Browsing by Author "Laswai, H.S."

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Adaption of the traditional coffee pulping machine to soybean dehulling
(2008-06) Silayo, V.C.K.; Laswai, H.S.; Ballegu, W.R.W; Mpagalile, J.J.; Kulwa, K.; Yuda, B.
Processing of soybean for human consumption requires wet heat treatment of the beans in order to inactivate anti-nutritional factors. After hot water treatment or steaming, dehulling of the bean has always been an uphill task for household processors in Tanzania. Dehulling is done by hand rubbing, which is tedious and time consuming. The traditional coffee pulping machine was adapted to dehull boiled soybean. Seven soybean varieties namely TGX-1876-2E, Bossier, Kaleya, TGX 1805-8E, Sable, Songea and Duicker were tried. This was a development process whereby three consecutively improved versions of dehulling machines were tested. The machines were branded Ml, M2 and M3, implying first, second and third generation, respectively. Bean recovery as a measure of performance was 74.3, 77.4 and 91.8% for Ml, M2 and M3, respectively compared with 89.7% for manual dehullingfrubbing. The respective throughput was 8, 10 and 28.2 kg/h compared with 0.43 kg/h for manual dehulling. The mean dehulling efficiency of the M3 dehuller was 82.4% which was the highest. The M3 dehuller's best performance was due to use of ball bearings to support the rasping roller axle instead of sleeves and its ergonomically suitable height. The M3 dehuller could be adopted for soybean dehulling under rural livelihood conditions but the economics for owning and running it needs to be explored. Its improvement to make it moiorised is recommended to increase throughput and increase chances for adoption in medium scale soybean processing.
Cassava Sun Drying Performance on Various Surfaces and Drying Bed Depths
(2013) Silayo, V.C.K; Lazaro, E.L.; Yustas, Y.; Laswai, H.S.
Processing of cassava (Manihot esculenta Crantz) to obtain flour is faced with a lot of technical constraints including inefficient drying. The traditional sun drying method is very inefficient as the product can take 2- 3 days to dry. Mould growth and other problems such as contamination of the product are likely and therefore necessitate intervention. Among the interventions was sun drying on a platform raised 1 m above ground in comparison with drying in a direct box solar dryer; by using trays with various bottom surfaces. The experiments were done using kiroba cassava variety obtained from the University farm, which was peeled and sliced into thin chips (2-3 mm) then sun dried on wire mesh, black polythene, white polythene and woven mat for three days. The material was dried for 8 hours daily after which it was kept indoors overnight. The surface with highest sun drying performance was wire mesh while white polythene was the least. The 10 mm bed depth attained constant weight in just about six hours of drying while for 20 and 30 mm bed depth it was about 16 hours and 40 mm bed depth for about 24 hours. There was moisture adsorption which was at 10, 22 and 28 hours for the 10 mm bed depth, 10, 20, 26 and 28 hours for 20 and 30 mm bed depths, and 28 hours for the 40 mm bed depth. The time 0,10 and 20 hours marked the beginning of drying whereas 8, 18 and 28 hours marked the end of drying. The best performance was therefore obtained on wire mesh and 10 mm bed depth and recommended for sun drying of cassava. However; there is need to investigate on whether there is significant quality difference between cassava sun dried at different bed depths investigated in this study
Cassava sun drying performance onvarious surfaces and drying bed depths
(2013) Silayo, V.C.K; Lazaro, E.L.; Yustas, Y.; Laswai, H.S.
Processing of cassava (Manihot esculenta Crantz) to obtain flour is faced with a lot of technical constraints including inefficient drying. The traditional sun drying method is very inefficient as the product can take 2- 3 days to dry. Mould growth and other problems such as contamination of the product are likely and therefore necessitate intervention. Among the interventions was sun drying on a platform raised 1 m above ground in comparison with drying in a direct box solar dryer; by using trays with various bottom surfaces. The experiments were done using kiroba cassava variety obtained from the University farm, which was peeled and sliced into thin chips (2-3 mm) then sun dried on wire mesh, black polythene, white polythene and woven mat for three days. The material was dried for 8 hours daily after which it was kept indoors overnight. The surface with highest sun drying performance was wire mesh while white polythene was the least. The 10 mm bed depth attained constant weight in just about six hours of drying while for 20 and 30 mm bed depth it was about 16 hours and 40 mm bed depth for about 24 hours. There was moisture adsorption which was at 10, 22 and 28 hours for the 10 mm bed depth, 10, 20, 26 and 28 hours for 20 and 30 mm bed depths, and 28 hours for the 40 mm bed depth. The time 0,10 and 20 hours marked the beginning of drying whereas 8, 18 and 28 hours marked the end of drying. The best performance was therefore obtained on wire mesh and 10 mm bed depth and recommended for sun drying of cassava. However; there is need to investigate on whether there is significant quality difference between cassava sun dried at different bed depths investigated in this study.
Improvement of cassava production, processing, marketing and utilization through introduction of disease-tolerant cassava varieties
(2008-06) Silayo, V.K.; Laswai, H.S.; Lazaret, E.L.; Mpagalile, J.J.; Ballegu, W.R.W.
A baseline survey was conducted in Tongwe, Kabuku, Chanika and Mikongeni villages, located in the Districts of Muheza, Handeni, Ilala and Kibaha, respectively, in the cassava growing ecosystem of Tunga, Coast and Oar es Salaam regions. The objective was to establish baseline data as entry point for improving production, utilization, processing and marketing of cassava in these areas. The survey involved 104 households, represented by 62.5% male and 37.5% female farmers, using a structured questionnaire. The results were coded and analijsed using the SPSS statistical package. It was observed that majority of households farmed on land size of less than 2 ha, with about 80.2% farming on their own land and 91.8% farming on rented land. Most farmers (54.7%) produced less than 1.25 MT of fresh cassava roots per hectare, with a few producing as far as 10 times more. The crop was slightly more of a cash crop than a food crop, with yearly mean production of 2.18 MT compared with 1.44 MT (53%) sold. Production faced limitations, especially lack of market (37.6%) and low disease tolerance (19.8%). The varieties grown were mainly Kiroba, Cheupe, Cheusi Mwangia and Mkunungu in Tongwe, Chanika, Mikongeni and Kabuku villages, respectively. Introducing new varieties as a solution to the reported problems is required but the essential attributes should be: high disease tolerance (28.5%); high yield (25.9%); sweetness when chewed (13.8%) and early maturity (10.5%), which are potential factors towards solving marketing problems. In a follow-up program, Kiroba variety, which is a relatively high disease tolerant variety, was introduced in Kahuku, Mikongeni in Chanika villages to farmer groups and individual farmers. While results in Mikongeni and Chanikn did not show remarkable changes Kabuku village registered very positive impacts, just after two years. These include the increase of the numbers of farmers groups from 1 to 3, individual farmers from 20 to 37, overall area planted from 2 to 4.6 hectares, yield from average of 1.25 to 18 MT per hectare and cash earned per hectare from almost zero to 800,000 shillillgs and average price of about 4,500 shillings per 100 kg of fresh cassava. Introducing disease-tolemni cassava oarieties could change the stnius of this crop and contribute to iiuprooed lioelihood. For sustainability of tilt' processing iiidustri], pricing of raw nuuerinls should not exceed that for the [resli market during high price seasons.
Improving sweet potato processing and storage performance throug slicing, drying and packaging
(2003) Silayo, V.C.K.; Laswai, H.S.; Makungu, P.J.
Sweet potato is an important food security crop in, many parts of Tanzania. Despite this potential, research into its post-harvest handling for maximum utilisation hass been low. The objective of this study was therefore, to assess slicing performance of a fabricated hand operated slicing machine against the traditional knife slicing by hand in the production of michemhe. It also assessed how slice thickness, the drying surfaces, and packaging of the slices influenced quality during storage. The slicing machine was set to produce slices of 4.8 12 and 16 mm thickness. Together with the traditionally obtained slices the samples were dried on three surfaces (perforated surface, thatched roof and on the ground) for three days. Dry samples were then packaged in polypropylene bags, perforated polyethylene bags and sealed plastic containers and stored for nine months with observation carried in three months intervals. The investigations included moisture content, fungal count and mycotoxin detection discoloration and insect infestation aa quality attributes. Results showed that the slicer throughput ranged between 16 and 46 kg/h of fresh peeled roots in the thickness range of 4-16 mm, against 17 kg/h for traditionally sliced (75 mm) sweet potatoes. During drying, weight of slices decreased exponentially with time. In terms of drying effectiveness, the three drying surfaces used displayed almost the same final mean moisture content in the lower slice thickness range (4-8 mm). With increased slice thickness to 12 and 16 mm: the perforated surface was the most effective (10. 63-18. 03%) followed by the ground floor- (15.67-18.65%) and thatched roof the least (16.5-19.36%) Quality of dried michembe decreased with storage time and the best performance was obtained in polypropylene bags for the nine months storage. Packaging in sealed plastic containers produced the worst results. Quality was also influenced by the drying surfaces used with ground floor resulting in poor product and perforated surface the best. Increasing the slice thickness affected the quality of the dry product except in the range of 4 to 8 mm. Slicing of the roots to 4-8 mm drying on perforated surface and packging in polypropylene bags for room temperature storage of up to six months produced michembe of acceptaple quality. Use of improved slicing machines including mechanically powered machines requires further investigation. Studies on more drying surfaces more packaging materials, and nutrition of michembe are also recommended