Food Biochemistry and Food Processing

12 Pectic Enzymes in Tomatoes 281

pastes of the different genotypes indicates that sup-
pression of PG or Exp1 results in small increases in
the number of particles below a diameter of 250 m
(Fig. 12.5). Suppression of Exp1 also results in the
appearance of some larger particles, above 1400 m
in diameter. The presence of these larger fragments
shows that suppression of Exp1 affects the way the
cells and cell walls rupture during processing. Bio-
chemical characterization of cell-wall polymers did
not show large differences in the amounts of ex-

tractable polyuronide or neutral sugar in sequential

cell-wall extracts of juices and diluted concentrates

of the various genotypes. Only minor size differ-

ences appear in individual polymer sizes in sequen-

tial extracts. In suppressed PG genotypes, larger

pectin sizes were observed in the CDTA extract. The

most dramatic difference was in the carbonate ex-

tracts, where the double suppressed line contained

larger pectin polymers at all concentration levels rela-

tive to other genotypes (Kalamaki 2003). Concurrent

Figure 12.5.Particle size determination in juice and paste from control and suppressed PG/Exp1 fruit. (Redrawn
from Kalamaki et al. 2003a.)