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991.
G. N. Kramer L. De Angelis J. Pauwels W. Ooghe J. J. Belliardo 《Fresenius' Journal of Analytical Chemistry》1988,332(6):694-697
Summary The possibility of producing fruit juice reference materials is conditioned by the availability of a method which allows the transformation of the original juice or concentrate into a better physically stable form. Therefore a feasibility study of the transformation of orange juice by freeze-drying was carried out. In general, the obtained powder is hygroscopic, and tends to agglomerate into large solid lumps. Under optimal conditions of freeze-drying combined with redrying of the powder before closing the bottles, a slightly cohesive but physically stable yellow orange powder can however be obtained. Compared to the original juice, this shows no loss of reducing sugars and has a normal glucose-fructose ratio. Moreover, most aminoacids e.g. asparagine, methionine, lysine and arginine are not affected by freeze-drying. Based on the study of a limited number of important fruit juice parameters, it may be concluded that freeze-drying seems very promising in order to obtain an orange juice reference material, which after redissolution in water keeps the original chemical orange juice properties.
Gefriertrocknung von Orangensaft für die Herstellung von Referenzmaterialien相似文献
992.
993.
The eigenvalue problem of the scalar Bethe-Salpeter equation is solved by application of the vertical Dyson representation. The method of solution is developed in complete analogy to the solution of Schrödinger's equation by a Stieltjes representation in the case of a Yukawa potential. The eigenvalues are zeros of a characteristic determinant, which can be understood as a generalization of the nonrelativistic Jost function. 相似文献
994.
995.
The disappearance of significant structures in the density of states of the lower (s-like) valence bands of amorphous Group IV-semiconductors is explained as a consequence of fluctuations in second nearest neighbour positions which lead to an additional pseudopotential coefficient V(200). Silicon is treated as an example. An explanation is proposed for the different behaviour of III-V compounds, where a doublet structure of the valence band density of states occurs also in the amorphous phases. 相似文献
996.
997.
998.
The valence electron Compton profile of trigonal and polycrystalline trigonal selenium has been determined using the self-consistent OPW method. The anisotropy of the Compton profile between directions parallel and perpendicular to the c-axis is discussed. The results are compared with experimental data. The difference of the Compton profiles of the amorphous and polycrystalline phases is examined. 相似文献
999.
1000.