Gemlik Zeytini
Gemlik Olive
Gemlik Zeytini is a table olive produced from O. europaea L. "Gemlik", "Gemlik 21", and "Gemlik 27" varieties grown in Gemlik, İznik, Mudanya, and Orhangazi districts of Bursa province in the southern Marmara region of Turkey. The European Commission entered it in the register of protected designations of origin on 16 June 2023, by Commission Implementing Regulation (EU) 2023/1166, published in Official Journal L 155. The Single Document was published in Official Journal C 72 on 28 February 2023. The application was submitted by Gemlik Commodity Exchange (Gemlik Ticaret Borsası) under reference PDO-TR-02618, with an application date of 10 July 2020.
The Gemlik olive is the most widely exported Turkish table olive variety. The processing method developed in Gemlik — natural brine fermentation without additives — is recognised internationally as "Gemlik-style" or "Gemlik-type" processing, a designation that originates from this geographical area.
Product description
Gemlik Zeytini is a whole table olive characterised by deep black colour, thin skin tightly adhering to the flesh, thick flesh, small roundish stone, and high oil content. The flesh is smooth, moist, and highly aromatised, separating easily from the stone. The olive is neither crushed nor damaged; defects are not tolerated.
The flesh-to-stone weight ratio is between 6/1 and 7/1 — a defining specification. Oil content is between 28% and 35%, making Gemlik Zeytini one of the highest oil-content table olive varieties in Turkey and enabling use for both table olive and olive oil production.
Size ranges between 201 and 410 fruits per kilogram. Texture as measured by olive penetrometer is between 8 and 14 kg/cm².
Chemical and physical specifications
The following values are taken directly from the specification and Single Document (OJ C 72/2023):
| Parameter | Specification | |
|---|---|---|
| Olive size | Maximum 410 fruits/kg | |
| Oil content | 28–35% | |
| Flesh/stone weight ratio | 6/1–7/1 | |
| Texture (penetrometer) | 8–14 kg/cm² | |
| Salt ratio NaCl (brine basin/tank) | Maximum 14% | |
| Salt ratio NaCl (package brine, pickled) | Maximum 8% | |
| Salt ratio NaCl (package brine, natural fermented) | Maximum 4% | |
| Size difference within batch | Maximum 4 mm | |
| Foreign matter (stems/leaves) | Maximum 3 pieces per 1 kg |
Size grades (by fruits per kg):
| Grade | Count per kg | |
|---|---|---|
| X-Large (XL) | 201–230 | |
| Large (L) | 231–260 | |
| Medium (M) | 261–290 | |
| Small (S) | 291–320 | |
| X-Small (XS) | 321–350 | |
| 2X Small (2XS) | 351–380 | |
| 3X Small (3XS) | 381–410 |
Production zone
The geographical area comprises Gemlik, İznik, Mudanya, and Orhangazi districts of Bursa province, located in the southern Marmara region of Turkey. The average altitude of the geographical area is 112 m above sea level. More than 60% of total agricultural land in the four districts is used for olive farming.
The production of unprocessed olives, processing, and packing must all take place within the delimited geographical area.
Climate and geographical factors
Bursa has a transitional climate combining features of Mediterranean and Black Sea climate — described in the specification as a special corridor between the two climate systems. This transitional character is the defining environmental factor for Gemlik Zeytini.
Olive plants require average temperatures of 15–20°C during flowering and fruit ripening and a minimum of 5°C from ripening to harvest. The average daily temperature in the geographical area is 5.8°C in January and 6.8°C in February — well suited to the required cooling period. The lowest average temperature is 16.9°C in May during flowering and 21.1°C in the fruit ripening period.
Skin characteristics: Air temperature directly affects skin thickness and adhesiveness. In warmer regions, olive fruit develops a defence mechanism by thickening its skin against high temperatures. The cooler transitional climate of Gemlik produces thin-skinned olives with skin tightly adhering to the flesh. This means consumers do not feel the skin in the mouth — a key sensory property.
Colour: Deep black colour is one of the most distinctive features of Gemlik Zeytini. Optimum day temperature for anthocyanin synthesis (which produces this colour) is 25–30°C; above 30–35°C anthocyanin synthesis decreases. The cooler Bursa climate supports consistent full black colouration.
Rainfall: The specification identifies a precise mechanism linking rainfall timing to product quality. April rainfall (average 61.8 mm, based on 1928–2021 records) promotes shoot growth and higher yield per tree. September rainfall (average 43.7 mm) promotes larger fruit size and increased oil content.
Soil: The composition is 63% clay-loam, 20% loam, and 17% clay. This soil retains water and enables olive trees to develop stronger root systems and higher yields. The sheltered bays of Gemlik and Mudanya, and the proximity of Orhangazi and İznik districts to the bay and the lake, cause olives grown and processed in these four districts to show similar quality characteristics.
Authorised varieties and cultivation
The PDO is reserved exclusively to ripe fruits of O. europaea L. "Gemlik", "Gemlik 21", and "Gemlik 27" varieties. Any other varieties mixed in during harvest may not exceed 5%. In case of new plantation, genetic material must come from the delimited area.
Plantation density must not exceed 25 trees per decare on low-slope areas and 33 trees per decare on high-slope areas.
Harvest
Olives are picked from the tree by hand, sticks, or branch-vibrated special equipment when they become fully ripe and black in colour. Where vibrated equipment is used, vibration speed must be carefully adjusted to prevent branch damage. The use of sticks is not recommended. Harvest begins in November and ends at the end of December.
Processing
Gemlik Zeytini is processed by two methods, both traditional to the area and both must take place within the geographical area:
Salamura (pickled olives, brine-cured): Olives are harvested when the flesh of the fruit has turned purple 2 mm deep to the stone. After size-grading and sorting, olives are washed and placed in concrete pools or polyethylene, polyester, or fibreglass tanks filled with potable water (12% of total olive weight). Brine concentration is 8–14% sea-salt. Olives are covered with boards and heavy stones (10–25% of total olive weight) to keep them submerged during fermentation. Under high osmotic pressure from the salt, olives are debittered and become consumable in 6–9 months. Aerated fermentation may be used to reduce this to approximately 5 months. Salinity in the tanks is checked every 2–3 days and salt added as necessary. The goal is to achieve the slightly-flat-on-both-sides shape preferred by consumers. In Gemlik-style processing, bitterness is partially leached into the brine; a slightly bitter taste with fruity flavour and weak acidity is retained in the olive.
Sele (dry-salted olives, without water): Olives are washed, graded by size, and packed in salt without water. Olives and salt (10–14% salt of total olive weight) are placed in containers in alternate layers. Direct contact with salt enables rapid penetration. Containers are turned and rolled every 2–3 days to increase contact. This phase takes at least 3–4 months. After de-bittering, the skin becomes highly wrinkled. Sele-type olives are marketed in two sub-forms: kuru sele (dry, sea-salt only) and yağlı sele (oily, with corn oil or sunflower oil added at 3–5% of olive weight in the package).
Natural fermentation without alkaline treatment applies to both methods.
Historical background
Gemlik Zeytini has been produced and traded from Bursa province for a documented long period. Ottoman Archive research has established that olives from Gemlik and Mudanya districts were produced for the Ottoman navy and palace. The Ottoman Archives contain 107 records for the Gemlik district, 86 for the Mudanya district, 13 for the Orhangazi district, and 11 for the İznik district — a body of archival evidence that confirms the product's historical commercial reputation.
The name of the processing technique — "Gemlik-style" or "Gemlik-type" processing — originates from this geographical area and has been adopted internationally to describe natural brine fermentation without additives.
Traceability system
Gemlik Commodity Exchange (GTB) has implemented a digital traceability system using QR-code labels integrated with holograms. Any stakeholder involved in production, processing, packing, or storing must notify GTB of its activity and sign a binding agreement confirming compliance with the specification. The GTB's stock-control software keeps records of all producers, traders, and packers. Scanning a QR code on a product label displays the name of the GTB, the name of the trader, and an E code (e.g. E15, E42) identifying the list of suppliers.
Control and certification
The control body named in the specification is the Gemlik Provincial Directorate of the Ministry of Agriculture and Forestry, Orhangazi Cad. No:241, Gemlik, Bursa (gemlik@tarimorman.gov.tr, +90 224 513 10 45). Note: the EU Register Extract (3/7/2026) does not list a competent control authority for this product.
Labels must include: the designation name 'Gemlik Zeytini', the trade name and address or registered mark of the producer, the European Union PDO logo, and a label integrated with the hologram, Gemlik Zeytini logo, and QR code of authenticity.
Packaging is in tin, plastic, doypack, glass, or vacuum containers.
What is the difference between salamura and sele Gemlik Zeytini?
Both are defined in the PDO specification. Salamura olives are cured in brine with sea-salt and water over 6–9 months (or approximately 5 months with aerated fermentation). They retain a slightly bitter, fruity, weakly acidic character. Sele olives are dry-salted without water over 3–4 months; their skin becomes highly wrinkled. Sele is sold as kuru sele (dry) or yağlı sele (with 3–5% corn oil or sunflower oil). Both processing methods must take place within the geographical area.
What makes Gemlik Zeytini chemically distinct from other Turkish table olives?
The terpene profile is the key chemical differentiator. The specification identifies a 4.00–5.00 ppm shift in the main terpenes (alpha-Cyclogeraniol and (E,E)-alpha-Farnesene) between the Gemlik area and other olive-growing regions. The cooler, higher-altitude transitional climate of Bursa produces lower total terpene content, which the specification links to a superior aroma profile compared to olives from warmer, lower-altitude regions. The high oil content (28–35%) also distinguishes the variety.
How does the QR traceability system work?
Each PDO label carries a QR code integrated with a hologram. Scanning the code via barcode scanner or smartphone displays the GTB's name, the trader's name, and a supplier E code identifying the producers. Labels are issued by GTB only after producers' receipts are verified against declared production volumes; excess-production warnings are generated automatically.
What documentation is required for EU import?
The combined nomenclature code confirmed in the EU Register Extract is 0709 92 (Olives, fresh or chilled). For PDO-labelled product, buyers should request a certificate of conformity from the Gemlik Provincial Directorate of Agriculture and Forestry or the Gemlik Commodity Exchange. The QR code on the label provides additional traceability documentation.
Who is the applicant institution?
Gemlik Commodity Exchange (Gemlik Ticaret Borsası — GTB), established in 1984, headquartered at Dr. Ziya Kaya Mah. Cumhuriyet Cad. No:2, Gemlik/Bursa. The exchange has 207 members including olive producer cooperatives and unions, processors, traders, exporters, warehouses, and packers.
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