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

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

A novel cascade approach to extract bioactive compounds from officinal herbs

This research aims to compare a novel cascade extraction method with a conventional solid–liquid extraction method, both assisted by ultrasounds. The cascade extraction method consists of a sequential series of extractions performed with the same hydroalcoholic solvent, which is reused from one herb to the other. In practice, a hydroalcoholic solution is firstly used to extract one botanical herb. The resulting extract is then reused for the extraction of a second herb. The process is repeated as many times as the number of herbs composing the final formulation. The main advantage of this approach is firstly the lower need of solvents compared with the individual extraction procedures, where a fresh solvent is needed on each extraction step. Furthermore, extracts of the two methods (solid liquid vs cascade extraction) were characterized with several antioxidant assays (DPPH, ORAC, and FRAP) and total phenolic content (TPC). The results show that the solid–liquid extraction method achieves similar yields to total phenols and similar TAC in comparison to the extracts obtained by the cascade extraction method. Also, the HPLC analysis of the extracts showed that both methods lead to similar chromatographic profiles either when analyzed by an electrochemical detector (CoulArray) or by a spectrometric diode array detector (DAD). However, our findings support the idea that the cascade extraction method obtains extracts richer of minor peaks, showing a more complex bioactive profile. Such results could be explained considering that the solvent used during the series of cascade extractions was enriched not only by antioxidants but also by plant surfactants, like saponins, which increase the solvent solubility. Overall, this research shows that the cascade extraction method can not only provide officinal herb extracts with similar phenolic yield and antioxidant capacity than conventional solid–liquid extraction but also with a more complex bioactive profile compared to traditional solid–liquid extraction and with a minor consumption of solvents

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

Structured Vegetable Lipids as Ice Cream Fat Source

This research aimed to develop a low-saturated ingredient as substitute of saturated fats by structuring lipids through a simple enzymatic glycerolysis process. To this purpose, peanut oil (10 g) was mixed with glycerol (1:1 molar ratio) and lipase (0.4 g). The glycerolysis reaction was carried out for 16 h at 65°C under constant stirring. The obtained structured lipid was then used as a fat source in a mixture for the production of ice cream. The mixtures obtained with structured and unstructured peanut oil were compared to a classical cream-based mixture in terms of particle size and ?-potential. Afterward, the obtained ice creams were assessed based on their physical properties during melting and textural attributes. Glycerolysis of peanut oil reduced the particle size of the formed mixtures, which later created ice creams with a slower melting rate (0.044 g·min-1) compared to the peanut oil-based formulation (0.77 g·min-1). Similar dripping times were measured for the structured-lipid (60.33 ± 1.2 min) and the cream-based (65.00 ± 1.6 min) ice creams. Moreover, the firmness and consistency of the ice cream made with the structured lipid were not significantly different (p < 0.05) compared to the traditional cream-based product. Overall, the results of the present study clearly indicated that structured lipids could be used as ingredient in ice cream production, paving the way for a partial replacement of saturated fats in food formulations

Comparative analysis of antioxidant activity and capacity in apple varieties: Insights from stopped flow DPPH• kinetics, mass spectrometry and electrochemistry

The aim of this research was to investigate the antioxidant kinetics of different apple varieties, a red-flesh variety (‘R201’), a non-browning (‘Majda’), and a ‘Golden Delicious’. Kinetic approaches for antioxidant activity provide more detailed information than conventional assays by examining both the quantity and velocity of active molecules in their reaction with radicals. In this study, DPPH• stopped flow method was applied to study the antioxidant activity and capacity of the three apples varieties, allowing the determination of the reaction rates. The results show that the antioxidant activity of ‘R201’ was not significantly different from ‘Golden Delicious’. Instead, the activity of the non-browning variety was 20 times higher than the others according to the DPPH• kinetic approach, despite having the lowest phenolic content. To further understand their reactivity, the antioxidant molecules were identified using HPLC-HRMS/MS coupled with a coulometric array detector, which validated the DPPH• kinetics. This analysis also found differences in the phenolic profile of the three varieties, attributed to the enhanced antioxidant activity of ’Majda’ to its high content of ascorbic acid. Overall, the research highlights that the antioxidant behavior of apples primarily depends on the velocity of the antioxidants rather than the amount of phenolic compound

WOOD-UP

The fundamental vision of the WOOD-UP project was to develop existing wood gasification plants in South Tyrol towards a polygenerative use in order to be able to produce not only energy but also high-quality charcoal (biochar) for the improvement of soil fertility and for climate protection. The project, funded by the European Regional Development Fund ERDF 2014–2020, was implemented by the Free University of Bolzano together with the Laimburg Research Centre. Based on the life cycle analysis (LCA) or scenario analysis of the entire production chain of wood gasification, strengths and weaknesses of the existing systems were identified with regard to their impact on the environment. Thanks to the results obtained, a number of suggestions for improvement could be formulated.; Il miglioramento verso un assetto poligenerativo degli attuali impianti altoatesini di gassificazione della biomassa legnosa, dove oltre all’energia si possa produrre biochar di qualità da impiegare in agricoltura come ammendante con effetti positivi sulla fertilità dei suoli e sulla mitigazione dei cambiamenti climatici è la visione che ha sostenuto il progetto WOOD-UP. Il progetto, finanziato con fondi FESR 2014-2020, ha visto la collaborazione tra la Libera Università di Bolzano e il Centro di Sperimentazione Laimburg. L’analisi del ciclo di vita e di scenario dell’intera filiera di gassificazione ha evidenziato elementi di forza e di debolezza dell’attuale filiera in termini di impatti ambientali e ha permesso di avanzare proposte di miglioramento sulla base dei risultati ottenuti dalla sperimentazione. ; Grundlegende Vision des Projektes WOOD-UP war die Entwicklung der bestehenden Holzvergasungsanlagen in Südtirol hin zu einer polygenerativen Nutzung, um neben Energie auch hochwertige Holzkohle (Biochar) zur Verbesserung der Bodenfruchtbarkeit und zum Klimaschutz erzeugen zu können. Das mit Mitteln aus dem Europäischen Fonds für regionale Entwicklung EFRE 2014–2020 finanzierte Projekt wurde von der Freien Universität Bozen gemeinsam mit dem Versuchszentrum Laimburg umgesetzt. Anhand der Lebenszyklusanalyse (LCA) bzw. der Szenarioanalyse der gesamten Produktionskette der Holzvergasung wurden Stärken und Schwächen der bestehenden Systeme hinsichtlich ihrer Auswirkungen auf die Umwelt aufgezeigt. Dank der erzielten Versuchsergebnisse konnte eine Reihe von Verbesserungsvorschlägen formuliert werden