Physical and Chemical Composition of Storage-Ripened Papaya (Carica papaya L.) Fruits of Eastern Tanzania

The proximate composition (ash, titratable acidity, crude fat, crude fibre, moisture and sugars), soluble solids, ascorbic acid, polyphenol oxidase activity, macro-nutrients and heavy metal contents of storage-ripened papaya (Carica papaya L.) fruits from Mbezi, Dar es Salaam, Tanzania were determined. The determinations were repeated for early, middle and late-season papaya fruits. The fruits were always harvested at the mature green stage and allowed to ripen during room temperature storage. The results showed that papaya fruits had high moisture content (>85.5%), low acidity (<0.18% c.a.), low crude fat (0.10 g/100 g-edible portion), moderate crude fibre (1.45 g/100 g-edible portion), high ascorbic acid content (>84.5 mg/100 gfw), moderate total sugars (>13.0%) and soluble solids (>12.9%) content. Early-season fruits had the highest polyphenol oxidase (PPO) activity while late-season fruits had the lowest PPO activity. During storage-ripening the PPO activity in the papaya fruit decreased. Of the determined macro-nutrients (Ca, K, Mg, Na), potassium content (420 mg/100 g-fw) was the highest. Heavy metals content was very low in the papaya fruits. Variations in moisture content, reducing sugars, total sugars, soluble solids, titratable acidity, ascorbic acid content and PPO activity were observed during the season and during the ripening period.Tanz. J. Sci. Vol 35 2009, 47-5

Polyphenoloxidase and Perioxidase Activity During Open Air Ripening Storage of Pineapple (Ananas comosus L.), Mango (Mangifera indica) and Papaya (Carica papaya) Fruits Grown in Dar es Salaam, Tanzania

Polyphenoloxidase (PPO) and perioxidase (POD), the enzymes responsible for causing browning and change in texture and flavor of fruits and vegetables, were extracted and measured in harvested mature pineapple (Ananas comosus L.), mango (Mangifera indica) (Viringe and Dodo varieties) and papaya (Carica papaya) fruits during off vine, open air, room temperature ripening storage. The initial (at harvest) average PPO activity values in Δ Optical Density (OD) per minute per cm3 of enzyme solution were 0.00074, 0.00083 and 0.0010 for early, mid and late season pineapple fruits respectively. The initial average PPO activity values in ΔOD/min/ cm3 of enzyme solution were 0.00152, 0.00121 and 0.0010 for early, mid and late season ‘Viringe’ mango fruits, respectively and 0.0054, 0.0041 and 0.0024 for early, mid and late season ‘Dodo’ mangoes. For papaya fruits, early, mid and late season fruits had initial average PPO activities of 0.00252, 0.00143 and 0.00085 Δ OD/min/cm3, respectively. The PPO activity decreased continuously during the open air ripening storage of all the fruits while the POD activity increased during ripening storage. Variations in PPO and POD enzyme activity were observed across the season and during the ripening period.Key words: Polyphenoloxidase, perioxidase, mango, papaya, pineappl

Lead pollution in urban roadside environments of Dar es Salaam city

Lead is among the most toxic elements in nature. It is non-biodegradable and its toxicity does not change with time. Use of leaded gasoline in motor vehicles is known as the major source of lead pollution in cities in the world. Dar es Salaam, the main city of Tanzania, has thousands of cars traveling along its roads. The lead contaminating urban roadside environments of Dar es Salaam was determined. Soil and vegetation samples were collected at various distances from the road edges of the New Bagamoyo, Sam Nujoma and Mandela roads in Dar es Salaam and analyzed for lead using Atomic Absorption Spectrophotometric methods. The results show that the soils and grasses along these major highways of Dar es Salaam were contaminated with lead. The highest lead contents (152.5 ppm in soil and 35.7 ppm in couch grass) were found in soils and vegetation within 1 to 5 meters from the road edge. The background lead levels measured at 150 meters from the road side were less than 1.2 ppm in both soil and vegetation. The lead levels along these roads exhibited strong correlation with the average traffic density (r = 0.912 for soil and r = 0.88 for grass). The levels of lead decreased exponentially with increasing distance away from the road. This suggests the major source of lead contamination of these areas was emissions from automobile traffic on these highways. The high levels of lead at 0 – 10 m from the roadside edge also suggest that soil and vegetation close to the roadside were a potential health hazard to both humans and animals. Tanzania Journal of Science Vol. 32 (2) 2006: pp. 61-6

Physico-Chemical Characteristics of Storage-Ripened Mango (Mangifera indica L.) Fruits Varieties of Eastern Tanzania

Two mango (Mangifera indica L.) fruit varieties, Dodo and Viringe, from two localities of Eastern Tanzania, (Muheza in Tanga and Ifakara in Morogoro), were harvested as mature green fruits during early, mid and late season and allowed to ripen while stored at room temperature. The fruits were analyzed for their proximate composition (ash, titratable acidity, crude fat, crude fibre, moisture), reducing and total sugars content, ascorbic acid and total soluble solids content, concentration of four macro elements (Ca, Mg, K, Na) and seven heavy metals (Al, Cd, Cu, Fe, Mn, Pb, Zn). The results showed that the mango fruits had high moisture content (>65%), moderate acidity (0.20 - 1.30% c.a.), low crude fat content (0.20 g/100 g-fw), low crude fibre content (0.85 g/100 g-fw), low ash content of 0.55 g/100 g-fw, high reducing sugars amounts (10.5 – 21.3%), high total sugars content (10.5 – 21.3%), high soluble solids content (14.2 – 26.5%) and high ascorbic acid content (15.8-25.1%). Potassium was the major macro element present (209.5 mg/100 g-fw). Heavy metal concentrations in the fruits were very low indicating insignificant pollution of the fruits. Moisture, reducing sugars, total sugars, and soluble solids content in the mango fruits increased within the season and with ripening storage. The ascorbic acid and titratable acidity content increased as the season progressed but decreased during the storage ripening period. Minimal seasonal changes were observed for ash, crude fat and crude fibre contents of the fruits.Tanz. J. Sci. Vol 35, 2009, 57-6

Urban Dietary Heavy Metal Intake from Protein Foods and Vegetables in Dar Es Salaam

Contamination of food and food products by heavy metals has made dietary intake as one of the major routes of these harmful elements to human beings. The human dietary intake of heavy metals cadmium, copper, lead and zinc from protein-foods (beans, meat, fish, milk) and green vegetables consumed daily from restaurants and street food-vendor kiosks in Dar es Salaam were determined using the Total Diet Study (TDS) method. The cooked food was bought from the restaurants and street food-vendors at several city locations (i.e. Buguruni, Manzese, Mwenge, Temeke and Ubungo) over several months and analyzed. Heavy metal concentrations were determined by Atomic Absorption Spectrophotometry (AAS) after wet digestion of the edible portions of pooled samples of the foodstuff. The results showed significant variation in heavy metal concentration among the foodstuff and at the different locations. The results were compared to the FAO/WHO levels for Acceptable Daily Intake (ADI) and Provisional Tolerable Weekly Intake (PTWI) to estimate risk of toxicity and to the US Recommended Dietary Allowance (RDA) and/or Estimated Safe and Adequate Daily Dietary Intake (ESADDI) for a deficiency in intake. The average weekly dietary intake of cadmium and lead from protein-foods and vegetables ranged from 0.20 - 0.42 µg/kg-bw/week (i.e. 2.82 - 6.00% of PTWI) and 4.77 - 9.83 µg/kg-bw/week (i.e. 68.1 – 140.4% of PTWI) respectively. These dietary intakes were below the ADI values of 0.5 µg/kg-bw/day and 3.6 µg/kg-bw/day of the WHO for cadmium and lead respectively. The daily dietary intake of zinc and copper at all the locations were also below the ADI for these elements, the average being 21.5% for copper and 19.8% for zinc. The results show clearly that the daily urban dietary intake of copper and zinc, from protein foods and vegetables along main streets at the above locations, was acceptable.Keywords: Heavy metal, dietary intake, protein foods, vegetables, Dar es SalaamTanz. J. Sci. Vol 36 2010, 85-9

Heavy metals in green vegetables and soils from vegetable gardens in Dar es Salaam, Tanzania.

Edible portions of five varieties of green vegetables, namely amaranth, chinese cabbage, cowpea leaves, leafy cabbage and pumpkin leaves, collected from several areas in Dar es Salaam, were analyzed for lead, cadmium, chromium, zinc, nickel and copper. Except for zinc, the levels of heavy metals in the vegetables grown at Tabata area were much higher than in the vegetables from Ukonga and Kiwalani. Amaranth and pumpkin leaves had more than 60% higher content of heavy metals, especially copper, chromium and lead, than the other vegetables. All vegetables from Tabata, Buguruni and Sinza had lead-levels higher then the FAO/WHO recommended permissible levels in foods. Amaranth, leafy and chinese cabbages had high zinc content. Zinc levels in chinese cabbage and leafy cabbage from Kiwalani, Sinza and Ukonga areas were higher than the permissible FAO levels in foods. The soils from Tabata and Sinza areas had high levels of lead, chromium, zinc and copper while the soils from Kiwalani, Makongo and Ukonga areas had high levels of zinc and copper. There was a direct positive correlation between the zinc and lead levels in soils with the levels in vegetables. Such relation was absent for the other heavy metals. Considering an average daily intake of only 202g of fresh vegetables per person per day, all the vegetables grown at Tabata and Buguruni had lead concentration which would be a health hazard for human consumption. Tanzania Journal of Science Volume 27 (2001), pp. 37-4

Speciation of cadmium, copper, lead and zinc in the waters of River Mzimbazi Dar es Salaam, Tanzania

The water of river Mzimbazi and its attributaries are known to contain heavy metals originating from industry and the water is used for domestic and vegetable irrigation purposes. The present study describes chemical forms of some of the heavy metals found in the water. Water samples from different locations along river Msimbazi were analysed by Differential Pulse Anodic Stripping Voltammetry (DPSAV) based on an operational scheme for the determination of the chemical forms of dissolved copper, lead, cadmium and zinc. Zinc (82%), cadmium (73%) and copper (93%) were found to exist mainly as soluble metal ions while lead existed as moderately soluble ions

Physicochemical characteristics of some locally manufactured edible vegetable oils marketed in Dar es Salaam.

The physicochemical properties (refractive index, saponification value, Free Fatty Acid (FFA) value, iodine value, acid value, peroxide value and tocopherol content) of seven edible vegetable oils manufactured in Tanzania, were assessed using standard procedures of the Association of Official Analytical Chemists (AOAC). Also determined were the levels of these properties with respect to shelf storage of the products. When compared with standard values recommended by the Codex Alimentarius Commission of FAO/WHO and with other published results, the locally produced vegetable oils were found to be of fair quality but of poor storage stability. Tanzania Journal of Science Volume 27 (2001), pp. 49-5

Anterior cruciate ligament resection and medial meniscectomy result in multifocal cartilage degenerations

Abstract: Damage to the meniscus and the anterior cruciate ligament alters the pattern of loading in the knee joint and frequently leads to cartilage degeneration and osteoarthritis. This study aimed to evaluate the area of greatest impact after traumatic osteoarthritic induction at the knee joint in sheep model. Osteoarthritis was induced unilaterally at the right hind knee of six sheep by surgical resection of the anterior cruciate ligament and medial meniscus. After 3 weeks recovery period, sheep were exercised once daily by running a 100 meters distance on a hard surface for 3 weeks. Gross and histological assessments were done. Six regions examined were; the patella, patella femoral groove, medial femoral condyle, lateral femoral condyle, medial tibia plateau and lateral tibia plateau. Their mean International Cartilage Repair Society grading was: 2.5±0.42, 3.3±0.17, 2.25±0.38, 1.33±0.25, 2±0.37 and 1.5±0.22 respectively. The control from all samples scored zero at the above regions. The lesions at various regions were significantly higher compared to the control (p < 0.05). Patella femoral groove was significantly higher compare to all other regions except for Patella. Lateral femoral condyle was the least (p < 0.05). Histological staining revealed defined osteoarthritic changes. Total excision of medial meniscus and anterior cruciate ligament followed by exercise regime induced osteoarthritis in the affected knee joint. The changes in pattern of degeneration, affected patella femoral groove the most; followed by the patella and medial femoral condyle, then medial tibia plateau, lateral tibia plateau and lastly the lateral femoral condyle