Physical State of β-Carotene at High Concentrations in a Solid Triglyceride Matrix

TY - JOUR

T1 - Physical State of β-Carotene at High Concentrations in a Solid Triglyceride Matrix

AU - Schjoerring-Thyssen, Jakob

AU - Olsen, Karsten

AU - Koehler, Klaus

AU - Jouenne, Eric

AU - Larsen, Flemming Hofmann

AU - Andersen, Mogens L.

PY - 2020/2/1

Y1 - 2020/2/1

N2 - The highly hydrophobic β-carotene is often distributed or dissolved in triglycerides to enhance either nutritional or coloring effects. This study aims at elucidating the physical state of β-carotene that at high concentrations are mixed into a solid high-melting tri-glyceride matrix by dissolution at high temperatures (165 °C) in the melted triglyceride. Extensive isomerization of β-carotene is observed by HPLC after melting crystalline all-trans β-carotene and in the solid mixtures of β-carotene and fully hydrogenated sunflower oil. Crystalline triglyceride is found in the mixed samples by XRPD analysis whereas no signs of crystalline lattice structures of β-carotene are detected. DSC thermograms show only the melting and recrystallization events of triglycerides, which are affected by the presence of β-carotene. Severe line broadening is observed in the 13C CP/MAS NMR spectra of the β-carotene-triglyceride mixtures when compared to crystalline β-carotene, demonstrating the lack of long-range order of the carotene. Altogether, the results demonstrate that β-carotene is present as an amorphous mixture of trans- and cis-isomers dispersed into a structure of crystalline triglyceride in the solid carotene-triglyceride mixtures. Practical applications: The amorphous structure of trans- and cis-isomers in solid formulations of β-carotene-triglyceride mixtures will strongly affect their functional properties related to nutrition and color as food ingredients.

AB - The highly hydrophobic β-carotene is often distributed or dissolved in triglycerides to enhance either nutritional or coloring effects. This study aims at elucidating the physical state of β-carotene that at high concentrations are mixed into a solid high-melting tri-glyceride matrix by dissolution at high temperatures (165 °C) in the melted triglyceride. Extensive isomerization of β-carotene is observed by HPLC after melting crystalline all-trans β-carotene and in the solid mixtures of β-carotene and fully hydrogenated sunflower oil. Crystalline triglyceride is found in the mixed samples by XRPD analysis whereas no signs of crystalline lattice structures of β-carotene are detected. DSC thermograms show only the melting and recrystallization events of triglycerides, which are affected by the presence of β-carotene. Severe line broadening is observed in the 13C CP/MAS NMR spectra of the β-carotene-triglyceride mixtures when compared to crystalline β-carotene, demonstrating the lack of long-range order of the carotene. Altogether, the results demonstrate that β-carotene is present as an amorphous mixture of trans- and cis-isomers dispersed into a structure of crystalline triglyceride in the solid carotene-triglyceride mixtures. Practical applications: The amorphous structure of trans- and cis-isomers in solid formulations of β-carotene-triglyceride mixtures will strongly affect their functional properties related to nutrition and color as food ingredients.

KW - amorphous

KW - cis-trans isomerization

KW - triglycerides

KW - X-ray diffraction

KW - beta-carotene

U2 - 10.1002/ejlt.201900250

DO - 10.1002/ejlt.201900250

M3 - Journal article

SN - 1438-7697

JO - European Journal of Lipid Science and Technology

JF - European Journal of Lipid Science and Technology

M1 - 1900250

ER -