post-harvest technology of rice terminologies

Trang 1

Page | 1

For more Information contact: Visit Rice Knowledge Management Portal http://www.rkmp.co.in

Rice Knowledge Management Portal (RKMP)

Directorate of Rice Research,

Rajendranagar, Hyderabad 500030 Email: naiprkmp@gmail.com , pdrice@drricar.org , shaiknmeera@gmail.com

PO: PAU Campus, Ludhiana-141 004 (Punjab)

Trang 2

Page | 2

Ph: 91-40-24591218, 295 Fax: 91-40-24591217

Rough rice or paddy: Defined as rice in the husk after threshing

Stalk paddy: Defined as unthreshed in the husk, harvested with part of the stalk

Husked rice/brown rice: Rice from which the husk only has been removed retaining still the bran

layers and most of the germs Such rice is sometimes reflected to as bran rice even though there are variations having red or white bran coats

Milled rice: Rice from which husk, germs, bran layers have been substantially removed by lower

machinery, also known as polished rice and if milled to high degree it is called as white rice

Under milled rice: Rice from which the husk germs and bran layers have been partially removed

by power machinery and is also known as unpolished rice

Hand produced rice: Rice from which the husk, germ and bran layers have been partially removed,

without the use of power machinery, also known as “home produced” or “hand milled rice”

Parboiled rice: Rice, which has been specially processed by steaming or soaking in water, heating

usually by steam and drying Parboiled paddy can be milled to various degrees or home produced

in the same way as ordinary paddy It is called as parboiled milled or parboiled hand pounded

Raw milled: The paddy, which is milled not after giving heat treatment, such as parboiling

Coated rice: Defined as rice milled to a high degree and then coated with glucose on “Talcum” Whole grain: Refers to husked, milled or hand produced rice which does not contain any broken

grains smaller than 3/4 of the size of the whole kernel

Broken rice: Husked, milled or hand produced rice consisting of broken grains of less than 3/4th

size of the whole grain but not less than 1/4th

Fragmented rice: Small brokens upto 1/4th size of the whole grain

Husk: The by-product from the milling of rice consisting of the outermost covering of the rice

kernels

Bran: A by-product from the milling of rice consisting of the outer layer of the kernels with part of

germ

Rice polishing: Now defined as the by-product from milling rice, consisting of the inner bran layer

of the kernel with part of the germ and a small percentage of the stoney interior also known as rice meal or rice flour elsewhere

Trang 3

Page | 3

Ph: 91-40-24591218, 295 Fax: 91-40-24591217

Glutinous rice: A type of rice, which after cooking has a peculiar stickyness regardless of how it is

cooked

Scented rice: A type of rice, which contains aroma and gives scented smell on cooking

Rice flour: Ground polished rice which is mainly starch with very little gluten Used in the same

way as corn flour and for noodles, sweets and short pastry

Quick cooking rice: Rice that had been completely cooked then dehydrated

Head rice yield: Head rice yield is the weight percentage of rough rice that remains as whole rice

(three-fourths kernel or greater) after complete milling

Milling yield/Total yield: Milling yield is the weight percentage of rough rice that remains as

milled rice; i.e., the sum of head rice and "brokens."

Rice bran oil: It is the oil extracted from the germ and bran of rice

Puffed rice: It is a type of puffed grain made from rice; usually made by heating rice kernels under

high pressure in the presence of steam, though the method of manufacture varies widely

Popped rice: Raw rice is traditionally popped by heating rough rice at higher temperatures about

240°C for up to 45 seconds The hull contributes to pressure retention before popping aGood popping varieties have a tight hull and a significant clearance between hull and brown rice and when freshly harvested are free of grain fissures

Rice flakes: The production of rice flakes begins with parboiling of rice which helps to soften the

grain and prepare it for processing Once the rice is tender, the cooked grains are rolled and flattened After the mixture is the desired thickness, the flattened rice is allowed to dry completely The dried flakes are run through another rolling process to create simple flakes

Trang 4

Page | 4

Ph: 91-40-24591218, 295 Fax: 91-40-24591217

Introduction

Rice is the staple food for 65% of the population in India It is the largest consumed calorie source among the food grains With a per capita availability of 73.8 kg it meets 31% of the total calorie requirement of the population India is the second largest producer of rice in the world next to China In India paddy occupies the first place both in area and production Indian Basmati Rice has been a favorite among international rice buyers Following liberalization of international trade after World Trade Agreement, Indian rice will become highly competitive and has been identified as one of the major commodities for export This provides us with ample opportunity for development of rice based value-added products for earning more foreign exchange Apart from rice milling, processing of rice bran for oil extraction is also an important agro processing activity for value addition, income and employment generation

It has been reported that about 9 percent of paddy is lost due to use of old and outdated methods of drying and milling, improper and unscientific methods of storage, transport and handling It has been estimated that total post harvest losses of paddy at producers’ level was about 2.71 percent of total production To minimise post harvest losses, precautions should be taken to follow proper post harvest practises They include timely harvest at optimum moisture percentage (20 percent to 22 percent), use of proper method of harvesting; avoid excessive drying, fast drying and rewetting of grains Ensure drying of wet grain after harvest, preferably within 24 hours to avoid heat accumulation, uniform drying to avoid hot and wet spots and mechanical damage due to handling The losses in threshing and winnowing can be avoided using better mechanical methods Proper sanitation during drying, milling and after milling to avoid contamination of grains and protect from insects, rodents and birds and use of proper technique

of processing i.e cleaning, parboiling and milling helps in reduction in post harvest losses To avoid storage losses maintaining optimum moisture content i.e 12 percent for longer period and 14 percent for shorter storage period is essential

Harvesting at proper maturity

Paddy crop should be harvested, when the grains become hard and contain about 20-22 percent moisture Harvesting before maturity means a low milling recovery and also a higher

Trang 5

Page | 5

Ph: 91-40-24591218, 295 Fax: 91-40-24591217

proportion of immature seeds, high percentage of broken rice, poor grain quality and more chances of disease attack during storage of grain Delay in harvesting results in grain shattering and cracking of rice in the husk and expose the crop to insects, rodents, birds and pests attack, as well as lodging Harvesting during wet weather conditions should be avoided and done by adopting proper method The water from paddy field should be drained about a week or 10 days before the expected harvesting, which helps in employing mechanical harvesters Avoid pest infestation prior to harvesting Harvested material should be protected from rain and excessive dew by covering, avoid direct sun drying, which leads to an increase in breakage of the grains during milling For combine harvesting, moisture percentage should be 18 per cent, or lower When paddy is harvested by hand it gets a chance to get dried before threshing In the case of combine harvesting, a sizeable percentage of green kernels are threshed along with mature kernels It paddy is harvested with a combine harvester and kept in gunny bags, rotting of seed will invariably start Therefore, it is very necessary that the paddy harvested with combine harvesters must be dried until moisture percentage comes down to 13 per cent, or lower Similarly, the paddy harvested by hand should also be dried to 13 per cent or below moisture content At the time of storing the moisture in the seed grain should never exceed 13 per cent and there should

be no green kernels Use tarpaulin or pukka (cemented) floor for drying

Threshing of Paddy

Align all the panicles in one line to get proper threshing If the threshing is delayed, keep the harvested paddy stalk bundles in a dry and shady place, which facilitates the air circulation and prevents excessive heating Thresh the paddy in the field itself Transport the grain in bags, which minimises the grain losses Avoid too much post harvest handling of paddy to minimise the grain losses Pack the paddy in sound B-Twill jute bags totally free from any contamination

Simple pedal operated threshers are also used to thresh the paddy in the field One person operates the thresher with foot pedal and one or two persons feed the bales from behind for threshing These threshers are also motorised with Single phase 1HP electric motor for threshing

of Paddy The machine is run and one or two persons feed the bales from behind for threshing

Trang 6

Page | 6

Ph: 91-40-24591218, 295 Fax: 91-40-24591217

Mechanical Paddy threshers consist of worm type threshing cylinder, oscillating box, winnowing and cleaning attachment, feeding chute etc These threshers can be operated both with motor and diesel engine tractors During threshing the paddy crop's straw is separated from grain by worm type cylinder The straw is thrown out from the machine with the help of blower Other impurities like dust/dirt are thrown out through other outlet Extra blowers provided cleaning the grains of left-over impurities The capacity of these machines varies from 300 kg/h to

1500 kg/h

Cleaning of Paddy

The hand operated and power operated winnowing fans are commercially available The paddy threshed by manual beating or by pedal operated paddy thresher is cleaned by using these fans These winnowing fans consist of frame either made up of wood, angle iron, welded steel or combination of the two along with driving mechanisms namely, sprocket and chain, belt and pulleys and single or double reduction gears

A hand operated paddy winnower was developed by Central Rice Research Institute, Cuttack Two women workers are required for the operation of this winnower, one for cranking the blower and other for feeding the threshed material and collection of grain The average output was found to be 242 kg grain/h and winnowing efficiency was found to be 88.36% The equipment developed was found to be suitable for operation by women workers as the heart rate, work pulse value and energy expenditure rate are within the acceptable limits

Motorised paddy winnowing machine was developed at TNAU Coimbtore It consists of a feed hopper to hold the grain for cleaning It discharges the grain over a scalper and removes bigger size impurities A blower provided at the bottom, passes air against the grain falling through the scalper which separates the straw, chaff and other impurities The dust, chaff and straw are collected separately and cleaned paddy is taken out through another outlet near the bottom of the unit The capacity of the machine is 500-750 kg/h and operated with 1 hp motor The cost of machine is Rs 20,000 and cost of cleaning comes to Rs 5/100 kg

Trang 7

Page | 7

Ph: 91-40-24591218, 295 Fax: 91-40-24591217

Milling of Paddy

Rice milling is the oldest and the largest agro processing industry of the country At present

it has a turn over of more than 25,500/- crore per annum It processes about 85 million tonnes of paddy per year and provides staple food grain and other valuable products required by over 60%

of the population Paddy grain is milled either in raw condition or after par-boiling, mostly by single hullers of which over 82,000 are registered in the country Apart from it there are also a large number of unregistered single hulling units in the country A good number (60 %) of these are also linked with par-boiling units and sun -drying yards Most of the tiny hullers of about 250-

300 kg/hr capacities are employed for custom milling of paddy Apart from it double hulling units number over 2,600 units, under runner disc shellers cum cone polishers numbering 5,000 units and rubber roll shellers cum friction polishers numbering over 10,000 units are also present in the country Further over the years there has been a steady growth of modern rice mills in the country

Basic Milling machines

Traditional huller

It is a relatively small unit with a throughout capacity of 100 to 150 kg per hour operated

by oil or steam engine or an electric motor In small villages single hullers are used while in bigger mills of 1 to 2 tonnes per hour capacity batteries of 3 to 4 hullers are used Most of the other operations, excepting milling proper, are done invariably The huller does the job of the husk removal and bran removal simultaneously The working element of this machine is made of cast iron, which bears very heavily on rice grains thereby breaking them to pieces which are liable to be lost alongwith husk The hullers even though cheaper in cost are wastage and have high labour requirement

Centrifugal shellers

In this machine the grains are subjected to centrifugal force by means of a rotating impeller Significant characteristics of these centrifugal shellers are: Their high capacity and simple constitutional features as there is only one moving part i.e an impeller Its casing is lined with

Trang 8

Page | 8

Disc sheller

In this type the two operations of dehusking and whitening were intended to be carried out separately in separate machines The disc sheller mills may be called unit mills as all the operations involved in milling, cleaning, dehusking paddy separation, polishing and grinding are done mechanically and by separate machines The basic machine i.e under runner disc sheller consists of two discs with their inner faces lined with emery bottom one rotating and the other stationary The paddy passes in between the two discs and gets shelled or dehusked Therefore the breaking is less and the white rice yield is also more of the order of 66-68 percent with 10 to

15 percent brokens There are adjustments provided on the dehusker so that the clearance between the discs could be adjusted for most of the variety of paddy It gives a marked increase (2

to 4 percent) in rice output over conventional huller in almost all milling condition

Rubber Roll Sheller

The greatest advantage of rubber roller over cast iron cylinder or the emery roller is that due to their compressible nature the grain handled gently during the process of dehulling The functional coefficient between paddy grain surface and rubber is lower than that of paddy and steel This facilities easy dehulling The two rubber rollers rotate in opposite direction at differential speed to take off the aspiration Since all the paddy is not dehusked paddy must be separated This is accomplished by a paddy separator The brown rice (rice with bran coating on) is then fed to rice whitener where the bran is removed.The rubber roller mill gives better quality rice and bran which fetch more price in the market

Trang 9

Page | 9

Ph: 91-40-24591218, 295 Fax: 91-40-24591217

Composite Rice Mill

The basic rice milling processes consists of Pre Cleaning to remove all impurities and unfilled grains from paddy, De-stoning for Separating small stones from paddy, Husking to removing husk from paddy, Aspiration to separate the husk from brown rice/ unhusked paddy, Paddy Separation which separates the unhusked paddy from brown rice, Whitening to removing all or part of the bran layer and germ from brown rice, Polishing to improve the appearance of milled rice by removing the remaining bran particles and by polishing the exterior of the milled kernel, Length Grading to separate small and large brokens from head rice, Blending is for mixing head rice with predetermined amount of brokens, as required by the customer

The recovery of whole grains in a traditional rice mill using steel hullers for dehusking is around 52-54% There is excessive loss in the form of coarse and fine brokens Further loss of large portion of endosperm layers during the dehusking operation further accentuates the problem Against it, the recovery percent of whole grains in modern rice mills using rubber roll shellers for dehusking operation is around 62-64% The whole grain recovery percent further increases to 66-68% in case of milling of parboiled paddy Thus it can be seen that there is an overall improvement

of recovery of whole grains by about 10-14% if one uses rubber roll shellers for rice milling operations The recovery of various components from these improved rice mills are milled head rice: 62-68%, rice bran: 4-5%, rice husk: 25%, and germ wastages: 2%-8%

It has been observed that dehusking using rubber roll shellers reduces the risk of breaking the grain because husk is pulled off almost at once and pressure is applied by means of resilient surfaces across the width of the grain, where kernels, generally are much more uniform than they are by length Moreover, the process does not remove the internal epidermis of the husk Thus the deshelled grains with their silver skin envelope are protected against scratches and keep longer and better while the silver skin and the germ increases the quantity of bran which is produced while whitening The improved rice mills have a better husk and rice bran aspiration system The same prevents mixing of fine brokens with rice bran Therefore the quality of rice bran obtained is better

Generally 2.00 to 2.50 acre of land is required for establishing an improved rice milling unit having an installed processing capacity of 2 MT/ hr; operating for single shift / day of 8 hr

Trang 10

Page | 10

1 Raw paddy godown- RCC framed superstructure with 10'' thick brick walls, IPS flooring with damp proof treatment with 1.62 kg DPC /sq.m of floor area and base of the side walls, roofing consisting of ACC sheets affixed with J hooks, bolts and other accessories to steel truss made of

MS angle of desired section 80' x 35'

2 Cleaning Shed - Similar to the raw paddy godown 25' x 32'

3 Milling shed -RCC framed superstructure with brick walls, IPS flooring and roofing consisting of ACC sheets affixed with J Hooks and nuts to steel trusses made of MS angle of desired section and strength bearing capacity 80' x 35'

4 Finished product or Milled rice storage shed 30' x 35'

5 Machine shed - with masonry structure with ACC sheet roofing on lean truss 40' x25'

6 Auxiliary structures; a Office unit 10' x 15' , Labor quarters 30 ' x 15', Machine Room for auxiliary machines like blowers/ generator set etc 40' x 15', Bore well and water connections, e Sanitary and plumbing

Trang 11

Page | 11

Ph: 91-40-24591218, 295 Fax: 91-40-24591217

Parboiling of Paddy

Parboiling of paddy is a hydrothermal process in which the starch granules within the rice grain are gelatinized by the application of steam and hot water This helps in higher percentage of recovery of head rice Parboiling rice drives nutrients, especially thiamine, from the bran into the grain, so that parboiled white rice is 80% nutritionally similar to brown rice It reduces breakage in milling, improves storage life and helps in the preservation of protein and vitamins in the rice The starches in parboiled rice become gelatinized, making it harder and glassier than other rice In conventional methods, parboiling is carried out by hot water soaking and subsequent steaming Under the prevailing global energy crisis, any parboiling method which saves energy is a welcome feature Energy can be saved in the parboiling process by skipping any one of the three distinct unit operations namely, soaking, steaming and drying or by combining any two operations at a time Direct steaming of freshly harvested high moisture paddy improves the head rice recovery but with inferior quality Parboiling of the soaked paddy could be carried out with less energy input by applying the dry heat instead of moist heat (steam) which takes care of both gelatinization and subsequent drying One of the possible methods for energy saving for parboiling

of paddy is the continuous dry-heat parboiling The dry-heat parboiling has the unique feature of parboiling and drying of paddy, simultaneously The heat requirement for parboiling of paddy is the same irrespective of method employed to achieve it, however the efficiency of the system is governed by thermal efficiency of the heating source, heat transfer between source and the subject, heat loss by conduction, convection and radiation, and sensible heat of the system

Drying of parboiled paddy

Sundrying of parboiled paddy

Most of paddy parboiled in the traditional mills is sun dried on a drying floor The drying floor is normally cemented floor consisting of layer of brick bats with cement plaster on it The parboiled paddy is spread on the floor 10 to 30 mm thick layer by labour with the help of a plank then it is continuously stirred by a spiked plank or by feet After four hours of drying in sun, paddy

is heaped and covered by mats for tempering for a period of 2 to 3 hours Then the paddy is spread again for 2 hours in the sun to dry it to desirable moisture content Therefore, drying of

Trang 12

Page | 12

Ph: 91-40-24591218, 295 Fax: 91-40-24591217

parboiled paddy from 30 percent to 13 percent moisture content takes about 6 hours during summer and relatively long period about 8 to 10 hours during winter

Mechanical drying of paddy

It is the process utilising mechanical means for drying grain by ventilating natural air or heated air through the grains mass to accomplish removal of moisture from it In other words mechanical drying of paddy refers to removal of moisture from wet paddy by unheated and/or heated forced air at a predetermined rate of flow, air temperature and air relative humidity Rate

of moisture removal could be regulated It is observed that if paddy is harvested at about 24 percent moisture and dried mechanically in stages by 3 or 4 passes of heated air the milling losses are minimum Heated air convection type dryers are commonly used for drying paddy Types of commonly used dryers are Bag dryers, Bin or batch dryers, Continuous flow dryers and Rotary drum dryers

Bag Dryers:

This type of dryer is suitable for drying smaller quantity of grains It requires large number

of unskilled labour for handling the bags The dryer consists of a large floor area in the building with the opening over which the grain bags are placed The openings are covered with a perforated material to support the bags and allow air movement through the bags The air is blown in the holes by a burner and air blower assembly In this type dryer, air is heated up to 45°C and is blown in the dryer at the rate of 4 cubic meters per minute per bag of 45 kg of dried grains The bag should be turned once during operation for exposing both sides to heated air

Batch Dryer:

The dryer consists of a bin or a container to hold grain with an air blower and a burner for providing hot air The bin or the container is fitted with a perforated bottom in case of most of the bin or batch dryers However godown or a room in a building with a perforated floor may also be used The godown or room is equipped with air dust system for air distribution throughout the room A fan with heater unit is then connected to the duct system to supply the required air to dry the grains In all batch type dryers the depth of grain is limited due to high power requirement to force air through deeper grain mass

Trang 13

Page | 13

Ph: 91-40-24591218, 295 Fax: 91-40-24591217

Continuous flow dryers:

Continuous flow dryers are of two types (I) mixing and (ii) non-mixing type Both types of dryers are used for commercial drying of paddy and hence high drying capacities Grain is usually fed in the top and flows through the dryer by gravity Rate of discharge is mechanically regulated

at the bottom Drying is accomplished by forcing heated air through the grain as it flows downwards In non-mixing columnar dryer the paddy descends between two parallel screens set

15 to 20 cms apart while heated air is blown through the screens No appreciable mixing occurs and effect is similar to drying in static bed with a depth equal to distance between the screens Mixing type are of many designs, two of the most popular being baffle design and Louisiana State University design In a baffle dryer paddy flows downward in zig-zag path through the baffles while heated air is forced through the grains The Louisiana State University dryer consists of a bin in which layers of inverted shape air channels are installed Alternating layers are air inlet and air exhaust channels Each layer is offset so that the top of each inverted channel split in the stream

of paddy coming on it Paddy flows between channels taking a zig-zag path as it descends Drying air passes from air inlet the air exhaust channels thus removing moisture from the paddy

Rotating Drum dryer:

This consists of a large drum 1 to 2 meter in diameter and 3 to 6 meters in length placed on

a slight inclination and the drum rotates about its axis The inside of the drum is equipped with the helical straight edge ribs to provide the mixing and the forward movement of the paddy during drying operation The hot air blown at the lower end of the drum and the paddy flows counter current to direction of air flow These types of dryers are normally used for drying parboiled paddy

Modern Paddy Dryers

The new developed mechanical dryers reduced the moisture of parboiled paddy from 12% in a continuous operation within a few minutes This offers several advantages over the conventional dryer in terms of lower utility consumption, reduction in breakage, no color variation, single pass drying, increase in equipment life and minimal maintenance It is supplied with steam heater, hot air blower and exhaust fan with dust collection system The continuous steaming and drying system consists of Continuous steaming vessel with feed and discharge

Trang 14

Page | 14

to 22% This paddy at 22% moisture is fed into second fluid bed dryer where the moisture is reduced to 16% and is then fed into third fluid bed dryer where the moisture is further reduced to 12-14% However, in case of Basmati Rice, the moisture is reduced to 22% using the static and first Vibro Fluid Bed Dryer and further drying is carried out in LSU dryer upto 12%

Mini Parboiling Unit

Improved parboiling technique of hot water soaking and atmospheric steaming (CFTRI) and pressure parboiling (RPEC) has been developed The Cuttack centre has developed a mini parboiling unit for on farm/domestic parboiling of paddy Traditionally soaking and steaming are done separately with parboiling unit Both the operations can be done without any further handling in the same unit A hot soaking for 3-5 hours in 75°C water and steaming and subsequent sun drying results in about 2 percent more head rice than achieved traditionally The capacity is 75

kg per batch with output of 150 kg per day

Toxins in Rice

Aflatoxin: -Aflatoxins are the type of mycotoxins, which are derived from the fungi, which affect human health Aflatoxins are produced by Aspergillus flavus, Aspergillus ochraceus and Aspergillus parasiticus Contamination of Aflatoxins occurs at any stage from field to storage, whenever environmental conditions are conducive for fungi The fungie are generally regarded as storage fungi, which grow under conditions of relatively high moisture/humidity It causes severe liver damage and both liver and intestinal cancer in humans Generally, milled rice contains low

Trang 15

Page | 15

Ph: 91-40-24591218, 295 Fax: 91-40-24591217

levels of Aflatoxins, but parboiled rice and paddy harvested in rainy season contains high Aflatoxin levels Storage insects like rice weevil, lesser grain borer, khapra beetle, etc also encourage Aflatoxins in paddy/rice According to PFA Rules, 1955, the Aflatoxins in rice should not be more than 30 microgram / kilogram

Prevention and Control of Aflatoxins: The paddy/rice should the stored at safe moisture level Prevent the growth of fungi by drying of grains Use proper and scientific storage method Prevent insect infestation by adopting chemical treatment to avoid fungus contamination Separate the infected grains

Packaging

Good packaging provides not only convenient handling in transportation and storage but also attracts consumers to pay more Packaging is essential to avoid spoilage and to prolong the quality Packaging of paddy/rice is also important for long-term storage to fulfil the demand of old rice in the market, particularly in case of Basmati and non-parboiled rice Paddy/rice, if kept in open, quality may be adversely affected Packaging is closely related to labelling and branding In present scenario, branding and labelling of rice has significant impact on consumer preference More care is required in packaging of rice meant for export This is because of demonstrative effect and the requirements of consumers in different countries; exporters have now started using transparent, colourful and attractive packaging For good packaging, the packages must protect rice very well and should be long lasting, look clean, convenient to handle and carry out from the store easily

The graded rice should be packed in new, clean, sound and dry jute bags, cloth bags, polywoven bags, polyethylene, polypropylene, high molecular high density polyethylene paper packages or in other food grade plastic/packaging materials The packages shall be free from insect infestation, fungus contamination, deleterious substances and undesirable or obnoxious smell Each package shall be securely closed and suitably sealed The rice shall be packed in quantities as specified under the provisions of the Standards of Weights and Measures (Packaged Commodities) Rules, 1977 as amended from time to time Suitable number of consumer packs

Trang 16

Page | 16

Ph: 91-40-24591218, 295 Fax: 91-40-24591217

containing graded material of the same lot may be packed in master container The packaging materials used in packaging of paddy/rice are Jute bags, HDPE / PP bags, Polythene impregnated jute bags, Poly pouches and Cloth bags Usually, the cost of a HDPE bags may be around 50-60 percent of the cost of jute bags In paddy/rice, usually B-Twill jute bags are used The initial cost of packaging varies according to the type of material used for making bags Rice is stored in HDPE bags for six months, whereas in jute bags, for 3 months Thus, the economics of packaging depends not only on the type of packaging material but also the duration for which the paddy/rice

is likely to be stored

Transportation

Paddy is transported usually in bulk from field to the market, while rice is transported both

in bulk and bags The following means of transportation are used at different stages of marketing There are different modes of transport used in paddy/rice transportation Road and rail transport are normally used for internal markets, whereas, for export markets, the mode of transport is by Sea

Road transport is the most predominant mode of transport used in the movement of paddy/rice Road transport is used in right from the producing fields to the ultimate consumer The initial movement of paddy/rice is done on village roads, which are generally non tarred (Kachha), and mostly tracks wind through the fields Over the years, road transport has expanded phenomenally, due to the development of roads in rural areas, as well as by the increase of numbers and efficiency of different types of vehicles i.e trucks and tractors etc The following means of road transport are employed in different parts of the country to transport paddy/rice

Railway is one of the most important means of transportation of paddy/rice Railway is cheaper than road transport and more suLa transport of paddy/rice depends on distance, quantity etc Railway transportation requires more handling cost, as it requires loading and unloading charges and local transportation cost However, losses are more in case of transport by railways

For safe and scientific storage of paddy/rice, the storage should be easily accessible The land of the site should be protected from moisture, excessive heat, insects, rodents, and bad

Trang 17

Page | 17

Ph: 91-40-24591218, 295 Fax: 91-40-24591217

weather conditions In godowns, sufficient space should be provided between two stacks for proper aeration The structure should be clean, free from left-over grains, cracks, holes and crevices in the structure and should be fumigated before storage Before storage, paddy/rice grains should be properly dried and cleaned to avoid quality deterioration It is advisable to always use new and dry gunny bags If old bags are to be used disinfect them by boiling in 1 percent Malathion solution for 3-4 Minutes and dry them properly Separate storage of should be maintained for new and old stock Bags of should be kept on wooden crates or bamboo mats along with a cover of polythene sheet to avoid absorption of moisture from the floor Proper aeration should be provided in clean weather condition and avoided in rainly aseason

Improved storage structures

1 Improved bins

Different organisations developed and designed improved storage structures for scientific storage of foodgrains, which are moisture resistant and rodent-proof These are Pusa Kothi, Nanda bins, PKV bins, PAU bins, Hapur Kothi and Chittore stone bins etc

2 Brick-build godowns

These are made by brick-walls with cemented flooring for storing paddy/rice in bulk and bags

3 Cement plastered bamboo bin

This bin developed by Post Harvest Technology Centre, Kharagpur, in which bamboo strips are used to form the skeleton of the bin and cement-sand mortar (1:2.5 ratio) is plastered on outer and inner surface of the bin

4 CAP (Cover and plinth) storage

It is an economical way of storage on a large scale The plinth is made by cement concrete and bags are staked on open and covered by polythene cover

5 Silos

Silos are used for storage of foodgrains These are made from concrete, bricks and metallic materials with loading and unloading equipment

Utilisation Pattern

Trang 18

Page | 18

Ph: 91-40-24591218, 295 Fax: 91-40-24591217

Staple food: Rice is a staple food and used by many ways as under Rice is used as a staple food by

more than 60 percent of World population Cooking of rice is a most popular way of eating There are many ways of domestic use like khichadi, pulav, kheer, zeerarice, iddli, dosa etc

Starch: Rice starch is used in making ice-cream, custard powder, puddings, gel, distillation of

potable alcohol, etc

Rice bran: It is used in confectionery products like bread, snacks, cookies and biscuits The

defatted bran is also used as cattle feed, organic fertilizer (compost), medicinal purpose and in wax making

Rice bran oil: Rice bran oil is used as edible oil, in soap and fatty acids manufacturing It is also

used in cosmetics, synthetic fibers, plasticisers, detergents and emulsifiers At present, about 6 lakhs tonnes of rice bran oil is produced from 35 lakhs tonnes rice bran per annum in the country

It is nutritionally superior and provides better protection to heart,

Flaked rice: It is made from parboiled rice and used in many preparations

Puffed rice: It is made from paddy and used as whole for eating

Parched rice: It is made from parboiled rice and is easily digestible In India, about 4-5 percent of

total supplies of rice is used as parched rice

Rice husk: It is used as a fuel, in board and paper manufacturing, packing and building materials

and as an insulator It is also used for compost making and chemical derivatives

Rice broken: It is used for making food item like breakfast cereals, baby foods, rice flour, noodles,

rice cakes, Idli and dosa etc and also used as poultry feed

Rice straw: Mainly used as animal feed, fuel, mushroom bed, for mulching in horticultural crops

and in preparation of paper and compost

Paddy as a seed: The paddy is used as seed The proportion utilized for seed purpose varies from 2

to 6 percent of total production

Trang 19

Page | 19

Ph: 91-40-24591218, 295 Fax: 91-40-24591217

Innovation in Rice Processing

Soft drying for high moisture paddy

Soft drying of paddy is a quite new concept in which moisture transfer takes place from raw paddy to dry dusk utilizing dry husk’s hygroscopic character without heat stress under normal temperature (Fig 1) The running cost of soft drying is low because no heat is required, only aeration is done using high capacity blowers The storage tanks with mixing arrangements can be used for drying The process provides higher head yield due to no heat stress to grain as in sun drying or mechanical drying There is no cracking of grain due to drying It is energy saving technique because of no heavy mixing of paddy during drying The drying of moistened paddy is relatively simple as there is no quality concern In the process, dry husks are likely to absorb moisture from raw paddy moisture Gradually, moisture contents of higher and lower get balanced

Bio polishing

Mechanical milling results in lower head rice yield with loss of major nutrients To minimize the loss incurred during mechanical milling and to resolve the problems associated with brown rice, a novel alternative polishing method has been attempted to bio-polish the rice with some selected multi-enzymes having the catalytic properties to degrade the bran layer of rice The enzymes are the selective biocatalysts, which are very specific to their targeted reactants Thus through such processes the amount of by-product yield is minimum These enzymes can be produced in large quantities through biotechnological route where different types of bioreactors can be used Depending upon the nature of fermentation process, the reactor systems can be selected

Such bio-polishing has been carried out on germinated brown rice to get softer, nutritious brown rice with the added benefits of germinated rice The bio-polished rice has been found to be superior in every aspect when compared to milled rice The salient features of bio-polishing are no loss in head rice yield, nutrient rich than milled rice, fibre content more than milled rice, with benefits of germinated brown rice, softer with less cooking time than brown rice, enzyme treated

Tiêu đề	Post-Harvest Technology of Rice Rice Terminologies
Tác giả	Dr. R.T Patil
Trường học	Central Institute of Post Harvest Engineering and Technology
Chuyên ngành	Post Harvest Technology
Thể loại	Bài viết
Thành phố	Ludhiana

Định dạng
Số trang	38
Dung lượng	5,59 MB