Browsing by Subject "dietary fiber"

Now showing 1 - 4 of 4
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    The Effects of Diverse Dietary Interventions on Markers of Colon Cancer Risk in Carcinogen-Treated Rodents
    (2023-12) Bailey, Allison
    Colon cancer, a leading cause of cancer-related deaths worldwide, is largely preventable through lifestyle modifications including diet. While epidemiologic evidence associates foods rich in phytochemicals and dietary fiber with a reduced risk of cancer, the chemopreventive efficacy of specific dietary interventions to reduce colon cancer risk is still uncertain. In four studies, this thesis aims to explore the effects of three dietary interventions (red wheat, apiaceous and cruciferous vegetables, and prebiotic dietary fiber) on colon cancer risk in rodents and to characterize the effectiveness of the Total Western diet as a rodent background diet for colon cancer and inflammatory disease models. The first study used a mouse model to explore the effects of different wheat classes and milling fractions on colon cancer prevention. However, the results were inconclusive. Ultimately this mouse model was unsuitable due to challenges with the carcinogen dosage and toxicity, tissue incompatibility with a major biomarker assay, and the limited volume of tissue available for study due to a mouse’s small size. The second study continued this work using a rat model and added the variable of a comparison of background diets: a standard, optimized rodent diet (AIN-93G) or a newer diet based on the typical Western diet (Total Western Diet; TWD). We found some evidence that whole red wheat may reduce CC risk, but only with the TWD background diet, indicating that TWD may be a better background diet for CC rodent models. The third study examined the effects of apiaceous and cruciferous vegetables on colonic inflammation and compared TWD with the Diet Induced Obesity (DIO) model, which uses the same micronutrient concentrations as the AIN-93G diet. Vegetables decreased colon inflammation, but only with the TWD background diet, further supporting its use in modeling lifestyle diseases. The final study examined the effects of prebiotic dietary fibers, including the novel prebiotic fiber polylactose, on CC risk. We found no evidence that polylactose decreases CC risk, but limited evidence that polydextrose decreases CC risk indicates the need for further research in this area. Taken together, these studies expand our understanding of the effect of diet on CC risk by highlighting the detrimental role of mild micronutrient deficiency modeled by the TWD and providing modest support for consuming nutrient rich foods such as whole red wheat, apiaceous and cruciferous vegetables, and prebiotic fibers to reduce CC risk.
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    Extraction, Modification, and Chemical Characterization of Protein and Dietary Fiber from Camelina Sativa
    (2018-07) Boyle, Claire
    Camelina sativa, a sustainable short-season cover crop, is an oilseed (35% oil) gaining interest due to the increasing global demand for sustainably sourced ingredients. Camelina provides numerous agricultural benefits—low production cost, low nitrogen requirements, drought resistance, cold weather tolerance, and short growing season—in addition to being high in protein (20%) and dietary fiber (30%), which are two of the fastest growing segments of the food ingredient market. In order to create functional, market-viable ingredients from camelina, the following need to be explored: efficient means of protein extraction, evaluation of protein functional properties, and chemical characterization of the dietary fiber constituents. The objectives of this study were as follows: (1) determine the impact of oil pressing conditions and protein extraction protocol on protein yield and content; (2) characterize structural differences in proteins extracted following salt precipitation and pH solubilization; (3) determine the impact of structure and enzymatic modification on the functionality of the different protein extracts; (4) isolate, quantify, and characterize the insoluble and soluble dietary fiber fractions of defatted camelina meal (DCM) prepared by two different oil pressing conditions. Protein extraction by pH solubilization and salt precipitation was tested and optimized. Camelina meal obtained from hot and cold press was further defatted by hexane and analyzed for protein content. Protein from DCM was extracted following degumming and pH solubilization at pH 12, separating non-protein material by centrifugation, acidifying the supernatant to pH 5 to precipitate out the protein, neutralizing and desalting. Protein from DCM was also extracted following salt precipitation, first by solubilizing the protein using 0.05 M phosphate buffer (pH 8, 1 M NaCl), followed by precipitation using 85% saturated ammonium sulfate solution, and desalting. To produce protein hydrolysates, extracted proteins were subjected to hydrolysis with Aspergillus oryzae protease by pH-stat methodology to a degree of hydrolysis less than 8%. Protein purity of the extracts was analyzed, and mass balances were tracked in order to evaluate extraction yields. The denaturation state, protein profile, and surface hydrophobicity of the protein extracts were determined using DSC, SDS-PAGE, and a fluorometric assay, respectively. Functionality was evaluated by determining protein solubility as well as emulsification, foaming, and gelation properties. Total dietary fiber (TDF) from DCM was determined following the AOAC method 2011.25, and three fractions —insoluble dietary fiber (IDF), soluble dietary fiber that precipitates in 78% ethanol (SDFP), and soluble dietary fiber that is soluble in 78% ethanol (SDFS) — were isolated preparatively. IDF and SDFP were analyzed spectrophotometrically for pectin content. The monomers of IDF and SDFP fractions were determined by alditol acetate formation and measured by GC-FID. Degree of pectin methylation (DM) of SDFP was determined by 1H NMR. The degree of polymerization (DP) of saccharides in the SDFS fraction (DP 2 – DP 7) was determined by liquid chromatography-ESI-mass spectrometry (LC-MS) using a ligand-exchange stationary phase and quantified by high performance anion exchange chromatography coupled with a pulsed amperometric detector (HPAEC-PAD). Disaccharides in DCM were differentiated and quantified spectrophotometrically following standard enzymatic assays. Compared to camelina protein concentrates (CPC) produced by alkaline pH extraction, CPC produced by salt extraction were less denatured and more functional. The functionality of the salt extracted CPC was comparable and sometimes better than that of soy protein isolate (SPI). Specifically, the solubility of the salt extracted CPC at pH 3.4 was significantly (P < 0.05) higher than that of SPI. Additionally, salt extracted CPC had significantly higher emulsification capacity and foaming capacity than SPI. On the other hand, the gelation property of CPC was inferior to that SPI, an observation attributed to the molecular size of camelina protein compared to SPI. Upon hydrolysis of CPC with Aspergillus oryzae protease, a limited benefit to solubility was noted at pH 7 post thermal treatment. TDF of DCM averaged 51.2% (45.3 – 49.1% IDF, 2.00 – 5.98% SDFP, 1.1 – 1.2% SDFS). The SDFS fraction was comprised mainly of stachyose and raffinose, which is in line with other Brassicaceae crops. The chief disaccharide present in DCM was verified to be sucrose (2.43 – 3.36%). Free glucose and fructose were also present in the SDFS fraction. Of the pectic polysaccharides measured in SDFP, low methoxyl pectin represented the major constituent, with a DM of 12.5 – 14.5%. Based on alditol acetate analysis, glucose was the main monomer in the IDF fraction. Other monosaccharides detected in the IDF fraction were xylose, arabinose, mannose, and galactose. The monosaccharide composition indicated the presence of cellulose, xyloglucans, galactomannans, and arabinoxylans in the IDF fraction. In SDFP, the monosaccharides rhamnose, arabinose, galactose, and mannose were evenly distributed. Monomer composition of the SDFP fraction indicated the presence of pectin and galactomannans. Results show that camelina meal contains a significant amount of protein and dietary fiber that can be isolated into functional ingredients. This is the first study to provide a comprehensive evaluation of protein and dietary fiber from camelina as potential alternatives to traditional ingredients. Further work is needed to understand how isolated camelina ingredients interact in various food matrices.
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    Prediction of Available Energy in Dairy Cow Rations from Dietary Fiber
    (Minnesota Agricultural Experiment Station, 1987) Donker, J.D.
    Two published equations and four derived equations that predict dietary energy from dietary crude or acid detergent fiber were evaluated for accuracy. The equations estimated total digestible nutrients, digestible energy, metabolizable energy or net energy lactation of diets of cows completing 480 lactations in which mean dietary crude fiber varied among seven dietary groups from 17 4 to 225 g crude fiber per kilogram of dry matter consumed. Intakes of available dietary energy were compared against feeding standard requirements. Mean quotients obtained by dividing energy intakes from equations by energy requirements (concurrence values) varied from 1.00 to 1.05 among equations. Concurrence values decreased as dietary fiber increased. Available dietary energy content expressed in any common energy term was accurately predicted from dietary fiber for full-fed milking Holsteins through use of equations presented in the text.
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    Turning Low Value Whey Ingredients into Value Added Products
    (2015-01) Reid, Elizabeth
    Low value dairy products such as lactose and acid whey, pose a huge opportunity to be converted into value-added products. This research evaluated the effect of formula and processing conditions on the polymerization of lactose by reactive extrusion into indigestible oligomers. Three citric acid concentrations (2%, 4% and 6%) and two feed rates (15 kg/hr and 30 kg/hr) were evaluated for their effect on the polymerization of lactose. Samples extruded at 15 kg/hr resulted in a higher yield of indigestible oligomers (46.7-56.4%) than at 30 kg/hr (33.7-43.5%). A successful cleanup procedure for Greek yogurt acid whey was developed so that it could be concentrated and drum dried. Heat treating the acid whey resulted in a reduction of protein, fat, and moisture. Washing the condensed whey resulted in a reduction of lactic acid, protein, and a lighter colored drum dried product.