Chemistry Reference
In-Depth Information
The use of hemicellulases in cracker dough can potentially be also very useful. The
partial breakdown of the water-extractable hemicellulose fraction will lower the water binding
capacity. Hence, more water will be available and softer dough will be achieved. Consequently
less water is needed to prepare the dough. Furthermore, a reduction in baking time will be
achieved, as well as an improvement in quality through more even baking resulting in reduced
checking.
This has also been confirmed by Nabisco,
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who are claiming that the use of a pentosanase
will reduce checking in crackers by reduction of the water content and will be particularly
useful in low fat and/or high-fibre formulations. Dough containing low level of fat or high
level of fibre do require higher amount of water to be added to the process in order to achieve
good machinability. This water also needs to be removed during baking, resulting in longer
baking times. The addition of hemicellulases will result in lower water binding capacity,
hence more water will be available for easier processing.
Also, the addition of (fungal) α-amylase will potentially prevent checking as well as
creating a leavening effect and improved flavour development. The amylase will act on the
damaged starch granules, thereby providing food for yeast to generate carbon dioxide, while
at the same time liberating water from the damaged starch. This will improve the distribution
of water throughout the dough, creating more uniformity, hence less problems with checking
after baking.
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7.6
APPLICATION OF ENZYMES IN WAFERS
Wafer biscuits are made from mainly wheat flour and water to which other minor ingredients
may be added. The manufacturing process consists of preparing a batter, typically 40-50%
flour and other ingredients such as fat/oil, emulsifiers, sugar, egg, salt, sodium bicarbonate
and/or yeast. The batter is usually deposited and cooked between a pair of plates for a short
amount of time at high temperature (e.g. around 2 min at 160
◦
C). The wafer sheets produced
will contain a low moisture level and will be further cooled down and processed according
to requirements of the end product.
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A low batter viscosity and an even dispersion of all
ingredients are essential for uniform wafers with a homogeneous structure.
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The formation
of gluten strands is undesirable as these will block sieves and depositor nozzles.
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Proteases, especially bacterial proteases, can be added to the wafer batter in order to
prevent gluten development and liquefy the gluten, resulting in a uniform mixture with
optimum flow properties. Liquefied protein also binds less water giving the opportunity to
add less water to the batter. Consequently, a lower water level in the batter will result in less
baking time. This effect is strengthened by the addition of endoxylanases able to break down
hemicellulose. The endoxylanase, preferably originating from
Trichoderma sp.
, is able to
hydrolyze the backbone of the arabinoxylan resulting in a moderate release of water due to
the decrease in water binding capacity of the hemicellulose.
Wafer batter test results, shown in Fig. 7.6, clearly indicate that the addition of bacterial
protease originating from
B. amyloliquefaciens
in combination with endoxylanase originating
from
Trichoderma longibrachiatum
immediately lowers the batter viscosity. This indicates
that the water binding capacity has decreased and water has been released. This will allow
the manufacturer to reduce the water proportion by 5-10% (as a function of the flour grade),
which consequently will lead to a reduced energy requirement for evaporation and thus
to a saving of energy. Furthermore, the quality of the wafer also increases by changes in
