Response Surface Methodology for Studying the Effects of Feed Moisture and Ingredient Variations on the Chemical Composition and Appearance of Extruded Sorghum-Groundnut-Cowpea Blends

Studies were conducted to evaluate the effects of feed moisture and ingredient variations on the chemical composition and appearance of extruded sorghum-groundnut-cowpea blends using response surface methodology. Central composite rotatable design for k = 3 was used to study the combined effect of feed moisture (12 to 44 percent), groundnut concentration (zero to 10 percent) and cowpea level (zero to 20 percent) on the chemical composition and appearance of extruded ready-to-eat sorghum-legume blends in a single screw extruder. Product moisture, crude protein, crude fat, ash (minerals), crude fibre, carbohydrate and colour (L, a and b-values) were determined on the products using standard analytical methods. The results showed that irrespective of the feed moisture level, the extrusion process could reduce the product moisture to levels between six to 10 percent and low enough to extend the shelf life of the derived products. Increasing additions of cowpea and groundnut resulted in significant increases in protein, fat and ash (minerals - calcium, iron, and phosphorus) contents of the sorghum-legume extrudates. Increasing addition of cowpea decreased the redness of the sorghum extrudates, while no changes were noted with groundnut additions. Contrary, increasing groundnut addition generally increased the yellowness at all cowpea concentrations, while only minimal changes were noted with cowpea additions. The lightness of the sorghum extrudates decreased with increasing cowpea and groundnut concentrations, and this was more pronounced at higher cowpea concentrations and with increasing groundnut levels. The level of feed moisture showed no effect. Models developed for the indices gave R2-values ranging from 67.04 percent (for a-value) to 87.83 percent (for fat content), with insignificant lack of fits indicating the adequacy of the model in explaining the data. The optimal conditions likely to produce ready-to-eat puffed snack with enhanced nutritive value and appearance from sorghum-groundnut-cowpea blend extrudates was at low feed moisture (10 to 14 percent), cowpea level (18 to 20 percent) and groundnut level (six to eight percent).

[1]  M. Ahmedna,et al.  Peanut protein concentrate: Production and functional properties as affected by processing , 2007 .

[2]  R. Guy.  Raw materials for extrusion cooking processes , 1994 .

[3]  J. M. Harper,et al.  Production of nutritious precooked foods in developing countries by low‐cost extrusion technology , 1985 .

[4]  J. Berenji,et al.  Perspectives of Sorghum in Europe , 2004 .

[5]  Micha Peleg,et al.  Extrudate Cell Structure‐Texture Relationships , 1992 .

[6]  António S. Barros,et al.  Protein profile and malt activity during sorghum germination , 2008 .

[7]  J. M. Kordylas.  Processing and preservation of tropical and subtropical foods. , 1990 .

[8]  R. Bernhardt,et al.  Influence of grain germination on functional properties of sorghum flour , 2010 .

[9]  F. Saalia,et al.  Extrusion of Maize–Cowpea Blends in a Modified Oil Expeller , 1997 .

[10]  O. Lawal.  Functionality of African locust bean (Parkia biglobossa) protein isolate: effects of pH, ionic strength and various protein concentrations , 2004 .

[11]  Hildegarde Heymann,et al.  Effect of process conditions on the physical and sensory properties of extruded oat-corn puff , 2000 .

[12]  Yong-Cheng Shi,et al.  Soy protein-fortified expanded extrudates : Baseline study using normal corn starch , 2009 .

[13]  E. Afoakwa,et al.  Influence of spontaneous fermentation on some quality characteristics of maize-based cowpea-fortified nixtamalized foods , 2007 .

[14]  I. Onwueme,et al.  Field crop production in tropical Africa: principles and practice. , 1991 .

[15]  E. Afoakwa,et al.  Application of response surface methodology for studying the product characteristics of extruded rice–cowpea–groundnut blends , 2004, International journal of food sciences and nutrition.

[16]  E. Afoakwa,et al.  Modelling tempering behaviour of dark chocolates from varying particle size distribution and fat content using response surface methodology , 2008 .

[17]  E. Afoakwa,et al.  Effect of spontaneous fermentation and amylase-rich flour on the nutritive value, functional and viscoelastic properties of cowpea-fortified nixtamalized maize , 2010, International journal of food sciences and nutrition.

[18]  H. Daun,et al.  Effects of extrusion conditions on sensory properties of corn meal extrudates , 1991 .

[19]  P. Belton,et al.  Sorghum and millets: protein sources for Africa , 2004 .

[20]  E. Afoakwa,et al.  Application of Response Surface Methodology for Optimizing the Pre-processing Conditions of Bambara Groundnut (Voandzei Subterranea) during Canning , 2007 .

[21]  E. Afoakwa,et al.  Modelling the Effects of Feed Moisture and Ingredient Variations on the Physical Properties and Functional Characteristics of Extruded Sorghum-Groundnut-Cowpea Blends using Response Surface Methodology , 2010 .

[22]  Imran A. Tasadduq,et al.  Response surface methodology: A neural network approach , 1997 .

[23]  E. Afoakwa,et al.  Application of response surface methodology for studying the quality characteristics of cowpea-fortified nixtamalized maize , 2003 .

[24]  A M Joglekar,et al.  Product excellence through design of experiments , 1987 .

[25]  N. D. Frame.  The Technology of Extrusion Cooking , 1993 .

[26]  J. Aguilera,et al.  Changes in the Starch Fraction During Extrusion-cooking of Corn , 1983 .

[27]  Douglas C. Montgomery,et al.  Response Surface Methodology: Process and Product Optimization Using Designed Experiments , 1995 .

[28]  S. G. Uzogara,et al.  PROCESSING and UTILIZATION of COWPEAS IN DEVELOPING COUNTRIES: A REVIEW , 1992 .

[29]  E. Berghofer,et al.  Extrusion Cooking of Rice Flour and Amaranth Blends , 1999 .

[30]  E. Afoakwa,et al.  Effect of Solid State Fermentation on the Physico-Chemical, Functional and Textural Properties of Nixtamalized Maize , 2006 .

[31]  Gustavo V. Barbosa-Cánovas,et al.  Functional and nutritional properties of extruded whole pinto bean meal (Phaseolus vulgaris L.) , 1998 .

[32]  G. Doxastakis,et al.  Study of functional properties of seed storage proteins from indigenous European legume crops (lupin, pea, broad bean) in admixture with polysaccharides , 2005 .

[33]  Robert Balshaw,et al.  Textural optimization of spaghetti using response surface methodology: effects of drying temperature and durum protein level , 1993 .