The exact concentration of the desired extract should first be decided. The initial concentration of propolis to be extracted should not exceed 30%, due to less efficient or less complete extraction at higher concentrations. The correct quantity of propolis is weighed and the right volume of alcohol measured. It would be easier to weigh the correct quantity of alcohol since alcohol is much lighter than water. The specific gravity of pure ethanol is 0.794 as compared to 1.00 for water. For reasons of simplicity one can assume that one litre of 100 % alcohol weighs 800 g, 11 of 70% alcohol approximately 860 g, 11 of 50% alcohol approximately 900 g, and so on. Other alcohols and solvents have different specific gravities and quantity measures will vary accordingly. Therefore, weighing both the propolis and the solvent is the preferred method.
Pour the alcohol and propolis into a container, seal the top and shake briefly. Repeat the shaking once or twice a day, but otherwise leave the mixture in a warm dark place for at least three days. To achieve the best results, the propolis should be extracted for one or two weeks. Soaking for more than one week, according to some authors and for two weeks according to others, provides no additional benefits.
Some producers boil the alcohol and propolis mixtures for eight hours in order to dissolve all the resins. If the propolis contains wax, most of this will be dissolved by heating or must be removed prior to extraction. For a high quality product, however, heating should be avoided.
After one or two weeks, the liquid is filtered through a clean and very fine cloth, paper filters or cotton ball. The cloth may be folded into several layers to increase its effectiveness. A second filtration may be advantageous and if the extract can be refrigerated to less than 4 0C but not freezing, for several hours or a day until filtration, better results are achieved. The filter should also be cooled prior to use. The remains of the first filtration can be washed or soaked in alcohol again.
The filtrate should be a clear liquid, free of particles and dark brown or slightly reddish in colour. It should be kept in CLEAN, dark, airtight bottles. If dark coloured bottles are not available, the bottles should be kept in a cool dark place or wrapped with a cloth, paper or straw, to keep out light.
Ingredients for a 10% extract:
| Propolis |
1 part |
or |
100 g |
or |
1 kg |
| Alcohol |
9 parts |
|
900 g |
|
9 kg |
or any multiple thereof.
Ingredients for a 5% extract:
| Propolis |
1 part |
or |
100 g |
or |
1 kg |
| Alcohol |
19 parts |
|
1900 g |
|
19 kg |
or any multiple thereof.
Since solvents are relatively expensive, consideration should be given to preparing a more concentrated first extract (< 30%) The final extract can be diluted or further concentrated depending on its intended use. Most extracts are used with reduced solvent content, i.e. very high propolis concentration. Starting with a concentrated solution will therefore require less evaporation, however, as also extracts all compounds less efficiently.
Higher concentration of the extracts can be achieved by simply leaving the extract in an open large mouth container, suitably protected against dirt, dust and insects for a while. Most of the alcohol will evaporate at room temperature in a few hours.
Method 2: Oil extracted propolis (OEP)
Extracts prepared according to this method described by Marchenay (1977), and cited by Debuyser (1984) are less adaptable to commercialization, but present some simple ways of preparing inexpensively, small quantities of extract for internal as well as external application.
Mix 10 g of cleaned propolis with 200 ml (about 200 g) of olive or almond oil, or with 100 ml of quality linseed oil (refined food quality) or with 100 g of butter. Other edible oils can be substituted for the ones mentioned here.
Heat gently in a water bath for approximately 10 minutes to not more than 50 0C, stirring continuously. Filter and store the extract in well sealed containers in the dark. Refrigerated storage is recommended.
Method 3:
1. The very first step it to make sure you have a good propolis extract, with a know propolis extract content, or at least a good knowledge of it. If you have some hive propolis do the following:
1.1 put clean hive propolis you have inside a bowl, don't worry about the amount by now.
1.2 cover the propolis with alcohol. You can use any alcohol grade you've got.
1.3 keep this mix during 15 or 20 days aproximately, providing constant agitation. It should be in dry, cool, dark place.
1.4 after this period remove the liquid portion and let alcohol to evaporate in a large shallow vessel. The remaing paste is "almost pure" propolis extract, with a very low alcohol content. The evaporation must be done under 40oC (104 F) to make sure all propolis components are fully preserved.
2. To prepare a good tincture for varroa killing application use 17ml pure propolis extract and 83ml of 96oGL alcohol.
3. Make a 50% sugar sirup and let it cool down.
4. With the sirup and propolis extract, prepare a 2% solution, i.e., 98mL sirup and 2mL propolis extract. It is important to use cool sirup before mixing both, because otherwise propolis extract will sink to the vessel botton and separate from the sirup. Another important point to note is, higher propolis proportion has been reported as causing queen laying to slow down.
5. Some beekeepers just spread the solution over frames tops, 5mL over each frame top. Others use to spread over the brood frames, including covering bees.
Method 4:
They used production propolis to extract the extracts, on the basis of 200 g in a liter of alcohol at 96 °, they have well let macerate, filtered it, and have prepared a mixture of syrup at 10% alcoholic extract of propolis. They give 50 ml of this syrup to each hive on 1 Langstroth body, half for a hive, and double for one hive on 2 bodies Langstroth.
Method 5:
Frozen propolis samples are homogenized using a coffee mill. The homogenate powder was then suspended in 70 % ethanol, in a ratio of 1:9 (w/v) for effective extraction. The filtrate was dried in an incubator at 40°C which was achieved in 2 weeks time. The dried 70% ethanol extract was dissolved in 55% ethanol to make a 10% (w/v) stock solution of propolis. The stock solutions were stored in a refrigerator.