Interesterificación de fosfatidilcolina de yema de huevo y aceites vegetales catalizada por lipasas

The incorporation of polyunsaturated fatty acids into the sn-1 position of egg-yolk phosphatidylcholine (PC) in the process of lipase-catalyzed interesterification was investigated. For this purpose plant oils containing these acids in the triacylglycerol (TAG) form were used as acyl donors and three commercially available immobilized lipases were examined as biocatalysts. In all the experiments the best results were obtained using Novozym 435. After 72 h of the reaction of PC with linseed oil the maximum incorporation of α-linolenic acid into PC was 34%. The result of this reaction was also a reduction in the n-6/n-3 ratio in egg-yolk PC from 24.5 to 0.7. The highest incorporation n-6 PUFAs into PC were obtained with evening primrose oil as the acyl donor, and in this case, 50.7% of n-6 PUFA as the sum of linoleic and γ-linolenic was achieved. The highest content of γ-linolenic acid in modified PC (7.3%) was achieved in the reaction of PC with borage oil.Se ha investigado la incorporación de ácidos grasos poliinsaturados en la posición sn-1 de fosfatidilcolina de yema de huevo (PC) en el proceso de interesterificación catalizado por lipasas. Para lograr este propósito, fueron examinados aceites vegetales que contienen estos ácidos en la forma de triacilgliceroles (TAG) como donadores de acilo y tres lipasas inmovilizadas disponibles comercialmente. En todos los experimentos los mejores resultados se obtuvieron para Novozym 435. La incorporación máxima de ácido α-linolénico en PC fue del 34% después de 72h de la reacción de PC con aceite de linaza. El resultado de esta reacción fue también la reducción de la relación de n-6/n-3 en PC de yema de huevo de 24.5 a 0.7. La incorporación más alta de n-6 PUFAs en PC se logró para el aceite de onagra como donador de acilo, en este caso se alcanzó el 50.7% de n-6 PUFA, como suma de los ácidos linoleico y γ-linolénico. El mayor contenido de ácido γ-linolénico en PC modificado (7.3%) se logró en la reacción de PC con aceite de borraja

Możliwość stosowania rozkładu wielkości porów do opisu parametrów struktury porowatości betonów napowietrzonych

Air void size and number distribution constitutes a major characteristic, which substantially contributes to building up concrete resistance to cyclic freezing and thawing. The standard pore spacing factor L is based on the Powers model. Due to the assumptions made in the model, it may not be able to represent the real structure of air pores in the concrete. Consequently, it is necessary to look for other methods to describe this structure. The sought model needs to account for variability in sizes of pore chords and pore random spacing in the paste. The paper analyses the distribution type and compares porosity characteristics obtained with measurements, and on the basis of the distribution. The analysis aims to assess if it is possible to substitute chords in the 0 to 400 μm range with their distribution. Another purpose of the analysis is to compare air pore structure parameters obtained by computations on raw data with the results received on the basis of pore size distribution for a given concrete