Effect of DE of Corn Syrup - staging.files.cms.plus.com

that are cooked for a long time at elevated temperatures would be expected to have the brownest color.
Note that corn syrup has very little protein, but does have small amounts of amine compounds, which
are sufficient to promote Maillard browning. In these experiments, the brown color is indicated by the L
value obtained from the Hunter colorimeter, with lower L values indicating more brown color.
For a given cook temperature, we would expect the L value to decrease as the amount of
reducing sugars increased and cook time increased. When there is variability in replicates it is probably
due to the differences in cook time. Formulations cooked to lower temperature would be expected to
have less color.
Glass transition temperature:
The temperature at which the liquid syrup turns into a solid glassy matrix is the glass transition
temperature (Tg), in this case measured by calorimetry. The two main factors that affect Tg are molecular
weight of the sugars in the syrup and the final water content. In general, the more smaller molecular
weight materials and the higher the water content, the lower Tg. In this experimental data set, both
average molecular weight and water content varied with the formulations and cook process.
One indicator of average molecular weight is the amount of reducing sugars present. In general,
the higher the reducing sugar, the more smaller molecules are present and the lower the average
molecular weight. Thus, we would expect a decrease in Tg with an increase in reducing sugars (lower
average molecular weight).
The second factor that affects Tg is water content. There is a decrease in Tg with increasing water
content.
Moisture sorption:
The hygroscopicity, or propensity to pick up moisture from the environment, of a sugar glass
depends primarily on the composition. It is well known that smaller molecules (like glucose and
fructose) are more hygroscopic than larger molecules, even sucrose and especially the larger glucose
polymers. Thus, we might expect a relationship between moisture sorption and reducing sugar content
of our formulations. Moisture sorption may also be a function of water content since the ability of a glass
to pick up moisture depends on how easily the molecules move around and make room for the water to
penetrate the glassy matrix.
Since Tg depends on both chemical composition and water content in much the same way as
moisture sorption, it is interesting to explore the relationship between sorption and Tg. In a general
sense, formulations that lead to lower Tg, either through addition of lower molecular weight components
or by adding water, result in more rapid moisture sorption.
Other results:
Some of the formulations were made in electric skillets instead of being heated in the copper
kettles over open flame. Does the source of heat have any effect on the results?
One formulation was made with all sucrose. Without the addition of corn syrup or invert sugar,
there was nothing to inhibit the crystallization of sucrose and this formulation was seen to grain by the
time it was poured onto the table. Another formulation was made with all invert sugar, a system that
will not crystallize but will also not form a glass at room temperature. This system was still an
amorphous fluid upon cooling on the table.
Improvement of experiment:
The primary uncontrolled variable in this experiment was the cook time. Some method of
controlling heating to minimize variations in cooking times would be beneficial for reducing the
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