Crystallization of waxes in sunflowerseed oil: effects of an inhibitor

The mechanism of action of a commercial inhibitor on the crystallization of waxes present in sunflowerseed oil was analyzed. The results showed the inhibitor favored nucleation, leading to a decrease in the amount of waxes available for the growth of the crystals already formed. The inhibitor decreased the crystal size, increased the number of crystals and possibly caused slower crystallization of waxes.Centro de Investigación y Desarrollo en Criotecnología de Alimento

Foaming properties of soy protein isolate hydrolysates

Tensoactive species obtained by papain hydrolysis of soy protein were characterized structurally and physicochemically, and their foam-forming and -stabilizing capacity studied. Protein structural changes upon reaction ending were correlated with functional and interfacial properties and with the behaviour thereof with varying hydrolysis degree. Two different means of halting hydrolysis -pH reduction (pH=2) and quick freezing (-18ºC), respectively- were studied. Distinct structural changes and associated functional properties were found according to reaction ending conditions. No improvement of foaming properties was found for partially-hydrolyzed isolates subject to freezing at reaction ending - with respect to the starting unhydrolyzed soy protein isolate. In contrast, pH treatment as a means of halting hydrolysis led to a significant enhancement of the foaming properties of soybean protein hydrolysates consistently for all studied hydrolysis degrees (0%, 1.8%, 2.5% and 6%).Centro de Investigación y Desarrollo en Criotecnología de Alimento

Emulsifying properties of Hydrolysates isolated from soybean protein

We have developed new surfactant agents based on hydrolyzed soybean proteins using papain, and we have studied their ability to form and stabilize emulsions. The interfacial behavior and the emulsifying properties were correlated to the structural changes that the proteins underwent. The hydrolysis reaction was stopped by dropping to pH 2 in one case, or rapidly dropping the temperature to -18ºC in the other. The structural and functional properties of the obtained products depended on the way the papain hydrolysis of the soy proteins was stopped. Hydrolysis did not have a beneficial effect on the emulsifying properties of those hydrolysates that were stopped by freezing. For all the degrees of hydrolysis we studied, the emulsifying properties of the isolates were significantly improved when the hydrolysis reaction was stopped by dropping to pH 2.Centro de Investigación y Desarrollo en Criotecnología de Alimento

Enzymatic Hydrolysis of Soy Protein Isolates : DSC study

The aim of this work was to analyze the possible use of differential scanning calorimetry (DSC) as a method to study the process of protein modifications during enzymatic hydrolysis. Results of the enzymatic hydrolysis of soy protein showed significant differences in the values of maximum deflection temperature (Tp), heat of reaction (ΔH), and width at half peak height (ΔT1/2), between DSC curves corresponding to the substrate, or zerotime of hydrolysis, and those of the hydrolysates obtained by the action of cucurbita and pomiferin enzymes. DSC curve changes mentioned were explained by the use of gel-filtration chromatography, denaturing electrophoresis and surface hydrophobicity of the hydrolysis products obtained at 30 min of reaction.Centro de Investigación y Desarrollo en Criotecnología de Alimento

Margarines: A rheological study

Time-dependent flow properties of both commercial and pilot plant-made margarines were characterized under steady shear. Flow curves were fitted to the kinetic expression = zi + a e-kit+ b e -k2t. A first-order kinetic model did not describe the observed destruction process of the margarine structure in an adequate manner. In the proposed model, two structures with different destruction rates are postulated. Each structure contributes to a part of the shear stress necessary to deform the margarine sample. The parameters "r i a and b are temperature-dependent. Decreasing temperatures produce an exponential increase of ~i, a linear increase of b and an increase of a up to a point beyond which it remains constant. A physical interpretation of the model is proposed. The role of the aqueous phase was also studied. Greater hardness was detected at higher water content. Parameter zi increased, at any selected temperature, with increasing aqueous phase content of the sample. Parameter a increased with decreasing temperatures and higher water content. On the other hand, parameter b was not affected by the amount of aqueous phase. This kinetic model could be employed to perform studies on the influence of different parameters of margarine formulation on its rheologic behaviorCentro de Investigación y Desarrollo en Criotecnología de Alimento

Rheological study of dispersions prepared with modified soybean protein isolates

Structural modifications of modified soy protein isolates (SPI) were distinguished by rheological behavior. SPI were prepared by acidic (pH 2.5) and thermal-acidic treatment without (pH 1.6) and with neutralization (pH 8.0). Dynamic properties of dispersions were determined through the variation of storage and loss moduli with frequency, and loss tangent behavior was analyzed. Changes in viscoelastic parameters with protein concentration (10–12% wt/vol) and time of heating (15–60 min) were also determined. Flow properties of dispersions were estimated through apparent viscosity and flow and consistency index measurements. Rheological behavior of dispersions was compared with those found by experiment with commercial mayonnaise, mustard, and salad dressing. The analysis of rheological parameters showed that thermally treated isolates formed dispersions with high elastic modulus and consistency index with a structure mainly stabilized by hydrophobic interactions, although no gelation process after cooling was observed. From the rheological point of view, it was deduced that thermally treated isolates could be used as ingredients in the formulation of salad dressings. The alkaline sample would be more versatile because, depending on protein concentration and thermal treatment, the consistency of its dispersions was like that in salad dressing, or similar to those of mustard and mayonnaise.Centro de Investigación y Desarrollo en Criotecnología de Alimento

Storage of commercial margarine at different temperatures

The effect of storage temperature on the consistency of commercial margarine was analyzed by viscometry, differential scanning calorimetry (DSC), microscopy at low temperature and X-ray diffraction. The results obtained show that samples harden at 13°C and soften at 4°C. The greater strength of samples was apparently associated with crystals of higher melting points. Recrystallization takes place during storage leading to more stable solid solutions with higher melting points.Centro de Investigación y Desarrollo en Criotecnología de Alimento

Movilidad intergeneracional y desigualdad económica en países desarrollados

[Resumen]: Este trabajo analiza la evidencia disponible en movilidad económica intergeneracional en educación y en ingresos en los países desarrollados y estudia cómo se relaciona la desigualdad económica con la movilidad relativa, que se refiere al grado de transmisión de la posición socioeconómica de padres a hijos. Los resultados muestran que los datos de movilidad económica presentan gran variación entre países, siendo las economías nórdicas las que más movilidad presentan, tanto en educación como en ingresos. La movilidad es más reducida en países como Estados Unidos, Italia o Portugal. Observamos también que la movilidad económica intergeneracional se muestra negativamente correlacionada con la desigualdad de ingresos, como predice la conocida como Curva del Gran Gatsby. Países como Estados Unidos o Italia, donde la desigualdad es elevada, también tienden a ser aquellos en los que mayor proporción de la situación económica de los padres es transmitida a la generación siguiente.[Abstract]: This paper analyzes the available evidence on intergenerational economic mobility in education and income in high-income economies and studies how economic inequality is related to relative mobility, which refers to the extent to which an individual's socioeconomic position is determined by his parents. The results show that data on economic mobility vary substantially across countries, with the Nordic economies being the ones with the greatest mobility in terms of both education and income. Mobility is lower in countries such as the United States, Italy or Portugal. We also observe that intergenerational economic mobility is negatively correlated with income inequality, as predicted by the Great Gatsby Curve. Countries such as the United States or Italy, where inequality is high, are also those in which a greater proportion of the parents' economic situation is transmitted to the next generation.[Resumo]: Este traballo analiza a evidencia dispoñible en mobilidade económica interxeracional en educación en ingresos nos países desenvolvidos e estudia como se relaciona a desigualdade económica coa mobilidade relativa, que se refire ao grado de transmisión da posición socioeconómica de pais a fillos. Os resultados amosan que os datos de mobilidade económica presentan gran variación entre países, sendo as economías nórdicas as que máis mobilidade presentan, tanto en educación coma en ingresos. A mobilidade é máis reducida en países coma Estados Unidos, Italia ou Portugal. Observamos tamén que a mobilidade económica interxeracional está negativamente correlacionada coa desigualdade de ingresos, como predí a coñecida como Curva do Gran Gatsby. Países como Estados Unidos ou Italia, onde a desigualdade é elevada, tamén tenden a ser aqueles nos que maior proporción da situación económica dos pais é transmitida á seguinte xeración.Traballo fin de grao (UDC.ECO). Economía. Curso 2020/2

Amaranth sprouts: a potential health promoting and nutritive natural food

Amaranth sprouts are an edible food with good nutritional qualities and potential biological activities of their proteins. The chemical composition, angiotensin converting enzyme inhibitory activity and antioxidant activity of the sprouts were determined. Sprouts showed a protein content similar to the seeds on a dry basis (16%) and a high fiber content (17%). Amaranth sprout proteins presented a capacity to inhibit angiotensin converting enzyme activity similar to other plant proteins (IC50 = 0.9 ± 0.6 mg/mL). This capacity increased after in vitro gastrointestinal digestion (IC50 = 0.26 ± 0.07 mg/mL). Besides other non protein molecules, the amaranth sprout proteins also presented ABTS+. scavenging activity (TEAC = 0.32 ± 0.05 mol/mg) that increased after in vitro gastrointestinal digestion (TEAC = 0.72 ± 0.08 mol/mg) and oxygen radical antioxidant capacity. According to these results amaranth sprouts are a nutritive food with potential health promoting properties.Centro de Investigación y Desarrollo en Criotecnología de Alimento

Influence of phospholipids on the crystallization of waxes in sunflowerseed oil

The effect of lecithins on wax crystallization in sunflowerseed oil was studied. The results showed that the presence of lecithins does not modify the nucleation stage, but decreases the crystalline size. Lecithin has a minimal effect on viscosity and does not change the wax/oil equilibrium ratio. It is proposed that the main mechanism of action of lecithin involves the partial adsorption on the surface of the wax crystals interfering with their growth.Centro de Investigación y Desarrollo en Criotecnología de Alimento