摘要:

Hydrocolloids are water-soluble biopolymers consisting of high molecular weight polysaccharides. For generations, these biopolymers were also termed gums or stabilizers imparting viscosity, gelification and long-term stability to food systems.

ISSN:0193-2691    

DOI:10.1080/01932699908943795

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Phosphotipase A2(PLA2)was used to hydrolyze phosphatidylcholine (PC) in microemulsions. Phase diagrams were constructed for mixtures of alcohols (C2-C6), medium chain triglycerides (tricaprylin, TC) or vegetable oils, PC and water, and areas corresponding to isotropic systems were identified. The PC hydrolysis was carried out with high yields at various PC/(TC+alcohol) compositions within the areas of isotropic systems at increasing amounts of solubilized water.

ISSN:0193-2691    

DOI:10.1080/01932699908943796

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The microemulsion phases of the Winsor system consisting of 47 wt% brine, 2 wt% sodium dodecylsulphate, 4 wt% butanol and 47 wt% toluene were investigated by means of2H NMR relaxation on the surfactant which was specifically deuterated in the α-position. The measurements were obtained at 20°C for salinities varying from 3 to 10 g NaCl / 100 ml H2O. From a simple relaxation model the transverse relaxation rates were transformed into sizes of (spherical) droplets, which were compared with the droplet sizes obtained from the sample compositions in the Winsor I and II regions. For the Winsor III region, the transverse relaxation rates could be rationalised in terms of a structural model based on a bicontinuous cubic liquid crystalline phase. Moreover, by invoking previously obtained data, we show that the dependence on salinity of the water, oil and surfactant self-diffusion coefficients can also be explained within the same framework.

ISSN:0193-2691    

DOI:10.1080/01932699908943797

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The content of each of the three components in the vapor phase from a phenethyl alcohol, - limonene - decane solution was determined from the composition of the condensed phase during controlled evaporation with turbulent gas flow, with complete removal of the vapor phase once per second and the values compared to those from vapor pressures determined at equilibrium.

ISSN:0193-2691    

DOI:10.1080/01932699908943798

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The weight loss during evaporation from an aqueous and nonaqueous microemulsion with limonene was followed gravimetrically at two different humidities. Result showed that at lower humidity the weight loss is greater for both of the systems. The weight loss is a however, higher for the aqueous counterpart.

ISSN:0193-2691    

DOI:10.1080/01932699908943799

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Intermediate compound II and III may be formed as a result of the reaction of horseradish peroxidase with H2O2. From the UV spectra, we can see that the stability of the intermediate compounds is worse in reverse micelle than that in aqueous solution. With the increase of the water content, the stability of intermediate compounds gets better, this means that the characteristic of the water in the water pool is near that of bulk water. The results of the stopped-flow experiments show that the formation rate constant and Vinitialof intermediate compound in reverse microemulsion are bigger than that in aqueous solution. However, within die longer reaction time, the disappearance of the intermediate compound appears early in reverse microemulsion than that in aqueous solution. These results are in agreement with the result of the UV experiments.

ISSN:0193-2691    

DOI:10.1080/01932699908943800

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The alkaline fading of malachite green, which is interpreted as parallel first order and second order reactions, has been studied in cetyltrimethylammonium bromide (CTAB) micellar solution at 25°C using spectrophotometry. A micellar catalytic model is proposed in this paper for constant concentration of hydroxideion. For this model, the first order and the second order rate constants in CTAB micellar phase,k1mandk2mhave been obtained.

ISSN:0193-2691    

DOI:10.1080/01932699908943801

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

This paper presents methods of determining the long-term stability of vitamin E emulsion and formation of microemulsions. Several emulsion systems formed by using anionic, zwitterionic and cationic surfactants have been studied in the presence and absence of NaCI. Several conclusions can be drawn: (1) by using UV absorption and particle size measurements, one may be able to predict the long-term stability of an emulsion or the possibility of forming a microemulsion by measuring the initial properties of an emulsion, (2) in order to form a stable vitamin E emulsion or microemulsion, the initial properties of the emulsion should have the following features : (a) the particle size is ≤ 200 nm, (b) the surfactant system has a saturation value ≥ 1 and (c) the surfactant system can dissolve a substantial amount of vitamin E without causing an increase of the emulsion droplet size and (3) the saturation value and the stability of many vitamin E emulsion systems can be increased by adding an optimum amount of NaCI.

ISSN:0193-2691    

DOI:10.1080/01932699908943802

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

A complete phase diagram was determined for the system: water, butanol, propanol, and tetramethyldioctyldisiloxane (TDDS) using refractive index and gas chromatography. The solubility limits were established by quantitative analysis and compared to the refractive index of known single-phase mixtures. The system contained three two-phase regions and one three-phase region, which separated from one large continuous single phase. The system exhibited a preferential phase stability, which inversely changed with the increase in polarity of the solution. Once a ratio of 3-1 water-propanol was obtained, the phase separation shifted from TDDS to water. The content of the amphophilic components influenced the solubility of TDDS and is reflected in the phase equilibria.

ISSN:0193-2691    

DOI:10.1080/01932699908943803

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Some examples of systems including useful ingredients as cosurfactants and cosolventsto furnish suitable microemulsions to be applicated in technological fields such as cosmetics and dermopharmaceuticals, are given For systems with ionic surfactants, the usual cosurfactant (medium chain lenght alcohol) was substituted by more skin compatible ingredients as butyl lactate, or alternatively by oleic acid and a glycol as cosolvent mixed in the aqueous phase of the system. On the other hand, for a system with an alkyl glucoside as nonionic surfactant, temperature - insensitive microemulsions was obtained also with butyl lactate as cosurfactant. Moreover, the influence that the presence of glycols as cosolvents involve on the isotropic liquid regions of such systems has been also evidenced. In conclusion, it is possible to formulate suitable microemulsions to practical applications, overcoming the traditional problems of the most of the conventional microemulsions as are the biological agressivity of the cosurfactant for ionic surfactant systems, and the temperature dependence for nonionic surfactant systems.

ISSN:0193-2691    

DOI:10.1080/01932699908943804

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor