Olive leaf extract liquid comes mainly in the form of ethanolic tinctures and water/glycerine-based liquid extracts.
This page discusses water/glycerine (glycerol) extracts, which are good general olive leaf tonics and contain no ethyl alcohol (drinking alcohol).
More about olive leaf extract ethanolic tinctures
There are a few different extraction methods each with variations used by different manufacturers resulting in a range in the quality of products.
Dried leaves are chopped/crushed and soaked in a glycerol or water/glycerol solution to extract the phytochemicals.
This is a slow process as glycerol is a weak solvent but it can be sped up by heating the mixture. This is not ideal as some
constituents can be damaged by heat and some of the volatile constituents lost.
The mixture is then pressed and filtered to obtain the liquid extract.
Once again the glycerine acts as preservative in a concentration of about 50% by volume.
A stronger ethanol-free olive leaf extract liquid can be obtained by means of a normal ethanolic extraction followed by the removal of the ethanol by distillation in a partial vacuum.
Leaves generally should not be heated above about 65deg C which means that the vacuum needed is about one half of atmospheric pressure
which will likely also remove some of the volatiles as well.
Other solvents may be used in the extraction process such as apple cider vinegar.
The quality of olive leaf extract liquid is largely determined by the care taken in the process and this can usually be determined
from the information supplied by the manufacturer.
1. Products containing good quality leaves. As this is important to the extract, suppliers of good quality leaves will promote this in their advertising material.
2. Standardised products certified to contain a specified percentage of oleuropein.
Note: Glycerol contains approximately the same energy in calories as table sugar but does not increase blood sugar levels.
More about Olive Leaf Capsules