Celery 331
18.7.1 Toxicity
Celery has been identified as one of the plants known for causing dermatitis due to
phototoxic reactions. Rubatzky and Yamaguchi (1997) have discussed phototoxic
activity in detail in their treatise and have reported that celery foliage and seed
contain phthalides, terpens, psoralen, xanthotoxin, bergapten and isopimpinellin. Out
of these compounds psoralen, xanthotoxin and bergapten are phototoxic causing
dermatitis in humans and animals after contacting the skin in sunlight. Some individuals
exhibit much greater sensitivity to psoralens than others. Normally the concentrations
of these compounds in celery, parsley and other umbellifers does not pose a health
threat for consumption or to field workers handling these plants. The concentration
of these compounds has been found to increase in response to pollutants, cold
temperature, fungal infections, mechanical damage and the ultraviolet spectrum of
sunlight.
Apium graveolens has been listed as the potential photosensitising action crop
(McGuffin et al., 1997) and phototoxic reactions exhibited by the skin are generally
associated with the presence of phenolic compounds such as furocoumarins or psoralens.
Trumble et al., (1990) reported the presence of a much higher concentration of
furocoumarins than petioles. It has been further advised that celery and celery products
should not be used during pregnancy unless otherwise directed by an expert qualified
in the appropriate use of the substance. Therefore, celery preparations carry a warning
against taking celery medicinally in pregnancy or if suffering from kidney disorder
(Chevallier, 2001). The use of celery leaves, stalks and seeds has been condemned
for attempted use as an illegal abortifacient. In one compilation, Sayre (2001) mentioned
that celery seeds lower the potassium levels in the body. If a great deal of celery seed
is consumed, the consumption of bananas and other fresh vegetables containing high
amounts of potassium is needed to counterbalance this effect. Celery seeds have,
therefore been suggested to be toxic if taken in excess. According to Kaufman et al.,
(1999), drowsiness might also be a side effect of celery due to the presence of
phthalides, which have the properties of natural sedatives. Calcium antagonistic
properties of celery due to the presence of coumarins has also been reported. Celery
has been reported to possess calcium antagonistic properties due to the presence of
calcium blocker of phyto-chemical coumarins such as bergapten, at 1–520 ppm,
isopimpinellin, at 4–122 ppm and xanthotoxin, at 6–183 ppm (Kaufman et al., 1999).
In one of the studies Wuthrich et al., (1990) reported that celery is a partly
thermostable allergenic. In addition a relatively high number of cases of severe
anaphylactic reactions due to ingestion of celery have been reported in Switzerland.
It was further added that the thermostable allergenic components of celery allergy
seems to be associated with a co-sensitization of mugwort pollen. In this context
Breiteneder et al., (1995) succeeded in the molecular characterization of celery and
the identification of the Api g 1 gene responsible for allergen of celery.
18.8 Quality specifications.....................................................................
18.8.1 Specifications for whole seeds
The quality of celery seed depends mainly on:
∑ external appearance, which provides visual perception of quality such as colour,
uniformity of size, shape and texture. Celery seeds are minute, globular, light
brown seeds having paler ridges and seeds seldom exceed 1 mm in diameter.