Browsing by Author "Wenaty, Alex"

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Effect of different processing methods on the anti-nutritive components of selected indigenous vegetables
(Asian Food Science Journal, 2024) Ngungulu, Theresia Ponsiano; Wenaty, Alex; Chove, Bernard; Suleiman, Rashid; Mbwana, Hadijah
Indigenous vegetables are widely utilized due to their high nutritional profiles, easy availability, and accessibility in rural areas. The consumption of indigenous vegetables is limited by their high perishability nature which causes high post-harvest losses. Also, the presence of anti-nutritive components which tend to affect the bioavailability of micronutrients, poses a challenge in availing their full nutritional potential to consumers. This study aimed to determine the effect of boiling, fermentation, solar and sun drying (with and without blanching) on the anti-nutritive components of the leaves of Cassava (Manhot esculenta Crantz), Black jack (Bidens pilosa) and Bitter lettuce (Launaea cornuta). The raw, dried, boiled and fermented vegetables were evaluated directly after being subjected to their corresponding treatments. Total oxalate and hydrogen cyanide (HCN) were analyzed using titrimetric methods and phytate was determined using the UV spectrophotometric method. From the results, oxalic acid ranged from 180.2 ± 1.56 to 26.3 ± 2.34mg/100g, phytate ranged from 18.8 ± 1.07 to 0.7 ± 1.11mg/100g and hydrogen cyanide ranged from 357.1 ± 10.56 to 4.1 ± 2.49mg /100g across the treatments. All processing methods significantly (P<0.05) reduced hydrogen cyanide and oxalic acid content in all vegetable samples. Phytate was significantly reduced (P<0.05) after boiling and fermentation while, all drying treatments resulted in non- significant changes in phytate content. In consequence, all processing methods studied proved to be effective in the reduction of hydrogen cyanide and oxalic acid. Boiling and fermentation showed their effectiveness in the reduction of phytate. Therefore, it is recommended that these plants should be eaten boiled or fermented to increase the bioavailability of micronutrients
Prevalence of organophosphate pesticide residues and the associated risks of dietary exposure through selected vegetables from Ilala district, Dar es Salaam, Tanzania
(Asian Food Science Journal, 2025-02-15) Tegekanya, Rosemary; Wenaty, Alex; Chove, Bernard; Mbwana, Hadijah
The increasing reliance on pesticide use in agricultural practices, particularly in developing regions such as Tanzania, poses significant risks to food safety and public health. This study investigated the prevalence and concentration of organophosphate-based pesticide residues in commonly consumed vegetables, specifically Amaranth (Amaranthus), Chinese cabbage (Brassica rapa Pekinensis) and Sweet potato leaves (Ipomoea Batatas) cultivated in Ilala district of Dar Es Salaam City. Data on vegetable consumption were collected from 138 vegetable farmers using the 24-hour dietary recall method. The analytical methodology employed gas chromatography coupled with mass spectrometry (GC-MS). Vegetable samples were prepared through a series of extraction and purification steps. The results revealed significant variation (P < 0.05) in organophosphate residue concentrations across the different vegetable types and sampling sites. The potential health risks associated with dietary exposure to these pesticide residues were evaluated by employing deterministic approaches. The average residual concentration of profenofos in chinese cabbage was found to be 0.044 ± 0.014mg/kg, while in amaranth exhibited a higher concentration of 0.182 ± 0.056mg/kg. Notably, the concentration of diazinon in amaranth reached 0.272 ± 0.156mg/kg, indicating a significant presence of this pesticide. From this study, chlorpyrifos and marathion emerged as the predominant pesticides, significantly surpassing Maximum Residue Limits (MRLs) established by international food safety standards. The Estimated dietary intake (EDI) for chlorpyrifos was determined to be 0.004mg/kg body weight per day, with an acceptable daily intake (ADI) of 0.01mg/kg body weight per day, the resulting hazard index (HI) values for chlorpyrifos in both chinese cabbage and amaranth was >1, indicating a significant risk of adverse health effects from chronic exposure. The findings underscore a critical public health concern as consumption of these vegetables may expose consumers to harmful pesticide levels, particularly vulnerable populations such as children and agricultural workers.
Textural, cooking quality and sensory acceptability of noodles incorporated with Moringa Leaf and sardine powders
(European Journal of Nutrition & Food Safety/ SSRN, 2023) Mpalanzi, Victoria Thobias; Chaula, Davis Naboth; Wenaty, Alex
Noodles with varying percentages of wheat flour, moringa leaf and Sardine powders were developed and tested for texture, cooking quality, and sensory qualities. Various formulations were used to make the noodle samples. Noodles with moringa leaf powder were developed using in the following wheat and Moringa proportions in percentage: 99.6:0.4 (WM1), 99.2:0.8 (WM2) and 99:1 (WM3). Noodle samples containing sardine powder were created in the following ratios: 95:5 (WS1), 90:10 (WS2), 85:15 (WS3), and 100:0 wheat flour. Textural qualities of the noodle samples were measured, including hardness, cohesiveness, springiness and adhesiveness. The inclusion of moringa leaf powder and sardine powder resulted in a considerable reduction in hardness and cohesiveness when compared to the wheat control. The noodles became softer and less cohesive as the concentration of moringa leaf powder or sardine powder increased. The noodle samples' cooking loss, volume increase and water absorption were also measured. Higher concentrations of moringa leaf powder or sardine powder resulted in greater cooking loss as well as lower volume and water absorption. This implies that the inclusion of these powders altered the texture and water-holding capacity of the noodles. Additionally, sensory evaluations were performed to determine the acceptability of the developed noodles in terms of color, aroma, texture, taste and overall acceptability. The results revealed that when the concentration of moringa leaf powder or sardine powder increased the sensory properties of the noodles samples were altered. Lower concentrations of these powders were related with greater acceptance scores in general. Specific characteristics of the noodles-, such as color, aroma, saltiness and hardness were evaluated using quantitative descriptive analysis. The results showed that adding moringa leaf powder and sardine powders altered these properties with larger concentrations causing more noticeable changes.