Rice; uses, cultivation, processing, storage, nutrients and products

Rice, whose botanical name is Oryza sativa is an edible starchy cereal grain and the grass plant from the family Poaceae by which it is produced. Roughly one-half of the world population, including virtually all of East and Southeast Asia, is wholly dependent upon rice as a staple food; 95 percent of the world’s rice crop is eaten by humans. Rice is cooked by boiling, or it can be ground into flour. It is eaten alone and in a great variety of soups, side dishes, and main dishes in Asian, Middle Eastern, and many other cuisines. Other products in which it is used are breakfast cereals, noodles, and such alcoholic beverages as Japanese sake. It is the seed of the monocot plants.

Rice is the seed of the grass species Oryza sativa (Asian rice) or less commonly Oryza glaberrima (African rice). The name wild rice is usually used for species of the genera Zizania and Porteresia, both wild and domesticated, although the term may also be used for primitive or uncultivated varieties of Oryza.

PHYSICAL DESCRIPTION

The cultivated rice plant is an annual grass and grows to about 1.2 metres (4 feet) in height. The leaves are long and flattened and are borne on hollow stems. The fibrous root system is often broad and spreading. The panicle, or inflorescence (flower cluster), is made up of spikelets bearing flowers that produce the fruit, or grain. Varieties differ greatly in the length, shape, and weight of the panicle and the overall productivity of a given plant.

PROCESSES OF RICE PRODUCTION

There series of steps in the production of rice from the initial stage of plant to the final stage of packaging or consumption. These steps as;

Field Preparation & Planting

February – Early May

Rice is cultivated differently than other grains because it is a semi-aquatic plant that requires consistent irrigation all season to grow. Heavy clay and silt loam soils that are often ill-suited to other crops retain water very well, making them perfect for rice.

Prior to planting, farmers prepare the land using precision GPS and laser-guided earthmoving equipment to create uniform grades and slopes within fields, which decrease water use and increase productivity.

Planting begins in late February through May depending on the production region. Farmers use modern technology to plant the seed, either by airplane or grain drill.

Irrigation & Growing

March – Early August

Rice plants grow to a height of three to four feet over an average of 120 days after planting. During this time, farmers irrigate the rice fields using the method that best fits that field or farm. The traditional irrigation method is to construct earthen levees that follow the contour of the land and flood the field with about two to four inches of water which is maintained over the growing season. Flooded fields prevent soil erosion, lead to improved water quality, as well as other environmental benefits like habitat creation.

Farmers can also irrigate their fields with poly-tubing, using precisely punched holes that allow them to apply water more evenly and efficiently across the field. There are even irrigation methods that allow a farmer to grow rice in rows like other crops and apply water periodically during the growing season instead of maintaining a layer of water. Farmers continue to innovate ways to save water and time by using irrigation practices that fit their unique operations.

By mid to late summer, the rice plant begins to show signs of maturation with the grain appearing in long panicles on the top of the plant.

Harvest

Mid-July – November

When rice is mature, water is drained from the fields and sophisticated combines cut the rice and separate the grain from the stalks. Harvested grains are taken to drying facilities where they utilize forced warm air to gradually reduce the moisture content to a level best suited to storage before the it moves to the milling process.

Milling and polishing

Milling is a mechanized process where the harvested “rough rice” passes through sheller machines to remove the inedible hulls. This process yields brown rice with the bran layers surrounding the kernel still intact. Brown rice can be used as is or further milled by machines that rub the grains together under pressure. This abrasion removes the bran layer to produce white or “polished” whole kernels of rice. Finally, the white rice is enriched with a thin coating of vitamins to replace some of the nutrients lost during milling.

Storage

The purpose of any grain storage facility is to provide safe storage conditions for the grain in order to prevent grain loss caused by adverse weather, moisture, rodents, birds, insects and micro-organisms like fungi.

In general, it is recommended that rice for food purposes be stored in paddy form rather than milled rice as the husk provides some protection against insects and helps prevent quality deterioration.

However, when rice can be stored as brown rice, 20% less storage capacity will be needed. Brown rice is rice grain with its hulls removed but not polished. Under tropical conditions brown rice has a very short shelf life, approximately two weeks.

Rice storage facilities take many forms depending on the quantity of grain to be stored, the purpose of storage, and the location of the store. Storage systems can be through bag, bulk, or hermetic containers.

Bag storage;

In most parts of Asia grain is stored in 40−80 kg bags made from either jute or woven plastic. Depending on the size of storage, these bags are normally formed into a stack.

When using bag storage consideration needs to be given to the following:

Jute bags should not be stacked higher than 4 m and plastic bags 3 m. Plastic bags are more slippery and the stacks will be less stable.
Bags should be stacked under cover e.g. under a roof, in a shed or granary or under water proof tarpaulins.
A one meter gap should be left between and around stacks and 1.5 m clearance between the top of the stack and the roof.
Bags should be stacked on pallets or on an above ground structure to avoid the possibility of absorbing moisture from the floor.
Bags should not be stacked on a bed of rice husks or bags filled with rice husks, as these are difficult to keep free from insect infestation.
Bags should be stacked so that fumigation can be undertaken easily. The dimensions of the stacks should be set to facilitate sealing with a single fumigation sheet.
The efficiency of bag storage can be improved if a hermetic plastic liner bag like the IRRI Super bag is used inside the existing storage bag especially for seeds but also for commercial rice.

Some farmers use bag storage in outside granaries, which have been constructed from timber or mud/cement or large woven bamboo or palm leaves.

Bulk storage of Rice;

At farm level grain is often stored in bulk in small outside granaries or in woven baskets or containers made from wood, metal or concrete, which are located under or inside the house. These storages vary in capacity from 200−1000 kg .Losses from insects, rodents, birds and moisture uptake are usually high in traditional bulk storage systems.

Commercial bulk storage of rice;

The large export mills and collection houses sometimes use metal or concrete silos. These silos range in size from 20−2,000 ton capacity. Silos have the advantage that they can be more easily sealed for fumigation and less grain is spilt or wasted. Silos are not very common in Asia because of problems with moisture migration inside the silo which results in hot-spots and molds.

Hermetic storage

In hermetically sealed storage systems grains are placed inside an airtight container, which stops oxygen and water movement between the outside atmosphere and the stored grain.

NUTRIENTS IN RICE

Rice provides 20% of the world’s dietary energy supply, while wheat supplies 19% and maize (corn) 5%. Cooked non enriched long-grain white rice is composed of 68% water, 28% carbohydrates, 3% protein, and 1% fat (table). A 100-gram (3+¹⁄₂-ounce) reference serving of it provides 540 kilojoules (130 kilocalories) of food energy and contains no micronutrients in significant amounts, with all less than 10% of the Daily Value (DV) (table). Cooked short-grain white rice provides the same food energy and contains moderate amounts of B vitamins, iron, and manganese (10–17% DV) per 100-gram serving (table).

A detailed analysis of nutrient content of rice suggests that the nutrition value of rice varies based on a number of factors. It depends on the strain of rice, such as white, brown, red, and black (or purple) varieties having different prevalence across world regions. It also depends on nutrient quality of the soil rice is grown in, whether and how the rice is polished or processed, the manner it is enriched, and how it is prepared before consumption.

RICE PRODUCTS

Varieties of products can be made from rice, ranging from different indigenous dishes, feeds for farm animals, soil nutrients to different ways of serving rice and other rice products.

Masa, agidi, ogi etc are an indigenous food made from rice, rice oil, flour, husk used as animal feed, rice bran and straw are all rice products.