The impact of drying techniques on phenolic compound, total phenolic content and antioxidant capacity of oat flour tarhana

Nurcan Degirmencioglu, Ozan Gürbüz, Emine Nur Herken, Aysun Yurdunuseven Yildiz

Department of Food Technology, Bandırma Vocational High School, Bandırma Onyedi Eylül University, Balıkesir, Turkey.

Abstract

In this study, the changes in phenolic composition, total phenolic content, and antioxidant capacity of tarhanas supplemented with oat flour (OF) at the levels of 20–100% (w/w) after three drying treatments (sun-, oven-, and microwave drying) were investigated. A total of seventeen phenolic standards have been screened in tarhanas, and the most abundant flavonol and phenolic acid compounds were kaempferol (23.62 mg/g) and 3-hydroxy-4-metoxy cinnamic acid (9.60 mg/g). The total phenolic content amount gradually increased with the addition of OF to tarhana, but decidedly higher total phenolic content was found in samples oven dried at 55 °C as compared with other methods. The microwave- and oven dried tarhana samples showed higher TEAC_DPPH and TEAC_ABTS values than those dried with the other methods, respectively, in higher OF amounts. Consequently, oven- and microwave-drying can be recommended to retain the highest for phenolic compounds as well as maximal antioxidant capacity in OF supplemented tarhana samples.

Keywords: Tarhana; Oat flour; Drying; Phenolic compounds; Antioxidant capacity.