When confronted with the tiniest forkful of cauliflower or broccoli, some kids can't help but scrunch up their faces in disgust. But don't blame them — a new study hints that specific enzymes in spit might make calciferous vegetables taste particularly vile to some children.
These enzymes, called cysteine lyases, are produced by different kinds of bacteria that live in the mouth. The same enzymes are also locked away in the cells of Brassily vegetables, such as cabbage, Brussels sprouts, broccoli and cauliflower. So when we chomp into a broccoli floret, these enzymes spill out of their storage containers in the veggie's component cells while those in our spit kick into gear.
These enzymes break down a compound called S-methyl-L-cysteine sulfoxide (SMC SO) in calciferous vegetables, and this breakdown process transforms the compound into pungent odor molecules. Previous studies of adults suggest that the level of cysteine lyase activity in a person's spit determines how much the SMC SO breaks down, and therefore, how many stinky molecules get produced in the process. This, in turn, influences how calciferous veggies taste to adults.
According to these past studies, when different adults consume, say, fresh cabbage, there can be up to a tenfold difference in how many sulfurous odors the food lets off as their saliva-borne enzymes break it to bits. But the study authors wondered whether the same variance can be seen in kids, who, compared with adults, are usually more sensitive to bitter and sour tastes anyway. They suspected that kids whose spit produced the most smelly, SMC SO-derived compounds would show the strongest dislike for Brassily vegetables compared with adults and their peers.
And according to the team's new study, published Sept. 22 in the Journal of Agricultural and Food Chemistry, that's just what they found. While both adults' and kids' spit produced smelly compounds when exposed to cauliflower, these odors did not sway whether adults liked or disliked the vegetable. On the other hand, kids whose spit produced high concentrations of these odors reported hating cauliflower the most out of all the study subjects.
In particular, kids seemed sensitive to a stinky compound called dimethyl disulfide (DMTS), an odor that's both a byproduct of SMC SO-breakdown and a scent that gets released by decomposing meat, first author Damian Frank, a food chemistry and sensory food scientist at the University of Sydney, told Live Science in an email.
"DMTS is okay in small doses, but when dominant, it really has a rotten sulfur smell," Frank said. And it turns out, when kids tuck into a serving of cauliflower, some might endure higher quantities of these super-smelly odors than others.
The new study included 98 pairs of parents and children ages 6 to 8. After taking samples of each participant's saliva, the scientists stirred the spit into raw cauliflower powder that they'd concocted in the lab. They measured the SMC SO-derived odor compounds let off by the powdered vegetable, and as in previous studies, they found that each participant's saliva generated a different quantity of stinky, sulfurous scents.
In a separate analysis, the study authors found that broccoli lets off these same noxious smells, but cauliflower actually did so in slightly higher concentrations.
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