Abstract:

Naringin and limonin are the major compounds responsible for the bitter taste of citrus juice. Although naringin
could be effectively transformed to a nonbitter chemical by naringinase, limonin is hard to be removed from citrus juice.
Naringenin is the hydrolysis product of naringin, and always disturb the determination of limonin in case of HPLC analysis
due to similar polarity and overlapped absorbance spectra with naringin. In order to develop the juice processing and
debittering process on the basis of naringinase treatment, a high performance liquid chromatography (HPLC) procedure was
established and used to study the effects of naringinase treatment, condensation and low-temperature storage on limonin in
pummelo juice. The results showed that the HPLC method achieved complete separation of limonin from naringin, prunin
and naringenin, which protected correct determination of limonin by removing the disturbance from naringenin. The limit of
detection, limit of quantification, recoveries and relative standard deviations (RSDs) were 0.95, 3.17 μg/mL, 102.6%–104.2%
and 0.34%–1.04% for limonin, respectively. Moreover, heat treatment, concentration and storage at low temperatures could
promote crystallization and make it easy to eliminate limonin from pummelo juice. By using a combined process consisting
of naringinase treatment, condensation, storage at low temperature and centrifugation of limonin crystal, 78% of the limonin
was removed from the juice, thus resulting in a pummelo juice containing 19 μg/mL of limonin.

Key words: high performance liquid chromatography (HPLC), pummelo, juice, limonin, naringinase