Ergonomic evaluation of manually-operated peanut butter mills

A JASSA evaluation of manually-operated peanut butter mills in Zimbabwe.Previous studies showed that the manually-operated peanut butter mills available on the market had technical problems related to the design and operation of the machines. One such problem was that the mills were too heavy for women to operate, resulting in limited operational time and ultimately, low total output. An ergonomic study of the original and modified versions of the mills was conducted at the University of Zimbabwe to verify the previously identified problems and develop appropriate and lighter mills for manual operation. A body discomfort assessment and heart rate measurement were used to determine stress endured by 12 women, as a result of operating the mills. Medium to high levels of discomfort were experienced in the lower back, neck, chest, lower arm, upper arm and shoulder. The heart rate readings showed that the mills currently available on the market were highly stressful (138 beats/minute), exceeding guidelines for safe manual operations. The modified mills, incorporating variable feed control devices, can be adjusted to ensure that stress levels are within recommended levels. The ergonomic study also established that for feed rates of 1.1 and . 1.5kg/hour, the mills produce peanut butter of acceptable fineness to the subjects, in one pass without over stressing the operator. In a separate field experiment using the same subjects, extremely high stress levels ( 150 beats/minute) were recorded with the traditional stone-mill

Tillage impact on soil erosion by water: Discrepancies due to climate and soil characteristics

No-tillage (NT) is promoted for soil and water conservation, but research findings on overland flow and soil erosion are inconsistent across different ecosystems, with some studies showing no benefits of NT over conventional tillage (CT). A global literature review was conducted to quantify the impact of NT on water runoff, sediment concentration and soil losses. The objective was to identify the underlying causes of the variability in the performance of NT across different environments. Data from 282 paired NT and CT runoff plots from 41 research studies worldwide were analysed using meta-analysis and principal component analysis (PCA). Sediment concentration and soil losses were 56 and 60% lower under NT than CT, respectively. These tended to be greater under CT than NT on long plots (90% for sediment concentration and 94% for soil losses) and steepest slopes (79 and 77%, respectively). Greater differences in sediment concentration and soil losses between NT and CT were observed in low clay soils and under temperate climates. While on average there were no differences on runoff coefficient, NT decreased runoff coefficient by about 40% compared to CT in mulched soils, under cool climate (5 years. Overall, the results indicated that NT has greater potential to reduce runoff and soil losses in temperate regions where soils of peri-glacial influence are relatively young, moderately weathered and fragile compared to the heavily weathered clayey tropical soils that are well aggregated and less erodible. The results of this study are expected to inform scientists, practitioners and policy makers on the links between land management and soil functioning processes. Policy makers and development implementers will be able to make informed choices of land management techniques for effective NT implementation, for instance by having more mulch input under warm climates

FABRICATION AND TESTING OF A BOX TYPE SOLAR COOKER

A model box solar cooker (BSC) was fabricated using locally available low cost materials. The BSC was compared with a renowned reflector solar cooker (CooKit) for thermal performance in heating water. The BSC and the CooKit constituted the experimental treatments in this study and each solar cooker type was replicated three times in a completely randomized design (CRD). The cookers were placed in a sunny spot away from buildings and trees to avoid shading. Six black plastic water bottles (800 ml) were filled with 700 ml of distilled water and placed in the centre of each cooker for energy generation monitoring. Each bottle had a hole drilled in the lid to accommodate an ordinary thermometer. The experiment was conducted on three selected days in January, February and March, 2014. Each trial run started at 10:00 hours and ended at 17:00 hours, with water temperature recorded every 10 minutes. The BSC recorded significantly (P < 0.05) higher peak water temperatures of 87C in January and 85.67C in February and these corresponded to mean energy gains of 0.17 MJ and 0.12 MJ, respectively, compared to 79.3C and 53.87C peak water temperatures (corresponding to 0.12 and 0.11MJ) recorded in the CooKit in the same months.. However, the mean cumulative energy generated by the CooKit (0.16 MJ) in March was significantly (P < 0.05) higher than 0.11 MJ gained in the BSC. These preliminary results have shown that the locally fabricated BSC has potential to provide adequate energy for pasteurising and possibly cooking various food products. Being a design based on local materials, it offers advantages of empowering local artisans and creating employment. It is recommended that further tests be conducted under varying weather conditions in order to identify points of possible design improvements before wide spread promotion

SMALL- AND MEDIUM-SCALE PRODUCTION AND MARKETING OF PROCESSED FRUITS AND VEGETABLES IN ZIMBABWE.

A study was conducted to investigate the constraints and prospects of small-scale production and marketing of processed fruits and vegetables in the eastern districts of Zimbabwe. A sample of 26 small-scale horticultural producers/ processors was randomly selected during the land reform exercise involving in-depth interviews to gain insight of the requirements for small-scale enterprises to effectively produce and market processed fruits and vegetables. The results showed that small-scale food enterprises were mainly engaged in the production of dried fruits, vegetables, and fruit jams. The growers are encountering technical, financial, infrastructural, institutional, social and information gaps as constraints. It was revealed that fruit and vegetable production declined sharply during the land reform transitional period. Food processing was hindered by lack of training, high prices of basic ingredients, lack of appropriate processing equipment and shortages of packaging material. Processors generally lacked marketing information and processing skills. From this study, it may be concluded that availability of appropriate processing equipment, processing skills, packaging material, and marketing information could improve financial returns to small-scale horticultural processors. It may be recommended that small scale fruit and vegetables processors require further training in their business and that banks and allied companies are urged to avail financial services to them

Ergonomic evaluation of manually-operated peanut butter mills

No Abstract Available JASSA: Journal of Applied Science in Southern Africa Vol.8(2) 2002: 76-8