Introduction

Cassava (Manihot esculenta) was introduced in Ethiopia around 1960‘s and has been cultivated in the southern and southwestern regions for decades as an alternative food insecurity crop (Taye, 2000; Desse and Taye, 2001). Processing methods, storage experience and modes of consumption are not yet customized unlike most of cassava producing and consuming African countries. Cassava is one of the underutilized root crops in the country. The crop has been used in south western areas of Ethiopia mainly to tackle seasonal food shortage. Currently, some cassava varieties are being promoted in food insecure northern areas of Ethiopia. However, the distribution of the cultivars is not supported with proven food preparation techniques to increase nutrient density and cyanogenic free cassava-based foods without affecting consumers taste. The main purpose of this paper is therefore to develop new value-added products of cassava and to provide improved techniques of processing cassava at rural household level. This study also assesses the nutrient composition and sensory properties of flour blends prepared from cassava, bread wheat, tef, maize, sorghum and finger millet. In addition to this, the study trains model female and male farmers, DAS and small-scale enterprises on the preparation‚ post-harvest handling and utilization of different recipes of cassava at rural household level and also to taste cassava flour for suitability to different recipe makings.

Materials and Methods

Description of study areas

The experiment was conducted in major cassava growing areas in Semen Ari Woreda, South Omo Zone, and Southern Ethiopia. The Woreda lies between 6.08 to 6.27’ N latitude and 36.54 to 36.75’ E longitude. The elevation of the areas ranges from 501 to 3500 meter above sea level. The annual average rainfall of the district ranges between 1401-1600 mm with minimum and maximum annual temperature of 10.1 and 25 ⁰C (CSA, 2007). According to information gathered from key informants and secondary source almost half of the study population faces poor consumption. The study districts are among the most cassava growing areas in Ethiopia.

Site and farmer selection

The experiment was conducted in major cassava growing areas in Semen Ari Woreda, South Omo Zone, Southern Ethiopia. For demonstration site selection was conducted considering relative land area allocated for cassava growing, number of cassava growers, accessibility and engagement in other research projects. Based on the above criteria, 10 Kebles from Semen Ari woreda was selected. Following the site identification, selecting the participating farmers at all sites was done. Selection of the farmers was done based primarily on farmer land covered with cassava, production status and willingness to participate in the research.

Sample collection
The samples were collected from 2 years age of cassava plant roots (5kg from each variety) directly from farming plots of volunteer farmers and Jinka agricultural research center. The soil is removed and packed in polyethylene bags until brought to laboratory. Kulle varieties were used for analysis and demonstration.

Sample preparation
The samples were peeled and chopped for the analysis of cyanide and moisture content within 24 hour. A duplicate portion was sun dried and grounded for preparation of cassava based Ethiopian traditional recipes. To reduce the cost of research Jinka on station laboratory was selected for recipe preparation. The selection was conducted based on low cyanide level observed, witnessed production yield and high geographical distribution of the variety.

The research was under taken to develop and popularize new value added food products of cassava using the released variety namely kulle. Different composite flours from cassava and local cereals such as teff, wheat, maize, sorghum and finger millet were prepared. Cassava flour and different food recipes of cassava like cassava injera, cassava bread, cassava cookies, cassava dabokollo, traditional (local) foods like fossie (aybeza) and other traditional (local) beverages like arki and borde mixed with cereals in different proportions and in sole were prepared. Then their palatability was tested. Each product was packed in plastic bags and stored at room temperature for shelf life determination.

Nutrient analysis
Moisture content was estimated by (AOAC 930.15, 2005). Protein contents were determined by (AOAC 2001.11, 2016). Fat contents were determined by (AOAC 2003.06). Crude fiber was determined by the standard method of (AOAC 962.09, 2016 ES ISO 5498:2002). Crude ash was determined by the standard method of (AOAC 923.03). The values for carbohydrate was given as “total carbohydrate by difference“, that is the sum of the figures formed from moisture, protein, ash and fat subtracted from 100. Iron and Zinc (Fe and Zn) was determined by AOAC Official method 985.35. Fat soluble Vitamins (Vitamin A) were determined by HPLC. Phytate content was determined by latta and Eskin method. Tannin content was determined by burns method.

Sensory evaluation test
Six types of Ethiopian traditional recipes were prepared. 60% cassava was blended with 40 % teff, wheat, maize, sorghum and finger millet for preparing Injera, bread, fossie, borde and arki. Sensory evaluation tests and other relevant data was collected and recorded.  The parameters (quality attributes) measured for evaluation of each product quality were color, texture, physical appearance, taste, after taste, flour size, cooking quality, digestibility and general acceptance. 25 untrained panelists were used to evaluate the product. To quantify the level of sensory attributes 9-point hedonic scale was used with “1” corresponding to “extremely disliked” and “9” corresponding to “extremely liked”. The data was entered and analyzed using spss ver 20.

Results

Proximate composition of cassava-based food recipes

Moisture content
The moisture content for each cassava based food recipes was ranged between 9.43 and 10.49%. The highest moisture content was recorded in 100% cassava flour while the least moisture content was observed in 60% cassava flour and 40% sorghum flour blend ratio (Table 1). Moisture content of cassava flour was decreased when it was blended with different cereal crops (maize, wheat, sorghum and finger millet) in different proportion. However, our result is slightly greater than the recommended moisture content (<5%) by CODEX CAC/GL 08. 1991). This may be because of steeping and drying methods employed during the preparation of flour (Gausman et al., 1951).

Crude protein content
The protein content for each cassava based food recipes had ranged from 1.66–5.83%. The highest protein content was recorded in blend of 60% cassava flour and 40% wheat flour blend ratio and the least was found in 100 % cassava flour only. Protein content was increased with increasing the proportion of wheat flour and decreased with increasing the proportion of cassava flour only (Table 1). The difference could be due to the difference in blending ratio and crop types used during the formulation. According to Gibson and Hotz (2001), blending of cereal-based foods and their processing methods can improve the protein content of the flour. The required daily allowance for protein contents in the complementary foods is ≥15% (WHO/ FAO 2004). However, in our finding, this result can be satisfied when the proportion of pea in the blend is greater than 27%. This suggests that increasing of the pea can improve the protein content of complementary processed foods (Barac et al. 2010).

Crude fat
The fat content for each cassava food recipes had ranged from 1.1 to 2.54%. The highest fat content was recorded in the blend of 60% cassava flour and 40% maize flour blend ratio and the least was found in 100 % cassava flour only. The crude fat content was increased with increasing the proportion of maize flour and decreased with the increasing the proportion of cassava flour only (Table 1). In addition, our result is less than the daily recommended fat content in complementary foods range from 10 to 25% (WHO/ FAO 2004). This is may be due to the differences in crop types used and the processing methods employed during the formulation of the flour. For instance, the processing methods (removal of outer part of maize and germ) have significant effect on reduction in fat content (Arif et al., 2011). In case of our finding, increasing the maize content can improve the fat content of complementary processed food.

Crude fiber
The crude fiber content in cassava-based food recipes were ranged from 1.4– 3.0%. The high crude fiber content was recorded in the blended ratio of 60% cassava flour and 40% finger millet flour while the least fiber content was recorded in 60% cassava flour and 40% wheat flour blended ratio (Table 1). The daily recommended allowance of crude fiber in the complementary food is <5%. Thus, all the complementary foods processed in this study meet this requirement.

Total ash
The total ash content in cassava based food recipes were ranged in between 1.68 % and 2.31%. The highest ash content was recorded in 100% cassava flour only and least ash content was observed in 60 % cassava flour and 40% wheat flour blends respectively (Table 1). All the complementary foods processed in this study meets the recommended ash content by WHO/FAO (2004) in the complementary food (<5 g/100 g).

Carbohydrates
The carbohydrate contents in cassava-based food recipes had ranged from 77.87–81.63%. The highest carbohydrate content was observed in 100% cassava flour only while the least carbohydrate content was seen in the blended ratio of 60% cassava flour and 40% maize flour (Table 1). With the increasing of cassava flour content in the blend, the carbohydrate content was found to be increased. Processing method like dehusking may increases carbohydrates content in the diet (Abiodun and Adepeju 2011). All the complementary foods processed in this work meet the carbohydrate content recommended by WHO/ FAO (2004) in the complementary food (≥65 g/100 g).

Energy
The energy (caloric) content of cassava-based food recipes was ranged between 343.06–356.35 kcal/100 g. The highest energy content was observed in 60% cassava flour and 40% sorghum flour blended ratio and the least energy content was observed in 100% cassava flour only (Table 1). Energy content increased with the increasing of sorghum flour in cassava-based food recipes. However, the result is less than the recommended energy content by WHO/ FAO (2004) in the complementary foods (400–425 kcal/100 g). This may be due to the less fat content of the raw materials used in the formulation of the food.

CF=Cassava flour, TF=Tef flour, WF= Wheat flour, MF= Maize flour, SF=Sorghum flour, FMF= Finger millet flour

Vitamin A and mineral content of cassava-based food recipes

Vitamin A contents of all of the products were not detected. The major reason is the insolubility of vitamin A in water, thus vitamin A does not dissolve in water but slightly soluble in alcohol, fat, oil and soluble in organic solvents like ether. The iron content of the samples varied from 22.15 to 59.85 mg/kg. The lowest value of iron was contained in 100% cassava flour only but 60% cassava flour and 40% tef flour had highest in iron content. The zinc content of the products varied from 6.14 to 13.24 mg/kg. Sixty (60%) cassava flour and 40% tef flour contained high zinc content whereas 100% cassava flour only contained the lowest.

CF=Cassava flour, TF=Tef flour, WF= Wheat flour, MF= Maize flour, SF=Sorghum flour, FMF= Finger millet flour

Anti-nutritional content of cassava-based food recipes

The phytate content of the products was between 85.87 & 142.39 mg/100g. The highest value of phytate was contained in 60% cassava flour and 40% tef flour but the least was detected in 60% cassava flour and 40% wheat flour. The tannin content of the products was not detected except in 60% Cassava flour and 40% Sorghum flour. Phytate is good metal chelator and prevents absorption minerals by the intestine, which has negative nutritional impact on metals necessary for good health especially iron and calcium.

CF=Cassava flour, TF=Tef flour, WF= Wheat flour, MF= Maize flour, SF=Sorghum flour, FMF= Finger millet flour

Training

Practical training on processing, postharvest handling and utilization of cassava flour was given for 20 development agents,  18 keble administrators, 121 model female farmers and 60 model male farmers.

Promotion

Promotional materials such as brochures and preparation guidelines was prepared and distributed to farmers for promoting awareness about cassava utilization. Mini exhibition (field day) was prepared to farmers for promoting awareness about cassava utilization.

Conclusion

The study was evaluated the nutritional and anti-nutritional attributes of Cassava based recipes from flour blends of bread wheat, tef, sorghum and finger millet. Based on our finding, the total moisture content, crude protein, crude fiber, crude fat, ash, carbohydrate and energy of cassava based food recipes had ranged between 9.43–10.49%, 1.66–5.83%, 1.4–3.0%, 1.1–2.54%, 1.68–2.31%, 77.87–81.63% and 343.06-356.35kcal/100g, respectively. The formulated cassava based recipes were contained higher protein and lower phytate and tannin contents than Codex recommended level. The use of bread wheat, tef, sorghum and finger millet blends in cassava based recipes can greatly enhance the protein content, without compromising consumer acceptance. This study showed that nutrient dense cassava based recipes could be produced from bread wheat, tef, sorghum and finger millet than using cassava flour alone.