Cereals processing technology

96 Cereals processing technology
5.4 Processing issues
Rice is one of the world’s most important cereals for human consumption. In the
densely populated countries of Asia, as much as 80–90% of the daily caloric
intake of some people is derived from rice. It is also consumed in the form of
noodles, puffed rice, breakfast cereals, rice cakes, fermented sweet rice, and
snack foods made by extrusion cooking. Rice is also used in making beer, wine,
and vinegar.
5.5 Rice snack foods
In most Asiatic countries, rice cereals are consumed as cooked rice and are
served simultaneously with prepared vegetable dishes, poultry, beef, seafood,
among others. There are many kinds of snack foods, prepared for more attractive
taste, texture, and aroma. They are served in some cases for special occasions,
for some special tastes, and for convenience.
Some rice snack foods are made from either glutinous rice (sweet or waxy
rice) containing largely amylopectin (98% of total starch), but very little
amylose (less than 2% of total starch), while others are made from both types. A
typical glutinous rice flour contains 11.0–13.5% moisture, 1% ash (max.), 75–
80% total starch, 5.5–6.5% protein, and 0.5% total fat. Glutinous rice flour is
often used in making snack foods since the sticky characteristics of high
amylopectin content are necessary in many specialty rice foods. Another reason
for application of glutinous rice in baked and popped snacks is that glutinous
rice flour expands readily and produces a more porous texture.
5.5.1 Rice cracker processing
Rice cracker is a Japanese snack food made from rice. Arare and senbei are the
traditional rice crackers in Japan. Rice crackers made from glutinous rice are
generally called arare or okaki. Rice crackers made from nonglutinous rice are
called senbei. They have a harder and rougher texture than arare. In choosing
between glutinous or nonglutinous rice, one has to pay attention to uniformity in
quality, rate of water absorption, extent of refinement, and absence of
objectionable odors and taste. In order to improve the flavor and appeal of snack
foods, seaweed, sesame, red peppers, sugar, pigments and spices are added.
A flowchart for processing arare rice crackers from glutinous rice is presented
in Fig. 5.1. Glutinous rice is washed in a washing machine and soaked for 16 h in
water at temperatures below 20ºC. After draining, the rice, which contains about
38% moisture, is crushed by rollers into fine powder, passed through an 80-mesh
sieve, and steamed for 20 min. After cooling for 2–3 min, it is kneaded three times
in a special machine. The kneaded cake is put in a cake vessel, quick-frozen, and
kept at 2–5ºC for 2–3 days for hardening. The cake is cut into various shapes and
dried by hot air at 45–75ºC to a final moisture content of 20%. The cake is coated