English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

The kinetics of isothermal extraction of caffeine from guarana seed under the action of ultrasonic field with simultaneous cooling (UESC) was investigated. The isothermal kinetics curves were measured at temperatures range  T  = 17-58  °  C. Using the model-fitting method it was determined that the kinetics of caffeine extraction can be described by a theoretical  Jander  three-dimensional diffusional model. The values of the rate constant were calculated for different temperatures, as well as the kinetic parameters (activation energy ( E  a ) and pre-exponential factor (ln A )). Based on the results obtained, it is concluded that the rate constants of caffeine extraction under UESC are about 2 times higher in comparison to the values obtained for the extraction in the conditions of conventional heating (CH). The activation energy of the caffeine extraction under the UESCE   aUESC    =  19.4    kJ  ⋅  mol    −  1$\left( E_{\text{a}}\,^{\text{UESC}}=19.4\,\text{kJ}\cdot \text{mo}{{\text{l}}^{-1}} \right)$   is lower than the values are for CHE   aCH    =  21.8    kJ  ⋅  mol    −  1.   $\left( E_{\text{a}}\,^{\text{CH}}=21.8\,\text{kJ}\cdot \text{mo}{{\text{l}}^{-1}} \right).$   Energy consumption for UESC is four times lower than for CH conditions. It is shown that there is a linear correlation relationship between kinetic parameters obtained for UESC and CH conditions. The changes in the values of kinetic parameters are explained by the model of selective transfer of energy from the reaction system to the reactant molecules.

The kinetics of the extraction of caffeine from guarana seed under the action of ultrasonic field with simultaneous cooling