Bitterness is a major problem in the citrus in-
dustry worldwide, and is mostly due to the presence of
limonoid compounds, especially limonin. In this study,
the limonin content of orange juice concentrates from
three active factories in west Mazandaran province, after
reconstitution, was assayed using high-performance liquid
chromatography (HPLC) and spectrophotometric meth-
ods. With HPLC, employing acetonitrile/water (v/v)
(32:68) with a flow rate of 0.9 ml/min at
l
=207 nm, the
limonin content was in the range 11.7–23.3
m
g/ml with a
mean € standard deviation (SD) of 18.5€3.6
m
g/ml.
Spectrophotometric measurement of limonin at 503 nm
with Burnham reagent gave a range of 9.9–21.8
m
g/ml
with a mean € SD of 17.16€4.1
m
g/ml. The correlation
coefficients of the detector linear response for the limonin
standard (0–50
m
g/ml) for HPLC and spectrophotometry
were 0.995 and 0.989, respectively. The percentages of
limonin recovery with and without sample addition were
101.02–111.40 and 93.0–100.8, respectively, for HPLC.
The percentages of limonin recovery for the spectropho-
tometric method resulted in 95.6–101.8 for limonin-added
samples. The precision factors for the two assay methods
were €2.10% and €1.69, respectively. The correlation
coefficient of the two methods was 0.84. Sensory evalu-
ation of the reconstituted samples from the view point of
bitterness confirmed 85% of the results of the analytical
methods. This study recommends spectrophotometric
analysis as a useful and suitable method for quantitation
of limonin in the quality control laboratories of orange
juice plants