Değirmendere Hazelnut (Değirmendere Fındığı in Turkish) is an agricultural product grown in the Gölcük district of the Kocaeli province and registered by the Turkish Patent and Trademark Office as an "indication of origin." The registration date is 21.02.2025, and the file number is C2022/000262. The registrant of the product is the Gölcük District Directorate of Agriculture and Forestry. All production stages of the Değirmendere Hazelnut must be carried out within the registered geographical border.

Product Characteristics

Değirmendere hazelnut is a flat almond variety of the Corylus avellana L. species. Its shelled fruit is bright brown in color, and flat and long in shape. Its aroma is not intense; hazelnut oil taste and bitter taste are not perceived. It is a hazelnut suitable for fresh consumption.

Thanks to the Marmara Region climate characteristics of the Gölcük district and its humus-rich, clayey-loam/loamy soil structure (pH value between 5.0 and 6.5), the fruit has low fiber structure and disperses easily in the mouth when consumed. Cultivation is carried out at an altitude range of 0-31 m.

The hazelnut's fruit shape is flat from the top and bottom, and long; it widens from the base, narrows, and ends with a blunt tip. The kernel has adapted to the shape of the outer shell and is covered with a brown pellicle. The kernel's central cavity is wide. The total fat content is in the range of 60-62%. The average fruit size is 17-20 mm, kernel size is 12-14 mm, and kernel weight is 1-1.4 g. The fruit weight is in the range of 2.20-2.50 g.

Production Method

Değirmendere Hazelnut cultivation and production stages are specified below:

• Orchard/Field Establishment: It is a perennial plant with a growing period of 6-7 years. Local and ungrafted saplings (from root suckers) are used in cultivation. Sapling planting is done in an open field and generally between October 15 and November 15.
• Pruning: It begins with the shaping of saplings at planting. It is generally carried out in September and November to ensure annual shoot development and increase productivity. Root sucker cleaning is done three times a year (November, May, and June).
• Fertilization: Farm manure rich in organic matter is applied. Commercial fertilizer may also be used according to soil analysis results.
• Irrigation: It is done depending on the plant's growth periods, especially in June, July, and August. Irrigation is generally done at 6-7 day intervals and for at least 4-5 hours a day.
• Pest Control: It is mostly applied in the form of cultural control (orchard cleaning, pruning, hoeing, fertilization, and irrigation).
• Harvest: As it is produced for fresh consumption, harvesting is generally done by hand in the last week of July, and machinery is not used. Harvesting is carried out by checking the internal maturity of the fruit and while the fruit husks are green, before they dry.
• Storage: The harvested product is consumed fresh without being stored.

Geographical Border

The geographical border of the Değirmendere hazelnut is the Gölcük district of the Kocaeli province. All production stages of the product are carried out within the specified geographical border, due to its link of reputation with the geographical border.

Inspection

Inspections are carried out by an inspection authority of 4 people, under the coordination of the Gölcük District Directorate of Agriculture and Forestry. The inspection authority includes one expert each from the Gölcük District Directorate of Agriculture and Forestry, the Gölcük Chamber of Tradesmen and Craftsmen, the Halıdere Agricultural Development Cooperative, and the İhsaniye Agricultural Credit Cooperative. Inspections are conducted regularly once a year. In case of need or complaint, inspections can be carried out at any time.