Pectic Polysaccharides of Fruits: Characterization, Fractional Changes and Industrial Application - Natural Polymers, Biopolymers, Biomaterials, and Their Composites, Blends, and IPNs - page 224

the ripening phenomenon reflected by solubilization of pectic polymer is not uniform
throughout tissues in a fruit. The reviewer would like to point out at the outset that
researches done by the scientists on pectic compounds in fruits are much extensive and
the studies have covered fruits of a large number of species with particular reference
to those of economic importance. The pertinent works done on majority of such fruits
have been brought in and discussed in the following under the respective headings.
Citruses ( Citrus species) Fruits
Among the edible species belong to the genus Citrus , the mandarin orange ( Citrus
reticulate Blnco.) and the sweet orange ( Citrus sinensis Osbeck) are known to have
supreme importance as table or desert fruits all over the world. In Satsuma mandarin
oranges, the water-soluble pectins in the pulp increased rapidly during advanced ma-
turity condition and decreased gradually in ripening phase (Daito and Sato, 1984).
The acid and water-soluble pectins as well as the total pectin had consistently steeped
up in developing lemon ( Citrus limon Burm.) pulp (Soni and Randhawa, 1969), al-
though a regular increase of pectin content of lemon peel during ripening was also
observed (Ramadan and Domah, 1986). The granulation of juice sometimes appears to
be a great problem in many Citrus fruits. The changes of the different pectic fractions
may be responsible for this granulation (El-zeftawi, 1978). The reduction of NaOH-
soluble fraction of pectin accompanied with an increase in water-soluble pectin was
also observed in process of juice granulation (El-zeftawi, 1978). In order to unfold the
mechanism of hardening of juice-sacs during granulation, the stoichiometric relation-
ship between pectic substances and the level of calcium ions in the healthy, gelated and
granulated juice-sacs from Citrus sulcata fruits were investigated by Goto (1989) and
the amount of calcium ions per unit amount of pectic substances in the EDTA-soluble
fractions had higher in gelated and granulated juice-sacs than in the healthy juice-sacs.
The crystallization of pectic substances as a result of increased levels of calcium ions
in the middle lamella was a cause for hardening of the juice-sacs and collapsed juice
vesicles of grape-fruit (Hwang et al., 1990) and was also associated with a modifica-
tion of water-soluble and chelator-soluble pectin molecular weight.
mango ( Mangifera indica l.)
The pectic compounds and pectic degrading enzymes in mango pulp is a subject of
study, undertaken by some Researchers. The level of pectin along with other constitu-
ents continued to increase in the fruits during their growth as opposed to the reverse
trend for the acidity level in fruits (Gangwar and Tripathi, 1973). The water- and alka-
li-soluble pectic fractions were reported to decrease in contrast to ammonium oxalate-
soluble pectin fraction in ripening stage of mango fruits, irrespective of cultivars vari-
ation (Tandon and kalra, 1984). The polygalacturonase activity markedly increased
during ripening and the loss of fruit firmness is well correlated with this increased
enzyme activity (El-Zoghbi, 1994). The rate of marked changes during fruit ripen-
ing could exert on important influence on storage life and export potentials of mango
fruits. Pectic polymers become less tightly bound in the cell walls during ripening and
this wall loosening phenomenon is involved with hydrolysis of galactose containing