Theses & Dissertations

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    Influence of immersion in a space-like environment on taste and odour perception
    (University of Guelph, ) Tran, Alicia; Duizer, Lisa
    Existing literature suggests that environmental factors (i.e., sound and smell) may contribute to a change in sensory perception of food eaten in space, however, this has yet to be fully investigated. To explore the effects of environmental space-like conditions on taste and odour perception, two studies were conducted. The first study investigated the effect of environmental International Space Station (ISS) sounds played through headphones on intensity of the five basic tastes. The second study immersion in a space-like environment on odour perception and emotional responses. Results showed that environmental ISS sounds of 70 dB had no effect on taste perception, and odour perception and emotional responses may be influenced by different odours and light conditions. Further studies must be performed under more representative conditions and with more dynamic food systems to fully characterize the effect of environmental factors on perception of taste and odour in space.
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    Self-Assembly of Halogenated 1,3:2,4-Dibenzylidene-D-Sorbitol (DBS)
    (University of Guelph, ) Bai, Yuchen; Rogers, Michael
    1,3:2,4-Dibenzylidene-D-sorbitol (DBS) gels a wide array of organic solvents due to its distinctive molecular structure, allowing molecules to self-assemble via non-covalent interactions. The hydroxyl groups allow hydrogen bonding, and the benzylidene groups enable π-π stacking to drive DBS self-assembled fibrillar network (SAFiN) formation. Thus, modifying the molecular groups of DBS may alter self-assembly. This study examines the role of halogen and hydrogen bonding on the self-assembly of DBS that is modified by replacing the sn-6 hydroxyl group with a halogen, either chlorine (Cl), bromine (Br), or iodine (I). Replacing the primary hydroxyl group with a halogen on DBS weakens hydrogen bonding potential but introduces a halogen bonding site, drastically altering the gelation and the SAFiN.
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    Structured Edible Oils: The Potential of Mixed Cyclic Di-Amino Acids
    (University of Guelph, ) Sultani, Arianna; Rogers, Michael
    Cyclic di-amino acids (CdAAs) are versatile low molecular-mass organogelators (LMOGs) investigated across multiple applications, including oil structuring and improving drug delivery. The gelling behavior, and crystal morphology compared for induvial and mixed CdAAs in various solvents found mixtures of four or more CdAAs altered gelation allowing it to form a colloidal, protein crystal network in canola oil, while individual CdAA gelators precipitated. Combining CdAAs alters the gelation behavior of the mixed CdAA gels compared to pure CdAA gels. Self-assembly of a single CdAA is influenced by identical amino acid side chains driving molecular alignment. Mixed CdAA systems are directed to self-assemble based on their cyclic ring, and with sufficient amino acid side chain diversity, highly branched colloidal protein crystal form, solidifying canola oil. The crystalline networks formed by the mixed CdAAs are similar to traditional fat crystal networks, making mixed CdAAs an excellent candidate as a novel fat structuring agent.
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    A study on the efficacy of hydroxyl-radical interventions to decontaminate raw poultry meat inoculated with salmonella and campylobacter
    (University of Guelph, ) Camacho-Martinez, Silvia Vanessa; Warriner, Keith
    Most cases of foodborne illness caused by Salmonella and Campylobacter have been attributed to poultry meat. Both pathogens can be acquired and disseminated during processing. The thesis was directed towards the development, validation, and verification of interventions based on the hydroxyl-radical process. A range of methods were evaluated: Photo-Fenton (activated water), Peroxone (ozone and hydrogen peroxide), Microwave Discharge Lamp and Gas-phase Hydroxyl-radical Process (hydrogen peroxide mist, ozone gas and UV-C). All tested treatments supported 1 log CFU reduction of Salmonella. Evidence suggested that the meat surface provided protective sites that limited the efficacy of the treatment. The optimal gas phase-hydroxyl radical process was 1% v/v hydrogen peroxide, UV-C dose of 112 mJ/cm2 and 12 ppm ozone in a 30s treatment. When applied to naturally contaminated meat the carriage of Salmonella and Campylobacter were both reduced by 8% using RT-PCR as the diagnostic platform. The gas phase hydroxyl-radical process represents a preventive control that can be applied in poultry processing.
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    Development of Betalain-Based Colorimetric Indicator Systems for the Detection of Volatile Amines
    (University of Guelph, ) Levac, Brock; Lim, Loong-Tak
    Betalains, a group of naturally occurring compounds that grant coloration to some plants and fruits, are water-soluble and nitrogen containing. Categorized into betacyanins (violet) and betaxanthins (yellow), these compounds are best known for their many favourable characteristics including their stability, antioxidancy, and wide range of color properties. This research aims to explore the potential application of betalains as colorimetric indicators. Betanin, responsible for beetroot's color, serves as a dye, integrated into an ink, and printed via piezoelectric inkjet. A second cartridge was filled with a colourless acidic solution and printed in combination with the betanin ink for the fabrication of four 4 × 4 cm indicators. Additionally, synthesized betalain derivatives are investigated, successfully producing pyrrolidine-betaxanthin which showed to have a maximum fluorescence emission at 513 nm. The study highlights betalains' promise as color indicators, paving the way for their application in the food and chemical industries.