Quality and Acceptability of Microwave and Conventionally Pasteurised Kiwifruit Puree

The development and optimisation of food preservation processes seem to be necessary in order to address consumer expectations related to secure, fresh-like foods. To this end, the sensory, nutritional and functional properties must be maximally retained. In order to contribute to the acquisition of knowledge about the adequacy of microwave processing as a means of preserving fruit-based products, the present study compares the impact of microwave heating with conventional thermal processing. The consumer acceptance of fresh and pasteurised kiwifruit puree was studied as was the content of water, soluble solids and bioactive compounds and the pH, consistency, viscosity, colour coordinates and antioxidant capacity, as well as the effect of the thermal treatment on enzyme and microbial inactivation. As bioactive compounds, the content of vitamins C, A and E and the total flavonoid, phenol and tannin content have been considered. As the obtained results show, not only was microwaved puree preferred by consumers, but it also exhibited a superior maintenance of the nutritive and functional properties of the fruit, smaller colour changes and a content of inactivated enzymes and microorganisms equal to or greater than the conventionally heated sample.     

Blanching effects on chemistry, quality and structure of green beans (cv. Moncayo)

Green beans (cv. Moncayo) were blanched at 65, 70, 75, 80, 85, 90 and 97 °C for 2.5, 5, 10, 20 and 40 min. Pectinesterase (PE) activity was highest in cell-wall-bound extracts of beans blanched at 70 °C/10 min. The lowest water-soluble pectin fraction, the highest EDTA-soluble pectin fraction and the lowest degree of esterification of the EDTA-soluble fraction were all recorded for the same temperature/time combination; these effects can therefore be attributed to PE activity. Chemical changes did not affect initial firmness of the beans, which was practically constant after blanching at 65, 70, 75 and 80 °C. Simple first-order models were adequate to establish softening kinetics for beans blanched at 85, 90 and 97 °C. In this temperature range, Kramer maximum force was the mechanical parameter that best characterised bean softening by blanching. For all temperatures, short-time blanching increased the coloration and total chlorophyll content of the samples with respect to fresh control, thus precluding the use of simple models. In the treated beans, the ascorbic acid content was consistently lower than in the control and decreased continuously with increasing time. Microphotographs showed no appreciable differences in morphology between fresh and blanched beans at 65, 70 and 75 °C, which would explain the similarity of mechanical behaviour in these samples. Blanching at 85, 90 and 97 °C caused loosening and swelling of the cell walls owing to breakdown of the pectic material, which again helps to explain the observed loss of firmness.     

Effect of supplementing ewes’ diet with thyme (Thymus zygis ssp. gracilis) leaves on the lipid oxidation of cooked lamb meat

The aim of this study was to ascertain whether the inclusion of thyme leaves in the diet of pregnant sheep affects the sensorial characteristics and oxidative stability of cooked lamb meat. Thirty-six Segureña sheeps were randomly assigned into three homogeneous groups. One group was fed a basal diet as control, while the diet of the other two groups was modified by substituting 3.75% and 7.5% of the control diet with thyme leaves. TBARS, volatile compounds, and the sensory characteristics of cooked lamb meat were analysed on days 0, 2 and 4. The incorporation of thyme into the animal diet favoured the antioxidant capacity of these cooked lamb meat samples. The cooked meat of lambs from ewes fed thyme leaves showed lower TBARS, hexanal values, rancid odour and rancid flavour scores. No statistically significant differences were detected between the results obtained for the two leaf levels.     

Teaching advanced equations of state in applied thermodynamics courses using open source programs

Many advanced equations of state have been developed in the last decades which fulfill important needs of the industry. However, these equations frequently are not taught in applied thermodynamic courses, in part due to the lack of educational resources for including application exercises. This article presents a set of computer programs for the calculation of phase equilibrium and other thermodynamic properties using different equations of state (classical cubic equations, cubic equations with excess Gibbs energy mixing rules, group contribution equations and SAFT equations). All the programs are open-source and allow for different learning approaches, from application exercises with these equations, to correlation of equation parameters or implementation of modified equations and calculation algorithms for more advanced courses. The programs run in the commercial computing software MATLAB as well as in the free, open-source program Octave. The programs have been designed to be easily reusable using an object-oriented programming methodology, and they may have some applications in research. Authors also present their experiences in the application of the programs in applied thermodynamic courses at a Master‘s level.     

Atmospheric plasma spraying coatings from alumina–titania feedstock comprising bimodal particle size distributions

In this work, Al₂O₃–13 wt% TiO₂ submicron-nanostructured powders were deposited using atmospheric plasma spraying. The feedstocks were obtained by spray drying two starting suspensions of different solids content, prepared by adding nanosized TiO₂ and submicron-sized Al₂O₃ powders to water. The spray-dried granules were heat-treated to reduce their porosity and the powders were fully characterised in both untreated and thermally treated state. Comparison with two commercial feedstocks was carried out. Characterisation allowed a temperature for the thermal treatment to be chosen on the basis of the sprayability of the feedstock and the preservation as much as possible of the submicron-sized structure of the unfired agglomerates.Optimisation of the deposition conditions enabled the reconstituted powders to be successfully deposited, yielding coatings that were well bonded to the substrate. The coating microstructure, characterised by SEM, was mostly formed by a matrix of fully molten particles where the presence of semi-molten feedstock agglomerates was also observed.Moreover, microhardness, toughness, adhesion and tribological behaviours were determined, and the impact of the granule characteristics on these properties was studied. It was found that changing the feedstock characteristics allows controlling the coating quality and properties. In general, good mechanical properties were obtained using a feedstock comprising a binary mixture of submicrometric Al₂O₃ and nanometric TiO₂ particles in the spray-dried powder.     

Effect of the polymer shell in imidazole microencapsulation by solvent evaporation method

In this paper, the microencapsulation of imidazole derivatives (1-methylimidazole and 2-phenylimidazole, 1-MIm and 2-PhIm, respectively) as core materials into polymeric shells has been studied. Imidazoles are used as latent curing agents for epoxy resins with application for example in the manufacturing of electronic devices. Microencapsulation of imidazoles has been carried out by solvent evaporation and different experimental parameters (e.g. type of polymer for the shell) have been analyzed and the final properties of the capsules obtained (particle size, morphology or thermal properties). Characterization has been carried out using differential scanning calorimetry (DSC) and thermal gravimetry analysis (TGA) for the thermal properties and determination of the imidazole content (%) into the capsules, and scanning electron microscopy (SEM) for the morphological characterization. Using infrared spectroscopy (IR), chemical characterization of the capsules has been carried out, confirming the presence of both components imidazole and polymer in the case of the microcapsules prepared with 2-PhIm. The reaction mechanism of the curing process of a standard epoxy resin with the different microencapsulated imidazoles has been also studied. Results have shown that the thermal stability of the capsules and the weight losing rate of the imidazole in the capsules depend on the polymer used for the shell.     

Hydrophilic antioxidants of virgin olive oil. Part 1: Hydrophilic phenols: A key factor for virgin olive oil quality

Virgin olive oil (VOO) consumption is increasing all over the world due to its excellent organoleptic and nutraceutical properties. These beneficial traits stand from a prominent and well‐balanced chemical composition, which is a blend of major (98% of total oil weight) and minor compounds including antioxidants. The main antioxidants are phenolic compounds, which can be divided into lipophilic and hydrophilic phenols. While lipophilic phenols such as tocopherols can be found in other vegetable oils, most hydrophilic phenols in olive oil are exclusive of the Olea europaea species endowing it with a chemotaxonomic interest. This review is focused on VOO antioxidant profile and, particularly, on hydrophilic phenols that are divided into different sub‐families such as phenolic acids and alcohols, hydroxy‐isochromans, flavonoids, secoiridoids, lignans and pigments. Analytical methods for qualitative and/or quantitative determination of these compounds are assessed. The implementation of efficient sample preparation protocols, separation techniques such as liquid chromatography, GC and capillary electrophoresis, as well as detection techniques such as ultraviolet absorption, fluorescence or MS are critical to succeed in the quality of the results. The effects of hydrophilic phenols on increasing VOO stability, its nutraceutical interest and organoleptic properties are also considered.     

A Pd(II) Magnetically Retrievable Catalyst for Hiyama Reaction: Functionalization of Magnetic Mesoporous Silica via Click Reaction

Catalysis Letters - A nitrogen ligand, i.e. 1,3-di-(o-aminophenoxy)-2-propyl propargyl ether (DPPE), has been synthesized and characterized. Magnetic mesoporous silica composite (MNP@SiO2-SBA) was...