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Title: The design and application of a small-scale corn degerming process for the recovery of transgenic products from corn seeds
Author: Cody, J. T.
Awarding Body: University of London
Current Institution: University College London (University of London)
Date of Award: 2004
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This thesis presents the issues involved in designing a small-scale com seed degerming process based on large-scale principals, its characterisation and optimisation using the method of statistical experimental design and analysis, and its application to the processing of different types of com seed. During the early stages of process development for the extraction and purification of recombinant proteins produced in genetically modified crops, scarce quantities of material limit the extent of process investigations at pilot-scale. The small-scale degerming process was therefore designed for the development of a process suitable for handling small quantities of transgenic com. This process consisted of a small-scale degerming device, followed by a separation process consisting of roller-milling and sieving, capable of processing 50 seeds (approximately 12g). Successful degerming of transgenic com seed separated oil-and protein-rich germ (waste stream) from the product-containing endosperm fraction (product stream) of the seed. Oil content and mass of the product and waste streams were used to assess and compare degerming quality between all seed types. The degermer and separation process design were based on the principal operating factors identified in the large-scale operations used in com dry milling. Both operating factors and material properties affected the quality of degerming. The factors which had the largest impact on degerming were the degermer disk clearance, roller-milling and seed moisture content. Maximum degerming and separation, consisting of product stream containing 32.5% seed oil in 90.2% seed mass, occurred at a seed moisture content of 21%, (w/w), a disc clearance of 9mm, and three stages of roller-milling. Variation in quality between seed types was shown to affect degerming quality when operating the degermer under constant conditions. Five different types of seed were processed through the small-scale degermer. Two were transgenic, and three were non-transgenic, and one of these was additionally processed through a pilot-scale Beall degermer. The small-scale com degerming process was shown to separate seed fractions from all varieties of seeds processed. The greatest difference in quality of small-scale degerming between these different seed types was between the 'high quality' non-transgenic hybrid and either of the two transgenic seed types. Better degerming was achieved using the high-quality seed hybrid (detailed above) than the transgenic seed (84.2% seed mass, 46.8% seed oil) when processed using the optimised operating conditions. The quality of degerming that could be achieved using the pilot-scale Beall and small-scale degermers was compared using the 'low quality' non-transgenic seeds, which were physically the most similar to the transgenic seeds. The small-scale degerming process was shown to separate a greater proportion of germ from the endosperm, represented by the high mass of lower oil content product stream (81.5% seed mass, 29.3% seed oil) than that seed which had been degermed using the pilot-scale Beall degermer (92.5% seed mass, 64.3% seed oil).
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available