Phenolic Content and Antioxidant Activities of Green Walnuts Harvested at Different Periods on The Lake Van Coast

Abstract

Walnut (Juglans regia L.) is a nut with high nutritional and economic values. Walnut is commonly used as a functional ingredient in several traditional food products and as a natural source of phytochemicals in pharmacy and cosmetics. Walnut harvested in the immature periods, known as milk walnut, have been used in formulation of some traditional foods.  In this study, phenolic composition and antioxidant activities of green walnuts (immature) harvested from 3 different districts (Van Center, Edremit, and Gevas) around Lake Van in 4 different periods (1^st June, 15^th June, 30^th June, and 15^th July) were investigated. The total phenolic content, DPPH, and ABTS values of green walnuts were 17842.26-6907.83 mg GAE kg^-1, 208.8-49.03 and 208.48-66.97 mmol TE g^-1, respectively. Juglone, gallic acid, neochlorogenic acid, and rutin common phenolic compounds were determined in green walnut samples. While the highest total phenolic content and antioxidant activity were observed in green walnuts harvested on 1^st June, the highest juglone was determined in samples collected on 30^th June. As a result, it was determined that green walnut had high antioxidant activity and phenolic content, especially juglone. The harvesting period considerably affect the phenolic contents of samples. 

Keywords

• Antioxidant activity,Phenolic compound,Juglone,Green walnut

Van Gölü Kıyısında Farklı Dönemlerde Hasat Edilen Yeşil Cevizlerin Fenolik Madde İçerikleri ve Antioksidan Aktiviteleri

Abstract

Ekonomik değeri yüksek bir ürün olan Cevizin (Juglans regia L.), özellikle süt cevizi denilen olgunlaşmamış dönemleri özel fitokimyasalların doğal kaynağı olarak eczacılık ve kozmetikte kullanılmakta, ayrıca bazı geleneksel gıdaların üretiminde de yer almaktadır. Bu çalışmada, Van Gölü çevresinde 3 farklı ilçeden (Van Merkez, Edremit ve Gevaş), 4 ayrı dönemde (1 Haziran, 15 Haziran, 30 Haziran ve 15 Temmuz) toplanan yeşil cevizlerin fenolik bileşimi ve antioksidan aktiviteleri araştırılmıştır. Yeşil cevizlerin toplam fenolik madde miktarı, DPPH ve ABTS analizi sonuçları sırasıyla 6907.83- 17842.26 mg GAE/kg, 49.03-208.8 ve 66.97-208.48 mmol TE/g aralıklarında bulunmuştur. Elde edilen sonuçlara göre yeşil ceviz örneklerinde fenolik bileşiklerden juglon, gallik asit, neoklorojenik asit ve rutin tespit edilmiştir. Hasat edilen yeşil cevizlerde 1 Haziran döneminde toplam fenolik madde miktarı ile antioksidan aktivite miktarının en yüksek olduğu saptanırken, en yüksek juglon miktarı 30 Haziran dönemine ait örneklerde olduğu belirlenmiştir. Çalışma sonucunda yeşil cevizlerin çalışma dönemi içinde başta juglon olmak üzere yüksek fenolik madde içeriğine ve antioksidan aktiviteye sahip oldukları ancak bunların cevizlerin hasat edildiği döneme göre farklılıklar gösterdiği belirlenmiştir. 

Keywords

• antioksidan aktivite,fenolik bileşik,juglon,yeşil ceviz

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