Next Article in Journal
Genetic Diversity Analysis of Sugar Beet Multigerm Germplasm Resources Based on SRAP Molecular Markers
Previous Article in Journal
Exogenous Calcium on Calcium Accumulation, Uptake and Utilization in Tomato
Previous Article in Special Issue
Soil and Root Responses in Hazelnut Rhizosphere to Inoculate Rhizobacteria Immobilized via JetCutter Technology
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Horticulturae
Volume 11
Issue 8
10.3390/horticulturae11080987
horticulturae-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Article

Geographical Origin Affects the Nut Traits, Bioactive Compounds, and Fatty Acid Composition of Turkish Hazelnut Cultivars (Corylus avellana L. cvs. Çakıldak, Palaz, and Tombul)

by
Haydar Kurt
1,* and
Orhan Karakaya
2,*
1
Department of Horticulture, Faculty of Agriculture, Van Yuzuncu Yil University, Van 65090, Türkiye
2
Department of Horticulture, Faculty of Agriculture, Sakarya University of Applied Sciences, Sakarya 54050, Türkiye
*
Authors to whom correspondence should be addressed.
Horticulturae 2025, 11(8), 987; https://doi.org/10.3390/horticulturae11080987 (registering DOI)
Submission received: 12 July 2025 / Revised: 9 August 2025 / Accepted: 18 August 2025 / Published: 20 August 2025
(This article belongs to the Special Issue Nature-Based Solutions (NBS) to Improve the Sustainability of Horticultural Ecosystems)
Browse Figures
Versions Notes

Abstract

Hazelnuts are valuable for human health and nutrition. They are also an economically important type of nut. This study was conducted to determine the effect of different geographical origins (Giresun, Ordu, and Samsun/Türkiye) on the nut characteristics, bioactive compounds, and fatty acid composition of three hazelnut cultivars (cvs. Çakıldak, Palaz, and Tombul). The highest nut and kernel weights and sizes were determined to be in all cultivars in Samsun. The highest kernel ratio was recorded in the Çakıldak and Palaz cultivars grown in Giresun. However, shell thickness was not affected by geographical origin. The highest levels of total phenolics and total flavonoids were recorded in all cultivars in Samsun. The antioxidant activity of the cultivars differed according to geographical origin. The highest oleic acid was found in all cultivars in Giresun, while the highest linoleic acid was observed in those grown in Ordu. Generally, the highest results in terms of other fatty acids were recorded in all cultivars in Samsun. According to the results of the principal component analysis (PCA), the cultivars grown in the Samsun region were generally related to better nut traits and phenolics, while the cultivars grown in the Giresun and Ordu regions were associated with better antioxidant activity and fatty acid composition. This study shows that the nut traits, bioactive compounds, and fatty acid composition of hazelnuts are affected by geographical differences. These results provide valuable insights for hazelnut growers and the food industry.

1. Introduction

Hazelnut (Corylus avellana L.) is one of the most important nut species, both economically and nutritionally. Globally, 1.12 million tons of hazelnuts is produced on approximately 1.1 million hectares of land. Türkiye is the leading producer, with 650 thousand tons of hazelnuts produced. Italy (102,740 t), the USA (85,460 t), Azerbaijan (75,409 t), Chile (65,646 t), and Georgia (36,900 t) are other notable producing countries [1]. In Türkiye, the Black Sea Region has optimal ecological conditions for hazelnut cultivation. Ordu, Giresun, Samsun, and Trabzon are important hazelnut production areas in the region. In these provinces, Tombul, Palaz, Çakıldak, Mincane, Foşa, and Kara are the main hazelnut cultivars that are widely grown [2,3].
In the context of environmental adaptation, studies show that hazelnut cultivars exhibit considerable variation in traits depending on their geographical origin [4,5]. The diversity of hazelnut traits affects not only their commercial viability and marketability, but also their adaptability to environmental conditions, resistance to pests, and overall sustainability in agricultural practices [6]. The morphological and biochemical traits of hazelnuts are critical for quality and processing. Traits such as nut and kernel weight, shell thickness, and kernel ratio determine their desirability in the processing industry. Cultivars with thin shells and high kernel ratios are in high demand as they increase processing efficiency and consumer preference [7]. Variations among cultivars may result from different environmental conditions and regional practices, demonstrating the direct link between genetic variation and trait expression [8].
Nutritional research has shown that the nutritional composition of hazelnuts, which is influenced by genetic and environmental factors, provides health benefits including a favorable fatty acid profile and antioxidant properties [4,9]. The fatty acid composition of hazelnuts is predominantly oleic acid, representing a significant proportion of the total. Studies show that the oleic acid content ranges from 78.1% to 84.7%, with linoleic acid present at levels between 5.35% and 14% [10]. Research indicates that hazelnuts are an excellent source of monounsaturated fatty acids (MUFAs), which support cardiovascular health [11]. Additionally, the fat content of hazelnuts varies from 57.2% to 63.2%, depending on the variety [12]. The lipid content of hazelnuts plays a vital role in determining their health properties, as these fats are typically composed of triacylglycerols that encapsulate beneficial fatty acids. Beyond oleic and linoleic acids, the presence of other fatty acids, such as palmitic and stearic acids, although in small amounts, contributes to the overall nutritional profile [13].
The bioactive compound of hazelnuts enhances their nutritional value even further. They are rich in tocopherols (vitamin E) and phenolic compounds, which possess potent antioxidant properties and may help to alleviate oxidative stress and related diseases [13,14]. The presence of various phenolic acids increases antioxidant capacity, and this can vary depending on ecological conditions such as sunlight exposure. For instance, exposure to full sunlight was reported to increase the total phenolic content and antioxidant activity of hazelnuts, thereby enhancing their nutritional value [15].
Numerous factors—including variety, geographical origin, cultivation conditions, farming system, nut maturity, product load, storage conditions, and biotic or abiotic stressors—affect the hazelnut’s nut traits, bioactive content, and fatty acid composition [16,17,18]. Several studies have revealed that geographical origin causes changes in these characteristics in various fruit species [4,19,20]. In this sense, geographical differences and cultivation conditions influence the bioactive content and fatty acid composition of fruits, highlighting the importance of selecting suitable cultivation regions to enhance nutritional value [21]. While many studies have addressed the effects of geographical origin on the physical and nutritional properties of fruits, research focusing on hazelnuts in this context remains limited [4,5,22].
The aim of this study was to investigate how regional differences affect the nut characteristics, bioactive contents, and fatty acid composition of important Turkish hazelnut cultivars (Çakıldak, Palaz, and Tombul). To date, no studies have been found that investigate the effect of geographical origin on the nut characteristics, bioactive compounds, and fatty acid composition of these cultivars.

2. Materials and Methods

2.1. Plant Materials

The study was conducted in Giresun, Ordu, and Samsun provinces in the Black Sea Region of Türkiye, over two consecutive growing seasons, in 2019 and 2020 (Figure 1). The material of the study consisted of three of Türkiye’s leading hazelnut cultivars: Çakıldak, Palaz, and Tombul.
The experimental orchards were established according to the ‘Ocak’ (multi-stemmed bush; 8–10 stems per ‘Ocak’) training system. During the study period, all standard cultural practices, including pruning, fertilization, weed control, harvesting, and pest management, were performed regularly, except irrigation. Depending on the experimental orchards, a total of 500–650 g nitrogen (N), 250–350 g monoammonium phosphate (NH4H2PO4), and 100–150 g potassium sulfate (K2SO4) were applied per hectare. During the growing season, no signs of nutrient deficiency were observed in the leaves or fruit. The powdery mildew, nut weevil, and green shield bug diseases and pests were effectively controlled. Weeding was carried out twice a year before harvest. In the winter season, branch thinning was performed, and suckering was conducted once during the vegetation period.
The soils of the Giresun region are clayey–loamy, acidic, salt-free, and lime-free. They contain moderate levels of organic matter. The elevation of Giresun province is 10 m. The Ordu region has similar soil characteristics [23]. The elevation of Ordu province is 5 m. The Samsun region has clayey, slightly alkaline, salt-free, low-lime, and medium-organic matter content soils [17]. The elevation of Samsun province is 20 m.
Temperature and rainfall data for the study areas are presented in Figure 2 and Figure 3.

2.2. Experimental Design

The orchards in which the experiment was conducted had similar characteristics. The experiment was designed according to the completely randomized block design (CRBD). In each block, three replications of each cultivar and three ‘Ocaks’ (multi-stemmed bush) in each replication were selected (a total of 27 ‘Ocaks’ per cultivar).
At harvest time (10–15 August for Palaz and Tombul, and 25–30 August for Çakıldak), approximately 300 g of fruit were collected from each ‘Ocak’. The samples were harvested in the same year and at the same stage of ripeness (when the husk begins to turn yellow and the nut turns brown). Samples were collected randomly from all over the ‘Ocaks’. The harvested fruits were separated from the husks and dried naturally in the shade until the moisture content dropped to 6%. The dried samples were then stored under ambient conditions (22–24 °C and 70–80% RH) until analysis.

2.3. Nut Traits

In each replicate, 30 fruits were used for nut characteristics. Nut weight (g) and kernel weight (g) were determined using a digital balance (Radwag, Radom, Poland) with a precision of 0.01 g. Shell thickness (mm) and nut and kernel dimensions (width, length, and thickness) (mm) were measured with a digital caliper (Mitutuyo, Kawasaki, Japan) with an accuracy of 0.01 mm. Nut and kernel sizes (mm) were calculated as the geometric mean of the nut and kernel dimensions. The kernel ratio (%) was calculated as the ratio of kernel weight to nut weight and expressed as % [24].

2.4. Sample Preparation of Bioactive Compounds

Defatted hazelnut samples were used to analyze the bioactive compounds. In kernels, defatting was performed according to the Soxhlet extraction method [25]. One gram of the defatted hazelnut sample was weighed, then 10 mL of methanol was added. The solution was then centrifuged at 15,000 rpm for 20 min at 4 °C.

2.5. Total Phenolics

Total phenolic content was determined by modifying the method of Karakaya [22]. In total, 800 µL of the prepared fruit extract solution was taken and 3.7 mL of distilled water, 100 µL of Folin reagent, and 300 µL of sodium carbonate (Na2CO3) were added. After incubating for two hours, the samples were read at 760 nm using a spectrophotometer (Shimadzu, Kyoto, Japan). The obtained absorbance values were calculated as gallic acid equivalents (mg GAE g−1 dry weight).

2.6. Total Flavonoids

Total flavonoids were determined using the method described by Balta et al. [17]. In total, 1000 µL of the fruit extract was taken and made up to 4.3 mL with methanol. Then, 100 µL each of aluminum nitrate and ammonium acetate was added to the samples. After an incubation period of 30 min, the samples were read at a wavelength of 415 nm in a spectrophotometer. The results obtained were expressed as quercetin equivalents (mg QE kg−1 dry weight).

2.7. Antioxidant Activity (AA)

2.7.1. DPPH

Antioxidant activity according to DPPH test was determined by modifying the method of Blois [26]. First, a 100 µL sample of the prepared fruit extract was taken and then 2.9 mL of ethanol and 1 mL of DPPH solution (0.26 mM) were added. After incubation for 30 min, the samples were read at 517 nm using a spectrophotometer (Shimadzu, Kyoto, Japan). The results were expressed as Trolox equivalent mmol TE kg−1 dry weight.

2.7.2. FRAP

For the FRAP test, 30 µL of the fruit extract was taken and made up to 1220 µL with phosphate buffer. Then, 1.25 mL of potassium ferric cyanide was added to the samples. The samples were incubated in a water bath at 50 °C for 20 min. After incubation, 1.25 mL trichloroacetic acid and 0.25 mL ferric chloride were added to the samples. The prepared samples were read in a spectrophotometer (Shimadzu, Kyoto, Japan) at 700 nm wavelength. The obtained absorbance values were calculated as Trolox equivalent mmol TE kg−1 dry weight [27].

2.8. Fatty Acid Composition

The fatty acid composition of the oils obtained from hazelnut kernels was analyzed using gas chromatography (GC) according to the method reported by Altun et al. [28]. To achieve this, 0.1 g of hazelnut oil was weighed into a test tube, to which 1 mL of potassium methylate and 4 mL of hexane were then added. The mixture was shaken for 30 s, after which 0.5 mL of 25% sulfuric acid (H2SO4) was added. The resulting solution was diluted with hexane and passed through a 0.45 μm membrane filter [29]. The derivatized samples were then injected into a GC instrument (Shimadzu, Kyoto, Japan) equipped with a flame ionization detector (FID). Analysis was performed using a capillary column (TR-CN100, Teknokroma, Barcelona, Spain) measuring 0.25 mm × 0.20 µm and 100 m in length. The column temperature was initially set to 140 °C for 5 min, then increased to 240 °C at a rate of 4 °C/min, and held at this temperature for a further 15 min. The injector and detector temperatures were set to 250 °C, and the flow rate of nitrogen, which was used as the carrier gas, was set to 3 mL/min depending on the method. The injection volume was 1 µL and the split ratio was 1:100. Fatty acid methyl esters (FAMEs) were identified by comparing their retention times with those of commercial standards, and the results were expressed as a percentage of each fatty acid’s relative peak area. The fatty acids identified were palmitic, palmitoleic, palmitoleic, stearic, oleic, linoleic, linolenic, arachidic, and 11-eicosenoic.

2.9. Statistical Analysis

Data were analyzed using JMP Pro 16 (trial) statistical software. The effect of geographical origin on cultivars was determined by LSD multiple comparison test at 5% significance level. PCA was performed according to the nut properties, bioactive contents, and fatty acid composition of the cultivars investigated based on geographic origin.

3. Results and Discussion

3.1. Nut Traits

For the Çakıldak hazelnut cultivar, nut weight, kernel weight, and kernel ratio were significantly influenced by geographic origins (p < 0.05), except for shell thickness. According to the geographic origins, nut weight was determined to be from 1.68 g (Giresun) to 2.31 g (Samsun), kernel weight from 0.97 g (Giresun) to 1.33 g (Samsun), kernel ratio from 53.63% (Ordu) to 57.90% (Giresun), and shell thickness from 0.87 mm (Samsun) to 0.93 mm (Ordu). Generally, the highest nut weight, kernel weight, and kernel ratio in the Çakıldak cultivar was determined to be in Samsun and the lowest in Giresun (Table 1). Bozkurt [30] recorded a nut weight of 1.80–2.00 g, kernel weight of 0.92–1.00 g, kernel ratio of 50.9–53.7%, and shell thickness of 0.96 mm for the Çakıldak hazelnut cultivar grown in the Kabataş (Ordu/Türkiye) region. For the Çakıldak hazelnut cultivar grown in different altitudes in Gülyalı (Ordu/Türkiye) ecological conditions, these parameters were determined to be from 1.52 to 2.04 g, 0.84 to 1.11 g, 54.31 to 55.52%, and 1.09 to 1.16 mm by Gülsoy et al. [31], respectively. Also, Balta et al. [17] reported a nut weight of 2.06–2.26 g, kernel weight of 1.18 to 1.27 g, kernel ratio of 55.1 to 57.4%, and shell thickness of 0.98 to 1.12 mm for the Çakıldak hazelnut cultivar grown in the Çarşamba (Samsun/Türkiye) region. The nut weight, kernel weight, and kernel ratio values were consistent with findings by other researchers. In contrast, the shell thickness was lower than the findings of other researchers.
For the Palaz hazelnut cultivar, geographic origin had a significant effect on the nut weight and kernel weight (p < 0.05). However, there was no significant difference between the geographic origins for the kernel ratio and shell thickness. By regions, nut weight was determined to be from 1.87 g (Ordu) to 2.20 g (Samsun), kernel weight from 0.96 g (Ordu) to 1.16 g (Samsun), kernel ratio from 51.24% (Ordu) to 53.05% (Giresun), and shell thickness from 1.08 mm (Ordu) to 1.17 mm (Samsun). Generally, the highest nut weight, kernel weight, and kernel ratio in the Palaz cultivar was determined to be in Samsun and the lowest in Ordu (Table 1). For the Palaz hazelnut cultivar grown in the Samsun district, 2.0–2.30 g nut weight, 1.01–1.11 g kernel weight, 50.55–51.88% kernel ratio, and 0.91–0.95 mm shell thickness were reported [32]. For the Palaz hazelnut cultivar grown in the Giresun region, 1.89 g nut weight, 1.12 g kernel weight, 54.07% kernel ratio, and 0.96 mm shell thickness were recorded [33]. For the Palaz hazelnut cultivar grown in Ordu ecological conditions, 1.79 g nut weight, 0.98 g kernel weight, and 55.11% kernel ratio were reported [34]. The nut and kernel weights were within the range of values reported by other researchers. The kernel ratio was higher than Demir and Beyhan’s [32] findings, but lower than those of other researchers. Shell thickness was higher than that reported by the other researchers.
For the Tombul hazelnut cultivar, geographic origin had a significant effect on the nut weight, kernel weight, and kernel ratio (p < 0.05) but not shell thickness. Based on the geographic origins, nut weight was determined to be from 1.83 g (Ordu) to 2.12 g (Samsun), kernel weight from 0.98 g (Ordu) to 1.19 g (Samsun), kernel ratio from 53.50% (Ordu) to 56.22% (Samsun), and shell thickness from 0.96 mm (Samsun) to 0.99 mm (Ordu). The highest nut weight, kernel weight, and kernel ratio for the Tombul cultivar was determined to be in Samsun and the lowest in Ordu (Table 1). Balta et al. [35] reported a range of 2.05–2.32 g for nut weight, 1.17–1.28 g for kernel weight, 53.86–57.53% for kernel ratio, and 0.82–0.94 mm for shell thickness of the Tombul hazelnut cultivar grown in Samsun ecological conditions. For the Tombul hazelnut cultivar grown in the Giresun region, Turan [36] determined a range of 1.59–2.49 g for nut weight, 0.75–1.24 g for kernel weight, 45.70–54.30% for the kernel ratio, and 0.95–1.24 for mm shell thickness. Gülsoy et al. [31] reported a range of 1.82–2.04 g for nut weight, 0.96–1.06 g for kernel weight, 51.08–52.67% for the kernel ratio, and 0.94–1.12 mm for shell thickness for the Tombul hazelnut cultivar grown in different altitudes in Gülyalı (Ordu/Türkiye) region. The nut weight and kernel weight values were lower than those reported by Balta et al. [35] but were consistent with the findings of other researchers. Similar results were recorded for shell thickness. However, the kernel ratio was higher than that reported by Turan [36] and Gülsoy et al. [31].
It was reported that geographic origin had a significant effect on the nut weight, kernel weight, and shell thickness of the Mincane hazelnut variety, while the kernel ratio was unaffected by geographic differences [22]. Another study reported that nut and kernel weight were affected by geographical origin for the Kalınkara variety, but the kernel ratio and shell thickness were not [37]. The effect of location on the nut weight, kernel weight, kernel ratio, and shell thickness of Barcelona and Tonda di Giffoni cultivars was reported to be insignificant [5]. In the present study, the effect of geographic origin on the shell thickness of the Çakıldak and Tombul cultivars was not significant, whereas it was significant for other traits. For the Palaz variety, regional differences affected nut and kernel weight but not the kernel ratio and shell thickness. In general, it is understood that geographical differences affect these traits in hazelnut varieties. In addition, many researchers have reported that factors such as cultivar, cultural practices, climatic factors (especially drought), crop load, and altitude affect these traits [23,38,39]. In fact, the lowest kernel ratio was recorded in the hazelnut cultivars grown in the Ordu region. Fruit development in hazelnut occurs between May and August. When the precipitation data were analyzed, lower precipitation was recorded in the Ordu region compared to other regions in June and July. Consequently, the kernel ratio was lower for the cultivars grown in the Ordu region than for those grown in other regions.
The effect of geographic origin on nut and kernel dimension (length, width, and thickness) of the Çakıldak hazelnut cultivar was significant (p < 0.05). By regions, the largest nut dimensions (nut length, width, and thickness) for the Çakıldak cultivar were measured in Ordu and the smallest in Giresun. The Çakıldak cultivar grown in Samsun had the largest kernel dimensions (kernel length, width, and thickness), while the Çakıldak cultivar grown in Giresun had the smallest. The largest nut size was determined to be the Çakıldak cultivar grown in Ordu (18.00 mm) and the smallest to be the Çakıldak cultivar grown in Giresun (16.36 mm). The Çakıldak cultivar grown in Samsun (14.23 mm) had the largest kernel size, while the Çakıldak cultivar grown in Giresun (12.66 mm) had the smallest (Table 2). For the Çakıldak hazelnut cultivar grown in the Samsun region, Beyhan and Demir [40] recorded a nut size of 16.66–17.52 mm and kernel size of 11.66–13.07 mm. For the Çakıldak hazelnut cultivar grown in Ordu ecological conditions, nut size was determined to be 16.11 mm by Bostan and Günay [34]. For the Çakıldak hazelnut cultivar grown in different altitudes in the same ecology, Gülsoy et al. [31] reported a nut size of 16.75–17.24 mm and kernel size of 12.77–13.90 mm. Nut and kernel size values were consistent with the findings of the researchers.
For the Palaz hazelnut cultivar, significant differences were found in the nut and kernel dimensions in the different geographic origins (p < 0.05), except for kernel length and kernel width. The highest nut dimensions in the Palaz cultivar were found in Samsun, and the lowest was determined to be in Giresun. Generally, the largest kernel dimensions for the Palaz cultivar were measured in Samsun. The lowest kernel dimensions for the Palaz cultivar were determined to be in Ordu. Samsun (17.97 mm) had the largest nut size, while Giresun (16.99 mm) had the smallest. The largest kernel size in the Palaz cultivar was determined to be in Samsun (13.64 mm), and the smallest to be in Ordu (12.93 mm) (Table 2). For the Palaz hazelnut cultivar grown in the Samsun district, 17.07–17.63 mm nut size and 13.33–14.57 mm kernel size were reported [40]. For the Palaz hazelnut cultivar grown in the Ordu region, a 16.06 mm nut size was recorded [34]. For the Palaz hazelnut cultivar grown in different altitudes in the same ecological conditions, 16.78–16.96 mm nut size and 13.61–13.67 mm kernel size were reported [31]. The nut size value was consistent with the findings of Beyhan and Demir [40], but higher than those of other researchers. Conversely, kernel size was higher than the results of Gülsoy et al. [31] but lower than findings of Beyhan and Demir [40].
For the Tombul hazelnut cultivar, geographic origin had a significant effect on the kernel length and thickness (p < 0.05), but no significant effect was found for other nut and kernel dimensional traits. Generally, the largest nut dimensions in the Tombul cultivar were measured in Samsun and the smallest in Giresun. Samsun had the largest kernel dimensions. The Tombul cultivar grown in Ordu had the smallest kernel dimensions except for kernel length. The largest nut size in the Tombul cultivar was determined to be in Samsun (17.21 mm) and the smallest to be in Giresun (16.50 mm). The Tombul cultivar grown in Samsun (13.65 mm) had the largest kernel size, while the Tombul cultivar grown in Giresun (12.85 mm) had the smallest (Table 2). Beyhan and Demir [40] reported a range of 16.84–17.80 mm for nut size and 13.28–14.48 mm for kernel size for the Tombul hazelnut cultivar grown in Samsun ecological conditions. For the Tombul hazelnut cultivar grown in the Giresun region, Turan [36] determined a range of 16.60–18.82 mm for nut size and 12.12–13.98 mm for kernel size. Gülsoy et al. [31] reported a range of 16.45–16.59 mm for nut size and 13.02–13.29 mm for kernel size for the Tombul hazelnut cultivar grown in different altitudes in the Gülyalı (Ordu/Türkiye) region. The nut size value was higher than that reported by Gülsoy et al. [31] and consistent with findings from other studies. The kernel size was lower than Beyhan and Demir’s [40] findings and similar to those of other researchers.
While geographical origin had no significant effect on the nut size of Kalınkara, it did have a significant effect on the kernel size. While the geographical origin had no significant effect on the size of Kalınkara nuts, it did have a significant effect on the size of the kernels [37]. Similar results were reported for the Mincane cultivar [22]. In addition, it was reported that nut and kernel dimensions did not vary according to geographic origin in the Barcelona and Tonda di Giffoni cultivars [5]. In the present study, however, the effect of geographic origin on nut and kernel sizes was significant in all varieties. It has been reported that the nut and kernel sizes of hazelnut are affected by genetic structure [10], and that these traits change depending on ecological conditions [31]. In particular, nut and kernel size decreases under arid conditions. In addition, it was reported that cultivation conditions had a significant effect on these traits. Inadequate technical and cultural practices were found to have a negative impact on nut and kernel size [17].

3.2. Bioactive Compounds

For the Çakıldak hazelnut cultivar, total phenolics and total flavonoids were significantly influenced by geographic origins (p < 0.05). The highest total phenolics was found in the Çakıldak variety grown in Samsun (27.92 mg g−1), and the lowest in the Çakıldak variety grown in Giresun (23.05 mg g−1). The highest content of total flavonoids was determined to be between 83.2 mg kg−1 (Giresun) and 75.3 mg kg−1 (Ordu) (Table 3). For the Çakıldak hazelnut cultivar, total phenolics and total flavonoids ranged from 3.33 mg g−1 to 105 mg kg−1 in the Giresun region [9] and 9.10–13.09 mg g−1 to 86.2–131.7 mg kg−1 in the Samsun region [17], respectively. While the total phenolic values were higher than those reported by the researchers, the total flavonoid values were low.
For the Çakıldak hazelnut cultivar, significant differences were determined for the antioxidant activity in the different geographic origins (p < 0.05). According to DPPH and FRAP assays, the highest antioxidant activity in the Çakıldak cultivar was found in Giresun (37.08 and 46.35 mmol kg−1, respectively). The lowest antioxidant activity in the Çakıldak cultivar was determined to be in Ordu (34.41 and 15.95 mmol kg−1, respectively) (Table 3). For the Çakıldak hazelnut cultivar, antioxidant activity was recorded a range of 29.0 mmol kg−1 based on DPPH assay in the Giresun district [9], 25.54–37.37 mmol kg−1 based on DPPH assay, and 39.05–70.27 mmol kg−1 based on FRAP assay in the Samsun region [17]. The antioxidant activity, as determined by the DPPH test, was higher than that reported by Yaman et al. [9] but similar to that reported by Balta et al. [17]. However, the antioxidant activity according to the FRAP test was lower than that reported by Balta et al. [17].
For the Palaz hazelnut cultivar, geographic origin had a significant effect on total phenolics and total flavonoids (p < 0.05). For total phenolics, the highest content in the Palaz cultivar was determined to be in Giresun (13.24 mg g−1) and the lowest to be in Samsun (7.68 mg g−1). The highest total flavonoids in the Palaz cultivar was found in Samsun (57.2 mg kg−1) and the lowest in the Giresun (51.7 mg kg−1) (Table 3). Karakaya [41] reported a range of 8.71–19.34 mg g−1 for total phenolics and 56–178 mg kg−1 for total flavonoids of the Palaz hazelnut cultivar grown in the Ordu region. In Giresun ecological conditions, Yaman et al. [9] determined that Palaz kernels contain 4.40 mg g−1 total phenolics and 125 mg kg−1 total flavonoids. Yılmaz et al. [42] reported a range of 4.65–9.15 mg g−1 for total phenolics and 44.5–75.6 mg kg−1 for total flavonoids based on orchards of the Palaz hazelnut cultivar grown in the Çarşamba (Samsun) region. The total phenolic value was lower than that reported by Karakaya [41] but higher than that recorded by other researchers. Total flavonoid values were lower than those reported by other researchers.
The effect of geographic origin on the antioxidant activity of the Palaz hazelnut cultivar was significant (p < 0.05). In the DPPH assay, the highest antioxidant activity in the Palaz cultivar was determined to be in Ordu (8.96 mmol kg−1) and the lowest to be in Samsun (2.93 mmol kg−1). Similar results were found in the FRAP assay. According to the result of this assay, the highest antioxidant activity in the Palaz cultivar was determined to be in Ordu (12.79 mmol kg−1) and the lowest to be in the Samsun (4.27 mmol kg−1) (Table 3). For the Palaz hazelnut cultivar, Karakaya [41] reported 16.4–19.0 mmol kg−1 AA based on DPPH assay and 9.9–28.6 mmol kg−1 AA based on FRAP assay in the Ordu region. Yaman et al. [9] determined 0.37 mmol kg−1 AA according to DPPH assay in the Giresun region. Yılmaz et al. [42] recorded 3.54–15.50 mmol kg−1 AA based on DPPH assay and 9.17–23.58 mmol kg−1 AA based on FRAP assay in the Çarşamba (Samsun) region. According to DPPH test, antioxidant activity was higher than the results reported by Yaman et al. [9] but lower than the findings of other researchers. Similar results were recorded in the FRAP test.
For the Tombul hazelnut cultivar, total phenolics and total flavonoids were significantly influenced by the geographic origins (p < 0.05). The highest total phenolics in the Tombul cultivar was found in Samsun (20.83 mg g−1) and the lowest in Ordu (5.50 mg g−1). The highest content of total flavonoids in the Tombul cultivar was determined to be in Samsun (85.7 mg kg−1) and the lowest to be in the Giresun (49.8 mg kg−1) (Table 3). For the Tombul hazelnut cultivar, total phenolics and total flavonoids ranged from 4.35 to 6.26 mg g−1 and 39 to 58 mg kg−1 in the Ordu region [41], 4.87 mg g−1 and 137 mg kg−1 in the Giresun region [9], and 5.51–15.92 mg g−1 and 48.6–233.0 mg kg−1 in the Çarşamba (Samsun) region [42], respectively. The total phenolic value was higher than the results reported by Karakaya [41] and Yaman et al. [9] but similar to the results recorded by Yılmaz et al. [42]. Conversely, the total flavonoid value was higher than reported by Karakaya [41] but lower than documented by other researchers.
For the Tombul hazelnut cultivar, significant differences were determined for the antioxidant activity in the different geographic origins (p < 0.05). According to DPPH and FRAP assays, the highest antioxidant activity in the Tombul cultivar was found in Samsun (26.62 and 18.22 mmol kg−1, respectively). In comparison to the Tombul cultivar grown in Samsun, the Tombul cultivar grown in Ordu exhibited the lowest antioxidant activity (3.46 and 5.86 mmol kg−1, respectively) (Table 3). For the Tombul hazelnut cultivar, antioxidant activity was recorded in a range of 13.5–15.1 mmol kg−1 based on DPPH assay and 3.5–6.7 mmol kg−1 based on FRAP assay in the Ordu region [41], 4.2 mmol kg−1 based on DPPH assay in the Giresun district [9], and 10.33–36.98 mmol kg−1 based on DPPH assay and 4.74–28.62 mmol kg−1 based on FRAP assay in the Samsun region [42]. According to DPPH test, antioxidant activity was higher than the results reported by Karakaya [41] and Yaman et al. [9] but similar to those recorded by Yılmaz et al. [42]. Similar results were recorded in the FRAP test.
Related studies have reported a significant effect of geographic differences on the total phenolic and flavonoid content, as well as the antioxidant activity, in Kalınkara and Mincane hazelnut cultivars [22,37]. Similar results were observed in the Barcelona and Tonda di Giffoni cultivars [5]. In addition, these traits were reported to vary according to geographic origin for almond and walnut cultivars [20,43]. Similar results were recorded in the present study. Generally, the fact that the cultivars exhibited different traits in different locations indicates that geographical origin affects bioactive compounds. Previous studies have revealed that variations in environmental factors, such as temperature, light exposure, and UV radiation, can affect the total phenolic and flavonoid content, as well as the antioxidant activity, in hazelnuts [15,16]. In addition, Yaman et al. [9] reported that these properties varied significantly depending on the hazelnut cultivar. Tonkaz et al. [44] stated that cultural practices affect the bioactive content of hazelnuts, with non-irrigated plants having higher phenolic and antioxidant activity. It was also reported that these contents decreased as the fruit ripened [45].

3.3. Fatty Acid Composition

The fatty acid composition of hazelnut oil is an important parameter for assessing its economic and nutritional value. Hazelnuts grown in different geographic origins may have the same fatty acid content but significant variations in their content [4]. Oleic acid is the main fatty acid found in hazelnuts, accounting for around 80% of hazelnut oil. It is followed by linoleic, palmitic, and stearic acids [10,46].
The effect of geographic origin on the fatty acid composition of the Çakıldak hazelnut cultivar was significant (p < 0.05), except for oleic acid. Based on the geographic origins, palmitic acid was determined to be from 6.14% (Ordu) to 8.03% (Giresun), palmitoleic acid from 0.0% (Giresun) to 0.54% (Samsun), stearic acid from 1.75% (Giresun) to 2.24% (Ordu), oleic acid from 82.62% (Samsun) to 84.28% (Giresun), and linoleic acid from 5.95% (Giresun) to 7.70% (Ordu). Linolenic acid, arachidic acid, and 11-eicosenoic acid were determined to be 0.00% (Table 4). Çetin et al. [12] reported a range of 5.07% for palmitic acid, 0.12% for palmitoleic acid, 3.02% for stearic acid, 85.08% for oleic acid, 6.16% for linoleic acid, 0.15% for arachidic acid, and 0.22% for 11-eicosenoic acid for the Çakıldak hazelnut cultivar grown in Samsun ecological conditions. In the Giresun region, Yaman et al. [9] determined that Çakıldak kernel oil contains 6.09% palmitic acid, 0.05% palmitoleic acid, 2.41% stearic acid, 77.10% oleic acid, 13.33% linoleic acid, and 0.96% linolenic acid. Balta et al. [17] reported a range of 6.45–6.76% for palmitic acid, 0.21–0.28% for palmitoleic acid, 2.26–2.49% for stearic acid, 82.98–83.61% for oleic acid, 6.71–7.64% for linoleic acid, 0.13–0.14% for arachidic acid, and 0.10–0.16% for 11-eicosenoic acid depending on the plant density of the Çakıldak hazelnut cultivar grown in the Çarşamba (Samsun) region. The fatty acid composition of the Çakıldak hazelnut cultivar was consistent with the findings of the researchers, except for palmitic and palmitoleic acids.
For the Palaz hazelnut cultivar, significant differences were determined for the fatty acid composition in the different geographic origins (p < 0.05). By region, palmitic acid was determined to be from 4.86% (Ordu) to 7.91% (Giresun), palmitoleic acid from 0.0% (Giresun) to 0.24% (Samsun), stearic acid from 1.77% (Ordu) to 2.61% (Samsun), oleic acid from 78.90% (Ordu) to 84.56% (Samsun), linoleic acid from 5.83% (Samsun) to 14.06% (Ordu), linolenic acid from 0.0% (Giresun and Samsun) to 0.09% (Ordu), arachidic acid from 0.0% (Giresun and Ordu) to 0.11% (Samsun), and 11-eicosenoic acid from 0.0% (Giresun) to 0.14% (Ordu) (Table 4). For the Palaz hazelnut cultivar grown in the Giresun district, 5.51% palmitic acid, 0.05% palmitoleic acid, 2.85% stearic acid, 70.47% oleic acid, 19.19% linoleic acid, 1.86% linolenic acid, and 0.03% arachidic acid were reported [9]. For the Palaz hazelnut cultivar grown in the Ordu region, 4.58–6.79% palmitic acid, 0.09–0.17% palmitoleic acid, 1.99–2.08% stearic acid, 80.37–83.55% oleic acid, 9.44–10.61% linoleic acid, 0.02–0.07% arachidic acid, and 0.07–0.15% 11-eicosenoic acid were reported [41]. For the Palaz hazelnut cultivar grown in Samsun ecological conditions, 6.84–7.09% palmitic acid, 0.23–0.31% palmitoleic acid, 2.53–2.68% stearic acid, 82.05–83.15% oleic acid, 6.66–7.89% linoleic acid, 0.08–0.09% linolenic acid, 0.13–0.21% arachidic acid, and 0.13–0.22% 11-eicosenoic acid were reported [42]. The fatty acid composition of the Palaz hazelnut cultivar ranged within the values reported by other researchers.
For the Tombul hazelnut cultivar, fatty acid composition was significantly influenced by the geographic origin (p < 0.05), except for stearic acid. Based on the geographic origins, palmitic acid was determined to be from 5.51% (Giresun) to 8.05% (Samsun), palmitoleic acid from 0.0% (Giresun) to 0.25% (Samsun), stearic acid from 2.27% (Ordu) to 2.48% (Giresun), oleic acid from 80.40% (Samsun) to 84.73% (Giresun), and linoleic acid from 7.28% (Giresun) to 10.60% (Ordu). Linolenic acid, arachidic acid, and 11-eicosenoic acid were not detected (Table 4). Çetin et al. [12] reported a range of 5.72% for palmitic acid, 0.16% for palmitoleic acid, 2.60% for stearic acid, 82.97% for oleic acid, 8.02% for linoleic acid, 0.14% for arachidic acid, and 0.22% for 11-eicosenoic acid for the Tombul hazelnut cultivar grown in Samsun ecological conditions. In the Giresun region, Yaman et al. [9] determined that Tombul kernel oil contains 5.73% palmitic acid, 0.05% palmitoleic acid, 2.17% stearic acid, 71.18% oleic acid, 19.03% linoleic acid, 1.75% linolenic acid, and 0.04% arachidic acid. Karakaya [41] reported a range of 5.75–6.11% for palmitic acid, 0.07% for palmitoleic acid, 2.29–2.60% for stearic acid, 80.17–82.45% for oleic acid, and 9.13–11.42% for linoleic acid depending on the cluster drop density of the Tombul hazelnut cultivar grown in the Ordu region. The fatty acid composition of the Tombul hazelnut cultivar was consistent with the findings of other researchers, except for palmitic and palmitoleic acids.
It has been reported that geographic origin and harvest year had a significant effect on hazelnut fatty acid composition [47]. In addition, many researchers have reported that cultivar, cultural practices, nut maturity, soil type, and crop load affect hazelnut fatty acid composition [17,48,49]. Indeed, Bacchetta et al. [4] stated that the fatty acid composition of seven hazelnut cultivars varied depending on location, and that geographic origin plays an important role in the fatty acid composition of hazelnuts. Furthermore, geographical differences were reported to cause variations in the fatty acid composition of almonds and walnuts [19,20,50]. In the present study, the fatty acid composition of the investigated cultivars varied according to geographical origin. Our findings confirmed that both cultivar and geographical origin play an important role in determining the fatty acid profiles of hazelnut cultivars, with geographical origin having a more significant effect.

3.4. Principal Component Analysis (PCA)

For the Çakıldak hazelnut cultivar, 21 traits were used for PCA. The first two components explained 100% of total variation in the data. The Samsun region, located in the first region of the PCA plane, was related to nut weight, kernel weight, kernel length, kernel width, kernel thickness, kernel size, total phenolics, linoleic acid, and palmitoleic acid. The Giresun region, located in the second region, was associated with the kernel ratio, (according to FRAP and DPPH assays), oleic acid, palmitoleic acid, and total flavonoids. The Ordu region was related to nut length, nut width, nut thickness, nut size, shell thickness, linoleic acid, and stearic acid, and was located in the third region (Figure 4). Generally, the Çakıldak hazelnut cultivar produced better results in terms of nut traits and total phenolics in Samsun and in terms of antioxidant activity and fatty acids in Giresun.
Out of the 24 components, the first 2 components explained 100% of total variation in the data. The Samsun region, located in the first region of the PCA plane, was related to the nut weight, kernel weight, shell thickness, nut length, nut width, nut thickness, nut size, kernel length, kernel thickness, kernel size, total flavonoids, arachidic acid, oleic acid, palmitoleic acid, and stearic acid. The Ordu region was associated with antioxidant activity (according to FRAP and DPPH assays), linoleic acid, linolenic acid, and 11-eicosenoic acid, and was located in the second region. The Giresun region, located in the third region, was related to the kernel ratio, kernel width, total phenolics, and palmitic acid (Figure 5). In general, the Palaz hazelnut variety recorded better results in Samsun in terms of nut properties and fatty acids, in Ordu in terms of antioxidant activity, and in Giresun in terms of total phenolic content.
PCA was performed on the 20 traits of the Tombul hazelnut cultivar, and the first two components explained 100% of the total variation in the data. The Samsun region, located in the first region of the PCA plane, was related to the nut weight, kernel weight, kernel ratio, nut length, nut width, nut thickness, nut size, kernel length, kernel width, kernel thickness, kernel size, total phenolics, total flavonoids, antioxidant activity (according to FRAP and DPPH assays), palmitic acid, and palmitoleic acid. The Ordu region was associated with shell thickness and linoleic acid and was located in the second region. The Giresun region, located in the third region, was related to oleic and stearic acids (Figure 6). Generally, the Tombul hazelnut cultivar produced better results in terms of nut traits, total phenolics, and antioxidant activity in Samsun and in terms of fatty acids in Giresun.

4. Conclusions

This study highlights the significant impact of geographical origin on the nut characteristics, bioactive content, and fatty acid composition of major Turkish hazelnut cultivars. Geographical differences were found to significantly affect these traits in the examined cultivars. The highest nut and kernel weights and sizes were recorded in the hazelnut cultivars grown in Samsun. Overall, the highest levels of phenolic and flavonoid compounds were found in the hazelnut cultivars grown in Samsun. These results suggest that this region is particularly ideal for producing hazelnuts that are higher in nutritional and functional value and of better quality. The antioxidant activity of the cultivars differed according to geographical origin. The highest oleic acid was found in the hazelnut cultivars grown in Giresun and the highest linoleic acid in the hazelnut cultivars grown in Ordu. The data obtained show that the Giresun ecological conditions, in particular, have crucial potential to enhance the fatty acid profile of hazelnut cultivars. These results emphasize the critical role of geographical origin in determining the nutritional and commercial value of hazelnuts and support the strategy of selecting cultivars that are appropriate for the respective region. Future studies should investigate the molecular mechanisms underlying the variations in nut traits, bioactive compounds, and fatty acid composition in hazelnuts based on geographical origin.

Author Contributions

Conceptualization, H.K. and O.K.; methodology, H.K. and O.K.; software, O.K.; validation, H.K. and O.K.; formal analysis, H.K. and O.K.; investigation, H.K. and O.K.; resources, H.K. and O.K.; data curation, H.K. and O.K.; writing—original draft preparation, H.K.; writing—review and editing, O.K.; visualization, O.K.; supervision, H.K. and O.K.; project administration, H.K. and O.K.; funding acquisition, H.K. and O.K. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Data Availability Statement

Data is contained within the article.

Conflicts of Interest

The authors declare no conflicts of interest.

Abbreviations

The following abbreviations are used in this manuscript:
cvs.Cultivars
LSDLeast Significant Difference
RHRelative Humidity

References

  1. Food and Agriculture Organization Statistics (FAO). Hazelnut Production Statistics. 2025. Available online: https://www.fao.org/faostat/en/#data/QCL (accessed on 11 June 2025).
  2. Karadeniz, T.; Bostan, S.Z.; Tuncer, C.; Tarakçıoğlu, C. Fındık Yetiştiriciliği; Ordu Ziraat Odası Başkanlığı Bilimsel Yayınlar Serisi: Ordu, Türkiye, 2009; pp. 1–154. [Google Scholar]
  3. İslam, A. Hazelnut culture in Turkey. Akad. Zir. Der. 2018, 7, 259–266. [Google Scholar]
  4. Bacchetta, L.; Aramini, M.; Procacci, S.; Zinni, A.; Di Giammatteo, V.; Battarelli, M.R.; Spera, D. Influence of genotype and geographical origin on lipid fraction of hazelnuts (Corylus avellana) in Europe. Acta Hortic. 2018, 1226, 333–338. [Google Scholar] [CrossRef]
  5. Gavilán-CuiCui, G.; Padilla-Contreras, D.; Manterola-Barroso, C.; Morina, F.; Meriño-Gergichevich, C. Antioxidant performance in hazelnut (Corylus avellana L.) cultivars shell is substantially influenced by season and locality. Agronomy 2024, 14, 1412. [Google Scholar] [CrossRef]
  6. Silvestri, C.; Bacchetta, L.; Bellincontro, A.; Cristofori, V. Advances in cultivar choice, hazelnut orchard management, and nut storage to enhance product quality and safety: An overview. J. Sci. Food Agric. 2021, 101, 27–43. [Google Scholar] [CrossRef] [PubMed]
  7. Özdemir, F.; Akıncı, I. Physical and nutritional properties of four major commercial Turkish hazelnut varieties. J. Food Eng. 2004, 63, 341–347. [Google Scholar] [CrossRef]
  8. Król, K.; Gantner, M. Morphological traits and chemical composition of hazelnut from different geographical origins: A review. Agriculture 2020, 10, 375. [Google Scholar] [CrossRef]
  9. Yaman, M.; Balta, M.F.; Karakaya, O.; Kaya, T.; Necas, T.; Yildiz, E.; Dirim, E. Assessment of fatty acid composition, bioactive compounds, and mineral composition in hazelnut genetic resources: Implication. Horticulturae 2023, 9, 1008. [Google Scholar] [CrossRef]
  10. Cristofori, V.; Ferramondo, S.; Bertazza, G.; Bignami, C. Nut and kernel traits and chemical composition of hazelnut (Corylus avellana L.) cultivars. J. Sci. Food Agric. 2008, 88, 1091–1098. [Google Scholar] [CrossRef]
  11. Bacchetta, L.; Aramini, M.; Zini, A.; Di Giammatteo, V.; Spera, D.; Drogoudi, P.; Botta, R. Fatty acids and alpha-tocopherol composition in hazelnut (Corylus avellana L.): A chemometric approach to emphasize the quality of European germplasm. Euphytica 2013, 191, 57–73. [Google Scholar] [CrossRef]
  12. Çetin, N.; Yaman, M.; Karaman, K.; Demir, B. Determination of some physicomechanical and biochemical parameters of hazelnut (Corylus avellana L.) cultivars. Turk. J. Agric. For. 2020, 44, 439–450. [Google Scholar] [CrossRef]
  13. Di Nunzio, M. Hazelnuts as source of bioactive compounds and health value underestimated food. Curr. Res. Nutr. Food Sci. J. 2019, 7, 17–28. [Google Scholar] [CrossRef]
  14. Pelvan, E.; Alasalvar, C.; Uzman, S. Effects of roasting on the antioxidant status and phenolic profiles of commercial Turkish hazelnut varieties (Corylus avellana L.). J. Agric. Food Chem. 2012, 60, 1218–1223. [Google Scholar] [CrossRef]
  15. Gülsoy, E.; Kaya, E.D.; Türkhan, A.; Bulut, M.; Koyuncu, M.; Güler, E.; Muradoğlu, F. The effect of altitude on phenolic, antioxidant and fatty acid compositions of some Turkish hazelnut (Corylus avellana L.) cultivars. Molecules 2023, 28, 5067. [Google Scholar] [CrossRef]
  16. Khavari, M.; Fatahi, R.; Zamani, Z. Salicylic acid and kaolin effects on pomological, physiological, and phytochemical characters of hazelnut (Corylus avellana) at warm summer condition. Sci. Rep. 2021, 11, 4568. [Google Scholar] [CrossRef]
  17. Balta, F.; Yılmaz, M.; Karakaya, O.; Çalışkan, K.; Yarılgaç, T.; Bostan, S.Z.; Uzun, S. Effect of Plant Density on Nut Traits, Nut Yield, Cluster Distribution and Chemical Components in Çakıldak (Corylus avellana L.) Hazelnut Cultivar. Appl. Fruit Sci. 2024, 66, 2295–2305. [Google Scholar] [CrossRef]
  18. Varol, D.; Bostan, S. Bioactive Components and Aflatoxins Changing According to the Farming Systems in Hazelnut. Appl. Fruit Sci. 2025, 67, 97. [Google Scholar] [CrossRef]
  19. Kodad, O.; Estopañán, G.; Juan, T.; Socias i Company, R. Protein content and oil composition of almond from Moroccan seedlings: Genetic diversity, oil quality and geographical origin. J. Am. Oil Chem. Soc. 2013, 90, 243–252. [Google Scholar] [CrossRef]
  20. Ma, X.; Wang, W.; Zheng, C.; Liu, C.; Huang, Y.; Zhao, W.; Du, J. Quality evaluation of walnuts from different regions in China. Foods 2023, 12, 4123. [Google Scholar] [CrossRef]
  21. Matin, A.; Brandić, I.; Gubor, M.; Pezo, L.; Krička, T.; Matin, B.; Antonović, A. Effect of conduction drying on nutrient and fatty acid profiles: A comparative analysis of hazelnuts and walnuts. Front. Sustain. Food Syst. 2024, 8, 1351309. [Google Scholar] [CrossRef]
  22. Karakaya, O. The Effect of region on nut and biochemical traits of Mincane hazelnut cultivar. Black Sea J. Agric. 2023, 6, 134–139. [Google Scholar] [CrossRef]
  23. Ay, A.; Kızılkaya, R. Ordu ve Giresun illerindeki fındık bahçelerinin toprak özellikleri ile biyolojik özellikleri arasındaki ilişkiler. Top. Bil. Bit. Bes. Derg. 2021, 9, 71–78. [Google Scholar] [CrossRef]
  24. Güler, E.; Balta, F. Determination of yield and quality characteristics of hazelnut populations of Taskesti district (Mudurnu-Bolu). Int. J. Agric. Wildl. Sci. 2020, 6, 115–128. [Google Scholar]
  25. Firestone, D. (Ed.) Physical and Chemical Characteristics of Oils, Fats and Waxes; AOCS Press: Champaign, IL, USA, 1997. [Google Scholar]
  26. Blois, M.S. Antioxidant determinations by the use of a stable free radical. Nature 1958, 181, 1199–1200. [Google Scholar] [CrossRef]
  27. Benzie, I.F.F.; Strain, J.J. The ferric reducing ability of plasma (FRAP) as a measure of “antioxidant power”: The FRAP assay. Anal. Biochem. 1996, 239, 70–76. [Google Scholar] [CrossRef]
  28. Altun, M.; Çelik, S.E.; Güçlü, K.; Özyürek, M.; Erçağ, E.; Apak, R. Total antioxidant capacity and phenolic contents of Turkish hazelnut (Corylus avellana L.) kernels and oils. J. Food Biochem. 2013, 37, 53–61. [Google Scholar] [CrossRef]
  29. Deutsche Gesellschaft für Fettwissenschaften (DGF). German Standard Methods for the Analysis of Fats and Other Lipids; Wissenschaftliche Verlagsgesellschaft: Stuttgart, Germany, 1998. [Google Scholar]
  30. Bozkurt, E. Çakıldak Fındık Çeşidinde Rakım, yıl ve Bahçelere Göre Verimin Değişimi Üzerine Araştırmalar. Master’s Thesis, Ordu University, Ordu, Türkiye, 2010. [Google Scholar]
  31. Gülsoy, E.; Şimşek, M.; Çevik, C. Ordu ilinin farklı rakım ve lokasyonlarında yetiştirilen bazı fındık çeşitlerinin meyve kalite özelliklerinin belirlenmesi. Int. J. Agric. Wildl. Sci. 2019, 5, 25–30. [Google Scholar]
  32. Demir, T.; Beyhan, N. Samsun ilinde yetiştirilen fındıkların seleksiyonu üzerine bir araştırma. Turk. J. Agric. For. 2000, 24, 173–183. [Google Scholar]
  33. Yılmaz, M. Bazı Fındık Çeşit ve Genotiplerinin Pomolojik, Morfolojik ve Moleküler Karakterizasyonu. Ph.D. Thesis, Çukurova University, Adana, Türkiye, 2009. [Google Scholar]
  34. Bostan, S.Z.; Günay, K. Variation of important quality characteristics in hazelnut at different years and correlations between husk number and nut and kernel traits. Acta Hortic. 2009, 845, 641–646. [Google Scholar] [CrossRef]
  35. Balta, F.; Balta, M.F.; Karadeniz, T. The evaluations on preselection of the hazelnut ‘Tombul’ and ‘Palaz’ cultivars grown in Carsamba and Terme (Samsun) districts. Acta Hortic. 1997, 445, 109–118. [Google Scholar] [CrossRef]
  36. Turan, A. Giresun Ili Bulancak Ilçesi Tombul Fındık Klon Seleksiyonu. Master’s Thesis, Ondokuz Mayıs University, Samsun, Türkiye, 2007. [Google Scholar]
  37. Karakaya, O. Nut traits and bioactive contents of Kalınkara hazelnut cultivar grown in different region. In Proceedings of the 7th International Conference on Agriculture, Animal Sciences and Rural Development, Mus, Turkey, 18–19 September 2022; pp. 18–19. [Google Scholar]
  38. Serdar, Ü.; Demir, T. Yield, cluster drop and nut traits of three Turkish hazelnut cultivars. Hortic. Sci. 2005, 32, 96–99. [Google Scholar] [CrossRef]
  39. Külahcılar, A.; Tonkaz, T.; Bostan, S.Z. Effect of irrigation regimes by mini sprinkler on yield and pomological traits in ‘Tombul’ hazelnut. Acta Hortic. 2018, 1226, 301–308. [Google Scholar] [CrossRef]
  40. Beyhan, N.; Demir, T. Performance of the local and standard hazelnut cultivars grown in Samsun province, Turkey. Acta Hortic. 2001, 556, 227–234. [Google Scholar] [CrossRef]
  41. Karakaya, O. The intensity of the cluster drop affects the bioactive compounds and fatty acid composition in hazelnuts. Grasas Aceites 2023, 74, e487. [Google Scholar] [CrossRef]
  42. Yılmaz, M.; Kaya, T.; Karakaya, O.; Balta, F.; Çalışkan, K. Orchard-based variations in oil content, fatty acid composition, and bioactive compounds in ‘Tombul’ and ‘Palaz’ hazelnut (Corylus avellana L.) cultivars. Appl. Fruit Sci. 2024, 66, 599–608. [Google Scholar] [CrossRef]
  43. Zhu, Y.; Wilkinson, K.L.; Wirthensohn, M.G. Lipophilic antioxidant content of almonds (Prunus dulcis): A regional and varietal study. J. Food Compos. Anal. 2015, 39, 120–127. [Google Scholar] [CrossRef]
  44. Tonkaz, T.; Şahin, S.; Bostan, S.Z.; Korkmaz, K. Effect of supplementary irrigation on total antioxidant capacity and phenolic content of hazelnut. Akad. Zir. Derg. 2019, 8, 79–84. [Google Scholar] [CrossRef]
  45. Cristofori, V.; Bertazza, G.; Bignami, C. Changes in kernel chemical composition during nut development of three Italian hazelnut cultivars. Fruits 2015, 70, 311–322. [Google Scholar] [CrossRef]
  46. Balta, M.F.; Yarılgaç, T.; Aşkın, M.A.; Kuçuk, M.; Balta, F.; Özrenk, K. Determination of fatty acid compositions, oil contents and some quality traits of hazelnut genetic resources grown in eastern Anatolia of Turkey. J. Food Compos. Anal. 2006, 19, 681–686. [Google Scholar] [CrossRef]
  47. Parcerisa, J.; Boatella, J.; Codony, R.; Farrà, A.; Garcia, J.; Lopez, A.; Romero, A. Influence of variety and geographical origin on the lipid fraction of hazelnuts (Corylus avellana L.) from Spain: I. Fatty acid composition. Food Chem. 1993, 48, 411–414. [Google Scholar] [CrossRef]
  48. Parcerisa, J.; Rafecas, M.; Castellote, A.I.; Codony, R.; Farran, A.; Garcia, J.; Boatella, J. Influence of variety and geographical origin on the lipid fraction of hazelnuts (Corylus avellana L.) from Spain: III. Oil stability, tocopherol content and some mineral contents (Mn, Fe, Cu). Food Chem. 1995, 53, 71–74. [Google Scholar] [CrossRef]
  49. Özdemir, M.; Açkurt, F.; Kaplan, M.; Yıldız, M.; Löker, M.; Gürcan, T.; Seyhan, F.G. Evaluation of new Turkish hybrid hazelnut (Corylus avellana L.) varieties: Fatty acid composition, α-tocopherol content, mineral composition and stability. Food Chem. 2001, 73, 411–415. [Google Scholar] [CrossRef]
  50. Zhang, X.; Fang, X.P.; Yang, X.H.; Shi, X.M.; Ren, C.M.; Meng, J.; Zhang, Y. Analysis and comparison of nutritional components of Juglans regia oil and Juglans sigillata oil from different producing areas in China. China Oils Fats 2022, 47, 60–64. [Google Scholar]
Horticulturae 11 00987 g001
Figure 1. Map of study area (blue: Giresun; green: Ordu; orange: Samsun).
Figure 1. Map of study area (blue: Giresun; green: Ordu; orange: Samsun).
Horticulturae 11 00987 g001
Horticulturae 11 00987 g002
Figure 2. Mean temperature (°C) values in study areas (means of years 2019 and 2020).
Figure 2. Mean temperature (°C) values in study areas (means of years 2019 and 2020).
Horticulturae 11 00987 g002
Horticulturae 11 00987 g003
Figure 3. Rainfall (mm) values in study areas (means of years 2019 and 2020).
Figure 3. Rainfall (mm) values in study areas (means of years 2019 and 2020).
Horticulturae 11 00987 g003
Horticulturae 11 00987 g004
Figure 4. Biplot graph based on nut traits, bioactive compounds, and fatty acid composition of Çakıldak cultivar.
Figure 4. Biplot graph based on nut traits, bioactive compounds, and fatty acid composition of Çakıldak cultivar.
Horticulturae 11 00987 g004
Horticulturae 11 00987 g005
Figure 5. Biplot graph based on nut traits, bioactive compounds, and fatty acid composition of Palaz cultivar.
Figure 5. Biplot graph based on nut traits, bioactive compounds, and fatty acid composition of Palaz cultivar.
Horticulturae 11 00987 g005
Horticulturae 11 00987 g006
Figure 6. Biplot graph based on nut traits, bioactive compounds, and fatty acid composition of Tombul cultivar.
Figure 6. Biplot graph based on nut traits, bioactive compounds, and fatty acid composition of Tombul cultivar.
Horticulturae 11 00987 g006
Table 1. Effect of geographic origins on nut weight (g), kernel weight (g), kernel ratio (%), and shell thickness (mm) of different hazelnut cultivars.
Table 1. Effect of geographic origins on nut weight (g), kernel weight (g), kernel ratio (%), and shell thickness (mm) of different hazelnut cultivars.
CultivarsGeographic OriginsNut Weight (g)Kernel Weight (g)Kernel Ratio (%)Shell Thickness (mm)
Giresun1.68 b z0.97 c57.90 a0.92 a
ÇakıldakOrdu2.13 a1.14 b53.63 b0.93 a
Samsun2.31 a1.33 a57.64 a0.87 a
Significance********ns
LSD (0.05)0.220.112.580.14
Giresun2.04 ab1.08 a53.05 a1.12 a
PalazOrdu1.87 b0.96 b51.24 a1.08 a
Samsun2.20 a1.16 a52.68 a1.17 a
Significance***nsns
LSD (0.05)0.210.122.250.22
Giresun1.84 b1.00 b54.51 ab0.97 a
TombulOrdu1.83 b0.98 b53.50 b0.99 a
Samsun2.12 a1.19 a56.22 a0.96 a
Significance****ns
LSD (0.05)0.270.112.640.16
*: p < 0.05; **: p < 0.01; ***: p < 0.001; ns: not significant. z: The differences between mean values on the same column with the same letter were not significant (p < 0.05).
Table 2. Effect of geographic origins on the nut and kernel size (mm) of different hazelnut cultivars.
Table 2. Effect of geographic origins on the nut and kernel size (mm) of different hazelnut cultivars.
CultivarsGeographic OriginsNut Length (mm)Nut Width (mm)Nut Thickness (mm)Nut Size (mm)Kernel Length (mm)Kernel Width
(mm)		Kernel Thickness (mm)Kernel Size (mm)
Giresun18.65 b z15.93 b14.74 b16.36 b14.99 b11.91 b11.37 c12.66 c
ÇakıldakOrdu20.32 a17.55 a16.35 a18.00 a16.02 a13.16 a12.15 b13.68 b
Samsun20.10 a17.37 a16.08 a17.77 a16.65 a13.48 a12.84 a14.23 a
Significance**********************
LSD (0.05)0.600.940.460.500.880.620.210.49
Giresun16.45 b18.81 ab15.86 b16.99 b12.91 a14.91 a12.59 ab13.42 ab
PalazOrdu16.57 b18.72 b15.98 b17.05 b12.22 a14.40 a12.30 b12.93 b
Samsun17.65 a19.42 a16.92 a17.97 a13.16 a14.82 a13.03 a13.64 a
Significance**********nsns**
LSD (0.05)0.490.620.290.291.410.920.540.50
Giresun18.02 a16.57 a15.06 a16.50 b14.00 b12.70 a11.94 b12.85 b
TombulOrdu18.75 a16.79 a15.32 a16.90 ab14.76 ab12.46 a11.63 b12.88 b
Samsun18.68 a17.42 a15.68 a17.21 a14.95 a13.14 a12.95 a13.65 a
Significancensnsns**ns****
LSD (0.05)1.081.090.670.550.790.690.620.43
*: p < 0.05; **: p < 0.01; ***: p < 0.001; ns: not significant. z: The differences between mean values on the same column with the same letter were not significant (p < 0.05).
Table 3. Effect of geographic origins on bioactive compounds of different hazelnut cultivars.
Table 3. Effect of geographic origins on bioactive compounds of different hazelnut cultivars.
CultivarsGeographic OriginsTotal Phenolics
(mg g−1)		Total Flavonoids (mg kg−1)DPPH
(mmol kg−1)		FRAP
(mmol kg−1)
Giresun23.05 b z83.2 a37.08 a46.35 a
ÇakıldakOrdu23.62 b75.3 b34.41 b15.95 c
Samsun27.92 a80.9 ab35.31 b23.06 b
Significance*********
LSD (0.05)1.817.81.142.78
Giresun13.24 a51.7 b8.26 a9.72 b
PalazOrdu12.34 a56.2 a8.96 a12.79 a
Samsun7.68 b57.2 a2.93 b4.27 c
Significance***********
LSD (0.05)0.913.52.471.40
Giresun13.67 b49.8 b24.32 a10.43 b
TombulOrdu5.50 c57.2 b3.46 b5.86 c
Samsun20.83 a85.7 a26.62 a18.22 a
Significance************
LSD (0.05)2.1713.22.351.99
*: p < 0.05; **: p < 0.01; ***: p < 0.001. z: The differences between mean values on the same column with the same letter were not significant (p < 0.05).
Table 4. Effect of geographic origins on fatty acid composition (%) of different hazelnut cultivars.
Table 4. Effect of geographic origins on fatty acid composition (%) of different hazelnut cultivars.
CultivarsGeographic OriginsPalmitic Acid (C16:0)Palmitoleic Acid (C16:1)Stearic Acid (C18:0)Oleic Acid (C18:1)Linoleic Acid (C18:2)Linolenic Acid (C18:3)Arachidic Acid (C20:0)11-Eicosenoic Acid (C20:1)
Giresun8.03 a z0.00 c1.75 b84.28 a5.95 b0.000.000.00
ÇakıldakOrdu6.14 c0.17 b2.24 a83.74 a7.70 a0.000.000.00
Samsun7.24 b0.54 a1.96 b82.62 a7.64 a0.000.000.00
Significance*******ns***---
LSD (0.05)0.720.060.242.840.29---
Giresun7.91 a0.00 c2.24 b83.28 a6.57 b0.00 b0.00 b0.00 c
PalazOrdu4.86 c0.17 b1.77 c78.90 b14.06 a0.09 a0.00 b0.14 a
Samsun6.52 b0.24 a2.61 a84.56 a5.83 c0.00 b0.11 a0.13 b
Significance*****************
LSD (0.05)0.650.030.273.290.380.0010.0010.004
Giresun5.51 b0.00 c2.48 a84.73 a7.28 c0.000.000.00
TombulOrdu5.73 b0.15 b2.27 a81.25 b10.60 a0.000.000.00
Samsun8.05 a0.25 a2.43 a80.40 b8.87 b0.000.000.00
Significance******ns****---
LSD (0.05)0.650.030.243.280.36---
*: p < 0.05; **: p < 0.01; ***: p < 0.001; ns: not significant. z: The differences between mean values on the same column with the same letter were not significant (p < 0.05).
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.

Share and Cite

MDPI and ACS Style

Kurt, H.; Karakaya, O. Geographical Origin Affects the Nut Traits, Bioactive Compounds, and Fatty Acid Composition of Turkish Hazelnut Cultivars (Corylus avellana L. cvs. Çakıldak, Palaz, and Tombul). Horticulturae 2025, 11, 987. https://doi.org/10.3390/horticulturae11080987

AMA Style

Kurt H, Karakaya O. Geographical Origin Affects the Nut Traits, Bioactive Compounds, and Fatty Acid Composition of Turkish Hazelnut Cultivars (Corylus avellana L. cvs. Çakıldak, Palaz, and Tombul). Horticulturae. 2025; 11(8):987. https://doi.org/10.3390/horticulturae11080987

Chicago/Turabian Style

Kurt, Haydar, and Orhan Karakaya. 2025. "Geographical Origin Affects the Nut Traits, Bioactive Compounds, and Fatty Acid Composition of Turkish Hazelnut Cultivars (Corylus avellana L. cvs. Çakıldak, Palaz, and Tombul)" Horticulturae 11, no. 8: 987. https://doi.org/10.3390/horticulturae11080987

APA Style

Kurt, H., & Karakaya, O. (2025). Geographical Origin Affects the Nut Traits, Bioactive Compounds, and Fatty Acid Composition of Turkish Hazelnut Cultivars (Corylus avellana L. cvs. Çakıldak, Palaz, and Tombul). Horticulturae, 11(8), 987. https://doi.org/10.3390/horticulturae11080987

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop