The PhD describes the social science and technical design of an innovative clean cooking stove that also generates electricity for use in developing countries. Key areas of learning adding to the research pool are: 1. Method for comparing costs of competing designs early in the research process before detailed design has been undertaken. 2. Use of state-of-the-art industrial design processes combined with social science investigations to direct research to meet end-user needs 3. Design of a low-cost, low thermal mass hot heat exchanger for use in thermo-acoustic engines 4. Design of a low-cost, low-mass Linear Alternator suitable for use in thermo-acoustic engines 5. Half-wave thermo-acoustic engine configuration with low-onset temperature suitable for operation with wood or dung as the fuel. 6. Use of an electrical analogue to predict unusual thermo-acoustic behaviour such as squegging and time-based pressure variations. The document is an extended abstract pulling together Riley’s 6 years of research and publications from the Score project, into one coherent theme as required by the University of Nottingham quality manual for staff engaged in research. The document describes the background of thermo-acoustics and how the project has enabled the science to progress from mainly rig-based engines to a manufacturable product. The research management process and techniques used to reduce project risk are highlighted, beginning with social science research into end-user requirements, system design, component design, testing and production cost predictions.

Tomatoes often lack the characteristic good taste that consumers expect. In recent years, the fruit and vegetable industry has focused on traits such as yield, colour, and fruit size; however, flavour has been largely forgotten, at least for varieties that are grown in bulk and are cheap to purchase. Tomato volatiles are one of the most important flavour contributors along with sugars and organic acids. Over 400 volatiles are present in tomato, but only about 30 are considered critical to tomato flavour. The purpose of this study was to identify volatile Quantitative Trait Loci (vQTL) using publicly available Solanum pennellii and Solanum habrochaites introgression lines (ILs). Detection of vQTL is an essential milestone for identification of candidate genes involved in tomato flavour. Identification of vQTL was undertaken by screening the ILs using Atmospheric Pressure Chemical Ionisation Mass Spectrometry (APCI-MS) and Gas Chromatography Mass Spectrometry (GC-MS). Additionally key volatiles and their interactions were evaluated in a series of sensory experiments using tomato juice and tomato purée. The study revealed that, the S. pennellii population had several major effects including those on IL1-4, which had a vQTL for C6 volatile E-2-hexenal. It was possible to identify a sub-IL, 1-4-1 that also harboured this vQTL. In this IL1-4-1 region of chromosome 1, 122 genes were present including a possible, candidate gene likely to be involved in lipoxygenase pathway. The sensory experiments showed strong impact of methyl salicylate on other volatiles; E-2-hexenal and citral showed positive effects in purée studies. Determined taste detection thresholds for volatiles in tomato juice and purée were established. Keywords: volatile, genes, tomato juice, tomato purée, flavour.

The work presented in this thesis describes the use of scientific research in the development of novel texture and flavour experiences and their potential for use in fine gastronomy. In order to create an interesting textural experience, modified celluloses were investigated. Their unique property is that they have the ability to gel at high temperatures, but return to the solution state upon cooling. This phenomena was used to test the hypothesis that hot gels made from these materials could melt at temperatures greater than mouth temperature, providing a melt-in-the-mouth sensation on consumption in a fashion analogous to gelatine. Melting temperatures of these hot gels were calculated using the techniques of rheology and differential scanning calorimetry, as well as more empirical methods, and results showed that gels made from a number of different hydroxypropylmethylcelluloses (HPMCs) displayed melting temperatures above 37°C. In order to predict their flavour release properties, the mixing efficiency of the solutions were investigated and results showed that solutions made from the lower molecular weight HPMCs showed more desirable mixing behaviour, suggesting better flavour release than those made from high molecular weight HPMCs. Furthermore, these solutions also had more desirable mouth-feel attributes, as determined by sensory analysis, yet their inherent flavour attributes were less pleasant. Therefore, modified celluloses show potential use in producing hot gels that melt in the mouth. The second part of this thesis was focussed on developing novel flavour experiences, and this was done by creating drinks that changed their flavour as they were consumed. The development of a tomato flavoured drink, whose flavour changed due to the sequential heightening of its tastant profile, is described here, and it was found that the presence of each tastant at a volume needed to invoke swallowing was more important than the order in which the tastes were administered in terms of ensuring that each different flavour was perceived. In addition, a banana flavoured drink whose flavour changed on consumption to mimic a ripening banana was also created, and this work showed the importance of the matrix on flavour perception at both the physical and psychological level, which has important consequences in general in the development of flavoured products. The work described in this thesis therefore shows the potential use that scientific research can play in aiding the creation of novel concepts applicable to the world of fine gastronomy.

In order to improve public health, active measures are taken to lower the salt (sodium chloride) consumption of the population. However, significant effort is required to reduce salt content in processed foods without adversely affecting taste, flavour and consumer preference. This research aimed at investigating how the saltiness efficiency of sodium chloride could be improved. The first approach investigated the relationship between rheology and taste perception to evaluate whether it is possible to enhance saltiness perception through careful design of product rheology. The objective was to identify the flow parameters correlating to saltiness perception. The shear rate relevant to saltiness perception was investigated using a range of typical solution flow behaviour (Newtonian, shear-thinning, yield behaviour). It was found that saltiness perception is related to viscosity measured at low shear (1-10 s-1) and not to zero shear or high shear viscosity. An enhancement of saltiness perception was found for very high polymer concentrations, which could be explained by the increased osmolality of these solutions. Subsequently, food grade Boger fluids (Newtonian fluids of high elasticity) were formulated and characterised to investigate whether extensional viscosity impacts saltiness perception. As no clear effect was reported, hypothesised to be due to the unfavourable mouthfeel of the relatively thick fluids, an alternative approach using low viscosity polysaccharide solutions of identical shear behaviour but of different extensional behaviour was taken. Extensional behaviour of polysaccharide solutions in large deformation flow has received very little attention compared to shear flow behaviour and was characterised here using the techniques of filament break-up and microfluidics as preliminary work for future sensory studies. Large differences in elasticity among polysaccharides and singularities of polysaccharides compared to synthetic polymers were found. As a second approach it was investigated whether duplex emulsions could be stabilised by chemical cross-linking of proteins adsorbed at the oil-water interface. The interest in duplex emulsions is based on the hypothesis that increase in the salt concentration in the continuous product phase of an emulsion-based food may increase saltiness perception. Formulation of stable food duplex emulsions is challenging and here it was shown that chemical cross-linking of Bovine Serum Albumin (BSA) adsorbed at the oil-water interface improved stability towards coalescence and emptying out of the internal water phase. The interface of single oil-in-water emulsions was also successfully cross-linked. Both the industrial impact and fundamental interest of this research were discussed.

Hospitality and tourism are important sectors of any economy. In the service sector, achieving a level of service quality that satisfies customers usually results in a competitive advantage in the market. The concept of service quality in hotels has been the subject of many research studies and there are numerous published works in the field. However, only a few studies have focused on the determinants of service quality for hotels using a set of comprehensive criteria. Thus, conceptualizing a service quality model that identifies the dimensions of service quality that affect customers' satisfaction is needed for hotels. In addition, the role of operations management practices in managing service quality cannot be denied. The available literature on the hotel industry in terms of managerial practices is unfortunately poor and needs to be enriched. Logically, better operations management practices in managing hotels' service quality would have a direct positive impact on performance, but there could also be some indirect (mediating) impact on performance through customer satisfaction. The purpose of this research is to build an effective model for measuring service quality in the hotel industry through critical evaluation of the available literature in service in general and hotels in particular. The built model has aspects of customer's perceptions of service quality, management's perceptions of operations management practices and of performance. The existing literature has been used to conceptualize a service quality model that meets the purpose of this research. The conceptualized model has eleven dimensions; seven for customer perceptions on service quality and four for management perceptions of operations management practices in managing service and on performance. The dimensions of customer's perceptions are: employee behaviour/attitude, price fairness, non-technological tangibility, technological tangibility, in-consumption positive emotions, in-consumption negative emotions and overall customer satisfaction. The introductions of technology and in-consumption emotions are one of the main contributions of this research. Though previous researchers have supported the use of these two criteria in evaluating service quality of hotels, the researcher is not aware of any quantitative service quality study that used these two dimensions. Of particular note is that emotion is evaluated in terms of its frequency of occurrence during the service experience, unlike previous studies. The dimensions of operations management practices are managing employees, managing process and customer feedback. Managers' perceptions on hotel performance were also included in the conceptualized model. Linking operations management practices to overall customer satisfaction is another contribution of this research. Many previous studies attempted to understand the direct link between service quality and performance; although there is an equally dominant view in the literature that the relationship between service quality and performance could be more complex. Hence, there could also be some indirect (mediating) impact on performance through customer satisfaction. This research tested whether there is a mediating effect by customer satisfaction between operations management practices and performance. This test also contributed to the existing literature on service as a whole and on hotels in particular. Moreover, a moderation test of customers' characteristics; gender, purpose of hotel stay, age and education, is also performed in this research, further strengthening the value of this research. Responses from two independently administered surveys have been used in this research, one for hotel customers and a second for hotel managers. Data has been collected in two international airports and a number of hotels in Oman. A sample size of 689 observations was used to test the relationships developed in the conceptualized model. First, factor analysis was carried out on the data to validate the developed dimensions. Exploratory factor analysis (EF A) was performed to explore the dimensions and then confirmatory factor analysis (CFA) was performed to confirm the validity of the dimensions. The measurement model has been checked for its reliability and validity using criteria developed from the available literature. Then, the developed hypotheses were tested using a structural equation model (SEM) using partial least square approach (PLS-SEM). The results have generally confirmed the original conceptualizations. All service quality dimensions, namely employee behaviour/attitude, non-technological tangibility, technological tangibility, positive in-consumption emotions and negative in-consumption emotions and operations management practices, namely managing employees, managing process and customer feedback, have been found to have a statistically significant influence on the overall satisfaction of guests. The hypotheses on the moderating effects of customers' characteristics were partially supported. The results proved that management practices have direct and significant effects on performance. In addition, customer satisfaction was found to be partially mediating the relationship between operations management practices and performance. Knowledge about the dimensions of service quality and operations management practices in hotel industry is valuable for managers in the context of managing and assessing the quality of their service. This research has used the available literature to build a model that has interrelationships between operations management practices, customer perceptions of service quality and performance in the hotel industry. The model has introduced two new dimensions, technology and emotions, which has enriched the literature of service quality evaluation. There is no doubt that managerial awareness of the dimensions influencing customer satisfaction will help in developing competitive advantages for their hotels. In addition, linking operational management practices to overall customer satisfaction and testing its direct and indirect effect on performance has also contributed to knowledge. Thus, in order for managers to increase the hotels' performance in terms of customer satisfaction, special considerations need to be carried through their practices. Moreover, managers' awareness of the moderating role of the customers' characteristics will help in better managing the quality of service provided. The findings of this study in particular will open new directions for future research in the hotel industry in particular and the service industries as a whole.

The impact of salt (sodium chloride) on the wheat dough was studied, with a particular focus on the state and distribution of water and sodium in the dough system. In this study, dough samples were prepared using the same processing techniques as in commercial bakery (i.e. Chorleywood Bread Process) and were investigated simultaneously using molecular spectroscopy 1[subscript]H and 23[subscript]Na NMR), deformation stress measurement (Kieffer test, Texture Profile Analysis and Chen-Hoseney test) and calorimetry (DSC). A progressive study of experimentation was carried out in which dough samples between zero and 5% added salt (on flour base) to exaggerate the effects of salt. Furthermore, test baking was also used to study the mechinability of doughs. All of the techniques studied enabled the construction of a complete picture of the sequential events occurring when salt is reduced. Test baking confirmed that machine moulding of bread dough became more difficult at lower salt contents. This was more apparent when dough temperature was elevated, or when the delay time between mixing and moulding was increased. Laboratory measurements were not able to distinguish the increase of stickiness occurring in the low salt (1.4%) doughs and modifying the method also failed to establish variations in stickiness, although changes in the hardness of the dough at the different salt levels were detectable. Measurements of the dough fluid phases were compared using three techniques: isolation of aqueous phase through ultracentrifugation, freezable water as measured by differential scanning calorimetry (DSC) and proton mobility using low field nuclear magnetic resonance (1[subscript]H NMR). Salt increased the amount of dough liquor expressed on ultracentrifugation, however, the amount of freezable water and the molecular mobility of water (T2) did not show significant changes. The findings suggest that the gluten-starch matrix is sensitive to salt in way that it affects the "drainage" properties and the capillarity of the dough matrix, but not the intrinsic levels of fluid in the dough. The distribution of salt on the dough was also investigated using 23[subscript]NaNMR. A large proportion of the salt added was not detectable with this technique and could be thought of as immobile. Increasing the concentration of sodium in the dough gave the same proportion of "bound" sodium. It would seem to be the starch component in the flour that dominated the sodium binding in the dough samples. Salt may exert its effects through polymer-polymer interactions rather than polymer–water interactions and its exact influence on cereal products performance still needs to be established before the reduction of salt is a viable option for commercial bakers.

Despite a considerable amount of research investigating factors that influence the development of food preferences, there is very little research considering factors associated with food items themselves and the cognitive processes used by children to determine acceptance or rejection of a novel food. When offered a new food, children will see what colour, size and shape it is and may be able to determine its texture. In addition, they will be able to smell the food and may even be informed of what the food is called by their parents labelling it. Hence children will have a significant amount of knowledge of what the food they are being offered is like. It may therefore be reasonable to suggest children will use this knowledge and make comparisons to prior experience with 'similar' foods. This thesis presents three experimental chapters which aim to explore the role of perceptual (e.g. colour, texture and size) and cognitive (categorisation) factors on the development of food preferences. Chapter 2 presents an Explicit Preference Task, which enables children to self-report on their food preferences, complemented by parental report Food Preference and Frequency questionnaires. Chapter 3 presents a Longitudinal Food Diary method exploring the relationship between preference and exposure. Finally in Chapter 4 using a series of match-to-sample experiments to consider if children use colour as a basis for categorisation of food objects, a comparison is made against non-food objects. Results indicated children to dislike food colours particularly associated with vegetables more so than other food colours. This was found to be related to the amount of exposure they had to those foods and specifically results indicated children to use food colour as a basis for rejection of novel foods. It was also observed that whilst children use shape as a basis for categorisation of non-food objects, they are more inclined to categorise foods on the basis of colour.

Tomato (Solanum Iycopersicum) puree is created by homogenising the flesh of tomato fruits. The viscosity of this material and the fibrous content is of commercial interest. Tomato puree consists of suspended particles (consisting of whole cells, broken cells and cellular fragments) in an aqueous serum. The contribution of the non-soluble and soluble material to tomato puree rheology was studied with reference to the varying composition of solids and firmness of tomato fruit at four stages of ripeness; mature green, breaker, pink and red ripe. When purees from the red ripe and the breaker fruit with initial total solids contents of approximately 5.5% were diluted to a range of total solids content (between 5 and 1%), both samples decreased in viscosity with total solids. To observe the effect of the serum on tomato puree viscosity, the pellet fraction containing the particles was spun out of the tomato purees by centrifugation so that the particle fraction and the serum could be assessed separately. On further investigation, the viscosity of puree was shown to be affected only to a small degree by the viscosity of the serum. The fact that stirred viscosity was independent of whether the suspension medium constituted of sucrose solution or serum phase showed that little contribution to the viscosity is coming from the soluble hydrocolloids in the tomato sera. Most dominant for viscosity was the particle fraction. The particle fraction was affected by the maturity of the fruit which in turn was associated with changes in fruit texture, particle size and size distribution of the puree. The particles did not behave as rigid spheres, as shown by the large departure from the corresponding Krieger Dougherty fit (Krieger and Dougherty 1959), ripened fruit deviating the furthest. This suggested the more ripened fruit has softer (less rigid) particles, which was shown to have softer tissue before the pureeing process. This may also have made the tissue more susceptible to rupture into smaller particles during pureeing. Quantitative data for size distribution measured by laser light scattering show that as the tomato ripened from green to red, particles were smaller; the mean diameters for the particles in the four puree samples were 893J.lm (mature green), 542J.lm (breaker), 377J.lm (pink), and 262J.lm (red ripe) and of a broader size distribution. Pureed mature green (unripe) fruit were shown to offer more potential as an effective natural viscosifier for foods such as soups and sauces, but they may not meet requirements of taste or colour. The last part of this research (chapter 7) therefore focused on tomatoes with variations in their genes rather than ripeness, harvested at breaker + 7 days. Tomatoes at the same stage of ripeness from the Solanum pennel/ii tomato introgression lines (ILs) were grown and harvested from the glass houses at the University of Nottingham. A screening process was developed to compare the viscosity of small samples of tomato puree from 55 of the ILs, 164 fruits in total; the remaining 21 lines did not produce quantities of fruit sufficient for analysis. The samples were diluted with water to the same total solids of 3.5%. The mean stirred viscosity value for all the lines measured was 132 ± 45 cPo The viscosity was calculated from typically three replicate measurements on three individual fruits per line. Although the particle volume and weight fraction of the puree and the initial total solids content had a strong influence on stirred viscosity, it was shown that the variation between individual fruit was greater than that between the different ILs. Previous texture studies of the IL lines showed marked variations yet there was no clear relationship between the puree viscosities and the expected texture of the whole fruits.

This research project fully defines and evaluates a new approach in sensory omission testing, based on the same-different test (ASTM E2139-05 2011) and the Thurstonian measure d′. The applications of this new approach were investigated to fully characterise sweet and savoury flavour models and to investigate interactions between flavour compounds. Panels of naïve assessors conducted a series of omission tests using both a strawberry (9 volatiles) and a savoury (10 volatiles) flavour model. Using the Thurstonian d′ as a measure of the sensitivity of the discrimination test, results showed that the new approach using the same-different test was more sensitive compared to the more traditional approach using the triangle test: the d′ values obtained using the same-different test were 1.2 to 3.5 times higher than the d′ values obtained using the triangle test. It was hypothesised that the evaluation of three samples in the triangle test generated additional noise related to carry-over, sensory fatigue and memory effects. In particular, the triangle test requires that the three successive stimulus sensations are stored into memory until the discrimination test has been completed. The same-different approach was then successfully applied to (i) determine the relative importance of individual volatiles in ortho- and retronasal flavours (ii) assess interactions between volatiles in mixtures, and (iii) investigate interactions between congruent tastes and aromas in flavours. Results showed that cis-3-hexen-1-ol, 4-hydroxy-2,5-dimethyl-3-furanone and ethyl butanoate play a key role in the strawberry flavour, while sulfur compounds play a major role in the savoury flavour. For both the sweet and the savoury flavours, orthonasal perception was more sensitive to the removal of individual volatiles and this was attributed to different efficiency in delivery to the olfactory receptors. The same-different approach highlighted synergistic, suppressive and blending interactions between volatiles within flavour mixtures. In particular, the presence of 4-hydroxy-2,5-dimethyl-3-furanone increased the assessor sensitivity to the removal of other individual volatiles in the savoury flavour. Cross-modal interactions were highlighted within the strawberry flavour, particularly where congruency between taste and aroma could be identified. The omission approach brings a novel contribution to sensory science as it allows further analyses and a deeper understanding of flavour. This study pioneers the use of the Thurstonian d′ for omission experiments, enabling the relative importance of the individual components of flavour perception to be determined.

An overview is presented of the principle, scope and major applications to date of the use of atmospheric pressure chemical ionisation mass spectrometry (APCI-MS) for monitoring the kinetics of release of flavour volatiles in real time. There are four major areas in this thesis that extend from the measurement of flavour molecular mobility in sugar solutions, to the investigation of APCI-MS as a diagnostic tool for classifying apple cultivars and predicting age of cheese. Headspace techniques are the most extensively employed techniques in food analysis to measure volatile compounds, which play a central role in the perceived quality of food. The use of APCI-MS to measure aroma headspace availability with the addition of solutes was evaluated for two sugars of differing chain lengths (fructose and fructooligosaccharide (FOS)). In vitro aroma release was investigated at equilibrium using APCI-MS. An increase in the concentration of fructose above 25 % (w /w) was shown to significantly (p < 0.05) increase the release of ethyl butyrate, ethyl acetate and benzaldehyde into the gas phase above the aqueous solutions. Proton nuclear magnetic resonance (1 H NMR) was used to investigate the nature of solvent-sugar-aroma interactions with a view to explain the differential availability of aroma volatiles in sweetened and biopolymer rich solutions. The T1 relaxation times, and diffusion coefficients, provided preliminary clues as to the interactions between water, aroma and biopolymer. In the case of in vivo measurement, aroma perception was dependent on two key factors – firstly the equilibrium gas phase concentration of the aroma compounds within the oral/ nasal cavity and secondly the dynamic interaction of the compound with food and saliva (persistence). The overall process was influenced by the properties of the flavour compounds (i.e. its hydrophobicity) and the physiological conditions of the mouth, nose and throat during consumption of the food. A comparison was made between the intensities of anisaldehyde, furaneol and guaiacol in the headspace above simple solutions of water, to demonstrate the impact of matrix on flavour release in a frozen dairy dessert. The oral and nasal persistence of aromas following swallowing samples of a model frozen dairy dessert was investigated by collecting expired air from nose and mouth over 60-seconds. The decay curves (which illustrates persistence) of volatiles in breath showed that furaneol was the most persistent aroma, due to its hydrophilic nature and low volatility, that is expressed by the vapour pressure values of the pure compound. It is presumed to interact with the nasal mucosa, thereby prolonging persistence and potentially offering a significantly different perceptual profile to the less persistent compounds (Hodgson, Parker, Linforth, & Taylor, 2004). Thus, real time APCI-MS headspace data could be used to validate mathematical modelling of flavour release (Harvey & Barra, 2003). The feasibility of APCI-MS volatile compound fingerprinting in conjunction with chemometrics as a new strategy for rapid and non-destructive food classification was demonstrated when 202 clarified monovarietal juices extracted from apples differing in their botanical and geographical origins were characterised. Partial Least Square-Linear Discriminant Analysis (PLS-LDA) gave 100 % correct classification for the categorization by cultivar. Another PLS regression model was built to interpret and predict the age of Cheddar using headspace data from GC-MS and APCI-MS. The RMSEP and R2 values for the prediction model were 3.94 and 0.85 respectively. This further established the applicability of multivariate statistical technique as a tool to monitor the quality of foodstuff. Throughout the thesis, recommendations regarding practical implications for APCI-MS analysis and applications are demonstrated and discussed.