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Consumption of processed rice products is probably highest in Japan, where it accounted for about 9.5 percent of total rice consumption in 1987 (4.8 percent sake, 1.0 percent miso, 2.0 percent crackers, 1.0 percent flour and 0.4 percent each packaged rice cake and boiled rice products), (Hirao, 1990). In comparison, processed rice products have accounted for about 2 percent of rice consumption in the Philippines (Food and Nutrition Research Institute, 1984), about 1 percent (as noodles) in Malaysia (FAO, 1985) and over I percent in Thailand (Maneepun, 1987).
In countries such as Japan and the Republic of Korea where per caput consumption of boiled rice is decreasing, maintenance of rice consumption is being pursued through the development of new products and the improvement of traditional products in order to maintain total rice production. Japan has the widest range of convenience rice products, including automated cooking equipment for catering (Juliano and Sakurai, 1985). Many national programmes are also looking into the improvement of the quality and shelf-life of traditional rice products (FAO, 1985). Japan's super-rice programme will incorporate selected preferred characteristics of foreign rice into the new Japanese rices (Yokoo, 1990).
Processed rice products may be derived from rough rice, brown rice, milled rice, cooked rice, brokers, dry-milled flour, wet-milled flour or rice starch (Juliano and Hicks, 1993), (Figure 5). The nutrient composition of some rice products is summarized in Table 44.
Precooked rice is used for rice-based convenience food products in which nonrice ingredients are packed separately and mixed only during heating. Retort rice in Japan is made by hermetically sealing cooked non-waxy and waxy rice in laminated plastic or aluminium-laminated plastic pouches and pasteurizing at 120°C under pressure (Juliano and Sakurai, 1985; Tani, 1985). Steamed waxy rice with red beans accounts for 80 percent of retort rice in Japan, with an annual production of 8 030 t in 1983 (Tani, 1985) and 4 264 t in 1986 (Iwasaki, 1987). An aluminium-laminated plastic pouch is warmed directly in hot water for 10 to 15 minutes, while plastic pouches may be punctured and heated in a microwave oven for 1 to 2 minutes.
FIGURE 5 Chart of processed rice products based on starting rice raw material
Frozen cooked rice packed in airtight plastic pouches had a production figure of 10 841 t in 1983 in Japan (Tani, 1985); 22 575 t were produced in 1986 (Iwasaki, 1987). Deep freezing without dehydration is the best condition for keeping cooked rice from retrograding (hardening). Frozen rice produced in cooking centres is delivered to chain restaurants where it is heated in microwave ovens and served to customers.
TABLE 44 - Nutrient composition per 100 g of selected rice products
|Instant rice, US||9.6||362||7.5||0.44||-||3.5|
|Rice, granulated, USa||7.4||383||6.0||0.42||0.11||5.8|
|Kaset rice-soybean infant food, Thailanda||5.2||401||11.0||0.2||0.4||1.0|
|Baby cereals, rice-based, UKa||4.9||386||10.9||1.60||1.20||23.0|
|Am, thin rice gruel, Philippines||95.9||17||0.1||0.02||0.02||0.4|
|Rice gruel, Philippines||91.5||30||0.6||0.01||0.01||0.1|
|Arroz caldo, rice gruel, Philippines||83.8||63||2.0||0.02||0.03||0.4|
|Bihon, rice noodles, Philippines||12.4||364||5.0||trace||0.01||0.2|
|Fermented rice/black gram idli, India||45.0||220||7.6||0.32||0.30||0.9|
|Puto, fermented rice cake, Philippines||46.6||214||2.8||0.01||0.01||0.4|
|Chinese waxy rice cake, UK||29.8||290||3.5||trace||0.02||0.9|
|Bibingka, rice cake, Philippines||41.5||234||3.6||0.12||0.05||0.6|
|Waxy rice bibingka, Philippines||36.8||256||2.8||0.03||0.01||1.1|
|Kutsinta, rice cake with lye, Philippines||58.9||167||1.4||trace||0.01||0.2|
|Suman, waxy rice cake with lye,Philippines||52.3||191||3.2||trace||0.02||0.5|
|Suman sa ibos, waxy rice cake with coconut milk, Philippines||57.5||171||3.1||0.01||0.01||0.3|
|Tikoy, waxy rice cake, Philippines||37.7||250||2.5||0.02||0.02||0.4|
|Puto bumbong, purple waxy rice cake,Philippines||38.5||251||3.5||0.03||0.01||0.4|
|Palitaw, waxy rice preparation,Philippines||51.8||206||2.6||0.04||0.02||0.7|
|Kalamay, waxy rice preparation with coconut syrup, Philippines||48.2||208||2.7||0.01||0.01||0.3|
|Espasol, waxy rice product, Philippines||25.8||312||4.0||0.06||0.04||1.1|
|Tamales, rice flour preparation,Philippines||75.2||100||1.3||0.01||0.02||0.4|
|Puffed rice, US.||3.7||399||6.0||0.44||0.04||4.4|
|Puffed rice, non-waxy, sweetened||5.6||385||4.5||0.01||0.14||1.6|
|Puffed rice, presweetened, with cocoa, USa||3.4||401||4.5||0.42||0.06||6.3|
|Pinipig, flattened parboiled waxy rice,puffed, Philippines||3.3||392||3.1||trace||0.04||2.0|
|Puto seko, toasted rice bread,Philippines||4.8||388||6.0||0.06||0.02||0.5|
|Rice pudding, canned, UK||77.6||89||3.4||0.03||0.14||0.2|
|Chicken with rice soup,condensed, US||89.6||39||2.6||trace||0.02||0.6|
|Japanese sake rice wine, 32 proof||78.4||134||0.5||0||0||0|
|Chinese rice wine, 34 proof||79.1||132||0||trace||0.01||0.12|
|Rice flour, UK||11.8||366||6.4||0.10||0.05||2.1|
a With added vitamins and minerals.
Sources: Food and Nutrition Research Institute, 1980; Watt and Merrill, 1963; Luh and Bhumiratana, 1980; Holland, Unwin and Buss, 1988.
Quick-cooking rices are those that require significantly less cooking time than raw milled rices (15 to 25 minutes). Various methods are employed to fissure raw rice or to dry cooked rice to produce a porous structure. Dry-heat methods include heating milled and brown rice with 57 to 82°C air for 10 to 30 minutes or with 272°C air for 17.5 seconds to fissure the grain. Japanese companies heat brown rice in a countercurrent hot air stream at 105 to 130°C for 30 minutes and quickly cool it to below 30°C (Juliano and Sakurai, 1985). Parboiled brown rice may be made quick-cooking by scouring about I percent by weight of the pericarp to remove the outer water-impervious layer (Desikachar, Raghavandra Rao and Ananthachar, 1965). Precooked quick-cooking rice processes include soak-boilsteam-dry, gelatinize-dry-puff, gelatinize-roll or bump-dry, freeze-thaw, gun puff, freeze-dry and chemical treatments (Roberts, 1972).
Pregelatinized or "alpha" rice production in Japan was 13 900 t in 1983 (Tan), 1985) and 14 500 t in 1986 (Iwasaki, 1987). Cooked rice is quickly dried by heated air to fix the starch in an amorphous state at about 8 percent moisture. Gelatinized rice is used as an emergency food and as rations in ships and mountain climbing because of its long shelf-life (three years), (Imai, 1990) and light weight (Juliano and Sakurai, 1985). It is consumed after hydration, cooking or warming for about 10 minutes and standing for about 15 minutes. Freeze-dried rice reconstituted by adding hot water to it best approximates cooked rice. Japanese instant rice gruel is prepared from pregelatinized brown-rice flour or flattened grains by adding hot water or cooking over low heat for several minutes and may be used as a weaning food.
In Taiwan Province (China), two kinds of dried cooked rice are produced commercially. One is a Cantonese-style rice congee made from non-waxy (lowamylose) milled-rice brokers, washed, ground in a hammer mill with a 5-mm screen, precooked with six times the volume of water, drum-dried for 3 minutes with a steam pressure of 5 kg/cm2 and a clearance of 1.5 mm, flaked, mixed with dried cooked meat, vegetables, salt, monosodium glutamate and other flavourings and packed in pouches. The other product is guo-ba, a thin block of dried cooked waxy rice. Waxy rice is washed, soaked, cooked in a rice cooker, hand-spread in a thin uniform 0.6 cm layer on teflon-coated perforated trays, baked over a flame at 135°C for 40 minutes or at 165°C for 15 minutes, cut into 6 x 6 cm blocks and sundried to about 12 percent moisture. The guo-ba may be packaged for future use, may be further flavoured and fried, may be used as a ready-to-eat snack or breakfast food or may be added as an ingredient in cooked dishes. Both products involve spreading the cooked rice into layers by hand, which is both time consuming and a potential source of contamination.
Dry precooked rice cereal is produced by preparing and cooking a cereal slurry, which is then dried in a double-drum atmospheric dryer, flaked and packed (Brockington and Kelly, 1972). The slurry solids, drum speed and temperature and spacing between drums are carefully controlled. Hydrated precooked and readyto-eat infant foods must have the right consistency, soft enough to be swallowed easily but thick enough to feed without spilling. Malt and fungal a-amylase may be added to control the quantity of liquid required to reconstitute the dried cereal and to sweeten it by partial hydrolysis of the starch. Rice-based weaning foods are popular in Southeast Asia, such as the Kaset extrusion-cooked rice and full-fat soybean formulation (Luh and Bhumiratana, 1980). Heat-sensitive ingredients such as milk are preferably added after extrusion, to avoid lysine and cysteine degradation of the protein.
Flat and extruded round noodles and rice paper are traditionally prepared from wet-milled flour that has been ground using either a stone or a metal mill. The starting material is brokers with a low fat content, preferably freshly milled from aged rice with a high apparent amylose content and a hard gel consistency.
To make flat rice noodles, a wet-milled rice batter with a consistency of 42 percent rice by weight is placed on a noodle-making machine until the drum is half immersed. The smooth drum is then slowly rotated. The adhering batter is scraped off by a stainless steel sheet set at about a 45° angle and flows onto a moving taut cotton or stainless-steel conveyor belt that carries it into a steam tunnel for 3 minutes for gelatinization (to 62 percent moisture), (Juliano and Sakurai, 1985; Maneepun, 1987). The sheet dips momentarily into peanut oil before it is folded and cut into appropriate sheets (50 x 50 cm) for direct sale as fresh noodle. Very little starch degradation occurs in the process.
Rice paper and egg roll wrapper are also prepared from wet-milled high-amylose rice batter in Viet Nam, Thailand and Taiwan. A measured volume of rice batter, with the proper consistency, is poured with a flat shallow ladle over taut cheesecloth on top of a steamer. The batter is spread over the whole surface by a circular motion of the ladle and steamed until gelatinized. The sheet is then removed with a rolling motion onto a rolling pin and unrolled onto a slottedbamboo drying tray. Rice paper is thinner than egg roll wrapper and is used as translucent edible candy wrapper. The egg roll wrapper may have some added salt.
A cooked rice slurry with added food colours is poured onto various leaf surfaces, dried and peeled off and used as colourful decorations for homes during the annual May 15 festival at Lucban, Quezon in the Philippines. These edible decorations, kiping, retain the vein patterns of the various leaves on to which they are poured.
Traditionally, extruded noodles (bihon, bijon, bifun, mehon or vermicelli) are prepared from aged high-amylose brokers by wet-milling the steeped rice, kneading it into fist-sized balls, surface-gelatinizing the flour balls (about 500 g) in a boiling water bath until they float, remixing, extruding through a hydraulic press with a die, subjecting the extruded noodles to heat treatment for surface gelatinization, soaking in cold water and sun-drying in racks (Juliano and Sakurai, 1985). Machines in Thailand knead the flour into cylinders that are steamed in portable racks and mixed mechanically into the extruder. Extruders may also be used to cook end kneed premoistened dry-milled flour and then extrude it as noodle at the end of the barrel. Considerable starch degradation occurs during extrusion, such that the gel consistency changes from hard to soft. Protein quality deteriorates very little.
Fermented extruded fresh rice noodle is quite popular in Thailand. Brokens are soaked for three days for fermentation, which reduces the pH from 7 to 3.5, with Lactobacillus spp. and Streptococcus spp. (Maneepun, 1987) and are then processed in the same manner as the unfermented noodle.
Protein decreases from 1.54 percent after one day of fermentation to 1.14 percent after three days at 70 percent moisture.
During wet milling, water-soluble nutrients and damaged starch are lost in the filtration step. Nutrient losses include vitamins, minerals, free sugars and amino acids, water-soluble polysaccharides and protein (albumin) and fat. The wastewater poses a pollution problem. Many Philippine extruded noodle plants use maize starch to minimize the pollution, but maize starch noodle has lower nutritional value (<1 percent protein) than rice noodle.
Wet-milled non-waxy or waxy rice flour may be kneaded with water and converted to sweetened rice cake by adding sugar and other ingredients before steaming. A yeast-fermented steamed rice cake (puto) is produced in the Philippines, for which aged, intermediate-amylose rice yields the greatest volume expansion and optimum softness (Perez and Juliano, 1988). Nenkau is a traditional Chinese rice cake and is basically of three types: a sweetened cake made of waxy rice and sugar; a savoury cake with radish, made from high-amylose rice mixed with crushed radish; and a fermented rice cake, made of fermented rice dough of highamylose rice and sugar.
Idli (rice dumpling) and dosai (rice pancake) are prepared in India from a mixture of parboiled milled rice and black gram (Phaseolus mungo), about 3:1 by weight, typically as breakfast foods (Hesseltine, 1979; Steinkraus, 1983). Rice and decorticated black gram are separately washed, soaked 5 to 10 hours in 1.5 to 2.2 times by weight of water and wet-milled separately to give a coarse (0.6 mm) rice flour and a smooth, gelatinous gram paste. The flour and paste are mixed together with 0.8 percent salt and the thick batter is fermented overnight, steamed (idli) or fried (dosai) and served hot. Ingredients added to idli for flavour include cashew nut, ghee, pepper, ginger, sour buttermilk and yeast. Dosai usually contains less black gram. The batter quality of idli is attributed to the globulin protein and the arabinogalactan of the black gram (Susheelamma and Rao, 1979). Parboiled highamylose rices are suitable for idli. During fermentation, B vitamins and vitamin C increase (Soni and Sandhu, 1989) and phytate is about 50 percent hydrolysed.
A Philippine rice cake, bibingka, is made from non-waxy and waxy rice flour (wet-milled) with sugar and coconut milk, baked in a banana-leaf lined pan in a charcoal stove with live charcoal on top until brown. Another rice cake, puto kutsinta, is an unleavened cake textured like a stiff pudding and is prepared from wet-milled rice flour with sugar and lye.
Japanese rice cake or paste (mochi) is traditionally prepared from waxy milled rice by washing the milled rice, steaming at 100°C for about 15 minutes to a 40 percent moisture content, grinding (kneading or using a mortar and pestle), packing in plastic film, pasteurizing for 20 minutes at 80°C and cooling (Juliano and Sakurai, 1985). Recently, gelatinized waxy-rice flour has been directly manufactured by extrusion cooking; it has diverse applications, including mochi. Mochi is usually sliced into pieces (such as cubes), toasted and seasoned with soy sauce or wrapped and eaten as a snack. Preferred waxy rices have a final starch GT of 66 to 69°C (Palmiano and Juliano, 1972). Ready-to-eat mochi is pasteurized under 95°C in packaged containers (Tan), 1985). Annual consumption in Japan was 42 000 t in 1983 and 52 305 t in 1986 (Iwasaki, 1987).
Traditional Philippine waxy-rice snack foods or desserts include rice cakes (suman) made from milled rice. Suman sa antala and suman sa ibos are cooked with coconut milk and salt. Suman sa antala is wrapped in heat-wilted banana leaves and steamed for 30 to 35 minutes, but for suman sa ibos the waxy rice/coconut milk mixture is packed loosely into nipa or palm leaves (ibos) and boiled for 2 hours or until done. In suman sa lihiya, the steeped waxy rice is treated with lye,, wrapped in banana leaves and boiled for 2 hours or until done. Suman sa ibos is usually served with sugar, while suman sa lihiya is served with grated-coconut and sugar. Low-GT waxy rices are preferred for these cakes. Wetmilled purple waxy rice is added to waxy rice in preparing puto bumbong, wherein the rice flour is cooked by steaming in bamboo cylinders. Food colouring is now used to obtain the purple colour of the product, which is also eaten with grated coconut and sugar. Palitaw is made from a flattened wet-milled batter of waxy rice dropped into boiling water; after the cakes float they are dropped into cold water to prevent them from sticking to each other. They are drained and served with grated coconut and pounded sesame seeds. Espasol is made from coconut milk and sugar syrup to which cooked waxy rice is added, followed by toasted and powdered waxy rice. The paste is rolled with a rolling pin and cut into various shapes. Rice powder is sprinkled over the paste to prevent sticking. Tamales contains toasted, ground rice and a mixture of peanuts, sugar, spices and meat which is cooked until thick enough to hold its shape. It is then wrapped in banana leaves and steamed for 2 hours.
The Japanese rice pudding uiro consists of waxy rice flour, cornstarch, sugar, water and flavourings that are mixed and steamed for 60 minutes at 100°C and served with sweet bean curd, green tea, coffee, cherries and other fruits (Juliano and Sakurai, 1985). Low-amylose, short- to medium-grain rices are used in preparing Chinese rice pudding (Li and Luh, 1980). The rice is cooked in boiling water, strained and mixed with milk before the completion of cooking. Egg yolk, sugar, vanilla and light cream are added together with a variety of fruit combinations. Canned rice pudding in a milk base with added fruit has been available in Australia and the United Kingdom for more than two decades.
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