Browsing by Author "Yemis, Oktay"

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Changes in Pigment Profile and Surface Colour of Fig (Ficus Carica L.) During Drying
(Wiley, 2012) Yemis, Oktay; Bakkalbasi, Emre; Artik, Nevzat
In this study, anthocyanins in three fresh fig varieties (Ficus carica L.) cultivated in Turkey were characterised and quantified by HPLC/DAD and HPLC/MS. In addition, the carotenoid composition of Sarilop and Sarizeybek, yellow fig varieties, was determined, and then the ripening- and drying-related changes in carotenoids and surface colour of figs were monitored during conventional sun-drying. Four different anthocyanins, cyanidin-3-glucoside, cyanidin-3,5-diglucoside, cyanidin-3-rutinoside (major anthocyanin) and pelargonidin-3-glucoside, were identified in samples. Lutein, zeaxanthin, beta-cryptoxanthin and beta-carotene were carotenoids in yellow fig varieties. Approximately 80% of carotenoid compounds in yellow fig varieties degraded at the end of drying (i.e. seventh day). L (lightness), a (redness and greenness) and b (yellowness and blueness) colour parameters were measured by Hunter Lab system. Great changes in carotenoid composition and surface colour were observed at ripening stage on tree. A significant reduction in L and b values that refers to browning in figs was made in the first 3 days of drying process.
Changes in the Phenolic Content and Free Radical-Scavenging Activity of Vacuum Packed Walnut Kernels During Storage
(Karger, 2013) Bakkalbasi, Emre; Yilmaz, Ozay Mentes; Yemis, Oktay; Artik, Nevzat
In this study, the effects of storage temperature, O-2 permeability of packaging materials and variety on phenolic content and free radical-scavenging activity of vacuum-packaged walnut kernels were studied over a 12 months storage period. Methyl gallate (23.70 - 93.75 mg/kg), ellagic acid (137.95 - 569.22 mg/kg), and an ellagic acid pentoside (270.59 - 637.17 mg ellagic acid equivalent/kg) were identified in walnut varieties. While a slight decrease in the amount of ellagic acid was observed during 12 months storage, decreases in the amount of ellagic acid pentoside, total phenolic content and free radical-scavenging activity were severe. The present study concluded that it is possible to protect the phenolic content and antiradical activity of walnut kernels by packaging in Polyamide/Polyethylene laminate pouches having an oxygen permeability lower than 63.40 +/- 0.40 (mL/m(2)/24h at 23 degrees C) under vacuum at 20 degrees C up to twelve months.