Investigation of the diffusion of dyes in agar gels

An experimental set-up and a measurement technique were developed so that diffusion in model foods (gels of agar) could be visualised and quantified. The diffusion of aqueous solutions of varying concentrations of two dyes (rhodamine 6G and methylene blue) in gels of agar was followed in situ at three temperatures (30, 50, 70 °C) until equilibrium was reached. The nature of the diffusion process (in terms of the amount of dye diffused into the gel) was studied using image analysis techniques. The diffusion coefficient, D, was estimated using Fick’s second law of diffusion and found to be ∼10⁻¹⁰ m² s⁻¹. The effect of the size of the diffusing molecule, as well as that of the processing temperature on diffusion was investigated and found to be significant.     

Association of glutathione S-transferase GSTM1 and GSTT1 null genotypes with clinical outcome in epithelial ovarian cancer

Epithelial ovarian cancer is generally associated with a poor outcome, although the mechanisms that determine survival and progression-free interval (PFI) are unclear. Data from ovarian tumors showing associations between (a) null genotypes at the glutathione S-transferase GSTM1 and GSTT1 loci and expression of p53 protein and (b) outcome and expression of p53 suggest that polymorphism at these loci is a factor determining outcome. Accordingly, we have studied the association between the GSTM1 null and GSTT1 null genotypes and survival and PFI in 148 women with epithelial ovarian cancer. Although we did not find an association between individual genotypes and outcome, women with both GSTM1 null and GSTT1 null genotypes demonstrated poorer survival (P = 0.001) and reduced PFI (P = 0.003). Thus, no cases with both these genotypes survived past 42 months postdiagnosis. In contrast, 43% of the women without this combination survived beyond this time. Because response to chemotherapy is a major factor determining outcome in ovarian cancer, we also examined the data for associations between the glutathione S-transferase genotypes and response to such treatment. Thus, in 78 patients treated with chemotherapy, the combination of GSTM1 null and GSTT1 null was associated with unresponsiveness to primary chemotherapy (P = 0.004); none of the eight patients with both these genotypes responded, compared with 38 of 70 (54%) of patients with other genotype combinations. The effect of the combination of genotypes on survival and PFI was lost in a multivariate model that included response to chemotherapy as a confounding factor. This suggests that the combination of GSTM1 null/GSTT1 null is associated with outcome because of its influence on response to chemotherapy. These preliminary findings may provide a basis for the selection of patients for treatment with chemotherapeutic agents.     

Simple purification methods for an alphagalactose-specific antibody from chicken eggs

For many applications avian antibody from egg yolk (IgY) offers advantages over the well-known mammalian antibodies. Different experimental techniques for the purification of IgY from chickens immunized with an alphagalactose-containing antigen (alphaGal-trisaccharide) were compared. These included ammonium sulfate precipitation, filtration with diatomaceous earth, treatment with deoxycholate, and thiophilic and affinity chromatography. Samples were tested for overall purity, protein and lipid content, and specific activity. Evaluated on the basis of these results and the simplicity of the process, the favored purification method is ammonium sulfate precipitation of diluted egg yolk directly followed by affinity chromatography. The high lipid content of IgY preparations is greatly reduced by either thiophilic or affinity chromatography. Affinity purification of ammonium sulfate precipitated material resulted in anti-alphaGal-trisaccharide IgY preparations with approximately 1% of the original protein content but approximately 100-fold higher specific activity for the alphaGal-trisaccharide epitope.     

Multiscale texture element detection

A multiscale algorithm is described, mathematically justified, and demonstrated, which enables extraction of various sizes and shapes of texture elements from natural images without need for tuning parameters.     

Characterising the cleaning mechanisms of yeast and the implications for Cleaning In Place (CIP)

Deposition of yeast inside brewery process plant is a serious industrial problem. Investigation of the cleaning of beer fermenter deposits revealed two types of fouling; yeast foam (type A) and yeast film (type B). Rheological characterisation indicated both deposits could be mimicked in lab scale fouling experiments using yeast slurry aged for different times. Water and chemical rinsing of these deposits on a lab scale flow cell revealed three distinct cleaning phases: (i) hydration and swelling, (ii) removal in the flow by dissolution and in patches and (iii) no further removal. At 30 and 50 °C water rinsing at the flow velocities investigated could remove up to 85% of the deposit. At a water rinsing temperature of 70 °C, less deposit could be removed overall. Rheological studies indicated that increasing the temperature of the deposit generated a more elastic deposit which may decrease cleanability. Chemical cleaning using 2 wt% Advantis 210 (a NaOH base cleaning agent) eventually gave a visually clean surface at all flow velocities and temperatures. Chemical cleaning at 70 °C gave the shortest cleaning times for all flow velocities, but comparable cleaning times were observed when rinsing at 30 and 50 °C, suggesting that an increase in temperature from 30 to 50 °C might not decrease the cleaning time.     

Flow induced fibre alignment in Mycoprotein paste

The effects of extrusion and squeeze flow processing on the microstructure of Mycoprotein filamentous paste, a novel meat product alternative, are investigated. The flow induced effects are quantified in terms of fibre orientation measured by a technique of fluorescence microscopy and image analysis. Imaging of the original mycelia fibre paste showed that its microstructure is ‘isotropic’. Squeezing of the native paste does not result in any significant fibre rearrangement. This is attributed to the high fibre concentration and, thus, high level of fibre entanglement in the squeezed film, and slip at the wall. A semi-concentrated suspension of mycelia fibres in a golden syrup matrix, however, shows considerable structural rearrangement throughout. Extrusion of the native paste leads to a high degree of fibre alignment in the direction of flow with a high proportion of the fibre population (80–90%) being realigned. An Exponential-Uniform Mix distribution was successfully used to describe fibre orientation in both extrusion and squeeze flow. The results show the strong link between the microstructure of highly structured food products and the mode of processing used. They may also have important implications for the rheological testing of such structurally complex materials, as the rheological response of the material may well dependent on the way it is made to interact with the instrument.     

Modelling the behaviour of heat exchangers undergoing scaling

The similarities between two types of temperature-dependent fouling, from geothermal fluids and foods, are briefly described. A computer technique which has been used to assist the design of food plant is outlined, and its modification for use in geothermal problems described. Possible uses for the technique are demonstrated using a published model for silica scale.     

Online scenario-based task help

The authors describe scenario-based task help, a design approach for online task help that attempts to assist new users in accomplishing useful work quickly and to provide quick-reference task information for users familiar with a product. The main idea of this approach is to understand the user's goals and associated tasks, to construct scenarios reflecting these tasks, and then to map the tasks to user interactions with a product. The authors describe this approach and a prototype that demonstrates the approach