Amylose and amylopectin were isolated following the method of
Song and Jane (2000) with slight modifications. The starch slurry
(13.3 g/L) was heated and stirred in a water bath at 96
C for 1 h. The
starch solution was filtered to remove insoluble residues, adjusted
to pH 6.3 with phosphate buffer, autoclaved at 121
C for 1 h, and
then boiled and stirred at 96
C for 2 h to disperse the starch
molecules. One fifth volume of n-butyl alcohol was then added to
the starch solution. The solution was cooled to room temperature
over a period of 24e36 h. The amyloseebutyl alcohol complex
crystals that formed and precipitated during cooling were separated
by centrifugation (8700 g, 30 min). The solution was treated
twice more with n-butyl alcohol to obtain residual amylose. The
amylopectin remaining in the supernatant was obtained by precipitation
with at least two volumes of ethanol, followed by
centrifugation. The amylose content of the native starch of jackfruit
seed was measured colorimetrically using Juliano's method
(Juliano, 1971) based on amyloseeiodine complex formation, as
described by Tran, Lee, and Park (2013).