Formulation of an iron biofortified bean-silverfish instant sauce for pregnant women

Abstract

In Uganda, there is an increasing burden of anaemia especially among pregnant women and children aged 6-59 months. Some of the readily available and affordable food to pregnant mothers are beans which have relative amounts of iron but also high levels of phytates which reduce Fe bioavailability. Bio-fortification of beans enhances their iron content which is further complemented with the iron in the silver fish. This study aimed at developing a safe and acceptable iron biofortified bean - silver fish composite sauce to prevent anaemia among pregnant women through improved micronutrient intake. Design expert software was used to generate four composite formulations of iron biofortified bean-silver fish in the ratios of 90:10, 80:20, 70:30 and 100:0, respectively, each contributing more than 70% Recommended Daily Allowance of iron for pregnant women of reproductive age. Commonly used seasonings and spices (tomatoes, garlic, onions and Mchuzi mix) were added in equal proportions to each of the composite formulations. The instant composite flour was produced using extrusion technology and analysed for moisture, crude protein, crude oil, crude ash, carbohydrates, selected minerals, folate, total phytates and aflatoxin levels. Microbiological analysis considered total plate counts, total coliforms, Escherichia coli, yeast and moulds, Salmonella and Staphylococcus aureus. The composite flour was reconstituted into instant sauce with boiling water and evaluated for sensory properties using a panel of 50 semi-trained analysts. Extrusion of iron bio-fortified beans-silverfish instant sauce with the ratio of 80:20 had increased moisture content from 5.84 to 10.33% compared to the raw un-extruded beans. Fortification of extruded NABE beans composited with silverfish (NABE 1 (90:10); NABE 5C (70:30); NABE 5C (100:0); NABE 1 (70:30); NABE 1 (80:20), respectively) increased the iron, calcium, zinc, magnesium and folic acid content from 41 to 336 mg/kg, 447 to 15214 mg/kg, 36 to 276 mg/kg, 875 to 1113 mg/kg, and 7.75 to 47.47 mg/kg, respectively compared to the non-fortified raw beans. The treatments reduced total phytate content from 17.36 mg/g in raw beans to 12.92 mg/g in the extruded product. The iron bio-fortified beans – silverfish composite instant sauce had low levels of total aflatoxin, aflatoxin B1 and aflatoxin B2, and undetectable levels of Salmonella spp., E. coli, and Staphylococcus aureus indicating that the product is safe for human consumption. Addition of silver fish to the beans enhanced the sensory acceptability of the instant sauce with the sample containing NABE 5C (80:20) being the most preferred overall (p>0.05). From the findings, it was shown that addition of silver fish increases the nutrient content of an iron bio-fortified beans – silverfish instant composite sauce. The addition of silver fish also increases iron and folic acid content of the product and could therefore, reduce cases of anaemia among pregnant mothers. It was recommended that consumption of about 50g per serving of the instant sauce (80:20) twice a day can complement the iron-folic acid (IFA) from the diet as well as IFA supplements given out at antenatal centres to meet the recommended daily allowances for these micronutrients in pregnant women of reproductive age.