Effect of hydrothermal processing on carrot carotenoids changes and interactions with dietary fiber

The aim of the studies was to determine the effect of different methods of heat treatment on carotenoids changes and their interactions with insoluble and soluble dietary fiber. Three industrial varieties of carrot--Simba, Caropak and Fayette constituted the experimental material. Carrot cubes were subjected to heat treatment by putting in water with or without citric acid, or in a convection-type steam furnace. The total content of alpha- and beta-carotene was determined in all kinds of pureed carrots. Its amount bounded with insoluble dietary fiber and pectins was also determined. Changes in soluble and insoluble fractions of dietary fiber during hydrothermal treatment were also determined. It was found that the content of trans alpha- and beta-carotene in carrots decreased significantly (p < 0.05) after heat treatment, compared with the control sample. The loss observed during heat treatment in water was higher (up to 50%) than in the case of a convection-type steam furnace. The highest decrease in the content of insoluble fraction of dietary fiber and the highest increase in soluble fraction were observed after treatment with the use of steam. An analysis of interactions between carotenoids and dietary fiber fractions after hydrothermal processing shows their stronger affinity to forming bonds with pectins than with insoluble fiber. It was also found that the effect of heat treatment parameters was significant--the highest (by six times) increase in the content of beta-carotene bounded with pectins was noted in pureed carrots processed in a convection-type steam furnace.     

Quantification of uncertainty using Bayesian and bootstrap models to simulate the impact of nitrogen fertilisation on β‐glucan levels in barley

BACKGROUND: β‐Glucans have enjoyed renewed interest as a functional food ingredient, with current attention focused on optimising β‐glucan levels in finished products without compromising final product quality. In order to measure the uncertainty about the level of β‐glucans in barley, two different statistical methods (Bayesian inference and Bootstrap technique) were applied to measured levels of β‐glucan in three different varieties of barley grain (n = 83). RESULTS: The resulting probability density distributions were similar for the full data set and also when applied to smaller sample sizes, highlighting the potential for either method in quantifying the total uncertainty in β‐glucan levels. Bayesian inference was used to model the effect of nitrogen treatment on β‐glucan and protein contents in barley. The model found that a low level of fertilisation (50 kg N ha^?1) did not have a significant effect on β‐glucan or protein content. However, fertilisation above this level did result in an increase in β‐glucan and protein levels, the effect seeming to plateau at 100 kg N ha^?1. In addition, the uncertainty distributions were significantly different for two consecutive years of data, highlighting the potential environmental influence on β‐glucan content. CONCLUSION: The model developed in this study could be a useful tool for processors to quantify the uncertainty about the initial level of β‐glucan in barley and to evaluate the influence of environmental factors, thus enabling them to formulate their ingredient base to optimise levels of β‐glucan without compromising final product quality. Copyright © 2009 Society of Chemical Industry     

Influence of carbon support properties on the electrocatalytic activity of PtRuCu nanoparticles for methanol and ethanol oxidation

This work set out to explore the influence of kind and surface condition of carbon supports on the electrocatalytic activity of trimetallic PtRuCu alloy nanoparticles. The structure, composition, particle size and catalyst loading were determined by XRD, EDX, XPS, TEM and ICP-AES analysis. XRD studies revealed that support physical characteristics and surface conditions have an important influence in lattice strain, while XPS pointed out that a strong electronic interaction exists between the particles and the carbon support. Electrochemical experiments showed that the activated carbon black supported PtRuCu catalyst exhibits the best performance for methanol and ethanol oxidation and the lowest poisoning rate. The superior catalytic activity of this electrode can be rationalized in terms of metal-support interaction, Pt utilization efficiency and electrical conductivity of the carbon support. Furthermore, the as-prepared electrode exhibits 13 and 7 times higher activity towards methanol and ethanol oxidation when compared with a PtRu/C commercial catalyst.     

Ultrafine-Grained Plates of Al-Mg-Si Alloy Obtained by Incremental Equal Channel Angular Pressing: Microstructure and Mechanical Properties

In this study, an Al-Mg-Si alloy was processed using via incremental equal channel angular pressing (I-ECAP) in order to obtain homogenous, ultrafine-grained plates with low anisotropy of the mechanical properties. This was the first attempt to process an Al-Mg-Si alloy using this technique. Samples in the form of 3 mm-thick square plates were subjected to I-ECAP with the 90 deg rotation around the axis normal to the surface of the plate between passes. Samples were investigated first in their initial state, then after a single pass of I-ECAP, and finally after four such passes. Analyses of the microstructure and mechanical properties demonstrated that the I-ECAP method can be successfully applied in Al-Mg-Si alloys. The average grain size decreased from 15 to 19 µm in the initial state to below 1 µm after four I-ECAP passes. The fraction of high-angle grain boundaries in the sample subjected to four I-ECAP passes lay within 53 to 57 pct depending on the examined plane. The mechanism of grain refinement in Al-Mg-Si alloy was found to be distinctly different from that in pure aluminum with the grain rotation being more prominent than the grain subdivision, which was attributed to lower stacking fault energy and the reduced mobility of dislocations in the alloy. The ultimate tensile strength increased more than twice, whereas the yield strength was more than threefold. Additionally, the plates processed by I-ECAP exhibited low anisotropy of mechanical properties (in plane and across the thickness) in comparison to other SPD processing methods, which makes them attractive for further processing and applications.

     

Cherry (Prunus cerasus cv Montmorency) extract with standardised antioxidant potential as preservative for refrigerated storage of ground pork

Antioxidants occurring naturally are much sought‐after for their safety of use for human nutrition and strong preservative properties. The study was performed to determine the antioxidant potential of sour cherry extract and its effect (equivalent of 20 mg and 40 mg GAE kg^?1) on the quality of ground pork patties during 8‐day storage. The patties were analysed for antioxidant capacity, oxidation, profile of fatty acids, flavour, colour, sensory properties and aerobic bacteria count. Patties with addition of cherry extract (40 mg GAE kg^?1) showed higher antioxidant capacity of 844 ± 149 μmol TE L^‐1 on the last day of the storage than the control group where the result was 480 ± 81 μmol TE L^‐1. The addition of extract caused lower overall increase in lipid oxidation and prevented loss of redness even on the last day of the storage. Flavour changes resulted from oxidation and decrease in the amount of desirable volatile compounds in storage. The application of the extract from Prunus cerasus combined with vacuum packaging inhibited both oxidation and quality deterioration of pork patties in cold storage.     

Microstructure and magnetic properties of Cu90−xCo10Nix–7.5% SmCo5 composite alloys prepared by mechanical alloying and hot pressing

Nanocrystalline composites of Cu_90?xCo₁₀Ni_x (x?=?0, 10, 20?wt-%) alloys reinforced with 7.5?wt-% of intermetallic SmCo₅ particles were prepared by several processing steps. The production of these alloys started with the synthesis of Cu_90?xCo₁₀Ni_x powder alloys by mechanical alloying of pure Cu, Co and Ni in a planetary mill for 30?h at 250?rev?min^?1. As a second step, intermetallic SmCo₅ particles were added, and additional milling was performed for 10?h. The resulting powders of both milling processes were characterised by means of an X-ray diffraction method, a scanning electron microscopy and an electron probe microanalysis. As a final fabrication step, Cu_90?xCo₁₀Ni_x–7.5% SmCo₅ alloy powders were consolidated by hot pressing under 88?MPa for 75?min at 750°C in an argon atmosphere. The resulting compacts are reinforced by the precipitation of Co(Ni) during consolidation, and the presence of second-phase particles of oxides and intermetallic SmCo₅.     

Characterization of piezoelectric films of foamed polyethylene obtained by extrusion

Foamed polyethylene (MDPE) films obtained by extrusion have been characterized by X-ray diffraction, thermogravimetric analysis and tensile tests. The piezoelectric properties have been determined by calculation of piezoelectric constant d₃₃, thermally stimulated depolarized current method and calculation of activation energy depolarization of electrets. It has been found that the crystallinity and internal morphology, including cellular structure, affect the possibility of an effective polarization in order to obtain a piezoelectric material from foamed MDPE. The conditions of processing have a great influence on the piezoelectric properties. The value of piezoelectric constant attains ~18 pC/N and ~75 pC/N for low stress range and diminishes for higher stresses, temperature T_m?~?72 °C and ~82 °C, approximate activation energy attains 2.67 and 3.28 eV, for compacted and non-compacted film, respectively. Because of the simple and cheap method of foaming PE films of piezoelectric properties it is worthy to take care regarding their application for pressure sensors.     

Structural characteristics and rheological properties of locust bean galactomannans: a comparison of samples from different carob tree populations

Water‐soluble galactomannans were isolated from the seeds of 12 carob tree populations grown in different regions of southern Greece. Their structures, molecular weight distributions and rheological properties were examined. The intrinsic viscosity values and estimated average molecular weights varied in the ranges 8.15–13.02 dl g⁻¹ and (2.3–3.9) × 10⁶ respectively. Molecular sieve chromatography showed large variations in the molecular size distributions. The Manp/Galp ratio varied between 3.08 and 3.82, as determined by GC analysis of the alditol acetate derivatives of the monomeric constituents. There were also differences in the relative distribution of the free (Manp‐Manp), monosubstituted (Manp‐Manp(Galp)) and disubstituted (Manp(Galp)‐Manp(Galp)) dyads of β‐(1→4)‐mannose, as revealed by ¹³C NMR spectroscopy of the native polysaccharides. The pseudoplastic behaviour of galactomannan solutions (10–20 g l⁻¹) was confirmed by steady shear and dynamic rheological tests. Aqueous galactomannan (5 g l⁻¹)–xanthan gum (5 g l⁻¹) mixed systems gave gels on cooling (G′ ≫ G″). Galactomannans with high limiting viscosities, high Manp/Galp ratios and a low proportion of the Manp(Galp)‐Manp(Galp) dyad yielded the strongest mixed gel network structures with xanthan, implying that interchain associations between the two polymers occur via the unsubstituted segments (‘smooth regions’) of the carob galactomannan chains. © 2000 Society of Chemical Industry