How long should it be good to use for antimicrobial activity testing?
If the extracts were kept at room temperature (28°C ) & in the refrigerator 4°C?
Hi,
it should be good for couple of months. You should keep it in the dark and cold place to ensure minimal reactivity and evaporation. I would divide it in aliquots keep them in -80C if not used.
Dear Mac,
I fully agree with the answer of Mateo Glumac. To exclude possible oxidation from the air your samples/extracts better to kept under reduced oxygen (vacuum) and dark conditions. Beter to store the samples at -80 °C, however, if you don't have such possibility put them in the freezer at -18 °C, but don't forget about vacuum, otherwise your samples will become wet eventually.
Usually, we store the samples until analysis, a maximum of 10 wk.
Good luck,
Yours sincerely,
Vitalijs
Dear Mac,
It is hard to say, most probably quantitative loss of phytochemical compounds will be, however, the degree of loss mainly depends on the nature of compounds in your samples, (anthocyanins, vitamin C, phenolic acids, flavonoids, etc).
To remove air we use vacuum packaging machine.
I guess that you don't have such a machine, therefore, it will be enough if you put the sample in plastic zip-lock bags and after squeeze the air out.
Dear Vitalijs
Thanks for the answer.
I guess freeze-drying is less adverse to phytochemical compounds compared to other drying methods like shade, sun or oven drying. What do you think?
I'm not sure whether we have a vacuum packaging machine. Got to find that out. The plastic zip-lock bag is also a great idea.
You are welcome dear Mac,
Yes, you're right, better results for preserving of biologically active compounds could be achieved through the utilization of freeze-drying systems, however, in one article I found that microwave vacuum drying is found to be more gentle comparing to conventional and sublimation dryers.
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