Dynamic Viscoelastic Properties of Foods in Texture Control

Abstract

Small‐amplitude dynamic viscoelastic properties of ten fluid and semisolid food products such as butter, canned frosting, ketchup, and whipped cream cheese have been compared with their respective properties in steady shear. The complex viscosity (η*) and dynamic viscosity (η′) were always found to be larger than steady viscosities (η), resulting in relationships of the form: η*(ω)=C⋅η(γ)α, η′(ω)=C′⋅η(γ)α′ where C and C′ are constants (Pa1−α s1−α, Pa1−α′ s1−α′), α and α′ are constants (dimensionless), ω is the frequency (s−1), and γ is the shear rate (s−1). The primary normal stress coefficient (ψ1) was found to correlate well with G′/ω2 which is larger than ψ1 in all cases, and G′/ω2 can be related to the primary normal stress coefficient by a power relationship of the form: G′/ω2=C*⋅ψ1(γ)α*, where C* is a constant (Pa1−α* s2(1−α*)) and α* is a constant (dimensionless). This makes it possible to relate dynamic viscoelastic properties to steady properties for the fluid and semisolid foods studied.