monitoring of glucose in beer brewing by a carbon nanotubes based nylon nanofibrous biosensor

This work presents the design, preparation, and characterization of a novel glucose electrochemical biosensor based on the immobilization of glucose oxidase (GOX) into a nylon nanofibrous membrane (NFM) prepared by electrospinning and functionalized with multiwalled carbon nanotubes (CNT). A disc of such GOX/CNT/NFM membrane (40 μm in thickness) was used for coating the surface of a glassy carbon electrode. The resulting biosensor was characterized by cyclic voltammetry and chronoamperometry, with ferrocene methanol as mediator. The binding of GOX around the CNT/NFM greatly enhances the electron transfer, which results in a biosensor with a current five times higher than without CNT. The potential usefulness of the proposed biosensor was demonstrated with the analysis of glucose in commercial beverages and along the monitoring of the brewing process for making beer, from the mashing to the fermentation steps

radical scavenging activity of lipophilic antioxidants and extra virgin olive oil by isothermal calorimetry

Abstract This work proposes an oxidative stress test based on the measurement of the heat generated during the reaction of AIBN (2,2′-azobis(2-methylpropionitrile)) with lipophilic antioxidants. Without antioxidants, AIBN generates an exothermic peak (induction period = 7.50 h, peak time = 8.55 h, area = 3.6 kJ mol −1 of AIBN, at 50 °C). In the presence of antioxidants, such peak is delayed. The extent of such delay provides a simple and direct estimate of the radical-scavenging activity of the sample. Standard solutions of well-known antioxidants lead to the following ranking (from high to low radical scavenging activity): ethoxyquin >>> (±)-α-tocopherol > butylated hydroxytoluene (BHT) > retinyl acetate, in close agreement with the 2,2-diphenyl- l -picrylhydrazyl (DPPH) assay. The proposed assay was applied to characterize the radical-scavenging activity of five extra-virgin olive oil samples. The results were in good agreement with the total phenol content of each sample (R 2 = 0.975)

Inhibition of lipid autoxidation by vegetable waxes

This study aims to evaluate the effect of vegetable waxes on the kinetics of lipid oxidation of linseed oil. Apple and orange waxes were obtained using supercritical carbon dioxide. The capacity of waxes to inhibit or retard the oxidation of linseed oil was determined by isothermal calorimetry at 298 K. The results show that waxes were able to slow down linseed oil autoxidation, with apple waxes being more active than orange waxes. However, such activity was visible only at relatively high concentrations (>1% of waxes), greatly higher than the concentration used with radical chain breakers like BHT (0.2%). The inhibition activity was explained by considering three different mechanisms: (1) residual polyphenol content in the wax, (2) high termination rate of the radical chain process, and (3) physical hindrance of the oxidation process by change in viscosity. All these mechanisms were possible, although the latter seemed to be the most important. Finally, the importance of waxes in the inhibition of lipid autoxidation was determined by testing their inhibition activity in combination with primary antioxidants. A mixture of waxes with BHA, ethoxyquin and alpha-tocopherol showed a higher rate of inhibition than when present individually. This suggested a strong cooperative radical scavenging activity, whose beneficial effect might pave the way to the formulation of novel functional ingredients.Peer reviewe

Transient changes of volatile organic compounds (VOCs) during dulce de leche preparation by a direct injection mass spectrometer based on proton transfer reaction (PTR-MS)

SummaryThe capacity of a direct injection mass spectrometer based on proton transfer reaction (PTR‐MS) to monitor the transient changes of the volatile organic compounds (VOCs) during dulce de leche production was investigated. We found a correlation between the mass fingerprint and some physio‐chemical properties of the dulce de leche samples. The intensity of the selected mass fragments related to VOCs was positively correlated with the changes of solids content but negatively with that of water activity. Rheological and textural changes were also highly correlated with the intensity observed for several mass fragments. Hence, this relationship could be useful to predict the textural and rheological changes during heating a complex fluid. Although not all the correlations between physical changes and VOCs formation reflected a direct cause–effect relationship, but those results demonstrated the suitability of the PTR‐MS technique to monitor the quality changes even in complex food mixture during thermal processing

Antioxidant efficiency and oxidizability of mayonnaise by oximetry and isothermal calorimetry

: This study aimed to introduce a new method based on isothermal calorimetry (IC) for measuring the autoxidation rate in mayonnaise samples. Mayonnaise samples were prepared by homogenizing an aqueous phase, consisting of vinegar and egg yolk, with various oil phases, including sunflower, corn, extra virgin olive, grape seed, and apple seed oils at 60 °C. The rate of free radical formation (Ri) was controlled by adding AIBN (Ri = 4.4±0.1×10-9 M/s). The autoxidation rate determined by IC was highly correlated with the one measured using the oxygen uptake method (R2 = 0.99). The IC method accurately indicated the antioxidant capacity and rates of both inhibited and uninhibited periods, together with the oxidizability of mayonnaise samples. The mayonnaise made with extra virgin olive oil exhibited the lowest oxidizability, while sunflower oil showed maximum antioxidant efficiency. A significant advantage of the IC method was its ability to simultaneously measure up to 24 samples with minimal effort

On the effectiveness of Randomized Signatures as Reservoir for Learning Rough Dynamics

Many finance, physics, and engineering phenomena are modeled by continuous-time dynamical systems driven by highly irregular (stochastic) inputs. A powerful tool to perform time series analysis in this context is rooted in rough path theory and leverages the so-called Signature Transform. This algorithm enjoys strong theoretical guarantees but is hard to scale to high-dimensional data. In this paper, we study a recently derived random projection variant called Randomized Signature, obtained using the Johnson-Lindenstrauss Lemma. We provide an in-depth experimental evaluation of the effectiveness of the Randomized Signature approach, in an attempt to showcase the advantages of this reservoir to the community. Specifically, we find that this method is preferable to the truncated Signature approach and alternative deep learning techniques in terms of model complexity, training time, accuracy, robustness, and data hungriness.Comment: Accepted for IEEE IJCNN 202

Effect of saffron (Crocus sativus L.) enrichment on antioxidant and sensorial properties of wheat flour pasta

[EN] Saffron, used in cookery as a flavouring and colouring agent, is well-known for its antioxidant and beneficial health properties. In the present work, the effect of saffron addition (0-control, 0.1, 0.2 and 0.4%, w/w) in the formulation of fresh pasta was evaluated on textural, physical-chemical, and sensory properties of the cooked product. Content and retention of the bioactive molecules of saffron (crocins) were evaluated by HPLC along with the corresponding antioxidant activity of enriched pasta. The presence of saffron significantly influenced textural and physical-chemical properties of pasta. Higher saffron concentrations enhanced the antioxidant activity of pasta with the higher values of crocins in samples enriched with 0.4% saffron extract even after 3 min of cooking (4.23-5.06 mg/g db). Sensory analysis showed an increased acceptability of the saffron enriched pasta for all descriptors selected (visual aspect, colour, aroma, taste, chewiness, hardness, gumminess and overall acceptability).Authors are thankful to the Province of Bolzano for financial support (Landesregierung mittels Beschluss Nr. 1472, 07.10.2013) and also the Research Institute for Food Research and Development at the Universitat Politecnica de Valencia (UPV), for laboratory facilities.Armellini, R.; Peinado Pardo, I.; Pittia, P.; Scampicchio, M.; Heredia Gutiérrez, AB.; Andrés Grau, AM. (2018). Effect of saffron (Crocus sativus L.) enrichment on antioxidant and sensorial properties of wheat flour pasta. Food Chemistry. 254:55-63. https://doi.org/10.1016/j.foodchem.2018.01.174S556325

Oxidation of ascorbic acid with hydrogen peroxide: investigation with a reaction calorimeter

The oxidation of ascorbic acid (AA) implies first the formation of dehydro-ascorbic acid (DHA) and, in a second step, a further oxidation that breaks the molecule in smaller mass compounds, like oxalic acid and 1,2-ethandiol-1,2-dicarboxy acid. The overall process is therefore the result of two consecutive steps. The process was investigated in isothermal conditions with a reaction calorimeter at different concentration, pH and temperatures. The instrument used is a chemical process analyser CPA202 developed by ChemiSense\uae and designed to suppress uncontrolled temperature differences between the content of the reactor and its. This means that all the heat exchanged from the reactor to the thermostat bath flows through the heat transducer, which is located between the bottom of the reactor and a Peltier element used as a heat pump. A two consecutive step kinetic model allows fitting the experimental trends, provided that a damping factor, exp(-\uf074\uf02ft), is introduced to account for the delay of heat transfer (about 100 s). Both steps follow a first order kinetics (although other combinations were also considered). Taking into account that the overall thermal effect is exothermic, the reaction enthalpies were assumed both negative, or one positive and the other negative

Selenium biofortification in fragaria 7 ananassa: Implications on strawberry fruits quality, content of bioactive health beneficial compounds and metabolomic profile

Selenium (Se) is an essential nutrient for humans, due to its antioxidant properties, whereas, to date, its essentiality to plants still remains to be demonstrated. Nevertheless, if added to the cultivation substrate, plants growth resulted enhanced. However, the concentration of Se in agricultural soils is very variable, ranging from 0.01 mg kg-1 up to 10 mg kg-1 in seleniferous areas. Therefore several studies have been performed aimed at bio-fortifying crops with Se and the approaches exploited were mainly based on the application of Se fertilizers. The aim of the present research was to assess the biofortification potential of Se in hydroponically grown strawberry fruits and its effects on qualitative parameters and nutraceutical compounds. The supplementation with Se did not negatively affect the growth and the yield of strawberries, and induced an accumulation of Se in fruits. Furthermore, the metabolomic analyses highlighted an increase in flavonoid and polyphenol compounds, which contributes to the organoleptic features and antioxidant capacity of fruits; in addition, an increase in the fruits sweetness also was detected in biofortified strawberries. In conclusion, based on our observations, strawberry plants seem a good target for Se biofortification, thus allowing the increase in the human intake of this essential micronutrient