Cereals processing technology

98 Cereals processing technology
5.6 Rice noodles, parboiled and quick-cooking rice
In China, rice noodle is called mi fen and in Japan, harusame. Mi fen is made
from rice only; harusame may be made from mung bean, starch, or rice or a
mixture of these. Rice noodles are consumed in the form of soups. The rice
noodle soups are usually prepared from mi fen, water, meat or chicken, green
vegetables, soy sauce, and Chinese onion for an attractive aroma. The product is
highly attractive in sensory quality because of the special texture, aroma, and
taste. The conventional processing method is limited to sun drying. There are a
few exceptions using hot air drying or infrared drying methods. A short
description for the manufacture of mi fen follows.
Nonglutinous rice is soaked in water for 3–5 h, ground, and mashed into a
rice paste, which is then pressed in a bag to force out the excess water. The
product is steamed for 5–80 min. The optimum condition is to reach 80%
gelatinization of the rice starch. The product is then kneaded in a machine and
shaped into a column from which raw rice noodle is extruded. The raw rice
noodle is steamed for 30 min, dipped into a seasoning solution, cut, and put into
racks for hot-air drying. The final product is then cooled and packaged. Mi fen is
a dehydrated product. It can be kept for 1–2 years at room temperature after
packaging and sealing in plastic films. To attain the quick reconstitution
characteristics, mi fen should be dried in a hot air current at 80ºC to prevent
reverting the gelatinous (alpha) starch to the beta form. There are fresh mi fen in
various forms, packaged in plastic films available in the supermarkets.
Parboiling is a hydrothermal procedure in which the crystalline form of starch
present in the paddy rice is converted into amorphous form. This is
accomplished by soaking the paddy rice in warm water at 65ºC for 4–5h,
followed by steaming under pressure in a continuous apparatus, drying, and
milling the dried paddy rice. The parboiling process produces physical and
chemical changes of the rice kernel with some economical and nutritional
advantages. The process is quite popular in India, Brazil, the United States, Italy,
and other countries.
The major objectives of parboiling are to (a) increase the total and head yield
of the paddy, (b) reduce the loss of nutrients during milling, (c) salvage the wet
and damaged paddy, and (d) prepare the rice according to the requirements of
the consumers and rice processors.
The changes occurring in the parboiling process are as follows:
• the starch grains embedded in a proteinaceous matrix are gelatinized and
expanded until they fill up the surrounding air spaces,
• the protein substances are separated and sink into the compact mass of
gelatinized starch, becoming less liable to extraction
• the water-soluble vitamins and mineral salts are spread throughout the grain.
The riboflavin and thiamin content are four times higher in parboiled rice than in
milled rice.