Some mounted ill. Bibliography: leaves 80-85.

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The effect of heat treatment on the protein quality and the metabolizable energy value of rapeseed meal was investigated. Different rapeseed meal samples were autoclaved at 121° c for different times. a significant reduction (p < 0.05) in the in vitro protein digestibility resulted from the autoclaving treatment. Further reduction in protein digestibility occurred when samples were autoclaved with glucose. Poor growth and feed efficiency in the chicks were observed due to feeding of autoclaved rapeseed meal ration. Lysine supplementation of autoclaved and unautoclaved rapeseed meal improved growth and feed efficiency. Maximum growth on the control ration was obtained with 0.16% lysine supplementation whereas 0.24% maximized the growth of chicks on autoclaved rapeseed meal. No significant effect was observed on liver weight expressed as percentage of body weight, however, pancreas weight was significantly greater (p < 0.05) in birds receiving autoclaved rapeseed meal than the controls. There was no significant difference in metabolizable energy value of autoclaved and unautoclaved rapeseed meals. / Land and Food Systems, Faculty of / Graduate

Rapeseed is grown from two closely related species of Brassica in many varieties. The behaviour of seven insects was studied to determine their responses to low erucic acid rapeseed, represented by a typical and a Canola variety of each species. The Canola varieties have a lower gluco-sinolate concentration in the seed coat than typical varieties. The insects were chosen because they were oligophagous or polyphagous. The actions of adults of two species of moths, Mamestra configurata Walker and Plutella maculipennis (Curtis), were studied by using an olfactometer; four species of aphids, Myzus persicae Sulzer, Macrosiphum euphorbiae (Ashmead), Brevicoryne brassicae (Linnaeus), and Acrythosiphon pisum (Harris), were studied when the adults were placed at the base of each type of plant. The insects responded in accordance with their normal associations with cruciferous plants as hosts. Their responses were not materially affected by genetic differences among the four varieties, even though these included distinct morphological and biochemical differences. Behavioural differences towards plant species were observed in the polyphagous aphids, which affected their distribution on the plants. These differences were not associated with varieties or glucosinolate contents. These results indicated that the differences between the two rapeseed species and typical and Canola varieties would neither materially affect the responses of attacking insects nor the resistance of the plants to insect attack in the field. / Land and Food Systems, Faculty of / Graduate

Rapeseed protein isolate from pH 10 NaOH extraction was analyzed by gas chromatography (isothiocyanates) and UV absorption (goitrin) (Youngs and Wetter, 1967) and found to contain glucosinolates at levels equivalent to 0.75 mg 3-butenyl isothiocyanate, 0.57 mg 4-pentenyl isothiocyanate, and 0.51 mg oxazolidinethione (goitrin) per g isolate. A two-stage process was developed to decrease the levels of these toxins. Isolate slurry was incubated at pH 7.2 with crude myrosinase extracted from white mustard seed (to convert glucosinolates to isothiocyanates and goitrin), adjusted to pH 10, and passed through a granular activated carbon column. Subsequent analysis revealed only 0.006 mg 4- pentenyl isothiocyanate per g isolate. Goitrin was not detectable. Infrared analysis confirmed that the column was also partially effective in nitrile removal. To eliminate the need for myrosinase purification, the process was modified to include ground white mustard seed addition directly to rapeseed meal slurry. After incubation, the protein was extracted, purified by isoelectric precipitation, re-dissolved, and treated by the activated carbon column. This modification was included in the "recommended detoxification procedure". Subsequent experiments on protein extracts prepared and carbon treated at pH's from 3 to 12, inclusive, revealed that all treatments in the range of pH 3 to 10 were at least 93% effective in isothiocyanate removal. A lower efficiency was observed above pH 10. Storage tests (24 hours) on aglycone containing protein solutions showed increased loss of isothiocyanates with increasing pH from 5 to 10. This could be due to their interaction with protein (Bjorkman, 1973). The column completely removed chromatographically purified glucosinolates from aqueous solution. However, the results could not be duplicated for solutions containing rapeseed protein. Glucosinolate content was determined by trimethylsilation and gas chromatography (modified method of Underhill and Kirkland, 1971). / Land and Food Systems, Faculty of / Graduate

A 12S glycoprotein was isolated from commercial rapeseed meal (Brassica campestris) and examined by chemical, microscopical, and rheological methods. The molecular weight of the protein was estimated to be 129,200 daltons by conventional sedimentation equilibrium ultracentrifugation although the presence of higher molecular weight material was detected in the preparation. The 12S protein was found to be oligomeric, dissociating, into low molecular weight fragments in the presence of urea or sodium dodecyl sulfate. The protein aggregate was separated into subunits with apparent molecular weights of approximately 42,000, 37,600, 30,100, 17,400 and 12,200 by SDS gel electrophoresis. Electrophoretic patterns of non-reduced and reduced samples indicated the presence of intermolecular disulfide bonds although the cystine content was low. The 12S protein contained 12.9% (w/w) carbohydrate and reacted strongly when oxidized and treated with Schiff reagent. PAS-treated SDS gels indicated that most of the carbohydrate was present in one low molecular weight fragment. SDS immunoelectrophoretic analysis suggested that the glyco-peptide portion is located on the surface of the complex. Although the isolate contained a high molecular weight contaminant (17S), immunoelectrophoretic analysis resulted in the formation of one homogeneous pair of precipitin arcs. This would suggest that the 12S protein self-associates to form aggregates of higher molecular weight. In an attempt to separate the 17S and 12S fractions by gel filtration, a 33.9S protein was isolated, presumably the product of a self-associating system. SDS electrophoretic patterns of the 33.9S and 12S proteins were similar. Histochemical studies revealed that the 12S glycoprotein was present in some but not all of the cells of the intact rapeseed kernel. Schiff-positive aleurones were distributed randomly throughout the kernels. Transmission electron microscopy of negatively-stained specimens revealed that the protein was morula-shaped with a maximum particle diameter of 120Å The 12S rapeseed protein formed gels when dispersions of this material were heated. The rheological and ultra-structural examination of this phenomenon revealed that gel structure depended upon pH and ionic strength but to a lesser degree on low levels of urea or dithiothreitol. / Land and Food Systems, Faculty of / Graduate

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