Single particles accelerate final stages of capillary break up

Droplet formation of suspensions is present in many industrial and technological processes such as coating and food engineering. Whilst the finite time singularity of the minimum neck diameter in capillary break-up of simple liquids can be described by well known self-similarity solutions, the pinching of non-Brownian suspension depends in a complex way on the particle dynamics in the thinning thread. Here we focus on the very dilute regime where the filament contains only isolated beads to identify the physical mechanisms leading to the pronounced acceleration of the filament thinning observed. This accelerated regime is characterized by an asymmetric shape of the filament with an enhanced curvature that depends on the size and the spatial distribution of the particles within the capillary thread.Comment: accepted for Europhysics Letter

Dark matter and halo bispectrum in redshift space: theory and applications

We present a phenomenological modification of the standard perturbation theory prediction for the bispectrum in redshift space that allows us to extend the model to mildly non-linear scales over a wide range of redshifts, $z\leq1.5$. We find that we can describe the bispectrum of dark matter particles with $\sim5$ accuracy for $k_i\lesssim0.10\,h/{\rm Mpc}$ at $z=0$, for $k_i\lesssim0.15\,h/{\rm Mpc}$ at $z=0.5$, for $k_i\lesssim0.17\,h/{\rm Mpc}$ at $z=1.0$ and for $k_i\lesssim0.20\,h/{\rm Mpc}$ at $z=1.5$. We also test that the fitting formula is able to describe with similar accuracy the bispectrum of cosmologies with different $\Omega_m$, in the range $0.2\lesssim \Omega_m \lesssim 0.4$, and consequently with different values of the logarithmic grow rate $f$ at $z=0$, $0.4\lesssim f(z=0) \lesssim 0.6$. We apply this new formula to recover the bias parameters, $f$ and $\sigma_8$, by combining the redshift space power spectrum monopole and quadrupole with the bispectrum monopole for both dark matter particles and haloes. We find that the combination of these three statistics can break the degeneracy between $b_1$, $f$ and $\sigma_8$. For dark matter particles the new model can be used to recover $f$ and $\sigma_8$ with $\sim1$ accuracy. For dark matter haloes we find that $f$ and $\sigma_8$ present larger systematic shifts, $\sim10$. The systematic offsets arise because of limitations in the modelling of the interplay between bias and redshift space distortions, and represent a limitation as the statistical errors of forthcoming surveys reach this level. Conveniently, we find that these residual systematics are mitigated for combinations of parameters. The improvement on the modelling of the bispectrum presented in this paper will be useful for extracting information from current and future galaxy surveys. [abridged]Comment: 37 pages, 17 figures, 8 tables. Published in JCA

Effect of isolation conditions on structural properties and surface behavior of soy-whey proteins

In this study, the impact of isolation conditions on structural and surface properties at the air/water interface of soy-whey proteins (SWP) was assessed. SWP were obtained by precipitation of soy-whey (at pH 4.5 or 8.0) with acetone or ammonium sulfate. Despite the fact that all SWP samples exhibited similar electrophoretic patterns, they showed different protein content (from 54.2 to 98.2% w/w). When precipitation was performed at pH 4.5, SWP samples evidenced a decrease of protein solubility (SP) and thermal stability, while the precipitation with acetone promoted the enrichment in polysaccharides and minerals. For all samples, intrinsic fluorescence, surface hydrophobicity and Fourier transform infrared (FTIR) studies revealed structural changes correlated to protein unfolding and aggregation processes. However, the surface behavior can be predicted from these studies mainly due to differences in surface hydrophobicity and the differential contribution of insoluble aggregates. The heating of SWP samples enhanced the surface activity, regardless of the pH of the raw material and the isolation method. These results can be useful as a reference research and as a starting point for industrial exploitation of proteins from soy wastewater.Fil: Ingrassia, Romina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Física de Rosario. Universidad Nacional de Rosario. Instituto de Física de Rosario; ArgentinaFil: Sobral, Pablo Antonio. Universidad Nacional de La Plata. Facultad de Ciencias Exactas; ArgentinaFil: Risso, Patricia Hilda. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Física de Rosario. Universidad Nacional de Rosario. Instituto de Física de Rosario; ArgentinaFil: Palazolo, Gonzalo Gastón. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Investigación en Funcionalidad y Tecnología de Alimentos; ArgentinaFil: Wagner, Jorge Ricardo. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Investigación en Funcionalidad y Tecnología de Alimentos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Effects of extraction pH of chia protein isolates on functional properties

The aim of this work was to study the effect of the extraction pH on the functional properties of chia protein isolates (CPI). Samples were named as CPI10 or CPI12, according to their extraction pH, 10 or 12, respectively. Functional properties were significantly modified by the extraction pH. Color properties revealed that CPI12 presented a lower L* (47.8 ± 0.9 for CPI10 and 30 ± 1 for CPI12). Besides, a higher b* value was obtained for CPI12 (7.0 ± 0.3 for CPI12 and 5.6 ± 0.7 for CPI10), as a result of a higher ash content. CPI12 showed a higher WAC probably due to a higher exposure of polar amino acids (4.4 ± 0.1 g/g and 6.0 ± 0.2 g/g), whereas CPI10 showed a higher ability to bind oil (7.1 ± 0.2 g/g and 6.1 ± 0.2 g/g for CPI10 and CPI12, respectively). CPI10 proved more appropriate as an emulsion stabilizer than CPI12, which could be due to its higher surface hydrophobicity, protein solubility and negative net charge. The d4,3 (μm) was 29.5 ± 0.4 and 20.4 ± 0.3 in emulsions stabilized with CPI12 and CPI10, respectively. Although both isolates underwent heat gelation, they exhibited a weak gel behavior. Overall, CPI10 may be more suitable for the food industry as a meat replacer or extender.Fil: López, Débora Natalia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Departamento de Química y Física. Área Fisicoquímica; ArgentinaFil: Ingrassia, Romina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Departamento de Química y Física. Área Fisicoquímica; ArgentinaFil: Busti, Pablo Andres. Universidad Nacional de Rosario; ArgentinaFil: Wagner, Jorge Ricardo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes; ArgentinaFil: Spelzini, Darío. Universidad Nacional de Rosario; Argentina. Pontificia Universidad Católica Argentina "Santa María de los Buenos Aires"; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario; ArgentinaFil: Boeris, Valeria. Pontificia Universidad Católica Argentina "Santa María de los Buenos Aires"; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario; Argentina. Universidad Nacional de Rosario; Argentin

Rheology of cream-like emulsions prepared with soybean milk and low trans vegetable fat

The objective of this work was to study the effect of fat globule size and fat content on the rheological behavior of oil-in-water emulsions prepared with soybean milk, sunflower oil and low trans vegetable fat (LTF). Emulsions were prepared with 40 % w/w lipid phase (containing different proportions of LTF) and three different homogenization methods were used in order to obtain different globule sizes. Emulsions were subjected to controlled magnetic shaking until an increase in thickness. Partial coalescence was observed in all systems containing solid fat, which gave a rheopectic behavior and an increase in the viscoelastic parameters of the emulsions. Smaller particle sizes required higher shaking times to produce an increase in thickness, even though this did not lead to different final values of the viscoelastic parameters. The highest partial coalescence degree was observed at 50 % LTF in lipid phase, but the highest final viscoelastic parameters after shaking were observed at 100 % LTF in the lipid phase. The rheological behavior of these emulsions indicates that they could be a potential vegetable substitute for traditional dairy creams.Fil: Márquez, Andrés Leonardo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; ArgentinaFil: Wagner, Jorge Ricardo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; Argentin

Rheology of double (w/o/w) emulsions prepared with soybean milk and fortified with calcium

The objective of this work was to study the rheological behavior of water-in-oil-in-water (w/o/w) emulsions prepared with soybean milk and sunflower oil, with different calcium solutions as the internal aqueous phase, in order to evaluate them as a vegetable substitute of whipped dairy cream. The obtained systems exhibited a creamy texture, which was attributed to the swelling of w/o droplets because of the osmotic gradient generated by the inclusion of soluble salts in the internal aqueous phase. A secondary factor could be the flocculation of w/o droplets due to the interaction of released calcium with soybean proteins at the interface. Consequently, the increase of calcium chloride content produced emulsions with higher consistency. A pasteurization produced flocculation and coalescence of w/o droplets only at high calcium chloride content. These double emulsions could be a potential alternative to the whipped dairy cream, because of their texture, reduced fat content and calcium contribution.Fil: Márquez, Andrés Leonardo. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; ArgentinaFil: Wagner, Jorge Ricardo. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Insoluble soybean polysaccharides: Obtaining and evaluation of their O/W emulsifying properties

The aims of this work were to obtain different samples of insoluble soybean polysaccharides (ISPS) from defatted soy flour and to study their potential application as O/W emulsifier. In this regard, the insoluble residue (okara) resulting from an aqueous extraction (60 °C, pH 9.0), was submitted to an acidic extraction (pH 3.5, 120 °C) without or with a pretreatment (high pressure homogenization or sonication treatment). The insoluble residues of these extractions were dried (oven, 70 °C or vacuum post-treatment with 2-propanol, 40 °C) yielding different ISPS samples. Aqueous dispersions of ISPS samples (1?2% w/w, pH 3 and 7), were used to prepare coarse and fine O/W emulsions. Emulsion stability against creaming and coalescence processes, and the rheological behavior were analyzed. ISPS samples obtained by okara pretreatment and vacuum dried post-treatment with 2-propanol allow to produces emulsions with high values of flocculation degree, increasing the stability of the particle size, and allowing the formation of stronger gel-like emulsions. These pretreatments expose internal sites of the polysaccharide and protein structures, increasing their superficial hydrophobicity and, therefore, allow a strong absorption of the macromolecules at the oil-water interface and/or the formation of external layers, increasing the rigidity of the interfacial film and contributing to the formation of hydrated flocs, Also, these treatments could solubilize certain compounds in okara that would interfere negatively in the formation of the interfacial film. Particularly, sample obtained by high pressures homogenization of the okara presented the best emulsifying properties and it was not significantly affected by variations in the pH of the emulsion. The results of this research work demonstrate a high potential of application of the ISPS samples as O/W emulsifier, under acid and neutral conditions, increasing the added value of an important by-product of the soybean industry.Fil: Porfiri, María Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Investigación en Funcionalidad y Tecnología de Alimentos; ArgentinaFil: Vaccaro, J.. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Investigación en Funcionalidad y Tecnología de Alimentos; ArgentinaFil: Stortz, Carlos Arturo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Centro de Investigaciones en Hidratos de Carbono. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones en Hidratos de Carbono; ArgentinaFil: Navarro, Diego Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Centro de Investigaciones en Hidratos de Carbono. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones en Hidratos de Carbono; ArgentinaFil: Wagner, Jorge Ricardo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Investigación en Funcionalidad y Tecnología de Alimentos; ArgentinaFil: Cabezas, Dario Marcelino. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología. Laboratorio de Investigación en Funcionalidad y Tecnología de Alimentos; Argentin

Viscoelastic response of confined powder under large strain oscillations, characterized by its noise temperature

We report a study on granular matter with and without small additions of silicon oil, under low-frequency and large amplitude oscillatory shear strain under constant normal pressure, by running experiments with a rotational rheometer with a cup-and-plate geometry. We analysed the expansion with the Chebyshev polynomials of the orthogonal decomposition of stress–strain Lissajous–Bowditch loops. We found the onset of the strain amplitude for the yielding regime indicated a regime change from filament-like structures of grains to grain rearrangements for the dry granulate and from oscillations to the breaking and regeneration of liquid bridges for wet granulates. We have shown that this viscoelastic dynamics can be characterized by a noise temperature following Sollich et al. (Phys Rev Lett https://doi.org/10.1103/ PhysRevLett.78.2020, 1997). The analysis of the first harmonics of the Chebyshev expansion showed that the state of disorder of dry and wet granular matter in pre-yielding and yielding regimes involved ensembles of different inherent states; thus, each of them was governed by a different noise temperature. The higherorder harmonics of the Chebyshev expansion revealed a proportionality between the viscous nonlinearity and the variation in the elastic nonlinearity induced by the deformation, which shows the coupling between the elastic deformation and the viscous flow of mesoscopic-scale structures