Quality and Safety of Iron Biofortified Bean-Silverfish Composite Instant Flour for Making Sauce

Abstract

Beans are the main source of protein in the diet of many Ugandans, especially rural households, the urban poor, schools, and prisons. Beans are mainly utilized following drying with hardly any value addition and require long preparation times. This study evaluated the nutrition quality and safety of instant iron biofortified beans and silverfish composite flour using extrusion cooking. Three varieties of iron biofortified beans (NARO BEAN 1, 2, and 5C) were composited with ground fish in the ratios of 70:30, 80:20, and 90:10. The composite flour was analyzed for proximate composition, selected minerals, iron bioavailability, phytate content, folic acid content, and microbiological safety. The composite flour (50 g) was reconstituted into a gravy-type instant sauce with boiling water (100 mL) and subjected to sensory evaluation using a panel of 50 semitrained analysts. Addition of silverfish to the beans enhanced the sensory acceptability of the instant sauce with the sample containing the yellow bean variety NARO BEAN 5C (80:20) being the most preferred. Compositing beans with silverfish significantly increased moisture, protein, calcium, zinc, magnesium, and folic acid content. The combination yielded more bioavailable iron. The product had low levels (< 0.25 ppb) of aflatoxins, which is lower than the FDA's action level for aflatoxins in food/feed of 20–300 ppb and undetectable Salmonella spp., Escherichia coli, and Staphylococcus aureus indicating its safety.