Yeung Chi-wang. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (leaves 128-144). / Abstracts in English and Chinese. / Abstract (in English) --- p.i / Abstract (in Chinese) --- p.iv / Acknowledgement --- p.vi / Contents --- p.vii / List of Figures --- p.xi / List of Tables --- p.xiii / Chapter Chapter 1 --- Introduction --- p.1 / Chapter Chapter 2 --- Literature review --- p.3 / Chapter 2.1 --- Nutritional facts of fish --- p.3 / Chapter 2.2 --- Aroma of fish --- p.5 / Chapter 2.2.1 --- Carbonyls and alcohols --- p.6 / Chapter 2.2.2 --- Sulphur-containing compounds --- p.7 / Chapter 2.2.3 --- Bromophenols --- p.9 / Chapter 2.2.4 --- Hydrocarbons --- p.9 / Chapter 2.2.5 --- Off flavor in fish --- p.9 / Chapter 2.2.6 --- Autoxidation of fish meat --- p.10 / Chapter 2.2.7 --- (Z)-4-heptenal in cooked and stored fish --- p.10 / Chapter 2.2.8 --- Volatile acids --- p.11 / Chapter 2.3 --- Salted-dried fish in Hong Kong --- p.11 / Chapter 2.3.1 --- Salted-dried fish used in this study --- p.13 / Chapter 2.3.2 --- Salting methods of the salted-dried fish used in this study --- p.14 / Chapter 2.3.3 --- Salting method used in Tai O --- p.15 / Chapter 2.4 --- Aroma analysis --- p.19 / Chapter 2.4.1 --- Extraction methods --- p.19 / Chapter 2.4.1.1 --- Steam distillation methods --- p.20 / Chapter 2.4.1.2 --- Solvent extraction methods --- p.22 / Chapter 2.4.1.3 --- Headspace methods --- p.22 / Chapter 2.4.2 --- Screening of important aroma contributing volatile compounds --- p.23 / Chapter 2.5 --- Overview --- p.26 / Chapter Chapter 3 --- Method Development --- p.28 / Chapter 3.1 --- Introduction --- p.28 / Chapter 3.2 --- Methodology --- p.29 / Chapter 3.2.1 --- Reproducibility of injection mode --- p.29 / Chapter 3.2.2 --- Optimization of the sample preparation procedure --- p.29 / Chapter 3.2.3 --- Gas chromatography-mass spectrometry coupled with cooled injection system (GC-MS-CIS) --- p.30 / Chapter 3.3 --- Results and discussion --- p.31 / Chapter 3.3.1 --- Reproducibility of the cooled injection system --- p.31 / Chapter 3.3.2 --- Efficiency of different injection modes --- p.33 / Chapter 3.3.3 --- Optimal equilibrium Time --- p.33 / Chapter 3.3.4 --- Conclusion --- p.37 / Chapter Chapter 4 --- Volatile compounds in the headspace of salted-dried fish --- p.38 / Chapter 4.1 --- Introduction --- p.38 / Chapter 4.2 --- Materials and Methods --- p.39 / Chapter 4.2.1 --- Sample preparation --- p.39 / Chapter 4.2.2 --- Headspace analysis and gas chromatography-mass spectrometry (GC-MS) --- p.42 / Chapter 4.2.3 --- "Identification, quantification and odor activity values (OAV) of compounds" --- p.43 / Chapter 4.2.4 --- Statistical analysis --- p.44 / Chapter 4.3 --- Results and discussion --- p.45 / Chapter 4.3.1 --- Headspace profiles of three salted-dried fishes in Hong Kong --- p.45 / Chapter 4.3.1.1 --- Aldehydes and alcohols --- p.63 / Chapter 4.3.1.2 --- Hydrocarbons and ketones --- p.66 / Chapter 4.3.1.3 --- Nitrogen- (N-)containing and sulfur- (S-)containing compounds --- p.68 / Chapter 4.3.1.4 --- "Esters, furans and pyrazines" --- p.72 / Chapter 4.3.1.5 --- "Acids, pyrroles and pyridine" --- p.73 / Chapter 4.3.1.6 --- Important aroma contributing compounds in salted-dried fish --- p.74 / Chapter 4.3.2 --- Influence of steaming on the salted-dried fish headspace --- p.75 / Chapter 4.3.3 --- Difference in the headspace of salted-dried fish purchased between the first and second year --- p.76 / Chapter 4.3.4 --- Influence of salting methods on the salted-dried fish aroma --- p.76 / Chapter 4.3.5 --- Difference between salted-dried fish purchased at Sai Wan and Tai O --- p.78 / Chapter 4.3.6 --- Difference between salted-dried fish produced from difference fish species --- p.78 / Chapter 4.4 --- Conclusion --- p.79 / Chapter Chapter 5 --- Aroma active compounds in salted-dried fish --- p.81 / Chapter 5.1 --- Introduction --- p.81 / Chapter 5.2 --- Materials and Methods --- p.82 / Chapter 5.2.1 --- Sample preparation --- p.82 / Chapter 5.2.2 --- Gas chromatography static headspace analysis and olfactometry GC-SHA-O and aroma extract dilution analysis (AEDA) --- p.84 / Chapter 5.2.3 --- Compound identification --- p.85 / Chapter 5.2.4 --- Calculation of flavor dilution (FD) factor --- p.85 / Chapter 5.3 --- Results and discussion --- p.86 / Chapter 5.3.1 --- Aroma active compounds in salted-dried fish --- p.86 / Chapter 5.3.1.1 --- Strong and Potent aromas --- p.87 / Chapter 5.3.1.2 --- Roasted aromatic aromas --- p.94 / Chapter 5.3.1.3 --- Floral aromas --- p.95 / Chapter 5.3.1.4 --- Vegetative aromas --- p.96 / Chapter 5.3.1.5 --- Penetrating aromas --- p.97 / Chapter 5.3.1.6 --- Common aromas --- p.98 / Chapter 5.3.2 --- Characteristic of aroma active compounds between steamed and non-steamed salted-dried fish --- p.99 / Chapter 5.3.3 --- Differences in aroma active compounds between regular and delayed salted-dried fish --- p.100 / Chapter 5.3.4 --- Characteristic aroma of different species of salted-dried fish --- p.105 / Chapter 5.3.5 --- Characteristic aroma of salted-dried fish purchased at Sai Wan and Tai O --- p.108 / Chapter 5.3.6 --- Characteristic aroma of salted-dried fish purchased in 2001 and 2002 --- p.108 / Chapter 5.4 --- Conclusion --- p.108 / Chapter Chapter 6 --- Important volatile compounds in salted-dried fish --- p.112 / Chapter 6.1 --- Comparison between OAV and SHA-O --- p.112 / Chapter 6.2 --- Overall conclusion --- p.114 / Chapter 6.2.1 --- Effects of steaming on salted-dried fish aroma --- p.114 / Chapter 6.2.2 --- Effects of salting methods on salted-dried fish aroma --- p.117 / Chapter 6.2.3 --- Characteristics aroma of salted-dried fish prepared from different fish species --- p.120 / Chapter 6.2.4 --- Characteristics aroma of salted-dried fish purchased from different locations --- p.120 / Chapter 6.2.5 --- Characteristics aroma of salted-dried fish purchased from different periods --- p.125 / References --- p.128 / Appendix --- p.145

The effects and desirability of utilizing dried whey in pie crust, muffins, and beef gravies were studied using taste panel evaluations and objective testings. In pas try the addition of whey caused significant changes. As the whey level increased to 10 percent of the flour weight, the crust became browner during baking and the shortometer recorded an increase in tenderness. The taste panel noted as whey levels increased to 10 percent and above that the color became yellow instead of creamy white; the flavor became undesirable; and pastry became less tender and flaky. Whey significantly increased the desirability of muffins by enhancing the golden brown color, producing a more desirable flavor and increasing the tenderness of the muffins. Whey enhanced the flavor of fresh gravies. The consistency and mouth feel rated undesirable in milk gravies when whey was added. However it was more acceptable in gravies using water as the liquid. High whey levels prevented excessive retrogradation, but had adverse flavor effects.

In Western Australia dried meat baits containing 1080 are used extensively by agricultural and conservation organisations to control foxes and dingoes for the protection of agricultural production and native fauna. Field trials were conducted to assess 1080 loss from dried meat baits and this required the analysis of over five hundred baits. Because of this large number of baits it was essential to have a simple and efficient 1080 extraction procedure and method of 1080 analysis. In this study three methods of 1080 extraction and the new bioassay method for 1080 analysis were investigated. A simple and cost-effective 1080 extraction method using water with a 98% 1080 recovery rate was developed and modifications to the bioassay method were made.Factory-produced 1080 dried meat baits were laid in the field during different seasons at four locations in Western Australia, samples were collected over time and analysed for 1080 content using the bioassay. Rainfall was recorded and temperature data was collected for each site. Baits were exposed to the elements but were placed in mesh or wire cages to restrict invertebrate attack and prevent removal by vertebrates. Some baits were placed on the surface and others were buried. Initially 1080 loss from baits from all 4 sites was minimal, ranging from 0 - 21% at day 7 - 9. Further loss was gradual even when rainfall was recorded. Generally baits had to be exposed to at least 50 mm of rain before 1080 loss increased to 50%. At some sites baits continued to remain toxic to foxes even after long exposure. The mean 1080 content of baits from the Carnarvon site at day 226 was 2.0 mg (55% of the mean 1080 content of baits at day zero) with 137 mm of rainfall recorded for that period. Loss of 1080 from baits buried occurred at a faster rate than from baits placed on the surface during the same time period. By day 14 no 1080 was ++ / detected in the buried baits compared to the 68% detected in the surface baits. Under certain conditions 1080 loss from baits was minimal. Levels of 1080 in baits from Nangeen Hill remained fairly constant during the months of September to December 1995, and again during February to April 1996.Gastrolobium plant tissue and soil samples from the southwest of Western Australia were investigated for the presence of 1080 degrading microorganisms. Microbes were isolated and individually tested in solution containing 1080 as the sole carbon source. Isolates which showed 1080 degrading ability were further tested for their degrading efficiency in McClung carbon-free solution with added 1080 as the sole source of carbon and in factory 1080 waste solution, at 1080 concentrations of 20 and 200 mM. The effect of temperature on their rate of degradation was also examined. Thirteen isolates (7 fungi and 6 bacteria) showing varying degrees of 1080 degrading ability were obtained. Rates of 1080 degradation varied among isolates but were highest in the factory waste solution at the 20 mM concentration and in the McClung solution, where 1080 was the sole source of carbon, at the higher concentration of 200 mM. The most efficient isolates OSK and 10H (both Pseudomonas species) degraded all the 1080 present in sterile factory waste solution up to 20 mM 1080 concentration in 4 days and the isolate 1AF (Fusarium oxysporum) degraded 93% of 200 mM 1080 in the McClung solution in 9 days. The optimum temperatures for 1080 degradation were 30 degrees celsius and fluctuating ambient temperatures of 15 28 degrees celsius.

Bio fuels are made from an extensive selection of fuels derived from biomass, including wood waste, agricultural wastes, and alcohol fuels. As a result of increased energy requirements, raised oil prices, and concern over greenhouse gas emissions from fossil fuels, bio fuels are acquiring increased public and scientific attention. The ethanol industry is booming and during the past several years, there has been an increase in demand for fuel ethanol and use of its co-products. To increase potential revenues from ethanol processing and its utilization, extensive research is proceeding in this field. In Western Canada, wheat is the primary raw material used in the production of ethanol by fermentation and distillers dried grains with solubles (DDGS) are one of the major co-products produced during this process. At present, the DDGS are generally sold as animal feed stock but with some alteration they could be used in other useful areas.<p> Densification of biomass and use of it for fuel like wood pellets, hay briquettes, etc. have been studied for many years and have also been commercialized. In this thesis, pellets made from distillers dried grains have been investigated. DDGS were obtained from Noramera Bioenergy Corp. and Terra Grain Fuels Ltd. Before transforming them into pellets, they were characterized on the basis of physical and chemical properties. A California pilot-scale mill (with and without steam conditioning) was used for pelleting the distillers grains with solubles.<p> A full factorial design with two levels of moisture content (i.e., 14 and 15.5% (w.b.)), hammer mill screen size (i.e., 3.2 and 4.8 mm) and temperature (i.e., 90 and 100°C) was used to determine the effects of these three factors on the pellet properties made from Noramera Bioenergy Corp., without steam conditioning. Different levels of moisture content were used for the pellets made from Terra Grain Fuels Ltd. (i.e., 11.5 and 13.09% (w.b.)), with steam conditioning. The initial moisture contents of the DDGS were 12.5 and 13.75% (w.b.) from Noramera and Terra Grain, respectively. The moisture content of DDGS grinds ranged from 11.6 to 12.03% (w.b.) for the Noramera samples, and from 11.5 to 13.09% (w.b.) for Terra Grain DDGS. The moisture content decreased with a decrease in the hammer mill screen size.<p> The use of a smaller screen size achieved an increase in both the bulk and particle densities of the DDGS. The coefficient of internal friction was almost the same for both samples but cohesion was higher in Noramera samples (8.534 kPa). The DDGS obtained from Noramera Bioenergy Corp. contained dry matter (91.40%), crude fibre (4.98%), crude protein (37.41%), cellulose (10.75%), hemi-cellulose (21.04%), lignin (10.50%), starch (3.84%), fat (4.52%) and ash (5.16%); whereas the samples obtained from Terra Grain Fuels contained dry matter (87.69%), crude fibre (7.33%), crude protein (32.43%), cellulose (10.81%), hemi-cellulose (27.45%), lignin (4.37%), starch (4.18%), fat (6.37%) and ash (4.50%).<p> The combustion energy of the Noramera samples was 19.45 MJ/kg at a moisture content of 8.6% (w.b.) whereas the combustion energy of Terra Grain samples was 18.54 MJ/kg at 12.31% (w.b.) moisture content.<p> The durability of the pellets increased as the screen size decreased which is likely due to the fact that a smaller screen size produces more fine particles. This fill voids in the pellets and, hence, makes them more durable.<p> The length of the pellets produced from Noramera DDGS increased with a decrease in moisture content possibly because pellets formed at higher moisture content absorb less moisture. Therefore, the length does not increase as much. Lateral expansion occurred most with higher temperature and lower moisture content and with lower temperature and higher moisture content. The length to diameter ratio of the pellets followed the same trend as the change in pellet length. The length of the pellets produced from Terra Grain also increased with a decrease in moisture content. The lateral expansion increased with increase in screen size and moisture content and also, with decrease in moisture content and increase in temperature. The length to diameter ratio increased with decrease in screen size and moisture content, similar to the change in pellet length. The highest bulk density of Noramera pellets resulted from smaller screen size and lower moisture. The particle density increased with a decrease in screen size and an increase in moisture content. The highest bulk density of Terra Grain pellets occurred with an increase in temperature and decrease in moisture content. The highest particle density occurred with an increase in temperature and decrease in screen size.<p> The pellet hardness increased with a decrease in moisture content and screen size did not have any significant effect. The Terra Grain pellets were harder because they were subjected to steam conditioning. Steam conditioning helps to increase the hardness.<p> The pellet durability increased with a decrease in screen size and increase in moisture content. The steam conditioning also caused the higher durability in the Terra Grain pellets. In terms of moisture absorption, the only significant factor was moisture content. Pellets with lower moisture content absorbed more moisture.<p> The ash content values of pellets were higher in Noramera samples than in Terra Grain samples because of high moisture content in Noramera samples. The combustion energy of the Noramera pellets was higher than the Terra Grain pellets because of the high percentage of dry matter and lignin present in Noramera samples. The emission results for both the sample pellets were similar. When the DDGS pellets were compared to wood pellets, emission of nitrous oxide was lower for wood whereas, carbon dioxide was higher.

The main objective of this project was to investigate the effects of the type of dried distillers grains with solubles (wheat DDGS, corn DDGS, and blend DDGS (eg. wheat:corn = 70:30)) and bio-ethanol plant origin on the nutrient variation and availability in ruminants. In addition, DDGS products were studied as opposed to their parental grains. The project was divided into the several following studies. In Study 1, we studied the nutritive value of DDGS products in terms of (1) chemical profiles, (2) protein and carbohydrate sub-fractions associated with different degradation rates, and (3) digestible component nutrients and energy values using the NRC 2001-chemical approach and the in situ assay-biological approach. Also, we tested the validity of acid detergent insoluble crude protein (ADICP) and acid detergent lignin (ADL) to predict the potential degradability of DDGS. Due to starch fermentation in the ethanol process, the chemical components in DDGS became approximately threefold more concentrated than in feedstock grains. Slowly degraded protein (PB3) and unavailable protein (PC) increased in DDGS, indicating a decrease in the overall protein degradability in the rumen. Intermediately degraded protein (PB2) was higher for corn DDGS than for wheat DDGS and blend DDGS (54.2 vs. 27.7 vs. 30.8 %CP), while PB3 was higher for wheat DDGS and blend DDGS (29.9 vs. 51.2 vs. 53.2 %CP). Mainly as a result of differing heat conditions, PC differed significantly between wheat DDGS originated at different bio-ethanol plants (0.7 vs. 7.6 %CP). The prediction of truly digestible CP (tdCP) and NDF (tdNDF) differed between the NRC 2001-chemical approach and the in situ assay-biological approach; however, both approaches reported similar energy values. These values were the highest for corn DDGS (DE3X: 3.9 Mcal kg-1), followed by blend DDGS (DE3X: 3.6 Mcal kg-1), and wheat DDGS (DE3X: 3.4 Mcal kg-1). Corn DDGS was superior to corn, wheat DDGS was similar to wheat and corn, and blend DDGS was similar to corn. No significant differences in energy values were reported between bio-ethanol plants. ADICP was not an accurate indicator of the potential degradability of protein in DDGS samples, while ADL seemed to be an acceptable indicator of the potential degradability of DM (r = -0.87; P<0.01), CP (r = -0.89; P<0.01), and NDF (r = -0.82; P<0.01) in wheat DDGS samples incubated in rumen during 48 h.<p> In Study 2, we studied the ruminal and intestinal digestion profiles and the hourly effective rumen degradation ratios between nitrogen (N) and energy. The results showed a reduction in the effective degradability of DM (EDDM), OM (EDOM) and CP (EDCP) of wheat DDGS relative to wheat; however, corn DDGS remained the same as corn. The effective degradability of NDF (EDNDF) did not vary between the DDGS samples and feedstock grains. Among DDGS types, EDDM ranged from 52.4 to 57.7 %, EDOM from 46.4 to 53.5 %DM, and EDCP from 34.0 to 45.6 %CP, being higher as the proportion of wheat in feedstock increased. No significant differences in EDDM, EDOM, EDCP and EDNDF for wheat DDGS were detected between the different bio-ethanol plants. The hourly effective degradability ratios between N and energy indicated a potential excess of N in rumen when DDGS samples were evaluated as single ingredient. This excess increased as the proportion of wheat in feedstock increased. Estimated intestinal digestibility of rumen bypass protein (IDP) was similar between wheat and wheat DDGS, but higher in corn DDGS than in corn. Blend DDGS had the highest IDP (93.9 %RUP). Due to the significantly different PC sub-fraction found in wheat DDGS originated at the different bio-ethanol plants, a large but numerical difference was detected in IDP (89.4 vs. 75.9 %RUP).<p> In Study 3, we used both the DVE/OEB System and the NRC 2001 Model to reveal the metabolic characteristics of DDGS protein and predict the protein supply to dairy cattle. The two models showed higher protein values (DVE or MP) for DDGS samples than for feedstock grains. The higher IDP for blend DDGS largely contributed to the higher protein value relative to wheat DDGS and corn DDGS (MP: 277 vs. 242 vs. 250 g kg-1 DM). Similarly, protein values differed significantly between the bio-ethanol plants mainly as a result of the numerical but large difference in IDP (MP: 272 vs. 223 g kg-1 DM). According to the two models, the degraded protein balance for DDGS products was higher than in the parental grains. Wheat DDGS showed the highest potential N excess (DBPNRC: 78 g kg-1 DM). For corn DDGS, however, the DVE/OEB System suggested a potential N excess (11 g kg-1 DM) while the NRC 2001 Model exhibited a potential N deficiency (-12 g kg-1 DM). The degraded protein balance for wheat DDGS was similar between the different bio-ethanol plants.<p> In conclusion, the chemical and biological characteristics of DDGS varied among types and between wheat DDGS samples manufactured at the different bio-ethanol plants. Thus, it is inappropriate to assume fixed values for the nutritive value of DDGS without considering factors such as type of grain used and bio-ethanol plant origin. Further research with higher number of samples will help to clarify the use of the chemical profile to predict energy values and the potential degradability of DDGS.

EVALUATION AND DETERMINATION OF THE SENSITIVITY AND SPECIFICITY OF A Treponema pallidum DRIED BLOOD SPOT (DBS) METHOD FOR SEROLOGIC DIAGNOSIS OF SYPHILIS Background: Syphilis is a sexually transmitted infection (STI) caused by Treponema pallidum subspecies pallidum. Syphilis is known as the "great imitator" due to the similarity of clinical signs and symptoms to other infectious diseases. The primary diagnosis of syphilis relies on clinical findings, including the examination of treponemal lesions, and/or serologic tests. Serologic tests are divided into nontreponemal and treponemal tests. Nontreponemal tests are useful for screening, while treponemal tests are used as confirmatory tests. Methods: A total of 200 serum and DBS specimens collected from patients at the Los Angeles Municipal Sexually Transmitted Disease Clinics were tested by the DBS and enzyme immunoassay (EIA) methods. These samples were sent to the Syphilis Diagnostics Laboratory, Centers for Disease Control and Prevention (CDC) in Atlanta, Georgia for testing. Samples were blindly evaluated by the TREP-SPOTTM DBS and the TREP- SURETM EIA methods for the detection of anti-treponemal IgG- and IgM-class antibodies. Results: The sensitivity of the DBS method was 83% (95% CI, 73.89 - 89.50) and specificity was 100% (95% CI, 95.39 - 100)). The positive predictive value and negative predictive values were 100% (95% CI, 94.48 - 100) and 85% (95% CI, 77.43 - 91.0), respectively. The efficiency of the DBS method was 91.5%. The kappa value for the agreement between the DBS method and EIA assay was 0.83 (95% CI, 0.754 - 0.906). The correlation coefficient (r2) between the anti-treponemal antibody assay results obtained from DBS and serum samples was 0.94. Conclusion: DBS is an optimal choice to be used as a screening tool for the detection of anti-treponemal antibodies for the diagnosis of syphilis. The detection of anti-treponemal antibodies (TREP-SPOTTM DBS EIA) compared favorably to the results of serum-base assay (TREP-SURETM EIA), with an overall concordance of 91.5%. Dried blood spots are technically easier to obtain and are suitable blood samples for primary health care centers.

Bio fuels are made from an extensive selection of fuels derived from biomass, including wood waste, agricultural wastes, and alcohol fuels. As a result of increased energy requirements, raised oil prices, and concern over greenhouse gas emissions from fossil fuels, bio fuels are acquiring increased public and scientific attention. The ethanol industry is booming and during the past several years, there has been an increase in demand for fuel ethanol and use of its co-products. To increase potential revenues from ethanol processing and its utilization, extensive research is proceeding in this field. In Western Canada, wheat is the primary raw material used in the production of ethanol by fermentation and distillers dried grains with solubles (DDGS) are one of the major co-products produced during this process. At present, the DDGS are generally sold as animal feed stock but with some alteration they could be used in other useful areas.<p> Densification of biomass and use of it for fuel like wood pellets, hay briquettes, etc. have been studied for many years and have also been commercialized. In this thesis, pellets made from distillers dried grains have been investigated. DDGS were obtained from Noramera Bioenergy Corp. and Terra Grain Fuels Ltd. Before transforming them into pellets, they were characterized on the basis of physical and chemical properties. A California pilot-scale mill (with and without steam conditioning) was used for pelleting the distillers grains with solubles.<p> A full factorial design with two levels of moisture content (i.e., 14 and 15.5% (w.b.)), hammer mill screen size (i.e., 3.2 and 4.8 mm) and temperature (i.e., 90 and 100°C) was used to determine the effects of these three factors on the pellet properties made from Noramera Bioenergy Corp., without steam conditioning. Different levels of moisture content were used for the pellets made from Terra Grain Fuels Ltd. (i.e., 11.5 and 13.09% (w.b.)), with steam conditioning. The initial moisture contents of the DDGS were 12.5 and 13.75% (w.b.) from Noramera and Terra Grain, respectively. The moisture content of DDGS grinds ranged from 11.6 to 12.03% (w.b.) for the Noramera samples, and from 11.5 to 13.09% (w.b.) for Terra Grain DDGS. The moisture content decreased with a decrease in the hammer mill screen size.<p> The use of a smaller screen size achieved an increase in both the bulk and particle densities of the DDGS. The coefficient of internal friction was almost the same for both samples but cohesion was higher in Noramera samples (8.534 kPa). The DDGS obtained from Noramera Bioenergy Corp. contained dry matter (91.40%), crude fibre (4.98%), crude protein (37.41%), cellulose (10.75%), hemi-cellulose (21.04%), lignin (10.50%), starch (3.84%), fat (4.52%) and ash (5.16%); whereas the samples obtained from Terra Grain Fuels contained dry matter (87.69%), crude fibre (7.33%), crude protein (32.43%), cellulose (10.81%), hemi-cellulose (27.45%), lignin (4.37%), starch (4.18%), fat (6.37%) and ash (4.50%).<p> The combustion energy of the Noramera samples was 19.45 MJ/kg at a moisture content of 8.6% (w.b.) whereas the combustion energy of Terra Grain samples was 18.54 MJ/kg at 12.31% (w.b.) moisture content.<p> The durability of the pellets increased as the screen size decreased which is likely due to the fact that a smaller screen size produces more fine particles. This fill voids in the pellets and, hence, makes them more durable.<p> The length of the pellets produced from Noramera DDGS increased with a decrease in moisture content possibly because pellets formed at higher moisture content absorb less moisture. Therefore, the length does not increase as much. Lateral expansion occurred most with higher temperature and lower moisture content and with lower temperature and higher moisture content. The length to diameter ratio of the pellets followed the same trend as the change in pellet length. The length of the pellets produced from Terra Grain also increased with a decrease in moisture content. The lateral expansion increased with increase in screen size and moisture content and also, with decrease in moisture content and increase in temperature. The length to diameter ratio increased with decrease in screen size and moisture content, similar to the change in pellet length. The highest bulk density of Noramera pellets resulted from smaller screen size and lower moisture. The particle density increased with a decrease in screen size and an increase in moisture content. The highest bulk density of Terra Grain pellets occurred with an increase in temperature and decrease in moisture content. The highest particle density occurred with an increase in temperature and decrease in screen size.<p> The pellet hardness increased with a decrease in moisture content and screen size did not have any significant effect. The Terra Grain pellets were harder because they were subjected to steam conditioning. Steam conditioning helps to increase the hardness.<p> The pellet durability increased with a decrease in screen size and increase in moisture content. The steam conditioning also caused the higher durability in the Terra Grain pellets. In terms of moisture absorption, the only significant factor was moisture content. Pellets with lower moisture content absorbed more moisture.<p> The ash content values of pellets were higher in Noramera samples than in Terra Grain samples because of high moisture content in Noramera samples. The combustion energy of the Noramera pellets was higher than the Terra Grain pellets because of the high percentage of dry matter and lignin present in Noramera samples. The emission results for both the sample pellets were similar. When the DDGS pellets were compared to wood pellets, emission of nitrous oxide was lower for wood whereas, carbon dioxide was higher.

The main objective of this project was to investigate the effects of the type of dried distillers grains with solubles (wheat DDGS, corn DDGS, and blend DDGS (eg. wheat:corn = 70:30)) and bio-ethanol plant origin on the nutrient variation and availability in ruminants. In addition, DDGS products were studied as opposed to their parental grains. The project was divided into the several following studies. In Study 1, we studied the nutritive value of DDGS products in terms of (1) chemical profiles, (2) protein and carbohydrate sub-fractions associated with different degradation rates, and (3) digestible component nutrients and energy values using the NRC 2001-chemical approach and the in situ assay-biological approach. Also, we tested the validity of acid detergent insoluble crude protein (ADICP) and acid detergent lignin (ADL) to predict the potential degradability of DDGS. Due to starch fermentation in the ethanol process, the chemical components in DDGS became approximately threefold more concentrated than in feedstock grains. Slowly degraded protein (PB3) and unavailable protein (PC) increased in DDGS, indicating a decrease in the overall protein degradability in the rumen. Intermediately degraded protein (PB2) was higher for corn DDGS than for wheat DDGS and blend DDGS (54.2 vs. 27.7 vs. 30.8 %CP), while PB3 was higher for wheat DDGS and blend DDGS (29.9 vs. 51.2 vs. 53.2 %CP). Mainly as a result of differing heat conditions, PC differed significantly between wheat DDGS originated at different bio-ethanol plants (0.7 vs. 7.6 %CP). The prediction of truly digestible CP (tdCP) and NDF (tdNDF) differed between the NRC 2001-chemical approach and the in situ assay-biological approach; however, both approaches reported similar energy values. These values were the highest for corn DDGS (DE3X: 3.9 Mcal kg-1), followed by blend DDGS (DE3X: 3.6 Mcal kg-1), and wheat DDGS (DE3X: 3.4 Mcal kg-1). Corn DDGS was superior to corn, wheat DDGS was similar to wheat and corn, and blend DDGS was similar to corn. No significant differences in energy values were reported between bio-ethanol plants. ADICP was not an accurate indicator of the potential degradability of protein in DDGS samples, while ADL seemed to be an acceptable indicator of the potential degradability of DM (r = -0.87; P<0.01), CP (r = -0.89; P<0.01), and NDF (r = -0.82; P<0.01) in wheat DDGS samples incubated in rumen during 48 h.<p> In Study 2, we studied the ruminal and intestinal digestion profiles and the hourly effective rumen degradation ratios between nitrogen (N) and energy. The results showed a reduction in the effective degradability of DM (EDDM), OM (EDOM) and CP (EDCP) of wheat DDGS relative to wheat; however, corn DDGS remained the same as corn. The effective degradability of NDF (EDNDF) did not vary between the DDGS samples and feedstock grains. Among DDGS types, EDDM ranged from 52.4 to 57.7 %, EDOM from 46.4 to 53.5 %DM, and EDCP from 34.0 to 45.6 %CP, being higher as the proportion of wheat in feedstock increased. No significant differences in EDDM, EDOM, EDCP and EDNDF for wheat DDGS were detected between the different bio-ethanol plants. The hourly effective degradability ratios between N and energy indicated a potential excess of N in rumen when DDGS samples were evaluated as single ingredient. This excess increased as the proportion of wheat in feedstock increased. Estimated intestinal digestibility of rumen bypass protein (IDP) was similar between wheat and wheat DDGS, but higher in corn DDGS than in corn. Blend DDGS had the highest IDP (93.9 %RUP). Due to the significantly different PC sub-fraction found in wheat DDGS originated at the different bio-ethanol plants, a large but numerical difference was detected in IDP (89.4 vs. 75.9 %RUP).<p> In Study 3, we used both the DVE/OEB System and the NRC 2001 Model to reveal the metabolic characteristics of DDGS protein and predict the protein supply to dairy cattle. The two models showed higher protein values (DVE or MP) for DDGS samples than for feedstock grains. The higher IDP for blend DDGS largely contributed to the higher protein value relative to wheat DDGS and corn DDGS (MP: 277 vs. 242 vs. 250 g kg-1 DM). Similarly, protein values differed significantly between the bio-ethanol plants mainly as a result of the numerical but large difference in IDP (MP: 272 vs. 223 g kg-1 DM). According to the two models, the degraded protein balance for DDGS products was higher than in the parental grains. Wheat DDGS showed the highest potential N excess (DBPNRC: 78 g kg-1 DM). For corn DDGS, however, the DVE/OEB System suggested a potential N excess (11 g kg-1 DM) while the NRC 2001 Model exhibited a potential N deficiency (-12 g kg-1 DM). The degraded protein balance for wheat DDGS was similar between the different bio-ethanol plants.<p> In conclusion, the chemical and biological characteristics of DDGS varied among types and between wheat DDGS samples manufactured at the different bio-ethanol plants. Thus, it is inappropriate to assume fixed values for the nutritive value of DDGS without considering factors such as type of grain used and bio-ethanol plant origin. Further research with higher number of samples will help to clarify the use of the chemical profile to predict energy values and the potential degradability of DDGS.

Emphasis on using the glycaemic index (GI) in addition to carbohydrate exchange lists has led to a greater variety of foods from which to choose for the diabetic population. Breakfast is regarded as the most important meal of the day and the glycaemic response to lunch can be improved by decreasing the GI of breakfast. However, most conventional breakfast cereals and bread exhibit a high GI. Dried beans have a low GI and various processes such as cooking and canning increase GI values, but still in the low GI range. In recent years, extrusion cooking has become one of the popular new processes developed by the food industry. Extrusion provides a convenient alternative for the ingestion of dry beans in the diet. Muffins are eaten by many South Africans and may be an ideal alternative for breakfast cereals and bread, especially if the GI of the muffins is low. The aim of this study was to determine the GI of a muffin baked with extruded bean flour and compare it to the GI of a muffin baked with whole wheat flour. Subjects and methodology: The study cohort consisted of ten healthy males and ten healthy females. Subjects randomly consumed test meals of glucose (the reference), bean muffins and whole wheat muffins on different days. Each test meal provided 509 available carbohydrate as analysed by the Englyst method. Results: The GI of the muffin baked with extruded bean flour (mean 53.0%, Confidence intervals (CI): 41.7; 64.2) was not significantly different from that of the whole wheat muffin (mean 55.5%, CI: 41.8; 69.2) but still in the low to intermediate GI category. Conclusion: Extrusion of dried beans results in a fine flour with relatively no intact starch which may explain the very low resistant starch content (1.6I100g) of the muffins. The small particle size of the fine flour could further have contributed to the higher than expected GI of the bean muffin because the size of the particle is inversely related to glycaemic response. Muffins baked with extruded dried bean meal are nevertheless regarded as an excellent choice for breakfast and as part of the prudent diet. Beans have additional health benefits and are included in the South African Food Based Dietary Guidelines. / Thesis (M.Sc. (Dietetics))--North-West University, Potchefstroom Campus, 2004.

The motivation of the research presented in this thesis was to investigate the potential of using a commercial 2.3 kW heat pump dehumidifier (HPD) simultaneously as a dryer for high-moisture agricultural products and for other domestic dehumidification/heating applications. A drying system incorporating the HPD was designed and constructed, along with instrumentation to gather data on the properties of process air as well as real-time weight of the material being dried. The HPD was equipped with an external water-cooled condenser that rejected excess heat out of the system. The design of the system allowed for conducting drying with recirculation of air as well as use of electrical heaters. In an open mode, the drying could be carried out simultaneously with room dehumidification and water heating in the secondary condenser. / The drying experiments were conducted with apple, tomato and agar gels. The system was found to be more effective in drying of material with higher amount of free moisture such as tomato. Comparisons were made between HPD assisted drying (partial and complete) and hot air drying (at 45°C and 65°C) in the same system using apple as the test material. Colour changes (L*a*b* values) in the samples were compared between treatments. It was observed that the degree of undesirable colour change was least in case of the HPD assisted system. The HPD dried fruit exhibited better rehydration properties than the hot air dried samples. Water activity of the HPD dried samples was noticeably lower than that of the hot air dried samples at the same water content, indicating that the residual moisture was probably held under higher tension. Histological observation indicated that there was a lesser degree of damage to the cellular structure of apple when dried with the HPD than when dried with hot air alone. / In terms of energy consumption, the process of HPD assisted drying is more expensive. Much of the energy input is rejected at the secondary condenser as excess heat. Unless this heat is recovered for another purpose, or the system is modified to reuse it for drying, the drying process must carry this loss entirely. The specific moisture extraction rate (SMER) for apple was as low as 0.1 kg per kWh with the HPD assisted system. The SMER values for drying at 45°C was 0.5 kg per kWh and was almost 0.8 kg per kWh at 65°C. / The HPD assisted drying system demonstrated the ability of heat pumps to link different energy related activities viz., drying, space dehumidification and water heating. The energy expenditure is expected to be impressive when considered for all the related applications. The concept of utilizing heat pumps on farms to link up different energy streams for better utilization of the low-grade heat sources is discussed. A possible drying efficiency assessment in the form of energy-based evaluation is proposed.