Propolis Production

Propolis (bee glue, hive resin) is a sticky substance made when honey bees mix the resins they collect from tree buds and bark with beeswax. Bees use it to seal cracks, coat interior surfaces and make the hive easier to defend. Clean propolis is produced with a propolis screen rather than by scraping, and harvesting is made easier by freezing.

What is propolis and what do bees use it for?

A small proportion of forager bees specialise in collecting resin. The bee tears off resin with its mandibles, loads it into its pollen baskets and brings it back to the hive; there other bees take the load, work it with wax and smear it where it is needed.

• Sealing gaps: Gaps and cracks too narrow for bees to pass through (smaller than about 6 mm) are filled with propolis.
• Coating surfaces: In a natural nest, the inside of the cavity is coated with a thin layer of propolis.
• Narrowing the entrance: Before the cold season, propolis is built up around the entrance.
• Keeping the hive clean: Dead animals too large to carry out (e.g. a mouse or lizard) can be encased in propolis.

Propolis is regarded as part of the colony's collective defence; some research suggests that a thick propolis coating supports colony health. So scraping the hive walls completely clean is not always the right thing to do.

What is propolis made of?

The composition of propolis varies greatly with the source plant. Roughly half consists of resins and plant balsams, a significant part is beeswax, and the rest is essential oils, pollen and other substances. The colour can range from light yellow to reddish and dark brown.

• Temperate regions: The main source is poplar (Populus) buds; birch, alder, willow and conifers also contribute.
• Türkiye: Depending on the region, the share of poplar, chestnut, pine and other resinous trees varies; that is why propolis from different areas differs chemically.
• Tropical regions: There are types of propolis that come from entirely different plants.

The upshot: propolis is not a standard product. Recording the source plant, the area and the collection period is valuable for both quality and marketing.

How is propolis collected?

Scraping

Scraping with a hive tool from the frame lugs, top bars, crown board and box edges is the simplest way, and small amounts accumulate at every inspection. However, scraped propolis contains wax, wood shavings, paint, bee parts and dust. This product is of low quality and is often unsuitable for processing into food or supplements.

Propolis screen (trap)

The main method for clean propolis is the propolis screen: a flexible plastic sheet with narrow slots placed under the crown board, on top of the frames. The bees perceive the slots as "gaps that need sealing" and fill them with propolis. Screen propolis contains no wood or paint contamination and has a lower wax content. Types of trap, placement and harvesting details are covered on the "Propolis traps and collection" page.

Harvesting propolis: why freeze it?

At room temperature propolis is soft and sticky and will not come away from the screen. In the cold it hardens and becomes brittle. So a full screen is put into a plastic bag and kept in the freezer; then, by twisting or rubbing it, the propolis falls off in pieces. Freezing is not optional; it is part of the method.

Conditions that increase propolis production

• Season: Collection increases markedly in late summer and autumn, during preparation for winter.
• Resinous plants: The presence of poplar, chestnut and resinous trees near the apiary is decisive.
• Genetics: Some bee breeds and lines collect a lot of propolis; the Caucasian bee is known for this trait.
• Air movement and light: Bees are more eager to seal gaps through which light and air leak.
• Colony strength: Strong colonies fill the screen faster.

How is propolis cleaned and stored?

1. Sorting: Bee parts and bits of wood, metal and plastic are picked out.
2. Breaking up: It is broken or ground while cold; working with it frozen prevents sticking.
3. Packing: It is put into food-safe, airtight, preferably dark containers.
4. Storage: It is kept in a cool, dark, dry place; it keeps for a long time in the freezer. Light and heat degrade its components, and volatile substances are lost over time.

Raw propolis is mostly processed by extraction with food-grade alcohol or other solvents. This processing and its sale are subject to food legislation; a beekeeper who makes processed products must obtain the relevant permits.

How can you tell propolis quality?

• Cleanliness: It should contain no shavings, paint, bee parts or dust; screen propolis is superior in this respect.
• Wax content: Propolis with a lot of wax is pale, greasy and soft; the proportion of valuable components is lower.
• Smell: Good propolis has a sharp, resinous, aromatic smell; no smell or a mouldy smell is a sign of poor storage.
• Laboratory analysis: In commercial purchasing, criteria such as total phenolic and flavonoid content are determined by analysis; the source plant directly affects these values.

Things to watch out for: residues and allergy

• Medicine residues: Propolis retains fat-soluble substances. During mite treatment, the screen is not left in the hive and no scraping is done.
• Painted surfaces: Propolis scraped from painted or preservative-treated wood carries these substances.
• Environmental pollution: In apiaries near industry and heavy traffic, the risk of pollutants increases.
• Contact allergy: Propolis can cause contact dermatitis, which is also seen in beekeepers; people who work with propolis all the time are well advised to wear gloves.

Propolis and health

Propolis has a long history of traditional use, and its antimicrobial effects are being studied in the laboratory. However, the evidence that it prevents or treats a specific disease in humans is limited, and because its composition varies so much with the source, results cannot be generalised. The product cannot be sold with treatment claims. People with allergies, pregnant women and people taking regular medication should consult a doctor before using it.