THESIS

1.3.3 Degree of syneresis
115
The effects of enzyme concentration on the degree of syneresis of
debranching and freeze-thaw cycle (-10/30°C) of 15 % rice starch paste preheated at
121°C for 30 min showed in Figure 27. The concentration of pullulanase enzyme was
fixed at 0, 8, 10, 12, 14 and 16 unit/g starch were debranched in a water bath at 55°C
for 16 hr. The degree of syneresis for the freeze-thawed cycle of debranched rice
starch paste in the range of 8 to 16 unit/g starch of pullulanase concentration were
higher (53–58 %) than the non debranched freeze-thawed cycle of rice starch paste
(34 %). Moreover, the degree of syneresis was not significant difference between rice
starches gels treated with 12 to 16 unit/g pullulanase concentrations. The debranched
rice starch gel was dramatically lost expressible water in the 8 to 10 unit/g starch
hydrolysis and remained relatively constant thereafter indicating a very high
concentration of pullulanase treatments. In general, the rate of water syneresis of
starch paste after freeze-thaw treatments correlated well with prolonged refrigeration
tests and with quality evaluation of frozen starch-thickened foods. In addition, the
technique was developed for cold-resistant starches, it has been used on a wide range
of starches (Wu and Seib, 1990 and Kim et al. 2006).
Degree of syn eresis ( %)
60
50
40
30
20
10
0
0 8 10 12 14 16
Enzyme concentration (unit/g starch)
Figure 27 Effect of pullulanase enzyme concentration (0 to 16 unit/g starch for 16h)
on degree of syneresis of 15 % HARS preheated at 121°C for 30 min