Rice Noodles: Materials, Processing and Quality Evaluation
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3.1 Mixing
Mixing is the initial process in the formation of
noodles. Water is added to flour in a container and
other ingredients are also mixed. The ration of
flour to water must be appropriate in order to make
dough of optimum consistency. Mixing resulted in
a uniform distribution of ingredients and also even
hydration of flour. In the noodle making industry,
two types of mixers are mostly used: the vertical
mixer and the horizontal mixer. Generally, the
mixers work at a speed of 70 to 100 rpm for 10-
20 minutes and provide proper mixing and some
kneading actions. However, vertical mixer is
usually used on a large scale continuous product
of noodles. The blades of vertical mixers have
a large surface area that aid in the distribution of
water evenly throughout the flour during the initial
stage of mixing. It also provides a certain extent
of kneading action after sufficient hydration of
the flour. On the other hand, the horizontal mixer
has single shaft or double shafts. The double shaft
horizontal type mixer has shown best result in the
mixing of dough. The blades of the shaft move in
opposite direction, so that the dough crumbs move
both horizontally and vertically during mixing [1].
Different types of mixers are also developed in
the industry for performing noodle mixing i.e. low
speed super mixer, continuous high speed mixer
and the vacuum mixer. Low speed super mixer is
used to mix dough with higher water absorption
capacity. It is considered a copy of hand mixer and
performs mixing at a speed of less than 10 rpm to
minimize damage to the starch and protein matrix
[1]. While the continuous high speed mixer is used
to mix water and flour evenly in a very quick time.
Water is added to the flour, which is rotated at a
speed of 1500 rpm. High speed mixing leads to
the formation of greater surface area for maximum
hydration of water. Nowadays, vacuum mixer is
used extensively in noodle industry. The vacuum
mixing let addition of extra water to the flour
without effecting processing efficiency [1, 5, 50].
The process of mixing is affected by flour quality,
the addition of certain components, the volume
of water added, the humidity and temperature of
the processing environment. The water hydration
correlates positively with protein concentration and
can form dough crumbs of large size, consequently
need less time for mixing [5, 34]. The greater
level of damaged starch granules resulted from the
milling of flour can also contribute to the increased
water absorption capacity [50]. The concentration
of water should be optimized in order to develop
dough with good processing characteristics [5]. The
ingredients such as salt and alkaline salt can also
help flour hydration during mixing. Mixing process
conducted at lower temperature slow down the
hydration of flour. It is also not desirable to perform
mixing process at a temperature of greater than
35
o
C, as enzymatic activity and protein degradation
can occur at such higher temperature. The optimum
temperature is for making proper noodle dough is
25-30
o
C [50]. Afterward, the dough is rested for
some time that allows uniform hydration of flour
particles and allows distribution of water to the
dough mixture. The crumbly dough is agitated at
a speed of 5-8 rpm for 10 to 20 minutes during the
resting stage that avoid development of large dough
crumbs and also facilitate dough feeding during the
sheeting process [1, 5, 34, 50].
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