Browsing by Author "Phetxumphou, Katherine"

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    Consumers and Their Drinking Water: Communicating Water Quality and Assessing the Reaction of Zerovalent Nanoiron (nZVI) with Saliva
    Phetxumphou, Katherine (Virginia Tech, 2014-07-01)
    Human senses for taste, odor, and visual assessment allow consumers to be selective when it comes to choosing their drinking water. In addition to wanting aesthetically pleasing water to drink, consumers want to know if their water is safe and may have misconceptions on what possible health risk contaminants could be lurking in their water supply. This thesis aimed to measure reaction of zerovalent nanoiron (nZVI) in water and human saliva, evaluate consumer's perceptions of taste, odor, and risk in their drinking water, and investigate the effectiveness of community water systems in communicating water quality information to their consumers. Since nZVI, including commercially available Nanofer 25S, is widely being used in water treatment processes and has future potential for use in fortifying foods, the exposure to these engineered nanoparticles will increase for humans and aquatic organisms. Thus, the first part of the thesis was to develop a quantitative analytical technique to measure the iron levels at environmentally relevant concentrations. Researchers developed a colorimetric assay using 1, 10-phenanthroline as an assay to determine the amount of ferrous ions produced from different iron materials, including ferrous(II)sulfate, nZVI, and goethite. Resulting ferrous ion measurements indicate that the maximum production of ferrous ions varied among the iron materials. Nanofer25S did not undergo 100% conversion to ferrous ions, as expected, goethite had no production of ferrous ions, and ferrous(II)sulfate was 100% ferrous ions. The total iron, as measured by atomic absorption for all iron materials were equal. The reactivity of these iron materials were also assessed in different water qualities ranging in salt concentrations. The capacity to produce ferrous ion did not change when added to nanopure water, tap water, and inorganic solution that is equivalent to the high ionic strength of saliva. Toxicology data for nZVI exposure to humans and aquatic organisms are limited. For that reason, authors of this manuscript measured salivary lipid oxidation (SLO) potential for the different iron materials in human saliva. They also developed an artificial saliva recipe to ensure repeatability and comparable results among laboratories due to human saliva's variability day by day. This simulated human saliva contained salts, proteins, and lipids. Using thiobarbituric acid reactive substances (TBARs), both Nanofer25S and ferrous(II)sulfate induced in-vitro SLO with human saliva. Goethite was unreactive. SLO results from this study have implications for flavor effects of nZVI in drinking water. The second chapter of this thesis is assessing the clarity of message communication of Consumer Confidence Reports (CCRs). In 1998, the United States Environmental Protection Agency (USEPA) mandated that community water systems (CWSs) provide annual water quality reports to their consumers. These CCRs summarize information regarding water sources, any detected contaminants, compliance with federal regulations, and educational information. Thirty CCRs across all ten USEPA regions were analyzed for clarity using the Centers for Disease Control and Prevention's (CDC) Clear Communication Index (CCI) tool. The analysis of these CCRs was a national representation of CWSs and revealed that currently distributed CCRs performed poorly on the CDC's CCI—all failing to meet the 90% passing mark. The overall average score for all CCRs was 50.3 ± 13.5%. The clarity scores were based on seven key areas: 1) Main message and call to action; 2) Language; 3) Information design; 4) State of the science; 5) Behavioral recommendations; 6) Numbers; and 7) Risk. Improvements in all seven areas—with the lowest average scores at 3.3 ± 18.1%, 21.7 ± 26.6%, and 37.7 ± 27.1%, respectively, for state of science, language, and main message and call to action—of the CCI will greatly improve the quality and educational capabilities of CCRs. The failing scores highlight the challenges facing CWSs in communicating water quality information. This assessment can serve as a tool for water utilities to effectively prepare and distribute information to their consumers in the future. CWSs must promote a two-way dialogue with their consumers. They should address consumer's concerns and wants in the CCRs, and they should also effectively communicate risks to the consumers so that they are not under the misconception that their water is unsafe to drink. CWSs should use the CCRs as a way to educate the public and promote drinking tap water. The last chapter of this thesis addresses the concerns that consumers may have about their drinking water and methods that could be implemented to quickly and efficiently respond to consumer complaints and contaminants with sensory properties. Just like CWSs, consumers are concerned about their water; they are the sentinels to water quality monitoring because they are uniquely positioned at the tap. Consumers are able to detect the slightest taste, odor, and appearance in their drinking water because it is well—instinctive! Thus, consumer feedback and complaint data provided to a utility should be taken seriously and stored for future comparisons. Any consumer complaint represents a fruitful data stream that should be harnessed routinely to gain knowledge about aesthetic water quality in the distribution system. Four utilities provided consumer complaints on water quality data that were categorized and visualized using radar and run-time plots. As a result, major taste, odor, and appearance patterns emerged that clarified the issue and could provide guidance to the utilities on the nature and extent of the problem. Consumer complaint data is valuable for water quality issue identification, but CWSs should understand that even though humans readily identify visual issues with water, such as color, cloudiness, or rust, describing specific tastes and particularly odors in drinking water is acknowledged to be a much more difficult task for humans to achieve without training. This was demonstrated with two utility groups, laboratory personnel and plant operators, and a group of consumers identifying the odor of orange, 2-MIB, and DMTS. All of the groups were able to identify the familiar orange odor. However, the two utility groups were much more able to identify the musty odor of 2-MIB; this may be due to the fact that the utility groups are more familiar with raw and finished water. DMTS, a garlic-onion odor associated with sulfur compounds in drinking water, was the least familiar to all three groups. The lab personnel group was the better describers of the odor, but the results within this group still varied significantly. These results suggest that utility personnel should be mindful of consumers who complain that their water is different, but cannot describe the problem. To reduce the inability to describe an odor or taste issue, a TandO program at a utility can be beneficial. The safety and aesthetic characteristics of drinking water is most important to consumers. They both complement each other; if consumers think their water tastes funny, they would probably assume that is unsafe to drink. Since nZVI is increasingly being introduced into the drinking water supply, researchers must be able to understand how it reacts in humans and the environment. Additionally, CCRs would be an effective method for CWSs to communicate water quality information and address any concerns consumers may have about their water. CWSs can use implement the radar and run-time plots to identify issues in the drinking water systems. Also, TandO programs will allow CWSs and their consumers to better describe and identify the issues in their drinking water as it arises so that it can be easily addressed and alleviated. Thus, promoting communication between water utilities and their consumers will improve the relationship and instill confidence in consumers about their drinking water.
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    The free-linking task: A graph-inspired method for generating non-disjoint similarity data with food products
    Lahne, Jacob; Phetxumphou, Katherine; Tejedor-Romero, Marino; Orden, David R. (Elsevier, 2022-01-01)
    “Free sorting”, in which subjects are asked to sort a set of items into groups of “most similar” items, is increasingly popular as a technique for profiling sets of foods. However, free sorting implies an unrealistic model of sample similarity: that similarity is purely binary (is/is not similar) and that similarity is fully transitive (similarities {A, B} and {B, C} imply {A, C}). This paper proposes a new method of rapid similarity testing—the “free-linking” task—that solves both problems: in free linking, subjects draw a similarity graph in which they connect pairs of samples with a line if they are similar, according to the subject's individual criteria. This simple task provides a more realistic model of similarity which allows degrees of similarity through the graph distance metric and does not require transitive similarity. In two pilot studies with spice blends (10 samples, 58 subjects) and chocolate bars (10 samples, 63 subjects), free linking and free sorting are evaluated and compared using DISTATIS, RVb, and the graph parameters degree, transitivity, and connectivity; subjects also indicated their preferences and ease-of-use for the tasks. In both studies, the first two dimensions of the DISTATIS consensus were highly comparable across tasks; however, free linking provided more discrimination in dimensions three and four. RVb stability was equivalent for the two methods. Graph statistics indicated that free linking had greater discrimination power: on average subjects made similarity groupings with lower degree, lower transitivity, and higher connectivity for free linking in both studies. However, subjects did overall find free sorting easier and liked it more, indicating a higher cognitive difficulty of free linking. The free-linking task, therefore, provides more robust, realistic similarity maps at the cost of higher panelist effort, and should prove a valuable alternative for rapid sensory assessment of product sets.
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    Novel Approaches to Exposure Assessment and Dose Response to Contaminants in Drinking Water and Food
    Phetxumphou, Katherine (Virginia Tech, 2018-04-23)
    In the fields of water safety, food safety, and public communications, the overarching goal is to improve public health. Thus, this dissertation focuses on risk assessment and applying novel methods for exposure assessments and dose responses to contaminants in drinking water and foods. Factors that greatly impact contaminant exposures and human dose response include: population susceptibility (i.e., healthy adults or children), different routes of exposures (i.e., ingestion or inhalation), carrier matrices (i.e., water or food), and intricacies of chemical and biological mixtures. Chemical spills, such as the 2014 crude MCHM spill in Charleston, WV, revealed the complexities of both minor and major components in the chemical mixture. Slight shifts in geometric structures (isomers) can affect the fate and transport properties of the chemical mixture and as a result, the level of human exposure and dose response to each component in the chemical mixture. Odorous properties of both minor and major components can affect human inhalation exposure, especially during showering, and can be as detrimental as the ingestion route exposure and are different for healthy adults versus for children. Food contaminants, such as Shiga toxin producing Escherichia coli (STEC) in beef products, can be mitigated through a quantitative microbial risk assessment (QMRA) framework that follows a farm-to-fork model. Methods to ensure greatest microbial reduction include: employed intervention strategies at slaughter plants (i.e., water washing of beef carcass), improved cooking times and temperature methods at the consumer and retail level, and assessed minimum effective dose response modeling for different population susceptibilities. Current public communication tools, including the Drinking Water Taste-and-Odor Wheel or Consumer Confidence Reports (better known as water quality reports), should be redeveloped to uphold water safety. Furthermore, public health campaigns that uses social media strategies and informative websites can better educate the public on food contaminants. Ultimately, the objective is to prevent human illnesses due to water contaminants and foodborne pathogens and to bridge the communication gap between the consumers and the experts concerned with water and food safety.
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    Processing Condition Effects on Sensory Profiles of Kombucha through Sensory Descriptive Analysis
    Phetxumphou, Katherine; Vick, Rebecca; Blanc, Lori A.; Lahne, Jacob (2022-02-09)
    Kombucha is a fermented and often sweetened tea beverage that has become increasingly popular in the U.S. in the last decade. While it is often infused with fruits and vegetables to enhance aroma and flavor, unflavored kombucha itself has distinctive sensory attributes influenced by multiple factors, including initial tea type, initial sugar concentration, and fermentation temperature. How these different factors affect the final aroma and flavor of kombucha has been underexplored in the scientific literature. In this study, processing treatments, including tea type (black and green), sugar concentration (63 g/L and 94 g/L), and fermentation temperature (21 °C and 25.5 °C) were combined in a factorial design to produce experimental kombucha (K = 8). Panelists (N = 7) completed a full sensory Descriptive Analysis (DA) evaluation of the experimental kombucha, in which they defined 63 sensory attributes. MANOVA identified 43 sensory attributes that differed among the samples due to tea type, initial sugar concentration, and fermentation temperature, although surprisingly tea, sugar, and temperature did not interact significantly. Overall, teas fermented at a lower temperature or with higher sugar were sweeter, thicker, and associated with fruit-related aromatics; teas fermented at a higher temperature and with less sugar were associated with fermented, vegetal, and yeasty aromas, fizzy mouthfeels, and sour and bitter tastes. Surprisingly, tea type played only a weak role in final kombucha flavor.