3 research outputs found
Desgomado de aceite de salvado de arroz crudo usando ultrafiltración con membrana polimérica
Membrane technology has been gaining momentum in industrial processes, especially in food technology. It is believed to simplify processes, reduce energy consumption, and eliminate pollutants. The objective was to study the performance of polyvinylidene fluoride (PVDF) and polyethersulfone (PES) polymeric membranes in the degumming of the miscella of crude rice bran oil by using a bench-scale tangential filtration module. In addition, oil miscella filtration techniques using hexane and anhydrous ethyl alcohol solvents were compared. All membranes showed the retention of phospholipids and high flow rates. However, the best performance was observed using the 50-kDa PVDF membrane in miscella hexane solvent, with a 95.5% retention of the phosphorus concentration (by a factor of 1.4), resulting in a permeate with 29 mg·kg−1 of phosphorus and an average flow rate of 48.1 L·m−2·h−1. This technology can be used as a low-pollution, economical alternative for the de-gumming of crude rice bran oil, being effective in the removal of hydratable and non-hydratable phospholipids, resulting in oils with a low phosphorus content.La tecnologÃa de membrana ha ido ganando impulso en los procesos industriales, especialmente en tecnologÃa de los alimentos. Se piensa que simplifica los procesos, reduce el consumo de energÃa, y elimina contaminantes. El objetivo fué estudiar el rendimiento de las membranas poliméricas de fluoruro de polivinilo (PVDF) y poliétersulfona (PES) en el desgomado de miscelas de aceite de salvado de arroz crudo, mediante el uso de un módulo de filtración de escalado tangencial. Además, se compararon las técnicas de filtración de miscelas de aceite, utilizando como disolventes hexano y alcohol etÃlico anhidro. Todas las membranas mostraron retención de los fosfolÃpidos y altas tasas de flujo. Sin embargo, se observó un mejor rendimiento usando la membrana de PVDF de 50-kDa con hexano como disolvente, con una retención del 95,5% de la concentración de fósforo (por un factor de 1,4), dando como resultado un permeado con 29 mg·kg−1 de fósforo y un promedio tasa de 48,1 L·m−2·h−1 de fluido. Esta tecnologÃa se puede considerar como de baja contaminación y una alternativa económica para el desgomado de aceite de salvado de arroz crudo, siendo eficaz en la eliminación de los fosfolÃpidos hidratables y no hidratables, resultando unos aceites con un bajo contenido en fósforo
Relativistic Mean Field Model with Generalized Derivative Nucleon-Meson Couplings
The quantum hadrodynamics (QHD) model with minimal nucleon-meson couplings is
generalized by introducing couplings of mesons to derivatives of the nucleon
field in the Lagrangian density. This approach allows an effective description
of a state-dependent in-medium interaction in the mean-field approximation.
Various parametrizations for the generalized couplings are developed and
applied to infinite nuclear matter. In this approach, scalar and vector
self-energies depend on both density and momentum similarly as in the
Dirac-Brueckner theory. The Schr\"{o}diger-equivalent optical potential is much
less repulsive at high nucleon energies as compared to standard relativistic
mean field models and thus agrees better with experimental findings. The
derivative couplings in the extended model have significant effects on
properties of symmetric nuclear matter and neutron matter.Comment: 35 pages, 1 table, 10 figure