Mean values for each characteristic followed by different letters within a column differ significantly (P = 0.05)
Rice Noodles: Materials, Processing and Quality Evaluation
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2.2 Water
Water is considered to be the second key raw
material used in noodle making after flour. The
proportion of water used in noodle making should
be optimum (30–35%) in order to optimally hydrate
the flour for making dough of proper consistency
[2]. Addition of excess water results in soggy
dough, while too little water creates difficulty in
dough formation and sheeting [51]. It furnishes
the required medium for all the biochemical and
physicochemical reactions in transforming the raw
components into finished products. It can dissolve
the water soluble components prior to mixing.
The water used for making noodle should meet
the sanitary requirements to produce high quality
products [1, 2, 52].
Water varies in characteristics depending on its
origin. Surface water usually contains higher level
of chemical, microbial and organic contaminants
compared to ground water. However ground water is
relatively richer in dissolved inorganic substances.
Water are characterized as either hard, soft, saline
or alkaline depending upon the amount and types of
mineral salts available in natural water, which has a
pH value between 5.8 and 8.6 [1]. All these types of
water affect flour hydration, starch gelatinization,
sheeting process and texture of noodles. Hard water
is not used generally because it reduces the water
retention capacity of the flour. The available ions in
hard water substantially affect the gelatinization of
starches in subsequent steaming or boiling process.
While, very soft water yields sticky and soft dough
sheets. Low to medium hard water is considered
desirable for noodle processing. The high alkaline
water is due to the presence of magnesium and
calcium ions. After boiling, the pH of alkaline
water rises to 9 due to the decomposition of
bicarbonates upon heating to form the subsequent
carbonates. Therefore, alkaline water is not used
in the processing of noodles, particularly for
manufacturing boiled noodles. Organic acids
i.e. acetic, citric, lactic, malic or citric acids are
added sometimes to adjust the pH of water for the
preparation of boiled noodles [1-2, 9, 52].
2.3 Salt
Salt is another basic ingredient which is used in
noodle preparation, which is added up to 1-3% of
flour weight. However, about 8% of salt could be
used in the formulation for processing of boiled
Udon and hand-made noodles. Salt play three major
role in noodle processing. The most important
function is its tightening and strengthening role
in dough gluten that is attributed to its inhibitory
effect on proteolytic enzymes. While, other
evidences shows a direct relationship between
protein and salt. It substantially enhances dough
sheeting properties, particularly at a higher water
absorption index. The next important role that salt
contribute is the improvement of texture and flavor.
In addition of providing salty taste, it also acts as
a flavor enhancer in many other foods. It imparts
fullness to the “mouth-feel” and masking possible
off-taste. Salt significantly reduce the cooking
duration and provide elastic and softer texture. The
third important role of salt is its inhibitory effect
on microbes and various enzymes. Salt retard the
spoilage and oxidative reactions at high humidity
and temperature, thereby prolonging the shelf life
of products. Higher concentration of salt in noodle
formulation also reduces the drying rate [1].
However, by considering the consumer
preference, alkaline salt are used alone or in
combination with various salts. Potassium and
sodium carbonates are the most commonly used
alkaline salts. While, other alkaline reagents i.e.
bicarbonates and sodium hydroxide are also added
occasionally. Alkaline salts are added at a rate of 0.5
to 1.5% in noodles having strong alkaline flavor,
while added at a rate of 0.1 to 0.3% in few noodle
types for the purpose of improving their quality [1].
The yellowish color of alkaline noodles is provided
by the natural pigments such as flavonoid present
in flour, which behave as color in acidic medium,
while turn to yellow in alkaline medium. A
greenish-yellow color is given to the noodles by the
incorporation of potassium carbonate that also have
less reflectance as compared to noodles prepared by
the addition of sodium carbonate. However, sodium
hydroxide gives more yellow and brighter noodles.
Addition of alkali gives inelastic dough that can
hardly be compressed during sheeting. It provides
a firm texture compared to noodles made from only
salt [1, 28].