Physicochemical characterization of mesquite flours

[EN] Ethnic foods are healthy products interesting for the new societies. Mesquite flour offers another option for making gluten-free recipes as part of a diet for people with celiac disease. The physicochemical properties of mesquite flours (Prosopis laevigata) were characterized. The mesquite pods were dried at 60°C, 15% RH and 2 m/s airflow; then a grinding and sieving process were applied. The nutritional composition and the sorption isotherms were obtained at 30, 35, 40 and 45°C for water activities of 0.07-0.9. The particle-size distribution, morphology and thermal stability of the flours were determined by different methods.The authors are grateful to Conacyt for the scholarship granted to Larissa Reyes, and to the Instituto Politénico Nacional (Mexico) for SIP funding 20161016 and 20170755. Thanks to Dr. P. F. de Jesús Cano Barrita and M.C. Frank León Martinez for their technical assistance in the use of SEM microscope.Sandoval Torres, S.; Reyes López, L.; Méndez Lagunas, L.; Rodríguez Ramírez, J.; Barriada Bernal, G. (2018). Physicochemical characterization of mesquite flours. En IDS 2018. 21st International Drying Symposium Proceedings. Editorial Universitat Politècnica de València. 989-996. https://doi.org/10.4995/IDS2018.2018.7707OCS98999

Análisis cuantitativo de ácidos grasos en harina de Prosopis laevigata

Ripe mesquite pods are widely consumed by humans and animals in arid and semi-arid areas for their protein, carbohydrate, crude fiber and fat contents. The goal of this work is to identify and to quantify the fatty acid profile of flour from mesquite pods. Structural assignments were confirmed by the analysis of fragmentation patterns of mass spectra obtained by GC-MS. The results showed that 75% of the fatty acids were unsaturated, of which linoleic acid was predominant, while palmitic and stearic acids, and saturated fatty acids were found in minor proportions.Las vainas de mezquite maduro son ampliamente consumidas por humanos y animales en las zonas áridas y semiáridas por su contenido de proteínas, carbohidratos, fibra cruda y grasas. El propósito de este trabajo es identificar y cuantificar el perfil de ácidos grasos de harinas de vainas mezquite. La estructura química fue confirmada mediante el análisis de los fragmentos del espectro de masas obtenidos por GC-MS. Los resultados mostraron que el 75% de los ácidos grasos fueron insaturados, de los cuales, el ácido linoleico predomina mientras que el ácido pálmico y esteárico, ambos ácidos grasos saturados, fueron encontrados en menor proporción

Cathodic Stripping Voltammetry

Cathodic stripping voltammetry (CSV) is an analytical technique used for the analysis of low levels of analytes (principally trace metals and sulfur containing organic compounds) in aqueous solutions, and is based on the measurement of a reductive current response as a function of a potential scan towards more negative potentials. The technique is highly sensitive (limits of detection of 10− 10–10− 12 mol l− 1) because of the application of a preconcentrations step prior to the stripping step. During the preconcentration the analyte is collected on the surface of the working electrode (typically a mercury drop), often in the presence of an added electro-active ligand. The CSV technique has been used for automated measurements of trace metals in marine waters, but a key strength of CSV is in its use in trace metal speciation measurements in natural waters, in particular dissolved iron in marine waters

Voltammetry of L-cysteine and 2-mercaptopyridine on a self-assembled phospholipid monolayer

The redox behaviour of 2-mercaptopyridine and the aminoacid L-cysteine was studied through a self-assembled monolayer of dioleoylphosphatidylcholine adsorbed on mercury by using cyclic voltammetry. 2-Mercaptopyridine penetrates into monolayer in the zone of stability of the phospholipid layer and shows an quasi-reversible behaviour while reversibility is observed in the absence of a monolayer. This fact is reflected in the occurrence of voltammetric peaks in the above mentioned region of potentials. Conversely, cysteine was found not to penetrate in the lipid layer as long as the latter behaves like a half-membrane. Voltammetric signal of cysteine was only obtained when the potential was scanned to values positive to -0.2 V. Beyond this potential the cyclic voltammograms show a series of anodic peaks, due to a rearrangement of the lipid film and to the formation of Hg(RS)2, followed by three cathodic peaks when the scan is reversal. The behaviour of these peaks was analized

Voltammetry of 6,6'-dithiodinicotinic acid on a self-assembled phospholipid monolayer prive

This paper reports a voltammetric study of 6,6'-dithiodinicotinic acid (CPDS) across a biomimetic membrane system consisting of a monolayer of dioleoylphosphatidylcholine, deposited on mercury. Because of the low solubility of this compound and its potential decomposition in alkaline media, estimation of pK values for the carboxyl and amino groups of the pyridine ring of the CPDS entailed using the Hammett equation. UV spectra seem to confirm the presence of the dianionic form of CPDS above pH=3-4. Differential capacity and cyclic voltammetry measurements were made in order to characterize the voltammetric behavior directly on mercury and through a monolayer of dioleoylphosphatidylcholine. Estimation of the CPDS hydrophobicity degree from the partition coefficient in octanol/ water suggests no penetration of the dianion into the monolayer and supports the fact that the named dianion undergoes protonation at the phospholipid/solution interface to give a neutral specie which penetration into the phospholipid region, favored by its higher hydrophobicity, is followed by electrochemical reduction at the mercury surface