Highlights• Novel technique to monitor the movement of secondary immiscible liquid within a suspension of sucrose and sunflower oil.• Achieved using a non-invasive method using X-ray CT, through a time lapse of scans.• Movement of secondary liquid influenced by surface area to volume ratio. AbstractIn this paper, the movement of a secondary immiscible liquid when added to a suspension of hydrophilic particles in a continuous hydrophobic phase is investigated. This was achieved through an approach using high speed camera and X-ray computer tomography. These non-invasive approaches allowed the secondary liquid displacement within the suspension to be monitored on the surface level and within the suspension through a time lapse of scans.The addition of a small amount of secondary liquid to suspensions, can lead to a transition from a fluid-like to paste-like structure. The kinetics taking place and responsible for this, during both short and long term storage were investigated to better understand the mechanisms taking place. Water was added as the secondary immiscible liquid to suspensions composed of sucrose (icing sugar) and sunflower oil. Different volumes of secondary liquid were added to the suspensions. The rate of movement as well as the spreading of the secondary liquid into the suspension was calculated from the scans taken. The surface area to volume ratio was proposed as a reason for the spreading of the liquid for the smaller volume droplet being greater in comparison to the larger volume droplet.

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 ...

The aim of this study was to compare approaches commonly recommended in the literature for the improvement of the survival of probiotics in the human digestive tract. The survival of two probiotics, Lactobacillus casei and Bifi dobacterium lactis, in the presence or absence of prebiotics, maize starch, fermented milk and upon encapsulation in calcium alginate-chitosan was evaluated. While B. lactis was resistant to stomach juice, but sensitive to duodenal juice, L. casei showed an exactly opposite behaviour. In contrast to other published studies, here the overall digestive survivability of probiotics was not improved signifi cantly by prebiotics, maize starch or encapsulation. However, a signifi cant improvement of the overall survivability of B. lactis (but not L. casei) during in vitro digestion was noted in milk and fermented milk, possibly due to reduction of the activity of bile against this probiotic. Summarising, no one method could be universally recommended for the improvement of probiotic survivability. Nevertheless, this research indicated that certain probiotic characteristics, such as susceptibility to bile or acid or ability to utilise matrix components as an energy source, could be used in further research to select the most effective approaches to deliver viable cells into lower parts of the digestive tract.

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The incorporation of a small amount of secondary immiscible liquid to suspensions can lead to a shift from a fluid-like structure to a paste-like structure. This is ascribed to the higher attraction of the secondary liquid to the particles, in comparison to the continuous phase. However, visual observations on the micro-scale during both long and short term time-scales, dependant on the type of secondary immiscible liquid used are yet to be reported. In the current study, the movement of various secondary immiscible liquids (water, sucrose solutions, saturated sucrose solution and glycerol) when added to a model food suspension (sucrose particles in sunflower oil) was investigated. Dynamic X-ray computed tomography was used, as a non-invasive approach, to study the mass transfer on the micro-scale and to observe the bulk movement of sucrose within the suspension. It was found that the affinity of the secondary liquid in dissolving sucrose was the primary contributor to the secondary liquid movement, with density/gravitational effects playing a minimal role. © 2017 Elsevier Lt