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2008

Selected Works

Professor Emmanuel Ohene Afoakwa

Articles 1 - 11 of 11

Full-Text Articles in Life Sciences

Melamine Contamination Of Infant Formula In China: The Causes, Food Safety Issues And Public Health Implications, Emmanuel Ohene Afoakwa Nov 2008

Melamine Contamination Of Infant Formula In China: The Causes, Food Safety Issues And Public Health Implications, Emmanuel Ohene Afoakwa

Professor Emmanuel Ohene Afoakwa

No abstract provided.

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Modelling Tempering Behaviour Of Dark Chocolates From Varying Particle Size Distribution And Fat Content Using Response Surface Methodology, Emmanuel Ohene Afoakwa, Alistair Paterson, Mark Fowler, Joselio Vieira Sep 2008

Modelling Tempering Behaviour Of Dark Chocolates From Varying Particle Size Distribution And Fat Content Using Response Surface Methodology, Emmanuel Ohene Afoakwa, Alistair Paterson, Mark Fowler, Joselio Vieira

Professor Emmanuel Ohene Afoakwa

Central Composite Rotatable Design (CCRD) for K=2 was used to study the combined effects of multi-stage heat exchangers for Stages 1 (14–30 °C) and 2 (12–28 °C) coolant temperatures at constant Stage 3 coolant and holding temperatures during tempering of dark chocolates using laboratory-scale mini-temperer. Quantitative data on chocolate temper index (slope) were obtained for products with varying particle size distribution (PSD) (D90 of 18, 25, 35 and 50 μm) and fat (30% and 35%) content. Regression models generated using stepwise regression analyses were used to plot response surface curves, to study the tempering behaviour of products. The results showed …

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Flavor Formation And Character In Cocoa And Chocolate: A Critical Review, Emmanuel Ohene Afoakwa, Alistaiar Paterson, Mark Fowler, Angela Ryan Aug 2008

Flavor Formation And Character In Cocoa And Chocolate: A Critical Review, Emmanuel Ohene Afoakwa, Alistaiar Paterson, Mark Fowler, Angela Ryan

Professor Emmanuel Ohene Afoakwa

Chocolate characters not only originate in flavor precursors present in cocoa beans, but are generated during post-harvest treatments and transformed into desirable odor notes in the manufacturing processes. Complex biochemical modifications of bean constituents are further altered by thermal reactions in roasting and conching and in alkalization. However the extent to which the inherent bean constituents from the cocoa genotype, environmental factors, post-harvest treatment and processing technologies influence chocolate flavor formation and relationships with final flavor quality, has not been clear. With increasing speciality niche products in chocolate confectionery, greater understanding of factors contributing to variations in flavor character would …

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Characterization Of Melting Properties In Dark Chocolates From Varying Particle Size Distribution And Composition Using Differential Scanning Calorimetry, Emmanuel Ohene Afoakwa, Alistair Paterson, Mark Fowler, Joselio Vieira Jul 2008

Characterization Of Melting Properties In Dark Chocolates From Varying Particle Size Distribution And Composition Using Differential Scanning Calorimetry, Emmanuel Ohene Afoakwa, Alistair Paterson, Mark Fowler, Joselio Vieira

Professor Emmanuel Ohene Afoakwa

Melting properties in dark chocolates processed from varying particle size distribution (PSD), fat and lecithin content were studied using differential scanning calorimetry (DSC). Compositional parameters were 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%) contents. Variations in PSD had no influence on crystallinity of products. Fat and lecithin content influenced the degree of crystallinity and melting properties (Tend, Tindex and DHmelt) of the products. Increasing fat content caused consistent increases in degree of crystallinity and crystal size distribution, thus effecting significant changes in Tend, …

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School Feeding Programmes In Africa - A Case Study, Emmanuel Ohene Afoakwa Jul 2008

School Feeding Programmes In Africa - A Case Study, Emmanuel Ohene Afoakwa

Professor Emmanuel Ohene Afoakwa

No abstract provided.

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Effects Of Tempering And Fat Crystallisation Behaviours On Microstructure, Mechanical Properties And Appearance In Dark Chocolates, Emmanuel Ohene Afoakwa Jun 2008

Effects Of Tempering And Fat Crystallisation Behaviours On Microstructure, Mechanical Properties And Appearance In Dark Chocolates, Emmanuel Ohene Afoakwa

Professor Emmanuel Ohene Afoakwa

No abstract provided.

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Factors Influencing Quality Charateristics Of Chocolate Systems During Industrial Manufacture, Emmanuel Ohene Afoakwa Jun 2008

Factors Influencing Quality Charateristics Of Chocolate Systems During Industrial Manufacture, Emmanuel Ohene Afoakwa

Professor Emmanuel Ohene Afoakwa

No abstract provided.

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Effects Of Tempering And Fat Crystalization Behaviours On Microstructure, Mechanical Properties And Appearance In Dark Chocolate Systems., Emmanuel Ohene Afoakwa, Alistaiar Paterson, Mark Fowler, Joselio Vieira Jun 2008

Effects Of Tempering And Fat Crystalization Behaviours On Microstructure, Mechanical Properties And Appearance In Dark Chocolate Systems., Emmanuel Ohene Afoakwa, Alistaiar Paterson, Mark Fowler, Joselio Vieira

Professor Emmanuel Ohene Afoakwa

Fat crystallisation behaviours in dark chocolates from varying particle size distribution (PSD) (D90 of 18, 25, 35 and 50 µm) was studied, yielding products from different temper regimes (optimal temper, over-temper and under-temper), and their effects on mechanical properties and appearance evaluated. Microstructures of derived products were determined using stereoscopic binocular microscopy. Wide variations in mechanical properties and appearance were noted in products from different particle size and temper regimes. Particle size (PS) was inversely related with texture and colour, with the greatest effects noted in hardness, stickiness and lightness at all temper regimes. Over-tempering caused significant increases in product …

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Building Sustainable Agricultural Development Through Home-Grown School Feeding - The African Approach, Emmanuel Ohene Afoakwa, Linley Chiwona-Karltun Apr 2008

Building Sustainable Agricultural Development Through Home-Grown School Feeding - The African Approach, Emmanuel Ohene Afoakwa, Linley Chiwona-Karltun

Professor Emmanuel Ohene Afoakwa

Proper nutrition is critical for optimal growth, cognitive development, general well-being and academic performance of children. Access to good nutrition either at home or through the educational system can contribute to the elimination of malnutrition and its associated health and developmental problems. In this regard, The 2005 UN World Summit recommended the expansion of local school feeding programmes, using home-grown foods where possible as one of the “Quick impact initiatives” to achieve the Millennium Development Goals, especially for rural areas facing the dual challenge of high chronic malnutrition and low agricultural productivity.

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Relationship Between Rheological, Textural And Melting Properties Of Dark Chocolate As Infuenced By Particle Size Distribution And Composition, Emmanuel Ohene Afoakwa, Alistair Paterson, Mark Fowler, Joselio Vieira Feb 2008

Relationship Between Rheological, Textural And Melting Properties Of Dark Chocolate As Infuenced By Particle Size Distribution And Composition, Emmanuel Ohene Afoakwa, Alistair Paterson, Mark Fowler, Joselio Vieira

Professor Emmanuel Ohene Afoakwa

In dark chocolate, rheological properties during processing are influenced by particle size distribution (PSD), fat and lecithin contents with consequential effects on finished texture and melting characteristics. Multivariate regression, correlation and principal component analyses (PCA) were used to explore their interrelationships. A 4 x 3 x 2 factorial experiment was conducted with varying PSD [D90 (90% finer than this size) of 18ìm, 25ìm, 35ìm and 50ìm), fat (25%, 30% and 35%) and lecithin (0.3% and 0.5%). Rheological properties (yield stress and apparent viscosity), textural properties (firmness, index of viscosity and hardness) and melting index (duration) were respectively measured using shear …

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Particle Size Distribution And Compositional Effects On Textural Properties And Appearance Of Dark Chocolates, Emmanuel Ohene Afoakwa, Alistair Paterson, Mark Fowler, Joselio Vieira Feb 2008

Particle Size Distribution And Compositional Effects On Textural Properties And Appearance Of Dark Chocolates, Emmanuel Ohene Afoakwa, Alistair Paterson, Mark Fowler, Joselio Vieira

Professor Emmanuel Ohene Afoakwa

Particle size distribution (PSD) and composition in dark chocolate were varied and their effects on textural properties of molten and tempered chocolates determined using a TA.HD Plus Texture Analyzer. Surface colour was evaluated in terms of CIELAB parameters L*, C* and h° using a HunterLab Miniscan Colorimeter. Compositional parameters for particle size distribution were [D90 (>90% finer) of 18 ìm, 25 ìm, 35 ìm and 50 ìm], fat (25%, 30% and 35%) and lecithin (0.3% and 0.5%) contents. Results showed that PSD, fat and lecithin content significantly (p<0.05) influenced the textural parameters with significant interactions among factors. Particle size was inversely correlated with firmness (1235 - 173 g), consistency (50410 - 7029 g.s), cohesiveness (1594 - 262 g), index of viscosity (5737 - 1099 g.s) and hardness (7062 - 5546 g) with chocolates containing 25% fat and 0.3% lecithin. With higher fat and lecithin contents, PSD influence was reduced. PSD and fat concentration inversely influenced all colour measurements (L*, C* and h°) of samples. High correlations (r = 0.71 – 1.00, P<0.001) were observed between texture parameters and colour. It was concluded that PSD, fat and lecithin contents and their interactions were central to changes in textural properties and appearance during processing of dark chocolates.

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