Dynamic rheological characterization of salep glucomannan/galactomannan-based milk beverages
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Tarih
2009
Yazarlar
Dergi Başlığı
Dergi ISSN
Cilt Başlığı
Yayıncı
Elsevier Sci Ltd
Erişim Hakkı
info:eu-repo/semantics/closedAccess
Özet
The steady flow and viscoelastic properties of glucomannan (salep) and galactomannans (locust bean gum, LBG and guar gum, GG) in milk beverages were investigated at 25 and 50 degrees C. The consistency index (K), flow behavior index (n), yield stress and thixotropic area were measured as functions of steady shear; elastic modulus (G'), loss modulus (G ''), tan delta and complex viscosity (eta*) parameters were derived from oscillatory shear experiments. The steady flow behavior of mannan-based milk beverages was observed to be shear-thinning and thixotropic. Galactomannans exhibited greater shear-thinning and thixotropy than glucomannan in milk beverages. The synergistic effect was detected between salep and LBG with highest thixotropy. Increasing the temperature decreased Casson yield stresses of GG but not salep and LBG samples. Similar viscoelastic behavior was observed between salep and LBG, they could be classified as concentrated solutions but GG showed gel-like structure. At low frequencies, high tan delta values were observed for the salep and LBG samples indicating viscous character. On the other hand, GG sample had nearly the same tan delta values through the frequency sweep. Cox-Merz rule was tested to correlate the steady and dynamic viscosities of samples. It was found that Cox-Merz rule was applicable only to LBG-milk beverage among the studied samples. (C) 2008 Elsevier Ltd. All rights reserved.
Açıklama
Anahtar Kelimeler
Milk beverages, Salep, Glucomannan, Galactomannan, Rheology
Kaynak
Food Hydrocolloids
WoS Q Değeri
Q1
Scopus Q Değeri
Q1
Cilt
23
Sayı
5
