Effect of oxygen and free fatty acids on cucumber flavour generation

Abstract

A real time monitoring of key flavour volatile compounds released during the cucumber tissue disruption was measured by Atmospheric Pressure Chemical Ionisation-Mass Spectrometry (APCI-MS). The rapid generation of C-6 and C-9 aldehydes in cucumber was prevented by macerating under nitrogen atmosphere. Replacement of nitrogen with air resulted in production all volatiles, but the amount was about one half of the control. The addition of linolenic acid (C18:3) in cucumber tissues resulted in a large increase in nonadienal and hexenal, while addition of linoleic acid (C18:2) significantly increased the levels of nonenal and hexanal. Addition of both linolenic and linoleic acid increased the formation of both nonadienal and nonenal, but the amount was less than that noted when fatty acids were added individually. These results confirmed that the precusors of nonadienal and nonenal in cucumber were linolenic and linoleic acids, respectively, which were enzymatically produced during maceration of cucumber tissue in the presence of oxygen via lipid oxidation pathway.