Please read the abstract in the section 00front of this document / Thesis (PhD (Soil Science))--University of Pretoria, 2007. / Plant Production and Soil Science / unrestricted

Thesis (MSc)--University of Stellenbosch, 2001. / ENGLISH ABSTRACT: The goals of this project were to (i) determine maximum extractable neutral invertase (NI) activity in the sugarcane culm, (ii) sequence a cDNA encoding for the sugarcane NI (SNI), (iii) determine SNI copy number in the genome, (iv) describe SNI transcript and protein expression patterns throughout the plant, and (v) attempt to determine the contribution of hydrolysis to sucrose accumulation. SNI and sugars were extracted from the developing culm tissues of sugarcane, commercial variety N19. Tissues were divided according to developmental stage (internodes 3, 6 and 9) and anatomical differentiation (enriching for elongating, vascular or storage tissues). The lowest sucrose content was found in the core of the bottom of each of the internodes. The ratio between hexoses and sucrose was highest in the young internodes. In these internodes hexose content was higher in the bottom than the top. There was a significant correlation between sucrose content and NI. Fluxes involved in sucrose synthesis and hydrolysis were investigated. The hexoses glucose and fructose were supplied as a carbon source for tissue discs of young and maturing internodal tissues of sugarcane, varieties N19 and US6656-15. Sucrose content was 10-fold higher in maturing internodes of N19 than US6656-15. Calculated sucrose hydrolysis rates via invertase were higher in maturing internodes of US6656-15 than N19. Taking metabolic compartmentation into account, hydrolysis of sucrose via invertase made a significant contribution to the net turnover of sucrose. Along with this, it would appear that the ability to partition sucrose between the vacuole and cytosol causes a significant difference in sucrose content between varieties. A full-length cDNA for SNI was sequenced. This expressed gene showed significant homology to known NI sequences on both nucleic and amino acid levels. The SNI sequence did not contain the putative invertase catalytic amino acid sequence, suggesting it developed separately from the other classes of invertases. Approximately 1.8 kb of the SNI cDNA was incorporated into a vector suitable for direct bombardment into sugarcane tissue. Southern blot analysis showed the enzyme has a low copy number. SNI transcript expression was observed in all tissues of the sugarcane plant: roots, internodes, leaf roll and leaves. In culm tissues where sucrose content was low and hexose contents were high, SNI transcript and protein levels were high. This suggests that SNI is involved in growth metabolism. / AFRIKAANSE OPSOMMING: Die doel van die projek was om (i) maksimum ekstaheerbare neutrale invertase (NI) aktiwiteit in die suikerriet stingel te bepaal, (ii) die volgorde van 'n eDNA wat vir suikerriet NI (SNI) kodeer te bepaal, (iii) die SNI kopie-getal in die genoom te bepaal, (iv) SNI m- RNA en proteïenuitdrukkingspatrone deur die plant te beskryf, en (v) te poog om die bydrae van hidrolise op sukrose akkumulering te bepaal. SNI en suikers is geëkstraheer uit 'n kommersiële varieteit, N19. Weefsels was volgens ontwikkelingstadiums (internodes 3, 6 en 9) en anatomiese verskille (verryking vir groeiende, vaat- en bergings-weefsels) verdeel. Die laagste sukrose inhoud is in die middel van die onderste helfte van elke internode gevind. Die verhouding van heksoses tot sukrose was die hoogste in die jong internodes. Die inhoud heksoses was hoër in die onderste deel van die internode as die boonste deel. 'n Betekenisvolle korrelasie tussen sukrose inhoud en SNI is gevind. Flukse betrokke by sukrose sintese en hidrolise is ondersoek. Glukose en fruktose is as koolstofbron aan stingelweefsel van twee variëteite (US6656-15 and N19) toegedien. Sukrose-inhoud het tienvoudig tussen volwasse weefsels van die twee variëteite verskil. Hidrolise via invertase was hoër in ouer weefsels van US6656-15 as N19, en het In noemenswaardige bydrae tot sukroseomset gemaak. Die verdeling van sukrose tussen die vakuool en die sitosol kan moontlik 'n groot rol speel in die vermoë van die sel om sukrose te akkumuleer. Die volgorde van 'n volledige SNI eDNA is bepaal. The uitgedrukte geen het, op beide In nukleïen- en aminosuur vlak, betekenisvolle ooreenkoms getoon met ander bekende plant NI volgordes. Die SNI volgorde bevat nie die kenmerkende invertase katalitiese setel nie, wat daarop kan dui dat dit onafhanklik van ander klasse invertases ontwikkel het. Min of meer 1.8 kb van die SNI eDNA is in 'n vektor geskik vir bioliestiese transformering van suikerrietweefsel, geïnkorporeer. Southern klad analise het gewys dat die ensiem 'n lae kopiegetal op geen vlak het. SNI mRNA uitdrukking is waargeneem in elke weefseltipe van die suikerriet plant: wortels, internodes, blaarrol en blare. In stingelweefsels met lae sukrose- en hoë heksose-inhoud, was die vlakke van beide SNI-mRNA en -proteïen hoog. Dit dui daarop dat SNI moontlik betrokke is by groei-metabolisme.

A caracterização das etapas de produção da aguardente de cana de açúcar por meio da análise química dos destilados pode vir a ser utilizada na certificação da procedência da bebida e, consequentemente, no rastreamento do processo pelo qual a bebida foi submetida, fornecendo aos consumidores a garantia da qualidade e da conformidade do produto a ser consumido. Assim, a verificar o tipo de aparelho utilizado durante o processo de destilação, a identificar o tipo do processo fermentativo utilizado durante a etapa de fermentação do caldo de cana de açúcar, a comparar o perfil químico das frações de \"cauda\", \"coração\" e cabeça\' obtidas durante a destilação do caldo em alambiques, determinar a origem geográfica do destilado de acordo com os Estados onde o mesmo foi produzido e correlacionar o perfil químico e sensorial das amostras de aguardente, são os objetivos deste trabalho. Para a cerificação do processo de destilação, seis amostras diferentes de caldo de cana de açúcar fermentado (vinho) foram destiladas em dois aparelhos de destilação (alambique de cobre e coluna de aço inox), gerando 24 destilados (seis para cada fração de alambique - \"cabeça\", \"coração\" e \"cauda\"; e outros seis destilados de coluna). A composição química dos destilados obtidos a partir do mesmo vinho foi obtida utilizando técnicas cromatográficas (GC-FID, GC-MS e HPLC-UV-vis). Os dados analíticos foram submetidos à Análise de Componentes Principais (PCA) e à Análise Hierárquica de Grupos (HCA), as quais conduziram o agrupamento das amostras de acordo com seus perfis químicos e o tipo de aparelho utilizado no processo de destilação. Estas análises permitiram certificar que os diferentes processos de destilação caracterizam a composição química da cachaça, uma vez que a influência da etapa fermentativa foi eliminada. Para a avaliação da etapa de fermentação, foram utilizadas 105 amostras de aguardentes produzidas no Estado de São Paulo. Quarenta e cinco dessas amostras foram destiladas em colunas de aço inox, sendo que em 31 delas foi utilizado o fermento industrial fleischmann e, nas outras 14 amostras, utilizou-se o fermento natural, obtido a partir do processo denominado \"pé-de-cuba\". As 60 amostras restantes foram destiladas em alambiques de cobre. Desse total, em 28 delas, foi utilizado o fermento industrial; em outras 20, o fermento natural; em outras 12, utilizou-se uma mistura do fermento natural com o industrial. Os dados analíticos foram submetidos à Análise de Componentes Principais (PCA), à Análise Hierárquica de Agrupamentos (HCA) e à Análise Discriminante Linear (LDA), possibilitando a discriminação do tipo de processo fermentativo utilizado durante a fermentação do caldo de cana para as aguardentes destiladas em colunas de aço inox. O modelo químico de previsão, elaborado para o reconhecimento do tipo de processo fermentativo, foi capaz de identificar corretamente 83% das amostras destiladas em colunas de aço inox. No caso das aguardentes destiladas em alambiques de cobre, foi possível identificar o tipo de fermento com uma certeza de apenas 41%. Tal comportamento pode ser devido a uma descaracterização do destilado em virtude do processo de cortes realizado durante a etapa de destilação em alambiques. As frações de \"cabeça\", \"coração\" e \"cauda\", obtidas durante a destilação em alambiques, foram quimicamente caracterizadas através da analise das concentrações de 39 compostos orgânicos. Os resultados foram avaliados utilizando-se análise de variância (ANOVA), teste de Tukey, análise de componentes principais (PCA), agrupamento hierárquico (HCA) e análise discriminante linear (LDA). De acordo com PCA e HCA, os dados experimentais conduzem à formação de três agrupamentos. As frações de cabeça deram origem a um grupo mais definido. As frações coração e cauda apresentaram alguma sobreposição coerente com sua composição em ácidos. As habilidades preditivas de calibração e validação dos modelos gerados pela LDA para a classificação das três frações foram de 90,5 e 100%, respectivamente. Este modelo reconheceu, como fração \"coração\", doze das treze cachaças comerciais (92,3%), cujas qualidades sensoriais foram previamente reconhecidas, apresentando, portanto, potencial para a orientação do processo de cortes. Para o reconhecimento da região geográfica (Estado) onde a bebida foi produzida, foram utilizadas 50 amostras obtidas junto a diferentes produtores (sendo 15 oriundas do Estado de São Paulo, 11 de Minas Gerais, três do Rio de janeiro e outras três da Paraíba). Todas as amostras foram obtidas por fermentação natural, destiladas em alambique de cobre e não submetidas ao processo de envelhecimento. O tratamento dos dados por meio da Análise de Componentes Principais permitiu a observação da correlação entre o perfil químico dos destilados e a região onde os mesmos foram produzidos. KNN, SIMCA, PLS-DA, LDA foram os métodos de classificação utilizados na construção de modelos de predição cujos graus de acertos de cada um deles foram de 84%, 98%, 64%, 76% respectivamente. Os resultados mostram que, para as amostras em questão, é possível identificar a procedência regional das aguardentes de acordo com a composição química das mesmas. A correlação entre a composição química e os dados sensoriais de 28 amostras de cachaças foi investigada por meio de análise de componentes principais (PCA). Foi então elaborado um modelo químico usando análise discriminante linear (LDA) para classificar as amostras de cachaças de acordo com suas qualidades sensoriais. Este modelo apresentou habilidades preditivas de calibração e validação de 87,4 e 100%, respectivamente, e foi capaz de reconhecer a qualidade sensorial de maneira correta, 7 dentre 9 amostras comerciais previamente avaliadas sensorialmente, apresentando-se como uma ferramenta potencial alternativa para a avaliação das qualidades sensoriais de cachaças. / The chemical characterization of the sugarcane spirits\' production stages can be used to certify and consequently to tracking the process by which the distillate was submitted, providing to the consumers assurance and conformity of the product that will be consumed. Thus, the chemical profile comparison of sugarcane spirits from the same wine distilled in alembics and columns were evaluated in order to certify the apparatus influence in the distillate. For this six wines were distilled in two different distillation apparatus (alembic and column) producing 24 distillates (6 for each alembic fraction - head, heart and tail; 6 column distillates). The chemical composition of distillates from the same wine was determined using chromatographic techniques. Analytical data were subjected to Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA) allowing discrimination of four clusters according to chemical profiles. Both distillation processes influenced the sugarcane spirits chemical quality since two types of distillates with different quantitative chemical profiles were produced after the elimination of fermentation step influence. The traceability of the fermentative process during the production of Brazilian sugarcane spirits (cachaças) was investigated for different yeast strains of Saccharomyces cerevisiae. Two different distillation apparatus were used for this purpose: copper alembic stills and stainless steel columns. The data set (44 chemical compounds and 105 samples of sugarcane spirits) including products from column and alembic, treated with Principal Components Analysis showed that the concentrations of ethyl lactate, dimethyl sulfide and acetic acid are correlated with the natural fermentation process. For the samples distilled in stainless steel column, the first three principal components account for 77.7% of the total variance (PC1 - 54.9 %; PC2 - 13.4%; PC3 - 10.3%). Linear Discriminant Analysis using as chemical descriptors ethyl hexanoate, ethyl dodecanoate, ethyl lactate, ethyl octanoate, ethyl decanoate, isoamyl octanoate, dimethyl sulfide, isobutyl alcohol and isoamyl alcohol provides a robust chemical model able to correctly classify 83% of the cachaças according to their respective fermentation process. A less clear classification (predictive ability of 42%) was observed for the sugarcane spirits distilled in the alembic stills. Concentrations of 39 organic compounds were determined in three fractions (head, heart and tail) obtained from the pot still distillation of fermented sugarcane juice. The results were evaluated using analysis of variance (ANOVA), Tukey\'s test, principal component analysis (PCA), hierarchical cluster analysis (HCA) and linear discriminant analysis (LDA). According to PCA and HCA, the experimental data lead to the formation of three clusters. The head fractions give rise to a more defined group. The heart and tail fractions showed some overlap consistent with its acid composition. The predictive ability of calibration and validation of the model generated by LDA for the three fractions classification were 90.5 and 100%, respectively. This model recognized as the heart twelve of the thirteen commercial cachaças (92.3%) with good sensory characteristics, thus showing potential for guiding the process of cuts. In an attempt to pattern recognition of sugarcane spirits according their geographic origin region, chemical data for 24 analytes were evaluated in 50 cachaças samples produced following a similar procedure in selected regions of Brazil: São Paulo - SP (15), Minas Gerais - MG (11), Rio de Janeiro - RJ (11), Paraiba -PB (9) and Ceará - CE (4). Multivariate analysis was applied to the analytical results, and thus the predictive ability of different classification methods was evaluated. According to PCA treatment five groups wrer identified: chemical similarities were observed between MG and SP samples and between RJ and PB samples. CE samples presented a quite typical chemical profile. Considering all the 50 samples, Partial Linear Square Discriminant Analysis (PLS-DA) classified 64% of the samples correctly, K-Nearest Neighbor 84%, Linear discriminant Analysis (LDA) 76% and Soft Independent Modeling of Class Analogy (SIMCA) 98%. Therefore in this concept proof test, the proposed approach, based on chemical data was able of satisfactorily predict the geographic origin of sugarcane spirits. The correlation between the chemical composition and the sensory data for 28 cachaça samples was investigated using principal component analysis (PCA). A chemical model was then developed using linear discriminant analysis (LDA) to classify the distillate samples according to their sensory qualities. This model presented predictive abilities of calibration and validation of 87.4 and 100%, respectively, and was able to recognize correctly 7 out of 9 additional samples according to their sensory evaluations, showing itself as a potential alternative tool of recognizing cachaça sensory qualities.

A caracterização das etapas de produção da aguardente de cana de açúcar por meio da análise química dos destilados pode vir a ser utilizada na certificação da procedência da bebida e, consequentemente, no rastreamento do processo pelo qual a bebida foi submetida, fornecendo aos consumidores a garantia da qualidade e da conformidade do produto a ser consumido. Assim, a verificar o tipo de aparelho utilizado durante o processo de destilação, a identificar o tipo do processo fermentativo utilizado durante a etapa de fermentação do caldo de cana de açúcar, a comparar o perfil químico das frações de \"cauda\", \"coração\" e cabeça\' obtidas durante a destilação do caldo em alambiques, determinar a origem geográfica do destilado de acordo com os Estados onde o mesmo foi produzido e correlacionar o perfil químico e sensorial das amostras de aguardente, são os objetivos deste trabalho. Para a cerificação do processo de destilação, seis amostras diferentes de caldo de cana de açúcar fermentado (vinho) foram destiladas em dois aparelhos de destilação (alambique de cobre e coluna de aço inox), gerando 24 destilados (seis para cada fração de alambique - \"cabeça\", \"coração\" e \"cauda\"; e outros seis destilados de coluna). A composição química dos destilados obtidos a partir do mesmo vinho foi obtida utilizando técnicas cromatográficas (GC-FID, GC-MS e HPLC-UV-vis). Os dados analíticos foram submetidos à Análise de Componentes Principais (PCA) e à Análise Hierárquica de Grupos (HCA), as quais conduziram o agrupamento das amostras de acordo com seus perfis químicos e o tipo de aparelho utilizado no processo de destilação. Estas análises permitiram certificar que os diferentes processos de destilação caracterizam a composição química da cachaça, uma vez que a influência da etapa fermentativa foi eliminada. Para a avaliação da etapa de fermentação, foram utilizadas 105 amostras de aguardentes produzidas no Estado de São Paulo. Quarenta e cinco dessas amostras foram destiladas em colunas de aço inox, sendo que em 31 delas foi utilizado o fermento industrial fleischmann e, nas outras 14 amostras, utilizou-se o fermento natural, obtido a partir do processo denominado \"pé-de-cuba\". As 60 amostras restantes foram destiladas em alambiques de cobre. Desse total, em 28 delas, foi utilizado o fermento industrial; em outras 20, o fermento natural; em outras 12, utilizou-se uma mistura do fermento natural com o industrial. Os dados analíticos foram submetidos à Análise de Componentes Principais (PCA), à Análise Hierárquica de Agrupamentos (HCA) e à Análise Discriminante Linear (LDA), possibilitando a discriminação do tipo de processo fermentativo utilizado durante a fermentação do caldo de cana para as aguardentes destiladas em colunas de aço inox. O modelo químico de previsão, elaborado para o reconhecimento do tipo de processo fermentativo, foi capaz de identificar corretamente 83% das amostras destiladas em colunas de aço inox. No caso das aguardentes destiladas em alambiques de cobre, foi possível identificar o tipo de fermento com uma certeza de apenas 41%. Tal comportamento pode ser devido a uma descaracterização do destilado em virtude do processo de cortes realizado durante a etapa de destilação em alambiques. As frações de \"cabeça\", \"coração\" e \"cauda\", obtidas durante a destilação em alambiques, foram quimicamente caracterizadas através da analise das concentrações de 39 compostos orgânicos. Os resultados foram avaliados utilizando-se análise de variância (ANOVA), teste de Tukey, análise de componentes principais (PCA), agrupamento hierárquico (HCA) e análise discriminante linear (LDA). De acordo com PCA e HCA, os dados experimentais conduzem à formação de três agrupamentos. As frações de cabeça deram origem a um grupo mais definido. As frações coração e cauda apresentaram alguma sobreposição coerente com sua composição em ácidos. As habilidades preditivas de calibração e validação dos modelos gerados pela LDA para a classificação das três frações foram de 90,5 e 100%, respectivamente. Este modelo reconheceu, como fração \"coração\", doze das treze cachaças comerciais (92,3%), cujas qualidades sensoriais foram previamente reconhecidas, apresentando, portanto, potencial para a orientação do processo de cortes. Para o reconhecimento da região geográfica (Estado) onde a bebida foi produzida, foram utilizadas 50 amostras obtidas junto a diferentes produtores (sendo 15 oriundas do Estado de São Paulo, 11 de Minas Gerais, três do Rio de janeiro e outras três da Paraíba). Todas as amostras foram obtidas por fermentação natural, destiladas em alambique de cobre e não submetidas ao processo de envelhecimento. O tratamento dos dados por meio da Análise de Componentes Principais permitiu a observação da correlação entre o perfil químico dos destilados e a região onde os mesmos foram produzidos. KNN, SIMCA, PLS-DA, LDA foram os métodos de classificação utilizados na construção de modelos de predição cujos graus de acertos de cada um deles foram de 84%, 98%, 64%, 76% respectivamente. Os resultados mostram que, para as amostras em questão, é possível identificar a procedência regional das aguardentes de acordo com a composição química das mesmas. A correlação entre a composição química e os dados sensoriais de 28 amostras de cachaças foi investigada por meio de análise de componentes principais (PCA). Foi então elaborado um modelo químico usando análise discriminante linear (LDA) para classificar as amostras de cachaças de acordo com suas qualidades sensoriais. Este modelo apresentou habilidades preditivas de calibração e validação de 87,4 e 100%, respectivamente, e foi capaz de reconhecer a qualidade sensorial de maneira correta, 7 dentre 9 amostras comerciais previamente avaliadas sensorialmente, apresentando-se como uma ferramenta potencial alternativa para a avaliação das qualidades sensoriais de cachaças. / The chemical characterization of the sugarcane spirits\' production stages can be used to certify and consequently to tracking the process by which the distillate was submitted, providing to the consumers assurance and conformity of the product that will be consumed. Thus, the chemical profile comparison of sugarcane spirits from the same wine distilled in alembics and columns were evaluated in order to certify the apparatus influence in the distillate. For this six wines were distilled in two different distillation apparatus (alembic and column) producing 24 distillates (6 for each alembic fraction - head, heart and tail; 6 column distillates). The chemical composition of distillates from the same wine was determined using chromatographic techniques. Analytical data were subjected to Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA) allowing discrimination of four clusters according to chemical profiles. Both distillation processes influenced the sugarcane spirits chemical quality since two types of distillates with different quantitative chemical profiles were produced after the elimination of fermentation step influence. The traceability of the fermentative process during the production of Brazilian sugarcane spirits (cachaças) was investigated for different yeast strains of Saccharomyces cerevisiae. Two different distillation apparatus were used for this purpose: copper alembic stills and stainless steel columns. The data set (44 chemical compounds and 105 samples of sugarcane spirits) including products from column and alembic, treated with Principal Components Analysis showed that the concentrations of ethyl lactate, dimethyl sulfide and acetic acid are correlated with the natural fermentation process. For the samples distilled in stainless steel column, the first three principal components account for 77.7% of the total variance (PC1 - 54.9 %; PC2 - 13.4%; PC3 - 10.3%). Linear Discriminant Analysis using as chemical descriptors ethyl hexanoate, ethyl dodecanoate, ethyl lactate, ethyl octanoate, ethyl decanoate, isoamyl octanoate, dimethyl sulfide, isobutyl alcohol and isoamyl alcohol provides a robust chemical model able to correctly classify 83% of the cachaças according to their respective fermentation process. A less clear classification (predictive ability of 42%) was observed for the sugarcane spirits distilled in the alembic stills. Concentrations of 39 organic compounds were determined in three fractions (head, heart and tail) obtained from the pot still distillation of fermented sugarcane juice. The results were evaluated using analysis of variance (ANOVA), Tukey\'s test, principal component analysis (PCA), hierarchical cluster analysis (HCA) and linear discriminant analysis (LDA). According to PCA and HCA, the experimental data lead to the formation of three clusters. The head fractions give rise to a more defined group. The heart and tail fractions showed some overlap consistent with its acid composition. The predictive ability of calibration and validation of the model generated by LDA for the three fractions classification were 90.5 and 100%, respectively. This model recognized as the heart twelve of the thirteen commercial cachaças (92.3%) with good sensory characteristics, thus showing potential for guiding the process of cuts. In an attempt to pattern recognition of sugarcane spirits according their geographic origin region, chemical data for 24 analytes were evaluated in 50 cachaças samples produced following a similar procedure in selected regions of Brazil: São Paulo - SP (15), Minas Gerais - MG (11), Rio de Janeiro - RJ (11), Paraiba -PB (9) and Ceará - CE (4). Multivariate analysis was applied to the analytical results, and thus the predictive ability of different classification methods was evaluated. According to PCA treatment five groups wrer identified: chemical similarities were observed between MG and SP samples and between RJ and PB samples. CE samples presented a quite typical chemical profile. Considering all the 50 samples, Partial Linear Square Discriminant Analysis (PLS-DA) classified 64% of the samples correctly, K-Nearest Neighbor 84%, Linear discriminant Analysis (LDA) 76% and Soft Independent Modeling of Class Analogy (SIMCA) 98%. Therefore in this concept proof test, the proposed approach, based on chemical data was able of satisfactorily predict the geographic origin of sugarcane spirits. The correlation between the chemical composition and the sensory data for 28 cachaça samples was investigated using principal component analysis (PCA). A chemical model was then developed using linear discriminant analysis (LDA) to classify the distillate samples according to their sensory qualities. This model presented predictive abilities of calibration and validation of 87.4 and 100%, respectively, and was able to recognize correctly 7 out of 9 additional samples according to their sensory evaluations, showing itself as a potential alternative tool of recognizing cachaça sensory qualities.

An outline is given of the South African sugar industry, with particular emphasis on the unit operations which make up the industrial process for manufacturing sugar from cane. Current knowledge of the chemistry of soluble polysaccharides is reviewed and the structures of several polysaccharides, including starch, dextran, and pullulan, are discussed. It has been found that changes take place in the chemical composition of the juice in sugar cane (Saccharum officinarum) during post-harvest storage. With increasing storage time, there is a proportional decrease in the starch content of the juice, and a considerably larger proportional increase in the soluble polysaccharide content. The increased polysaccharide content was found to be due to a single glucan which, contrary to most previous publications on this subject, is definitely not a dextran. Following structural analysis, it has been established that the polysaccharide formed in stored cane had not been described before and the name "sarkaran" , derived from the Sanskrit word "Sarkara", meaning "sugar" is proposed for it. The polysaccharide was isolated from cane juice by precipitation with ethanol after the starch in the juice had been removed by centrifugation. The polysaccharide was purified by repeated dissolution in water and reprecipitation with ethanol. Analysis by gel chromatography resulted in a single symmetrical peak, indicating that the isolated polysaccharide is homogeneous. This was confirmed by hydrolysing fractions representing a section of the ascending and a section of the descending part of the peak of the chromatogram, using the enzyme pullulanase. Chromatographic separation and quantitative analysis of the isolated oligosaccharides showed that the compositions of the two enzymes digests were identical. Acid hydrolysis of the polysaccharide resulted in a single hexose. This was identified as glucose by paper chromatography, comparing the Rf value with that of pure glucose. Confirmation was obtained by comparing the osazone with that of glucose, using microscopic examination and determination of the melting points. Paper electrophoresis showed the molecule to be uncharged. Several techniques, both absolute and non absolute, were used to determine the molecular weight of the polysaccharide. A method involving viscosity determination indicated a molecular weight of 34 000 while a figure of 50 000 was obtained by gel chromatography on a Sephadex column, comparing the peak elution volume of the polysaccharide with that of dextrans of a defined molecular weight. Both these techniques are non absolute and yield rough estimates of the molecular weight. Osmometric measurement, an absolute method, showed the number average molecular weight to be 51 500. An absolute value for the weight average molecular weight of 250 000 was obtained by light scattering techniques. Data from the light scattering experiments were also used to determine a value of 200 - 250 A for the radius of gyration RG of the polysaccharide. End group analysis after exhaustive methylation resulted in a value of 24 000 for the number average molecular weight Mn. This indicates either that some degradation of the polysaccharide molecule occurs , during the methylation procedures or that there is a certain degree of association between individual molecules. Periodate oxidation showed that 32 percent of the glucosidic linkages are in ( 1 + 6 ) position. The polysaccharide was exhaustively methylated by several Haworth methylations followed by a number of Kuhn methylations. The fully methylated product was methanolysed and the methyl glucopyranosides analysed by gas liquid chromatography. The results were compared with those obtained from fully methylated starch and dextran. From the absence of disubstituted methyl derivatives in the methanolysate it was concluded that the polysaccharide is an unbranched glucan. From the quantities of Methyl 2,3,4,6 tetramethyl-O-Dglucopyranoside, Methyl 2,3,6, trimethyl-O-D-glucopyranoside and Methyl 2,3,4? trimethyl-0-D-glucopyranoside, it was concluded that the only linkages in the glucan are ( 1 + 4 ) and ( 1 + 6 ) and that these are present in the ratio 68:32. Enzymic hydrolysis, using pullulanase, was followed by paper chromatographic separation. Quantitative determination of the oligo-saccharides present in the enzyme digest resulted mainly in two oligosaccharides, maltotriose and maltotetraose, in nearly equal proportions. For this reason it was postulated that the polysaccharide is a maltotriose-maltotetraose polymer, and that the individual units are linked in ( I + 6 ) position, a linkage for which pullulanase is specific in certain configurations. The sequence of the maltotriose and maltotetraose units in the polymer has not been investigated further, although this could be carried out by partial acid hydrolysis, followed by isolation and identification of the various oligosaccharides formed. An alternate method for the determination of the sequence of the monomers is discussed. It was subsequently shown that the linkages in the polysaccharide are in the a configuration. The polysaccharide is highly dextra rotary and the magnitude of the rotation is comparable to that of other polysaccharides linked in a position, . such as starch and dextran. Infrared spectroscopy was used to confirm the configuration. The spectrogram of the polysaccharide contained an absorption peak at 840 cm-1 , which is typical of the a-anomeric absorption occurring, for example, in the IR spectrum of starch. The spectrogram exhibited no absorption peak at 891 cm-1 , the wavelength typical of the B-anomeric absorption in the IR spectrum of cellulose. In addition, it was found that all polysaccharides containing a ( 1 + 4 ) linkages show an absorption peak at 700 cm 1. This absorption peak was absent in all IR spectra obtained from various dextrans. This phenomenon has not been reported previously and it is suggested that the presence of this absorption peak in the IR spectrum of a glucan can be used to support the evidence of the presence of a( 1 + 4 ) linkages. It was not possible to correlate the formation of the polysaccharide with the occurrence of a specific micro organism. It is suggested that the formation of the polysaccharide is the result of enzymic reactions in the sugar cane after harvesting. The investigation of the composition of juices from deteriorated cane has not been confined to polysaccharides. Ethanol has been isolated from the juice of some samples of stored cane which had been burnt before harvesting. The ethanol was isolated by fractional distillation and identified by measurement of the boiling point. It was confirmed, by the formation of the molybdate-xanthate complex, that the product isolated was an alcohol. The identification was further confirmed by oxidising the ethanol to acetic acid and proving the identity of the acids by paper chromatography. It has been shown that, with the exception of two acids, the carboxylic acid composition of cane juice remains unaltered during post-harvest storage of the cane. The two exceptions , succinic and aconitic acids, were identified from their melting points and by specific spot tests. Ion exchange was used to isolate the acids from the juice. The eluate from the ion exchange column was concentrated and the acids separated by liquid-liquid chromatography, using a silica gel column. The levels of both aconitic and succinic acids were found to increase during the early period of storage but decreased again slowly thereafter. The percentage change was greater in the case of succinic acid, although aconitic acid was the most abundant carboxylic acid in the juice. Lactic acid was absent from the cane juices analysed. This is surprising, as lactic acid is a common product of the metabolism of carbohydrates by micro organisms. It is suggested that the changes in acid composition during the storage of harvested cane are caused by deactivation of enzymes of the Krebs cycle. Post-harvest deterioration of sugar cane can have serious consequences which can affect the whole Sugar Industry. Not only is crystallisable sugar lost but the products of the deterioration have adverse effects on factory processing and laboratory analysis. The problem, which will become more acute with the introduction of mechanical cane harvesting, can only be resolved through the cooperative efforts of all the parties concerned. / Thesis (Ph. D.)-University of Natal, Durban, 1973.

Sugarcane is challenged by a number of phytopathogenic bacteria and viruses that are best managed by the development of resistant varieties. Genetic engineering is a promising strategy in such breeding efforts, as it allows novel mechanisms of resistance not available in any parent germplasm to be introduced into the crop. DNA sequences encoding cystatin from papaya (Carica papaya), and pleurocidin from the winter flounder (Pleuronectes americanus) were envisaged as transgenes in this work due to their theoretical potential to increase sugarcane resistance to viruses and pathogenic or opportunistic bacteria, respectively. Cystatin is a cysteine proteinase inhibitor. Cysteine proteinases are used by potyviruses to cleave the polyprotein gene product, an essential step in the viral life cycle. Constitutive expression of cystatin may therefore lend the host plant resistance to a range of potyviruses, including the economically important pathogen sugarcane mosaic virus (SCMV). Pleurocidin is an amphipathic, α-helical, cationic peptide, with broadspectrum anti-bacterial activity at physiological pH. By binding to the cell membranes of both Gram positive and Gram negative bacteria, pleurocidin disrupts the membrane potential, causing it to become more permeable, especially to cations, leading to death of the bacterial cell. Initial microbiological bioassays showed that pleurocidin has inhibitory and bactericidal effects on the organisms which cause leaf scald (Xanthomonas albilineans), gumming disease (Xanthomonas campestris pv. vasculorum) and post-harvest sucrose conversion in sugarcane, as well as inhibitory effects against Leifsonia xyli ssp. xyli, which causes ratoon stunting disease (RSD). For transformation vector construction, the cystatin and pleurocidin coding sequences were altered so that their start codons were in the most favourable consensus context for expression in monocotyledonous plants. In the case of pleurocidin, an extracellular peroxidase signal sequence was attached. The prepared sequences were spliced into the vector pUBI510 in which the gene of interest is driven by the CaMV 35S promoter linked in tandem to a derivative of the maize ubiquitin promoter. The constructs generated were named pUBI510-cys3 and pUBI510-pleur08 respectively. The plasmid structures were confirmed using restriction endonuclease analysis and DNA sequencing. Since the transformation of sugarcane is known to be inefficient, two routes of morphogenesis for the production of somatic embryos were compared in the transformation procedure. These were (1) indirect embryo production via callus and (2) the direct and indirect production of embryos from transverse sections of leaf roll. Field grown sugarcane varieties N12 and NCo376 were the source of explant material. Plasmids pUBI510-cys3 and pUBI510-pleuro8 were respectively co-delivered by microprojectile bombardment with the antibiotic resistance selection plasmid pUBIKN containing the neomycin phosphotransferase gene (npt-II). Cultures were maintained in the dark on selection medium containing various concentrations of the antibiotic geneticin (G418) for several weeks before being allowed to regenerate in the light. Plantlets coming through selection were hardened off in the glasshouse when approximately 100mm high. Primer pairs for amplification of the cystatin insert were designed in various ways. The primer pair which ultimately proved most useful was designed to be complementary to the 5' and 3' ends of the papaya cystatin nucleotide sequence. Primer Premier analysis of a sorghum cystatin sequence provided additional possible primers. A further pair for potential future use was devised based on complementarity to conserved regions on maize cystatins 1 and 2, sorghum, rice, and papaya cystatins. The nucleotide sequence was constructed using the most common monocotyledon codon permutations for each amino acid. Pleurocidin primers were designed to be complementary to 5' and 3' regions of the nucleotide sequence encoding the pleurocidin pre-pro-protein. PCR and RT-PCR protocols for the detection of transgenes and transcript production in putative transgenic plants were developed using these primers. No plants survived selection via the callus route, although some were regenerated via direct embryogenesis. Putative transformed plants were analysed using PCR to test for the presence of integrated transgenes and Southern hybridization to determine transgene copy number. Both types of transgene were reproducibly detectable by PCR in DNA from some immature plants, but results were negative in DNA from those same plants when mature. Southern hybridization analysis detected the cystatin transgene in DNA from immature plants but no transgenes were detected in up to 20 µg DNA from mature plants. Single copy constructions of the transgenes in backgrounds of non-transformed DNA were detectable by both PCR and Southern hybridization analysis. Overall, PCR, RT-PCR and Southern hybridization results indicated that the plants regenerated fell into two categories: non-transformed plants that had survived selection (escapes) and chimaeric individuals with a component of both transformed and non-transformed cells, in which the transgene had probably become diluted during plant development under non-selective conditions. A method for extracting leaf exudates was tested, in conjunction with a cysteine proteinase assay to detect the presence of cystatin transgenes in the intracellular spaces of sugarcane leaves of confirmed transformants. Although it could not be applied within the scope of this project, this assay will prove useful in future work. / Thesis (M.Sc.)-University of Natal, Durban, 2002.

The sugar industry transports in excess of 20 million tons of sugarcane per annum, equating to approximately 800 000 road consignments. This entails substantial expenditure on vehicle capital and operational costs. There exists substantial scope to redesign vehicle configurations to reduce the vehicles tare mass and optimise the process of cane transportation. These modifications could potentially save the industry approximately Rl36 million per annum, and in addition will increase a vehicles lifespan, performance and speed. This project is one aspect of a larger project organised by the South African Sugarcane Research Institute, with the general aim of optimising the entire sugarcane transportation system. Aspects of this particular project include literature research as well as field investigation into the various sugarcane transportation systems in South Africa and throughout the world. The design of a cane haulage vehicle will be analysed and optimised, using tools such as finite element analysis. The aims of this project include the investigation of the engineering design issues with respect to vehicle/trailer configurations, and the design of an optimised cane haulage vehicle which increases the efficiency of raw sugarcane transportation in South Africa. / Thesis (M.Sc.)-University of KwaZulu-Natal, Durban, 2008.

Crop rotation is not commonly practised in the sugarcane industry in South Africa. It has, however, proven to be beneficial to other crops in South Africa. The objective of this study was to determine the impact of soybean-sugarcane crop rotation on selected physiological and phenological indicators of sugarcane performance and its subsequent effect on cane and estimated recoverable crystal (ERC) yields. A field trial was conducted at Mount Edgecombe, where soybean cultivar A5409RG and sugarcane cultivar NCo376 were planted under drip irrigation with different management practices. After the soybean crop, the following sugarcane crop was planted and fertilized with different levels of nitrogen (N) fertilizer (50% and 100% of the recommended N rate). The effects on sugarcane growth were recorded by taking into consideration date of emergence, plant height, tiller population, leaf N, plant performance index and chlorophyll content. Sugarcane yield and quality at harvest were also evaluated. Tiller population in all crop rotation treatments at Mount Edgecombe weresignificantly (P<0.05) higher than the monocrop treatment. There was a trend of increased leaf N in all of the cane-after-soya (crop rotation) crops compared to the cane-after-cane (monocrop) treatment, although this was not significant. A similar pattern was obtained with respect to the chlorophyll content and plant performance index. Sugarcane yields at Mount Edgecombe did not differ significantly between monocrop and crop rotation treatments. Crop rotation with soybean is beneficial for cane production, but its long term impact on soil quality and farm economy requires further investigation. / M.Sc.Agric. University of KwaZulu-Natal, Pietermaritzburg 2013.

Long delays between harvesting and crushing of sugarcane lead to excessive deterioration in the quality of sugarcane. The aim of this project was to develop a computer based model of sugarcane harvesting and delivery systems that could be used to investigate methods of reducing harvest-to crush delays. A literature review was conducted and simulation modelling was chosen as the most appropriate modelling technique for the situation of sugarcane harvesting and delivery and the purposes of this project. The Arena modelling system was chosen as the simulation software with which to construct the model. A model was developed on the scale of a particular sugar mill and the area of farms supplying it with cane. The Sezela mill on the south coast of KwaZulu-Natal, South Africa was chosen as a case study on which to develop and test the model. The model integrated a harvesting and transport section which represented all the individual farms or combinations of farms in the area with a millyard section. After the model had been verified and validated, it was used to investigate the effect of a number of different scenarios of harvesting and delivery systems and schedules on harvest-to-crush delays in the Sezela mill area. The results of the experimental runs performed with the model indicated that the most significant decreases in harvest-to-crush delays could be brought about by matching harvesting, delivery and milling cycles as closely as possible. It was also evident that burn-to-cut delays where daily burning is not practised constitute a large proportion of overall harvest-to crush delays. The model proved to be useful in making comparisons between systems and in providing a holistic view of the problem of harvest-to-crush delays. Recommendations for future developments of the model include adding a mechanical harvesting component and making the model more easily applicable to other mill areas. / Thesis (M.Sc.Eng.)-University of Natal, 1998.

Typescript. / Thesis (Ph. D.)--University of Hawaii at Manoa, 1987. / Bibliography: leaves 157-167. / Photocopy. / Microfilm. / xiii, 167 leaves, bound ill. 29 cm