Transient rheometry

Wissbrun, Kurt F.

doi:10.1007/978-94-011-4934-1_13

Cited by 1 publication

(2 citation statements)

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“…1. Although the test setup is semiempirical because of ill‐defined equilibrium conditions (Wissbrun 1998) and because the results depend largely on shear rate acceleration (Rohm 1992) or instrumental setup (Whorlow 1992), this test has frequently been used for the determination of shear rate dependency and structure degradation of shear‐thinning, time‐dependent, viscoelastic fluids such as yogurt (e.g., Basak and Ramaswamy 1994; Afonso and Maia 1999; Hassan et al. 2003).…”

Section: Resultsmentioning

confidence: 99%

“…1. Although the test setup is semiempirical because of ill-defined (Wissbrun 1998) and because the results depend largely on shear rate acceleration (Rohm 1992) or instrumental setup (Whorlow 1992), this test has frequently been used for the determination of shear rate dependency and structure degradation of shear-thinning, time-dependent, viscoelastic fluids such as yogurt (e.g., Basak and Ramaswamy 1994;Afonso and Maia 1999;Hassan et al 2003). A rapid stress increase at the beginning of the test was followed by a sudden decrease of the slope of the σ γ − profiles, and for γ > 50 s , the slope declined continuously until the end of the upward cycle.…”

Section: Effects Of Cross-linking On Yogurt Viscositymentioning

confidence: 99%

See 1 more Smart Citation

Enzymatic Modification Through Microbial Transglutaminase Enhances the Viscosity of Stirred Yogurt

Jaros¹,

Heidig

Rohm

2007

Journal of Texture Studies

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Among others, dairy proteins and, especially, the caseins are well‐suited substrates for enzymatic modification by microbial transglutaminase. Apart from studies on chemically acidified dairy gels, some research has been performed on the impact of cross‐linking on rheology and texture of set yogurt. In this study, stirred yogurt was produced from skim milk that was incubated with transglutaminase. Dry matter of the base milk and starter cultures were varied at two levels, and the products were analyzed after 2 and 9 d of storage. The rheological measurements revealed a significant but shear rate‐dependent impact of enzymatic cross‐linking on the properties of stirred yogurt. Under steady‐shear conditions, the viscosity‐enhancing effect was more pronounced at low shear rates or shear stresses, pointing on enhanced interactions among the aggregated proteins in the products made from cross‐linked milk. The cross‐link‐induced viscosity‐enhancing effect diminished with increasing shear rates. PRACTICAL APPLICATIONS Microbial transglutaminase represents an interesting tool for texture modification of protein‐containing foods. The formation of new covalent cross‐links among and within protein molecules generates considerable changes in the technofunctional properties of the final products. Acid gels, such as yogurt, made from enzyme‐treated milk are characterized by reduced syneresis and improved viscosity. A better understanding of the enzyme‐catalyzed impact on the rheological behavior of stirred yogurt may help create new products with interesting properties.

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