Green tea extract as food antioxidant. Synergism and antagonism with a-tocopherol in vegetable oils and their colloidal systems.

TY - JOUR

T1 - Green tea extract as food antioxidant. Synergism and antagonism with a-tocopherol in vegetable oils and their colloidal systems.

AU - Yin, Jie

AU - Miquel Becker, Eleonor-Carmen

AU - Andersen, Mogens Larsen

AU - Skibsted, Leif Horsfelt

PY - 2012/12/15

Y1 - 2012/12/15

N2 - The antioxidant effects of α-tocopherol (TOH) in combination with green tea extract (GTE), the green tea polyphenol (-)-epicatechin (EC) or the isomeric (+)-catechin (C), were investigated using different lipid systems based on high linoleic sunflower oil: bulk oil, o/w-emulsion and a phosphatidylcholine-based liposome system. Both polyphenols as well as TOH were efficient antioxidants in all systems when used alone, as detected by the formation of free radicals and conjugated dienes and by oxygen consumption. Strong synergistic effect was found for the combination of TOH and GTE in a methyl linoleate o/w-emulsion and in the pure bulk oil, while only an additive effect was observed in a liposome system. The synergism was already evident for the tendency for radical formation in the bulk oil as detected by electron spin resonance (ESR) spectroscopy. On the contrary, combinations of TOH with either EC or C showed clear synergistic effects in both heterogeneous systems, but antagonistic or additive effects in bulk oil. GTE may accordingly be used to protect both vegetable oils and their emulsions against oxidation through enhancement of the activity of their endogenous antioxidants, while GTE is less efficient in the protection of phospholipids as in liposomes.

AB - The antioxidant effects of α-tocopherol (TOH) in combination with green tea extract (GTE), the green tea polyphenol (-)-epicatechin (EC) or the isomeric (+)-catechin (C), were investigated using different lipid systems based on high linoleic sunflower oil: bulk oil, o/w-emulsion and a phosphatidylcholine-based liposome system. Both polyphenols as well as TOH were efficient antioxidants in all systems when used alone, as detected by the formation of free radicals and conjugated dienes and by oxygen consumption. Strong synergistic effect was found for the combination of TOH and GTE in a methyl linoleate o/w-emulsion and in the pure bulk oil, while only an additive effect was observed in a liposome system. The synergism was already evident for the tendency for radical formation in the bulk oil as detected by electron spin resonance (ESR) spectroscopy. On the contrary, combinations of TOH with either EC or C showed clear synergistic effects in both heterogeneous systems, but antagonistic or additive effects in bulk oil. GTE may accordingly be used to protect both vegetable oils and their emulsions against oxidation through enhancement of the activity of their endogenous antioxidants, while GTE is less efficient in the protection of phospholipids as in liposomes.

U2 - 10.1016/j.foodchem.2012.07.025

DO - 10.1016/j.foodchem.2012.07.025

M3 - Journal article

C2 - 22980790

SN - 0308-8146

VL - 135

SP - 2195

EP - 2202

JO - Food Chemistry

JF - Food Chemistry

IS - 4

ER -