Düzce Chestnut

Düzce chestnut is a variety of chestnut obtained from the edible seeds of Castanea sativa Mill. trees, which are native to Düzce province in Türkiye and belong to the Fagaceae (beech family).

Düzce Chestnut (Ministry of Culture and Tourism) 

Distinctive Characteristics

• Size and Color: Not particularly large. The fruit husk is light brown and partially spherical, while the inner kernel is light cream-colored. The internal shrinkage rate is 5%.
• Inner Membrane Property: The inner membrane of the fruit penetrates very little into the kernel and can be easily separated from the shell. This feature provides a significant advantage in processing and consumption as kebap. It can also be consumed raw.
• Climate Influence: Düzce’s climate, which exhibits transitional characteristics between the Black Sea and Mediterranean-continental climates, offers a humid and mild environment suitable for optimal photosynthesis temperature and humidity conditions for Düzce chestnut. The region’s average relative humidity of 75% increases the fruit’s moisture content and prevents thickening of the shell. This results in a thin shell and easy separation of the inner membrane from the kernel, enabling balanced development without the need for irrigation in its natural habitat.

Physical and Chemical Properties

• Kernel weight: 3.7–8.29 g.
• Shell thickness: 0.39–0.79 mm.
• Fruit length: 19.67–27.5 mm.
• Fruit width: 21.17–29.33 mm.
• Fruit thickness: 10.67–19 mm.
• Sphericity index: Partially spherical.
• Kernel color: Light cream.
• Kernel detachment from shell: Easily separable.
• Moisutre content: 36%.
• Starch: 29.94%.
• Sugars (total): 3.26%.
• Protein: 3.34%.
• Carbohydrates: 33.2%.
• Crude fat: 0.61%.

Historical and Local Significance

• Various records documenting the presence of Anatolian chestnut in Düzce province appear in the 1899 Kastamonu Vilayet Salname and the 1915 Bolu Salname.
• Due to the high density of chestnut trees in the region, the official names of the villages Çakırhacıibrahim and Paşaormanı, under the central district of Düzce, were Kestane Köyü (Chestnut Village) prior to the 1980s.
• Markets are held twice a week in the center of Düzce province for this chestnut, also known locally as “Düzce kuzusu.”

Production Method

Düzce chestnut is obtained both from naturally growing Castanea sativa Mill. trees in the forested areas of Düzce province and through cultivation in chestnut orchards established by grafting trees of various ages.

• Grafting: Grafting is performed in April, before buds awaken, typically between the 10th and 20th of the month. Scions are taken from the previous year’s shoots. The upper portion of the cut chestnut trunk is leveled, and 3–6 scions are grafted according to trunk thickness. Scions are inserted into the bark at their pointed ends, wrapped with tape, and sealed with grafting wax if gaps remain. Chestnut production begins as early as 3 to 5 years after grafting.
• Climate and Soil Requirements: The soil for establishing a chestnut orchard must be loose, well-aerated, deep, rich in potassium, and low in lime. Deep plowing is carried out before planting, 50x50 cm pits are dug, and at least 3 tons of manure per hectare are applied. Chestnut trees are planted at a minimum spacing of 10 meters.
• Irrigation: Chestnut trees thrive in rainy and humid environments. Irrigation during dry years, particularly in July, August, and September, enhances both the quality and yield of the crop.
• Fertilization: After initial planting, well-composted farmyard manure may be applied to the trees every three years.
• Pruning: Trees are pruned to develop a broad, open canopy. After planting, all vigorous and excessive shoots are removed annually. In mature, fruit-bearing trees, pruning involves removing broken, dried, diseased, or shading branches and overcrowded shoots.

Düzce Chestnut (Ministry of Culture and Tourism)

Harvest Period and Storage

• Harvest: The harvest of Düzce chestnut typically takes place over a two-month period from the end of September to mid-November. Chestnuts are knocked from the trees onto the ground and collected by hand.

Storage

• Traditional Method: Harvested chestnuts are buried in pre-prepared pits and covered with ferns. After one month in the pits, the outer husk is removed, making them ready for sale.
• Cold Storage: Chestnuts can be stored for 3–4 months in cold storage facilities maintained at 0–2 °C and 80–90% relative humidity, inside plastic bags.

Inspection

Inspections are conducted by an inspection body composed of at least three experts from the Düzce Provincial Directorate of Agriculture and Forestry, Düzce University Faculty of Agriculture and Natural Sciences, and Düzce Chamber of Agriculture, under the coordination of the Düzce Provincial Directorate of Agriculture and Forestry. Inspections are carried out annually during the harvest season (September–November) and may also be performed whenever necessary or upon complaint. All inspection reports are submitted annually to the Turkish Patent and Trademark Office.