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Intestinal mucositis is an important toxic side effect of 5-fluorouracil (5-FU) treatment. Saccharomyces boulardii is known to protect from intestinal injury via an effect on the gastrointestinal microbiota. The objective of the present study was to evaluate the effect of S. boulardii on intestinal mucositis induced by 5-FU in a murine model. Mice were divided into saline, saline (control) þ 5-FU or 5-FU þ S. boulardii (16 £ 109 colony-forming units/kg) treatment groups, and the jejunum and ileum were removed after killing of mice for the evaluation of histopathology, myeloperoxidase (MPO) activity, and non-protein sulfhydryl group (mainly reduced glutathione; GSH), nitrite and cytokine concentrations. To determine gastric emptying, phenol red was administered orally, mice were killed 20 min after administration, and the absorbance of samples collected from the mice was measured by spectrophotometry. Intestinal permeability was measured by the urinary excretion rate of lactulose and mannitol following oral administration. S. boulardii significantly reversed the histopathological changes in intestinal mucositis induced by 5-FU and reduced the inflammatory parameters: neutrophil infiltration (control 1·73 (SEM 0·37) ultrastructural MPO (UMPO)/mg, 5-FU 7·37 (SEM 1·77) UMPO/mg and 5-FU þ S. boulardii 4·15 (SEM 0·73) UMPO/mg); nitrite concentration (control 37·00 (SEM 2·39) mM, 5-FU 59·04 (SEM 11·41) mM and 5-FU þ S. boulardii 37·90 (SEM 5·78) mM); GSH concentration (control 477·60 (SEM 25·25) mg/mg, 5-FU 270·90 (SEM 38·50) mg/mg and 5-FU þ S. boulardii 514·00 (SEM 38·64)mg/mg). Treatment with S. Boulardii significantly reduced the concentrations of TNF-a and IL-1b by 48·92 and 32·21% in the jejunum and 38·92 and 61·79% in the ileum. In addition, S. boulardii decreased the concentrations of chemokine (C–X–C motif) ligand 1 by 5-fold in the jejunum and 3-fold in the ileum. Interestingly, S. boulardii reduced the delay in gastric emptying (control 25·21 (SEM 2·55) %, 5-FU 54·91 (SEM 3·43)% and 5-FU þ S. boulardii 31·38 (SEM 2·80) %) and induced the recovery of intestinal permeability (lactulose:mannitol ratio: control 0·52 (SEM 0·03), 5-FU 1·38 (SEM 0·24) and 5-FU þ S. boulardii 0·62 (SEM 0·03)). In conclusion, S. boulardii reduces the inflammation and dysfunction of the gastrointestinal tract in intestinal mucositis induced by 5-FU.

Replaced with revised version of paper 11/17/06. Former title: Forecasting Food Price Inflation, Challenges for Central Banks in Developing Countries using an Inflation Targeting Framework: the Case of Colombia

Thermal processing is widely used in the food industry mainly to improve quality and safety of food products. The investigation of heat transfer problems of non-Newtonian fluids during heating and cooling in heat exchangers is of major interest since the main factor limiting heat transfer is the viscous behaviour of these fluids. Therefore, the knowledge of the interface heat transfer coefficients is important in the design of food processes and processing equipment. In the present work, simulations of stirred yoghurt cooling in a plate heat exchanger were performed using computational fluid dynamics (CFD) calculations and the obtained results were compared with experimental data. Simulations were carried out using the commercial finite element method package POLYFLOW, being the geometrical domain the representation of a single 3D channel of the plate heat exchanger with a 30º corrugation angle. The correlation obtained numerically was compared to the one obtained from previous experimental work and they were found to be very similar to the experimental one. The constitutive model, under the assumptions used, was found to be a very good approximation for predicting the convective coefficients of stirred yoghurt during cooling in a plate heat exchanger.

Research on heat transfer of non-Newtonian fluids during thermal processing is useful to optimise the heat exchanger design, as well as to define quality levels of the final product. In the present study, a nonisothermal and non-Newtonian flow in plate heat exchangers was simulated numerically, in order to evaluate the influence of corrugation angle on the thermal and hydrodynamics characteristics of yoghurt during cooling in a plate heat exchanger (PHE). Cooling treatment of stirred yoghurt is usually carried out in PHEs since these equipments are suitable for liquid-liquid heat transfer duties that require uniform and rapid cooling or heating. In this operation, two mechanisms of heat transfer occur: conduction, in the plates, and convection inside the channels. The set of equations that describe mathematically the problem were the Navier-Stokes equations, for incompressible and stationary flow, and Fourier’s law for the conduction problems. Additionally, a constitutive model that describes the rheological properties of yoghurt under the cooling conditions has to be established in order to define totally the problem. The used model was proposed by Afonso et al. (2003) and takes into account the influence of shear rate and temperature

Thermal processing and manufacturing in the food industry involves heating and cooling of highly viscous fluids. In general, these fluids exhibit complex flow patterns and are dependent on temperature, shear rate, duration of shear and elastic properties. Since the main factor limiting heat transfer is the viscous behaviour of the fluids, models that can capture this are of major interest to optimize heat exchanger design and to proper control of the manufacturing processes. A typical non-Newtonian food fluid is yoghurt, the rheological properties of which are influenced by several factors related with the physical nature of yoghurt and the processing conditions. Rheologically, stirred yoghurt shows a typical Herschel-Bulkley-type behaviour, with a yield stress at low shear rates and a power-law behaviour at higher stresses. Also, its viscosity varies from being highly temperature dependent to being almost temperature independent, depending whether it is being processed at temperatures above or below 22 ºC, respectively. The aim of the first part of this work is to simulate the non-isothermal flow of stirred yoghurt in a plate heat-exchanger. In order to do so, three problems were solved simultaneously: two of heat conduction in the plates and one on non-isothermal flow in the channel. The simulation was carried out using POLYFLOW, the geometrical domain being constituted by three three-dimensional components: superior and inferior plates and the flow channel. The corrugation of the plates was assumed to have a sinusoidal variation along the heat-exchanger.

Thermal processing and manufacturing in the food industry involves heating and cooling of highly viscous fluids. In general, these fluids exhibit complex flow patterns and are dependent on temperature, shear rate, duration of shear and elastic properties. Since the main factor limiting heat transfer is the viscous behaviour of the fluids, models that can capture this are of major interest to optimize heat exchanger design and to proper control of the manufacturing processes. A typical non-Newtonian food fluid is yoghurt, the rheological properties of which are influenced by several factors related with the physical nature of yoghurt and the processing conditions. Rheologically, stirred yoghurt shows a typical Herschel-Bulkley-type behaviour, with a yield stress at low shear rates and a power-law behaviour at higher stresses. Also, its viscosity varies from being highly temperature dependent to being almost temperature independent, depending whether it is being processed at temperatures above or below 22 ºC, respectively. The aim of the second part of this work is to compare the correlations concerning stirred yoghurt convective heat transfer, obtained from numerical approaches, to the ones obtained from previous experimental work carried out in a plate heat exchanger during the cooling stage. These correlations included both rheological and thermal aspects, taking into account the complex flow behaviour of stirred yoghurt.