Mickael C. Santos

Effect of the ionic liquid [bmim]Cl and high pressure on the activity of cellulase

The effect of the ionic liquid 1-butyl-3-methylimidazolium chloride ([bmim]Cl) and of high pressure on the activity of cellulase from Aspergillus niger were studied separately and in combination. The enzyme activity decreased with increasing concentrations of [bmim]Cl, reaching 50% the value in aqueous buffer with 20% [bmim]Cl. However, when the enzyme is held in 10% [bmim]Cl and is then assayed in 1% [bmim]Cl, it showed only 8% reduction of activity. These results can be explained by the fact that the activity of the enzyme in [bmim]Cl is linearly correlated with the decrease of the thermodynamic water activity (aw). Under pressure the enzyme activity varied from less 60% (at 200MPa) to equal (at 400 MPa), compared to atmospheric pressure. In 10% [bmim]Cl under pressure, cellulase activity is improved compared to atmospheric pressure, varying from equal (at 600 MPa) to 1.7-fold higher (at 100 MPa). This opens the possibility to improve cellulase activity in ionic liquids, and possibly of other enzymes, by carrying out the reaction under pressure.

Chemical and physical methodologies for the replacement/reduction of sulfur dioxide use during winemaking: review of their potentialities and limitations

Sulfur dioxide (SO2) is probably one of the most versatile and efficient additives used in winemaking due to its antiseptic and antioxidant properties. This compound is also important for minimizing phenolic polymerization rate and color loss during wine aging. However, allergies caused by SO2-derived compounds, namely the sulfites, are becoming more frequent, causing symptoms such as headaches, nausea, gastric irritation, and breathing difficulties in asthma patients. Consequently, the legislated maximum concentration of SO2 allowed in wines has been gradually reduced. For this reason, it is crucial in a competitive global winemaking market strategy, to reduce or even eliminate the use of SO2 as a preservative and to search for new healthier and safe strategies. This work gives an overview of the main methodologies that have been proposed so far and that have potential to be used in winemaking as an alternative to SO2. The addition of compounds such as dimethyl dicarbonate, bacteriocins, phenolic compounds, and lysozyme, and the use of physical methods, namely pulsed electric fields, ultrasound, ultraviolet radiation, and high pressure are discussed and critically evaluated.

Effect of high pressure treatments on the physicochemical properties of a sulphur dioxide-free red wine.

The application of high hydrostatic pressure (HHP) in winemaking for substitution of the use of sulphur dioxide is still at a very early stage of development, since knowledge about the effect on physicochemical and sensorial characteristics of the wine during storage is very scarce. In this work, the evolution of colour, antioxidant activity and total phenolic compounds of SO2-free red wines treated by HHP and aged in bottles was followed for 12 months. The pressurised wines were compared with wine samples prepared with addition of 40 ppm of SO2 and without any of these two treatments. After 12 months, the pressurised wines presented higher values of CIELab parameters (a(*), b(*), and L(*)) and a lower monomeric anthocyanin content (45-61%) when compared to the unpressurised ones. The pressurised wines showed also a better global sensorial assessment, with the pressure treatments imparting aged-like characteristics to the wines. The wine deposits of pressurised wines had higher total phenolic content, namely proanthocyanidins (3- to 10-fold). The results demonstrate that HHP can influence long term red wine physicochemical and sensorial characteristics, hypothesised to be due to an increase of condensation reactions of phenolic compounds, forming compounds with higher degree of polymerisation that became insoluble in wine along storage.

High pressure treatments accelerate changes in volatile composition of sulphur dioxide-free wine during bottle storage

The impact of high hydrostatic pressure (HHP) treatments on volatile composition of sulphur dioxide-free wines during bottle storage was studied. For this purpose, white and red wines were produced without sulphur dioxide (SO2) and, at the end of the alcoholic fermentation, the wines were pressurised at 500 MPa and 425 MPa for 5 min. Wine with 40 ppm of SO2 and a wine without a preservation treatment were used as controls. More than 160 volatile compounds, distributed over 12 chemical groups, were identified in the wines by an advanced gas chromatography technique. The pressurised wines contained a higher content of furans, aldehydes, ketones, and acetals, compared with unpressurised wines after 9 months of storage. The changes in the volatile composition indicate that HHP treatments accelerated the Maillard reaction, and alcohol and fatty acid oxidation, leading to wines with a volatile composition similar to those of faster aged and/or thermally treated wines.

Between fuzzy-PID and PID-conventional controllers: a good choice

The main problem in the synthesis of a control system is its parameter adjustment. Fuzzy logic controllers (FLC) have been proved to be very efficient in controlling complex and difficult-to-model processes. One of the main problems of these fuzzy controllers is that there is no systematic procedure for tuning. So, the necessity of methods for guiding the initial selection of the fuzzy controller parameters is clear. We propose an indirect method of tuning. It consists of describing the FLC like a classical controller from the external point of view. This allows the plant operator to feel comfortable with this regulator because he knows the direct influence between the variation of the FLC tuning parameters and the system response. It also facilitates the selection of some initial values that assure a reasonable behavior for the FLC, that could be improved by the qualitative tuning of these parameters.

Urinary metabolomic profiling of asthmatics can be related to clinical characteristics.

Metabolomics has been increasingly explored to achieve an improved understanding of asthma. In the current observational and exploratory study, the first to have examined the relationship between oxidative stress extension, eosinophilic inflammation, and disease severity in asthmatic patients, metabolomics (using target aliphatic aldehydes and alkanes) was carried out using solid‐phase microextraction (SPME) followed by a comprehensive two‐dimensional gas chromatography coupled to mass spectrometry with a high‐resolution time‐of‐flight analyzer (GC×GC‐ToFMS). We were able to demonstrate that metabolomics can give valuable insights into asthma mechanisms once lipidic peroxidation assessed by urinary metabolomics is related to the clinical characteristics of nonobese asthmatics, such as disease severity, lung function, and eosinophilic inflammation. Nevertheless, considering our sample size, the obtained results require further validation using a much larger sample cohort.

Influence of High Hydrostatic Pressure Technology on Wine Chemical and Sensorial Characteristics: Potentialities and Drawbacks

During last years, scientific research on high hydrostatic pressure (HHP) as a nonthermal processing technology for preservation or aging of wine has increased substantially. HHP between 200 and 500MPa is able to inactivate bacteria and yeasts in red and white wines, suggesting that it may be used for wine preservation. However, these treatments have been shown to promote changes on sensorial and physicochemical characteristics in both red and white wines, not immediately in the first month, but along storage. The changes are observed in wine color, aroma, and taste due mainly to reactions of phenolic compounds, sugars, and proteins. These reactions have been associated with those observed during wine aging, leading to aged-like wine characteristics perceived by sensorial analysis. This chapter will present the influence of HHP technology on wine chemical and sensorial characteristics, criticaly discussing its potentialities and drawbacks. The appropriate use of HHP, based on the scientific knowledge of the reactions occuring in wine promoted by HHP, will allow to exploit this technology for wine production achieving distinct characteristics to address particular market and consumer demands.

Comparison of high pressure treatment with conventional red wine aging processes: impact on phenolic composition

High hydrostatic pressure (HHP) applied to wine in flexible plastic bottles has been studied as an enological practice for red wine aging, due to the oxidative reactions that can be promoted by this technology. To evaluate the effect of HHP on wine phenolic composition, a red wine treated with HHP was compared with different conventional wine aging processes, such as the use of wood and microoxygenation. The wine was pressurized at 500 MPa for 5 min at 20 °C and the same wine was also stored in oak barrels and treated with oak chips with or without microoxygenation. For comparison of the HHP effect, all wines were stored in polyethylene bottles. After 5 months, the monomeric anthocyanins, phenolic acids, and flavonols content of pressurized wines were lower in comparison with the other wine treatments. Nevertheless, pressurized wines showed a similar degree of tannin polymerization, pyranoanthocyanins content, and percentage of prodelphinidins in relation to the wine treated with microoxygenation and oak chips. HHP, possible by promoting a higher diffusion of oxygen into the wine, has the potential to be a novel oenological practice, producing red wines with a polymeric phenolic composition similar to those treated with wood aging processes.