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<div><div><div><p>Interfacial rheology describes the functional relationship between the deformation of an interface, the stresses exerted in and on it, and the resulting flows in the adjacent fluid phases. These interfacial properties are purported to influence emulsion stability. Protein emulsifiers tend to adsorb to the interface of immiscible phases, reduce interfacial tension as well as generate repulsive interactions. A magnetic interfacial shear rheometer was used to characterize the surface pressure-area isotherms as well as interfacial rheological properties of two proteins- sodium caseinate and b-lactoglobulin. Then, sodium caseinate was used as a carrier for b-carotene encapsulation.</p><p>b-carotene is a carotenoid that exhibits pro-vitamin A activity, antioxidant capacity and is widely used as a food colorant. It is however, highly hydrophobic and sensitive to heat, oxygen and light exposure. Thus b-carotene as food ingredient is mainly available as purified crystals or as oil-in-water emulsions. In this study, b-carotene stability, and solubility in water for application as a natural colorant was improved by preparation of a sodium caseinate/ b-carotene powder using high pressure homogenization, solvent evaporation and spray drying. The powders thus prepared showed good solubility in water and yielded an orange coloration from b-carotene. The effect of medium chain triglyceride concentration (1%, 10%) and incorporation of a natural antioxidant (Duralox, Kalsec) on powder stability was studied as a function of storage time and temperature.b-carotene stability was reduced at higher storage temperature (4oC> 21oC> 50oC) over 60 days and followed first order degradation kinetics at all temperatures. Incorporation of natural antioxidant improved b-carotene stability and resulted in a second first order degradation period at 50oC. As b-carotene content decreased, Hunter Lab color values denoting lightness increased, while those for redness and yellowness of the powder decreased. This sodium caseinate based b-carotene powder could be used as a food ingredient to deliver natural b-carotene to primarily aqueous food formulations.</p><div><div><div><p>In the last part of this work, an engagement workshop was developed as a means to educate young consumers about the function of emulsifiers in foods. Food additives are important for food product development, however to consumers, a discord between their objective purpose and subjective quality has led to confusion. Food emulsifiers, in particular, are associated with lower healthiness perception due to their unfamiliar names. In collaboration with the 4H Academy at Purdue, a workshop high school student was conducted to develop an increased understanding of emulsions and emulsifiers. A survey was conducted with the participants who self-evaluated their gain in knowledge and tendency to perform certain behaviors with regards to food ingredient labels. The participants reported a gain in knowledge in response to four key questions on emulsions and emulsifiers, as well as an increased likelihood to read ingredients on a food label and look up information on unfamiliar ingredients.</p></div></div></div></div></div></div>

Environmental factors such as diet contribute to the pathogenesis of inflammatory bowel disease (IBD). Epidemiological evidence suggests a robust linkage between IBD and the Western diet, which is often characterized by a high intake of food additives. These additives, including synthetic colourants, are widely used, leading to significant human exposure. Allura Red AC (AR) is one of the most popular synthetic colourants, yet little is known about its impact on human health and the role of AR in the pathogenesis of colitis remains elusive. Serotonin (5-hydroxytryptamine; 5-HT), which regulates various gut physiological processes, has been shown to modulate the gut microbiota and enhance susceptibility to colitis. In this thesis, it was discovered that chronic exposure to AR, at a dose found in commonly consumed dietary products, exacerbated dextran sulfate sodium (DSS)-induced colitis and triggered early onset of disease in the CD4+CD45RBhigh T cell-induced colitis model. AR also induced low grade colonic inflammation in naïve C57BL/6 mice. Exposure to AR was associated with increased colonic 5-HT levels and impaired intestinal barrier function via activation of the myosin light chain kinase (MLCK) pathway. However, AR did not promote colitis in mice lacking tryptophan hydroxylase 1 (Tph1), the rate-limiting enzyme responsible for colonic 5-HT synthesis. Further, AR increased colonic 5-HT levels in germ-free (GF) mice and perturbed the gut microbiota composition in specific pathogen-free (SPF) mice. Transfer of this altered microbiota from the dye-exposed SPF mice to GF mice conferred enhanced susceptibility to DSS-induced colitis. Mechanistically, AR induced reactive oxygen species (ROS) generation and promoted 5-HT secretion via the NF-κB pathway in BON cells. Data in this thesis indicate that the widely used synthetic colourant, AR, promotes colitis via colonic 5-HT in microbiota-dependent and -independent pathways. Collectively, these findings provide important information on enhancing public awareness of its detrimental effects on human health. / Thesis / Candidate in Philosophy / Epidemiological and experimental studies suggest a potential link between inflammatory bowel disease (IBD) and diet. The Western diet, often characterized by a high intake of processed foods, is associated with the growing incidence of IBD. Allura Red AC (AR) is a popular artificial food dye found in highly common processed foods, yet little is known about its impact on human health and disease. Serotonin, a key molecule in the gut, has been implicated in large bowel inflammation. Herein, the potential role of AR in the development of colitis was examined. Across multiple models, AR exposure heightened vulnerability to colitis in mice, an effect attenuated by reduced serotonin production in the gut. The effect of AR in enhancing colitis vulnerability occurred via gut microbiota-dependent and -independent pathways. These studies have identified how AR promotes colitis, findings that may advance public health awareness and impact the health of patients with IBD.