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Social and Behavioral Sciences Commons

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Selected Works

Agricultural and Resource Economics

Professor Emmanuel Ohene Afoakwa

Response surface methodology

Publication Year

Articles 1 - 4 of 4

Full-Text Articles in Social and Behavioral Sciences

Response Surface Methodology For Studying The Quality Characteristics Of Cowpea (Vigna Unguiculata)-Based Tempeh., George Amponsah Annor, Esther Sakyi-Dawson, Samuel Sefa-Dedeh, Firibu Kwesi Saalia, Dr. Emmanuel Ohene Afoakwa (Phd), Kwaku Tano-Debrah, Agnes Simpson Budu Dec 2009

Response Surface Methodology For Studying The Quality Characteristics Of Cowpea (Vigna Unguiculata)-Based Tempeh., George Amponsah Annor, Esther Sakyi-Dawson, Samuel Sefa-Dedeh, Firibu Kwesi Saalia, Dr. Emmanuel Ohene Afoakwa (Phd), Kwaku Tano-Debrah, Agnes Simpson Budu

Professor Emmanuel Ohene Afoakwa

Response surface methodology was used to optimize the processing conditions in the preparation of cowpea tempeh. The independent factors studied were boiling time (varying from 5 to 30 min), incubation time (varying from 12 to 48 h) and incubation temperatures (varying from 25 to 50°C), whereas the dependent factors were protein content, protein solubility, pH, titratable acidity and total color difference (using L, a* and b*). Regression models were generated and adequacy was tested with regression coefficients (R2) and the lack-of-fit tests. Optimum processing conditions were determined by method of superimposition. There was a strong and significant influence (P < 0.01) of the quadratic effect of the incubation time on the protein content of the cowpea tempeh, with similar significance (P < 0.01) noted in protein solubility with increasing boiling time. The optimum processing conditions observed for the preparation of cowpea tempeh were boiling time of about 20 min, incubation time of about 28 h and incubation temperature of about 37°C.


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 …


Application Of Response Surface Methodology For Studying The Influence Of Soaking, Blanching And Sodium Hexametaphosphate Salt Concentration On Some Biochemical And Physical Characteristics Of Cowpeas (Vigna Unguiculata) During Canning, Emmanuel Ohene Afoakwa, Samuel Yenyi May 2006

Application Of Response Surface Methodology For Studying The Influence Of Soaking, Blanching And Sodium Hexametaphosphate Salt Concentration On Some Biochemical And Physical Characteristics Of Cowpeas (Vigna Unguiculata) During Canning, Emmanuel Ohene Afoakwa, Samuel Yenyi

Professor Emmanuel Ohene Afoakwa

Response surface methodology and central composite design for K = 3 was used to study the combined effect of blanching time (0–12 min), soaking time (0–24 h) and sodium hexametaphosphate [(NaPO3)6] salt concentration (0–1%) on moisture, ash, leached solids, phytates, tannins and hardness (texture) of cowpeas during canning. Regression models were developed to predict the effects of variables on the studied indices. Blanching, soaking and salt concentration all had significant positive effects on moisture content, ash content, leached solids, phytates, tannins and hardness of the canned cowpeas with significant interaction between all the factors with high regression coefficients (72.0–91.4%). The …


Application Of Response Surface Methodology For Studying The Product Characteristics Of Extruded Rice-Cowpea-Groundnut Blends, Emmanuel Asare, Samuel Sefa-Dedeh, Emmanuel Ohene Afoakwa Jul 2004

Application Of Response Surface Methodology For Studying The Product Characteristics Of Extruded Rice-Cowpea-Groundnut Blends, Emmanuel Asare, Samuel Sefa-Dedeh, Emmanuel Ohene Afoakwa

Professor Emmanuel Ohene Afoakwa

Response surface methodology (with central composite rotatable design for k=3 was used to investigate the product properties of extruded rice-cowpea-groundnut blends in a single screw extruder. The combined effect of cowpea (0-20%), groundnut (0-10%), and feed moisture (14-48%) levels were used for formulation of the products. The product moisture, expansion ratio, bulk density and total colour change were studied using standard analytical methods. Well-expanded rice-legume blend extrudates of less bulk density and lower moisture content were produced at low feed moisture. Increasing legume addition affected the various shades of colour in the product. Models developed for the indices gave R2 …