Jp. Roozen et al., ENZYMATIC AND AUTOXIDATION OF LIPIDS IN LOW-FAT FOODS - MODEL OF LINOLEIC-ACID IN EMULSIFIED HEXADECANE, Food chemistry, 50(1), 1994, pp. 33-38
The oxidation of linoleic acid in emulsified hexadecane, which is iner
t to oxidation, was examined as a model for low fat foods. Static head
space gas chromatography was used to investigate the release of small
amounts of volatile compounds in emulsion systems. At room temperature
the initial rate of oxidation by lipoxygenase decreased in the presen
ce of emulsion droplets. However, the total amounts of intermediate hy
droperoxides formed after 4 h were similar, as well as the amounts of
decomposition product hexanal formed after 22 h at 40 degrees C. There
was no effect of droplet size of the emulsions tested. Increase of em
ulsion concentration from 0 to 2.4% gradually reduced the amount of he
xanal released from the emulsions. The enzyme preparation used acceler
ated the formation of hexanal from methyl linoleate hydroperoxides pre
pared by autoxidation. However, hexanal was more readily formed from t
he linoleate hydroperoxide produced by the lipoxygenase preparation. A
utoxidative decomposition of methyl linoleate at 40 degrees C produced
about the same amounts of hexanal as the corresponding linoleate cont
aining model systems at 60 degrees C. This study showed that lowering
the fat contents of foods may increase the chances of flavour defects.