Abstract:

In this study, sodium carbonate solution and sodium sulfite solution were used as wax removers to smear the
surface of wolfberry (Lycium barbarum L.) fruits and the fruits without wax removal were used as blank control. The
changes in phenylalanine ammonialyase (PAL) activity and total flavonoid content were determined during sun-drying
of wolfberries. Variations in kaempferol, rutin and quercetin contents were also analyzed by high performance liquid
chromatography (HPLC). Meanwhile, correlation analyses were conducted between the content of total flavonoids and PAL
activity, and among the contents of kaempferol, rutin and quercetin. The results showed that continuous accumulations
of PAL activity and total flavonoids were determined during sun-drying. The contents of kaempferol, rutin and quercetin
increased firstly and then decreased. Using the same wax remover, the content of total flavonoids exhibited a significantly
positive correlation with PAL activity. There were also positive correlations among the variations in the contents of
kaempferol, rutin and quercetin for the same treatment. Wax removers affected PAL activity and the contents of total
flavonoid, kaempferol, rutin and quercetin at the same drying time. The time to reach the highest values of total flavonoids,
kaempferol, rutin and quercetin was also influenced by wax removers.

Key words: Lycium barbarum L., flavonoid, phenylalanine ammonialyase, sun-drying, kaempferol, rutin, quercetin