No abstract

Albumin from wheat bran was subjected to proteolysis. Molecular weight profile and particle size distribution were analyzed in the hydrolysates, which were later assayed in both crude extracts and surfaces of apple mesocarp in order to test their effect on polyphenol oxidase activity and enzymatic browning; the latter measured as L*, hue° and chroma*. Both the electrophoretic pattern and the size distribution showed, upon the hydrolysis, the appearance of aggregates with higher molecular weight than albumin. Polyphenol oxidase in crude extracts of apple was inhibited up to 40% by hydrolysates in a mixed way. The application of hydrolysates to mesocarp resulted in the impartment of a slight brownish color to the tissue and there were significant differences on L*, hue° and chroma* with respect to treatments but not with respect to time (P < 0.05). PRACTICAL APPLICATIONS The hydrolysates produced from wheat bran albumin give their color to apple tissue when applied on its surface and also inhibit apple polyphenol oxidase, so the color is maintained with time. This property could be advantageous in situations where both color imparting and control of the enzymatic browning are desirable. Important aspects to consider are: the imparted color was nice by sight and wheat bran is an inexpensive source of proteins.

A simple theoretical scheme is employed to calculate the equilibrium local concentration profile of a model suspension of highly charged colloidal particles inside a cylindrical pore in the regime corresponding to thick and narrow pores. In addition, we report results of Brownian dynamics simulations for some of the systems presented here. We have found that the local concentration profile in this geometry scales in quite a similar way as in the vicinity of a confining charged wall. ͓S1063-651X͑97͒01204-X͔ PACS number͑s͒: 82.70.Dd, 05.40.ϩj

In this work we present a study of the local structure of a model colloidal suspension highly confined inside a cylindrical pore. Such a study is based in Monte Carlo computer simulations, using the repulsive part of the Derjaguin-Landau-Verwey-Overbeek potential as the pair interaction between particles. The structural properties calculated here are the concentration profile n(rho), the axial pair correlation function g(z), and the axial-angular pair correlation function g(z,straight phi). The behavior of these quantities is analyzed as a function of the density of colloidal particles in the restricted space, and as a function of the size of the pore.

Las microalgas marinas pueden ser una fuente de moléculas bioactivas; existen numerosos reportes de actividad antioxidante, antibacteriana y antiproliferativa de extractos obtenidos a partir de macroalgas. El objetivo del presente trabajo fue evaluar la actividad citotóxica, antioxidante y antimutagénica del extracto metanólico de la microalga roja Rhodosorus marinus. El extracto fue obtenido a partir de biomasa liofilizada mediante lisis ácida y sonicación. Se evaluó la actividad citotóxica frente a 7 líneas celulares humanas con el ensayo MTT, la actividad antioxidante por ABTS y DPPH y la actividad antimutagénica con las cepas TA98 y TA100 del ensayo de Ames. Se encontró actividad citotóxica frente a 5 de las 7 líneas evaluadas. Los porcentajes de inhibición para la actividad antioxidante fueron de 25.60 + 4.03% (DPPH) y 5.59 + 0.63% (ABTS). Para el ensayo de Ames, frente a ambasm cepas probadas se alcanzaron porcentajes de inhibición de colonias revertantes de aproximadamente el 75% en la concentración más alta evaluada, lo cual indica una fuerte actividad antimutagénica. Los resultados mostraron actividad biológica en las diferentes pruebas realizadas, por lo que se infiere que el extracto metanólico contiene moléculas bioactivas de importancia en la salud y para diferentes usos biotecnológicos.