The Schroeder paradox or how the state of water affects the moisture transfer through edible films

The objective of this work was to better understand the water permeation through edible films when water is either in its vapour or in its liquid state related to their physico-chemical properties. Film based on iota-carrageenans or sodium alginate, containing or not fat, and encapsulating or not an aroma compound (n-hexanal) have been prepared. Films were conditioned at three different relative humidities, 0%, 43% and 84%. The incorporation of the n-hexanal in both types of biopolymer modifies the mechanical properties of film matrix and has a synergistic effect when associated to fat. Increasing the moisture content induces film plasticization by decreasing the glass transition of the glycerol enriched phase. Only carrageenan displays similar value for the liquid water transfer rate whereas a discrepancy of the behaviour in contact of liquid or vapour was observed for the alginate-based film, confirming the Schroeder paradox due to swelling.     

Properties of spray-dried food flavours microencapsulated with two-layered membranes: Roles of interfacial interactions and water

Engineering the interface of oil-in-water emulsion droplets with biopolymers that modify its permeability could provide a novel technique to improve flavour retention in dry powders. The objective of this study was to determine if volatile compounds were more retained in dry emulsions stabilized by pea protein isolate (PPI)/pectin complex than that stabilized by PPI alone. The retention of ethyl esters during spray-drying increased with decreasing volatility of the encapsulated compound and ranged from 28% to 40%. The addition of pectin to feed emulsions was quite effective in markedly improving the retention of the three studied flavour compounds. In our previous work (Gharsallaoui et al., 2010), we showed that pectin was able to improve physical integrity of emulsion oil droplets during spray-drying. However, the pectin positive effect on both the droplet stability and the flavour retention at the time of spray-drying can also be explained by a protein molecular structure protective effect. Indeed, the obtained FTIR results showed that pectin was able to preserve the β-sheet secondary structure of pea protein when pea globulins/pectin complexes are heated. The study of the release characteristics of a flavour compound from dried powders showed that pectin addition did not affect the release profile mainly accomplished by the diffusion mechanism.     

Bleaching of defatted flaxseed meal to improve its usage as ingredient in food applications

Brown defatted flaxseed meal (FM) was decolourised by dilute hydrogen peroxide (HP). The bleachability was evaluated as function of the FM concentration (2.5%, 5% and 10%), HP concentrations (1%, 2% and 3%), pH (3, 6, 7 and 9), temperature (25, 50 and 75 °C) and reaction time (2, 5 and 10 min). The product whiteness and yellowness were better at pH 9% and 3% HP concentration. The bleachability was enhanced by increasing the temperature but was inversely proportional to the meal concentration. The colour L* value was the highest at 2.5% FM, 3% HP, pH 9 and 10 min at 75 °C (L* = 74.82 ± 0.56) and was the lowest at 10% FM, 1% HP, pH 3 at 25 °C during 10 min (L* = 36.17 ± 0.45). These results may be exploited to improve the profitability of the flax sector using bleached meal as ingredient in food formulations.     

Biopolymer interactions affect the functional properties of edible films based on agar, cassava starch and arabinoxylan blends

Edible films based on the binary combination of agar (AG), cassava starch (CAS) and arabinoxylan (AX) were studied with regard to their microstructure, moisture barrier and mechanical properties. Though the films appear macroscopically homogeneous, electron microscopy observations reveal a phase separation and dispersion, respectively, in AG–CAS and AG–AX blend film structures, whereas the structure of CAS–AX blend films seems homogeneous. In case high moisture (84% and 99% RH), neither the combination of AG and CAS nor the addition of AX into CAS can improve film moisture barrier properties, except at a lower RH (57%). Conversely, water vapor permeability (WVP) of AG based film is significantly reduced when AX is used as an “additive”. On the other hand, blending AG with CAS increases the surface wettability of AG films but not that of CAS films. Adding AG into CAS induces an improvement in elongation and tensile strength of CAS based films. Mechanical properties of agar based films are degraded when CAS or AX was added. The results suggest that AG is able to provide a very good cohesive matrix, which contributes to enhance the mechanical properties of other polysaccharide based films.     

Precision measurements of 14C in AMS — some results and prospects

Some of the factors affecting the precision in AMS measurements will be discussed and the specific developments undertaken to reduce the errors at the ETH facility are described. Based on a large number of ¹⁴C measurements we show the present limitations of our system and consider what improvements might be possible. Further, a comparison is made between high precision measurements of ¹⁴C and current achievements relating to Be, Al and Cl.     

Discrimination of heavy and light elements in a specimen by use of scanning transmission electron microscopy

Heavier elements have a larger scattering cross-section for elastically scattered electrons than lighter ones. Furthermore, the maximum number of scattered electrons is at higher scattering angles for heavier atoms. These differences can be used, in principle, to distinguish heavy and light elements from each other in dark field Scanning Transmission Electron Microscopy (STEM). We have achieved such discrimination in practice by collecting the electrons in a STEM experiment at two different angles. The information about the elemental composition that these two images together contain is visualized by forming linear combinations of the images which are specific for light and heavy elementsrrespectively. The results are demonstrated for a specimen consisting of platinum grains on a holey carbon film and for granulocytes stained with osmium tetroxide.     

Target preparation for milligram sized 14C samples and data evaluation for AMS measurements

Our preparation technique produces in a glow-discharge an amorphous carbon deposit on a copper substrate. The process starts with 1.6 cm³ CO₂ STP (900 μg carbon) which is reduced over hot zinc to CO and subsequently cracked in the discharge. The yield of the process is typically 80%. With these targets in the Zürich ion source ion currents up to 20 μA are obtained. The background of samples prepared with this technique is presently around 30 ka (2.5% MODERN). The precision after half an hour measuring time for a modern sample is 0.7% and 2.7% for a three half-lives old sample, including the errors of the background and the NBS oxalic acid measurement. The method we use to correct for the background of the preparation and the accelerator as well as for the fractionation in the accelerator is presented.     

Radiocarbon measurements on coexisting benthic and planktic foraminifera shells: potential for reconstructing ocean ventilation times over the past 20 000 years

In this paper the potential of AMS ¹⁴C dating of shells handpicked from deep sea sediments is explored. We show that while the age difference between planktonic (surface dwelling) and benthic (bottom dwelling) shells must carry information regarding paleocirculation rates, this message is likely obscured by effects associated with the coupling between bioturbation and dissolution and between bioturbation and abundance change. It is also possible that the ¹⁴C/¹²C ratio in planktonic shells was initially not identical to that in surface water and that the ¹⁴C/¹²C ratio in benthic shells was initially not identical to that in bottom water. These and other biases will plague all attempts to extract the desired information regarding circulation rate changes over the last 20000 years. However in sorting them out, much will be learned about the origin and history of the calcite particles found in deep sea sediments.     

Factors affecting the performance of internal control task team in high-tech firms

The rise of global trade and economic development is not only apparently grown in terms of volume but with value as well. Such spurt has evoked the risk management that is associated with export business, and can allow high-tech items fall into the hands of foreign military programs or terrorist organizations. The internal control compliance for export has set the in-house procedures for firms to adopt, facilitate, and abide with defined national export control requirements. This is crucial for firms to prevent potential violations on export rules and regulations. Introducing internal control program for export compliance can mitigate terrorist activities. This present study has taken Taiwan on board to determine the acquaintance of export risk and the implementation of internal control program through a team effort. Hence, the purpose of this study is to investigate the factors affecting the performance of internal control task team within a firm. The findings show that team-based incentives have a positive impact on team cohesion while knowledge sharing and knowledge integration have a significant impact on team performance. Furthermore, it is found that higher social-related risks and technical-related risks may increase team management risk, and the reduction in team management risk is beneficial to improve team performance.     

The development of computer‐based tools to support ergonomics in design education and practice

Abstract

Ergonomics is not always used effectively by practising designers, and is still seen as limiting their creativity. Reasons for this include: ergonomics information is not presented in a readily assimilated form to designers during their design education and later design activities; design decisions relating to ergonomics issues are not addressed and discussed systematically by all members of the design team during concept design; the user centred approach that ergonomics encourages in design is not always included as part of the education of future designers.

With computers being used more widely in design and design education, they could be used to deliver ergonomics information and help structure discussion of ergonomics issues amongst the design team from the earliest stages of design. This paper describes findings relating to the use of ergonomics in automotive design, and proposes two tools which could enhance the use of ergonomics in design education and in current and future design practice.