Chemistry Reference
In-Depth Information
Wheat
Waxy maize
HPMC
Modified waxy maize
8.0
6.0
4.0
2.0
0.0
0
50
100
150
200
Amylase activity (U per mL)
Fig. 8.6
Effect of amylase activity on potassium concentration in the aqueous phase after
mixing of the four different viscous systems (480 mPa
s at 50 per second). Reproduced
from Ferry et al. (2006b), copyright 2006, with permission from the American Chemical
Society.
ยท
A sensory study was carried out on soups thickened with these four
systems using panellists whose in-mouth amylase activity had been
measured. The correlation coefficients between the panellists' amylase
activity and saltiness score are shown in Table 8.1.
It is noteworthy that for the starch suspensions that have an initial
microstructure consisting predominantly of swollen granules (wheat,
modified waxy maize), there is a highly significant negative correlation
between amylase activity and perceived saltiness. When this is consid-
ered in conjunction with
the initial drop in K
+
detected at the liquid surface after mixing
when amylase is added to the starches that have a granular micro-
structure, i.e. modified waxy maize and wheat,
the poorer salt release from and mixing ability of the HPMC and
native waxy maize starch-thickened systems,
this supports the hypothesis that, at high viscosities, a particulate micro-
structure is better than a polymeric one to impart enhanced salt percep-
tion. In the absence of amylase, the difference between 'solutions' of
native waxy maize starch with its poor granular integrity and 'solutions'
of wheat and modified waxy maize starch which have a more particulate
microstructure is clear.
