As shown in Fig. 7b, PC1 loadings that included ethanol,
ethyl butanoate, ethyl hexanoate, ethyl butanoate, methyl
hexanoate and diethyl trisulfide were the most significant
variables that also determined the scores of the D2 variety.
The cluster of D24 scores was characterized mainly by
volatile loadings comprising propyl acetate, S-propyl
thioacetate, methyl propyl disulfide, ethyl propyl disulfide
and dipropyl disulfide. PC2 of the variable loading plot
(vertical) related the amount of trithiolanes and disulfides
in the durian aril. Separation of the D101 group from D2
and D24 was attributed to the elevated levels of volatile
methyl 2-methylbutanoate, propyl hexanoate, methyl
octanoate, ethyl 3-methylbutanoate and 1-methylthiopropane.
The D2 variety was perceived as having stronger sweet
and fruity odour from a higher content of aliphatic esters,
while the D24 variety was distinguished by a pungent onion
and garlic sulphur-like odour contributed by alkyl disulfides.
D101 possessed a well-balanced fruity and sulphurlike
aroma with relatively lower level of disulfide and
trisulfide volatiles.