Ikukazu Tashima

Effect of oxidized arachidonic acid and hexanal on the mouse taste perception of bitterness and umami.

The oxidization of fatty acids generates many volatile compounds forming an aroma, but little is known whether mammals use gustatory sense to detect the oxidized products as a taste or only use olfactory sense to detect as an aroma. We examined in this study the effect of aqueous extracts of the compounds from autoxidized arachidonic acid (AA) ethyl ester or hexanal which is the predominant component generated from oxidized AA by the anosmic mouse licking performance to a tastant. The addition of the water extract from oxidized AA or hexanal to a quinine hydrochloride (QHCl) solution decreased the anosmic mice licking frequency at several concentrations of QHCl. Hexanal also reduced the licking frequency of anosmic mice conditioned to avoid MSG at several concentrations of monosodium glutamate (MSG). These results suggest that hexanal would affect mouse taste perception to QHCl and MSG via the gustatory sensation.

Oxidized arachidonic acid and hexanal enhance mouse taste perception of monosodium glutamate

Abstract Objective Little is known about whether mammals use gustatory sense to detect compounds produced from oxidized oil as a taste or only use olfactory sense to detect the compounds as aroma. The present study examined the effects of oxidized arachidonic acid (AA) ethyl ester and hexanal, one predominant compound in oxidized AA, on mouse taste perception of monosodium glutamate (MSG). Method We examined the effects of oxidized ethyl AA and hexanal on chorda tympani (CT) nerve response to MSG using mouse electrophysiological technique. In addition, we evaluated the effects of aliphatic aldehydes and alcohol which are compounds structurally related to hexanal with carbon chain lengths or a functional group different from hexanal on taste perception of MSG using behavioral and electrophysiological studies. Result The CT nerve responses to 10, 20, and 50 mM MSG with water extracts of oxidized ethyl AA was higher than that to MSG alone. A total of 1000 µM hexanal and pentanal enhanced mouse taste response to MSG, but 1000 µM propanal and 1-hexanol failed to increase the responses. Discussion The products of oxidized ethyl AA and hexanal would enhance the taste sensation of MSG, which suggests that CT nerve input should be important for projection to the behavioral responses. The carbon chain length and the functional group of hexanal would be key factors of the hexanal effect on mouse taste perception of MSG.