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Professor Emmanuel Ohene Afoakwa

Yield stress

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Full-Text Articles in Food Science

Comparison Of Rheological Models For Determining Dark Chocolate Viscosity, Emmanuel Ohene Afoakwa, Alistair Paterson, Mark Fowler, Joselio Vieira Dec 2008

Comparison Of Rheological Models For Determining Dark Chocolate Viscosity, Emmanuel Ohene Afoakwa, Alistair Paterson, Mark Fowler, Joselio Vieira

Professor Emmanuel Ohene Afoakwa

Parameters in chocolate rheology, namely shear viscosity and yield stress, are important in manufacture and directly influenced by product particle size distribution (PSD) and composition. The Casson model was the standard confectionery industry strategy to quantify rheological properties of molten chocolate until in 2000, the International Confectionery Association recommended the use of interpolation data to describe viscosity. The two strategies are compared and correlated in defining rheological properties of molten dark chocolates prepared using different PSD, fat and lecithin content. Rheological parameters were determined using a shear rate-controlled rheometer and data examined using correlation, regression and principal component analyses to …


Effects Of Particle Size Distribution And Composition On Rheological Properties Of Dark Chocolate, Emmanuel Ohene Afoakwa, Alistair Paterson, Mark Fowler May 2007

Effects Of Particle Size Distribution And Composition On Rheological Properties Of Dark Chocolate, Emmanuel Ohene Afoakwa, Alistair Paterson, Mark Fowler

Professor Emmanuel Ohene Afoakwa

Control of chocolate viscosity is vital to its quality and production cost, and directly influenced by solids particle size distribution (PSD) and composition. Effects of PSD and composition on rheological properties of molten dark chocolate were investigated by varying PSD [D90 (90% finer than this size) of 18, 25, 35 and 50 lm], fat 25, 30 and 35% and lecithin (0.3 and 0.5%) using a shear rate-controlled rheometer. PSD, fat and lecithin content significantly affected all rheological parameters, with significant interaction among factors. Increasing particles size gave significant reductions in Casson plastic viscosity, Casson yield value, yield stress, apparent viscosity …