Development of Cassava-soy Bean Breakfast Flakes With Improved Protein and Minerals
Muchira, James K
MetadataShow full item record
Cassava production in sub-Saharan Africa, has greatly increased. However, utilization of the roots is hindered by very short shelf life and presence of hydrogen cyanide a natural chemical hazard. Further, cassava roots are poorly endowed with quality protein and minerals despite its versatility to grow in marginalized soils. Consequently, this poses a problem of food loss, serious risk of acute and chronic cyanide poisoning and protein energy malnutrition especially to children under complementary feeding aged 2-5 years whose diets are solely cassava based. Conversely, soy bean has been profiled as a cheap source of quality protein and minerals. However, it also faces utilization challenges due to presence of anti-nutrients such as phytates, tannins and trypsin inhibitors that decreases bioavailability of minerals and palatability. These drawbacks have created a gap in knowledge and hence this study aimed at developing a safe, nutritious, acceptable and shelf stable flaked product by incorporation of soy bean in cassava. A random sampling of the raw materials was done from Muthurwa market, City Park market in Westlands for cassava varieties and Nyamakima market for soy bean. Nutritional profiling of the raw materials was carried out as per standard methods. Further, an experimental design was set up to evaluate most appropriate methods of lowering cyanide in cassava roots to maximum allowable level of 10 mg/kg and anti-nutrients in soy bean to acceptable levels. The most appropriate methods were employed to process the two raw materials. A single Pearson square was used as a tool of formulation to target half of required daily intake of protein requirement for children aged between 2-5 years as recommended by WHO. The following were the formulation with soy bean to cassava ratio respectively; 0:100= Treatment A, 15:85= Treatment B, 25:75= Treatment C, 35:65= Treatment D and 50:50= Treatment E. Descriptive sensory evaluation and overall acceptability was carried out for all the five formulations. In addition, most acceptable sample was packaged in kraft paper, laminated kraft xvi paper and plastic container and accelerated shelf life test, anti-nutritional properties, zinc and iron content were analyzed. Results of proximate analysis for raw materials showed that most of nutritional components of soy bean were significantly higher (p<0.05) compared to the two cassava varieties with exception of carbohydrates. Combination of soaking cassava roots for four days using a ratio of cassava to water of 1:3, pulping and drying in an air oven at 550 C for 3 days (p<0.05) significantly lowered cyanide content by 81 % on average of the two cassava varieties to safe levels. Soaking soy bean for 24 hours in water at a ratio of 1:2, germination for 1 day, drying at 1000 C in an air oven followed by roasting at 2000 C for 5-8 min significantly (p<0.05) lowered anti- nutrients levels by 96.9 %, 20.5 % and 89.8 % for tannins, trypsin inhibitors and phytates respectively compared to control. Proximate composition results of the formulation showed significant increase (p<0.05) in protein, ash, fat and fiber content in formulations as level of soy bean incorporation increased while cyanide content in all formulations was maximum allowable limit of 10 mg/kg. The formulation that had 35:65 soy to cassava ratio had highest scores of sensory evaluation attributes and overall acceptability at (p<0.05). Further, shelf stability, zinc and iron analysis for this formulation was determined. Among the packaging materials laminated kraft paper emerged the most appropriate in minimizing deteriorative factors and hence preserving quality and safety. Cassava soy bean flakes were termed shelf stable for a period of five months but probably could be longer as maximum allowable limits for peroxide values, acid value and microbial stability were not exceeded in the five days of accelerated shelf life test. Zinc and iron content were significantly higher for most acceptable sample compared to the cassava flakes. The current study therefore established that nutritious, safe, acceptable shelf stable can be developed into cassava soy bean flakes and can assist to solve PEM menace.
University of Nairobi