No description available.

Protein-lipid complexes are known to result from complex molecular interactions which contribute to physiochemical and functional properties of foods. To identify the interactions of food proteins with lipids and the associated changes in properties, the following factors were investigated: incubation temperature, pH, type of lipids (phospholipid, triglyceride and fatty acids) and different proteins (ovalbumin and soybean glycinin). The effects of lipids on physiochemical and functional characteristics of ovalbumin and glycinin were investigated using polyacrylamide gel electrophoresis (PAGE), fluorescence, differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectroscopy, and emulsification and gelation properties. / The results showed that pH, temperature and the type of lipids affected both ovalbumin-lipid interactions and physiochemical properties of ovalbumin. Changes in the electrophoretic behavior of ovalbumin were related to the presence of lipids, and the relative fluorescence of ovalbumin decreased in the presence of lipids at different pH values. In addition, lipids increased the stability of ovalbumin as revealed by the thermal denaturation (Td) and by the enthalpy transition (DeltaH). FTIR spectra in the amide I absorption region revealed that lipids affected the secondary structure of ovalbumin. Changes in the integrated intensity of the amide II band between (1520--1555) cm -1 in the presence of D2O showed that H-D exchange of ovalbumin decreased in the presence of lipids. Emulsifying properties, gel strength and water holding capacity (WHC) of ovalbumin increased significantly (P < 0.05) in the presence of lipids. Scanning electron microscopy (SEM) showed difference in the microstructure of ovalbumin gel in the presence of different lipids. The more pronounced effect of lipids was observed with lecithin and the lowest was with stearic acid. The order of magnitude for the effects of lipids on physiochemical and functional properties of ovalbumin was: lecithin > cocoa butter > oleic acid > linoleic acid > linolenic acid > stearic acid. It is likely that the degree of polarity of lipids play an important role in protein-lipid interactions and in the enhancement of the functional properties of ovalbumin. / The effects of soybean oil (SO), soybean lecithin (SL) and a mixture of both (SOL) on physiochemical and functional properties of soybean glycinin were studied at pH 8.0, with incubation at 40°C. Changes in the electrophoretic behavior were related to the presence of lipids. Relative fluorescence of glycinin decreased in the presence of lipids. Lipids increased the thermal stability (Td) of glycinin from 89.7°C to 92.0°C, 94.3°C and 93.4°C with SO, SL and SOL respectively. FTIR spectra indicated changes in both; the secondary structure and H-D exchange of glycinin in the presence of lipids. Gel strength, WHC and emulsifying properties of glycinin increased significantly (P < 0.05) in the presence of lipids; the order of consequence increase was: SL > SOL > SO. SEM showed difference in the microstructure of glycinin gels with the different lipids used. Overall, the results demonstrate both quantitative and qualitative effects on the physiochemical and functional properties of ovalbumin and glycinin as a result of protein-lipid interactions.

Chickpea (Cicer Arietinum) was germinated for different lengths of time to determine the influence of germination on the functional and nutritional properties of this legume. Chemical analysis of the flours showed a very significant increase in vitamin C and in lysine during germination. Vitamin C values ranged from 1.2 to 15.6 mg/100 g and lysine from 10.5 to 13.5 g/100g of protein for the intact and the 48 hr-germinated chickpea, respectively. Starch content decreased 15.5% and soluble sugars increased 20% after only 24 hr of germination. Germination decreased trypsin inhibitor activity by 28%. Chickpea and 24 hr germinated chickpea were used as ingredients in the preparation of several products. Germination increased acceptability in some of these products by modifying their rheological and sensory properties. Seed germination enhanced significantly the nutritional quality of chickpea protein. Protein efficiency ratio associated with the germinated chickpea diets compared favorably to that obtained with the casein diet. Protein digestibility decreased as germination time increased. Essential amino acid availability did not change after 24 hr of germination, but small decreases were observed after 48 hr. Protein and starch were studied separately to determine their influence on the observed modifications. No significant changes were found in the concentration of proteins in germinated chickpea even after 72 hr of germination as indicated by densitometry scans of SDS-PAGE patterns. Starch was isolated from intact and germinated chickpeas and characterized by several of its physicochemical properties and its susceptibility to alpha-amylase hydrolysis. Germination increased substantially starch digestibility and modified some of the physico-chemical properties of starch. Scanning electron microscopy (SEM) showed no apparent differences between starches except for a tendency of the germinated chickpea starch to clump. These results suggest that changes in texture, consistency and other physical parameters observed on the germinated chickpea-based products may be attributed mostly to starch.

The lack of information regarding the inheritance of the duration and rate of grain filling, and the possible relationship between grain fill and grain protein content in wheat prompted this study. Early maturing Chinese cultivars, 'AI Feng 2' and 'CB 83-52', and late maturing cultivars adapted to Oregon, 'Stephens' and 'Yamhill Dwarf', were examined for vernalization and photoperiod responses. Progeny from a diallel cross of the genotypes was evaluated for grain filling parameters, grain protein content and other agronomic traits for two years. 'Yamhill Dwarf' required six weeks of vernalization, while other cultivars needed only four weeks. The two Oregon developed genotypes were more sensitive to photoperiod than Chinese genotypes. Variation in developmental patterns among genotypes was related to differences in leaf number, spikelet number, rate of spikelet initiation, and rate of grain fill. Compared to solid planting, space-planting reduced the grain filling period. Significant genotypic variation for grain filling rate, duration, and kernel weight was observed in both seasons. Genotype X year interaction was not significant for any of the grain filling traits. General combining ability effects for grain filling rate, duration, and kernel weight were much larger than specific combining ability effects. Additive gene action made the major contribution to the inheritance of the grain filling traits. However, dominance effects appeared also to be involved in the genetic control of grain filling duration and kernel weight. Narrow sense heritability estimates were high for all three grain filling traits. Results indicated that early generation selection for both duration and rate of grain fill should be effective in these populations. Rate, but not duration of grain fill was closely associated with kernel weight. There was an inverse relationship between duration and rate of grain filling. Kernel protein percentage was positively associated with duration, but negatively related to rate of the grain filling. Results suggest that starch and protein accumulations in the kernel are two highly independent processes and may not necessarily compete for assimilates or energy. It may be necessary under the environments of this study to increase the duration of the grain fill to obtain high protein content with acceptable grain yield. / Graduation date: 1993

A negative relation between grain protein content and grain yield is frequently observed in wheat (Triticum aestivum L. em Thell) i.e. as grain yield increases, grain protein decreases. It has been suggested that the inverse relation between grain yield and protein is in part the result of developing high yielding semi-dwarf wheat cultivars with an increased harvest index. This investigation was undertaken to determine the nature of the possible association of grain yield and protein content as influenced by harvest index, biological yield, plant height and kernel weight in winter wheat populations grown in Oregon. Progenies derived from three crosses of winter wheat were solid-planted in two environments during two seasons. Phenotypic correlations showed a moderate negative association of grain protein content with both grain yield and harvest index. The magnitude of the genetic correlations suggested the presence of genetic relationships among these traits. Selection for harvest index among these crosses could cause a correlated reduction of grain protein content. To investigate if the relationships between grain protein content and selected plant growth traits were similar when grown under space-planted and solid seeded stands, progenies of two winter wheat crosses were evaluated during two seasons. Performance for grain yield and grain protein content was different under contrasting sowing densities as values were not correlated between sowing densities. This indicates the need to evaluate these traits in solid-seeded stands. Harvest index, as well as plant height and heading date, could be effectively selected under space-planted or solid seeded conditions. Associations among traits were reliably estimated in space-planted stands. To evaluate the effect on grain protein content when grain yield and harvest index are modified, the plant growth regulator Paclobutrazol was applied to selected winter wheat genotypes under field and greenhouse conditions. Paclobutrazol increased grain yield and harvest index values of all genotypes in the greenhouse, while only some genotypes improved these traits under field conditions. Grain protein content, however, remained unchanged. Higher grain yields were obtained in both greenhouse and field experiments. / Graduation date: 1991

Three experiments were conducted to study the sensitivity of the pH-stat (in vitro) method in the prediction of true digestibility (TD), as measured by amount of base added, of plant proteins, either alone or in the presence of specific additives (nitrogen-free mixture, vitamin mixture and/or mineral mixture) as part of a complete diet of plant proteins that had been subjected to various levels and forms of heating. The in vitro TD values were then compared with TD values obtained in. vivo (Wistar rats). In experiment 1, the effect of temperature (dry-heating at 80, 100, 120, 150, 180 and 240° C or autoclaving at 121° C) and time (30, 60, 120 and 240 minutes) of heat application on in vitro base consumption (BC) was measured in 3 grains (wheat, barley and sorghum) and whole defatted soybeans. The largest increase in BC measured by the pH-stat method was that of soybeans in response to 30 minutes of autoclaving. Dry heating had various effects on the BC by soybeans, depending upon temperature and time of application, but none of the treatments was as beneficial as autoclaving. Mild, dry-heating of grains at 80-120° C improved BC slightly. The improvement was most marked for wheat. Both dry-heating of grain at temperatures above 120° C and autoclaving reduced the BC significantly for all durations. In experiment 2, the effect of inclusion of non-protein dietary components (minerals, vitamins and a nitrogen-free mixture, singly and in combination) on in. vitro BC measured by the pH-stat method of wheat and fat-extracted soybeans (both proteins in the raw and autoclaved forms) was monitored. For the wheat treatments, the inclusion of a mineral mixture significantly (p<0.001>) increased digestibility. This effect was greatest with autoclaved wheat. It was concluded that, in general, the presence of minerals increased the rate of hydrolysis. With raw soybeans, the distinction between treatments was less well-defined. The treatments containing vitamin or nitrogen-free and mineral combination mixtures were digested to a significantly greater extent than the raw soybeans alone. With autoclaved soybeans, additives had no effect. This lack of response to additives may have been due to the rather large amount of base required by the autoclaved soybean protein alone. In experiment 3, a series of rat-feeding trials were conducted in conjunction with in. vitro digestions. Diets were fed to groups of Wistar rats to determine TD, Biological Value (BV), and Net Protein Utilization (NPU) in vivo. Although BV was measured it was not relevant for this work. Concurrently, the same diets were tested for in. vitro TD by the pH-stat method. Specific regression equations were developed for each protein-type tested, after it was determined that a much lower correlation coefficient was obtained when one general equation was utilized. The newly-developed equations followed the format y = a + bx, where y = TD (as a part of one), a = the y-intercept, b = slope of the function and x = ml 0.10N NaOH added during the 10-minute digestion. Regression equations, correlation coefficients (r) and standard errors for each regression (s) between in. vitro and in vivo true digestibility of proteins were as follows; Soybean, soybean (autoclaved), soybean/wheat combinations (n = 6) r = 0.93 TD = 0.7868 + 0.2175x s = 0.018 Sorghum (raw, autoclaved, 90° C, 120° C, 180° C dry-heated, steamed) (n = 6) r = 0.92 TD = 0.4575 + 1.8841x a = 0.058 Alfalfa pellets/hay in combination with either wheat or barley (n = 13) r = 0.91 TD = 0.3446 + 1.0356x s = 0.046Alfalfa hay and barley combinations (n = 5) r = 0.96 TD = 0.2360 + 1.3194x s = 0.048 Grains (19 barleys, 10 triticales, 6 sorghums, and 2 wheats) (n = 37) r = 0.74 TD = 0.7419 + 0.4759x s = 0.044 In general, it can be stated that the pH-stat method is a useful method for screening proteins for the effect of various treatments on digestibility. Damage due to abnormally severe processing conditions (i.e. heating) is readily detected by the pH-stat technique as indicated by a decrease in the amount of base consumed during enzymatic hydrolysis. / Land and Food Systems, Faculty of / Graduate

No description available.

Call number: LD2668 .T4 1985 W8 / Master of Science

Price premiums and discounts are currently paid for various classes of wheat in the US marketplace. These premiums and the known heterogeneity of grain protein across landscapes beg the question of whether grain could be separated on the farm to maximize revenues. Theoretically, the concavity or convexity of a price function defines if an opportunity to segregate grain exists. Although this is true, prices in the market place are paid in stepped increments, which result in unique revenue maximizing solutions. This study was conducted to determine the economic feasibility of segregating wheat by protein content on the combine harvester during harvest. Both web-based and spreadsheet calculators were built to predict the best point in which to segregate a crop at, as well as define the protein level and quantity of each segregated volume of grain. The costs of segregation vary by operation, but fixed, variable, and opportunity costs are estimated to total $0.1739 bu⁻¹ if segregation is used every year. Revenue gains varied with the price schedule, field mean protein value, and the standard deviation of protein. Revenue gains increased in proportion to the size of a price step in a price schedule. Soft white winter wheat showed the greatest potential for segregation; however, on average yearly expected premiums are less than $.05 bu⁻¹, well below total variable costs. Price schedules occur which allow for profits of over $1.00 bu⁻¹ from segregation, although these are not the norm. Historically, on-combine grain segregation would not be economically feasible for the average producer. However, under certain supply and demand conditions, premiums occur that would make on-combine grain segregation profitable. Individuals will have to evaluate the feasibility on a case-by-case basis. / Graduation date: 2013

by Wong Ka Hing. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2000. / Includes bibliographical references. / Abstracts in English and Chinese. / Dedication --- p.i / Thesis committee --- p.ii / Acknowledgements --- p.iii / Abstract --- p.iv / Abstract (Chinese version) --- p.vi / Table of contents --- p.viii / List of tables --- p.xv / List of figures --- p.xviii / List of abbreviation --- p.xix / Chapter Chapter one: --- General introduction / Chapter 1.1. --- Definition --- p.1 / Chapter 1.2. --- Classification --- p.2 / Chapter 1.3. --- Potential food use of seaweeds --- p.7 / Chapter 1.4. --- Hong Kong seaweeds --- p.10 / Chapter 1.5. --- Sargassum species --- p.12 / Chapter 1.6. --- Hypnea species --- p.13 / Chapter 1.7. --- Ulva species --- p.14 / Chapter 1.8. --- Design of research project --- p.15 / Chapter Chapter two: --- "Effect of diflerent drying methods on proximate composition, amino acid profile and some physico-chemical properties of brown seaweeds, Sargassum hemiphyllum, Sargassum henslowianum and Sargassum patens" / Chapter 2.1. --- Introduction --- p.20 / Chapter 2.2. --- Materials and methods --- p.23 / Chapter 2.2.1. --- Sample preparation --- p.23 / Chapter 2.2.2. --- Proximate analysis --- p.26 / Chapter 2.2.2.1. --- Crude protein content --- p.26 / Chapter 2.2.2.2. --- Ash content --- p.26 / Chapter 2.2.2.3. --- Total dietary fiber (TDF) content --- p.27 / Chapter 2.2.2.4. --- Crude lipid content --- p.28 / Chapter 2.2.2.5. --- Carbohydrate content --- p.29 / Chapter 2.2.2.6. --- Moisture analysis --- p.29 / Chapter 2.2.3. --- Amino acid analysis --- p.30 / Chapter 2.2.3.1. --- "Amino acids excluding cystine, methionine and tryptophan" --- p.30 / Chapter 2.2.3.2. --- Cystine and methionine --- p.31 / Chapter 2.2.4. --- Physico-chemical properties --- p.32 / Chapter 2.2.4.1 --- Swelling capacity (SWC) --- p.32 / Chapter 2.2.4.2. --- Water holding capacity (WHC) --- p.32 / Chapter 2.2.4.3. --- Oil holding capacity (OHC) --- p.33 / Chapter 2.2.5. --- Statistical analysis --- p.34 / Chapter 2.3. --- Results and discussion --- p.34 / Chapter 2.3.1. --- Proximate composition --- p.34 / Chapter 2.3.2. --- Amino acid composition --- p.39 / Chapter 2.3.3. --- Physico-chemical properties --- p.42 / Chapter 2.3.4. --- Conclusions --- p.46 / Chapter Chapter three: --- "Effect of different methods on protein extarctability, in vitro protein digestibility and amino acid profile of seaweed protein concentrates isolated from brown seaweeds, Sargassum hemiphyllum, Sargassum henslowianum and sargassum patens" / Chapter 3.1. --- Introduction --- p.48 / Chapter 3.2. --- Materials and methods --- p.51 / Chapter 3.2.1. --- Sample preparation --- p.51 / Chapter 3.2.2. --- Extraction of seaweed protein concentrates --- p.51 / Chapter 3.2.3. --- Precipitation of seaweed protein concentrates --- p.52 / Chapter 3.2.4. --- Crude protein content analysis --- p.53 / Chapter 3.2.5. --- Extraction of total phenolic compounds --- p.53 / Chapter 3.2.6. --- Determination of total phenolic compounds --- p.54 / Chapter 3.2.7. --- In vitro protein digestibility --- p.55 / Chapter 3.2.8. --- Amino acid analysis --- p.56 / Chapter 3.2.9. --- Statistical analysis --- p.56 / Chapter 3.3. --- Results and discussion --- p.56 / Chapter 3.3.1. --- Effect of oven- or freeze-drying on protein extractability from seaweeds --- p.57 / Chapter 3.3.1.1. --- Total crude protein and total phenolic content in seaweeds --- p.57 / Chapter 3.3.1.2. --- "%Nitrogen, %protein, sample dry weight, amount of protein extracted and %yield of PCs" --- p.60 / Chapter 3.3.2. --- Effect of oven- and freeze-drying on protein quality of seaweed PCs --- p.62 / Chapter 3.3.2.1. --- Total phenolic content and in vitro protein digestibility of seaweed PCs --- p.62 / Chapter 3.3.2.2. --- Amino acid composition --- p.64 / Chapter 3.3.3. --- Conclusions --- p.67 / Chapter Chapter four: --- "Proximate composition, amino acid profile and some physico- chemical properties of some red (Hypnea charoides and Hypnea japonica) and green seaweeds (Ulva lactuca)" / Chapter 4.1. --- Introduction --- p.68 / Chapter 4.2. --- Materials and methods --- p.71 / Chapter 4.2.1. --- L Sample preparation --- p.71 / Chapter 4.2.2. --- Proximate analysis --- p.71 / Chapter 4.2.3. --- Amino acid profile --- p.73 / Chapter 4.2.4. --- Physico-chemical properties --- p.73 / Chapter 4.2.5. --- Statistical analysis --- p.74 / Chapter 4.3. --- Results and discussion --- p.74 / Chapter 4.3.1. --- Proximate composition --- p.74 / Chapter 4.3.2. --- Amino acid composition --- p.78 / Chapter 4.3.3. --- Physico-chemical properties --- p.81 / Chapter 4.3.4. --- Conclusions --- p.86 / Chapter Chapter five: --- In vitro protein digestibility and amino acid profile of seaweed protein concentrates isolated from some red (Hypnea charoides and Hypnea japonica) and green seaweeds (Ulva lactuca) / Chapter 5.1. --- Introduction --- p.88 / Chapter 5.2. --- Materials and methods --- p.89 / Chapter 5.2.1. --- Sample preparation --- p.89 / Chapter 5.2.2. --- Extraction and precipitation of seaweed PCs --- p.90 / Chapter 5.2.3. --- Crude protein analysis --- p.90 / Chapter 5.2.4. --- Extraction and determination of total phenolic contents --- p.90 / Chapter 5.2.5. --- In vitro protein digestibility --- p.91 / Chapter 5.2.6. --- Amino acid analysis --- p.92 / Chapter 5.2.7. --- Statistical analysis --- p.92 / Chapter 5.3. --- Results and discussion --- p.93 / Chapter 5.3.1. --- Protein extractability --- p.93 / Chapter 5.3.1.1. --- Crude protein and total phenolic contentin seaweeds --- p.93 / Chapter 5.3.1.2. --- "%Nitrogen, %protein, sample dry weight, amount of protein extracted and %yield of PCs" --- p.95 / Chapter 5.3.2. --- Protein quality --- p.97 / Chapter 5.3.2.1. --- Total phenolic content and in vitro protein digestibility of seaweed PCs --- p.97 / Chapter 5.3.2.2. --- Amino acid composition --- p.99 / Chapter 5.3.3. --- Conclusions --- p.103 / Chapter Chapter six: --- Biological evaluation on protein quality of seaweed protein concentrates isolated from Hypnea charoides and Hypnea japonica / Chapter 6.1. --- Introduction --- p.104 / Chapter 6.2. --- Materials and methods --- p.114 / Chapter 6.2.1. --- Sample preparation --- p.114 / Chapter 6.2.2. --- Extraction and precipitation of seaweed protein concentrates --- p.114 / Chapter 6.2.3. --- Diet preparation --- p.115 / Chapter 6.2.4. --- Rat bioassay --- p.117 / Chapter 6.2.5. --- Biological indices --- p.118 / Chapter 6.2.6. --- Statistical analysis --- p.119 / Chapter 6.3. --- Results and discussion --- p.119 / Chapter 6.3.1. --- Protein quality of seaweed PCs --- p.119 / Chapter 6.3.2. --- Weight of major organs --- p.126 / Chapter 6.3.3. --- Conclusions --- p.129 / Chapter Chapter seven: --- Functional properties of protein concentrates isolated from Hypnea charoides and Hypnea japonica / Chapter 7.1. --- Introduction --- p.130 / Chapter 7.2. --- Materials and methods --- p.136 / Chapter 7.2.1. --- Sample preparation --- p.136 / Chapter 7.2.2. --- Preparation of protein concentrates --- p.137 / Chapter 7.2.3. --- Nitrogen solubility --- p.137 / Chapter 7.2.4. --- Water and oil holding capacity --- p.138 / Chapter 7.2.5. --- Viscosity --- p.139 / Chapter 7.2.6. --- Emulsifying activities and emulsion stability --- p.140 / Chapter 7.2.7. --- Foam capacity and foam stability --- p.141 / Chapter 7.2.8. --- Statistical analysis --- p.142 / Chapter 7.3. --- Results and discussion --- p.142 / Chapter 7.3.1. --- Nitrogen solubility --- p.142 / Chapter 7.3.2 --- Wafer and oil holding capacity --- p.145 / Chapter 7.3.3. --- Viscosity --- p.147 / Chapter 7.3.4 --- Emulsifying activities and emulsion stability --- p.149 / Chapter 7.3.5. --- Foam capacity and foam stability --- p.153 / Chapter 7.3.6. --- Conclusions --- p.157 / Chapter Chapter 8: --- Conclusions --- p.158 / References --- p.160 / Appendix --- p.195 / Related publications --- p.202