published_or_final_version / Mathematics / Master / Master of Philosophy

published_or_final_version / Mathematics / Master / Master of Philosophy

published_or_final_version / Humanities / Doctoral / Doctor of Philosophy

Frozen Marion (Rubus sp. hyb) and Evergreen blackberries (Rubus laciniatus) (whole berries, berries without seeds, and seeds alone) were acetone/ chloroform extracted. Phenolics were isolated using C₁₈ cartridges and polyamide resins, then characterized and measured by reversed-phase HPLC/diode array spectral techniques. The Polyamide isolated fractions of Marion berries contained four quercetin glycosides, one kaempferol glycoside, three acylated quercetin glycosides, (-)-epicatechin, and eight ellagic acid derivatives. Polyamide isolated fractions of Marion seeds had several procyanidins (including (+)-catechin and (-)-epicatechin), 11 tentative ellagitannins, and eight ellagic acid derivatives. (-)-Epicatechin and ellagic acid derivatives were the primary phenolics in blackberry fruits and seeds. Flavonols were the major component in whole berries, while procyanidins and ellagic acid derivatives were the primary phenolics in seeds. No flavonols were found in seeds. The phenolic profiles of Marion and Evergreen were qualitatively similar. Evergreen berries contained higher level of (-)-epicatechin, ellagic acid derivatives, and flavonols than Marion berries. Evergreen seeds were also higher in procyanidin content than Marion seeds, while Marion seeds were higher in ellagic acid derivatives. No ascorbic acid was found in any extracts. The total monomeric anthocyanin content of Marion berries (225 mg of Cyanidin 3-glucoside/100g) was 1.5 times higher than that of Evergreen berries (154 mg/100g). However, the total phenolics, total monomeric anthocyanins, oxygen radical absorbing capacity (ORAC), and ferric reducing antioxidant power (FRAP) values of Marion and Evergreen berries were not statistically different at the significance level 0.05. The total phenolics, ORAC, and FRAP values of Marion berries were 844 mg of gallic acid equivalent (GAE)/100g, 35.5 μmole of Trolox equivalent (TE)/g, and 79.1 μmole of TE/g, respectively. The total phenolics, ORAC and FRAP values of Evergreen berries were 822 mg of GAE/100g, 34.3 μmole of TE/g, and 74.2 (μmole of TE/g, respectively. Over all, Marion blackberries were higher than Evergreen blackberries with respect to phenolic content and antioxidant capacity. This study confirmed that blackberries contributed a significant source of phenolic antioxidants that may have potential health effects. Blackberry seeds, accounting for 5.0% of the weight of Marion berries and 5.6% of Evergreen berries, had very high phenolic content and antioxidant capacity; therefore they may be a potential source for nutraceuticals and natural antioxidants. / Graduation date: 2002

The present study was undertaken to analyze the vitamin E, total lipids, and cholesterol in regular and fat-reduced milk to assess whether decreases in fat result in lower vitamin E contents. Milk samples of varying fat contents (11%, 3.3%, 2%, 1% and 0.5% fat) were obtained from a local dairy on six different occasions, α-tocopherol was the major form of vitamin E found in different types of milk, γ-tocopherols and α-tocotrienol were found to a lesser extent in different milks. As the fat content of milk decreased from 11% to 0.3%, vitamin E content also decreased steadily. For example, raw milk as compared to non-fat milk had both a higher α-tocopherol contents (45.5 ± 4.59 μg/100 ml vs. 4.46 ± 0.54; p<0.0001) and a higher total lipids (3.46 ± 0.49 μg/100 ml vs. 0.30 ± 0.07 g/100 ml, (p [less than or equal to] 0.0001). The other detected forms of vitamin E, γ-tocopherol and α-tocotrienol, also varied as the total lipids. Vitamin E, cholesterol and total lipids increased as cream was added back to non-fat milk. For every 10 mg of cholesterol there was an increase of approximately 4 μg of α-tocopherol. For every 1 g increase in total lipid content, the α-tocopherol content increased by 17 μg. This study indicates that vitamin E; especially exotic forms of this vitamin are present in the dairy products analyzed. Also, vitamin E content varies with the total lipid and the cholesterol content. We suggest that vitamin E fortification of milk might be a reasonable approach to restore α-tocopherol intakes to those seen with whole milk. / Graduation date: 2000

Deterioration of the flavor of sterilized concentrated milk (SCM) is recognized as the principal limiting factor to commercial acceptance of this product. Although a number of volatile compounds have been identified in SCM, quantitative information on these compounds is lacking. It is therefore difficult to ascertain the significance of these compounds. The purpose of this investigation was to determine the identity of additional flavor compounds of stored SCM and to determine the concentrations of the major flavor compounds. Vacuum steam distillation was utilized to recover volatile flavor compounds from samples of SCM. The distillates were extracted with ethyl ether, and components of the ethereal flavor concentrates were separated by gas-liquid chromatography (GLC). Major components whose identity was unknown were collected from the GLC effluent, and were analyzed by capillary column GLC and mass spectrometry. A system for transferring trapped components directly onto a capillary GLC column was developed. 2-Furfural, which had not previously been identified in SCM, and 2-furfurol, which had not been identified as a component of any stored milk product, were identified in stored SCM. Commercial samples of SCM were placed in controlled storage, and subjected to flavor panel evaluation and a number of quantitative determinations at selected intervals of storage. The concentration of the odd-numbered n-methyl ketones, C₃-C₁₁, and of o-aminoacetophenone were determined by measuring the absorbance of their respective 2, 4-dinitrophenylhydrazone derivatives. The concentration of 2-furfurol was determined by a gas entrainment, on-column trapping GLC technique. Acid degree values were obtained by titration of SCM milk fat. Hydroxymethylfurfural (HMF) values were determined by measuring the absorbance of the HMF thiobarbituric acid reaction product. The methyl ketones and o-aminoacetophenone were found to exceed their flavor threshold concentrations after 13 weeks storage of SCM at 27°C. The concentration of 2-furfurol exceeded its threshold concentration after 26 weeks at 27°C, but not after 13 weeks. Acid degree values increased slowly, but did not reach significant levels through 26 weeks at 27°C. Hydroxymethylfurfural values increased slowly through the first 13 weeks at 27°C storage, followed by a marked increase during the second 13 weeks. Heat degradation of thiamine was studied as a possible source of volatile flavor compounds. Heating of thiamine solutions in phosphate buffer at pH 6.7 resulted in the production of volatile components of potential flavor significance. The identity of these components was studied by gas entrainment, on-column trapping GLC, collection of components, and capillary column GLC in conjunction with mass spectrometry. The system developed for the transfer of trapped components directly onto the capillary GLC column was utilized. Hydrogen sulfide, 2-methyl furan, 2-methyl thiophene and a compound which appeared to be a dihydro-2-methyl thiophene were identified as volatile heat degradation products of thiamine. / Graduation date: 1968

The purpose of the present study was to investigate the effect of a number of physical and chemical attributes upon muskmelon texture as described by sensory evaluation. Measurements of turgor pressure, percent moisture, total sugars, alcohol-insoluble-solids, three pectic fractions, total pectic materials, starch and cellulose were performed on 50 melons. The melons were purchased at random from a retail market in Corvallis, Oregon, over a five-week period during July and August, 1966. Subjective evaluation of textural quality was provided by a five-membered panel employing a pre-tested ballot. On five-point scales, judges rated resistance to cutting, resistance to biting, resistance to crushing, crispness, fibrousness and sweetness. Simple and multiple correlation analyses were performed to elucidate relationships between the objective and subjective observations. Considerable variation was found among melons for most of the attributes. Variation was largest in the case of water-soluble pectic substances and cellulose and least for alcohol-insoluble-solids. According to the results of this study, melon texture is determined to a great extent by the type and amount of cell wall constituents. Significant multiple correlations were found between cell wall constituents, cellulose and protopectin, and sensory panel scores for resistance to cutting, resistance to biting, resistance to crushing and crispness. Fruit maturity, as inferred from starch and protopectin content, also exerted an effect upon texture. Significant multiple correlations were found between starch and protopectin and panel scores for resistance to cutting, resistance to crushing and crispness. Although not specifically related to texture, a significant and positive simple correlation was found between total sugars and sweetness. Similarly, significant negative correlations were found between starch and total sugars and starch and sweetness. Turgor pressure, percent moisture, alcohol-insoluble-solids, total sugar, water-soluble pectic substances, pectates-pectinates and total pectic materials were found not to be reliable indicators of muskmelon texture. Although turgor pressure did not exhibit a significant relationship to any textural aspects, a trend was observed in the data. As a result of this observation and difficulty encountered in measuring turgor pressure, further work with this variable is recommended. Proximate composition of the melons analyzed compared favorably with published data. This observation lends confidence to the methods and analyses employed. Large standard deviations calculated for some of the attributes measured emphasize the extent of variation among melons, the difficulty in assessing texture in an objective manner and the problem encountered in marketing and purchasing the fresh fruit. / Graduation date: 1968

No description available.

An investigation was made of physicochemical and functional properties of a polysaccharide, arabinogalactan (TAG), found in the tepary bean, Phaseolus acutifolius var. latifolius, an arid adapted legume with substantial protein and starch content. TAG has specific functional and sensory properties which could be of value in foods and industrial products. The polysaccharide was isolated by a sequence of steps depending on initial extraction by trichloroacetic acid. Isolated TAG was obtained from bean flour in 3.7% yield and contained 3.6% protein; fractional precipitation provided further purification and gave fractionated TAG in 1.8% yield with a protein content of 0.9%. The purified product was composed primarily of two monosaccharide monomers, arabinose and galactose, in the ratio 2.07:1.00. Fractionated TAG was separated further by gel filtration and showed the presence of two arabinogalactans in the ratio of 9:4 with similar properties and approximate molecular weights of 500,000 and 30,000. The influence of concentration, temperature, pH and presence of sugars and electrolytes on the viscosity of fractionated TAG was studied. The specific viscosity at 1% w/v (17.84), was much greater than that of larch arabinogalactan (0.08) or soluble starch (0.39). Optical rotation measurements of temperature dependent conformational changes gave evidence for the maintenance and stabilization of the native conformation of TAG by guar gum in a mixed gel. No synergism was observed. TAG in 4% concentration produced oil in water emulsions with excellent stability over at least five months. Loaf and crumb characteristics of wheat bread were influenced by TAG at a supplementation level of 0.2%. Sensory evaluation indicated excellent color, flavor, aroma, mouthfeel, texture and overall acceptability. Substantial advantages were also afforded by TAG supplementation of rice flour bread which is formulated specifically for gluten-allergic people. Significant improvements were found in loaf and crumb quality and in sensory properties. The inclusion of TAG in a variety of other foods could be expected to enhance rheological properties as well as improve thickening, emulsification, emulsion stabilization, gas-holding and dough-raising.

Molecular gas in other galaxies is generally studied by observations of CO emission; a conversion from CO integrated intensity to H₂ column density must be made. Modelling of the emission from an ensemble of molecular clouds shows that these conversion factors are sensitive to temperature, so that molecular gas masses in galaxies with high star formation rates have probably been overestimated. Conversely, models of molecular clouds in low metallicity systems (such as irregular galaxies) demonstrate that the use of CO as a tracer can severely underestimate the molecular gas abundance. The observed properties of dark clouds and high latitude clouds are consistent with clouds in equilibrium with an intercloud pressure of P/k ≈ 10⁴. Detailed comparison of the CO and 170μm emission from the disks of NGC 6946 and M51 shows that the far-infrared flux must arise from dust in molecular clouds, not atomic clouds; this emission may be powered by embedded young stars or by the interstellar radiation field. The interpretation of the ratio of infrared to CO luminosities as a star formation efficiency is of dubious validity. Modelling of the observed CO and far-infrared emission from a sample of galactic nuclei shows that roughly half of the CO flux is produced by very active star-forming clouds with warm CO. The constraints placed on star formation models by abundance gradients in galaxies suggests that radial gradients in star forming efficiency generally exist in galaxies. The actual distribution of molecular gas in galaxies may be closely tied to the radial mass distribution.