water extraction of spices - (May/23/2014 )

Hello..i have a question which may sound very basic as this is my first time to use the rotary evap.

I am extracting spices with water using the rot.evap.

In a couple of papers they evaporated the solution to dryness then redissolve the concentrated extracts in water to make different concentration (mg/ml) for use. Other paper used the concentrated paste to make different concentrations for use in determining antibacterial effect. What about the water that was evaporated and collected?? I was told that it s the part that carries water soluble compounds as well from spices? Why do they use the concentrates at the end of evaporation not the collected water?

I appreciate your explanation!

Some of the ingredients are of course carried over during the concentration process with the water which depends mostly (among other) on temperature and solubility. Anyway the amounts which are carried over should be very small compared to the concentrated paste/liquid and might be negligible. If you think you need this amounts too, you could evaporate the collected water a second time. 

Thx loads! Then i understood those papers well!:) cause i was told the remaining concentrates (paste) at the end of rot.evap process are wastes!

well sometimes the evaporated solvent can be the what you want too, e.g. if you try to separate two solvents or when an ingredient which is soluble in a solvent is separated from the other stuff (which remains in the "paste"), i.e. it's a purification step then...

This depends on the actual experiment and you should ask your what your experiment is really for.

Thx for the additiknal comment. In principle i am interested in testingthe antimicrobial efficacy of the spice. Therefore after mixing and soaking in water i intend to test the essence after evaporating the water...i am not sure yet of what compounds could be there in the paste (i suppose oil??) and the remains in the collected water (am still researching in this as this is a new topic i work on). HPLC isnt included in my work and i started to question its relevance.