The influence of the combined microwave power and hot air ventilation on the drying kinetics and colour quality of tomato slices

Tomato is one of the most important fruit used as an ingredient in different foods in food processing and preparation. Fresh tomato consists of about 91% of moisture. Tomato has to pass through all three rates of drying (constant, first and second falling rate period) during drying, using hot air ventilation, and requires prolonged time with much of quality changes. In this study, microwave assisted hot air ventilation drying of tomato slices had been considered. Microwave oven working at 2450 MHz, using different power densities (1, 2 and 3 W g-1) was combined with hot air ventilation at 50°C and hot air ventilation drying without microwave power at 40, 50, 70 and 80°C to dry tomato slices down to 10% moisture content. The drying characteristic curve was analyzed to determine the drying time. The tomato slice sample dried faster when subjected to microwave heating, coupled with hot air ventilation at 50°C. The drying times required for tomato slices to reach 10% moisture content were found to be 3.2, 2.5 and 1.3 h, using 1, 2 and 3 W g-1 microwave power densities, coupled with 50°C hot air ventilation, respectively. On the other hand, the drying time of tomato slices to 10% moisture content required 20.5, 13.1, 9.6, 6.8 h for drying at 40, 50, 70 and 80°C, using hot air ventilation without supplementing heating with microwave power. Microwave drying maintained the superior colour of tomato slices after drying period, compared to the other treatments.Key words: Microwave, tomato slice, drying equation, colour, drying rate, moisture content

Evaluation of a seed storage facility in relation to preserving seed moisture, vigour and germination

The performance of a solar energy-assisted seed storage room was evaluated through an ordinary 22-m3 room that was retrofitted with a solar  collector, inlets and chimney. The structure was made of a solar collector to heat the ambient air before entering the chimney. The chimney  circulated the air inside the structure and inlets. To compare the performance of the modified storage room, a room with a similar capacity and  without the retrofitted components (control storage room) was used. Twelve 8 kg bags of maize were stored in each storage room for a period of  three months. Samples were taken every two weeks to determine germination rate, moisture content and seed vigour. The temperature and relative  humidity (RH) was measured during storage. The RH in the control storage was significantly higher (P≤0.05) (60.6 ± 5.87%) than in the  modified storage (40.1 ± 3.21%) during the day. However, at night, the RH in the control storage room was significantly lower (P≤0.05) (58.5 ± 7.32%)  than in the modified storage (63.7 ± 6.28%). The RH in the modified storage room increased from 40.1% during the day to 63.7% at night. The RH in  the control storage room decreased slightly from 60.6% to 58.5% during the day and night. The seed moisture content in the modified storage  facility was significantly lower (P≤0.05) (12.6 ± 0.21%) than in the control storage room (13.3 ± 0.52%). The moisture content in the modified storage  room decreased from 12.6% to 12.4%, whereas in the control room, moisture content increased from 12.6% to 13.8% in three months. The seed  germination rate obtained after three months of storage in the modified storage room was significantly higher (P≤0.05) (98.5 ± 0.85%) than in the  control storage room (96.8 ± 1.49%).The seed igour obtained in the modified storage room was significantly higher (93.6 ± 0.35%) than in the control  room (91.7 ± 2.08%) (P≤0.05). Seed stored in the control storage lost vigour at a faster rate, compared to the seeds stored in the modified storage room. Therefore, the modified naturally-ventilated seed storage room maintained seed quality better than the control storage room

A review on the integrated agro-technology of papaya fruit

The aim of this review was first to explore the effect of different pre-harvest factors affecting the quality of papaya including genetic factors, climatic conditions, cultural practices on post-harvest quality of the papaya fruit. Post-harvest physiology of papaya in terms of its respiration, ethylene production and sensitivity and transpiration was reviewed. Post-harvest handling and factors affecting quality of papaya were also examined. Post-harvest biochemistry of papaya including enzyme activity, carbohydrates, organic acids, pigments and volatiles in papaya fruit were assessed. A review on post-harvest handling of papaya fruit including packaging and storage environments (temperature and relative humidity) were presented. On the other hand, the post-harvest microbiology of papaya was reviewed. Papaya supply chain is much limited to local destinations with quite few exceptions mainly due to lack of integrated post-harvest handling technologies. Pre- and post-harvest treatments were found to have a significant effect on post-harvest quality of papaya and the fruit storage stability under dry and hot climatic conditions of Africa. An integrated agro-technology research and development approach aimed at improved yield and quality at harvest as well as the maintenance of qualities of papaya fruit in order to encourage farmers to produce and for marketing of the papaya fruit under African local supply chain conditions and for export market is recommended.Key words: Papaya fruit, post-harvest, agro-technology, pre-harvest

Effect of varieties on physicochemical and pasting characteristics of water yam flours and starches

Water yam (Dioscorea alata) flour and starch of ten varieties were processed using standard wet-milling procedure prior to the determination of their physico-chemical and pasting properties. The swelling power of the samples was characterized in the category of high restricted-swelling starch (9.21 to 11.03% for flours; 9.49 to 13.80% for starches). This characteristic is desirable for the manufacture of value-added products such as noodles and composite blends with cereals. The pasting temperature (78.05 to 86.13°C, for flours; 80.38 to 86.15°C for starches) and time (4.44 to 5.17 min for flours; 4.53 to 5.17 min for starches) of test varieties indicate higher gelatinization temperature and longer cooking time. Results of analyses of physico-chemical and pasting properties indicated significant differences (P < 0.05) among the varieties. All the varieties studied gave the potentials for the manufacture of these value-added products and non-food applications of starch such as in paper and textile industries. Moreover, the results obtained in this study also show that potential exists for selecting nutritionally superior varieties of D. alata (TDa 297 and TDa 00/00194 for flour, TDa 297 and TDa 98/01183 for starch) and these varieties could be good sources of diets to its consumers and serve as food security in developing countries.Key words: Water yam, physico-chemical, pasting, flour, starch

Evaluating Open Data Innovation: A Measurement Model for Digital Innovation Contests

Digital innovation contests emerge as important intermediaries in open data markets. However the understanding of how contests affect innovation value chains is low and there is a lack of innovation measurement frameworks to support the management of digital innovation contests. Therefore, in this paper we apply design science to design a measurement model for digital innovation contests from the organizer’s perspective that adds to the available knowledge of innovation measurement. We use a recent case of digital innovation contests to motivate the model and discuss its implications on the innovation value chain. The measurement model contributes with new knowledge in the area of open data innovation and provides support for practice in managing innovation through digital innovation contests. For future research we intend to enhance the model to also measure the effects on innovation ecosystems, to operationalize the measures and to evaluate the model in several digital innovation contests as well as to include the perspective of the participants

Feeding your soil-nurturing the people

United States Agency for International Developmen

Natural resource management: Africa RISING science, innovations and technologies with scaling potential from the Ethiopian highlands

United States Agency for International Developmen

Decision support tools for fertilizer recommendation

United States Agency for International Developmen