Effect of pH and ionic strength on apple juice turbidity: Application of the extended DLVO theory

Benítez, Elisa Inés; Genovese, Diego Bautista; Lozano, Jorge

doi:10.1016/j.foodhyd.2006.02.007

Cited by 37 publications

(57 citation statements)

References 23 publications

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“…While the limitations of the theory are well known, [3][4][5] the theory has nevertheless provided insight across a vast range of fields, including agriculture and food science, [6][7][8] mineral and oil extraction, 9,10 and filtration 11 and biology. [12][13][14] One limitation of the theory is that it is built upon the assumption of ideally smooth surfaces.…”

Section: Introductionmentioning

confidence: 99%

Surface forces: Surface roughness in theory and experiment

Parsons

Walsh

Craig

2014

The Journal of Chemical Physics

119

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A method of incorporating surface roughness into theoretical calculations of surface forces is presented. The model contains two chief elements. First, surface roughness is represented as a probability distribution of surface heights around an average surface height. A roughness-averaged force is determined by taking an average of the classic flat-surface force, weighing all possible separation distances against the probability distributions of surface heights. Second the model adds a repulsive contact force due to the elastic contact of asperities. We derive a simple analytic expression for the contact force. The general impact of roughness is to amplify the long range behaviour of noncontact (DLVO) forces. The impact of the elastic contact force is to provide a repulsive wall which is felt at a separation between surfaces that scales with the root-mean-square (RMS) roughness of the surfaces. The model therefore provides a means of distinguishing between "true zero," where the separation between the average centres of each surface is zero, and "apparent zero," defined by the onset of the repulsive contact wall. A normal distribution may be assumed for the surface probability distribution, characterised by the RMS roughness measured by atomic force microscopy (AFM). Alternatively the probability distribution may be defined by the histogram of heights measured by AFM. Both methods of treating surface roughness are compared against the classic smooth surface calculation and experimental AFM measurement.

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Section: Introductionmentioning

confidence: 99%

Surface forces: Surface roughness in theory and experiment

Parsons

Walsh

Craig

2014

The Journal of Chemical Physics

119

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“…This layer can be associated with a diffuse layer in which the ions' concentration gradually decreases with distance from the Stern layer until it reaches equilibrium with the ion concentration in the suspending medium (this diffuse layer cannot exist in our experiments, because co-ions are not present in the medium). The extended DLVO (Derjaguin, Landau, Verwey, and Overbeek) theory which adds hydration forces to the repulsive forces between two particles explains how two particles can interact with each other according to the balance in the attractive Van der Walls forces and the repulsive (electrostatic and hydration) forces (24)(25)(26). In the completely dissociated state, electronegative CCSS are surrounded by a dense cationic layer, and the repulsive inter-particular forces are more important.…”

Section: Rheologymentioning

confidence: 99%

Impact of Physicochemical Environment on the Super Disintegrant Functionality of Cross-Linked Carboxymethyl Sodium Starch: Insight on Formulation Precautions

et al. 2014

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Abstract. The aim of this work is to improve the understanding of the physicochemical mechanisms involved in the functionality of cross-linked carboxymethyl sodium starch (CCSS) as a tablet super disintegrant (SD). The behavior and properties of this SD (medium uptake, disintegration times, particle size, and rheology) was investigated in a wetting medium of different physicochemical properties. In particular, the relative permittivity (dielectric constant) of these media was intentionally modified for evaluating its effect on CCSS properties. Results showed different swelling behaviors of CCSS particles according to the relative permittivity of the tested media and allow to propose two underlying mechanisms that explain CCSS functionality. Both the intra-particular swelling and the inter-particular repulsion are affected by the relative permittivity of the media. Finally, disintegration test performed on tablets specially formulated with mannitol (used commonly as an excipient and known to modify relative permittivity) confirmed that the functionality of CCSS and therefore the disintegration of the tablet can be altered according to the mannitol content.

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“…Cloudy apple juice is a colloidal dispersion where the continuous medium is basically a solution of pectin, sugars and malic acid, and the dispersed matter is mainly formed by cellular tissue comminuted during fruit processing (Benítez, Genovese, & Lozano, 2007;Sorrivas, Genovese, & Lozano, 2006). The light scattering of the polydisperse particles in suspension is perceived as juice turbidity (Mollov, Mihalev, Buleva, & Petkanchin, 2006).…”

Section: Introductionmentioning

confidence: 99%

“…However, this problem was considered to be non significant in cloudy apple juice, where the average particle size is usually >0.6 lm (Benítez et al, 2007;Sorrivas et al, 2006). Consequently, turbidity of apple juices studied in this work was measured using a nephelometric (instead of spectrophotometric) method.…”

Section: Introductionmentioning

confidence: 99%

“…(3) was derived for polydisperse systems of spherical particles in terms of their average volume-surface diameter D 32 . However, cloudy apple juice is a dilute colloidal dispersion of irregularly shaped, hydrated particles (Benítez et al, 2007;. The size of this type of particles is better characterized by the hydrodynamic diameter (D h ), which is determined as follows.…”

Section: Introductionmentioning

confidence: 99%

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