Abstract :
[en] Abstract The impact of polyunsaturated fatty acid (PUFA)
degradation on the survival and acidification activity of
freeze-dried Weissella paramesenteroides LC11 was investigated
over 90-days storage at 4 °C or 20 °C in vacuumsealed
aluminium foil or glass tubes with two water
activities (aw=0.11 or 0.23). Colony counts, acidification
activity (% lactic acid/g), linoleic/palmitic (18:2/16:0) or
linolenic/palmitic (18:3/16:0) ratio by gas chromatography
and 18:2 or 18:3 oxylipins by reversed phase-high performance
liquid chromatography were determined. The
viable cells, acidification activity and 18:2/16:0 or 18:3/
16:0 ratio decreased as the storage time increased. The
survival, acidification activity and 18:2/16:0 or 18:3/16:0
ratio were greatest for the freeze-dried strain held in
vacuum-sealed aluminium foil at 4 °C. The 18:2/16:0 or
18:3/16:0 ratio decrease was correlated with the accumulation
of 18:2 or 18:3 oxylipins during storage in glass tubes.
Hydroperoxy PUFAs, hydroxy PUFAs, divinyl ether
PUFAs and oxo PUFAs were the main oxylipins identified.
A large decrease in the 18:2/16:0 or 18:3/16:0 ratio and a
rapid accumulation of oxylipins during storage might be
enough to cause high cell death and loss of metabolic
activity. These results provide further experimental support
for the hypothesis that lipid oxidation and survival or
activity of freeze-dried bacteria might be related.
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