Doctoral Dissertations

Date of Award

5-2019

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Food Science

Major Professor

Qixin Zhong

Committee Members

Guoxun Chen, Vermont P. Dia, Doris D'Souza

Abstract

Delivery of vitamin D3 (VD3) in foods should exhibit desirable physicochemical characteristics and enhance nutritional significance. To incorporate lipophilic VD3 in beverages, micro/nanoencapsulation of VD in food biopolymers stable at a wide pH range is a potential strategy. Gum arabic (GA), a highly branched arabinogalactan with a conjugated peptide, was investigated as a potential VD3 carrier in this dissertation with objectives to determine (1) optimum conditions of encapsulating VD3 in GA to maximize loading and characterize physicochemical properties, (2) in vitro bioaccessibility of encapsulated VD3 in optimized formulation, and (3) absorption of VD3 after a single high-dose (300 μg) and daily-dose (60 μg d-1, 2-wks) oral supplementation by measuring 25(OH)D levels in Sprague-Dawley rats. To encapsulate VD3, GA solution was prepared at 5% (w/v) in deionized water, VD3 solutions were prepared separately in 5 mL ethanol corresponding to 0.03-6.0% mass of GA. VD3 solution was added dropwise into 50 mL of the GA solution while blending at 8,000 rpm for 3 min and then 10,000 rpm for 2 min and freeze-dried. The optimized formulation had an encapsulation efficiency of 71.3% and a loading capacity of 3.44%. As pH increased from 2.0-7.4, the average hydrodynamic diameter decreased from 238.1 to 81.3 nm; whereas the polydispersity index increased from 0.372-0.478, and zeta-potential increased its magnitude from -3.09 to -30.97 mV. No precipitation was observed for all dispersions during 100-d storage at 3 °C. In vitro bioaccessibility of encapsulated VD3 was 95.76%, compared to 68.98% for non-encapsulated VD3 (p < 0.05). The in vivo pharmacokinetic study after oral gavage of 300 μg VD3 showed that the area-under-curve in 48 h of the encapsulation treatment was 4.32-fold of the non-encapsulated VD3 and more than twice higher than the physical mixture. For rats given a daily-dose of 60 μg VD3 d-1 for 2 weeks, the serum 25(OH)D levels of rats that received capsules versus physical mixture showed an increase by 50% and 65%, respectively, when compared with the non-encapsulated VD3 group. The current work demonstrates that the studied encapsulation system may be used to fortify VD3 in beverages with a wide pH range.

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