Abstract
The vane method in controlled shear stress mode was used to determine the yield stress and the shear rate—shear stress data of tomato purees containing 10–35% pulp of two different average particle sizes: 0.34 and 0.71 mm. Consistency index and apparent viscosity increased significantly with pulp content and decreased with average particle size. The effect of pulp weight fraction (P) on relative viscosity (ηr) could be described by the single parameter equation: ηr= [1 – (P/A)]−2, while the effect of particle diameter on ηr could be described using Peclet number. Magnitudes of yield stress determined directly by the vane method were higher than those obtained by using the Casson model, and were proportional to the square of pulp content. Reduced Casson yield stress—P data on purees of both particle sizes followd a single curve. Effects of pulp content and particle size on vane yield stress and apparent viscosity were evident from the correlation forms with high values of R2.
Original language | English |
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Pages (from-to) | 421-436 |
Number of pages | 16 |
Journal | Journal of Texture Studies |
Volume | 25 |
Issue number | 4 |
DOIs | |
State | Published - Dec 1994 |