Excessive bitter taste in citrus juice is a major problem in
citrus industry worldwide because it reduces the quality and
commercial value of the product (Mongkolkul et al.
2006
).
The processing of citrus juice faced formidable problems in
terms of
“
bitterness
”
and
“
delayed bitterness
”
, thereby affect-
ing its consumer acceptability. Bitterness due to flavonoids
and limonoids poses a major problem for the citrus industry.
Without proper de-bittering technology, the profitable citrus
industry cannot flourish (Singh et al.
2003
).
The bitterness in citrus fruit is affected by limonin and
naringin, which are generally recognized as the major two
bitter compounds. Limonin and naringin co-exist in most
citrus cultivars, but in different amounts, and their threshold
levels are different. Premi et al. (
1995
) reported that limonin
and naringinare distributed invarious parts ofthe kinnow fruit
and each part of the fruit contains different amount of limonin
i.e. seeds contained the highest limonin (9.50 mg/g), followed
by peel (4.69 mg/g) and juice (0.128 mg/ml). As many as 37
limonoids have been identified in citrus and their hybrids.
Among them four limonoids namely, limonin, nomilin,
ichangin and nomilic acid are bitter (Maier et al.
1977
). The
cultivar type had an effect on the amount of limonin and
naringin (Pichaiyongvongdee and Haruenkit
2001
).
Limonin is synthesized as a non bitter form of limonoate A
-ring lactone (LARL) in leaves and transported to fruit and
seeds.Hasegawa et al. (
1991
) reportedthat the acidity of citrus
plays a great role in terms of bitterness, because under low pH
conditions, the A-ring lactone (LARL) can be converted to
limonin. When the membrane is ruptured during juice