Search results

Despite public unease, certain irradiated foods will be legally on sale in the UK in 1990. The irradiation process is outlined and its applications described. At present 36 countries have legalised the process and more than 40 different foods are treated. Although the process has as yet no detection method, all products so treated will be identified. The main initial application in the UK will probably be spices and herbs, whose decontamination is currently problematic.

The advantages and disadvantages of food irradiation are discussed, and examples are given. Particular emphasis is given to its effect on the nutritive qualities of food, especially in conjunction with other widely used techniques (pesticides, for example).

This paper aims to investigate the thermal performance involving larger heating rate, targeted heating, heating with least non-uniformity of the spatial distribution of temperature and larger penetration of heating within samples vs shapes of samples (circle, square and triangular).

Galerkin finite element method (GFEM) with adaptive meshing in a composite domain (free space and sample) is used in an in-house computer code. The finite element meshing is done in a composite domain involving triangle embedded within a semicircular hypothetical domain. The comparison of heating pattern is done for various shapes of samples involving identical cross-sectional area. Test cases reveal that triangular samples can induce larger penetration of heat and multiple heating fronts. A representative material (beef) with high dielectric loss corresponding to larger microwave power or heat absorption in contrast to low lossy samples is considered for the current study. The average power absorption within lossy samples has been computed using the spatial distribution and finite element basis sets. Four regimes have been selected based on various local maxima of the average power for detailed investigation. These regimes are selected based on thin, thick and intermediate limits of the sample size corresponding to the constant area of cross section, Ac involving circle or square or triangle.

The thin sample limit (Regime 1) corresponds to samples with spatially invariant power absorption, whereas power absorption attenuates from exposed to unexposed faces for thick samples (Regime 4). In Regimes 2 and 3, the average power absorption non-monotonically varies with sample size or area of cross section (A_c) and a few maxima of average power occur for fixed values of A_c involving various shapes. The spatial characteristics of power and temperature have been critically analyzed for all cross sections at each regime for lossy samples. Triangular samples are found to exhibit occurrence of multiple heating fronts for large samples (Regimes 3 and 4).

Length scales of samples of various shapes (circle, square and triangle) can be represented via Regimes 1-4. Regime 1 exhibits the identical heating rate for lateral and radial irradiations for any shapes of lossy samples. Regime 2 depicts that a larger heating rate with larger temperature non-uniformity can occur for square and triangular-Type 1 lossy sample during lateral irradiation. Regime 3 depicts that the penetration of heat at the core is larger for triangular samples compared to circle or square samples for lateral or radial irradiation. Regime 4 depicts that the penetration of heat is still larger for triangular samples compared to circular or square samples. Regimes 3 and 4 depict the occurrence of multiple heating fronts in triangular samples. In general, current analysis recommends the triangular samples which is also associated with larger values of temperature variation within samples.

GFEM with generalized mesh generation for all geometries has been implemented. The dielectric samples of any shape are surrounded by the circular shaped air medium. The unified mesh generation within the sample connected with circular air medium has been demonstrated. The algorithm also demonstrates the implementation of various complex boundary conditions in residuals. The numerical results compare the heating patterns for all geometries involving identical areas. The thermal characteristics are shown with a few generalized trends on enhanced heating or targeted heating. The circle or square or triangle (Type 1 or Type 2) can be selected based on specific heating objectives for length scales within various regimes.

The objective is to provide a quantitative insight on the dynamic nature of insolation on the building perimeter according to location, season and orientation. Such understanding is necessary for deciding on solar control strategies in diverse climatic environments, from low to high availability of insolation.

This study explores the seasonal changes of solar irradiation on building façades of various orientations at five locations with diverse climates (Reykjavík, London, Athens, Riyadh, Lagos). Solar data collected from the European PVGIS database is used to study the monthly distribution of global solar radiation incident on building façades at cardinal and ordinal orientations, as well as the proportions of its components.

The results illuminate the effects of the various factors on insolation. Among others: In all locations, horizontal surfaces receive more annual irradiation than any façade. In summer, east/west facades receive more radiation than south, hence solar protection on those directions is more important than on south. The beam fraction varies seasonally on south and north facades, but not so on east/west. Local atmospheric conditions can offset the importance of latitude on insolation levels and composition.

The paper utilises commonly available data to correlate insolation values and types under different factors across the globe, offering a better understanding on insolation for the design of greener buildings.

This study aims to determine the appropriate irradiation dose for induction of somaclonal variation in mass of unorganized parenchyma cells derived from sainfoin (Onobrychis viciifolia) tissues.

To investigate the feasibility of UV-B irradiation (312 nm), seeds and callus of sainfoin were exposed to five different intensities (20-100 per cent) for evaluating the effectiveness of phytochemical constituents and cellular behaviour.

Although percentage of seed viability reduced in 20 per cent intensity of UV-B irradiation compared with control seeds, the germination speed significantly enhanced from 3.58 to 5.42. The spectrophotometer analysis confirmed that concentrations of chlorophyll (a and b) decreased after UV-B exposure as compared with control callus. Also, carotenoid content showed significant differences among treated calli. Flavonoid and phenolic contents were observed to gradually increase when the non-irradiated callus subjected to 40 and 60 per cent intensities of UV-B irradiation, respectively. Observation on cellular behaviour such as determination of nuclear and cell areas, mitotic index and chromosomal aberrations were also detected to change in different intensities of UV-B irradiation. Fragmented and aneuploidy aberrations were only observed in exposed cells with more than 40 per cent intensity of UV-B irradiation.

In reality, radiocytological evaluation was proven to be essential in deducing the effectiveness of UV-B irradiation to induce somaclonal variation in callus tissue of sainfoin.

With the recent publication in the UK of draft legislation referring to the introduction of food irradiation in 1991, the food industry, consumers and regulatory authorities have at last had the opportunity to assess the likely impact of this controversial new process. Food categories to be licensed for irradiation are based on those under discussion within the EEC, with some modifications of more direct relevance to the UK. In this article the technological justifications for food irradiation are examined, together with the possible applications within the permitted food categories.

Irradiation is an effective means of increasing a food′s microbiological safety. However, it has not been widely adopted in the UK as a routine process. The major stumbling block is consumer resistance. Tests the hypothesis that this may be due to radiophobia (fear of irradiation). Perceptions of irradiation, gauged by means of questionnaire, showed a low awareness of irradiation and the treatment involved. In those aware of irradiation, radiophobia was apparent, demonstrated by both fear of radioactivity and worries of potential detrimental health effects after consuming irradiated foods. However, younger consumers appeared to be less radiophobic than older consumers. Consumers are generally unaware of process benefits. This demonstrates a need for education, if food irradiation is to be accepted on a routine basis.

The subject of food irradiation has provoked more reaction, more debate, more polarised positions among consumer organisations than any other recent issue in food policy. The contemporary consumer attitudes towards food irradiation are described, with the arguments for and against its use. It is argued that in the absence of any positive message from a respected source for its use the opposition – political, environmental, ethical, medical – has caused consumer attitudes to harden.

The purposes of this paper are to extend the shelf life of juice/fluids and reduce the thermal damage of their functional components. Thermal processing is a universal method used to extend the shelf lives of juice/fluids. However, combination processing thought to be beneficial in extending the shelf life with least possible thermal damage. The shelf life of the two thermally processed appetizer beverages, i.e. ginger beverage and karpurvalli beverage was established up to six months.

Both appetizer beverages were processed using irradiation in combination with heat treatment. A short thermal treatment at 95°C for 5 minutes was given to the bottled beverages, and these were then irradiated with different dosages of 1, 2 and 3 kGy. The samples were stored at room temperature (18-33°C), as well as at 37°C and periodically analysed for changes in pH, acidity, TSS, browning index, antioxidant activity and gingerol/carvacrol contents and for their microbiological quality.

The results revealed that in both products, the antioxidant activity and the gingerol/carvacrol content reduced, making these microbiologically safe up to eight months. However, combination of irradiation was not found suitable for the appetizer beverages due to more than 50 per cent losses in the functional components.

The combination of thermal and irradiation processing was effective to ensure microbial safety and extend the shelf life of beverages. However, it may not be suitable for preserving all functional properties.

The outcome is result of original work done, and information provided can be a preamble to the researchers targeting improved stability of functional beverages.

This paper aims to investigate the effect of different doses of gamma radiation on the micromechanical response (hardness properties and creep behaviour) of 96.5Sn-3.0Ag-0.5Cu (SAC305) solder alloys.

SAC305 solder pastes deposited on printed circuit boards (PCBs) were subjected to a reflow soldering process to form soldered samples. The soldered samples were irradiated with a gamma source at different doses (5–50 Gy). Nanoindentation testing was used to determine the hardness properties and creep behaviour after gamma irradiation.

The results showed that the hardness of SAC305 solder alloys gradually increased up to 15 Gy and then gradually decreased to 50 Gy of gamma irradiation. The highest hardness value (0.37 GPa) was observed on SAC305 solder alloys exposed to 15 Gy irradiation. Hardening of SAC305 solder alloy was suggested to be due to the high defect density induced by the gamma irradiation. Meanwhile, exposure to 50 Gy irradiation resulted in the lowest hardness value, 0.13 GPa. The softening behaviour of SAC305 solder alloy was probably due to the evolution of defect size in the solder joint. In addition, the creep behaviour of the SAC305 solder alloys changed significantly with different gamma irradiation doses. The creep rates were higher at a dose of 10 Gy up to a dose of 50 Gy. Gamma irradiation caused the SAC305 solder alloy to become more ductile compared to the non-irradiated alloy. The stress exponent also showed different deformation mechanisms with varying gamma doses.

Research into the micromechanical properties of solder alloys subjected to gamma irradiation has rarely been reported, especially for Sn-Ag-Cu lead-free solder. Thus, this research provides a fundamental understanding of the micromechanical response (hardness and creep behaviour) of solder, especially lead-free solder alloy, to gamma irradiation.