Code and Title of the Paper: F01FS Food Science Code and Title of the Module: F01FS17 Parboiling of Rice Name of the Content writer: Dr. M. Amirthaveni Quadrant - I 1. Introduction Rice is the staple diet for more than half of the world’s population. It is consumed principally in Asia. Rice forms up to 80 percent of the food intake in some countries. It is cooked in boiling water and eaten mostly with cooked pulses, vegetables, fish or meat. In India, several types of dishes are prepared from rice flavored with spices and other ingredients. Other rice preparations include parched rice, puffed rice, flaked rice and fermented preparations like ‘idly’ and ‘dosa’. Byproducts of rice, such as bran, rice polishing and paddy straw are used for feeding livestock Parboiled rice (also called converted rice) is rice that has been partially boiled in the husk. The three basic steps of parboiling are soaking, steaming and drying. These steps also make rice easier to process by hand, boost its nutritional profile and change its texture. About 50% of the world’s paddy production is parboiled. The treatment is practiced in many parts of the world such as India, Bangladesh, Pakistan, Myanmar, Malaysia, Nepal, Sri Lanka, Guinea, South Africa, Italy, Spain, Nigeria, Thailand, Switzerland, USA and France. Rice is easier to polish by hand (removal of the bran layer) after parboiling but mechanical processing is harder since the bran becomes somewhat oily and tends to clog machinery. Most parboiled rice is milled in the same way as white rice. Parboiling drives nutrients, especially thiamin, from the bran to the endosperm,[3] hence parboiled white rice is 80% nutritionally similar to brown rice.[citation needed] Because of this, parboiling was adopted by North American rice growers in the early 20th century. Parboiling is a hydrothermal treatment followed by drying before milling for the production of milled parboiled grain. Parboiling of paddy has been known in the orient for centuries. Nearly 50 per cent of the paddy produced in India at present is parboiled.In general, the three major steps in parboiling, i.e. soaking, steaming and drying and have a great influence on the final characteristics and quality of parboiled rice. Parboiling is the latest premilling treatment which improves the quality of rice. The traditional parboiling process in India is carried out in different ways. Code and Title of the Paper: F01FS Food Science Code and Title of the Module: F01FS17 Parboiling of Rice Name of the Content writer: Dr. M. Amirthaveni Today, unpolished rice is becoming popular because of the nutrient value in bran. Therefore, demands for brown rice and parboiled rice are increasing because of their reputation for nutritional excellence and health claims associated with eating these types of rice. However, brown rice has some disadvantages such as lower absorption of liquid into the kernel because the bran in brown rice contains fiber, which leads to prolonged cooking time. Furthermore, the oil content in the bran shortens its shelf life, as the bran becomes rancid. Therefore, parboiling is one alternative to reduce these problems. Parboiling was adopted by North American rice growers in the early 20th century. The process of parboiling itself, however, is more than two thousand years old and believed to have originated in the Persian Gulf. Thailand is a leading rice exporter, especially of parboiled rice. Parboiled rice is actively produced in Thailand for export mainly to South Africa, Nigeria and various countries in Asia, Europe, the Mediterranean and the Middle East. Parboiling improve rice quality and thus fetch higher product price. Aromatic rice (Koa Dok Mali 105) variety having low amylose content is not used in parboiling because of its softness after cooking and higher price. However, some consumers prefer to eat low amylose content rice but do not like the stickiness of the cooked rice. Parboiling process can improve the hardness of the low amylose rice. High amylose content rice requires longer processing time for parboiling, and thus consumes more energy. Hence using low amylose content rice may lead to a reduction in energy costs, decreased grain yellowness, cooking time, gain in texture, smell and preference to consumers. Generally, parboiled rice produced from rough rice leads to increased yellowness, undesirable smell during soaking and retarded heat transfer to the kernel because siliceous husk does not wet easily and resists water movement into the kernel. 2. Objectives: The primary objective of parboiling is to improve the quality of rice and obtain higher milling yield. To exhibit the advantages of parboiled rice over unparboiled product such as strengthening of kernel integrity, preventing the loss of nutrients during milling and improving the shelf life thus preventing the proliferation of fungus and insects. Code and Title of the Paper: F01FS Food Science Code and Title of the Module: F01FS17 Parboiling of Rice Name of the Content writer: Dr. M. Amirthaveni To illustrate the processing techniques, uses and health benefits of parboiled rice. 3. COMPOSITION The chemical composition of rice is influenced to some extent by genetic and environmental factors. The composition of Indian rice is; moisture, 10.9-13.8; proteins, 5.5-9.3; carbohydrates, 73.4-80.8; fiber, 0.2-1.0 and mineral matter, 0.8-2.0 per cent. The germ, the pericarp and the aleuronic layers are richer in nutrients like protein, minerals and vitamins than endosperm that is separated from the grain during milling along with the husk. The major carbohydrate of rice is starch (72-75 per cent). Rice also contains some free sugars like glucose, sucrose and dextrin. The protein content of rice is lower than that of wheat. The rice proteins are richer in arginine compared to other cereal proteins and are deficient in lysine and threonine. Most of the minerals present in rice are located in the pericarp and germ. Polished rice is poor in calcium and iron. 4. NUTRITIVE VALUE OF RICE Beta Ribo- Energy Protein Fat CHO Calcium Iron Thiamine Niacin Food Carotene flavin Kcal g g g mg mg mg mg mcg mg Rice, parboiled, 349 8.5 0.6 77.4 10.0 2.8 9.0 0.27 0.12 4.0 hand pounded Rice, parboiled, 346 6.4 0.4 79.0 9.0 1.0 - 0.21 0.05 3.8 milled Rice, raw, hand 346 7.5 1.0 76.7 10.0 3.2 2.0 0.21 0.16 3.9 pounded Rice, raw, milled 345 6.8 0.5 78.2 10.0 0.7 0 0.06 0.06 1.9 Code and Title of the Paper: F01FS Food Science Code and Title of the Module: F01FS17 Parboiling of Rice Name of the Content writer: Dr. M. Amirthaveni Parboiled rice might sound like it's precooked, but it's not. Instead, it's processed quite differently from other types of rice. The resulting grain is cooked and served just as for white or brown rice. However, because of the special processing, parboiled rice is a better source of fiber, calcium, potassium and vitamin B6 than regular white rice. After rice is harvested, its inedible hull is removed to produce brown rice. If rice is put through a second step of processing to remove the bran, it becomes white rice. Unlike brown and white rice, the process for parboiled rice begins before the hull is removed. The complete grain of rice is soaked, steamed and dried and then the hull is removed to make parboiled rice. The steaming enables the rice to absorb nutrients and changes the starch so that it cooks into a firmer, less sticky dish of rice than regular white rice. The steaming does not precook the rice, so it still takes about 20 minutes to prepare. 4.1 Carbohydrates A cup of cooked parboiled rice provides 41 grams of total carbohydrates, or about one- third of the recommended daily intake of 130 grams. The same portion has 1.4 grams of fiber, which supplies 4 per cent of men’s and 6 per cent of women’s daily fiber. Parboiled rice has double the fiber than you'd get from cooked white rice. It has a low glycemic score of 38, compared with a high 89 for white rice, A low glycemic score indicates that the carbohydrates in parboiled rice do not cause a large spike in blood sugar 4.2 B Vitamins Parboiled rice is especially rich in niacin, providing 4 milligrams or 23 percent of the recommended daily intake in 1 cup of cooked rice. You’ll also get 19 per cent of the daily intake of vitamin B6. These values are about double the amount you would get from non-enriched white rice. Your body needs B vitamins to metabolize food into energy, but they also fill other roles, such as helping make hormones and neurotransmitters. Vitamin B6 removes the amino acid homocysteine from your bloodstream by turning it into other substances. This might help keep your heart healthy; Code and Title of the Paper: F01FS Food Science Code and Title of the Module: F01FS17 Parboiling of Rice Name of the Content writer: Dr. M. Amirthaveni high levels of homocysteine are associated with an increased risk of cardiovascular disease. 4.3 Minerals One cup of cooked parboiled rice supplies 2 to 3 percent of the recommended daily intake of calcium, iron, magnesium and potassium. You'll get a slightly bigger boost of zinc, with 1 cup containing 0.58 milligrams of zinc which represents 5 per cent of men’s and 7 per cent of women’s daily needs. Zinc performs vital roles throughout your body, from forming the structure of proteins to regulating DNA.