By Musanase, Solange
Weaning foods which are foods introduced to the infant after six months of age need to be rich in
energy and nutrients in order to complement breast milk. Therefore, this study was carried out
with the aim of producing extruded weaning food products from maize and sorghum composite
flour fortified with iron biofortified bean flour. Iron biofortified beans, common beans maize
(QPM) and sorghum were processed into flours by cleaning, drying, milling and sieving and
designated as Iron Biofortified Bean flour (FBF), Quality Protein Maize flour (QPMF), Sorghum
flour (SF) and Common Bean flour (CBF). The chemical compositions, functional properties and
antinutrient concentrations of the flours were analysed. The material balance method was used
for proportions of flours for mixing with 20 % protein and 60 % carbohydrate as the targets.
QPMF and SF were blended with FBF in the ratios of 23.83:53.18:22.99 and CBF in the ratio of
20.49:58.62:20.89 to produce extruded weaning food A and B, respectively. The extrudates were
evaluated for physicochemical, sensory and microbial quality characteristics. These were
compared with the characteristics of a commercial weaning food (C) analysed alongside. The
results showed that moisture contents of the cereal and legume flours were generally low (9.00 to
9.90 %) and (8.05 to 8.28 %), respectively. The ash contents (3.05 to 3.70 %) were higher in
legumes compared to cereal flours (1.60 to 3.00 %). Protein contents were significantly (p <
0.05) higher in the legume flours (31.51 to 32.68 %) compared to cereal flours (10.40 to 18.99
%). The carbohydrate (59.21 to 71.00 %) and energy (353.30 to 376.90 Kcal/100g) contents
were high in all the samples but the cereals contained more carbohydrate and energy than legume
flours. The vitamin E contents were similar in all samples (1.30 to 1.53 mg/100g) but the legume
flours had higher vitamin C (9.51 to 11.41 mg/100g), B1 (0.65 to 0.71 mg/100g) and B2 (0.19 to
0.21 mg/100g) compared to the cereal samples with FBF having the highest vitamin C (11.41
XVII
mg/100g), B1 (0.71 mg/100g) and B2 (0.21 mg/100g) but lower vitamin A (0.71 mg/100g). FBF
had high iron, zinc, iodine and phosphorus (14.23, 3.27, 2.07 and 487.67 mg/100g), respectively
compared to QPM (3.25, 1.53, 0.89 and 204.00 mg/100g), sorghum (5.34, 1.56, 0.90 and 344.00
mg/100g) and CBF (11.74, 1.82, 1.51 and 485.67 mg/100g). Functional properties of all flour
samples showed significant (p < 0.05) differences. Antinutritional factors were low in all flours.
The ash, protein and fibre contents (2.60 to 2.90, 18.95 to 18.97 and 3.18 to 3.65 %, respectively)
of samples A and B were higher than sample C (2.20, 15.38 and 1.14 %, respectively). Fat
contents were similar for all weaning foods (4.30 to 4.45 %) but carbohydrates and energy
contents (59.60 to 59.95 %), (354.11 to 354.39 Kcal/100g) of sample A and B were lower than
those of sample C (73.37 % and 393.78 Kcal/100g, respectively). The protein and carbohydrate
contents of sample A and B were very close to the targeted 20 % and 60 %. Vitamin contents of
samples A and B were lower compared to sample C. Incorporation of iron biofortified beans
resulted to improved levels of iron, zinc and iodine (7.83, 2.96 and 2.26 mg/100g), respectively
for sample A followed by sample C which had high amounts of calcium and phosphorus (548.00
and 367.77 mg/100g), respectively due to fortification. Extrusion cooking reduced antinutritional
factors by 98 %. The functional properties of sample A and B showed significant (p < 0.05)
differences to sample C. Microbial load was very low for all weaning foods. Bacterial count (1.5
x 10 to 1.0 x 10 cfu/g) and mould count (10 x 10 to 20 x 10 cfu/g), coliform count was no
detected. Sensory results showed that although extruded products (sample A and B) were
acceptable, but were less preferred (p < 0.05) to the commercial weaning diet (C).