Effect of Water Content on the Thermal Inactivation Kinetics of Horseradish Peroxidase Freeze-Dried from Alkaline pH

The thermal inactivation of horseradish peroxidase freeze-dried from solutions of different pH (8, 10 and 11.5, measured at 25 C) and equilibrated to different water contents was studied in the temperature range from 110 to 150 C. The water contents studied (0.0, 1.4, 16.2 and 25.6 g water per 100 g of dry enzyme) corresponded to water activities of 0.0, 0.11, 0.76 and 0.88 at 4 C. The kinetics were well described by a double exponential model. The enzyme was generally more stable the lower the pH of the original solution, and for all pH values, the maximum stability was obtained at 1.4 g water/100 g dry enzyme. Values of z were generally independent of water content and of the pH of the original solution, and in the range of 15–25 °C, usually found in neutral conditions, with the exception of the enzyme freeze dried from pH 11.5 and equilibrated with phosphorus pentoxide, where a z-value of the stable fraction close to 10 C was found

Characterization of Plum Procyanidins by Thiolytic Depolymerization

The phenolic compounds of ?Green Gage? (GG) plums (Prunus domestica L.), ?Rainha Cla?udia Verde?, from a ?protected designation of origin? (PDO), in Portugal, were quantified in both flesh and skin tissues of plums collected in two different orchards (GG-V and GG-C). Analyzes of phenolic compounds were also performed on another GG European plum obtained in France (GG-F) and two other French plums, ?Mirabelle? (M) and ?Golden Japan? (GJ). Thiolysis was used for the first time in the analysis of plum phenolic compounds. This methodology showed that the flesh and skin contain a large proportion of flavan-3-ols, which account, respectively, for 92 and 85% in GJ, 61 and 44% in GG-V, 62 and 48% in GG-C, 54 and 27% in M, and 45 and 37% in GG-F. Terminal units of procyanidins observed in plums are mainly (+)-catechin (54?77% of all terminal units in flesh and 57?81% in skin). The GJ plums showed a phenolic composition different from all of the others, with a lower content of chlorogenic acid isomers and the presence of A-type procyanidins as dimers and terminal residues of polymerized forms. The average degree of polymerization (DPn) of plum procyanidins was higher in the flesh (5?9 units) than in the skin (4?6 units). Procyanidin B7 was observed in the flesh of all GG plums and in the skin of the Portuguese ones. Principal component analysis of the phenolic composition of the flesh and skin of these plums obtained after thiolysis allowed their distinction according to the variety and origin, opening the possibility of the use of phenolic composition for variety/origin identification

A kinetic study on the effect of hyperbaric storage on the development of Maillard reaction in glucose-glycine model systems

The effect of pressure (0.1, 15, 50 and 100 MPa) and temperature (43, 53, 63 °C) on the formation rate (k) of Maillard α-dicarbonyls (absorbance at 294) and melanoidins (absorbance at 420 nm), was studied during hyperbaric storage (HS) of glucose-glycine model solutions (pH 6). While increasing storage temperature increased k values according to the Arrhenius equation (Ea ~ 85 kJ mol−1), increasing pressure decreased reaction rates as predicted by the Eyring model (Va ~ 11 mL mol−1). Pressure did not affect reaction temperature sensitivity, indicating no significant mechanism changes under hyperbaric conditions. A combined model predicting the effect of concomitant changes of temperature and pressure on Maillard reaction rate was implemented and validated within and outside (20–25 °C, 20–200 MPa) its building range. Results indicate HS to limit Maillard browning in food, with possible practical applications, and the potential to develop predictive models based on temperature-accelerated HS trials. Industrial relevance: The capability of hyperbaric storage to impair Maillard reaction rate extends the scope of this multi-tasking technology to the prevention of color alterations due to non-enzymatic browning. The latter is expected to be of industrial relevance in the case of perishable foods affected by this phenomenon, such as thermally-treated milk. In these matrices, the technology could concomitantly guarantee microbiological safety, protein functionalization, and Maillard browning impairment

Estratégias de controle de podridões em pós-colheita de melão: uma revisão

Aspectos gerais; Patologia pós-colheita de melão; Aspectos ecológicos e epidemiológicos das doenças em pós-colheita; Maturação de frutos x patologia pós-colheita de frutos; Considerações finais.bitstream/CNPAT-2010/10923/1/Dc-112.pd

Estratégias de controle de podridões em pós-colheita de melão: uma revisão.

Aspectos gerais; patologia pós-colheita de melão; aspectos ecológicos e epidemiológicos das doenças em pós-colheita; maturação de frutos x patologia pós-colheita; manejo integrado de doenças em pós-colheita de frutos.bitstream/CPATSA-2009-09/39310/1/OPB1947.pd

Dispersively detected Pauli Spin-Blockade in a Silicon Nanowire Field-Effect Transistor

We report the dispersive readout of the spin state of a double quantum dot formed at the corner states of a silicon nanowire field-effect transistor. Two face-to-face top-gate electrodes allow us to independently tune the charge occupation of the quantum dot system down to the few-electron limit. We measure the charge stability of the double quantum dot in DC transport as well as dispersively via in-situ gate-based radio frequency reflectometry, where one top-gate electrode is connected to a resonator. The latter removes the need for external charge sensors in quantum computing architectures and provides a compact way to readout the dispersive shift caused by changes in the quantum capacitance during interdot charge transitions. Here, we observe Pauli spin-blockade in the high-frequency response of the circuit at finite magnetic fields between singlet and triplet states. The blockade is lifted at higher magnetic fields when intra-dot triplet states become the ground state configuration. A lineshape analysis of the dispersive phase shift reveals furthermore an intradot valley-orbit splitting $\Delta_{vo}$ of 145 $\mu$eV. Our results open up the possibility to operate compact CMOS technology as a singlet-triplet qubit and make split-gate silicon nanowire architectures an ideal candidate for the study of spin dynamics

Bioactive compounds, pigments, antioxidant activity and antimicrobial activity of yellow prickly pear peels

The main goal of this research was to study the effects of pressure, extraction time and ethanol concentration on antioxidant activity, total phenolics, flavonoids, anthocyanins, carotenoids and betalains compounds extraction from yellow prickly pear peels. A Box-Behnken design and Response Surface Methodology were used to evaluate the effects and estimate the optimum extraction conditions. Antimicrobial activity was evaluated against Escherichia coli and Listeria innocua. Ethanol concentration was the variable that showed the highest effect on extraction yields but high-pressure increased extraction yields between 6% and 17%. Models showed good fitting and adequacy to the experimental data and the high correlation of models indicated that it can be employed to optimise extraction conditions. The experimental and predicted values differed <10% and the extracts inhibited the growth of both bacteria. High-pressure could be a promising extraction process to improve extraction of bioactives from prickly pear peels.info:eu-repo/semantics/publishedVersio

Métodos de controle do etileno na qualidade e conservação pós-colheita de frutas.

Aspectos gerais do meloeiro; Características gerais do melão Cantaloupe; Qualidade; Maturação dos frutos; Etileno; Qualidade pós-colheita de melão por meio do controle de etileno; Permanganato de potássio; 1-MCP; Atmosfera modificada passiva.bitstream/item/33968/1/Dc-111.pd

Pré-termos abaixo das 27 semanas de idade gestacional: desfechos num hospital terciário.

Introduction: Over the last decades, survival of extremely preterm infants improved but there´s still significant morbidity among this group. We pretend to evaluate if specific attitudes/characteristics are associated with higher survival or survival without severe disabilities and elaborate predicting outcome models. Material and Methods: Observational descriptive study, including the 205 liveborn/stillborn infants -gestational age 22w0d-26w6d- born at an Obstetrics Unit or transferred to a Neonatology Unit of a Level III Hospital, from January-2000 to December-2009. We collected variables related to management in the prenatal/neonatal period, neonate performances and psychomotor development (18-24 months). Significant associations between variables/outcomes were identified by chi-square test or t-test; multivariate logistic regression models were used to describe and predict mortality/morbidity. Results: Advanced Gestational Age (GA) (p=0.001), antenatal corticotherapy(p=0.001), cesarean section(p=0.001), inborn delivery(p=0.021) and increased weight(p=0.001) were associated with survival. Absence of Intraventricular Hemorrhage (IVH) grade 3-4(p=0.001) and absence of Periventricular Leukomalacia (PVL) (p=0.005) were associated with survival without severe neurossensorial deficit. According to multivariable models, advanced GA (OR=0.353,CI95% 0.208-0.599), increased weight (OR=0.996,CI95% 0.993-0.999) and antenatal corticotherapy (OR=0.150,CI95% 0.044-0.510) were associated with lower mortality risk. Rupture of membranes less than 12 h duration was associated with higher mortality risk (OR=3.88,CI95% 1.406-10.680). IVH grades 3-4 was associated with higher morbidity risk (OR=16.931,CI95% 2.744-104.452). Mortality and severe morbidity models predicted correctly the outcome in 78.1% and 85.7% of the cases, respectively. Conclusions: Mortality/morbidity models might be valuable tools providing insight in the prediction of the outcome of these neonates and helping parental counseling