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Ponkan (Citrus reticulata Blanco, var.Ponkan ) fruits stored at
10℃, 15℃, 20 ℃, and room temperature (20± 2℃ ) for seven
weeks, the major bitter compound,limonin, in the extracted
juices all decreased from 15.6mg/Kg to 2±1mg/Kg(approximately
87% redu- ction ), and remain at this level through the 13th
week. Another major bitter compound in Ponkan juices,
nomilin, are also shown the reduction from 3.2mg/Kg to
undetectable level in eight weeks. Except for the fruits stored
at10℃, the limonin contents of the fruits stored at 15℃,
20℃, and room temperature were decreased from 15.6mg/Kg to
8.7mg/Kg, 8.0mg/Kg, 5.0 mg/Kg,which are 44.6%, 45.2%,and67.8%
reduction,respectively. Titratable acids, soluble solids andL-
ascorbic acid were de- creased during fruitstorage. Rapid
reduction of titratable acids resulted in increase of sugar/
acid ratio. Thesugar/acid ratio of fruits stored at 10℃
forexample, increased from 19.8 to 45.7 in 13 weeks.Considering
the total quality of Ponkan juice, the sugg- ested fruit
storage condition are room temperature for no more than two
weeks. Addition of 2g Amberlite XAD-4 and XAD-16resins to 100g
Pon- kan juices and stirred for 60 min, limonin reduction
were 64.8% and 86.6%,respectively. XAD-16 resins showed
better debittering capacity than XAD-4. Similar resultswere
also found in nomilin content. Comparison of Amberlite XAD-7
and XAD-16 resins for their continuously Ponkan juice
debittering capacity, one unit weight of XAD-7 resins were
able to debittering 1350times weight of the Ponkan juice,
which is superior than the 240 times capacity when using XAD-16
resins. Cleaning of used resins using 95% ethanol
demonstrated better resin regeneration than 2%NaOH solution.
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