Browsing by Author "DiVerdi, Joseph, committee member"
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Item Open Access Effects of time and temperature during melanging on the volatile profile of dark chocolate(Colorado State University. Libraries, 2019) Clark, Caitlin, author; Stone, Martha, advisor; Miller, Jeffrey, committee member; DiVerdi, Joseph, committee memberSmall-batch chocolate-makers use distinct equipment and process steps from that of large-scale industry leaders. Only one of these steps is unique to small-batch chocolate-making and is known as melanging—a refining process that takes place in a stone wet-grinder. Despite being essential to flavor and overall quality development, it has never been studied, and all data on its application to chocolate are anecdotal. This research evaluated the melanging step at three different temperatures in order to determine, via Head Space Solid Phase Micro Extraction (SPME) coupled with GC-MS, which volatile flavor-active compounds are formed or lost during the melanging process and how the time and temperature affect the volatile composition of the chocolate mass. Univariate statistical analysis on the 36 samples (3 temperatures, 4 time points, and 3 technical replicates) was performed using analysis of variance (ANOVA) and multivariate statistical analysis was performed using principal component analysis (PCA) and orthogonal partial least squares (OPLS). These analyses found that time, rather than temperature, accounted for most of the variation among samples. Some trends among chemical classes were identified, and certain indicator compounds were highlighted for their particular relevance to the system. Pyrazines displayed the strongest pattern of any annotated chemical class. As a rule, these compounds started with moderate to high abundance at 0 hours and decreased to extremely low levels by 24 hours. However, most classes of chemical compounds analyzed in this study did not follow strong patterns of behavior predicted by chemical class. Particle size and pH were also measured for each sample. Majority particle size was found to be below 25 microns generally at all time points beyond 8 hours, and pH for all samples had a mean of 5.25 with a standard deviation of 0.177. Analysis showed significant temperature-dependent p-values for several compounds, but significant time-dependent p-values were apparent for a greater number of compounds. For compounds which showed dependency on both time and temperature, the time-dependent p-value was much smaller in most cases. Both PCA and OPLS analyses suggested the same trends. It was determined first, that melanging is a viable method to carry out successful chocolate refining. The final flavor of chocolate made in a melanger is far more dependent on time spent in the melanger than on the temperature of the chocolate system. In addition, classes of chemical compounds did not behave according to unified patterns of behavior in melanging systems (with the exception of nitrogen heterocycles, which decreased in relative abundance). Finally, literature previously published on conching may be successfully extrapolated to melanging.Item Open Access Environmental fate of hydraulic fracturing fluid additives after spillage on agricultural topsoil(Colorado State University. Libraries, 2016) McLaughlin, Molly C., author; Blotevogel, Jens, advisor; Borch, Thomas, advisor; DiVerdi, Joseph, committee memberInadvertent releases of hydraulic fracturing fluid may occur at many different stages, with surface spills being the most commonly reported cause of contamination. Hydraulic fracturing (HF) frequently occurs on agricultural land, where surface spills have the potential to impact soil, groundwater and surface water quality. However, the extent of sorption, transformation, and interactions among the numerous organic HF fluid and oil & gas wastewater constituents upon environmental release is hardly known. Thus, this study aims to advance our current understanding of processes that control the environmental fate and toxicity of commonly used hydraulic fracturing chemicals with a specific focus on co-contaminant effects. Hydraulic fracturing fluid releases were simulated using aerobic batch studies conducted with a topsoil collected from Weld County, Colorado, an area where reservoirs are frequently stimulated. Each batch reactor contained varying combinations of the biocide glutaraldehyde (GA), polyethylene glycol (PEG) surfactants, and a polyacrylamide (PAM)-based friction reducer, three widely used hydraulic fracturing fluid components. Furthermore, the presence of salt was investigated in the experiments, often present at high concentration in produced water from hydraulic fracturing operations. Results showed that aqueous GA concentrations decreased by as much as 40% in the first three days of the experiment as a result of sorption to soil. Complete biodegradation of this biocide occurred in all reactors in 33 to 57 days, with the slowest removal occurring in the reactor containing salt. The fastest removal of GA was observed in the reactors containing PAM friction reducer, where degradation rates increased by 50% as compared to reactors without PAM. This increase in removal is attributed to the cross-linking reaction between GA and primary amine functional groups in the friction reducer. In the absence of GA and salt, PEG surfactants were completely biodegraded in agricultural topsoil within 42 to 71 days. Their transformation was impeded, however, in the presence of the biocide GA, and completely inhibited in the presence of 30 g/L sodium chloride, a concentration in the typical range for oil and gas wastewater. No aqueous removal of PAM was observed over a period of six months. However, adenosine triphosphate (ATP) concentrations were consistently higher in reactors containing PAM friction reducer, suggesting this additive supplied an easily accessible source of nitrogen to the microbial soil community. The findings of this study highlight the necessity to consider co-contaminant effects when we evaluate the risk of frac fluid additives and oil and gas wastewater constituents in agricultural soils in order to fully understand their human health impacts, likelihood for crop uptake, and potential for groundwater contamination.Item Open Access Life cycle environmental impacts of utilizing hemp seed meal as a protein source in sheep feedlot rations(Colorado State University. Libraries, 2023) Clark, Samantha Maye, author; Dillon, Jasmine, advisor; Archibeque, Shawn, committee member; Nachappa, Punya, committee member; DiVerdi, Joseph, committee memberHemp seed meal is a protein-rich byproduct of the hemp industry, obtained from the cold press extraction process used to produce hemp oil. The objective of this work was to evaluate the environmental impact of using hemp seed meal as a protein supplement in sheep production. A cradle-to-gate life cycle assessment (LCA) was conducted on three sheep production systems which differed in the feedlot phase: one fed a feedlot ration containing soybean meal as the protein source (soybean meal diet), one fed hemp seed meal in the feedlot ration (hemp diet), and one fed organic hemp seed meal in the feedlot ration (organic hemp diet). Animal performance data were collected from a nutrition trial. Hemp production, harvest, and processing data were provided by a hemp product company. Economic and physical allocation were applied to the hemp diet systems, and the ReCiPe Midpoint (H) methodology was used to calculate the global warming (i.e., carbon footprint), water consumption, land use, and fossil resource scarcity impacts on a per kg lamb live weight basis for each system. Carbon footprint ranged from 10.1 to 11.4 kg CO2eq/kg LW, water consumption ranged from 1.3 to 4.2 m3/kg LW, fossil resource scarcity ranged from 0.5 to 0.8 kg oil eq/kg LW, and land use ranged from 2.8 to 6 m2a crop eq/kg LW. Impact assessment results were not sensitive to a 10 or 20% increase in electricity demand at processing. The use of IPCC Tier 2 methods for estimating enteric methane emissions from sheep resulted in a 7.5–8.5% increase in the carbon footprint, relative to a mechanistic equation present in the Ruminant Nutrition System model. Physical allocation resulted in greater impacts of the hemp diet systems than the soybean diet systems for all categories except land use. However, economic allocation resulted in greater impacts for the soybean diet systems than the hemp diet systems for all categories evaluated. This was explained by inherent differences between the allocation method, as physical allocation attributed 80% of the environmental burden to hemp seed meal, while economic allocation attributed 0% of the environmental burden to hemp seed meal due to the current lack of an economic value for hemp seed meal. The production volume of dependent products ("dependent products", or products for which a change in demand does not affect production volume, commonly referred to as co- or byproducts) are driven by monetary value of the determining product (the product for which a change in demand affects the production volume), but relationships between co-products change overtime. Therefore, as the hemp industry continues to develop, an economic value may be placed on hemp seed meal with implications for its relative ability to reduce the environmental impacts of livestock production. As agricultural industries strive to become more environmentally efficient, they must be adaptive to changes in both monetary value and environmental impact, which are intrinsically related. This research demonstrated the importance of allocation choice in assessing the impact of feeding byproducts on the environmental impact of livestock production systems. Economic allocation better reflected the monetary driving factor for hemp production than physical allocation. As such, the inclusion of hemp seed meal in a feedlot ration reduced the environmental impact of sheep production systems.Item Restricted Return of the light(Colorado State University. Libraries, 2021) Lanham, Ryan, author; Fletcher, Harrison Candelaria, advisor; Langstraat, Lisa, advisor; DiVerdi, Joseph, committee memberThis book is a memoir that traces my path of healing after reaching rock bottom with an earnest suicide attempt in October 2011, one year after completing my enlistment in the Army. Each chapter, except one, begins with an italicized scene that depicts a pivotal moment of miracle, magic, synchronicity, psychic reading, or psychedelic experience. The rest of the text attempts to decode and demystify these otherworldly moments, stringing them into a sequence of events that suggests a mysterious guiding force this life.