Thixotropic behaviour of starch, gelatin and mixed starch/gelatin gels was investigated by different rheological methods by means of the rotational viscosimeter with coaxial cylinders. Influence of different factors (gel composition, preparation temperature, gel age, homogenization and viscosimeter rotor acceleration) on the coefficients of thixotropy and parameters of the flow equation was considered. The recovery of destructed gels was followed by Doherty‐Hurd method, but also a modified method was developed and applied for determination of some specificities in the rheological behaviour of starch and gelatin gels.

Mushrooms contain many valuable compounds such as fatty acids, carbohydrates, lycopene, lovastatin, trace elements etc. As they are currently valued for biologically active substances, and as high pressure carbon dioxide fluid extraction has been documented as an effective method for preparing bioactive products from plant materials, subcritical and supercritical carbon dioxide extraction of Boletus edulis mushroom was performed. In the extracts obtained, the fatty acids were determined. Response surface methodology (RSM) was applied to investigate the effect of pressure and extraction time on the extraction yield. The analysis of variance showed that pressure and extraction time had a significant effect on the extraction yield in both investigated process. The interaction between pressure and extraction time had a significant effect only in supercritical extraction process of B. edulis. Higher extraction yields have been obtained by subcritical carbon dioxide, and higher linoleic acid content has been determined in extracts obtained by supercritical carbon dioxide.

The extraction of thyme (Thymus vulgaris L) by liquid carbon dioxide was investigated. The obtained extracts were analyzed by HPLC and GC-MS methods, and their composition was compared with that of the essential oil obtained by steam distillation and by supercritical carbon dioxide at 100 bar and 40°C. To model extraction of the thyme - liquid carbon dioxide system, we used the Reverchon - Sesti Osseo equation, as well as our modified equation

Thixotropic behavior of mixed 8% starch/gelatin gels and gel‐emulsions (8% of the sunflower oil dispersed in the starch/gelatin gel), prepared with the addition of different emulsifiers, by means of the rotational viscometer with coaxial cylinders, has been investigated. Different emulsifiers (Na‐dodecyl sulfate, cetyl alcohol, mono‐ and diglycerides of fatty acids and alkyl polyglycolethers) were applied before (at 40°C) and after (at 96°C) gelatinization of the starch. Thixotropic properties, i.e. the coefficients of thixotropy of gels and emulsions were determined by the thixotropic loop method. Samples were taken in different time intervals (up to 72 h), in order to investigate the ageing effects. Very stable gels and gel emulsions (containing carbohydrate, protein and fatty component), with high aging stability can be obtained.

No abstract