Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    We will mail you new results for this query: keywords==Interfacial properties
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Characterizing emulsion properties of microalgal and cyanobacterial protein isolates
Teuling, Emma ; Schrama, Johan W. ; Gruppen, Harry ; Wierenga, Peter A. - \ 2019
Algal Research 39 (2019). - ISSN 2211-9264
Critical protein concentration - Cyanobacteria - Emulsion behavior - Interfacial properties - Microalgae - Rubisco

Photosynthetic unicellular sources contain a large variety of proteins. The types of proteins vary between different microalgae and cyanobacteria. The aim was to study the effect of the variation in proteins and in non-proteinaceous components present in various unicellular protein isolates on their emulsion behavior. Algae soluble protein isolates (ASPIs, 66–77% w/w protein) of Nannochloropsis gaditana, Tetraselmis impellucida and Arthrospira (Spirulina) maxima were studied, using commercially available WPI as a reference (93% w/w protein). All protein isolates could form emulsions stable against creaming (d 3,2 0.2–0.3 μm) at pH 8.0. The amount of each ASPI needed (C cr ; on protein basis) to form these stable emulsions varied between the isolates, but was within the range of proteins from both similar (photosynthetic) sources (algae and sugar beet leaves) and other protein sources (dairy, legume and egg). Minor differences were observed in the pH dependence of flocculation amongst the ASPI stabilized emulsions. For the ASPIs, the expected correlation between interfacial and molecular properties (adsorption rate constant and ζ-potential) and the emulsion behavior (C cr and droplet size as a function of pH) was absent.

Investigating the effect of temperature on the formation and stabilization of ovalbumin foams
Delahaije, Roy J.B.M. ; Lech, Frederik J. ; Wierenga, Peter A. - \ 2019
Food Hydrocolloids 91 (2019). - ISSN 0268-005X - p. 263 - 274.
Concentration - Interfacial properties - Protein - Structural characterization - Viscosity

The effect of temperature (below denaturation temperature) on protein foam formation and stabilization is potentially large, but has received little attention. This study aims to identify the effect of temperature (15–60 °C) on ovalbumin-stabilized foams at different concentrations (0.05–50 g L−1), and place this in a theoretical perspective. With increasing temperature the initial adsorption rate (dΠ/dt) increased logarithmically from 0.006 mN m−1 s−1 at 5 °C to 0.084 mN m−1 s−1 at 60 °C. A concentration increase resulted in a linear increase of dΠ/dt. This concentration effect was also observed in the foam ability, although the foam ability increased logarithmically rather than linearly with concentration, as expected based on theory and dΠ/dt. The foam ability was hardly affected by temperature (in contrast to theory and dΠ/dt). This was attributed to the strong decrease of foam stability with increasing temperature, which was expected based on theory. At elevated temperatures, the poor foam stability interferes with the foam ability (i.e. foam stability ≈ timescale of foam formation), a situation also happening at low concentrations. When formation was faster than destabilization, the foam ability relates to the effective adsorption rate. The effective adsorption rate includes the decrease in adsorption probability with increasing surface coverage. The observed balance between the effect of adsorption rate and foam stability on foam ability is not quantitatively predictable based on current theoretical models.

Interfacial properties of green leaf cellulosic particles
Tamayo Tenorio, A. ; Gieteling, J. ; Nikiforidis, C.V. ; Boom, R.M. ; Goot, A.J. van der - \ 2017
Food Hydrocolloids 71 (2017). - ISSN 0268-005X - p. 8 - 16.
Cellulosic particles - Emulsions - Green leaves - Hemicellulose - Interfacial properties - Pickering stabilisers

Cellulosic pulp from sugar beet leaves was fractionated and assessed on its interfacial properties. After pressing leaves to express the juice, the press cake was washed at alkaline pH (pH 9) to remove residual protein, dried, milled and air classified. The obtained cellulosic particles mainly consisted of insoluble dietary fibre (77.8% w/w) with remaining proteins (6.3% w/w) and exhibited considerable interfacial activity. The protein impurities contribute to the surface charge of the particles and provide surface activity, leading to spontaneous diffusion of the particles during the interfacial tension analysis; whereas the particle adsorption kinetics were characteristic of soft particles or Pickering emulsifiers. The interfacial rheology measurements showed abnormal behaviour and unusual drop shape upon deformation, hindering interpretation of the analysis but still suggesting a rigid interface with strong physical particle-particle interactions. Stable oil-in-water emulsions were produced using cellulosic particles, and despite phase separation, the emulsions were stable against coalescence. The results suggested that mostly fine particles (0.04–1.0 μm) were responsible for the interfacial stabilisation, given the small oil droplets obtained (2–5 μm); whereas larger particles (>10 μm) created a network in the continuous phase, which was responsible for the emulsion phase separation. It was concluded that the cellulosic particles had a soft nature and suitable shape to produce stable Pickering emulsions, which can be used as food-grade particles for food and pharma applications.

Identification of critical concentrations determining foam ability and stability of β-lactoglobulin
Lech, Frederik J. ; Delahaije, Roy J.B.M. ; Meinders, Marcel B.J. ; Gruppen, Harry ; Wierenga, Peter A. - \ 2016
Food Hydrocolloids 57 (2016). - ISSN 0268-005X - p. 46 - 54.
Adsorbed amount - Interfacial properties - Protein structure - Thin liquid films - ζ-potential

To understand the properties of protein stabilized foam, quantitative parameters, such as the concentration dependence of the foam properties need to be determined. Recently, a concept was proposed that predicts the emulsifying ability (i.e. the droplet size in emulsions) based on different parameters, including the protein concentration. The aim of the present study is to investigate whether a similar concept can be applied to describe the foam ability and stability of protein stabilized foams. To achieve this, the foam, thin film and molecular properties of β-lactoglobulin (BLG) were determined at different concentrations and different pH values (pH 3-7). At each pH, a certain critical concentration for foam ability CFA, could be identified above which the set foam volume was reached, while below that value the set volume was not reached. Furthermore, for all pH another critical concentration (Ccrr32) at C > CFA was identified as the point where the bubble radius (measured at the end of foam formation) reached a minimal value. The foam ability increased with increasing pH (pH 3-7). The difference in foam ability as a function of pH was reflected in the adsorption rate (slope Π/t0.5 curve) of BLG. The foam stability increased with increasing concentration at each pH value but even in the protein rich regime where C > Ccrr32 different foam stabilities were observed, which were highest at pH 7.

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