published_or_final_version / Botany / Doctoral / Doctor of Philosophy

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The presence of mucilaginous material in the seed coat of canola cv. Candle has been associated with storage and mold infestation problems. This study examined the yield of mucilage from canola cv. Candle and some of its chemical and physical properties. Canola seeds were extracted for 16 hours with water using a seed:water ratio of 1:18 or heat-treated prior to water extraction using a seed:water ratio of 1:7. The mucilage was precipitated with 4 volumes of 95% ethanol and recovered by centrifugation at 3500 x g and 23 C for 10 minutes. A twofold increase in the yield of mucilage (1.33%) was obtained for the heat-treated seeds compared to (0.69-0.72%) for the unheated canola seeds. The heat-treated canola seeds were subjected to different extraction times from 4 to 16 hours using a seed:water ratio of 1:7. Approximately 63.8% of the total extractable rnucilage was obtained after the first 4 hours. No significant differences (P<0.05) were observed in the yield of mucilage between 4 hour extraction intervals. A significant difference (P<0.05) however, was evident in the yield of mucilage between 8 and 12 hour extraction intervals. The total yield of mucilage obtained at the end of the 16 hour extraction period was 1.16% Proximate analysis of canola mucilage showed it contained moisture (8.2%), protein (18.2%), carbohydrate (30.6%), ash (29.4%) with the remainder (13.6%) unidentified. No significant differences (P<0.05) were observed in either the protein or carbohydrate content of mucilage throughout the 16 hour extraction period. This suggested the mucilage was homogeneous with respect to protein and carbohydrate content. Analysis of the carbohydrate composition by gas chromatography showed that with the exception of rhamnose, no significant (P<0.05) differences between the individual monosaccharides over the different extraction intervals. The monosaccharide composition of canola mucilage was galactose (31.7%) rarabinose (28.9%), glucose (14.9%), mannose (9.7%), rhamnose (4.5%), xylose (3.7%) with the remaining 7.1% unidentified . Purification of mucilage was accompanied by a two and threefold increase in rhamnose and unidentified fractions respectively. A marked decrease in the other monosaccharides was observed for the purified material. The flow curve of a 0.5% solution of canola mucilage exhibited a shear thickening property. Canola mucilage was non-Newtonian in behaviour up to a shear rate corresponding to 350 rpm while at higher rate of shear it was Newtonian. The viscosity of a 0.5% solution of canola mucilage within the Newtonian range was 4 cp. Canola mucilage reduced surface tension and interfacial tension of a corn oil:water system . The interfacial tension value using canola mucilage was 9.5 dynes/crn which was similar to mustard mucilage (8.5 dynes/cm). The ability of canola mucilage to reduce interfacial tension was responsible for the formation of a stable salad dressing incorporating canola mucilage as emulsifier.

The presence of mucilaginous material in the seed coat of canola cv. Candle has been associated with storage and mold infestation problems. This study examined the yield of mucilage from canola cv. Candle and some of its chemical and physical properties. Canola seeds were extracted for 16 hours with water using a seed:water ratio of 1:18 or heat-treated prior to water extraction using a seed:water ratio of 1:7. The mucilage was precipitated with 4 volumes of 95% ethanol and recovered by centrifugation at 3500 x g and 23 C for 10 minutes. A twofold increase in the yield of mucilage (1.33%) was obtained for the heat-treated seeds compared to (0.69-0.72%) for the unheated canola seeds. The heat-treated canola seeds were subjected to different extraction times from 4 to 16 hours using a seed:water ratio of 1:7. Approximately 63.8% of the total extractable rnucilage was obtained after the first 4 hours. No significant differences (P<0.05) were observed in the yield of mucilage between 4 hour extraction intervals. A significant difference (P<0.05) however, was evident in the yield of mucilage between 8 and 12 hour extraction intervals. The total yield of mucilage obtained at the end of the 16 hour extraction period was 1.16% Proximate analysis of canola mucilage showed it contained moisture (8.2%), protein (18.2%), carbohydrate (30.6%), ash (29.4%) with the remainder (13.6%) unidentified. No significant differences (P<0.05) were observed in either the protein or carbohydrate content of mucilage throughout the 16 hour extraction period. This suggested the mucilage was homogeneous with respect to protein and carbohydrate content. Analysis of the carbohydrate composition by gas chromatography showed that with the exception of rhamnose, no significant (P<0.05) differences between the individual monosaccharides over the different extraction intervals. The monosaccharide composition of canola mucilage was galactose (31.7%) rarabinose (28.9%), glucose (14.9%), mannose (9.7%), rhamnose (4.5%), xylose (3.7%) with the remaining 7.1% unidentified . Purification of mucilage was accompanied by a two and threefold increase in rhamnose and unidentified fractions respectively. A marked decrease in the other monosaccharides was observed for the purified material. The flow curve of a 0.5% solution of canola mucilage exhibited a shear thickening property. Canola mucilage was non-Newtonian in behaviour up to a shear rate corresponding to 350 rpm while at higher rate of shear it was Newtonian. The viscosity of a 0.5% solution of canola mucilage within the Newtonian range was 4 cp. Canola mucilage reduced surface tension and interfacial tension of a corn oil:water system . The interfacial tension value using canola mucilage was 9.5 dynes/crn which was similar to mustard mucilage (8.5 dynes/cm). The ability of canola mucilage to reduce interfacial tension was responsible for the formation of a stable salad dressing incorporating canola mucilage as emulsifier.

Thesis (Ph. D.)--University of Hong Kong, 1999. / Includes bibliographical references (leaves 108-127).

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