Development of iron rich products from traditional leafy vegetables grown in Lindi, Tanzania

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Sokoine University of Agriculture


The current study was conducted to develop iron rich products for feeding children under five years of age. Three Traditional leafy vegetables (TLVs), Amaranth hybrids known as amaranthus leaves (AML), Manihort esculenta known as cassava leaves (CAL) and Ipomea batatas known as sweet potatoes leaves (SPL) grown in Ruangwa and Nachingwea Districts in Lindi Region were used. They were collected from both home gardens (HG) and low land (LL). TLVs samples from the two sources were analysed in triplicate using standard methods for physico chemical parameters (pH, moisture content, dry matter content) and nutrient content for selected minerals and vitamins i.e. (iron, zinc, beta carotene and ascorbic acid) as well as microbial quality of the dried TLVs and vegetable powder formulations. The three TLVs which had been optimized for iron content, were used to prepare 4 vegetable powder formulations (F1–60.0:7.5:22.5); (F2– 70.0:5.0:15.0); (F3–80.0:2.5:7.5) and (F4–40.0:10.0:40.0). Spices were added to the vegetable powder formulations for flavour. The developed vegetable soup formulations were analysed for sensory quality as well as acceptability. Data was analyzed by R – statistical package (R version 4.0.3 2020). One-way analysis of Variance (ANOVA) was carried out to determine if there was any significance difference in micronutrients, physico-chemical among vegetables and across the sites. Means were separated by Tukey’s Honest at p<0.05. Significant differences in iron, zinc and beta- carotene content were found between vegetables at p<0.05. The solar dried TLVs, indicated that AML had the highest iron content, CAL had the highest zinc while SPL had the highest beta-carotene. Moreover, CAL and SPL had statistically significant higher (p<0.05) ascorbic acid than AML. In addition, zinc and ascorbic acid were highest in CAL whereas beta-carotene was highest in SPL for home grown vegetables. Highest iron content (p<0.05) was found from AML that had been grown under lowland grown vegetables. For microbiological parameters, significant differences (p<0.05) in Total plate count (TPC) were observed among the TLVs and between the two sites. The LL had the highest TPC than HG. Moreover, there was no significant difference (p<0.05) in TPC among vegetable powder formulations. No E. coli contamination observed among TLVs, neither from the two sites nor their formulations. Sensory evaluation for descriptive test revealed significant (p<0.05) differences in mean intensity scores between the vegetable soup samples. The descriptive attributes of the vegetable soup samples showed that F1, F2 and F3 had significantly higher (p<0.05) mean intensity scores for colour, aroma, and mouth feel than F4. The acceptability test however showed that all vegetable soup samples were accepted by panelists. F1 was the most liked due to colour, aroma and mouth feel followed by F2, F3 and finally F4. Furthermore, the preference mapping results showed that colour, aroma and mouth feel attributes were the main drivers for positive consumer preference for vegetable soup. Therefore, the development of TLVs soup powder formulations using a locally available processing technique is a promising solution to increase the uptake of iron to the under five children and other vulnerable members of the community. It also increases TLVs shelf life and availability throughout the year as well as an important contribution to income.


Masters Dissertation


Iron rich products, Traditional leafy vegetables, Amaranth hybrids, Sweet potatoes leaves