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21.
González-Sáiz JM Esteban-Díez I Sánchez-Gallardo C Pizarro C 《Analytical and bioanalytical chemistry》2008,391(8):2937-2947
Wastes and by-products of the onion-processing industry pose an increasing disposal and environmental problem and represent
a loss of valuable sources of nutrients. The present study focused on the production of vinegar from worthless onions as a
potential valorisation route which could provide a viable solution to multiple disposal and environmental problems, simultaneously
offering the possibility of converting waste materials into a useful food-grade product and of exploiting the unique properties
and health benefits of onions. This study deals specifically with the second and definitive step of the onion vinegar production
process: the efficient production of vinegar from onion waste by transforming onion ethanol, previously produced by alcoholic
fermentation, into acetic acid via acetic fermentation. Near-infrared spectroscopy (NIRS), coupled with multivariate calibration
methods, has been used to monitor the concentrations of both substrates and products in acetic fermentation. Separate partial
least squares (PLS) regression models, correlating NIR spectral data of fermentation samples with each kinetic parameter studied,
were developed. Wavelength selection was also performed applying the iterative predictor weighting–PLS (IPW-PLS) method in
order to only consider significant spectral features in each model development to improve the quality of the final models
constructed. Biomass, substrate (ethanol) and product (acetic acid) concentration were predicted in the acetic fermentation
of onion alcohol with high accuracy using IPW-PLS models with a root-mean-square error of the residuals in external prediction
(RMSEP) lower than 2.5% for both ethanol and acetic acid, and an RMSEP of 6.1% for total biomass concentration (a very satisfactory
result considering the relatively low precision and accuracy associated with the reference method used for determining the
latter). Thus, the simple and reliable calibration models proposed in this study suggest that they could be implemented in
routine applications to monitor and predict the key species involved in the acetic fermentation of onion alcohol, allowing
the onion vinegar production process to be controlled in real time. 相似文献
22.
The purpose of the study was to evaluate the impact of the Saccharomyces cerevisiae and S. kudriavzevii mixed culture on the fermentation, chemical and aromatic composition of semi-sweet white wines. The variables tested in the experiment were the initial ratio of yeast in mixed cultures and the time of inoculation of the S. kudriavzevii co-culture. The addition of S. kudriavzevii to the inoculum did not significantly change the chemical composition of the wines obtained. No reduction in ethanol yield was found in mixed culture fermented wines; however, in some variants of the experiment, the ethanol content was higher. The mixed cultures of S. cerevisiae and S. kudriavzevii increased the level of volatile compounds in white grape wines. Wines fermented with the co-culture of S. kudriavzevii were characterized by a more diversified ester profile. The mixed cultures of S. cerevisiae and S. kudriavzevii raised the levels of terpenes in white wines. The most promising results were obtained for mixed culture variants, in which S. kudriavzevii was sequentially inoculated on the sixth day of fermentation. 相似文献
23.
Macchione MM Merheb CW Gomes E da Silva R 《Applied biochemistry and biotechnology》2008,146(1-3):223-230
A comparative study was carried out to evaluate protease production in solid-state fermentation (SSF) and submerged fermentation
(SmF) by nine different thermophilic fungi – Thermoascus aurantiacus Miehe, Thermomyces lanuginosus, T. lanuginosus TO.03, Aspergillus flavus 1.2, Aspergillus sp. 13.33, Aspergillus sp. 13.34, Aspergillus sp. 13.35, Rhizomucor pusillus 13.36 and Rhizomucor sp. 13.37 – using substrates containing proteins to induce enzyme secretion. Soybean extract (soybean milk), soybean flour,
milk powder, rice, and wheat bran were tested. The most satisfactory results were obtained when using wheat bran in SSF. The
fungi that stood out in SSF were T. lanuginosus, T. lanuginosus TO.03, Aspergillus sp. 13.34, Aspergillus sp. 13.35, and Rhizomucor sp. 13.37, and those in SmF were T. aurantiacus, T. lanuginosus TO.03, and 13.37. In both fermentation systems, A. flavus 1.2 and R. pusillus 13.36 presented the lowest levels of proteolytic activity. 相似文献
24.
Pablo Giménez-Gómez Manuel Gutiérrez-Capitán Fina Capdevila Anna Puig-Pujol César Fernández-Sánchez Cecilia Jiménez-Jorquera 《Analytica chimica acta》2016
l-lactic acid is monitored during malolactic fermentation process of wine and its evolution is strongly related with the quality of the final product. The analysis of l-lactic acid is carried out off-line in a laboratory. Therefore, there is a clear demand for analytical tools that enabled real-time monitoring of this process in field and biosensors have positioned as a feasible alternative in this regard. The development of an amperometric biosensor for l-lactate determination showing long-term stability is reported in this work. The biosensor architecture includes a thin-film gold electrochemical transducer selectively modified with an enzymatic membrane, based on a three-dimensional matrix of polypyrrole (PPy) entrapping lactate oxidase (LOX) and horseradish peroxidase (HRP) enzymes. The experimental conditions of the biosensor fabrication regarding the pyrrole polymerization and the enzymes entrapment are optimized. The biosensor response to l-lactate is linear in a concentration range of 1 × 10−6–1 × 10−4 M, with a detection limit of 5.2 × 10−7 M and a sensitivity of – (13500 ± 600) μA M−1 cm−2. The biosensor shows an excellent working stability, retaining more than 90% of its original sensitivity after 40 days. This is the determining factor that allowed for the application of this biosensor to monitor the malolactic fermentation of three red wines, showing a good agreement with the standard colorimetric method. 相似文献
25.
26.
Anodic electrocatalyst plays the co re role in direct alcohol fuel cells(DAFCs),while traditional Pt-catalysts suffer from limited catalytic activity,high over potential and severe CO poisoning.Herein,by selectively depositing Rh atoms on the defective-sites of Pt nanowires(NWs),we developed a new Pt@Rh NW electrocatalyst that exhibited enhanced electrocatalytic performance for both methanol oxidation(MOR)and ethanol oxidation(EOR).Both cyclic voltammetry(CV) and in-situ infrared spectroscopy re... 相似文献
27.
The volumetric productivity of many fermentations is productlimited.In situ removal of these products with liquid organic extractants is limited by either a low product distribution coefficient or
toxicity of the extractant. This paper presents results from studies using mixed extractants, namely mixtures of toxic extractants
that have high distribution coefficients for the product and nontoxic extractants that have low distribution coefficients.
The production of butanol byClostridium acetobutylicum was chosen as a model system for these studies. The mechanisms of toxicity of mixed extractants and the observed responses
to their presence are discussed. 相似文献
28.
Escobar Jose M. Rane Kishore D. Cheryan Munir 《Applied biochemistry and biotechnology》2001,91(1-9):283-296
Pilot plant trials were conducted in a corn wet mill with a 7000-L membrane recycle bioreactor (MRB) that integrated ceramic
microfiltration membranes in a semi-closed loop configuration with a stirred-tank reactor. Residence times of 7.5–10 h with
ethanol outputs of 10–11.5% (v/v) were obtained when the cell concentration was 60–100 g/L drywt of yeast, equivalent to about
109−1010 cells/mL. The performance of the membrane was dependent on the startup mode and pressure management techniques. A steady
flux of 70 L/(m2·h) could be maintained for several days before cleaning was necessary. The benefits of the MRB include better productivity;
a clear productstream containing no particulates or yeast cells, which should improve subsequent stripping and distillation
operations; and substantially reduced stillage handling. The capital cost of the MRB is $21–$34/(m3·yr) ($0.08–$0.13/[gal·yr]) of ethanol capacity. Operating cost, including depreciation, energy, membrane replacement, maintenance,
labor, and cleaning, is $4.5–9/m3 ($0.017–$0.034/gal) of ethanol. 相似文献
29.
Lemos Judith L. S. Fontes Maria C. de A. Pereira Nei 《Applied biochemistry and biotechnology》2001,91(1-9):681-689
The use of purified xylan as a substrate for bioconversion into xylanases increases the cost of enzyme production. Consequently,
there have been attempts to develop a bioprocess to produce such enzymes using different lignocellulosic residues. Filamentous
fungi have been widely used to produce hydrolytic enzymes for industrial applications, including xylanases, whose levels in
fungi are generally much higher than those in yeast and bacteria. Considering the industrial importance of xylanases, the
present study evaluated the use of milled sugarcane bagasse, without any pretreatment, as a carbon source. Also, the effect
of different nitrogen sources and the C∶N ratio on xylanase production by Aspergillus awamori were investigated, in experiments carried out in solid-state fermentation. High extracellular xylanolytic activity was observed
on cultivation of A. awamori on milled sugarcane bagasse and organic nitrogen sources (45 IU/mL for endoxylanase and 3.5 IU/mL for β-xylosidase). Endoxylanase
and β-xylosidase activities were higher when sodium nitrate was used as the nitrogen source, when compared with peptone, urea,
and ammonium sulfate at the optimized C∶N ratio of 10∶1. The use of yeast extract as a supplement to the these nitrogen sources
resulted in considerable improvementin the production of xylanases, showing the importance of this organic nitrogen source
on A. awamori metabolism. 相似文献
30.
《Physics and Chemistry of Liquids》2012,50(6):607-621
In this article, isobaric vapor–liquid equilibria for the ternary mixture of ethanol?+?benzene?+?cyclohexane was experimentally investigated at atmospheric pressure. Vapor–liquid equilibria data for ethanol?+?benzene?+?cyclohexane at 101.3?kPa were obtained with a Othmer-type ebulliometer. Data were tested and considered thermodynamically consistent. The experimental results showed that this ternary mixture is completely miscible and exhibits three binary homogeneous azeotropes and a ternary minimum azeotrope at the studied conditions. Satisfactory results were obtained for correlation of equilibrium compositions with UNIQUAC activity coefficients model and also for prediction with UNIFAC method. In both cases, low root mean square deviations of vapor mole fraction and temperature were calculated. The capability of ethanol as modified distillation agent at atmospheric condition is discussed in terms of the thermodynamic topological analysis. However, owing to the complex topology of the ternary mixture it leads to a distillation scheme with three columns and difficult operation and thus, ethanol is not recommended as a separating agent for benzene?+?cyclohexane azeotrope. 相似文献