Why Do Children Dislike Cauliflower and Broccoli? Chromatography Explores

Getting kids to eat their greens is a challenge faced by most parents. Some of the most difficult contenders are broccoli, cauliflower, cabbage and Brussels sprouts – all part of the Brassica family.

That’s not the only thing they have in common. Even children and adults who like these vegetables will have noticed the unpleasant, sulphurous smell that comes from them when cooking or even eating.

So why is it that some people dislike them and others don’t? And is it really the case that children find them more intolerable than adults?

Investigating the microbiome

The odour produced by Brassica vegetables is down to the compound S-methyl-ÊŸ-cysteine sulfoxide. It produces odours as a reaction to an enzyme in the plant’s tissues. However, the same enzyme has been identified in the oral microbiome of some adults.

Put simply, some people will experience a stronger odour from Brassica vegetables, depending on the levels of S-methyl-ÊŸ-cysteine sulfoxide in their oral microbiome. To find out more about this phenomenon, researchers at the Commonwealth Scientific and Industry Research Organisation (CSIRO) investigated how those levels differed in both adults and children.

Rate this smell…

Using gas chromatography-olfactometry-mass spectrometry, they identified the main odour-active compounds in cauliflower and broccoli (both raw and steamed). The use of chromatography to identify compounds in food samples is discussed in the article, ‘A question of taste?’.

They then asked 98 children aged 6-8 to rate those key odour compounds. Each child was paired with their parent, who was also asked to rate the compounds. The worst-rated odour by both children and adults was dimethyl trisulfide, found broccoli and cabbage as well as onion and leek.

In doing so, they pinpointed one of the main compounds responsible for the smell and taste that puts both adults and children off Brassica vegetables.

So why do some people like it?

To see how the results varied from person to person, researchers then mixed raw cauliflower powder with saliva samples to see how volatile compounds developed. There were large differences in production of the sulphur volatile between individuals. Interestingly, children typically had similar levels to their parents, indicating a similar or even shared microbiome.

Children with saliva producing the highest amounts of sulphur volatiles were also those who disliked raw Brassica vegetables the most. In contrast, there was no such relationship for adults. This may simply be down to them tolerating the initially unfamiliar flavour over time.

One conclusion from the research is that children who dislike Brassica vegetables are likely to have parents who also disliked it – albeit when they were children themselves. At the very least it shows that the battle to get kids eating their greens is not in vain, with adults more tolerant to Brassica vegetables despite retaining the microbiome that produces sulphur volatiles.