title: Fluorescence imaging of spatial location of lipids and proteins during digestion of protein-stabilized oil-in-water emulsions: A simulated gastrointestinal tract study.
abstract: A whey protein isolate-rhodamine B conjugate (WPI-RB) was synthesized to visualize changes in the location of a protein emulsifier in oil-in-water emulsions during digestion. An oil-soluble dye (Nile Red) was used to visualize changes in the lipid phase during digestion. Protein-labeled and lipid-labeled emulsions were passed through a simulated gastrointestinal tract consisting of mouth, stomach, and intestinal phases, and changes in protein and lipid location and morphology were monitored using confocal laser scanning microscopy. The proteins remained attached to the lipid droplet surfaces in the mouth and stomach, but formed large aggregates in the small intestine. The lipid droplets were highly flocculated in the mouth, highly coalesced in the stomach, and fully digested in the small intestine. Our results show that conjugation of fluorescence dyes to protein emulsifiers is useful for direct visualization of their location, as well as for understanding the behavior of food emulsions within the gastrointestinal tract.
authors.affiliation: Research Institute for Agriculture and Life Science, Center for Food and Bioconvergence, and Department of Biosystems and Biomaterials Science and Engineering, Seoul National University, Seoul 08826, Republic of Korea.
authors.forename: Saehun
authors.initials: S
authors.lastname: Mun
authors.affiliation: Molecular Imaging and Therapy Branch, National Cancer Center, 111 Jungbalsan-ro, Ilsandong-gu, Goyang, Gyeonggi-do 10408, Republic of Korea.
authors.forename: Jisu
authors.initials: J
authors.lastname: Kim
authors.affiliation: Department of Food Science, University of Massachusetts, Amherst, MA 01003, United States; Department of Biochemistry, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah 21589, Saudi Arabia.
authors.forename: David Julian
authors.initials: DJ
authors.lastname: McClements
authors.affiliation: Research Institute for Agriculture and Life Science, Center for Food and Bioconvergence, and Department of Biosystems and Biomaterials Science and Engineering, Seoul National University, Seoul 08826, Republic of Korea. Electronic address: yongro@snu.ac.kr.
authors.forename: Yong-Ro
authors.initials: YR
authors.lastname: Kim
authors.affiliation: Molecular Imaging and Therapy Branch, National Cancer Center, 111 Jungbalsan-ro, Ilsandong-gu, Goyang, Gyeonggi-do 10408, Republic of Korea. Electronic address: ydchoi@ncc.re.kr.
authors.forename: Yongdoo
authors.initials: Y
authors.lastname: Choi
mesh_terms: D004655:Emulsions / Q000737:chemistry*; D005453:Fluorescence; D041981:Gastrointestinal Tract / Q000737:chemistry*; D008055:Lipids / Q000737:chemistry*; D000067816:Whey Proteins / Q000737:chemistry*
chemical_list: D004655:Emulsions; D008055:Lipids; D000067816:Whey Proteins
keywords: Confocal laser scanning microscopy; Emulsions; Fluorescent dye-conjugated protein; Interfacial properties; Lipid digestion