Studying model suspensions using high resolution synchrotron X-ray microtomography

Abstract

Please note that changes made in the online proofing system will be added to the article before publication but are not reflected in this PDF.We also ask that this file not be used for submitting corrections. ARTICLE IN PRESSCHERD 2506 1-17 chemical engineering research and design x x x ( 2 0 1 6 ) xxx-xxx Contents lists available at ScienceDirectChemical Engineering Research and Design j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / c h e r dStudying model suspensions using high resolution synchrotron X-ray microtomography The addition of minor quantities of secondary liquids to suspensions may lead to a transition from a fluid-like structure to paste-like structure for the system. Previous studies haveshown how rheological properties such as viscosity and yield stress are affected, however, qualitative visual observation on the micro-scale during both short and long term storage has yet to be achieved or reported.This research focuses on the movement of a secondary immiscible liquid (water or saturated sucrose solution) when added to a model food system. The model food system used in this study is a suspension of sucrose particles in a continuous oil phase to better understand the interactions between the particles and the liquid phases present. This was accomplished using dynamic X-ray computer tomography to study the behaviour of the sample. This nondestructive approach allowed the movement of the secondary liquid as well as the solid particles from the bulk suspension to be monitored through a time lapse of scans. This was achieved by observing the changes in the grey scale range of the droplet with time, which was then correlated to the uptake and movement of sucrose into the secondary liquid using an innovative method. This movement was due to the hydrophilicity and solubility of sucrose Q4with gravity/sedimentation playing a minimal role. IntroductionSeveral food products comprise of suspensions in which solid Q5 hydrophilic particles are suspended as a disperse phase throughout a continuous hydrophobic liquid phase. When a small proportion of a secondary immiscible liquid such as water or glycerol is added to a suspension of this kind, it can lead to behavioural changes from a fluid-like material to a paste-like material (Koos and Willenbacher, 2011;Johansson and Bergenståhl, 1992). This transformation has been ascribed to the formation of liquid bridges between the solid particles by the secondary liquid thereby modifying the rheological properties of the suspension such as its yield stress and viscosity which can increase several-fold Willenbacher, 2011, 2012; Koos et al., * Corresponding author. Q3E-mail address: sfislam1@sheffield.ac.uk (S.F. Islam). Negreiros et al., 2015). The secondary liquid in this case has a greater affinity to the primary particles in comparison to the continuous phase because of their hydrophilic nature. Q6 In food systems, the movement of moisture is generally considered from the view point of molecular diffusion. Moisture can enter from ...

Food suspensions study with SR microtomography

“…This was achieved using synchrotron microtomography to observe the interactions at high resolution and to monitor the dynamics of change. This work was a follow up of previous work conducted focusing on different volumes of the same secondary liquid (water) and the effect this has on the dynamics, as well as the importance of surface area to volume ratio in driving the mass transfer of sucrose from the bulk suspension [18].…”

“…This technique enabled the evolution of the system to be monitored over a set period of time. Previous work has focused on studying the mass transfer and changes in dynamics when changing the volume of secondary liquid added [18,19]. This work will concentrate on changing the secondary liquid type (in particular the sucrose concentration), on the dynamics of the system.…”

Non‐destructive characterization of pulse flours—A review

“…The authors concluded that pH strongly influences the gas diffusion between the bubbles of different milk proteins at different pHs. In another study, researchers tracked the 3D movement of a secondary immiscible liquid (water or saturated sucrose solution) when added to crystalline‐suspended sucrose in a continuous phase of sunflower oil (Islam et al., 2017). They concluded that the movement of droplets was due to the hydrophilicity and solubility of sucrose.…”

Latest advances in imaging techniques for characterizing soft, multiphasic food materials

“…As mentioned earlier, phase-contrast XCT is the preferred mode for studying low-density, multi-phasic systems such as food. By exploiting a synchrotron X-Ray source, details of the microstructures of oil/water emulsions (Nielsen et al, 2016), sucrose suspensions in oil (Hounslow et al, 2016) and ice-cream (Guo et al, 2017; samples have been obtained. All the major phases in these samples could be identified, allowing a better understanding of the spatial arrangement of all ingredients in the sample matrix.…”

“…In Hounslow et al, 2016, a model food system featuring a water droplet added to a suspension of sucrose particles in oil was studied with XCT, due to its ability to monitor simultaneously the motion of the droplet and the interactions and structural changes taking place during the experiment. The sample investigated in this work represents a model of how moisture diffusion can trigger phase transitions between fluid and pastelike material.…”