Certain bacteria present in the mouth mix with certain enzymes in green vegetables, producing an unpleasant, sulfurous odor.
- Brassica vegetables contain S-methyl-ʟ-cysteine sulfoxide which produces a potent odor when interacting with the same enzyme from bacteria found in the oral microbiome.
- Parents and their children usually have a very similar bacterial population in their saliva.
For some parents, getting their kids to eat greens – like broccoli and brussels sprouts – is impossible. A new study reveals that far from being a whim, the disgust for these foods would result from the presence of certain bacteria in the mouth which would cause an unpleasant and sulphurous smell. These results were presented on September 22 in the Journal of Agricultural and Food Chemistry.
oral microbiome
Some oral bacteria can mix with certain enzymes in these vegetables, producing an unpleasant, sulfurous odor. Specifically, it is Brassica vegetables, such as cabbage, bok choy, turnips, broccoli, mustard, and many others, that contain a compound called S-methyl-ʟ-cysteine sulfoxide. This produces a potent odor when it interacts with the same enzyme from bacteria found in the oral microbiome.
Ironically, the study reveals that parents should blame their own microbiome if their children don’t like to eat broccoli. Previous studies show that levels of odor-producing S-methyl-ʟ-cysteine sulfoxide vary among adults. However, parents and their children usually have a very similar bacterial population in their saliva.
The rotten, the sulfur and the putrid
For this study, Australian researchers observed how adults and their children react to Brassica vegetables depending on the composition of their microbiome. They discovered that children having high levels of these volatile compounds in their saliva led to them hating these vegetables. They used a process called gas chromatography-olfactometry-mass spectrometry to identify key odor compounds in raw and steamed cauliflower and broccoli.
From this, 98 child-parent pairs rated the smells coming from these green vegetables. Each of the children was between six and eight years old. Dimethyl trisulfide ranked as the most unpopular smell from raw broccoli and cauliflower among children and their parents. The study authors say that this compound smells “the rotten, the sulfur and the putrid”.
Learning to Tolerate the Flavor of Brassica Vegetables
To chemically assess the differences in feeling between the participants, the researchers mixed saliva samples from the volunteers with raw cauliflower powder. The team discovered large differences in the production of volatile sulfur compounds between the participants. On the other hand, the results were very similar between the parents and their children.
Surprisingly, parents of children with high levels of volatile compounds in their saliva did not dislike broccoli and cauliflower as much as their youngsters. “That’s probably because the adults in the study learned to tolerate the flavor of Brassica vegetables over time.”, suppose the researchers.
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