Phd Degree / Doktora

Permanent URI for this collectionhttps://hdl.handle.net/11147/2869

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Publisher: search.filters.publisher.Izmir Institute of TechnologySubject: search.filters.subject.Hazelnut

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  • Doctoral Thesis
    Molecular Genetik Analysis in Hazelnut (corylus Avellana)
    (Izmir Institute of Technology, 2017) Öztürk, Süleyman Can; Doğanlar, Sami; Doğanlar, Sami; 04.03. Department of Molecular Biology and Genetics; 04. Faculty of Science; 01. Izmir Institute of Technology
    European hazelnut (Corylus avellana L.), cultivated in several areas of the world including Europe, Anatolia, and the USA, is an economically important nut crop due to its high mineral, oleic acid, amino acid, and phenolic compound content and pleasant flavor. This study examined molecular genetic diversity and population structure of both Slovenian and Turkish hazelnuts. In the first part of the work, genetic diversity of 54 wild accessions and 48 cultivars from the Slovenian national hazelnut collection was determined using amplified fragment length polymorphism (AFLP) and simple sequence repeat (SSR) markers. The accessions were also characterized for ten nut and seven kernel traits and some wild accessions were shown to have breeding potential. An association mapping panel composed of 64 hazelnut cultivars and wild accessions had considerable variation for the nut and kernel quality traits. Morphological and molecular data were associated to identify markers controlling the traits. In all, 49 SSR markers were significantly associated with nut and kernel traits [P < 0.0001 and LD value (r2) = 0.15–0.50]. This work is the first use of association mapping in hazelnut and has identified molecular markers associated with important quality parameters in this important nut crop. In the second part of the work, 402 Turkish hazelnut accessions were screened with 30 SSR markers. The data obtained from this screen allowed selection of a national core collection of hazelnut. This core collection represents a maximum of genetic diversity in a minimum number of individuals. Turkish cultivar ‘Tombul’ was sequenced using next generation sequencing technology and new SSR markers were developed. It was found that seven SSR markers were sufficient to discriminate Turkish hazelnut cultivars from each other. This study provides molecular information for marker-assisted selection in hazelnut and gives new insight to discover the genetic potential of hazelnut germplasm.
  • Doctoral Thesis
    Prebiotic Oligosaccharide Production From Hazelnut Wastes
    (Izmir Institute of Technology, 2017) Sürek, Ece; Büyükkileci, Ali Oğuz; Büyükkileci, Ali Oğuz; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    Turkey is the world leader in hazelnut production and a large amount of wastes is produced during its harvesting and processing. Obtaining valuable products from hazelnut by-products can add value to those. In this study, xylooligosaccharide (XOS), which has prebiotic potential and not manufactured in Turkey, was selected as the target product. Hazelnut wastes (shell, green leafy cover and pruning wastes) are suitable sources for production of XOS. Although there are some studies on valorization of hazelnut wastes, there is no study about XOS production. In this study, xylan in the shell was hydrolyzed to XOS by autohydrolysis and enzymatic hydrolysis at different conditions. The highest XOS yield was obtained as 62.93% after autohydrolysis at 190 oC for 5 min. The content of XOS with low degree of polymerization (DP<6) increased from 10.13 to 32.74% after hydrolysis with xylanase. XOS from enzymatic hydrolysis was purified by ultrafiltration through 10 and 2 kDa size membranes. The percent of low DP-XOS in liquor was increased after ultrafiltration; however monomers could not be separated. Prebiotic activity and stability of XOS were determined under different conditions. The growth of probiotic bacteria was observed after in vitro fermentation of XOS. XOS showed a good stability to food production and gastrointestinal digestion conditions. The objective of this study was to produce of a high value product such as XOS with prebiotic potential from hazelnut wastes by autohydrolysis and enzymatic hydrolysis. This study was highly original since XOS has been produced from hazelnut wastes for the first time.