Pectic Polysaccharides of Fruits: Characterization, Fractional Changes and Industrial Application - Natural Polymers, Biopolymers, Biomaterials, and Their Composites, Blends, and IPNs - page 225

polysaccharides (Seymour et al., 1989). However, a close relation between changes in
β-galactosidase activity, tissue softening and increased pectin solubility and degrada-
tion was also observed (Ali et al., 1995).
Guava ( Psidium guajava l.)
Guava is not only a rich source of vitamin C but also stakes its claims to be one of
the top ranking fruits in respect of pectin of high jelly-grade, for which a considerable
part of guava produced is made use of in making fruit jelly in commerce, The amount
of pectin content in fruits was found as maximum in the ripe stage (Pal and Selvaraj,
1979). However, there is a variation of pectin content among the cultivars of the fruit.
A direct relationship on the increase of soluble pectin with an inverse trend between
protopectin and softening in developing fruits has also been observed (El-Buluk et al.,
1995; Esteves et al., 1984). Salmah and Mohamed (1987) observed a sigmoid curve in
regards to the changes of total pectin content during development of fruits while, the
water-soluble pectin followed a linear change (El-Buluk et al., 1995). However, pectin
content is also affected by cropping season and higher amount of polysaccharides
remain persistent with the winter crops (Dhingra et al., 1983). The fractional changes
of pectic polysaccharides in developing fruits revealed that the extent of pectic solu-
bilization was more pronounced in inner pericarp region as compared to outer and
middle pericarp zone of the fruit tissue (Das and Majumder, 2010). A review on pectic
polysaccharides of guava (Marcelin et al., 1990) discussed the metabolism of various
forms of polygalacturonates and pectic degrading enzymes in guava fruits as well as
importance of the levels of these substances for processing industries.
apple ( Mallus pumilla mill)
Plenteous researches have in fact, being done on examining the pectic substances of
apple fruits. Earlier reports (Efimova, 1981; Surinder Kumar et al., 1985; Tischenko,
1973) stated that pectin content decreased during ripening with an increase of poly-
galacturonase activity. Mangas et al. (1992) reported that the alcohol-insoluble solids
decreased with ripening while water-soluble or the chelator-soluble pectin elevated in
the final stage of fruit ripening. However, the galactose and arabinose residues were
lost both from alcohol insoluble residues and different pectic fractions during ripening
of fruits (Fischer and Amado, 1994; Fischer et al., 1994; Redgwell et al., 1997).
Prune Fruits
The rate of fruit softening in peach fruits was negatively correlated with the pectin
associated sugars and the chelator-soluble pectin exhibited a decreasing galacturonic
acid and rhamnose ratio during fruit ripening (Fishman et al., 1993; Maness et al.,
1993; Selli and Sansavani, 1995). In plum fruits ( Prunus domestica L.), the ethanol-
insoluble solids elevated up to a certain level and then fell down and pectin content
parallel; the change in weight of insoluble solids (Boothby, 1983). Batisse et al. (1994)
reported that the oxalate and water-soluble pectic fractions increased while the acid-
soluble part tended to decrease in ripening cherry fruits.