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Consumer interest in supplementation with healthy omega-3 fatty acids (Ï 3 FA) has led to increased research in fortification of popular foods with these healthy fats. Yogurt, which is already popular, offers a functional food matrix to fortify with Ï 3 FA. Fish oil, a major source of two important long chain Ï 3 FA eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) is an excellent source of Ï 3 FA enrichment into foods but brings problems of oxidation and off-flavors or odors when added to foods. Encapsulation, deodorized fish oil, and flavoring have been investigated to reduce these off-flavors and odors in food products while producing a fish oil-fortified yogurt. Discrimination of butter, fish or oxidized fish oil at 0.5% (wt/wt) levels was investigated in unflavored low-fat (1%) yogurt using untrained panelists (n=31) and sensory triangle tests. Five sensory attributes (lime, sweet, heat, acid, oxidized) were analyzed by experienced sensory panelists (n=12) in chile-lime flavored yogurts with butter, fish or oxidized fish oils added at low (0.43%) and high (1% wt/wt) levels. Analytical analysis for composition, fatty acid profile, and volatile chemistry of the yogurts was conducted. Consumer acceptance of a low-fat (1.5%) chile-lime flavored yogurt enriched with fish oil was investigated using a 9-point hedonic scale (1="dislike extremely", 9="like extremely"). Untrained panelists (n=31) were unable to differentiate 0.5% (wt/wt) levels of fish and butter oils in unflavored yogurts but were able to detect oxidized fish oil compared to butter or fish oil under in the same conditions. Experienced panelists (n=12) found significant differences (p<0.05) in lime and acid attributes in chile-lime flavored yogurts containing 1% (wt/wt) oxidized fish oil compared with 0.43 and 1% (wt/wt) butter and fish oil yogurts and 0.43% (wt/wt) oxidized fish oil yogurts. Oxidized attributes were determined as significantly different (p<0.05) by experienced panelists in chile-lime yogurts with 1% (wt/wt) fish oil, 0.43 and 1% (wt/wt) oxidized fish oil added. The acceptance of a fish oil-enriched chile-lime flavored yogurt was neutral ("neither liked nor disliked") by consumers (n=100) but 44% rated the product "like slightly" (6 of 9) or greater. A successful chile-lime flavored yogurt offering a novel savory flavor was formulated from pre-pasteurization addition of fish oil to deliver more than 145 mg DHA+EPA/170 g serving of yogurt. / Master of Science

Active lipid metabolism is a key process required for the intra-erythrocytic development of the malaria parasite, Plasmodium falciparum. Enzymes that hydrolyze host-derived lipids play key roles in parasite growth, virulence, differentiation, cell-signaling and hemozoin formation. Therefore, investigating enzymes involved in lipid degradation could uncover novel drug targets. We have identified in P. falciparum, a glycerophosphodiester phosphodiesterase (PfGDPD), involved in the downstream pathway of phosphatidylcholine degradation. PfGDPD hydrolyzes deacylated phospholipids, glycerophosphodiesters to glycerol-3-phosphate and choline. In this study, we have characterized PfGDPD using bioinformatics, biochemical and genetic approaches. Knockout experiments showed a requirement for PfGDPD for parasite survival. Sequence analysis revealed PfGDPD possesses the unique GDPD insertion domain sharing a cluster of conserved residues present in other GDPD homologues. We generated yellow fluorescent fusion proteins that revealed a complex distribution of PfGDPD within the parasite cytosol, parasitophorous vacuole and food vacuole. To gain insight into the role of PfGDPD, sub-cellular localization was modulated and resulted in a shift in protein distribution, which elicited no growth phenotype. Kinetic analyses suggest PfGDPD activity is Mg₂⁺ dependent and catalytically efficient at the neutral pH environment of the parasitophorous vacuole. Next, our aim was to determine the upstream pathway that provides deacylated glycerophosphodiesters as substrate for PfGDPD. We identified via bioinformatics, a P. falciparum lysophospholipase (PfLPL1) that directly generates the substrate. Knockout clones were generated and genotyped by Southern and PCR analysis. The effects of PfLPL1 knockouts on parasite fitness were studied, and the results showed that PfLPL1was not required for parasite survival and proliferation. / Ph. D.

Milk is often packaged in translucent containers providing little protection against flavor degradation from light. Addition of omega-3 fatty acid sources into milk increases the risk of light-initiated degradation of nutrients and sensory quality. The effectiveness of iridescent film materials in reducing light-induced oxidation of extended shelf-life omega-3 fatty acid enriched milk (2% total fat) was studied. Film selections were targeted to provide product visibility and control product exposure at targeted riboflavin excitation wavelength regions. Effectiveness was determined by sensory evaluation and measuring changes in volatile compounds on days 1, 7, 14, and 21 when stored under fluorescent light at 4°C. Five packaging treatments (films overwrapped on glass bottles) were evaluated: 446nm block, 570 nm block, broad spectrum block with 4% transmission (BS4T), light-protected (foil overwrap) control, and light-exposed (no overwrap) control. Experienced panelists (n=12) rated oxidized flavor intensity (0-9; 9=extreme) for milk samples. Light-protected milk was lower in oxidized flavor (mean score less than 3) throughout the storage period. Oxidized flavor in milk with BS4T film overwraps was not different compared to light-protected milk (p>.05) at the later stage (21 days), suggesting some level of protection to milk flavor. Milk without fish oil (milk fat only) shows relatively larger peak areas for 2-butanone on day 14, compared to other milk samples, suggesting antioxidants in the fish oil can prevent light oxidation. Overall, packaging that provides a complete light block is still the best way to prevent light-oxidized flavor in milk. / Master of Science in Life Sciences

Pacific bluefin tuna (PBT; Thunnus orientalis) has grown significantly in popularity in recent years due to the globalization of Japanese cuisine. PBT is highly sought after for sushi and sashimi products due to its great quality and taste. Wild populations of this species have been affected by their increasing popularity, pushing innovators in the food industry to create meat alternative versions of PBT. The muscle composition of PBT varies, leading to different types (cuts) of meat in a way that is analogous to various cuts of beef. This study evaluated the differentiation amongst the 6 distinct cuts, including otoro, ventral akami, dorsal akami, ventral chu-toro, dorsal chu-toro, and wakaremi conducting volatile analysis, proximate analysis, and fatty acid analysis. The results from these analyses can then be used as a base standard for companies seeking to create alternatives versions of PBT. Samples analyzed in this study were cultured PBT species that were caught as juveniles and raised in captivity on a PBT farm in Mexico. Volatile analysis was conducted using a SPME GC/MS method. Overall, 41 aroma compounds were identified in PBT that met the identification criteria, including 9 aldehydes, 7 alcohols, 14 alkanes, 2 ketones, 4 alkenes, 3 aromatic compounds, and 2 miscellaneous compounds. Proximate analyses were conducted using standard methods. Significant differences (p <0.05) were found between each cut for the proximate analysis. The fatty acid analysis determined that there were twenty-two identifiable fatty acids found in the different cuts. The omega-3 fatty acids eicosapentaenoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3) with DHA being present at a higher amount than EPA in each cut. Overall, there are similarities and differences among the different cuts of bluefin tuna that researchers would need to mimic to provide adequate nutritional and sensorial properties of PBT. / Master of Science in Life Sciences / Pacific bluefin tuna (PBT; Thunnus orientalis) is a fish that has gained tremendous popularity over the years due to the globalization of Japanese cuisine. This tuna species is synonymous with high quality and great taste, making it key for sushi and sashimi dishes. The increased demand for this species has caused wild populations to decrease; therefore, the food industry has sought to create meat alternatives for the species. The PBT has 6 distinct cuts that make up the composition of the fish, similar to the differences that can be found in beef cuts. These 6 distinct cuts are otoro, ventral akami, dorsal akami, ventral chu-toro, dorsal chu-toro, and wakaremi. The purpose of this study is to determine the aroma composition, fatty acid composition, and fat, moisture, ash, and protein contents of the different cuts. To measure the aroma composition, gas-chromatography mass spectroscopy (GC-MS) was used; it is a machine that can be used to identify and measure the aroma compounds of products. Standard procedures were used for the other analyses. Overall, 41 aroma compounds were identified in PBT that met the identification criteria, consisting of aldehydes, alcohols, alkanes, ketones, alkenes, aromatic compounds, and some miscellaneous compounds. The cuts displayed distinguishable differences in their fat, ash, moisture, and protein contents. The fatty acid analysis concluded that there were twenty-two identifiable fatty acids found in the different cuts. In this study, close attention was paid to omega-3 fatty acids due to their health benefits for consumers. The omega-3 fatty acids eicosapentaenoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3) were found in all cuts with DHA being present at a higher amount than EPA in each cut. From this study, researchers have the foundation for understanding the composition of PBT to create a meat alternative that meets consumer expectations.

Dairy products are a primary source of c9, t11-CLA, an anti-carcinogenic agent, in the diet of humans. The t10, c12-CLA isomer, typically in trace amounts in bovine milk fat, also may benefit human health. Four cows received abomasal infusions of c9, t11-CLA or t10, c12-CLA to obtain milk fat used to prepare butter and yogurt with enhanced c9, t11-CLA or t10, c12-CLA content. Human subjects (3 males, 3 females, ages 22 to 29) received CLA-enhanced butter and yogurt (14% of total kcal) in a crossover study with 2-wk periods. Prior to the study (2 wk) and during a 2-wk washout period between the experimental periods, subjects received butter and yogurt without enhanced CLA content. Blood samples were obtained at 0, 2, 4, 6, and 8 wk relative to the start of the first experimental period. The t10, c12- CLA isomer was detected in plasma (1.32 ug/mL) only when dairy products with enhanced t10, c12-CLA was consumed. Baseline c9, t11-CLA was 6.94 ug/mL plasma during control periods, but increased to 8.95 ug/mL when dairy products with enhanced c9, t11-CLA content were consumed. Results indicated concentrations of CLA isomers in human plasma respond to small changes in daily intake of the isomers in dietary sources. / Master of Science