Abstract:The physicochemical composition of harvested soursop (Annona muricata L.) fruits from Coast region,Tanzania, during open-air storage was determined. The ash, titratable acidity, crude fat, crude fiber, moisture and sugars content were determined by proximate analysis. Ascorbic acid contents were determined using the 2,6-dichlorophenol-indophenol dye method while macro-nutrients and heavy metals were determined by Flame Atomic Absorption Spectrophotometry (FAAS). The fruits were harvested at the mature ripe stage and kept in open air storage over several days. The determinations were done immediately after fruit arrival at the laboratory and thereafter at intervals of two days from the day of harvest. The results showed that soursop fruits had high moisture content (73.1% -82.1%), low titratable acidity (0.10 -1.25% ca), low crude fat (0.42 mg/100 g-fw), moderate ash content (0.87 mg/100 g-fw) and crude fibre content (6.09 mg/100 g-fw), high ascorbic acid content (34.0 -19.7 mg/100 g-fw), high total sugars content (34.3% -45.3%), reducing sugar content (18.9% -39.2%) and sucrose content (15.5% -30.0%). Of the macroelements Na, Ca and K, the average content were 895.6, 870.3 and 367.5 mg/100 g-fw respectively. Heavy metals (Fe, Zn, Cu, Pb and Cd) content was very low in the soursop fruits, ranging between <0.0015 mg/100 g-fw for Cd and 0.82 mg/100 g-fw for Fe. During storage, the moisture content, titratable acidity level and sugars content in the fruit were all increasing whereas the ascorbic acid content was decreasing. There were no significant changes during storage for levels of crude fat, fiber, ash, mineral elements and heavy metals. The findings from this study suggest that this fruit from coast region of Tanzania can contribute nutritionally to the health of the consumer.

Abstract:The concentrations of heavy metals of Cd, Cu, Cr, Pb and Zn were determined in cauliflower (Brassica oleracea L.var. butrytis L.), carrot root (Daucus carota L.), tomato fruit (Lycopersicon esculenta Mill.), onion bulb (Allium cepa L.) and leafy cabbage (Brassica oleracea var. capital capitata L.), and the respective soils from Morogoro region, Tanzania. The accumulated heavy metals were quantified and levels compared to FAO/WHO (2003) and TZS (2007) safety limits for such produce. The methodology involved random sampling, extraction of the metals from the tomatoes, vegetables and soil and determination of heavy metals by using ICP-OEC and GFAAS. The results showed that levels of Cd, Cu, Cr, Pb and Zn at 90% of the sites in vegetables and tomatoes were above the FAO/WHO limit. The mean concentrations of Cd, Cr, Pb and Zn in all vegetables and tomatoes except Cu were also found to be above this limit therefore advocating a health risk for consumers. Levels of heavy metals in the soils were below the limits of the Tanzanian standard (TZS 972: 2007) and were lower than levels found in vegetables. The bioconcentration factor for Cu recorded 1 for tomatoes and cabbage at Towelo and below 1 for tomatoes and cauliflowers from Mgeta. Cd in onions at Mgeta as well recorded below 1. However, the bioconcentration factor for these heavy metals in vegetables and tomatoes in all other sites were found to be above 1 in all heavy metals an indication of high uptake of heavy metals in the vegetables and tomatoes from the soil. These results suggest that such vegetables and tomatoes might place the consumers at health risk; therefore they are not safe for consumption in their raw state.