is done with (0.1 % HCl) and then the analyte was subjected to polarimetry, and the specific angle of rotation
was also recorded.
3.1 Quantification of acrylamide
Working standard solutions for the standard curve as
well as the sample recovered in hexane were analyzed
using the GC-FID chromatographic system.
4 DISCUSSION
A study of the levels of precursors responsible for
the formation acrylamide (AA) in roasted maize at
high temperature is reported. Although the amounts
of acrylamide in the roasted maize samples were not
quantified, the glucose–fructose ratios explain sufficiently the overall trend of acrylamide content in the
samples. It was observed that the moisture content
of raw maize was higher when compared to that of
roasted maize, indicating a loss of water when samples were roasted at elevated temperature. However,
the loss of moisture content after roasting was not significantly high. This implies that the moisture content
in roasted maize is still high enough to suppress the
formation of acrylamide, which accounts for the low
limit of quantification (LOQ) factor observed in this
study. This finding is in agreement with observations
made by Elmore and Zhang that formation of acrylamide is related to moisture content and it only forms
when it falls below 5% for some foods (Elmore et
al. 2005; Zhang et al. 2009). The specific angle of
rotation recorded from water-based extracts obtained
when raw and roasted maize samples were extracted
with water proved to be levorotatory, as shown in
Figure 3.
Figure 3. Angle of rotation of water-based extracts
obtained from raw maize samples.
The angle of rotation for sucrose in maize or any
other starchy food is expected to be dextrorotatory, but
observations indicating the angle of rotation to be levorotatory in nature is due to the presence of a mixture
of glucose and fructose in a sample. Indeed levorotatory fructose has a greater molar rotation than the
dextrorotatory glucose (Panpae et al. 2008).
From our study, and as shown in Figure 4, it
is clear that the angles of rotation measured from
water-based extracts obtained from roasted maize samples were lower than those observed in raw maize
samples—an indication of decreased amounts of fructose in roasted maize, probably due to the Maillard
reaction.
Figure 4. Angle of rotation of water-based extracts
obtained from roasted maize samples.
Acid hydrolysis of the sample extracts resulted in a
decrease in sucrose content due to its inversion to glucose with subsequent formation of a glucose–fructose
mixture. It may be concluded that the more the glucose is formed through inversion process, the more
dextrorotatory behavior the extract exhibits, as shown
in Figure 5.
Figure 5. Angle of rotation of raw maize acid hydrolyzed
extracts.
The angle of rotation of roasted maize is reduced
when maize is roasted suggesting the depletion of glucose occurs when raw maize is roasted, as observed in
Figure 6.
71
was also recorded.
3.1 Quantification of acrylamide
Working standard solutions for the standard curve as
well as the sample recovered in hexane were analyzed
using the GC-FID chromatographic system.
4 DISCUSSION
A study of the levels of precursors responsible for
the formation acrylamide (AA) in roasted maize at
high temperature is reported. Although the amounts
of acrylamide in the roasted maize samples were not
quantified, the glucose–fructose ratios explain sufficiently the overall trend of acrylamide content in the
samples. It was observed that the moisture content
of raw maize was higher when compared to that of
roasted maize, indicating a loss of water when samples were roasted at elevated temperature. However,
the loss of moisture content after roasting was not significantly high. This implies that the moisture content
in roasted maize is still high enough to suppress the
formation of acrylamide, which accounts for the low
limit of quantification (LOQ) factor observed in this
study. This finding is in agreement with observations
made by Elmore and Zhang that formation of acrylamide is related to moisture content and it only forms
when it falls below 5% for some foods (Elmore et
al. 2005; Zhang et al. 2009). The specific angle of
rotation recorded from water-based extracts obtained
when raw and roasted maize samples were extracted
with water proved to be levorotatory, as shown in
Figure 3.
Figure 3. Angle of rotation of water-based extracts
obtained from raw maize samples.
The angle of rotation for sucrose in maize or any
other starchy food is expected to be dextrorotatory, but
observations indicating the angle of rotation to be levorotatory in nature is due to the presence of a mixture
of glucose and fructose in a sample. Indeed levorotatory fructose has a greater molar rotation than the
dextrorotatory glucose (Panpae et al. 2008).
From our study, and as shown in Figure 4, it
is clear that the angles of rotation measured from
water-based extracts obtained from roasted maize samples were lower than those observed in raw maize
samples—an indication of decreased amounts of fructose in roasted maize, probably due to the Maillard
reaction.
Figure 4. Angle of rotation of water-based extracts
obtained from roasted maize samples.
Acid hydrolysis of the sample extracts resulted in a
decrease in sucrose content due to its inversion to glucose with subsequent formation of a glucose–fructose
mixture. It may be concluded that the more the glucose is formed through inversion process, the more
dextrorotatory behavior the extract exhibits, as shown
in Figure 5.
Figure 5. Angle of rotation of raw maize acid hydrolyzed
extracts.
The angle of rotation of roasted maize is reduced
when maize is roasted suggesting the depletion of glucose occurs when raw maize is roasted, as observed in
Figure 6.
71