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 Title: Green soybeans: Physical and rheological properties, optimization of harvest time, and mechanical harvesting and shelling Author(s): Mbuvi, Stephen Wambua Doctoral Committee Chair(s): Litchfield, J. Bruce Department / Program: Agricultural and Biological Engineerin Discipline: Agricultural Engineering Degree Granting Institution: University of Illinois at Urbana-Champaign Degree: Ph.D. Genre: Dissertation Subject(s): Agriculture, Agronomy Engineering, Agricultural Abstract: Physical and rheological properties of green soybeans were measured at different stages of seed development. These properties included texture, color, size, and seed strength. Mathematical models were developed relating each property to seed development. The models were then combined to develop an objective function to predict the "value" of green soybeans as a function of seed development. The value was optimized by taking the first and the second derivatives of the objective function. The value of Hack variety was found to be optimized at about 1620$\sp\circ$C-days, about 90 days after planting.The above properties of green soybeans compared favorably with those of green peas and lima beans. In all the properties measured, soybeans were found to be between peas and lima beans; thus, green soybeans have a potential of being competitive as a vegetable.Time required to hand shell and seed damage caused by hand shelling green soybean pods were significantly reduced by blanching the pods. Blanching had no significant effect on the time of mechanical shelling, however seed damage caused by mechanical shelling was significantly reduced by blanching before shelling. Texture and color were also affected by blanching. Color factor, defined as $-$a/b, where a and b are Hunter color parameters, was higher, and texture, given by FTC shear press reading, was lower when pods were blanched for 1 minute than when they were not blanched at all. Blanching pods for up to 10 minutes, did not further change these properties significantly.Two shellers, which were modified to shell green soybean pods, were studied: the Taylor roller-type sheller and the Sinclair-Scott rotary drum sheller. The Taylor sheller performed well with 95% seed recovery from the pods and only 3.4% damage. However, the pods had to be fed by hand. For commercial application, this sheller needs an automatic feeding mechanism that can align the pods and feed them end to end between the rollers. The Sinclair-Scott drum performed reasonably well with 77% seed recovery and 7.2% damage. The model of this sheller tested may be feasible for commercial application.Finally an FMC pea combine was used for harvesting green soybeans. The shelling drum screen size used was 0.0159 m (5/8") which is normally used for large seeded peas. By adjusting drum and beater speeds as well as the cleaning fan speeds, it was possible to harvest clean shelled soybeans. Seed damage caused by the combine was 11%, and the cleaning fans caused an additional 5% seed losses. Overall, the pea combine performed very well, and it offers great potential for the harvesting of green soybeans. Issue Date: 1991 Type: Text Language: English URI: http://hdl.handle.net/2142/19347 Rights Information: Copyright 1991 Mbuvi, Stephen Wambua Date Available in IDEALS: 2011-05-07 Identifier in Online Catalog: AAI9210910 OCLC Identifier: (UMI)AAI9210910
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