Utilization of rice grains and other parts of rice plants in Vietnam

UTILIZATION OF RICE GRAINS AND OTHER PARTS

OF RICE PLANTS IN VIETNAM

Nguyễn Văn Ngưu

Rice grains contained considerable amount of energy, protein, and vitamin needed by human being. After cooking, milled paddy grains or hạt gạo produce cooked rice or cơm and milled glutinous rice grains or hạt nếp produce cooked sticky rice or xôi. Cooked rice and cooked sticky rice are principal foods of Vietnamese. Vietnamese also developed different ways and methods to process milled paddy grains and glutinous rice grains into different food products to enrich their life. Some Vietnamese rice-based foods are popular around the world. In addition to milled rice grains, rice crop also produced rice straw, rice husks and hulls, rice brans, and broken rice after series of harvesting and postharvest operations. Vietnamese also had turned these products into valuable products for life. The following pages present the nutrient from rice, different products of milled rice grains, and the utilization of other products of rice crops.

I. NUTRIENTS FROM RICE

Vietnamese regularly cook well milled or white rice and sometimes brown rice for daily food. On the average, milled rice contains about 80% starch, 7.5% protein, 0.5% ash and 12% water. The consumption of 60 kg of milled rice grains (or 100 kg of rough rice grains) per year provides a person with about 668 kcal, 12.23 g protein, and 1.23 g fat per day. Protein content in milled rice is slightly lower than that in brown rice. Also, crude fat, crush ash, crush fiber, and total dietary fiber are lower in milled rice.

Brown rice is a rich source of vitamin B complex, thiamin, riboflavin, niacin, panthothenic acid, foliate, and vitamin E, but it is poor in iron (Fe) and zinc (Zn) and has no vitamin A, C, and D. Brown rice has the highest energy content, but lowest protein content and total dietary among cereal grains. It has also lowest tannic acid content in non-pigmented grains. Regular consumption of brown rice is associated with health benefits including reduced risk of coronary heart disease and several forms of cancer. Phytic acid, tocopherols, oryzanols, and vitamins in rice grains are antioxidants. Brown rice consists, on an average weight, of 6-7% bran, 90% endosperm and 2-3 % embryo.

After complete milling, about 60 kg of milled rice, 10 kg of broken grains, and 10 kg of bran are obtained from 80 kg of brown rice. The nutrient content of brown rice and well-milled rice is shown in Table 1.

Table 1 Content of energy, nutrient, vitamin and mineral in 100 g of well-milled and brown rice (adopted from Juliano and Villareal 1993)

Well-milled Rice

Brown Rice

Energy content (kcal)

349-373

363-385

Crude protein (g)

6.3-7.1

7.1-8.3

Crude fat (g)

0.3-0.5

1.6-2.8

Crude ash (g)

0.3-0.8

1.0-1.5

Crude fiber (g)

0.2-0.5

0.6-1.0

Available carbohydrate (g)

77-89

73-87

Total dietary fiber (g)

0.7-2.3

2.9-4.0

Water-insoluble fiber (g)

0.5

2.0

Sugar (g)

0.2-0.5

1.9

Phytic acid (g)

0.1-0.2

0.4-0.9

Phenolics (g catechin)

0.01-0.02

0.01-0.02

Thiamin (mg)

0.02-0.11

0.3-0.6

Riboflavin (mg)

0.02-0.06

0.04-0.14

Niacin (mg)

1.3-2.4

3.5-5.3

Panthothenic acid (mg)

1.0

1.4

Pyridoxine (mg)

0.2

0.5

Folate

trace

trace

Vitamin E, tocophenol (mg)

<0.01-0.30

0.8-2.5

Calcium (mg)

10-30

10-50

Phosphorus (g)

0.08-0.15

0.17-0.43

Phytic acid (g)

0.02-0.07

0.13-0.27

Iron (mg)

0.2-2.8

0.2-5.2

Magnesium (mg)

20-50

20-150

Potassium (mg)

70-130

60-280

Sodium (mg)

0.5-8.6

1.7-34.0

Zinc (mg)

0.6-2.3

0.6-2.8

Copper (mg)

0.2-0.3

0.1-0.6

Manganese (mg)

0.6-1.7

0.2-3.6

Selenium

trace

trace

II. FOOD DISHES FROM MILLED RICE

On the average, after all postharvest operations, one ton of paddy or raw rice grains produces about 650 to 680 kilograms of milled rice grains (La Van Chu, 1990). In the early time of their history, Vietnamese cooked milled glutinous rice or nếp, but today they cooked milled rice or gạo for daily food. Vietnamese also utilized milled glutinous rice or nếp and milled rice or gạo to produce different foods or food dishes.

II.1 Boiled/Steamed Rice or Cơm and Its By-Products

  • Boiled/Steamed Rice or Cơm: Vietnamese eat boiled/steamed rice or cooked rice two to three times a day. It is estimated that about 50 grams of milled rice or gạo could produce enough cooked rice or cơm for a grown-up/mature Vietnamese to eat in a meal. Milled rice grains are washed, put into a pot, and cooked in water for about 20 minutes. The ratio of rice grain/water is about 1/1 to 1/1.5 depending the grain type. Cooked rice is served with other dishes from vegetable, meat, fish.
  • Fried Rice or Cơm rang/Cơm chiên: Fried rice is the cooked rice that is fried with ingredients such as eggs, sausage, cooked meats, and others. It is a favorite of many Vietnamese. It is served as main course in daily meal, but in party buffet or banquet, it is served at the last course.
  • Rice porridge/congee or Cháo: It is a simple dish made from just milled rice and water. The rice is simmered in a pot with water until the mixture disintegrates.  It is consumed during breakfast and the names of the dishes vary with the added ingredients used in their preparation, for example cháo gà is chicken rice porridge.
  • Cơm Hến is a dish of leftover steamed/boiled non-glutinous rice with-mussels. It is a popular rice dish in Huế City.
  • Cơm Nắm: It is dish in which boiled/steamed rice is compacted into shapes
  • Cơm Lam or BambooTube Rice: It is a special rice dish in Central Highland and Northwestern Mountainous Region. Washed milled glutinous rice and other ingredients are mixed and placed in a bamboo trunk and grilled to cook over fire.

II.2 Steamed/Boiled Glutinous Rice or Xôi

  • Xôi: It is a Vietnamese dish of steamed/boiled milled glutinous rice. Probably, xôi was the main food in the early years of Vietnamese history. Today xôi is still a daily main dish for minority ethnic groups in Central Highland and mountainous regions in northern Vietnam. Also, Vietnamese today still offer a dish of xôi to their ancestors during death anniversary. Old mothers also prefer xôi than cơm.
  • Xôi ngọt: It is xôi with added vegetative ingredients such as grains, beans, leaves
  • Xôi mặn: It is xôi with fish, meat, eggs as added ingredients.

II.3 Rice Cakes or Bánh

Milled glutinous rice or gạo nếp are also used to make different types of cakes or bánh in Vietnamese. Following are some popular cakes or bánh made from gạo nếp or milled glutinous rice:

  • Bánh chưng is a traditional and popular rice cake in Northern Vietnam. Milled glutinous rice with filling of mung bean, pork and other ingredients are wrapped in dong (Maranta leuconeura ) leaves into a square shape and boiled to cook. It is an essential element of the family altar in Northern Vietnam during Vietnamese New Year.
  • Bánh tét is a traditional and popular rice cake in Southern Vietnam. Milled glutinous rice with filling of mung bean, pork and other ingredients are wrapped in banana leaves into a long-cylindrical shape and boiled to cook. It is an essential element of the family altar during Vietnamese New Year in Southern Vietnam.
  • Bánh Ú or Pyramidal Glutinous Rice Cake is made from milled glutinous rice without filling or sugar filling wrapped in banana leaves in Northern Vietnam and from milled glutinous rice with pork, mung bean and duck egg filling wrapped in banana leaves in Southern Vietnam, and boiled to cook. In Northern Vietnam it is also called as bánh gio, bánh ú nếp tro and used during Đoan Ngọ Festival in May of Lunar Calendar.
  • Bánh khúc or xôi khúc or xôi cúc is popular dish in northern delta. It is made with milled glutinous rice, pork and rau khúc (Gnaphalium affine), a vegetable found only in the area, wrapped in banana leaves and boiled/steamed to cook. They are usually made in March and April, the season of rau khúc
  • Bánh cáy is popular dish in Thái Bình Province. It is made from milled glutinous rice, sugar, gac fruit or gardenia, sesame, carrots, mandarin orange peel, and lard. The mixture is roasted and ground, then put into a square box.

III. FOOD DISHES FROM RICE FLOUR, RICE PAPER, AND RICE NOODLE

Milled rice, whole and/or broken, could also be ground, wet or dry, to make rice flour. Rice flour is used for production of rice noodles and edible rice papers. Noodles may be either extruded/round or sheet/flat. Rice noodles and edible rice papers are based materials for the preparation of a variety of popular dishes in Vietnam

III.1 Some Popular Foods Made from Rice Flour

  • Bánh giầy: It is a traditional and popular rice cake in Northern Vietnam. Flour of glutinous rice with filling of mung bean and other ingredients are wrapped in banana leaves and boiled to cook. It is a white, flat, round cake with tough, chewy texture. It is an essential element of the family altar during Vietnamese New Year in Northern Vietnam. It is called sometimes as bánh dầy or bánh dày.
  • Bánh gai: It is popular rice cake in northeastern region of Vietnam. It is made from flour of glutinous rice and the leaves of the “gai” tree or Boehmeria nivea. The dried leaves of gai tree are boiled, ground into small pieces, then mixed with glutinous rice, and wrapped in banana leaf and boiled to cook. The filling is made from a mixture of coconut, mung bean, peanuts, winter melon, sesames, and lotus seeds.
  • Bánh cam: It is a popular fried rice ball in Southern Vietnam. It is made from glutinous rice flour, which is formed in a ball with sweetened mung bean paste as filling and coated with sesame seed. The ball is fried to cook.
  • Bánh ít: It is a rice cake/ball made from glutinous rice flour with mung bean or coconut as filling wrapped in banana or gai leaves and boiled to cook. It has a triangle form in the North and a round cylinder form in the South. It is also called small stuffed glutinous rice flour balls. Bánh ít lá gai is popular in Bình Định Province.
  • Bánh nậm: It is popular rice cake in Huế. It is made with flour of non-glutinous rice with shrimp powder or mung bean as filling, wrapped in banana leaves, and boiled/steamed to cook.
  • Bánh bèo: It is popular rice cake in Huế. It is a small steamed rice cake or rice pancake from flour of non-glutinous rice. It is white in color and typically features a dimple at center, which is filled with ingredients including chopped dried or fresh shrimp, scallions, and mung bean.
  • Bánh bột lọc: It is popular rice cake/dumplings in Huế. It is made with flour of glutinous rice batter stuffed with shrimp and ground pork, wrapped in banana leaves and boiled to cook.
  • Bánh ống lá dứa: It is popular dish of Khmer people in Sóc Trăng and Trà Vinh Provinces. They are made from rice flour, Pandanus amaryllifolius leaf extract, sugar, and coconut milk/water and steamed to cook. Coconut threads and roasted sesame seeds are usually added to cooked Bánh ống lá dứa
  • Bánh tai yến: It appears as the ears of apodiformes bird or swift, which is yến in Vietnamese. They are made from rice flour, sugar, some tapioca flour and fried to cook.
  • Bánh đúc: In Northern Vietnam, they are made from non-glutinous rice flour or corn flour and typically garnished with ingredients such as ground pork, grilled ground shrimp, fried onions, sesame seeds, salt, peanuts, lime juice, and soy sauce or fish sauce. In southern Vietnam, they are made from non-glutinous rice flour and take the form of gelatinous blocks that are often colored green by the addition of Pandanus amaryllifolius leaf extract. They are cooked by boiling the ingredients and allowing them to cool, solidifying into a jelly-like sheet that is then cut into blocks.
  • Bánh khọt: It is popular dish in Bà Rịa–Vũng Tàu Province. It is made from rice flour with shrimp filling and fried to cook. It is served with assorted fresh vegetable, fresh chili, and shrimp sauce.
  • Bánh trôi: It is a popular dish in Northern Vietnam. Glutinous rice flour is mixed with a small amount of water to form balls and is then cooked and served in boiling water.
  • Bánh tẻ or Bánh răng bừa: It is a popular dish in Northern Delta and Thanh Hóa Province. It is made from rice flour wrapped in dong (Maranta leuconeura) leaves and boiled to cook.
  • Bánh giò: It is a dish, which is made from rice flour with pork meat, cloud ear, grains of black pepper, dried onion, salt as filling, wrapped in banana leaves in Pyramid shape and boiled to cook.
  • Bánh bò: It is a sweet, chewy sponge cake, which is made from glutinous rice flour, water, sugar, and yeast. Bánh bò nướng is cooked by baking in a pan in an oven. Bánh bò hấp is steamed and is often smaller in size.

III.2 Some Popular Foods Made from Rice Papers or Bánh tráng

Rice papers are prepared from flour from high amylose content (higher than 27%) milled or broken rice by wet milling. The flour is made into batter of the right consistency, about 42% by weight, for production of flat noodle using a complex machine. In Vietnam, in the absence of the flat noodle making machine, a measure of rice batter is poured onto a flat, shallow measuring ladle onto a taut cheese cloth over a steamer, spread over the whole surface by making a circular motion of the ladle and steamed until gelatinized. The sheet is then removed from the steamer and spread out to a bamboo tray and dried and they are called Bánh tráng in Vietnamese or rice papers. Bánh tráng are eaten dried (khô) or fried (rán), or baked (nướng), or wetted with water (ướt). They are typically served rolled (cuộn) or baked (nướng), in salads, soups and stirred fried Vietnamese dishes. The different dishes of rice wrappers are:

III.3 Foods Made from Flat Rice Noodles

The fresh or dried rice wrapper maybe cut into rice flat noodle strips. Dried flat rice noodles have a glassy, almost transparent appearance and a fragile and brittle texture, but after cooking they do not remain transparent as the cooked glass noodles, which are made from ground mung-bean. Once cooked, flat rice noodles have a milky white color of milled/polished rice. Following are some popular dishes made with flat rice noodles.

  • Phở is a dish of flat rice noodle, which is popular throughout the country, perhaps as popular as cơm. It is also widely appreciated worldwide. Vietnamese eat phở at any time during the day as breakfast, lunch, dinner or snack. Steamed/boiled bánh phở are served in a bowl with a broth and choice meat. The broth of phở bò is generally made by simmering beef bones, oxtails, flank steak, charred onion, charred ginger and spices such as cinnamon, star anise, black cardamom, coriander seed, fennel seed, clove, salt and black pepper seed. The broth of phở gà is made by simmering chicken bones, onion, ginger and spices such as star anise, coriander seed, fennel seed, clove, salt and black pepper. The choice meat of phở bò are slices of beef tenderloin, while that of phở gà are choiced pieces of chiken meat. They or different phở are consumed with ingredients such as green onions, basil, fresh chili pepper, lemon, mung bean sprouts, coriander leaves, and ngo gai or saw tooth herb. Additionally, fish sauce, hoisin sauce and chili sauce may be added to taste as accompaniments.
  • Mì Quảng: It is a popular dish in Quảng Nam Province. It is a dish of steamed/boiled flat rice noodles tinted yellow with turmeric. The broth is made by pork meat and bone, black pepper, shallot and garlic. The proteins are usually shrimp, pork, and chicken. Extras include hard-boiled egg, crushed peanuts, chả or Vietnamese steamed pork sausage, chili pepper or chilli sauce, fresh vegetables including rau húng lủi or water mint, basil, water spinach, ngo gai or saw tooth herb, bắp chuối bào or sliced banana blossom, and lettuce, and pieces of bánh tráng nướng or roasted rice paper. Additionally, fish sauce, hoisin sauce and chili sauce may be added to taste as accompaniments.
  • Hủ tiếu is a popular dish Mekong River Delta. It is a dish of steamed/boiled flat rice noodles. The broth is made from pork bones, dried squid, and sugar, and seasoned with a bit of fish sauce. Meat toppings including different types of meat, such as pork loaf, minced pork, pork belly, duck, seafood or offal. Number of garnishes and aromatic herbs are added in accordance with preferences.

III.4 Foods Made from Extruded Rice Noodles or Vermicelli

Extruded noodles or Vermicelli are prepared from aged, high amylose content (higher than 27%) milled or broken rice by wet milling, kneading into fist size ball, surface gelatinizing of the flour ball in a boiling water bath until they float, remixing, extruding and subjecting extruded noodles in boiling water, taking the noodle out and soak them in cold water and then sun drying. The round rice noodles or rice vermicelli are bún in Vietnamese. Following are some popular dishes made with extruded rice noodles.

  • Bún bì: The steamed/boiled bún are eaten with or long thin strips of pork skin and fried pork mixed with thính or a Vietnamese spice made from roasted rice or grilled rice paper, ground fine.
  • Bún chả giò: The steamed/boiled bún are eaten with spring rolls
  • Bún thịt nướng: The steamed/boiled bún are eaten with grilled pork. It is common dish in Southern Vietnam
  • Bún chạo tôm: The steamed/boiled bún are eaten with chạo tôm or shrimp paste grilled on sugar cane sticks.
  • Bún bò xào: The steamed/boiled bún are eaten with stir-fried beef
  • Bún chả: The steamed/boiled bún are eaten with roasted meat. The dish is popular in the North, especially Ha Noi.
  • Bún bò Huế: It is a popular rice dish from Huế. Steamed/boiled bún are served in a bowl with a broth, slices of marinated and boiled beef shank, chunks of oxtail, and pig’s knuckles. The broth is made from beef bones and beef shank, lemongrass, fermented shrimp sauce and sugar. Sometimes, cubes of congealed pig blood are added to a bowl of bún bò Huế. Commonly served with lime wedges, cilantro sprigs, diced green onions, raw sliced onions, chili sauce, bắp chuối bào or sliced thinly sliced banana blossom, red cabbage, mint, basil, Vietnamese coriander or rau ram, saw tooth herb and sometimes mung bean sprouts. Additionally, fish sauce, hoisin sauce and chili sauce may be added to taste as accompaniments.
  • Bún riêu: It is popular dish in Soc Trang Province. Steamed/boiled bún are served in a bowl with a broth, which is made of either crabs for bún riêu cua), or fish for bún riêu cá) or snails for bún riêu ốc. The dish is served with fried tofu, rice vinegar, Garcinia multiflora Champ., annatto seeds to redden the broth, congealed pig’s blood, split water spinach stems, shredded banana flower, rau kinh giới or Elsholtzia ciliata, spearmint, perilla, and bean sprouts. Additionally, fish sauce, hoisin sauce and chili sauce may be added to taste as accompaniments.
  • Bún thang is a popular dish of Ha Noi. Steamed/boiled bún are served in a bowl with a broth, slices of omelet of duck egg, pieces of chicken meat, shrimps. The broth is made by using the water that resulted from boiling a chicken, roasted pork bones, shrimps, dried squids, onion, salt, sugar, mushroom, and black pepper seed. The dish is served with Vietnamese coriander or rau răm, minced onion leaves, slices of onion. Additionally fish sauce, hoisin sauce and chili sauce may be added to taste as accompaniments.
  • Bánh hỏi: The steamed/boiled bún are woven into intricate bundles and are often topped with chopped scallions and a complementary meat dish. The dish is popular in Bình Định Province.
  • Bánh tằm cà ri: The steamed/boiled bún are eaten with spicy chicken curry. The dish is popular in Cà Mau

IV. OTHER PRODUCTS MADE FROM MILLED RICE

Following are other Vietnamese products made from milled rice.

Cơm rượu: It is a rice pudding in Southern Vietnam. Steamed/boiled milled glutinous rice, is mixed with yeast, rolled into small balls, and fermented. The balls are served in a slightly alcoholic milky, which also contains small amounts of sugar and salt. It is traditionally made and served during Tết Đoan Ngọ on the 5th of fifth Lunar month.

Rượu nếp: It is a rice wine in Northern Vietnam. Steamed/boiled milled glutinous rice is mixed with yeast and fermented into wine. Either deep purplish-red or yellow milled glutinous rice is preferred. It is traditionally made and served during Tết Đoan Ngọ on the 5th of fifth Lunar month.

Rượu cần: It is a rice wine in Central Highland and Northwestern Mountainous Region. Steamed/boiled glutinous rice is mixed with yeast and several kinds of herbs (including leaves and roots) in the local forests. The types and quantity of herbs added differs according to ethnic group and region. This mixture is then put into a large earthenware jug, covered, and allowed to ferment for at least one month. The strength of rượu cần is typically 15 to 25 percent alcohol by volume.

Rượu đế: It is a rice distilled liquor originally from Mekong Delta region. Steamed/boiled milled rice, either glutinous or non-glutinous, is mixed with yeast, fermented, and distilled. It is usually clear in appearance. The strength of rượu đế varies, but it is typically at 40 percent alcohol by volume.

Cốm: It is a dish of immature rice kernels. The immature rice kernels are roasted over very low heat then pounded in a mortar and pestle until flattened. It can be eaten plain or with coconut. It is also used to make a cake, called bánh cốm, and a sweet soup, called chè cốm.

V. UTILIZATION OF OTHER PARTS OF RICE PLANTS

The ratio of grains to straw of modern and improved rice varieties is about 1 or a rice crop that produces 1 ton of rice grains produces also 1 ton of rice straw. The ratio of grains to straw of traditional varieties is less than one. On the average, the milling and pilling of 1 ton of raw rice or paddy grains produce about 650 to 680 kilograms of milled rice grains, 70 to 100 kg of broken rice or tam, about 50 to 70 kg of rice bran (or cam), and about 190 kg of rice husks and hulls. Vietnamese utilized these other products from rice crop to provide additional values in their daily life.

V.1 Utilization of Broken Rice

Majority of farmers used broken rice to feed livestock. Some broken rice is cooked to produce cooked rice called cơm tấm. Before 1975, at Da Kao market in Saigon there was a restaurant that served cơm tấm with a slab of grilled pork chop marinated in sugar and fish sauce or a slice of steamed pork loaf topped with fried egg, and which is a mixture of pork skin and thinly shredded pork. Broken rice is also being used to produce rice flour for processing into other products as mentioned above.

V.2 Utilization of Rice Bran

In the past rice bran was fed to live stocks such as pigs and chicken. After 1980, however, about 50% of the quantity of rice bran produced in Vietnam was used in the production of rice bran oil, which is subsequently used in production of soap and other products. High quality rice bran oils are also used in the production of cosmetics. De-oil bran is mixed with soybean to produce feed for livestock and fish.

V.3 Utilization of Rice Straw

The main parts of rice plants are grains and straws. Vietnamese named the upper parts of rice straw as rơm and the lower part of rice straw as rạ. In the old time, Vietnamese used rice straw in cooking, making roof for house, and feed straw to buffaloes and cattle. Houses in villages in the past usually have a pile of rice straw in their front garden/yard. Rice straw is also used as animal bedding and mixture of straw and animal excretions were used as organic fertilizers in rice production, especially in north and central regions. Some farmers used rice straw to grow mushrooms. With the availability of threshing machines, farmers do the threshing of their rice on the rice fields and afterward they burn the rice straw to facilitate rice crop intensification, but this practice has been discouraged in the recent past.

V.4 Utilization of Rice Husks and Hulls

Great part of rice husks and hulls is used to generate energy for food cooking, for brick fabrication, and for drying rice grains and products of other crops. Rice husk stoves have been produced for use in cooking at home and production of energy in other activities (Phan Hieu Hien et al, 2000). Ask of rice husks and hulls are applied to rice fields and other crops as fertilizers.

REFERENCES

  • Juliano BO and CP Villareal 1993 Grain quality evaluation of world rice. IRRI, Los Banos, Philippines
  • La Van Chu 1990 Rice by-products utilization in Viet Nam. PP 115-117 in Rice by-product utilization in selected countries in Asia. FAO, Bangkok, Thailand 1990
  • Phan Hieu Hien, Nguyen Van Xuan, Nguyen Hung Tam, Le Van Ban va Truong Vinh 2000 May say hat o Viet Nam. Nha xuat ban Nong Nghiep, Ho Chi Minh, 2000