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theses

Functional beverages, usually fortified with nutraceuticals in addition to flavors, can provide specific health benefits beyond the refreshing tastes. The general scope of the current study was to develop a functional beverage prototype infused with citral and coenzyme Q10 (CoQ10). Citral, one of the most popular flavors with strong lemon aroma, has the problem of being easily degraded and oxidized in the acidic beverage applications. And CoQ10, a lipophilic nutraceutical with health benefits for cardiovascular diseases and energy-boosting, has rather low bioavailability in common supplements. Therefore, our specific objectives were to improve both citral's stability and CoQ10's bioavailability in the developed functional beverages by using nanoemulsion-based delivery systems. For citral stability studies, our results suggested that its chemical stability can be greatly improved with proper selection of antioxidants and emulsifiers in the nanoemulsion systems. The reduced form of CoQ10, known as ubiquinol or Q10H2, proved to be effective as a potent antioxidant in protecting citral from degradation during storage when its concentration was optimized at 0.10 wt% (Q10H2/citral ratio of 1:1). Moreover, the effects of different emulsifiers in stabilizing citral were further examined. In detail, two synthetic surfactants (polysorbate, sugar ester), and three natural emulsifiers (saponin, lecithin, and lyso-lecithin) were tested and compared. Results indicated saponin (i.e. Q-Naturale) and lyso-lecithin (i.e. LPC20) had significantly improved effects in protecting citral from degradation and inhibiting the generation of the major off-flavors (p-cresol, α,p-dimethylstyrene, p-methylacetophenone). To access CoQ10 bioavailability, both in vitro and in vivo tests were performed with our optimized nanoemulsion formulation and an oil dispersion control. Based on the promising bioaccessibility results indicated by two in vitro digestion models (pH-stat lipolysis model & TNO gastrointestinal model - TIM-1), CoQ10's pharmacokinetics and tissue distributions after ingestion were further examined using animal models. Results of pharmacokinetics revealed a 2.65-folds increase for the area under curve (AUC) of CoQ10 in our nanoemulsion group compared with the control, indicating the oral bioavailability of CoQ10 was significantly improved. A characteristic "two-peak" pattern was observed in the concentration-time curves, suggesting CoQ10's relatively slow absorption kinetics and the possible effect of enterohepatic recycling. Moreover, CoQ10's tissue distribution data further proved its increased absorption and uptake levels in major organs tissues after dosing with the nanoemulsion. In conclusion, our developed nanoemulsion formulation greatly improved citral stability and CoQ10 bioavailability. The obtained results will be valuable references for the food industry to formulate and develop functional beverages fortified with lipophilic nutraceuticals and sensitive flavors.

ETD_7616

Ph.D.

Includes bibliographical references

by Qin Zhao

doi:10.7282/T3RX9FDD

ETD doctoral

The author owns the copyright to this work.