If your child refuses to eat broccoli, it’s because they have invisible bacteria in their mouth. Scientists have found that some vegetables such as broccoli, cauliflower, cabbage, and Brussels sprouts taste much worse for some children than they do for adults because children and adults have different levels of oral microbes. In a study published on Wednesday in the Journal of Agricultural and Food Chemistry, researchers found that saliva and enzymes from these vegetables can produce an unpleasant, sulfurous odor in the mouth. The compounds found in vegetables taste worse for some children than for their parents. This is why some children dislike them more than their peers because of the compounds present in vegetables.
Plants in the mustard and cabbage family include the brassica vegetables that contain the compound S-methyl-L-cysteine sulfoxide. As a result of the reaction with an enzyme within the plant’s tissues, sulfurous odors are produced. Bacteria in people’s mouths also produce the same enzyme. In the study, researchers at the Commonwealth Scientific and Industrial Research Organisation (CSIRO), Australia’s national science agency, sought to find out if children and adults produced different amounts of sulfur odor in their saliva. Their goal was to determine whether mouth bacteria affect the preference for Brassica vegetables.
The researchers investigated the odorous compounds present in raw and steamed cauliflower and broccoli using gas chromatography-olfactometry-mass spectrometry. The method involves separating chemical mixtures into their constituent gases and identifying them. After that, 98 child-parent pairs between the ages of 6 and 8 were asked to rate key compounds based on their odor. Children and adults dislike the smell of dimethyl trisulfide, which smells like rotten. As part of the study, saliva samples were mixed with raw cauliflower powder and odorous compounds were analyzed over time.
Sulphur odor production varied widely among individuals. Raw brassica vegetables were disliked most by children whose saliva contained high levels of sulfur compounds. Adults, however, did not experience the same results. Even people with high levels of sulphur odour production in their mouths may eventually learn to tolerate the taste. These results provide a new explanation for why some children dislike certain vegetables so strongly.