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ŠUMARSKI LIST 1-2/2023 str. 74     <-- 74 -->        PDF

compositions of the cultivars, the lowest- highest values were reported to be in the range of 50.81-66.29% for fat content, 7.03-24.61% for protein, 7.82-21.79% for carbohydrate, and 2.00-5.20% for ash. In terms of the composition of fatty acids, cultivars of common hazelnuts have oleic acid (69.30-83.59%), linoleic acid (7.57-15.0%), palmitic acid (4.80-9.60%) and stearic acid (1.75-4.10%), as indicated according to investigated studies in the review (Köksal et al. 2006; Oliveira et al. 2008; Bacchetta et al. 2013; Rezaei et al. 2014; Vujevic et al. 2014; Rovira et al. 2017; Wang et al. 2018; Król et al. 2019). Turkish hazel kernels are similar in fat, protein, and ash content, oleic acid, linoleic acid, palmitic acid, and stearic acid to common hazel kernels.
According to the correlation analysis of chemical characteristics of studied Turkish hazel populations shown in Table 7; there is a significantly negative correlation between fat and protein content. It was determined that oleic acid, one of the major fat acids, has a significant negative correlation with ash, linoleic acid, PUFA and a significantly positive correlation with stearic acid, arachidonic acid, SAFA, MUFA. Linoleic acid, another one of the major fat acids, was monitored a significant negative correlation between palmitic acid, palmitoleic acid, stearic acid, oleic acid, arachidonic acid, SAFA and MUFA while a significantly positive correlation was determined between α- linolenic acid, eicosenoic acid and PUFA. Significant negative and positive correlations were observed between the other chemical characteristics (Table 7). In addition, a study on C. avellana reported similar correlations between some parameters of fatty acids (Çetin et al. 2020).
It is well known that unsaturated fatty acids have an important effect on human health and nutrition (Oster et al. 1980; Salonen et al. 1988; Sabate et al. 1993; Kris-Etherton et al. 2001). Namely, the fatty acid profile of hazelnuts, which is high in unsaturated fatty acids such as oleic acid and low in saturated fatty acids, increases the high-density lipoprotein (HDL) in the blood, contributing to lower cholesterol and therefore reduced risk of coronary heart disease (Sabate et al. 1993; Richardson 1996; Alphan et al. 1997; Kris-Etherton et al. 2001). Turkish hazel kernels are rich in unsaturated fatty acids and their consumption will have similar health benefits as the common hazel kernels.
In the fruits of woody plant species, the morphometric and chemical characteristics of the fruit have attracted attention over the years and gained importance in terms of different usage areas (Martins et al. 2017). The wide geographic variation can significantly affect the fruit and seed chemical composition as well as the fruit and seed morphological traits of wild (Izhaki et al. 2002; Yanar et al. 2011; Poljak et al. 2021a, 2022; Sun 2021) and cultivated populations (Poljak et al. 2016, 2021b). It can be said that the morphological and chemical differences between the populations depend on the interactions of factors such as habitat conditions and geographical origin.
CONCLUSIONS
ZAKLJUÈCI
This study provided results that allowed for the first time to determine the morphological and chemical characteristics of Turkish hazel populations in different regions in Turkey. Statistically significant differences between the populations studied were detected.
It was found out that the Sultandağı population had the highest values in terms of morphological characteristics among the studied populations (fruit width, fruit thickness, fruit weight, shell thickness, kernel width, kernel thickness, kernel weight and shell weight). Contrarily, the same population was characterized with the second lowest kernel rate. At the same time, morphological values were lowest in Tosya and Mengen populations, which have the highest kernel rate among the studied populations.
The correlation analysis revealed that the kernel ratio is in a significant negative correlation with shell weight, shell thickness, fruit thickness, fruit weight, and fruit width.
The highest fat content was recorded in the Seben population, and the lowest in the Mengen and İskilip populations. However, this was the opposite when we take into the consideration the protein values, Mengen and İskilip populations have the highest protein content and Seben the lowest. The significant negative correlation between fat and protein values also confirmed these results.
At the end it is important to highlight that besides the food and pharmaceutical industry, Turkish hazelnuts are preferred by the people of the region for its more delicious and aromatic taste than the common hazelnuts. The research is continuing by our team on the physiological characteristics and storage conditions of this hazel species.
ACKNOWLEDGMENT
ZAHVALA
This research was supported by the project number 221O141 of the Scientific and Technological Research Council of Turkey (TUBİTAK).
REFERENCES
LITERATURA
Açkurt, F., M. Özdemir, G. Biringen, M. Löker, 1999: Effects of geographical origin and variety on vitamin and mineral composition of hazelnut (Corylus avellana L.) varieties cultivated in Turkey. Food Chem., 65 (3): 309-313. doi:10.1016/s0308-8146(98)00201-5
Aksoy, N., 2018: Corylus L. (Ed. Ü. Akkemik) Türkiye’nin Doğal-Egzotik Ağaç ve Çalıları. Orman Genel Müdürlüğü Yayınları. Ankara, Turkey: pp. 210-212.
Alaca, F.G., O. Arabacı, 2005: Bazı Tıbbi Bitkilerde Doğal Antioksidanlar ve Önemi. Türkiye Vl. Tarla Bitkileri Kongresi. Cilt 1. Antalya.