This research project was designed to investigate the chemical and physical changes in pork pies during storage. Lipid oxidation and moisture migration were found to be the parameters of most importance, with protein cross-linkaging and colour changes in the meat filling "'having' less of a deteriorative effect on pie shelf life. The extent of lipid oxidation and the development of rancidity (taste and odour) were found to be affected by cooking, the age of the meat and back fat in the meat filling and by their storage conditions (temperature and time). An increase in all or any of these parameters was found to increase the rate of rancidity development. On the other hand the rusk and the seasoning mix used in the meat filling of the pies, were found to reduce the rate of rancidity development. This antioxidant activity was investigated further. In the rusk, substances produced by the maillard browning reaction during the course of its manufacture were found to be antioxidative. However prolonged heating, although it produced a rusk with high antioxidant activity, had lowered its water binding capacity sufficiently to prevent its use in the meat products where water has to be bound to an inert filler. The antioxidant component of the seasoning mix was found to be white pepper, with the ethanol soluble fraction exhibiting this activity. Lipid analyses showed that rancidity developed parallel to the loss of the unsaturated fatty acids which had a chain length of 16 or above carbon atoms; and a concomitant rise in the concentration of short chain fatty acids and aldehydes, especially those having five and six carbon atoms in the chain length. The level of hexanoic acid (C6: 0) rose as rancidity developed, being development most marked in the pies with the fastest rate of rancidity development (i. e. those devoid of both the rusk and the seasoning mix). Moistture migration, both from. the atmosphere and from the jelly into the pastry (especially into the brown outer layer of pastry) resulted in an increase in moisture content, and a decrease in texture, of the pastry. Threshold levels for these two parameters were established above and below which respectively the pastry was deemed unacceptable, and these values were used subsequently in the investigation to assess the effect of various products on shelf life extension. Simultaneous lowering of the relative humidity (r. h. ) of the external atmosphere, and lowering of the jelly aw to levels at which to prevent moisture migration into the pastry resulted in a 35 day shelf life for the pies. However the use of glycerol to reduce the jelly aw to 0.56 resulted in an unpleasant taste to the pie. Lowering the jelly aw to 0.84 gave an extension (of at least 2 days) to the usual 8 days shelf life. Unfortunately attempts to achieve this aw (0.84) by the use of binders and pfi, were unsuccessful. Similarly the use of cetyl alcohol as a moisture barrier within the pork pie was not effective. The formation of a gelatin-lactein cogel, showed excellent potential for reducing moisture migration in pork pies.

The Rice Krispies™ process consists essentially of the cooking of short or medium rice grains, followed by a mechanical compression between two rolls (bumping), a tempering step and a toasting operation (puffing) which expands the grains into the finished product. The objectives of this project were to clarify which molecular phenomena take place inside the rice grains during the process and to facilitate the improvement and optimisation of the process parameters. The composition and gelatinisation behaviour of seven different raw rice varieties used either in the United States or the United Kingdom were studied. The glass transition of the cooked rice material was determined by dynamic mechanical thermal analysis (DMTA), which allowed each step of the process to be mapped onto a temperature / moisture content state diagram. The bumping step of the process and its effect on the various molecular entities present in the cooked rice were studied in details. Amylose was found to form complexes with the lipids present in the material during cooking, and these reinforced the cooked rice grain structure. One of the roles of the bumping could be to partially dislocate these amylose-lipid complexes to enable the rice grains expansion at the puffing step of the process. The bumping also reduced the molecular weight of amylopectin, which is thought to weaken the rice grains structure and improve the puffed grains expansion. The mill gap between the bumping rolls was the key factor determining the quality of the puffed product. The temperature at which the rice grains are bumped had a secondary influence on the quality of the puffed rice, within the range 26°C to 57°C. The RVA provided a very effective method to categorise post-bumped samples and could be a useful diagnostic tool in case of production problems. Evidence of physical ageing and moisture content equilibration during the tempering step was found. Physical ageing did not have a detectable effect on the expansion of the rice grains, while it was important that moisture content was equilibrated inside the grains to ensure a proper puffing. Finally, correlations were found between the puffed rice grains expansion and the post-bumped grains height recovery, which made it possible to predict the quality of the expanded grains from the characterisation of the post-bumped rice. Overall, the project is a good example of the application of general starch science concepts to the study of a specific industrial process.

No description available.

The reactivity and micro-structure of three coals and two cokes used in iron and steel manufacture have been studied by a variety of techniques, including gas sorption analysis, thermal analysis and microscopy. Changes in surface areas and porosities of the coals and cokes during combustion have been determined by a gravimetric nitrogen sorption technique at 77K. The cokes and coals have been studied by thermal analysis under isothermal and dynamic conditions in different gas atmospheres. Rates of reaction have been correlated with surface area changes. Attempts have been made to calculate activation energies from Kissinger plots of DTA data. Microstructural changes in the cokes and coals during carbon burn-off have been investigated by electron microscopy. Relative porosities have been estimated by image analysis. Mechanical strengths of the cokes have been measured and correlated with porosity data. Selected metals in the carbons have been determined by flame photometry, atomic absorption spectroscopy and Mossbauer spectroscopy. The composition of residual mineral matter (ash) has been investigated by X-ray diffraction. The chemical compositions of the coal distillates have been characterised by ir/uv spectrosopy, NMR spectroscopy and by GC-MS techniques. Calorific values of the carbons have been determined. Results are discussed in relation to previous work and to applications 1n blast furnace practice. In coal combustion the surface areas increase during the initial stages of carbon burn-off, reaching maximum at about 50% burn-off before decreasing. The increases are considerably higher at 400° and 500° C than at 300° C for all three coals. Hysteresis data from the sorption isotherms show that the coals develop full ranges of mesa-porosity and some micro-porosity during burn-off at the higher temperatures. However, the coal oxidation is only slightly accelerated, since most of the new surface is located in the micro- and meso- pores where access to atmospheric oxygen is restricted by slow diffusion, so that the earlier stages of oxidation are approximately linear with time. This improves our knowledge of current empirical industrial carbon solution tests. There is comparatively little change in surface during the coking of the Coals at 1000° C and only restricted sintering of the coal ashes at 300- 500° C. In the combustion of the cokes in carbon dioxide at 1000° C the maxima in surface areas occur within 25% burn-off. However, one of the cokes shows a second maximum at later stages of burn-off, ascribed to the European component in the parent coal blend. This gives a more uniform rate of burn-off which is advantageous industrially.

Cotton and wool have long dominated studies of the English textile industries, relegating silk manufacture to no more than a minor role in the British economy. Regional studies have likewise tended to concentrate upon areas dominated by a single feature or single industry. This thesis aims to address the economic and social impact of a silk industry established in the predominantly rural area of South West Hertfordshire. Here the indigenous population had other opportunities for employment, agricultural labour of various kinds forming the greatest occupational group. The straw plait absorbed female and child labour in the districts of Berkhamsted and St Albans, in direct competition to the silk mills, while the rag factories supplying the paper industry offered competition to the silk mills of Watford and Rickmansworth. Any industry dependent upon imports is especially vulnerable to external pressure, and an overview of the national situation regarding the silk industry in England, and of the particular problems besetting manufacturers during the late eighteenth and nineteenth centuries, is therefore essential to an understanding of the situation in the rural semi-industrial districts. The chapters of this thesis therefore follow the story of silk production from the wider context of the national industry to the specific mills of Hertfordshire, asking first, why the establishment of an English silk industry was so important. Themes explored in later chapters are already discernible in the early history of the silk industry: the high involvement of women; the apprenticeshipo f children; the interventionist role of government; and the problem of the poor. The extent to which these factors impinged upon the relationship between master, worker, and the local district, and ultimately upon the viability of the Hertfordshire mills, form the central core of this study.

Image recognition is the process of classifying a pattern in an image into one of a number of stored classes. It is used in such diverse applications as medical screening, quality control in manufacture and military target recognition. An image recognition system is called shift invariant if a shift of the pattern in the input image produces a proportional shift in the output, meaning that both the class and location of the object in the image are identified. The work presented in this thesis considers a cascade of linear shift invariant optical processors, or correlators, separated by fields of point non-lineari ties, called the cascaded correlator. This is introduced as a method of providing parallel, shiftinvariant, non-linear pattern recognition in a system that can learn in the manner of neural networks. It is shown that if a neural network is constrained to give overall shift invariance, the resulting structure is a cascade of correlators, meaning that the cascaded correlator is the only architecture which will provide fully shift invariant pattern recognition. The issues of training of such a non-linear system are discussed in neural network terms, and the non-linear decisions of the system are investigated. By considering digital simulations of a two-stage system, it is shown that the cascaded correlator is superior to linear filtering for both discrimination and tolerance to image distortion. This is shown for theoretical images and in real-world applications based on fault identification in can manufacture. The cascaded correlator has also been proven as an optical system by implementation in a joint transform correlator architecture. By comparing simulated and optical results, the resulting practical errors are analysed and compensated. It is shown that the optical implementation produces results similar to those of the simulated system, meaning that it is possible to provide a highly non-linear decision using robust parallel optical processing techniques.

Deposition of amorphous silica (SiO2) and calcium oxalate (CaOx) on the calandria tubes of juice evaporators cause serious processing problems in Australian cane sugar mills. The removal of these deposits by mechanical and chemical means is a timeconsuming and costly experience. The cost of downtime and chemical cleaning can be several million dollars per year for the Australian sugar industry. The interactions between CaOx and SiO2 have not been investigated previously because conventional studies only address fouling by individual components. The present work evaluates their interactions using two experimental approaches: batch tests for assessing kinetic and thermodynamic behaviour, and fouling-loop experiments for examining composite fouling behaviour under different operating conditions. The above two approaches were employed both in the absence and in the presence of sugar to elucidate the effect of sugar on composite fouling mechanisms and to determine the controlling species responsible for composite fouling. The composite fouling experiments were performed in a novel closed-loop circulation system simulating the effect of feed composition of successive stages of evaporation cycle in a single run. In addition, the fouling-loop system was operated in a constant composition mode to study the effects of thermal hydraulic conditions on composite fouling. The combined information obtained from both the batch and fouling-loop tests in this study offer a unique insight into the mechanisms of composite fouling of CaOx and SiO2. Some of the highlights of the obtained results are as follows: ??? Identification of a complex interactive process in calcium oxalate monohydrate ??? silica (COM-SiO2) systems by investigation of the kinetics and thermodynamics of COM-SiO2 coprecipitation in water and sugar solutions, and an understanding of the mechanisms of these interactions; ??? Development of a novel fouling-loop system, which is simple, efficient and cost effective for the study of the effect of juice composition on scale formation in various stages of juice evaporation; ??? Elucidation of composite fouling mechanisms, e.g., a feed composition dependent fouling mechanism is proposed; ??? Isolation and verification of the existence of certain species in composite deposits, which is known to be thermodynamically unstable. In other words, it is established that calcium oxalate trihydrate is stable under certain conditions; ??? Evaluation of the role of thermal hydraulic operating parameters in determining the characteristics of subcooled flow boiling heat transfer and in determining the strength of the composite deposit; ??? Development and validation of an empirical model to predict the subcooled flow boiling heat transfer coefficients in water and sugar solutions; ??? Development of an analytical model incorporating the effects of operating parameters for COM and SiO2 composite fouling in sugar solutions. This model predicted the experimental data better than available models. Results of this work are significant, not only because they have made a valuable contribution to advance the fundamental understanding of heat exchanger fouling, but also because they may play a key role in the development of scale control and removal strategies to minimize the composite fouling in Australian sugar mill evaporators. For example it was found that, in order to effectively minimize the rate of composite fouling and reduce the scale tenacity, it would be necessary to control thermal hydraulic operating conditions, especially the fluid velocity, and to adjust the initial CaOx/SiO2 supersaturation ratio to the optimum value. To achieve the optimal CaOx/SiO2 ratio, certain device can be developed to sequentially measure oxalic acid and SiO2 concentrations in juice so that the correct proportions of chemicals can be added. Model simulations of the composite fouling rate may also effectively and economically provide comparative and relevant information essential for process optimisation and evaporator design

Thesis (M.S.)--Ohio University, March, 1997. / Title from PDF t.p.

Thesis (M.F.A.)--Rochester Institute of Technology, 1981. / Typescript. Includes bibliographical references (leaf 28).

Thesis (Ph. D.)--Johns Hopkins University, 1930. / Date in imprint changed in manuscript to 1931. Biographical note. Bibliography: p. 82-87.