Philip W. Cox

Food grade duplex emulsions designed and stabilised with different osmotic pressures.

In this study we have investigated the production of food grade W(1)/O/W(2) duplex emulsions with salt partitioned into one water phase but not the other. Investigations were carried out with and without balancing osmotic pressures with glucose. A stable 30% primary W(1)/O emulsions containing salt could be produced with more than or equal to 2% polyglycerol polyricinoleate (PGPR) in the oil phase. We suggest that the addition of salt strengthens the interactions between surfactant molecules in the adsorbed film. This is supported by interfacial viscosity and elasticity measurements both of which increased on addition of salt and the fact that in the presence of salt the emulsion was more stable. These simple emulsions were then processed to construct duplex emulsions. When osmotic pressures were balanced with glucose there was still a release of salt in storage. The extent and rate of release was proportional to glucose concentration. This effect was followed over a period of 60days. These data suggest that the release is driven by the chemical potential difference between the two water compartments rather than the unbalanced osmotic pressures. These observations are explained in the context of a water structuring effect from the added glucose, which lowers the interfacial tension of oil-water interface and thus facilitates micellar transport of hydrated salt ions across the oil layer.

Practical food rheology : an interpretive approach

Preface. Contributors. 1 Introduction - Why the Interpretive Approach? (Niall W. G. Young). 1.1 Rheology - What is in it for me? 1.1.1 Case study. 2 Viscosity and Oscillatory Rheology (Taghi Miri). 2.1 Introduction. 2.2 Food rheology. 2.3 Directions of rheological research. 2.3.1 Phenomenological rheology or macrorheology. 2.3.2 Structural rheology or microrheology. 2.3.3 Rheometry. 2.3.4 Applied rheology. 2.4 Steady-state shear flow behaviour: viscosity. 2.4.1 Rheological models for shear flow. 2.4.2 Wall slip. 2.5 Viscoelasticity and oscillation. 2.5.1 Oscillatory testing. 2.6 Process, rheology and microstructural interactions. 2.7 Rheology of soft solids. 2.7.1 Capillary rheometer. 2.7.2 Squeeze flow rheometer. 2.8 Measuring instruments - practical aspects. 2.8.1 Choosing the right measuring system. 3 Doppler Ultrasound-Based Rheology (Beat Birkhofer). 3.1 Introduction. 3.1.1 Overview. 3.1.2 History of ultrasonic velocimetry. 3.1.3 Existing literature on UVP-based rheometry. 3.2 Ultrasound transducers. 3.3 Flow adapter. 3.3.1 Doppler angle. 3.4 Acoustic properties. 3.4.1 Propagation. 3.4.2 Attenuation. 3.4.3 Sound velocity. 3.4.4 Scattering. 3.4.5 Backscattering. 3.5 Electronics, signal processing and software. 3.5.1 Electronics. 3.5.2 Signal processing and profile estimation. 3.5.3 Software. 3.6 Pipe flow and fluid models. 3.6.1 Gradient method or point-wise rheological characterisation. 3.6.2 Power law fluid model. 3.6.3 Herschel-Bulkley fluid model. 3.6.4 Other models. 3.7 Rheometry. 3.7.1 Averaging effects at the pipe wall. 3.7.2 Fitting. 3.7.3 Gradient method. 3.8 Examples. 3.8.1 Carbopol solution. 3.8.2 Suspension of polyamide in rapeseed oil. 3.9 Summary. 4 Hydrocolloid Gums - Their Role and Interactions in Foods (Tim Foster and Bettina Wolf). 4.1 Introduction. 4.2 Behaviour of hydrocolloid gums in solution. 4.3 Hydrocolloid gelation and gel rheology. 4.4 Hydrocolloid-hydrocolloid interactions. 4.5 Hydrocolloids in foods - role and interactions. 5 Xanthan Gum - Functionality and Application (Graham Sworn). 5.1 Introduction. 5.2 Xanthan molecular structure and its influence on functionality. 5.3 The conformational states of xanthan gum. 5.4 Food ingredients and their effects on xanthan gum functionality. 5.4.1 Salts. 5.4.2 Acids (pH). 5.4.3 Xanthan and proteins. 5.4.4 Xanthan and starch. 5.5 Food processing and its impact on xanthan gum functionality. 5.5.1 Thermal treatment. 5.5.2 Homogenisation. 5.5.3 Freezing. 5.6 Food structures. 5.6.1 Emulsions. 5.6.2 Gels. 5.7 Applications. 5.8 Future trends. 6 Alginates in Foods (Alan M. Smith and Taghi Miri). 6.1 Alginate source and molecular structure. 6.2 Alginate hydrogels. 6.3 Alginic acid. 6.4 Alginate solutions. 6.5 Enzymatically tailored alginate. 6.6 Alginates as food additive. 6.6.1 Gelling agent. 6.6.2 Thickening agent. 6.6.3 Film-forming agent. 6.6.4 Encapsulation and immobilisation. 6.6.5 Texturisation of vegetative materials. 6.6.6 Stabiliser. 6.6.7 Appetite control. 6.6.8 Summary. 7 Dairy Systems (E. Allen Foegeding, Bongkosh Vardhanabhuti and Xin Yang). 7.1 Introduction. 7.2 Fluid milk. 7.2.1 Rheological properties of milk. 7.2.2 Measurements of the rheological properties of milk. 7.2.3 Factors influencing milk rheological properties. 7.2.4 Correlating rheological properties of milk to sensory perceptions. 7.2.5 Process engineering calculation. 7.3 Solid cheese. 7.3.1 Small amplitude oscillatory tests. 7.3.2 Large strain rheological analysis. 7.3.3 Creep and stress relaxation. 7.4 Rheological properties of semi-solid dairy foods. 7.4.1 Flow properties. 7.4.2 Yield stress. 7.4.3 Viscoelastic properties of semi-solid dairy products. 7.5 Effect of oral processing on interpretation of rheological measurement. 8 Relationship between Food Rheology and Perception (John R. Mitchell and Bettina Wolf). 8.1 Introduction. 8.2 Rheology and thickness perception. 8.3 Rheology and flavour perception. 8.4 Mixing, microstructure, gels and mouthfeel. 8.4.1 Mixing. 8.4.2 Microstructure. 8.4.3 Mouthfeel. 8.4.4 Gels. 8.5 Beyond shear rheology. 8.6 Conclusions. 9 Protein-Stabilised Emulsions and Rheological Aspects of Structure and Mouthfeel (Fotios Spyropoulos, Ernest Alexander K. Heuer, Tom B. Mills and Serafim Bakalis). 9.1 Introduction. 9.2 Processing and stability of emulsions. 9.2.1 Instabilities in emulsions. 9.2.2 Protein functionality at liquid interfaces. 9.2.3 Protein-stabilised oil-in-water emulsions - Effect of aqueous phase composition. 9.2.4 Effect of processing. 9.3 Oral processes. 9.3.1 Different stages and phenomena during oral processing. 9.3.2 Fluid dynamics during oral processing. 9.3.3 Interactions with saliva. 9.3.4 Interaction with oral surfaces. 9.4 In vitro measurements of sensory perception. 9.5 Future perspectives. 10 Rheological Control and Understanding Necessary to Formulate Healthy Everyday Foods (Ian T. Norton, Abigail B. Norton, Fotios Spyropoulos, Benjamin J. D. Le Reverend and Philip Cox). 10.1 Introduction. 10.2 Design and control of material properties of foods inside people. 10.2.1 Oral perception of foods. 10.2.2 Food in the stomach. 10.2.3 Food in the intestine. 10.3 Reconstructing foods to be healthy and control dietary intake. 10.3.1 Use of emulsions as partial fat replacement. 10.3.2 Duplex emulsions. 10.3.3 Fat replacement with air-filled emulsion. 10.3.4 Sheared gels (fluid gels). 10.3.5 Water-in-water emulsions. 10.3.6 Self-structuring systems. 10.4 Conclusions. References. Index.

Suspensions of air cells with cysteine-rich protein coats: Air-filled emulsions

Microbubbles have the potential to be used in many applications in different fields, especially in food, biomedical, and environmental sciences. However, to produce microbubbles with relatively long-term stability is difficult as they are inherently unstable entities. Hydrophobins are naturally occurring proteins that have previously been shown to have an ability to stabilize micron-sized air cells. More recently, small air cells with other cysteine-rich proteins such as bovine serum albumin and egg albumen (egg white protein) have been constructed using a sonochemical method. The majority of the air cells had a diameter between 1 and 10 μm. A dependence of the air cell size and stability with the processing conditions and concentration were found. The air cells’ shells are dense enough to form a cage-like structure around air cells and are equally as robust as those from hydrophobins.

Characterisation of percentage viability of Streptomyces clavuligerus using image analysis

A staining procedure has been developed to identify the different physiological states of Streptomyces clavuligerus using the fluorescent, bacterial viability stain BacLight. An image analysis method was used to quantify the extent of the differently stained regions, and therefore to measure the percentage viability. In a batch fermentation, the viability of the mycelia decreased to 64% during the rapid growth phase. Following a period of fragmentation, the viability was approximately constant at 75% until late in the fermentation, when it increased to 93%.

Improved image analysis algorithm for the characterisation of mycelial aggregates after staining

A colour image processing algorithm is presented to identify and measure morphological features of mycelial aggregates in biomass stained with crystal violet to discriminate filamentous regions and compacted cores. The method improves the accuracy and allows automation of the previous monochrome procedure (Durant et al., 1994). It has been applied to the characterisation of aggregates from a shake-flask culture of Fomes fomentarius (Basidiomycete) presenting extended filamentous outer zones. The area of the whole pellet, core, and annular regions of each pellet were measured. The convex area ratio and annular fullness were estimated and means of each samples were calculated.

Manual and semi-automated morphological analysis of Penicillium chrysogenum chemostat cultures

Measurement of key morphological indices of chemostat cultures of Penicillium chrysogenum, by image analysis, was carried out manually at Strathclyde University and semi-automatically at Birmingham University using identical preserved samples. Using both methods, the value of the mean hyphal growth unit was found to decrease with decreasing dilution rate. Although similar trends were observed for data obtained at Strathclyde and Birmingham, the values of key morphological indices measured by semi-automated analysis were consistently higher than the values obtained by manual analysis. This discrepancy was as a result of the different analysis methods, particularly with respect to clump analysis. An electronic image transfer method is discussed which would allow analysis of a given image set at either site by either method.

Decidual T Cells Exhibit a Highly Differentiated Phenotype and Demonstrate Potential Fetal Specificity and a Strong Transcriptional Response to IFN

Immune tolerance during human pregnancy is maintained by a range of modifications to the local and systemic maternal immune system. Lymphoid infiltration is seen at the implantation site of the fetal–maternal interface, and decidual NK cells have been demonstrated to facilitate extravillous trophoblast invasion into maternal decidua during the first trimester, optimizing hemochorial placentation. However, although there is considerable T cell infiltration of the maternal decidua, the functional properties of this T cell response remain poorly defined. We investigated the specificity and regulation of CD4+ and CD8+ T cells obtained from human third trimester decidua and demonstrated that decidual CD4+ and CD8+ T cells exhibit a highly differentiated effector memory phenotype in comparison with peripheral blood and display increased production of IFN-γ and IL-4. Moreover, decidual T cells proliferated in response to fetal tissue, and depletion of T regulatory cells led to an increase in fetal-specific proliferation. HY-specific T cells were detectable in the decidua of women with male pregnancies and were shown to be highly differentiated. Transcriptional analysis of decidual T cells revealed a unique gene profile characterized by elevated expression of proteins associated with the response to IFN signaling. These data have considerable importance both for the study of healthy placentation and for the investigation of the potential importance of fetal-specific alloreactive immune responses within disorders of pregnancy.

Optimal treatment of hypothyroidism associated with live birth in cases of previous recurrent placental abruption and stillbirth

To examine the clinical management of and placentas from pregnant women with hypothyroidism and obstetric history of recurrent stillbirth in order to identify possible etiologic mechanisms.