I have my leaf samples already freeze dried and stored in the silica desiccator, for some of the samples have been ground into powder and stored in glass bottles at room temperature. I am going to use these samples to measure free sugars, proline, MDA and abscisic acid, is this the proper way to store the samples?
Thanks.
Dry products are highly sensible to both water and oxygen.
So if you can you should conserved your product at low RH (ideally the same after freeze-drying treatment or lower) to avoid any anarchic rehydration.
If you can, you should preserved your leaf product under N2 to preserved it from oxidative damages.
Temperature is also a key factor (but you seems to have to conserve at room temperature).
The link below shows a work on evaluation of key parameters for the conservation of bacteria after freeze-drying.
Regards.
http://link.springer.com/article/10.1007/BF00164498
As stated in the previous answers, the dehydrated products are extremely sensitive to parameters of their immediate environment. The first is the relative humidity of the gaseous phase in which they are placed. In order to prevent the absorption of water, it is necessary to store the dried product at a relative humidity that is equal to or less than their own water activity (in general, less than 0.2). Because of their structure these granular or powdery products also provide a very large contact surface with the surrounding gas phase and this facilitates interaction with reactive oxygen species when placed in the air. Oxygen must be excluded from the gaseous phase. Note that in the presence of certain molecules (pigments ...) light is involved in the genesis of reactive oxygen species. The opacity of the containers and limited exposure to light during experiments reduce sample degradation. Even if dried, the molecules of the dehydrated product retain some mobility that promotes the development of chemical or biochemical reactions. Lowering the temperature reduces the mobility and increases the stability of freeze dried products.
Agree with all of the above, exclusion of light, fluctuations in temperature and oxygen reduced environment is best. However oxidation will occur in any vessel and is ROS production is relatively independent of temperature, but colder is better. Samples should be stored with minimum surface area exposed, i.e. not ground as this will enhance rate of oxygen uptake. All desiccation tolerant organisms will undergo slow oxidation and if not revived in time will die (i.e. resurrection plants). However, all is not lost, some wines for example get better with slow ageing and oxidation! You can of course go too far...
Good luck
kind regards
John
i have a dried oven tea leaf samples that i will later use for extraction of catechins and caffeine. i think placing in a room temperature without sunlight is the best way,isnt it?
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