Aydın Kestanesi

Aydın Kestanesi is a fresh chestnut produced from local ecotypes of Castanea sativa Mill. grown in Aydın province in the Aegean region of western Turkey. The European Commission entered it in the register of protected designations of origin on 24 September 2020, by Commission Implementing Regulation (EU) 2020/1321, published in Official Journal L 310. The application was submitted by Aydın Commodity Exchange (Aydın Ticaret Borsası). The EU application reference is PDO-TR-01362, with an application date of 8 September 2015. The Turkish domestic GI registration is No: 180, protected as of 7 December 2010, registered 24 November 2011.

The local ecotypes grown in the region are known as Işıklar, Sarıaşı, and Kemer. These ecotypes have been selected over generations by producers who prioritised fruit size, thin shell, and easily peelable testa — the three defining quality characteristics of the PDO.

What makes it distinct

The three most important distinctive elements of Aydın Kestanesi quality, as identified in the PDO specification and Single Document, are: size of the nut, peelability of the testa, and the low penetration of the testa into the seed. These result from both natural and human factors specific to Aydın province.

Fresh chestnut has the following characteristics: the shell is usually shiny, has a light brown colour, and can be easily peeled. The kernel has a light creamy-white colour and a soft texture. The testa does not penetrate into the kernel and can be peeled off easily. Nuts weigh a minimum of 15 grammes.

Physical and chemical properties

The following values are taken directly from the PDO specification and Single Document:

• Minimum nut weight: 15 g

• Total sugar content during harvest period: 4.5–11%

• Maximum starch content: 22%

• Total carbohydrates (sugar + starch): 24.5–32%

• Protein content: 4.0–5.5%

• Average fat content: 0.5–1.5%

Production zone

The geographical area comprises the whole territory of Aydın province where Aydın Kestanesi are cultivated between 650 and 1,500 metres altitude. Aydın Province is located between 37°-44' and 38°-08' northern latitude and 27°-23' and 28°-52' eastern longitude. All processes including planting of chestnut nursery trees, irrigation, fertilization, pruning, harvesting, maturing, and storing must take place within this geographical area.

Chestnuts grow in extensive traditional orchards on sloping, sometimes terraced ground, at a restricted density of 100 chestnut trees per hectare.

Climate and growing conditions

The annual average temperature in Aydın province is 17.6°C, with averages reaching 25–30°C between June and October. These temperatures are optimal for the blossoming of chestnut trees and for the development and maturation of Aydın Kestanesi. Temperature is particularly important during pollination and fertilization, and has a direct effect on fruit set and fruit development.

The relative humidity of the air is between 45–50% during the period of fruit development and maturation. This humidity impacts chestnut quality as the fruits create their biochemical structures during that period. The specific humidity level of Aydın province causes the shell and testa of the nuts to be thinner and more easily peeled.

The average number of rainy days in Aydın province is 80.6, with an average of 600–700 mm of rain per year, including at most two dry months. The climate is mesothermic, with long hot summers and temperate winters. This rainfall is sufficient for the nuts to reach the minimum appropriate weight of 15 g.

Due to the topographic structure of the Aegean Region, humid sea air from the Aegean Sea is carried to the land while dry air from the central eastern regions blows to the coastal areas. This prevailing wind system plays a considerable role in the development of the chestnuts, with positive effects on pollination, fertilization, and the size and thickness of the shell.

The soils of Aydın region show a low salinity rate (less than 0.015%) and a generally high lime content, presenting an ideal soil type for chestnut cultivation. Soil samples are generally loamy, poor in organic matter, with low potassium content and sufficient levels of other elements (P, Ca, Mg, Na, Fe, Zn, Mn, and Cu). The low organic matter content and balanced nitrogen levels affect the thickness of the Aydın Kestanesi testa positively, making the chestnut more easily peelable.

Harvest and pile storage

Harvest in Aydın province generally runs from early September to mid-October, varying according to ecotype. The determining sign for harvest time is that the burrs are slightly opened and the fruit's natural colour has begun to appear. Harvest is performed by beating the trees with poles, and chestnuts are typically harvested with their burrs.

After harvesting, chestnuts are collected with their burrs under the trees and stored in an environment called 'pile', covered with plants such as ferns for three to four months until mid-winter. The specification confirms that this storage practice is specific to the Aydın region. During pile storage, starch content decreases and sugar and carbohydrate content increases. The loss of moisture, colour, and brightness is minimal. Chestnuts are brought to market after removing the burrs with a haymaker machine.

Human factors

Plant breeders in Aydın have long selected and propagated genotypes with high yielding potential, developing numerous local ecotypes producing quality fruit. The chestnuts grown in the region have been selected from varieties best adapted to local conditions and displaying specific qualities of taste. This selection process has resulted in varieties with a consistently thin shell. Both generative and vegetative propagation methods are used, with budding and grafting preferred for commercial production. Local ecotypes — Sarı Aşı, Işıklar, Kemer Aşı — are used as scions.

Control and certification

The competent control authority, as listed in the EU Register Extract, is the Provincial Directorate of Agriculture and Forestry, Aydın (Adnan Menderes Mahallesi Yahya Kemal Caddesi No: 2, 09010 Aydın). The three inspection criteria — size of the nut, peelability of the testa, and penetration of the testa into the seed — are tested by AYTB Laboratuvarı Hizmetleri Anonim Şirketi, a TÜRKAK-accredited institution of the Republic of Turkey Ministry of Agriculture and Forestry.