Sze, Wing Ho Angel. / "December 2010." / Thesis (M.Phil.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 90-112). / Abstracts in English and Chinese. / Thesis committee --- p.i / Statement --- p.ii / Acknowledgements --- p.iii / Abstract --- p.iv / 摘要 --- p.vi / Table of Contents --- p.viii / List of Tables --- p.xii / List of Figures --- p.xiii / List of Abbreviations --- p.xv / Chapter Chapter 1. --- General Introduction --- p.1 / Chapter Chapter 2. --- Literature Review / Chapter 2.1. --- Carotenoids in plants --- p.5 / Chapter 2.2 --- Carotenoid biosynthesis in plants --- p.7 / Chapter 2.3. --- Carotenoids in animals --- p.11 / Chapter 2.4. --- Vitamin A deficiency (VAD) --- p.13 / Chapter 2.5. --- Recommended requirement of vitamin A --- p.15 / Chapter 2.6. --- Bioavailability and bioconversion of dietary carotenoids --- p.17 / Chapter 2.7. --- Efforts to improve carotenoid contents in food crops --- p.19 / Chapter 2.8. --- Carotenoid catabolism --- p.20 / Chapter 2.9. --- Carotenoid cleavage dioxygenase (CCD) --- p.21 / Chapter 2.10. --- Carotenoid-derived phytohormones --- p.24 / Chapter 2.11. --- "CCD and carotenoid-derived colors, aromas and flavors" --- p.27 / Chapter Chapter 3. --- Hypothesis and Objectives --- p.35 / Chapter Chapter 4. --- Materials and methods / Chapter 4.1. --- General cloning and sequencing --- p.36 / Chapter 4.2. --- Extraction of RNA and DNase treatment --- p.36 / Chapter 4.3. --- Reverse transcription --- p.37 / Chapter 4.4. --- Real-time quantitative RT-PCR --- p.39 / Chapter 4.5. --- Cloning of OsCCD1 cDNA --- p.40 / Chapter 4.6. --- Bacterial in vivo assay of OsCCD 1 activity --- p.41 / Chapter 4.7. --- Construction of OsCCD1 RNAi constructs --- p.42 / Chapter 4.8. --- "Construction of ""Super-Golden"" rice constructs" --- p.46 / Chapter 4.8.1. --- "Construction of ""GluC-Y1-Nos"" cassette" --- p.46 / Chapter 4.8.2. --- "Construction of ""Gt1-TCN"" cassette" --- p.46 / Chapter 4.8.3. --- "Construction of""pGT-PCC""" --- p.47 / Chapter 4.8.4. --- "Construction of ""pGYGC""" --- p.47 / Chapter 4.9. --- Rice transformation --- p.54 / Chapter 4.10. --- Detection of transgene --- p.57 / Chapter 4.10.1. --- Southern blot --- p.57 / Chapter 4.10.2. --- HPLC analysis of carotenoids in seeds --- p.59 / Chapter Chapter 5. --- Results / Chapter 5.1. --- Expression profiles of carotenogenic genes in rice endosperms --- p.62 / Chapter 5.2. --- Expression of CCDs in developing rice seeds --- p.64 / Chapter 5.3. --- Features of OsCCD1 --- p.68 / Chapter 5.4. --- Characterization of OsCCD1-knock down transgenic rice --- p.72 / Chapter 5.5. --- "Construction of ""Super-Golden"" rice" --- p.78 / Chapter 5.6. --- Phenotypic characterization of PCC transgenic rice --- p.79 / Chapter 5.7. --- HPLC analysis on seed carotenoid content --- p.80 / Chapter Chapter 6. --- Discussion --- p.82 / Chapter Chapter 7. --- Conclusion --- p.89 / References --- p.90

Bacillus cereus is the most prevalent pathogenic Bacillus species found in foods, causing food spoilage and two types of toxin-mediated food poisoning known as the diarrhoeal and emetic syndromes. Other Bacillus species, particularly B. subtilis, B. licheniformis, B. brevis, B. pumilus and B. thuringensis, have also been recognised as food poisoning bacteria of increasing concern, with reports of outbreaks of diarrhoeal or emetic food poisoning. This study involved a systematic ecological investigation of Bacillus species isolated from rice products, commonly associated with Bacillus emetic food poisoning, using cultural and molecular methods. A centrifugation-plating method, more sensitive than the conventional spread plating method, was developed and used to determine the occurrence and biodiversity of Bacillus species in rice, a well known source of B. cereus. Eight different Bacillus species, B. cereus/B. thuringiensis, B. mycoides, B. subtilis/B. mojavensis, B. licheniformis, B. pumilus, B. sphaericus/B. fusiformis and B. megaterium, as well as Paenibacillus species, identified by partial rDNA sequencing, were isolated from raw (uncooked) and cooked rice products. The diversity of the isolates at the subspecies (strain) level was investigated using the RAPD-PCR typing technique, which proved to be useful for differentiating strains of bacilli, revealing broad diversity among the strains. Generally, different genotypes were found in raw and cooked rice, with some isolates of the same RAPD pattern found in both raw and cooked rice. The toxigenic potential of Bacillus isolates were also determined by molecular and immunological analysis as well as an MEKC method, developed in this study for quantitative analysis of the emetic toxin, cereulide. The results revealed that most isolates from the B. cereus group were potentially or actually toxigenic and some isolates were able to produce both diarrhoeal and emetic toxins. Other Bacillus species outside the B. cereus group were also shown to produce cereulide.

High-temperature processing of rice needs close attention due to the susceptibility of rice grains to fissures. The present study was carried out to redress the lack of information on the quality of rice dried at high-temperatures using a range of drying air temperatures from 160 - 200??C and grain moisture contents varying from 27 to 33%wb. A laboratory type high temperature dryer-oven was developed and constructed, and the performance was compared with commercial fluidized-bed and spouted-bed dryers. The new column type treatment plant, targeted at small-scale rice farmers was designed to reduce milling breakages was tested for high-temperature treatments. Short term drying (160 ??? 180 seconds) of high moisture rough rice at high-temperatures such as 160 - 200??C increased head rice yield by 5 - 8% in long grain rice and 7 - 11% in medium grain rice. The head rice yield increase achieved was very close to the highest potential head rice recovery possible for a given sample. The head rice yield increase was mainly due to a hardened surface layer of the rice kernel, formed by two effects, a surface fusion and surface gelatinization during high-temperature treatment. This stress protection layer is only effective for a short period (1 - 2 minutes) at high temperatures. Tempering of treated grains, either by storing in gunny bags or rapid cooling, can secure the grains to some extent from grain breakage. The highest head rice yield increase was obtained by ceasing the high-temperature effect at the grain moisture level of 24 - 25%wb. The colour and appearance of high-temperature treated grains were closer to those of untreated grains with the toughness closer to that of parboiled rice. The setback values of high-temperature treated rice measured by RVA, which is a preferred character by consumers, were closer to aged rice. High-temperature treatments did not affect the cooking qualities except a slight increase in water absorption. The alterations in the grain due to high-temperature treatment are limited to only for 8 - 9% of the total volume (mainly outer region) of the rice grain, preserving more than 90% of the grain with raw-rice quality. Structural changes such as complexing of amylose ??? lipid, amylose -protein and denaturation of protein play a dominant role on quality changes than gelatinization. A new method introduced to measure the degree of gelatinization of pre-gelatinized rice, using hot paste viscosity by rapid visco analyser (RVA), was successful. The peak viscosity parameter in the RVA was more suitable for measuring the chemical changes in high-temperature treated rice. Spouted-bed drying technology is not suitable for high-temperature treatment due to the unfavourable conditions for the formation of a hardened layer under intermittent heating and cooling. Fluidized-bed dryers could be used for high-temperature drying, but is not cost effective for the small-scale farmer level. The novel type treatment plant was successful in reducing the amount of broken grains to almost zero, increasing the head rice yield by 50 - 120kg per 1000kg of rough rice. It was also effective as a germination arrester, inhibiting the germination ability within a very short period such as 30 - 60 seconds. This equipment is more effective as a treatment Plant as it reduces moisture by only 1.5 - 2.0% at highest head rice yield recovery. An empirical model was successfully established (R2 = 0.99) for grain moisture content (db) and drying temperature during high-temperature processing. In model validation process, a good agreement was found between predicted and experimental data. The modelling between head rice yield and high-temperature drying was unsuccessful (R2 = 0.89) mainly due the interference from other factors such as initial moisture stress due to re-wetting and uncontrolled post treatment drying environment conditions. The study revealed some breakthrough for the rice industry in addition to its quantitative evaluation of increase in head rice yield. 1. Ability to produce grains with twice the toughness of milled untreated rice, without losing colour and appearance. 2. Fissured grains, previously weakened due to moisture-stress (considered as a loss), can be successfully recovered by treating this high-temperature technique. Currently there is no method available to increase the head rice yield of this type of fissured grains except parboiling, which is not widely accepted among consumers. 3. Drying at 200??C drying temperature completely destroyed the viability of seeds within 40 -60 seconds, hence providing a remedy for germination problems in wet harvests. 4. Since high-temperature drying needs wet rough rice, early harvesting can be done which will reduce shattering losses. This enable the farmers to use the field for an inter-seasonal crop which can utilise higher residual soil moisture in the paddy fields compared to other crops.

Graduation date: 1993

Graduation date: 1992

Genetic resource enhancement is the foundation of any good breeding program. Landraces from West Africa, interspecifics between Oryza sativa and Oryza glaberrima and improved lines from the West African Rice Development Association and other research centers were introduced to the Beaumont Rice Research center for in situ evaluation and characterization. Beside the introduction of seeds, milled samples were also introduced for grain chemistry analysis. Field evaluation combined with physicochemical and molecular characterization revealed unique characteristics among African germplasm. New rice for Africa (NERICA) lines performed well in the USA environment. Varieties like Nerica 2, Nerica 3, Nerica 4, and Nerica 5 need more attention because of their superior performance in yield and grain quality. Landraces did not perform well due to their height and late maturity and their resulting problems with lodging. The rapid visco analyzer RVA profiles showed that the cultivar Jaya has unusually strong paste viscosity features. Comparing West Africa samples grown in Cote d’Ivoire with those grown in Texas, parameters like AA, ASV, Hot, Cool, and CT were not stongly affected by the environment. According to the Stbk value, cultivars grown in Cote d’Ivoire will cook softer than when they were grown in Texas. The lack of the environmental effect is somewhat surprising considering the difference in latitude, soil types, weather patterns, and management practices between the two locations. Apparent amylose is a key element to characterize a rice cultivar; however certain varieties like Cocodrie and Dixiebelle have similar apparent amylose content but dramatically different functional qualities. A population derived from Cocodrie and Dixiebelle was developed for genotypic and phenotypic analysis of grain chemistry traits that affect functionality. It was concluded that the amount of soluble amylose in the grain had a significant effect on flour pasting properties, even when total apparent amylose content did not vary. Marker association studies revealed that the Waxy microsatellite and the Waxy exon 10 SNP markers were associated with soluble amylose content and RVA characteristics. These markers will speed up the development of new rice cultivars with desirable quality characteristics in West Africa and in the USA.

Thesis (M. Phil.)--University of Hong Kong, 2001. / Includes bibliographical references (leaves 104-107).

published_or_final_version / abstract / toc / Botany / Master / Master of Philosophy

published_or_final_version / Botany / Master / Master of Philosophy

published_or_final_version / Zoology / Master / Master of Philosophy