Influence of packaging on the quality maintenance of industrial bread by comparative shelf life testing

The research focuses on the evaluation of the effects of films with different thickness on the quality of industrial durum wheat bread. A comparative shelf life test was performed taking into consideration textural parameters, instrumental crumb colour parameters, crumb moisture and alkaline water retention capacity, considered as indirect indicators of bread staling. Sliced, durum wheat bread was packed into a system made of a thermoformed bottom, with thickness ranging from 225 to 275. μm, and a lid (121-125. μm), with comparable barrier properties. Results demonstrated that it is possible to reduce packaging by about 20% without affecting shelf life standards. The packaging systems showed comparable barrier performances, maintaining the modified atmosphere during 103 days. Texture profile analysis gave comparable results for packages at reduced thickness compared with conventional ones. Also, colour, alkaline water retention capacity and crumb moisture correlated well with bread ageing and did not significantly vary among packaging types

“Thermal-sprayed dielectric coating EM properties evaluation via free-space measurements at microwave frequencies”

At present, there is a lack of knowledge about the electromagnetic (e.m.) properties of alumina coatings in a wide microwave frequency range. In this paper complex permittivity of thermal sprayed alumina coatings were evaluated via free-space measurements. XRD, microstructural and microhardness characterisations were per-formed too. The results showed that the real part of permittivity is consistent with that found for bulk alumina, being the difference due to the complexity of the coating, which is composed by multiple phases originated during the deposition process. The bond coat measurements showed that it is possible to recognise an anisotropic texture of the coating

Electromagnetic and mechanical properties of silica-aluminosilicates plasma sprayed composite coatings

The physico-chemical and thermo-mechanical properties of aluminosilicate ceramics (high-melting point, low thermal expansion coefficient, excellent thermal shock resistance, low-density and good corrosion resistance) make this class of materials a good option for high-temperature structural applications. Al2O3-SiO2 compounds show an excellent refractory behavior allowing a wide use as wear-resistant thermal barrier coatings, in metallurgical and glass plants and in high temperature heat exchangers. Moreover, the low values of thermal expansion coefficient and of complex permittivity allow to extend the use of this ceramic for microelectronic devices, radome for antennas and electromagnetic windows for microwaves and infrared. The present article presents the results of an extensive experimental activity carried out to produce thick aluminosilicate coatings by plasma-spray technique. The APS deposition parameters were optimized on the basis of a surface response approach, as specified by design of experiments (DoE) methodologies. Samples were tested for phase composition, total porosity, microstructure, microhardness, deposition efficiency, fracture toughness, and modulus of rupture. Finally, coatings were characterized for their particularly interesting electromagnetic properties: complex permittivity was measured at microwave frequency using a network analyzer with wave guide. © ASM International

Proprietà elettromagnetiche di rivestimenti spessi

Si riportano i risultati relativi alla caratterizzazione del comportamento elettromagnetico di rivestimenti spessi Al2O3-SiO2 depositati con tecniche di termospruzzatura al plasma. I campioni sono stati realizzati mediante l’impiego di polveri ottenute in laboratorio con tecnica di spray drying e sono stati sottoposti ad una completa caratterizzazione microstrutturale, morfologica, compositiva e meccanica. I risultati ottenuti in termini di permittività complessa, misurata in banda X tra 8 GHz e 12 GHz, sono di particolare interesse applicativo ed hanno consentito l’ottenimento di rivestimenti con spessore minimo pari a 3 mm e dotati di bassi valori di permittività

Electromagnetic and mechanical properties of silica-aluminosilicates plasma sprayed composite coatings

The physico-chemical and thermo-mechanical properties of aluminosilicate ceramics (high-melting point, low thermal expansion coefficient, excellent thermal shock resistance, low-density and good corrosion resistance) make this class of materials a good option for high-temperature structural applications. Al2O3-SiO2 compounds show an excellent refractory behavior allowing a wide use as wear-resistant thermal barrier coatings, in metallurgical and glass plants and in high temperature heat exchangers. Moreover, the low values of thermal expansion coefficient and of complex permittivity allow to extend the use of this ceramic for microelectronic devices, radome for antennas and electromagnetic windows for microwaves and infrared. The present article presents the results of an extensive experimental activity carried out to produce thick aluminosilicate coatings by plasma-spray technique. The APS deposition parameters were optimized on the basis of a surface response approach, as specified by design of experiments (DoE) methodologies. Samples were tested for phase composition, total porosity, microstructure, microhardness, deposition efficiency, fracture toughness, and modulus of rupture. Finally, coatings were characterized for their particularly interesting electromagnetic properties: complex permittivity was measured at microwave frequency using a network analyzer with wave guide

CFD simulation of an HVOF process for the optimization of WC-Co protective coatings

Microstructured and nanostructured WC-Co composite coatings can be deposited by HVOF starting from commercial composite powders. However, the reduction in powder size of the ceramic reinforcement is responsible for a significant increase of WC reactivity, enhancing the decarburation phenomena taking place within the spraying torch, and potentially affecting the mechanical and tribological properties of the deposited coatings. In order to limit the thermal degradation of the reinforcement, it is therefore necessary to strictly control the main combustion parameters of the torch, such as composition, velocity and temperature of the combustion gases. Using a CFD code, thermo-chemical and gas-dynamic properties of the gas flow within an HVOF JP-5000 (Hobart Tafa Inc.) torch were simulated. Results of the simulation were used to reconstruct the thermo-chemical history of the powders during their residence in the gas stream

Nanostructured wear resistant WC-Co coatings deposited by HVOF

Nanocrystalline WC-Co coatings were deposited by high velocity oxy-fuel (HVOF) using nanostructured composite powders with the aim of increasing coating performance, especially in terms of wear and corrosion resistance. HVOF processing parameters (fuel flow rate, length of the torch barrel and spraying distance) were optimized on the basis of a surface response approach, as specified by design of experiments (DOE) methodologies. Nanostructured coatings were characterized and compared with conventional WC-17%Co coatings in terms of average size of carbides after spray, index of carbide retention (from XRD results), microstructural features (porosity, interface quality), microhardness, fracture toughness, friction coefficient and wear resistance. Significant improvements of coating mechanical properties were evidenced

Nanostructured wear resistant WC-Co coatings deposited by HVOF

Nanocrystalline WC-Co coatings were deposited by high velocity oxy-fuel (HVOF) using nanostructured composite powders with the aim of increasing coating performance, especially in terms of wear and corrosion resistance. HVOF processing parameters (fuel flow rate, length of the torch barrel and spraying distance) were optimized on the basis of a surface response approach, as specified by design of experiments (DOE) methodologies. Nanostructured coatings were characterized and compared with conventional WC-17%Co coatings in terms of average size of carbides after spray, index of carbide retention (from XRD results), microstructural features (porosity, interface quality), microhardness, fracture toughness, friction coefficient and wear resistance. Significant improvements of coating mechanical properties were evidenced

Parametric study of an HVOF process for the deposition of nanostructured WC-Co coatings

Nanocrystalline WC-Co coatings were deposited by high velocity oxyfuel from commercial nanostructured composite powders. Processing parameters were optimized for maximal retention of the nanocrystalline size and for minimal decarburation of the ceramic reinforcement. Thermochemical and gas-dynamical properties of gas and particle flows within the combustion flame were identified in various operating conditions by computational fluid-dynamics (CFD) simulation. Significant improvements of the mechanical properties of the coatings were obtained: a decrease of the friction coefficient was measured for the nanostructured coatings, together with an increase of microhardness and fracture toughness