Th. 3e cycle--Linguistique--Paris--INALCO, 1987.

Th.--Linguistique--Paris 3, 1987. / Bibliogr. p. 577-585. Index.

Thèse compl.--Lettres--Paris, 1960. / Bibliogr. f. 244-247. Glossaire f. 233-243.

Thesis (MTech (Food Technology))--Cape Peninsula University of Technology, 2018. / The aim of this study was to produce Bambara groundnut (BGN) starch-catechin complex using chemical initiators (ascorbic acid and hydrogen peroxide) and cyclodextrin (alpha and beta) with the view to obtain a functional ingredient for the food industry. BGN starch was successfully extracted from BGN flour through dry milling method, yielding 32% of BGN starch. Native BGN starch was chemically modified using ascorbic acid (1% w/w) and hydrogen peroxide (165% w/w) as redox, biocompatible initiator for grafting catechin to the BGN starch. In addition, cyclodextrin (alpha and beta) were also used as initiators for modifying BGN starch through complexation methods. Complexation methods used included the microwave, co-evaporation and kneading. The characterization of native and modified BGN starches was carried out by performing scanning electron microscopy, powder X-ray diffraction, Fourier Transform Infrared (FTIR) and fluorescence spectroscopy analysis. Functional, thermal and rheological properties of native and modified BGN starches were evaluated. The pasting properties of BGN starches were determined using the Rapid Visco Analyser (RVA). According to the SEM profile, native BGN starch had round, oval and elliptical shapes typical for legume starches. Native BGN starch displayed a typical type-C crystallinity which is common among legumes with strong peaks at 2θ of 15o, 17o and 23o. BGN starches modified through complexation methods had sharper peaks indicating an increase in starch crystallinity; however, following chemical modification there was loss in starch crystallinity which was evidenced by the amorphous region in the chemically modified BGN starches. Structure of native and modified BGN starches was confirmed by FTIR. The FTIR spectra of native BGN starch showed variable peaks at 3285.34 cm-1, 2931.69 cm-1, 1634.36 cm-1, 1336.77 cm-1 which are attributed to OH stretching, C-H stretching, water bending vibrations and C-O stretching, respectively. Furthermore, the FTIR results confirmed that native BGN starch is made up of glucose molecules just like all other starches. All modified BGN starches displayed a new absorption peak at 1020 cm-1 wavelength, thus indicating that starch modification was successful. On the other hand, all BGN starch-catechin complexes displayed a new absorption peak in the range of 1520 -1560 cm-1, attributed to the C-C stretching within the aromatic ring of the catechin. The successful grafting of catechin to BGN starch was also confirmed by the fluorescence spectroscopy results, where all the BGN starch-catechin complexes had an emission peak at 320 nm while native BGN starch had an emission peak at 270 nm. Antioxidant capacity of BGN starch was determined through DPPH and ORAC antioxidant assays. Within the DPPH assay, the antioxidant activity ranged from 2.26 to 38.31 μmol TE/g. The antioxidant activity of modified BGN starch-catechin complexes was significantly (p ≤ 0.05) higher than the ones modified without catechin. On the other hand, within the ORAC assay, the antioxidant activity ranged from 0.07 to 126.71 μmol TE/g. As opposed to the results obtained in DPPH assay, the antioxidant activity of chemically modified BGN starch-catechin complexes was significantly (p ≤ 0.05) higher than that of complexed BGN starch-catechin complexes. Chemical modification significantly increased the swelling capacity of native BGN starch while complexation methods significantly reduced it.

Diss.--Berlin--Freie Universität, 1989. / Bibliogr. p. 150-155.

Thesis submitted in fulfilment of the requirements for the degree Master of Technology: Food Technology in the Faculty of Applied Sciences at the Cape Peninsula University of Technology / The aim of this study was to evaluate bambara groundnut [BGN] non-starch polysaccharides [NSP] subject to the incorporation into model and food systems with a view to establish their functional and physicochemical properties. BGN insoluble dietary fibre [BGNIF] and soluble dietary fibre [BGNSF] were successfully extracted from four varieties (black-eye: BLE, red: RED, brown: BRN and brown-eye: BRE). Physicochemical properties evaluated revealed the high bulk density of all BGNIF and BGNSF varieties, which could contribute to cost-effective packaging. The microstructures of BGNIFs were irregular in shape with different sizes. The colour parameters (lightness, redness, yellowness, chroma and hue angle) differed significantly [p ≤ 0.05] across all BGNIF and BGNSF varieties; and indicated a yellowish-red colour for BGNIFs and a light yellow colour for BGNSFs. Negligible amounts of condensed tannins [CT] were found in BGNIFs (0.014 – 0.160 mg.g-1). Higher amounts polyphenols [PP] were present in BGNSFs (45.42 – 55.90 mg.g-1 gallic acid equivalents [GAE]) compared to the amount PP in BGNIFs (6.14 – 15.56 mg.g-1 GAE). Major sugars identified were arabinose/galactose, xylose and mannose in BGNIFs, and xylose and mannose in BGNSFs. The functional properties evaluated revealed high swelling capacity of BGNIFs (6.37 – 7.72 ml.g-1) and no significant [p > 0.05] difference in water retention capacity. Fat absorption capacity ranged from 1.38 – 1.52 g oil.g-1 dry weight for BGNIFs and 4.04 – 4.55 g oil.g-1 dry weight for BGNSFs. Variability in BGNIF (91.2%) and BGNSF (79.4%) physicochemical and functional properties could both be explained by two principal components (BGNIF component 1: PP, redness, yield; and component 2: xylose, yellowness and chroma; BGNSF component 1: yellowness, chroma, mannose content; and component 2: redness, fat absorption and fructose content). Following an IV optimal mixture design, an optimum white bread formulation was obtained using 59.5% water, 4.3% yeast and 8.5% BGNIF. Bread enriched with the four BGNIF varieties (BLE, RED, BRN and BRE) were tested for several physicochemical properties. Significant [p ≤ 0.05] differences existed between the control and BGNIF enriched loaves for crumb grain characteristics (including pore area distribution, feret angle, circularity, roundness and aspect ratio). Specific loaf volume of BGNIF enriched loaves ranged from 3.33 – 3.85 ml.g-1 and were significantly [p ≤ 0.05] lower compared to the control bread (4.16 ml.g-1). Favourable texture characteristics obtained with the BGNIF enriched breads were lower hardness, chewiness and gumminess compared to the control loaf. Crust and crumb colour parameters (lightness, redness, yellowness, chroma and hue angle) were significantly [p ≤ 0.05] different across all loaves. BRE BGNIF bread (3.43 ± 0.20) had the significantly [p ≤ 0.05] lowest crumb colour difference compared to the control bread; whilst BRN (1.72 ± 0.42) and BRE (2.44 ± 0.78) loaves had the lowest significant [p ≤ 0.05] crust colour difference compared to the control. Favourable chemical properties were the high total dietary fibre [TDF] (7.14 – 8.33%) content of all BGNIF enriched loaves compared to the control loaf (4.96%). Significant [p ≤ 0.05] differences were also observed for some loaves for moisture content, condensed tannins and polyphenol content. Variability in bread physicochemical properties was differentiated by three components (component 1: bread textural properties; component 2: specific loaf volume and bread lightness; component 3: crumb colour parameters) which accounted for a cumulative variation of 92.8%. All bread loaves were also sensorially acceptable as rated moderately like to like very much (>3 rating on a 5-point hedonic scale) by consumers for all parameters (appearance, crust and crumb colour, aroma, taste, texture and overall acceptability) evaluated. Furthermore, brown BGNSF was tested for stabilising effects in an orange beverage emulsion. BGNSF and orange oil were varied at two levels each based on a 22 augmented factorial design and the effects determined on the equilibrium backscattering [BS] flux as emulsion stability indicator. The BS profiles which resulted from the Turbiscan stability analysis revealed flocculation at low rates as the major destabilisation mechanism. The optimal formulation producing a stable emulsion was identified as low oil (6%) and high BGNSF (30%) concentrations. The objective of this study was therefore achieved and showed that positive physicochemical and functional properties are associated with BGNIF and BGNSF from black-eye, red, brown and brown-eye varieties. Furthermore, the incorporation of BGN fibres in white bread and a beverage emulsion was shown to contribute positive technological properties in these systems.

Dissertation--Bayreuth, 1997. / Bibliogr. p. 359-372.

Bambara groundnut (Vigna subterranea [L.] Verdc.) is an under-utilized indigenous African legume crop which has substantial potential to contribute to food security in sub-Saharan Africa. The crop is well adapted to severe agro-ecologies and grows where other legumes may not survive. The seed is highly nutritious with an ideal balance of carbohydrate (55-72%), protein (18-20%) and fats (6-7% oil), which is particularly beneficial in balancing protein deficiencies in cereals. Also, the seed contains essential and non-essential amino acids of about 33% and 66%, respectively. These attributes make Bambara groundnut an ideal crop to alleviate food insecurity, and to reduce protein malnutrition in rural communities of Africa. However, small-scale farmers grow low-yielding landraces in most production regions in sub-Saharan Africa. Bambara groundnut landraces exist as heterogeneous mixtures of seeds of a few to several seed morpho-types that embrace wide genetic potential for breeding. The objectives of this study were: 1) to determine the production status and constraints associated with Bambara groundnut production in Kano State of Nigeria through the use of a participatory rural appraisal (PRA); 2) to determine the genetic diversity of Bambara groundnut landraces through seed morphology; 3) to assess the inter- and intra-genetic diversity of the Bambara groundnut landraces; 4) to determine the yield and yield component responses among selected Bambara groundnut genotypes, 5) to determine the genomic diversity in Bambara groundnut landraces, using simple sequence repeat (SSR) markers; and 6) to develop a crossing protocol. Using a structured questionnaire, 150 Bambara groundnut farmers were interviewed. The respondents interviewed were male and aged between 36 to 50 years, while Qur’anic education was the most popular among them. Most of the farmers practiced a combination of sole and mixed cropping, and allocated between 0.38 to 1.68 hectares of land to Bambara groundnut growing. They selected Bambara groundnut landraces, especially looking for large seeds that were pure and oval in shape, with a cream seed coat colour and which were early maturing. A total of 27 diverse landraces bearing different names were identified in the hands of the farmers. Most popular among them were Gurjiya, Kurasa, Hawayen-Zaki, Fara Mai-Bargo and Silva. Production was largely for home consumption and for sale on local markets. Common production constraints of the crop were identified as a lack of improved varieties (70.7%), frequent droughts (9.3%), low yield (4%) and limited access to large markets (3.3%). Diverse collections of Bambara groundnut landraces from seven geographic origins were characterized using seed morphology, including seed coat, seed eye colour and pattern, and hilum colour and pattern. Out of 58 original seedlots, a total of 353 different seed morpho-types were further identified. The selected morpho-types- can be used for large-scale production or true-to-type lines could be used in genetic improvement of the crop. Genetic variability within- and between-landraces was investigated among 262 Bambara groundnut landraces, forty nine were studied for agronomic traits, and 213 were investigated for pod and seed variability. Most (47.9%) of the landraces developed pods with a point on one pole, and a round end on the other. Most had a creamy (37.1%) and yellow (76.1%) pod colour, and the pods were usually rough textured, and contained an oval seed. A further 158 landraces were evaluated for leaf morphology where 49.4% had round leaves, while 21.5% had elliptic leaves, with 55.7% of the landraces being heterogeneous, possessing more than one form of leaf shapes. These discrete characters can be utilized for genetic studies and improvement of Bambara groundnut. Single plant selections of 49 Bambara groundnut genotypes were evaluated for yield and yield components using 26 yield and yield related traits. Highly significant variations (P<0.001) were detected among the genotypes for canopy spread, petiole length, weight of biomass, seed weight and seed height. Principal component analysis (PCA) identified nine useful components, where two components, PC1 and PC2, contributed strongly to the total variation, at 19% and 14%, respectively. The PCA revealed that leaf colour at emergence, petiole colour, leaf joint pigmentation and calyx colour were highly correlated with PC1, while seed length, seed width and seed height had strong association with PC2. Both the principal component and cluster analyses showed that most genotypes associated with one another with respect to agronomic and seed yield traits, irrespective of geographical location. The genotypes 211-57, MO9-4 and TV-27 displayed high seed yield performances, while TV-93 and 45-2 had higher biomass production. These genotypes can be used as breeding lines to enhance productivity of Bambara groundnut. Fifty Bambara groundnut genotypes, representing seven geographical regions across Africa, were genotyped using five pre-selected polymorphic simple sequence repeat (SSR) markers developed specifically for Bambara groundnut. The results detected a total of 53 alleles among the 50 Bambara groundnut genotypes, while the neighbor-joining analysis generated seven major genetic groups, which were clustered regardless of their geographic origin. Close relationship were found between 211-68 on one hand and 211-83-2, N211K and M09-3 with 211-68 on the other. Genotypes M02-3, 211-55-1 and 211-57 displayed close similarities. These associations suggested the likelihood that the two pair groups had common origins or may possess similar genes. A preliminary protocol was developed for crossing Bambara groundnut using eight selected parents, using the diallel mating system. Emasculation and crossing of Bambara groundnut was effective when conducted on the same day, with the two procedures being carried out sequentially between 4:30 am and 9:00 am. This protocol generated a number of F1 seeds, with the most success being from crosses between 211-40-1 x N211-2, N212-8 x 211-40-1 and M09-3 x 211-82-1. These F1 seeds can be advanced to confirm whether they are true F1 or selfs. The most important production constraint of Bambara groundnut production is the lack of improved varieties, suggesting that further breeding is needed to enhance productivity. Bambara groundnut landraces need to be sorted using discrete morphological features before breeding for genetic enhancement. The SSR markers used in the study demonstrated their ability to distinguish the existing diversity among the Bambara groundnut genotypes, which could be useful for both germplasm conservation and for breeding. Genotypes that displayed outstanding performance in seed yield and biomass can be used as breeding lines for the genetic improvement of Bambara groundnut. Overall, the study generated valuable and novel Bambara groundnut genetic material, useful in the development of improved cultivars for large-scale production in sub-Saharan Africa. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2014.

Thesis (Ph. D.)--University of Wisconsin-Madison, 1997. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 294-303).

Thesis (MTech (Agriculture))--Cape Peninsula University of Technology, 2014. / Plants require nitrogen (N) to support desired production levels. Nitrogen fertilization strategy is a major consideration in field management with regard to achieving both economic and environmental objectives. For instance, in potato, insufficient N supply reduces tuber size and overall yield while excessive N supply can reduce tuber quality and increase environmental risk through nitrate (NO3-) leaching and nitrous oxide emission. Selection of an adequate N fertilizer application rate for crops is difficult, due to marked variations in soil N supply and crop N demand in both the field and over time. This research was conducted to characterise the ammonium transporter gene (AMT1) of Bambara groundnut and potato using molecular biology and bioinformatics methods. Nucleotide database sequences were used to design AMT1-specific primers which were used to amplify and sequence the core-region of the gene from Bambara groundnut and potato. Bioinformatics techniques were used to predict the structure and infer properties of the proteins. Nucleotide sequence alignment and phylogenetic analysis indicate that BgAMT1 and PoAMT1 are indeed from the AMT1 family, due to the clade and high similarity they respectively shared with other plant AMT1 genes. Amino acid sequence alignment showed that BgAMT1 is 92%, 89% and 87% similar to PvAMT1.1, GlycineAMT1 and LjAMT1.1 respectively, while PoAMT1 is 92%, 83% and 76% similar to LeAMT1.1, LjAMT1.1 and LeAMT1.2 respectively. BgAMT1 and PoAMT1 fragments were shown to correspond to the 5th - 10th transmembrane spanning-domains. Mutation of Bg W1A-L and S28A (for BgAMT1) and Po S70A (for PoAMT1) is predicted to enhance ammonium (NH4+) transport activity. Residues Bg D23 (for BgAMT1) and Po D16 (for PoAMT1) must be preserved otherwise NH4+ transport activity is inhibited. In all, BgAMT1 and PoAMT1 play a role in N uptake from the root while BgAMT1 may contribute more in different steps of rhizobia interaction. In an investigation of the correlation between AMT1 gene expression levels and leaf chlorophyll content index (CCI) with plant N status, potato plants were grown in a hydroponic greenhouse with 0.75 or 7.5 mM NO3- and 0.75 or 7.5 mM NH4+ as forms of N supply in a completely randomized design. Leaf CCI as measured by chlorophyll content meter, showed that an increase in N supply results in increased leaf CCI in response to both forms of N. Total RNA was isolated from leaf sampled at 28 days after treatment and expression level of the AMT1 gene was determined by reverse transcription-qPCR using a second set of primers designed for qPCR. The results showed that expression levels of AMT1 increased from 8.731 ± 2.606 when NO3- supply was high to 24.655 ± 2.93 when NO3- supply was low. However, there was no significant response in AMT1 expression levels to changes in NH4+. This result suggested that AMT1 transports NO3- less efficiently than NH4+, and thus more transport channels are required in the cell membrane when NO3- levels are low. Such variation in AMT1 expression levels are not necessary for NH4+ transport since the transport mechanism for NH4+ is efficient even at low NH4+ levels.