Jackfruit flesh has a distinct fruity aroma, which is known for increasing in intensity as the fruit ripens. The ripe and unripe fruits are eaten very differently: unripe jackfruit is often eaten as a vegan substitute for pulled pork, while ripe jackfruit can be used as an ingredient in many different desserts! In fact, in the West, unripe jackfruit is much more popular, as many Caucasians do not like the aroma of ripe jackfruit. Thus, we set about to analyze a ripe jackfruit to identify the compounds that divide opinions.
Ripe jackfruit
In a fresh jackfruit sample, 35 unique compounds were found, 24 of which were ester structures. Esters formed over 80% of the abundance of compounds in the jackfruit, and were all formed from various combinations of the 3 alcohol structures we identified: 1-Butanol, and its 2-methyl and 3-methyl variants. Among these compounds we discovered, 2 esters were present in the highest amounts: butyl acetate and butyl isovalerate, together comprising 35% abundance of the sample. Both these compounds are present in such high amounts as to be instantly detectable by smell. It is thus likely that these compounds are the source of the jackfruit aroma.
Left to right: 1-butanol, butyl acetate and butyl isovalerate
Esters are a class of organic compounds with aromatic properties, and as such are highly useful in the food flavoring industry. These compounds are either extracted from fruits such as jackfruit and apple or artificially synthesized, and used to add flavor to foods such as candy and ice cream, among others. Butyl acetate is a widely produced food flavoring that also occurs naturally in bananas and apples, while butyl isovalerate is said to have more of a pineapple or peach smell. Both of these esters contribute to the unique jackfruit aroma.
The fresh jackfruit flesh was analysed by headspace Gas Chromatography-Mass Spectrometry (GC-MS), followed by ChemoPower’s SmartDalton and MoleculeDB technology. This allowed us to finish analysis and data processing within one day, which would be impossible using conventional analysis methods. We were able to separate the different compounds quickly and accurately.
Analyzing samples through ChemoPower’s MoleculeDB software
We plan to analyze an unripe, odorless jackfruit, and observe if these noted compounds are still present in the same quantities. If they are not, that will confirm that these esters are the source of the aroma we can currently observe.
It is also worth noting that different varieties of jackfruit have slightly different aromas. Analyzing different strains of jackfruit could also help us isolate which compounds cause jackfruit to smell the way it does!
Written by Edmund Ho, Intern (National University of Singapore)