The Effect of Acoustic Energy on Viscosity and Serum Separation of Traditional Ayran, a Turkish Yogurt Drink (in English)

Öz

The effect of acoustic energy on the rheological behaviour and serum separation during storage of traditional Ayran, which is a mixture of yogurt, water and salt, was investigated. Ayran samples were prepared by the addition of water at a level of 40% (w/w) and salt at a level of 1% (w/w) and stored at 4 °C. They were sonicated for two and four minutes using an ultrasonic generator at a frequency of 20 kHz. The ultrasonic amplitudes used were 40% (22.91W), 60% (33.38W) and 80% (44.54W). Viscosity was measured using a rotational viscometer at the speed of 20, 30, 50, 60, 100 and 200 rpm. The highest apparent viscosity in Ayran was obtained at 44.54 W power level for 4 minutes. In addition, it was obtained that acoustic energy had a significant effect on the serum separation of Ayran. An empirical power-law model was used to describe the rheological behaviour of Ayran samples with regression coefficients between 0.891 and 0.997. Ayran exhibited a pseudoplastic behaviour, non-Newtonian. Keyywords: Acoustic energy, traditional Ayran, viscosity, serum separation

Anahtar Kelimeler

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Geleneksel Ayranın Viskozite ve Serum Ayrılması Üzerine Akustik Enerjinin Etkisi (İngilizce)

Öz

Geleneksel Ayranın reolojik davranışları ve depolama sonrası serum ayrılması üzerine akustik enerjinin etkisi araştırıldı. Ayran örnekleri yoğurda %40 (w/w) su ve %1 tuz (w/w) ilave edilerek hazırlandı. Elde edilen Ayranlara 20kHz frekansta çalışan bir ultrases işlemcisiyle 2 ve 4 dakika ultrases işlemi uygulandı. Ultrases genlik seviyesi %40 (22.91W), %60 (33.38W) ve %80 (44.54W) olarak kullanıldı. Viskozite 20, 30, 50, 60, 100, 200 rpm’de rotasyonel viskozimetre kullanılarak ölçüldü. En yüksek viskozite değeri 4 dakikalık işlem süresinde 44.54 güç seviyesinde elde edildi. Ayrıca, akustik enerjinin ayranın serum ayrılması üzerine önemli bir etkiye sahip olduğu gözlendi. Ayranın reolojik özelliklerini tanımlamak için deneysel power-law modeli kullanıldı. Modele ait regresyon katsayıları 0.891 ve 0.997 arasında değiştiği gözlendi. Ayran Newtoniyal olmayan pseudoplastik bir davranış sergiledi.

Anahtar Kelimeler

• Akustik enerji, geleneksel Ayran, viskozite, serum ayrılması

Kaynakça

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