tailieunhanh - Microbiological, steady, and dynamic rheological characterization of boza samples: temperature sweep tests and applicability of the Cox–Merz rule

Boza is a beverage produced by lactic acid bacteria (LAB) and yeast, which affects rheological properties. In the present study, boza samples collected from a local market were characterized with reference to microbiological and rheological approaches. | Turkish Journal of Agriculture and Forestry Turk J Agric For (2014) 38: 377-387 © TÜBİTAK doi: Research Article Microbiological, steady, and dynamic rheological characterization of boza samples: temperature sweep tests and applicability of the Cox–Merz rule 1, 1 1,2 1 Muhammet ARICI *, Nevruz Berna ERSÖZ TATLISU , Ömer Said TOKER , Mustafa Tahsin YILMAZ , 3 1 1 Hasan CANKURT , M. Zeki DURAK , Osman SAĞDIÇ 1 Department of Food Engineering, Faculty of Chemical and Metallurgical Engineering, Yıldız Technical University, İstanbul, Turkey 2 Department of Food Engineering, Faculty of Engineering, Iğdır University, Iğdır, Turkey 3 Department of Food Technology, Safiye Çıkrıkçıoğlu Vocational College, Erciyes University, Kayseri, Turkey Received: Accepted: Published Online: Printed: Abstract: Boza is a beverage produced by lactic acid bacteria (LAB) and yeast, which affects rheological properties. In the present study, boza samples collected from a local market were characterized with reference to microbiological and rheological approaches. The boza samples were characterized with respect to their microbiological population, . the numbers of LAB and yeast. The numbers of LAB and yeast were found to range from × 106 to × 1010 CFU/mL and from × 103 to × 105 CFU/mL, respectively. Their steady and dynamic rheological properties were investigated within the temperature range of 0–50 °C. Apparent viscosity values (η) of the boza samples decreased with shear rate, indicating that the samples behaved as a pseudoplastic fluid. The Ostwald–de Waele model satisfactorily described (R2 > ) the flow behavior of the samples at 5 and 20 °C. Storage modulus (G′) values were higher than loss modulus (G″), indicating that boza samples had a solid-like structure. Temperature had a remarkable effect on the steady and dynamic properties of the .