.
Despite the fact that microreactors have been present for more than 40 years now and that their potential has been extensively exploited in chemical synthesis, analytics and screening, to date very ...few biocatalytic processes have been explored in microreactors. It is claimed that enzymatic microreactor technology is exactly in the same place where chemical microreactors were 15 years ago. However, general opinion is that the efforts devoted to the research of micro-enzymatic reactors will inaugurate a new breakthrough in bio-based processing. The aim of this review is to explore the synergy between microtechnology, mainly microreactors, and biotechnology, and to assess its potential, opportunities, challenges and future application in biotechnology.Key words: microreactor, biotechnology, enzyme, immobilization, biocatalysis
Emulsions are traditionally prepared with the application of high shear forces generated by the use of static mixers, homogenisers, or ultrasound. The resulting emulsions are sensitive to change of ...process conditions. The application of high forces and temperatures can significantly affect the constituents of the emulsions and their final stability. Microfluidic technology seems to be a very efficient alternative to classic emulsification methods. The dimensions of microdevices in combination with continuous processes offer a great advantage over classic batch emulsification processes carried out on a larger scale. The small dimensions of the microdevices allow easy transport of equipment, better control and safety of the process, and intensified mass and energy transfer. The mixing time in microdevices is reduced to a few milliseconds because the molecules in the microchannels have a short diffusion path. In this paper, an overview of emulsification processes, the advantages of use of microfluidics in emulsification, and future perspectives of microemulsification are presented.
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•Seven different DESs and water were used for glycerol extraction from biodiesel.•Extractions were performed using microextractors of different size.•Mathematical model of the ...extraction process was developed and validated.•For residence time of 13.61 s 99% of glycerol was removed by using DES.
Nowadays, the production of biodiesel by transesterification is a common process. On the other hand, once the biodiesel is produced, the purification of crude biodiesel to the extent that satisfies international standard norms still presents a significant challenge. One of the biggest challenges is the removal of glycerol. In this paper, the total of seven different deep eutectic solvents (DESs) based on a mixture of choline chloride and ethylene glycol or a mixture of choline chloride and glycerol were prepared and applied for biodiesel purification, using three microextractors of different sizes. The obtained results were compared with the results of biodiesel purification by wet washing in the same microextractor type. For the residence time of only 13.61 s, by using a ChCl:Gly1:2.5 DES, glycerol was almost completely removed from the biodiesel. So, the obtained result clearly justifies the application of DESs in microextractors for glycerol removal during biodiesel purification.
U organskoj kemiji sve se više pažnje posvećuje sintezi u mikro- i mezo- protočnim sustavima (engl. flow chemistry), koja ima brojne prednosti nad šaržnom sintezom. Glavne prednosti provedbe organske ...sinteze u takvim protočnim reaktorima su veća učinkovitost, ekološka prihvatljivost i sigurnost. Unatoč tome sinteza u protočnim sustavima ne može se primjenjivati kao univerzalni pristup za sve probleme koji mogu zateći organske sintetske kemičare te prije provedbe odabranih reakcija treba razmotriti isplativost s obzirom na šaržnu sintezu. Sigurnosti i ekološkoj prihvatljivosti sinteza u protočnim reaktorima značajno doprinosi upotreba malog volumena kemikalija i otapala budući da se reakcije provode u mikro- ili mezo- reaktorima napravljenima u pravilu od inertnih materijala. Zbog brojnih prednosti, organske reakcije u protočnim sustavima predmet su kontinuiranog istraživanja, pri čemu se uvjeti provedbe reakcija optimiraju u svrhu povećanja učinkovitosti i sigurnosti procesa te njegova uvećanja.
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The most common reaction for biodiesel production is catalysed by acid, base or enzyme catalysts. When transesterification is completed, the reaction mixture contains various impurities such as soap, ...catalyst, free glycerol and alcohol that have to be removed to meet the biodiesel international standard specifications. In this work, biodiesel was produced by lipase catalysed transesterification from edible sunflower oil and methanol as substrates. The purification of crude biodiesel was carried out by decantation followed by ultrafiltration membrane technology. Four different membranes, polyethersulfone, polyacrylonitrile, polypropylene and regenerated cellulose were selected and used for biodiesel ultrafiltration. Based on permeate flux and glycerol content in the permeate membrane performance was evaluated. The obtained results showed that two out of four tested membranes have potential for biodiesel purification. Polyacrylonitrile membrane showed the best performance resulting in lowest glycerol content in permeate (0.006% (w/w)). Additionally, polyacrylonitrile membrane was successfully reused six times without significant loss of performance. Furthermore, the membrane blocking mechanisms were analysed for all membranes by Hermina’s model. Consequently, complete cake layer formation was identified as the most dominant blocking effect.
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•Biodiesel produced by lipase catalysed transesterification was purified by ultrafiltration.•Four different ultrafiltration membranes were tested and compared.•Polyacrylonitrile membrane showed the best performance.•The most dominant blocking effect according Hermina’s model was complete cake layer formation.
The lipase production process by Thermomyces lanuginosus solid-state cultivation on hull-less pumpkin oil pomace was studied. A reduced quadratic model of lipase production was proposed based on the ...optimization of five independent variables followed by a model validation with 95% accuracy. Maximum lipase production was obtained after a process duration of 2 days with high volumetric and specific activity. The enzyme activity of 391 U gdb –1 proves that the developed process is highly efficient. Partial purification of the crude enzymatic extracts was investigated, and a highly concentrated lipase liquid preparation with a volumetric activity of 422 U cm–3 was achieved. The sustainability of the process was confirmed by a snapshot assessment using the green chemistry matrix of the E-factor and the process mass intensity, quoting on the mass efficiency. The new lipase process was in the range of the best white biotechnology processes, as per green chemistry metrics ranking.
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