Cereals processing technology

144 Cereals processing technology
shift in dough pH to 9–11.5. At this pH the endogenous and normally colorless
flavanoid compounds undergo a chromophoric shift and display a yellow color.
There is considerable diversity in the various types of alkaline noodles
throughout Asia. It is believed that they originated in the southern provinces of
China, Guandgdong, Fujian and Guangxi. 32 In terms of popularity the fresh
‘Cantonese’ and the partially cooked ‘wet’ Hokkien are the preferred noodle
types. Instant noodles, although a subset of this type, have become so popular
that they are discussed elsewhere in this text.
7.4.1 Flour requirements
In Japan the Chinese or Cantonese style noodles are associated with very high
quality mill streams, 0.32–0.40 percent 5,21 ash content and display excellent
color derived from hard wheat used in bread production. In many other countries
the demands on ash content is not as stringent and allowable levels of 0.50–0.55
percent are not uncommon. Bran contamination is extremely critical as the raw
noodle must have good color stability over a 24 h period. It is not uncommon for
flour color grade to take precedence over a specific ash content in the selection
process for some firms. Microscopic investigations of raw noodles have shown
that undesirable discoloration is associated with non-endosperm material. Autooxidation
of the endogenous phenolics in an alkaline environment can cause
severe discoloration of the product over time.
In Japan flour protein content ranges from 10.5–12 percent while in other
countries a maximum of 13.5 percent is common. The addition of alkali reagents
toughens the dough, reducing farinograph development time and dough
extensibility while increasing extensograph maximum resistance. Optimum
flour protein for the popular Hokkien noodle is approximately 10.5 percent.
Sensory evaluations of alkaline noodles indicate that a flour protein level
below 10 percent yields a poor eating quality noodle. Strong correlations
between the nature of the protein, as determined using the SDS sedimentation
test, rather than simply the amount were found for alkaline noodle textural
characteristics maximum cutting stress and maximum compression force. 15
Brightness of the noodle is, however, inversely related to flour protein requiring
a compromise between the noodle texture and appearance. Flour ash content and
color grade were found to be positively correlated with the noodle yellowness,
b*. Patent flours yield brighter noodles while straight grade flours yield yellower
but duller noodles. 18
Starch pasting characteristics of the flour were found to be correlated with
textural attributes. 18,23,33,34 They found that breakdown (paste stability) was
positively correlated with noodle smoothness and negatively correlated with
firmness. Flour peak viscosity’s usefulness for texture prediction is still
debatable 21,34,35 although inactivation of amylase with silver nitrate improved
the correlation greatly (see Table 7.4). 21 Flour swelling volume has also been
found to be inversely correlated with alkaline noodle texture. 21 Reconstitution
studies showed that the eating quality, particularly the elastic texture of the