Volatile composition of sunflower oil-in-water emulsions during initial lipid oxidation: influence of pH.
The formation of odor active compounds resulting from initial lipid oxidation in sunflower oil-in-water emulsions was examined during storage at 60 degrees C. The emulsions differed in initial pH, that is, pH 3 and 6. The volatile compounds were isolated under mouth conditions and were analyzed by gas chromatography/sniffing port analysis. The lipid oxidation rate was followed by the formation of conjugated hydroperoxide dienes and headspace hexanal. The initial pH affected the lipid oxidation rate in the emulsions: the formation of conjugated diene hydroperoxides and the hexanal concentration in the static headspace were increased at pH 6. Pentanal, hexanal, 3-pentanol, and 1-octen-3-one showed odor activity in the emulsions after 6 days of storage, for both pH 3 and 6. Larger amounts of odor active compounds were released from the pH 6 emulsion with extended storage. It was shown that this increased release at pH 6 was not due to increased volatility because an increase in pH diminished the static headspace concentrations of added compounds in emulsions.
van Ruth
S M
SM
Department of Food Technology, Wageningen Agricultural University, 6700 EV Wageningen, The Netherlands.
Roozen
J P
JP
Posthumus
M A
MA
Jansen
F J
FJ
D004655:Emulsions; D005224:Fats, Unsaturated / Q000737:chemistry*; D005519:Food Preservation; D006801:Humans; D006863:Hydrogen-Ion Concentration; D009812:Odorants / Q000032:analysis*; D010084:Oxidation-Reduction; D010938:Plant Oils / Q000737:chemistry*; D000074242:Sunflower Oil; D014835:Volatilization; D014867:Water / Q000737:chemistry*
D004655:Emulsions; D005224:Fats, Unsaturated; D010938:Plant Oils; D000074242:Sunflower Oil; D014867:Water