Introduction:
Despite being healthy and nutritious, Brassica vegetables like broccoli, cauliflower, etc. are not much liked by many of the children and a few of the adults. Some people believe that this is because the taste of these vegetables doesn’t satisfy the ideal criteria of being sweet or salty which children prefer to eat willingly, instead they have a bitter flavor which most of the children tend to refrain from. But is this the actual logic behind this fact? Let’s have a look at it through the eyes of chemistry.
Recent research conducted by Damian Frank and his colleagues at CSIRO, Australia’s National Science Agency provides an appropriate answer to this. In their research article titled ‘In-Mouth Volatile Production from Brassica Vegetables (Cauliflower) king in an Adult/Child Cohort’, they intended to scrutinize the differences in volatile production of sulfur in saliva from children and adults and then study how this affects the acceptance of Brassica in them.
Research:
Brassica vegetables are health-giving owing to the presence of Glucosinolate (GLS) compounds but their breakdown products i.e., Isothiocyanates (ITCs) are responsible for its unpleasant bitter taste and pungent smell.
S-methyl-L-cysteine sulfoxide (SMCSO) is an amino acid-like sulfur storage compound found in Brassica vegetables. The enzyme cysteine sulfoxide lyase breaks down SMCSO and results in the formation of pungent odor-active sulfur volatile compounds, dimethyl disulfide and dimethyl trisulfide. The researchers used an ex vivo Proton Transfer Reaction Mass Spectrometry (PTR-MS) to identify and examine these compounds present in raw and steamed cauliflower powder.
A cohort of child-adult pairs was asked to rate these key odor compounds and dimethyl trisulfide was found to be the least liked odor. Later, the fresh saliva samples of all the individuals were incubated with the raw cauliflower powder and the differences in sulfur volatile production were analyzed.
Large differences in the rate of in-mouth sulfur volatile production were measured between individuals. The similarity in the levels of sulfur volatile production was observed in the children and their parents, which is mostly because of the similar composition of saliva and shared oral microbiomes. On the contrary, dissimilarity was observed in the amount of sulfur volatile production and disliking of the raw cauliflower in the parent-child pairs. Children with high production of sulfur volatiles disliked Brassica vegetables but in adults, this correlation was missing. The reason behind this was that with time the adults learn to tolerate the bitterness of Brassica vegetables and thus they don’t dislike it as much as the children do.
Results:
So, it was concluded that the levels of sulfur volatile production in saliva affects the in-mouth flavor and perception of Brassica vegetables and the individuals with high levels of these compounds would have lower acceptance of Brassica vegetables but this relationship would be stronger in children as compared to adults because of the increased tolerance to bitterness in adults.
Reference:
In-Mouth Volatile Production from Brassica Vegetables (Cauliflower) and Associations with Liking in an Adult/Child Cohort, Journal of Agricultural and Food Chemistry (2021).
Blog by: Aditi Singh
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