Difference between revisions of "Rice (incl. transport guidelines)"
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Most of rice moving in world trade is fully milled and bagged. Packaging requirements in contracts may be anywhere from a shipload full of bulk (loose) rice to 1 kg retail boxes, but 50 kg (or 100 lb) bags being common sizes. | Most of rice moving in world trade is fully milled and bagged. Packaging requirements in contracts may be anywhere from a shipload full of bulk (loose) rice to 1 kg retail boxes, but 50 kg (or 100 lb) bags being common sizes. | ||
The international rice trade is under a quarter of that in wheat, which trades almost 20% of tits world production. However, in value terms the rice trade is closer to wheat – approximately one quarter – about half of the sugar trade and almost as much as the cocoa trade. | The international rice trade is under a quarter of that in wheat, which trades almost 20% of tits world production. However, in value terms the rice trade is closer to wheat – approximately one quarter – about half of the sugar trade and almost as much as the cocoa trade. | ||
| + | ==<H6>1.5 Definition of 'rice'</H6>== | ||
Revision as of 08:11, 13 July 2012
| Infobox on Rice (incl. transport guidelines) | |
|---|---|
| Example of Rice (incl. transport guidelines) |  |
| Facts | |
| Origin | This table shows only a selection of the most important countries of origin and should not be thought of as exhaustive.
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| Stowage factor (in m3/t) |
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| Angle of repose | - |
| Humidity / moisture |
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| Oil content | - |
| Ventilation | Loading as bulk cargo: surface ventilation. Loading as general cargo: air exchange rate 15 - 25 changes/hour. Good surface ventilation and airing are necessary. |
| Risk factors | At an excessively high water content in particular, rice has a tendency towards self-heating. Water contents of > 15% and relative humidities of > 75% result in self-heating of the cargo due to hydrolytic/enzymatic fat cleavage. Rice is highly odor-sensitive, prone to contamination and shrinkage. Beware of infestation. |
Rice (incl. transport guidelines)
Contents
Transport guidance on bagged rice
As a cereal grain, rice is the most important staple food for a large part of the world's human population, especially in Asia and the West Indies. It is the grain with the second-highest worldwide production, after maize (corn).
Since a large portion of maize crops are grown for purposes other than human consumption, rice is the most important grain with regard to human nutrition and caloric intake, providing more than one fifth of the calories consumed worldwide by the human species.
Therefore we have extended the article on rice to a transport guidance, in order to prevent loss as much as possible.
Introduction
1.1 Types of rice cargoes
Rice, or Oryza, can vary in height from 1 – 6 m. It is an extremely adaptable plant; it has an efficient system of air passages connecting the roots and the shoot. This enables it to grow in dry upland soils, in irrigated fields, or along flooded river beds, Rice is largely self-pollinated, but cross-pollination does occur in degrees ranging between 1 – 30%.
There are over 85.000 varieties of rice in the research stocks of the International Rice Research Institute (IRRI), and there are over 120.000 cultivars known to exist. The familiar distinctions to Westerners of long grain versus short grain, or white versus brown, are but two. Like wheat, oats or maize, rice is a cereal. It is a basic diet for over 50% of the world’s population and is therefore the most important crop in the world. The range of varieties is so great that no internationally recognised system of classification exists, although repeated efforts have been made since the Rice Congress at Valencia in 1914 urged ‘the formation of a real botanical classification of the varieties of cultivated rice’. Two species are cultivated, Oryza sativa and Oryza glaberrima (wild rice – in West Africa).
Asian rice, Oryza sativa, is divided into two categories, both of which include glutinous and non-glutinous varieties. Indica rices’ grains are longer and more slender, and they usually remain separate when cooked. Japonicas have shorter, rounder and more translucent grains which quickly become slightly sticky. Indica grains are divided into medium (5 – 6 mm) or long grain (more than 6 mm). It was proposed in 1958 to coin another name, javanica, for the bulu and gundil varieties of Indonesia. Most rices grown in the tropical zones belong to the indica and javanica groups, which tend to have a fixed growth period. Japonia rices have shorter grains (4 – 5 mm) and are also different in terms of taste and smell. They are highly sensitive to photoperiod, or day length, and so do poorly in the short-day tropics. They are, however, widely grown in N. China, Korea and Japan. Then there is glutinous rice, (Oryza sativa L. glutinosa) which is specified as having a starch level of 99$ amylopectine. The grains are completely opaque, and this rice tends to be reserved by Asian populations for confectionery and cakes.
The long grain varieties, Oryza indica, tend to be preferred by the people of Inda and SE Asia; the Japanese and Indonesians prefer the stickier, short grained variety Oryza japonica.
Rice plants are usually grown in flooded fields known as paddies, although there are varieties which can be grown ‘dry’, for example in Tanzania, Zambia and the Philippines – these tend to produce a lower yield, however. The roots of the rice plants are kept underwater. The head of the plant, known as the panicle, contains small spikelets which produce grains of raw rice, known as paddy.
Before the paddy field is flooded, the soil needs to be broken up and levelled. In most rice-growing countries, the seeds are first sown in nurseries. Small corners of the paddies are set aside for sowing. On the first night, the seeds are often kept in water, to allow germination, then planted. About 30 days later, the rice plants are pressed into the mud in rows. The rice plants are often under attack from weeds or pests such as rats, worms, birds and snails – hence there are often fish in the paddy fields. Fish are no protection, however, against the other threats of hurricane, drought or rats.
Rice matures very quickly in the right growing conditions. The life cycle of the rice plant is generally 100 – 210 days; the average falls between 110 – 115 days. In temperate climates the average duration from sowing to harvest is about 130 – 150 days. Cultivars with growth duration of 150 – 210 days are usually photoperiod sensitive and are planted in the deepwater areas. Temperature and day length are the two environmental factors affecting the development of the rice plant, which can be divided into three phases:
- Vegetative – from seed germination to panicle initiation;
- Reproductive – from panicle initiation to anthesis;
- Ripening – from anthesis to full maturity.
Controlled irrigation dramatically improves yields – most rice needs between 250 – 600 grams of water for each grain of rice eventually formed. When ready for harvesting, rice is a golden yellow.
Combine harvesters can cut the rice, separate the grain from the straw, and leave the straw in the field.
When harvested, rice typically contains from 15 – 22% (US) or 19 – 25% (Asian) moisture and therefore must be dried to a moisture content of 12 – 14% to prevent spoilage. The rice dries in the sun, or it can be dried by blowing hot air through piled sacks of grain, which reduces the risk of disaster from sudden torrential rain. Paddy is then stored to protect it from damp, heat, rodents, insects, birds and fungi; it can be stored in large pots or bamboo baskets, or in lofts or barns on stilts. Rice can be stored for years. Modern steel or concrete silos automatically control the humidity and temperature of the vast amounts of paddy which they contain.
After being dried and stored, the rice goes through the milling process, which removes the tough outer husk and inner layers of bran from the edible rice grain. Unfortunately, milling also removes much of the goodness, hence the gradually increasing demand for brown rice. However, most consumers like white rice, so the grain is also polished white, and sometimes also glazed with glucose and talc. From 100 kg of paddy (rough rice), 20 kg of husk and 80 kg of brown, de-husked rice can be obtained. From the milling process, 68 kg of milled rice (or parboiled rice, where the rough rice is exposed to steam pressure and the grain becomes harder and less sticky) and 12 kg of bran and other by-products are obtained. From the 68 kg, 55 kg can be expected to be wholegrain and 13 kg broken grain.
Rice is traded either as paddy or milled rice and an indication is needed in the description of the product i.e. paddy/brown/milled/parboiled. Other mentions needed are grain type (long or short), origin and the percentage of broken rice, for instance, Thai white rice long grain 5% broken.
Electronic sorting machines can classify the size, type and colour of each batch of rice and separate the different grades for packaging. The main patterns of good quality are:
- Colour – as white as possible (no discolouration, no imperfections);
- Whole grains – minimum percentage or broken grain.
Standards in most countries define the percentage of brokens and other imperfections allowed in each grade of rice, and the basis on which such percentages are measured.
1.2 Composition and nutritional value
The composition and nutritional value of rice varies with the nature of the soil, climate, variety, the conditions of culture – in particular the fertilizers used, etc; this it has in common with all vegetables and grains. But for rice in particular, the nutritional value depends on the degree of milling that is undertaken. Brown rice contains 8% protein, 70% starch and small quantities of lipids, fibre and minerals. After milling, however, the decline in beneficial elements is dramatic, see Table 1.1. This shows a dismal picture indeed when one considers the social, economic and, above all, taste pressure which encourages the milling of rice. The reasons for the dramatic fall in nutritional value after milling are as follows:
The starch is found principally in the endosperm; the lipids, fibres, vitamins and minerals are concentrated in the cellulose layer. Glucose molecules are found in two forms; amylase and amylopectine, the proportion varying between varieties. Most current varieties contain 12 – 35% amylase, the rest being amylopectine. Glutinous rice is low in amylase and tends to stick together in cooking. Simple sugars such as sucrose are present in brown rice in the 0,6 – 1,4% range, and in white rice from 0,3 – 0,5%. Fibre is present in the shell of brown rice but hardly at all anywhere else and therefore only marginally in white rice. Proteins, the second major constituent of rice, are present in the endosperm in the form of 1 - 3µm granules but these are eliminated in the milling process. Of 17.600 varieties of rice analysed by the IRRI, the percentage of protein varied from 4,3 to 18,2% with a middle point of 9,5%. Table 1.2 shows the amino acid content of the different forms and elements of IR-8.
Table 1.1 - Effect of refining and parboiling on rice, 100 g.
| Energy, Kcal | |||
| Protein, g | |||
| Lipids, g | |||
| Fibre, g | |||
| Cendres, g | |||
| Thiamine, mg | |||
| Riboflavin, mg | |||
| Niacine, mg |
Table 1.2 - Amino acid content of the different forms and elements of IR-8 - g/16,8 gN
| Amino acid | |||||
| Isoleucine | |||||
| Leucine | |||||
| Lysine | |||||
| Met + Cys | |||||
| Phe + Tyr | |||||
| Threonine | |||||
| Tryptophane | |||||
| Valine | |||||
| Chemical score | |||||
| Proteins | |||||
| Proportions by weight | |||||
| Distribution of proteins | |||||
| Tryptophane |
A 100% = 3,76 g Met + Cys/16,8 gN
B 100% = 5,78 g Lys/16,8 gN
Source: IRRI
Brown rice has 1,8 – 3,9% lipids, concentrated in the aleuron and embryo. Most is in the bran; polished rice contains only 0,3 – 0,7% lipids. These are used industrially (a.o. rice oil for animals and soap products).The mineral value of rice is another factor which is adversely affected by milling, see Table 1.3.
Table 1.3 - Mineral value of rice, mg/kg
| Calcium | ||
| Phosphate | ||
| Iron | ||
| Sodium | ||
| Potassium | ||
| Zinc |
Source: IRRI
There is not much iron, and half is in the part removed by milling. The ratio between calcium and phosphate is not ideal; the phosphate is found mainly in the form of phytates.
The level of vitamins A and D is negligible, although there is a great deal of vitamin E. There is little riboflavin (0,6 mg/kg in brown rice), and virtually no vitamin C, but there is ample thiamine (3,4 mg/kg of brown rice) and niacine (52 mg/kg of brown rice) as well as pyridoxine and panthotenic acid. An average serving (6 oz) of cooked rice gives enough energy to walk for 45 minutes, because it contains 345 kcal per 100 kg, which is almost identical to wheat and maize (340 and 342 respectively). This is for 100 g of dry rice, of course, and after cooking rice triples its volume. 100 g of cooked rice contains 120 cal, 3 g of proteins, 0,1 g of lipids, 0,01 mg of thiamine and 3,4 g of niacin. Bran and ‘polish’ together contain about 85% of the oil, 10% of the protein, 80% of the thiamine (B1), 70% of the minerals and fibre, 50% of the riboflavin (B2) and 65% of the niacin of the whole grain. White rice is 90-94% pure starch and when highly polished contains only 7% protein by comparison to 10% for brown rice. Based on 100 g portions, the caloric content of cooked rice is 111 for brown rice, 109 for regular milled and 106 for parboiled. Rice is a complex carbohydrate, supplying energy over long periods. Another important function of a dietary carbohydrate is energy sparing – the body does not use protein to meet energy needs when a carbohydrate is available. The protein content of rice is of good quality because it contains all the amino acids necessary for human life; it contains only a trace of fat and is cholesterol free; it is non-allergenic and gluten-free, and is very low in sodium. Rice starch is almost completely digested, and between 65 – 88% of rice proteins are digested, depending on how adult the person is – children do not absorb rice proteins as effectively. A number of studies have been carried out on the optimum addition of proteins to a predominantly rice-based diet, and in general it appears to depend on the type of rice being consumed so that general indications are hard to draw.
As a food, it contains all the carbohydrate that individuals need in their diet, being 90% carbohydrate itself/ Dry rice produces 3,5 kilocalories per gram, compared with 8 kcal for a gram of fat. Rice is a good source of various B group vitamins such as thiamine (B1) which helps control various body functions, the human nervous system, and also contributes to healthy skin. B group vitamins are water-soluble and cannot be stored in the body; therefore a regular intake is essential. Natural brown rice is an excellent source of dietary fibre which performs many vital functions within the human body; it eases the disposal of waste products and is also easily and quickly digested, making it especially suitable for athletes, babies and the elderly.
Most specialist doctors believe that the fibre in foods like brown rice plays an important role in prevention of diseases such as diabetes, heart disease and cancer of the colon. In the past, fibre was thought to add bulk to food but to have little other benefit. Now it is widely recognised that it is a far more complicated substance and is not digested by human beings. The indigestible fibre passing through the bowel can reduce the amount of fat absorbed by the body from fatty foods. It can also help slow down the rise in blood glucose after a meal, particularly beneficial to people within diabetes who need to control their blood sugar levels. Brown rice however, takes up to 40 minutes to cook, compared to less than ten for milled white rice, which is inconvenient for many people.
Rice does, however, provide insufficient protein on its own for a healthy diet. Moreover, the loss of real food value caused by the milling process makes it little short of a world tragedy that the preferred consumption of rice is in its milled, white, highly polished form, when it is easier to eat and quicker to cook. Malnutrition, especially in infants, causing protein deficiency, beri-beri, iron and zinc deficiency, is common in countries where rice forms an overwhelming percentage of the population’s diet. Beri-beri has increased since the increase in use of mills, and was common in Thailand in the 1970s. It is only the increased income of the country in general that has led to alternative foods being available in that country since then, which has cut the problem dramatically. Adding riboflavin to rice causes discolouration, which has dissuaded Far Eastern eaters. There is clearly a need to increase the supplementary elements to a rice-based diet, for example meat, milk, eggs and above all fish, and vegetable oils; to increase the amount of parboiling, and of brown rice to be eaten.
Malnutrition problems are actually exacerbated by the introduction of efficient mechanised units due to the more efficient milling. One way of avoiding the loss of nutrients during milling is first to parboil the raw paddy rice. Parboiling involves transferring the proteins and vitamins from the bran layers to the white central part of the seed, by steeping the paddy in hot water, steaming it and drying it before milling. This procedure gelatinises the starch in the grain, and ensures a separateness of grain. Parboiled rice is favoured by consumers and chefs who want a fluffy, separate cooked rice. It retains more nutrients than regular-milled white rice, but takes a few more minutes to cook.
It is possible to restore valuable nutrients after milling by adding solutions of thiamine, niacin, iron and riboflavin. Enriched rice has greatly helped to improve the problem of malnutrition in many rice-eating countries. Rice is a very palatable cereal; the only one which can simply be boiled and eaten without degenerating into mush.
1.3 Food and animal feed uses
Rice is used almost exclusively for human consumption; hardly any is used as animal feed. In all Asian countries, China, India and Bangladesh in the East and Japan and Korea in the South, rice is the most eaten cereal by far. Average annual consumption is about 100 kg per person with a wide variation between countries. In Vietnam it reached 240 kg per person in the 1980s. In Laos and Thailand 202 kg, in Bangladesh 160 kg, whereas in the Philippines it was 89 kg, in India 73 kg and in China estimates vary from 72 – 96 kg/person. The variations are accounted for by the use of other cereals. These levels compare with 4 kg annually per person in France, for example.
The types of rice in which each market is interested vary enormously, which is a factor of great significance for the international rice trade itself. Sadly, much of this trade involves shipping rice to countries that already grow it because the national tastes do not suit the particular type grown.
Two very good examples of this practice are the export of round grain rice from Italy and the import of long grain rice; and the import of fragrant Thai rice into California. In both cases, domestic rice production is slowly changing to meet the changes in demand, but it must be realised that the types of rice demanded can vary so much that one form of rice can be completely unacceptable to one market. For example, the Japanese market, at least for the time being, prefers white short grain rice, recently milled, of a japonica variety. The Thais, by contrast, prefer a well-milled rice, stored for some time, of a long grain indica easily separable variety.
Again, Middle Eastern consumers prefer long grain rice with a strong taste, whilst Europeans prefer tasteless long grain rice. Africans prefer broken rice, especially of the red tinted type. Bangladeshis prefer parboiled rice which is easily cooked. One regrettable but abiding fact is that brown rice is little appreciated in tropical countries. In hot countries brown rice keeps badly, but the real reason is that brown rice symbolises poverty in these countries, people try to avoid it, and it is considered inappropriate to serve it to guests.
Unlike other cereals, rice is usually presented to the consumer in its raw form, so it is according to visual criteria that rice is judged – the length of the grain, the degree of whiteness, the translucence, the proportion of broken grains and so on. The EC distinguishes four types of rice on the basis of the ratio of the length to the breadth of the grain, see Table 1.4.
Table 1.4 - Grain types
| Round grain | ||
| Middle grain | ||
| Long grain A | ||
| Long grain B |
Source: ONIC
The cooking qualities of rice are largely determined by the relative quantities of amylase and amylopectine in the starch and to a lesser extent by the level of proteins and the temperature of gelatinisation. The more amylase, the better the rice stays apart when cooked. Less than 20% between 20 – 25% and 25 – 36% are the three classes in this matter. Indica rice consumers in India, Pakistan, Bangladesh, Malaysia and South China prefer varieties high in amylase, i.e. a ‘dry’ rice after cooking, whereas in the Philippines and Indonesia, intermediate levels of amylase are preferred, and the Japanese and North Chinese choose ‘sticky’ rice. In North Thailand and Laos, glutinous rice is preferred. Parboiling, practised largely in India, Bangladesh and Sri Lanka, produces a further set of distinguishing characteristics largely appreciated in those countries only. It is however, worth adding that in western countries a growing appreciation of all types of rice is now occurring, and even Thai fragrant rice can now be bought in the average British supermarket – an extraordinary change from the 1970s when only long grain US rice was available, apart from short grain rice contained in deserts.
Rice is now eaten in almost every country in the world. For example, it is used in Spanish paella, the popular US dish of jambalaya and with curry in virtually every Asian country and the U.K. Rice is also eaten toasted or coated with sugar or chocolate as a breakfast cereal. Rice can be eaten on its own, or coloured with saffron or turmeric, or flavoured with herbs and spices. For example, pilau rice is made by adding peppers, stock and onion. Rice is also used to make powerful alcoholic drinks, for example, saki (Japan) and wang-tsai (China) come from rice. Almost one-third of the rice used in the USA goes to make beer.
Rice must be cooked before the human body can absorb the starch. There are basically four ways in which rice is cooked: with just enough water, by boiling in a large quantity of water and draining, cooking in fat (as with paella, risotto and pilaff) and steaming. The temperature necessary for cooking rice depends on the starch and protein composition of rice: ordinary white rice takes about 16 minutes to cook (less in a microwave oven). Rice increases in size from 100 kg to 230 – 240 kg after cooking. This capacity for retaining water actually poses a problem for infant nutrition: the infant stomach can retain only 180 ml at 2 years, so to get 1000 kcal of energy, it would be necessary for the infant to ingest about 1 kg. However, it is possible to reduce this absorption by introducing other cereals into the cooking. To reduce the time taken in cooking, pre-cooked rice has been put on sale, which has reduced cooking time to only a few minutes.
Ground rice flour is used to thicken sweets and sauces, and to replace wheat flour in the diet of people who suffer from food allergies. Wheat flour loaves are often dusted with rice flour before baking, and powdered rice is used in some developing countries to make noodles, cakes and sweetmeats. Rice paper is also used to cook cakes and sweets such as macaroons; rice bran is used for animal feed. The stubble from rice is ploughed back. The straw is used for making hats, shoes, ropes, mats and for thatching. The surplus straw is used as animal fodder and bedding. Rice husks, removed by milling, have little nutritional value but they are very rough and contain silicon, which is useful as an industrial abrasive. The husks are used as fuel in village stoves, as insulation, for making lightweight brocks and as a packing material. New uses are constantly being researched for the 75 m tonnes of husks produced every year. Rice is also used for starch production, glucose, rice vinegar and rice oil.
By contrast, the bran has a very high nutritional content. It can be refined to make a fine, clear oil, low in fatty acids, which is good for cooking and for protecting industrial machinery from rust. Broken rice is bought by brewers, who use it to make liquors such as saki and arrak. Whole and broken rice is used for making starch. Tinned pet foods and sausage fillings often contain a percentage of broken rice. It is evident, then, that rice has a variety of nutritional, feed and other uses, vital to the lives of billions of rice consumers across the world. It is important to realise how essential rice is.
1.4 Rice qualities traded
Paddy: usually with a guaranteed milling yield such as 55 – 68 meaning that out of 100 kg of paddy the miller will obtain after milling 55 kg of white grains and 13 kg of broken grains, giving a total yield of 68 kg. Only a few countries, notably the USA, export their paddy rice.
Brown (dehusked): usually required by the rice industry with a guaranteed yield, e.g. US 2/4/73 – 73% whole grain, 12% bran and 15% brokens.
Some commercial rice mills are in the rice producing countries such as Indonesia; others are in the rice consuming countries, including Britain and Holland which import raw paddy for their mills.
Of milled rice, the most widely traded qualities are:
White:
- US milled No. 2/4 long grain (grade 2/4% brokens) to Europe/Middle East/Latin America
- US milled 5/20 LG (grade 5/20% brokens) in US foods aids
- Thai White Rice 100%B (4,5% broken maximum) to Middle East (Iran/Iraq), Malaysia
- TWR 5/10/15/25/35% brokens
- Broken 100% either for human consumption or as animal feed
Parboiled:
- Thai parboiled 5% brokens to Benin/Nigeria/Bangladesh
Most of rice moving in world trade is fully milled and bagged. Packaging requirements in contracts may be anywhere from a shipload full of bulk (loose) rice to 1 kg retail boxes, but 50 kg (or 100 lb) bags being common sizes. The international rice trade is under a quarter of that in wheat, which trades almost 20% of tits world production. However, in value terms the rice trade is closer to wheat – approximately one quarter – about half of the sugar trade and almost as much as the cocoa trade.