Chemistry Reference
In-Depth Information
Fig. 1.1
The gelation profile of high-ester pectin with 2% GDL at 23
◦
C. Open and closed
symbols indicate replicate experiments. For a colour version of this figure, please see the
colour plate section.
at time zero, forming an initial plateau - parallel to the
x
-axis - before
dropping off as time progresses, and finally showing signs of levelling
off, again parallel to the
x
-axis.
G
will start below
G
with the gap
between them being constant.
G
and
G
then converge and cross, and
finally deviate from each other until there is again a constant gap. The
real results are given in Fig. 1.1.
Immediately apparent is that the predicted results conform to the
actual results obtained, suggesting good agreement between theory -
measurement - and material. Interpretation of the graph allows char-
acterisation of the gelling process: from time 0 to 1800s little or no
structure formation is occurring. The 1800s mark the onset of gelation,
which proceeds until 5500s, where the
G
and
G
profiles cross, the
phase angle value is 45
◦
, and this is termed the gel point. After 5500s,
the gel is building in structure and the graph does not extend far enough
to show the gelled plateau.
In terms of the material and what this means for the customer, one
can reinterpret the graph to say that between 0 and 1800s the wine gum
syrup can here be pumped, moved and deposited into the chocolate
cups or moulds. Between 1800s and 5500s, it is recommended that the
material is not disturbed, so that the gel is allowed to form. Beyond
5500s, the system has set, and a fruit flake, chocolate bead or other
material can be deposited on the surface where it will remain without
sinking into the wine gum.
Questions may now arise from the customer about the time allowed
for filling and depositing, namely 1800s. Could this be altered to op-
timise the process? The gelation process is controlled by the speed at
which the pH is reduced, and therefore governed by the concentration
of GDL. Hence, by varying the GDL concentration, the initial 1800s
plateau can be shortened or extended. This can be monitored simply by
following the pH decrease over time immediately after the addition of
