Abstract:

A method was developed for the determination of isoorientin, orientin, vitexin, isovitexin and p-coumaric acid
in Indocalamus leaves and rice dumplings wrapped in them by high performance liquid chromatography (HPLC). The
migration patterns of these flavonoid compounds in fresh, vacuum-packaged and quick-frozen rice dumplings during the
cooking process were established by determining their contents in Indocalamus leaves and the wrapped rice. The results
showed that in the first boiling cycle, the migration percentages of flavonoids from indocalamus leaves to rice dumplings
were 7.41%–45.18%. In the second cycle, the contents of flavonoids in indocalamus leaves were rapidly reduced in the
first 30 min by 51.61%–72.48% as compared to the total reduction during the entire period of 120 min, and the migration
percentages of flavonoids were 18.07%–65.94%, which were higher than those in the first boiling cycle. During the storage
period of 30 days, the contents of flavonoids (except for no change in isovitexin) in Indocalamus leaves were reduced in
the first 15 days by 68.60%–85.50% as compared to the total reduction over the whole storage period and the migration
was slowed down from the 15 day onwards; the migration percentages of flavonoids (except that isovitexin did not migrate)
were 25.90%–64.84% during the 30-day storage. During the second boiling cycle and storage period, the migration rates
of isoorientin and orientin were lower than those of other flavonoids. Fresh rice dumplings were most beneficial for the
migration of isovitexin, while quick-frozen samples were beneficial for the migration of other flavonoids. The migration of
isovitexin under vacuum and quick-frozen conditions did not happen in a short time.

Key words: rice dumplings, Indocalamus leaves, flavonoids, high performance liquid chromatography (HPLC), migration pattern