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This research presents valuable experimental data for predicting the use of microwave technology in a cake baking process, based on in-process baking characteristics, final product textural properties, and dielectric and moisture sorption behaviour, of both cake constituents and microwave-baked product, with direct comparison to conventional methods. Microwave baking all0'Yed for up to a 93 % reduction in baking time, in comparison with convective baking. Experimental moisture data were adequately quantified in terms of drying constant and moisture diffusivity, both of which increased with power output. Experimental temperature data were used to determine the sensible and latent heat produced during microwave and convective baking. Cake baked in the microwave oven at 250 W showed improved textural properties as compared to cake baked in the convective oven. During storage the hardness of convective-baked cake increased more significantly than that of microwave-baked cake, whereas cake microwave-baked at 900 W showed the greatest reduction in springiness and cohesiveness. In general, the dielectric properties of samples increased with increasing frequency. Samples of higher moisture content exhibited increased dielectric measurements, with the exception of the loss factor of sugar samples which decreased. The dielectric constant of batter and flour was relatively independent of sample temperature, whereas that of the sugar samples increased with increasing temperature. The loss factor of batter and flour samples decreased by a limited amount as temperatu~e increased, whereas that of the sugar samples showed a significant decrease in loss factor. During microwave baking, the dielectric properties of cake batter initially increased sharply and then decreased steadily until the end of the baking process. A Type II isotherm was observed for flour samples, whereas the sugar and microwave-baked Madeira cake samples where ofType III.

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Drying is one of the main unit operations employed within the food industry as a method of preservation and extended shelf life. Rehydration is a process aimed at the restoration of the raw material properties, where the degree of rehydration may be considered as a measure of the physical degradation of the material caused by drying. A need has been recognised by the food industry for a thorough knowledge of the rehydration process in order to produce better quality products that are acceptable from a safety perspective, whilst conserving energy. The influence of processing variables on the rehydration characteristics were quantified using moisture diffusivity coefficients, evaluated by Fick's second law of diffusion. Processing parameters which improved rehydration characteristics included temperature, microwave drying, blanching and pretreatment with ionic surfactants. Microwave power and mixing had a limited effect on rehydration kinetics. Solute addition reduced the effective diffusion coefficient, with the extent of the decrease being dependent on concentration. Empirical models were utilised in order to predict the process. of water sorption as a function of temperature and time. Product quality was assessed by examining the texture degradation and volumetric changes which occurred during the rehydration process. Parameters, which influenced moisture content and morphological properties of the dried material, were recognised as key determinants that have an affect on the quality ofthe product during reconstitution. The thermal resistance of bacterial spores associated with this class of food were evaluated at various levels of moisture content. Thermal resistance decreased with increasing moisture content and, therefore, if complete rehydration is not achieved, the severity of the intended thermal process may be reduced. Supplied by The British Library - 'The world's knowledge'

Cold pressed rapeseed oil is produced when the seeds from the Brassica napus crop are crushed at a low temperature. This research sought to investigate the extent seed pre-processing and cultivar could be used to alter the composition of cold pressed rapeseed oil in relation to bioactive compounds. It also aimed to characterise UK and Irish cold pressed rapeseed oils and compare them with other popular types of edible oils. Finally, a range of spectroscopic techniques and chemometric models were tested for their ability to detect the substitutional adulteration of cold pressed rapeseed oil with lesser value oils. With regards to cold pressed rapeseed oil pre-processing, microwaving and thermal roasting significantly increased the abundance of phenolic acids and the antioxidant activity of cold pressed rapeseed oil. The volatile composition was also significantly altered by these pre-processing techniques. Cultivar had little impact on chemical composition. Characterisation of a range of UK, Irish and French cold pressed rapeseed oils found that all oils adhered to quality parameters. French oils had significantly higher levels of antioxidant activity than UK or Irish. Cold pressed rapeseed oil had higher levels of phenolic acids than refined rapeseed oil and was also more stable under heat stress. Spectroscopic techniques (FT-IR, Raman, 400MHz NMR, 60 MHz NMR) were tested with chemometric models to see to what extent cold pressed rapeseed oil adulteration could be classified and quantified. Refined rapeseed oil adulteration in cold pressed rapeseed oil was best classified by the 400 MHz NMR, then Raman, FT-IR and 60 MHz NMR. Refined sunflower oil was best classified by the 400 MHz NMR, followed by FT-IR, then Raman and 60 MHz NMR. Levels of adulteration detection showed refined sunflower could be detected at lower levels than refined rapeseed oil.

There has been renewed interest in recent years to address the coating of sugarcane mill rollers, due to the advancement in the development of welding electrodes and wires for surfacing and the need to improve the productivity and extraction of 'Ul!!urcane juice. The aim ofthis study is to evaluate and compare the performance of .hlclded metal arc welding (SMAW) overlays with an experimental arc sprayed. ''(luting in order to identify an alternative process that performs equally or better than SMAW in terms of abrasive wear performance under specific environment. The ~,udy focussed on three main areas: solidification and microstructure, abrasive wear, hud corrosion. The SMAW and arc sprayed coatings were deposited using Fe-Cr-C electrodes amt ,m experimental Fe-Cr-B wire, respectively. Friction and abrasive wear tests Wlrt conducted using a modified block-on-ring tester that simulated the wear eoodltlons experienced in a sugarcane mill, while corrosion tests were performed lIltnJ Jmmcrsion and electrochemical methods. Microstructures of the as-deposited coatings were characterised using optical mt''''L'OPY, scanning electron microscopy (SEM), energy dispersive x-ray (EDX) IIld N=ret)' diffraction (XRD). The wear mechanisms were also investigated by lllminln~ the worn surfaces and subsurfaces using SEM. ('tmlpluison of the resulting SMAW coatings revealed that variations in the • .....hhm of the welding electrodes as well as welding procedure produced significant differences in the microstructure in terms of morphology of the carbides, distribution and proportion of the carbide phases, and microhardness. The arc- 'prayed coating exhibited better abrasive wear and corrosion resistance compared to the SMAW coatings. The amount and distribution of free chromium in the specimens were the primary factors that controlled the corrosion behaviour. The dominant wear m~~hnnisms controlling abrasion were found to be microploughing and microcutting In the hypoeutectic coating, and microcracking in the hypereutectic and are sprayed coatings.

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No description available.