RESUMENOleoquímica I: Estudios sobre la preparación y la estructura de los jabones de litio.Se han preparado estearato, palnnitato, miristato, laurato, caprato y caprilato de litio por fusión. Se ha realizado el análisis elemental, los espectros de absorción en el infrarrojo y las difracciones de rayos X de los Jabones de litio preparados, además del análisis termogravimétrico de los mismos.Las sales de litio anhidra de los ácidos con 12 átomos de carbono o menos mostraron una estabilidad térmica hasta los 300 ± 78 °C dependiendo de la longitud de la cadena. Por otro lado las sales con 14 átomos de carbono o más se descompusieron a 126 ± 4 °C formándose carbonato de litio.Los jabones homólogos de litio mostraron una estructura cristalina similar, siendo los enlaces metal-oxígeno del mismo tipo para los ácidos grasos de número de átomos de carbono entre 8 y 18.Sin embargo el ángulo de inclinación que forma la molécula con el plano basal aumentó con la disminución del número de átomos de carbono, lo que se observó por difracción de rayos X.Se comprobó por espectroscopia infrarroja la intensificación del carácter iónico del enlace metal-oxígeno al disminuir el número de átomos de carbono.
PALABRAS-CLAVE: Análisis elemental -Análisis termogravimétrico -Difracción de rayos X -Espectrofotometría infrarrojaHidróxido de litio -Jabón metálico.
SUMMARY Oleochemicals I: Studies on the preparation and the structure of lithium soaps.Lithium stéarate, palmitate, myristate, laurate, caprate and caprylate were prepared by means of fusion method. Elementary analysis and the infrared absorptions spectra of the prepared lithium soaps as well as their X-ray diffractions and the thermogravimetric analyses were carried out.The anhydrous lithium salts of fatty acids with 12 carbon atoms or less showed thermal stability up to ca. 300 ± 78 °C depending on the chain length. On other hand the salts with 14 carbon atoms or more were decomposed at 126 ± 4 °C leading to formation of lithium carbonate.The homologous lithium soaps had very similar crystal structure among them and their metal -to-oxygen bonds were similar for the acyl chains between 8 and 18 carbons. However the angle of inclination of the molecular axes to the basal plane increased with the decreasing of the number of carbon atoms of the fatty acid chain, as determined by X-ray diffraction. In addition, the ionic character of the metal -to-oxygen bond was enhanced with the decrease of the number of carbon atoms as shown by infrared spectroscopy.
A countercurrent extraction-isoelectric precipitation procedure for the preparation of protein isolates from defatted sunflower seed meal is described. Using 0 . 0 4~ NaOH and a solvent : meal ratio of 20 : 1, as much as 95 % of meal nitrogen was extracted.Precipitation at pH 4.0 resulted in an isolate containing 88.4% of the meal protein.Using 0.1 sodium sulphite with the alkaline solution in the countercurrent extraction resulted in a white, bland and highly pure protein isolate. Isolated sunflower seed protein is limiting in the amino acid lysine, while other essential amino acids are present in amounts which meet the dietary requirements of chicks and human adults.
Gossypol‐oil solution and colour‐fixed oil prepared therefrom are treated with ethanolamine, p‐aminobenzoic acid, urea, and acetic acid. The efficiency of the four additives in removal of gossypol and colour fixed pigments is examined. Ethanolamine and p‐aminobenzoic acid at 0.5 and 1.0% levels of the oil weight result in complete removal of gossypol and superior oil‐colour. The treated oils do not show any sign of colour reversion when subjected to conditions of accelerated storage.
Defatted sunflower-seed meal, sunflower-seed protein concentrate and protein isolate were fed to protein-depleted chicks. The effect of the enrichment of meal and of protein isolate with lysine, methionine, or a mixture of both on the nutritional value was investigated. Sunflower-seed protein products are primarily limited in lysine. Food consumption, weight gain and protein/efficiency ratio reveal superior performance of lysine- and methionine-enriched meal or protein isolate, as compared to the corresponding non-enriched products. Methionine enrichment does not improve the nutritional quality and even result in inferior performance. Non-enriched protein isolate supports better growth than non-enriched meal specially at later stages of chick growth.
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