Types of Plantation Crops

Types of Plantation Crops

E. CASHEWNUT
Cashewnut (Anacardium occidentale L.) is a tropical evergreen fruit tree belonging to Anacardiaceae family. It is widely cultivated in tropics for its nut and is a native of Brazil. In India it was introduced in Goa from where its cultivation spreaded to other parts of country. Cashew is a versatile tree nut and its kernel contains fats, proteins, carbohydrates, minerals and vitamins. Cashew has become number one crop in the world over almond. India provides around 55% supply of cashew kernels in world. The important commercial products of this crop are nuts and apple. The cashew kernels are used in confectionary and deserts. Cashew apple is eaten fresh or mixed in salads and even a drink is prepared from its juice. Cashew can be distilled to produce alcoholic drink called as Fenny. The cashew shell contains oil known as cashew nut shell liquid (CNSL) which has wide industrial uses. In India, the cashew processing is done manually, which consists of moisture conditioning, roasting, shelling, kernel drying, peeling, grading and packing.

Processing of cashewnut
I. Processing at orchard level
The cashew processing in the orchard is mainly confined to removal of raw nuts from cashew apple and drying. The fully matured nuts are harvested and the apples are removed. The nuts are dried for 2-3 days to reduce moisture from 25% to below 9%. Drying helps the kernels to retain their quality particularly flavour.

II. Processing of raw nuts
The nuts used for processing are dried again to reduce moisture level to 7-8%. The steps involved in processing of raw nuts are as under:
1. Cleaning and grading of nuts: The nuts are cleaned and graded into three sizes, viz, small, medium and large. The grading of nuts is done on basis of nut thickness and not on the basis of its length. It helps in reducing the kernel breakage.
2. Roasting of nuts: Roasting of raw nuts is done to separate the adhering shell from kernel. There are three types of roasting viz; drum roasting, oil bath roasting and steam roasting.

a) Drum roasting: This is one of the oldest and more widely used methods. The nuts are fed into red hot rotating drum which will ignite the shell by maintaining its temperature because of burning of shell liquid. The drum is kept in rotation for 3-4 minutes and roasted nuts are discharged from lower end of drum and immediately covered by ash after sprayed with a little water, to absorb oil on surface. This facilitates removal of remaining oil on shell.

b) Oil bath roasting: The conditioned nuts are passed through CNSL (cashew nut shell liquid) bath heated to 170-200oC by conveyer buckets for 1-2 minutes. During this period the shells gets heated thus rupturing the wall and releasing oil into bath. The roasted nuts are then centrifuged to remove adhering oil, cooled and shelled by hand or leg operated shelling machines. The kernel with adhering testa is scooped out using a sharp needle. The method is followed traditionally in Kerala and Karnataka

c) Steam roasting (autoclaving): The raw nuts are steam cooked at about 120-140 psi pressure to loosen the kernels from shells. Shell oil can be extracted in later stages by crushing. The nuts are shelled by hand or leg operated shelling machines. The steamed nuts are spread on floor under natural air for 12-24 hrs for cooling.
3. Shelling of nuts (decortications): Cashew nut after roasting and cooling are shelled to remove kernels. Care should be taken to protect hands from Cashew Nut Shell Liquid (CNSL) which is highly corrosive. Hand gloves can be used while shelling. Nuts are knocked 2-3 times on long edge of wooden mallet or light hammer to release the whole kernels without any damage. Foot operated shell cutter can be used for shelling. This device consists of a pair of blade (knives) shaped in counter of half a nut. The blade cut through the shell all around the nut, leaving the kernel untouched. A hand lever is pressed to open shell into two parts. The kernel is then scooped out manually.

4. Separation of kernels: After shelling, the kernel and shell pieces are separated manually and the separated kernels are collected into containers.

5. Pre-grading: Pre-grading can be done before and after drying kernels. It can be done mechanically for large scale processing, whole kernels are separated from the broken. Sometimes the whole kernels are also separated and graded according to the kernel size.

6. Drying of kernels: After removal from the shell, the kernels are dried at about 70-800C imperforated trays for about 6-8 hrs for reducing the moisture level to 4-5 percent. Drying of these kernels is necessary to prevent fungus. In order to ensure uniform drying, the position of tray may be changed frequently. Excessive drying may result in scorched kernel. After drying kernels are kept in the moist chamber for 24 hours which facilitates easy removal of testa and minimizes broken kernels.

7. Peeling: it is done by using a sharp knife or bamboo piece to remove testa (seed coat) from the kernels

8. Grading of kernels: Kernels are graded according to the size manually. 25 different grades of cashewnut kernels are approved by Government of India. Standard specification for Indian cashew kernels are:
  • Wholes: White wholes(WW)/scorched wholes(SW)/ dessert wholes (SWS)
  • Broken : White broken/scorched broken/dessert broken
  • Lower grades: Rejection etc.
Further, the classification refers to broken kernels, splits, pieces, small pieces and whether kernels are white or scorched. The cashew kernels are sold as WW 180, WW210, WW240, WW450 and WW500 which means white whole with number of kernel per pound weight. Thus WW210 means white whole with 210 kernels/ lb weight. Similarly scorched wholes are numbered as SW180-SW500. Dessert wholes (DW), white pieces as B (Butts), S (Splits), LWP (Large white pieces), SWP (Small white pieces), BB (Baby bits), Scorched pieces as SB (Scorched butts), SS (Scorched splits), Dessert pieces as SPS (Scorched pieces seconds), DP (Dessert pieces).

9. Packaging of kernels: The import trade requires packaging of kernels in 11.34 kg capacity (25 lbs) tins/airtight cans in which the kernels are kept. After filling and weighing, the tins are evacuated and filled with CO2 with help of vita pack process. This consists of removing all air from can and substituting it with CO2 and the holes in the cans are then sealed. Cashew should be packed in impermeable packages, as they become rancid and go stale quickly.

III. By-Products from cashew
1. Cashew apple: Cashew apple is a swollen peduncle to which nut is attached. It is very juicy and sweet, it is not eaten raw because of its astringent and acidic taste. It is very rich in vitamin C and can be used for juice extraction.

2. Cashew juice: The juice can be extracted with screw press, basket press or hand press. Straining of extracted juice is done through muslin cloth which is then clarified by adding 1.4g of PVP (Poly vinyl pyrolidine) per litre juice; the mixture is stirred and again strains through muslin cloth. Add sugar to improve the taste, and boil the juice. Fill hot in pre-sterilized bottles, crown cork and process on boiling water for 20-25 minutes. On cooling, keep in cool and dry place. Sodium benzoate can be used as preservative.

3. Cashew apple jam and candy: Immerse the cashew apples in 3% salt solution for 3 days to remove astringency (tannins), followed by steaming for 15-20 minutes. Extract the pulp and prepare jam as per standard practice. In case of candy the sugar strength is kept 450Brix and is increased @ 50Brix for 4 days and then @ 100Brix for 6th and 7th day so that the final strength of syrup reaches to 700Brix. Keep in this solution for 8-10 days for complete absorption of sugar. Remove the pieces from syrup and dry.

4. Cashew kernels peel tannin: Kernel peel are a rich source of tannin (25%), which is in great demand by leather industry.

5. Cashew Nut Shell Liquor (CNSL): It is a byproduct obtained during separation of cashew kernel. It is viscous dark liquid and is extremely corrosive. It is used as raw material for phenolic resins and friction powder in automobile industry. It is also used as moulding acid resistant paints, found in any resins, varnishes and as insecticide/ fungicides etc.

6. Cashew kernels oil: Low grade kernels are processed in to kernel oil (30-40%) which is of high quality.

7. Cashew kernel butter: Kernel residue after extraction of kernel oil used to produce cashew kernel butter which is similar to peanut butter.

F. COCONUT
Coconut (Cocos nucifera L.) is most useful palm belonging to family Palmae. In India, coconut tree is called as kalpvriksha the tree of life, coconut is grown in a wide range of agro-climatic conditions. Productivity of coconut in India in terms of nuts/hectare is highest among major coconut growing area. Coconut is mainly consumed as raw nuts, copra and oil, whereas other products are coir and nuts. Coconut oil is the main commercial product. Copra obtained after drying kernel of coconut contains 65-70 % oil. Copra is used to extract coconut oil and coconut meal in the ratio of 3:2. The products like hair oil, soaps, shampoos and medicine use coconut oil as a main ingredient. In India, only 10% of the production is used for tender nut water. Traditionally, coconut industry in India is centered on copra making, coconut oil extraction and coir manufacture. The industrial products are desiccated coconut, cream milk powder, vinegar, nata-de-coco etc.

Coconut Products: following products are made from coconut on a commercial scale.
  1. Copra
  2. Coconut oil
  3. Raw kernel
  4. Coconut cake
  5. Tender coconut water
  6. Coconut toddy
  7. Coconut shell based products
  8. Coconut wood based products
  9. Coconut leaves
  10. Core pith
     
1. Copra: The dried coconut endosperm is called copra with oil content of 65% to 70% copra is the richest source of fat. The focus of copra are made in our country namely milling copra and edible copra, milky copra is made in the form of cups used for oil extraction. It is also used as a dry fruit for consumption.
Whole, edible copra is shredded and used as garnish in various dishes. Drying of copra can be carried out in open sun or in hot air driers. Even electrical and solar driers can also be used. Sun drying takes 6-8 days while hot air driers involve 20-24 hours for drying. During drying the moisture content from 50-55 % is reduced to 5-6 %. Dried copra should be packed in polyethylene lined gunny bags and stored ion cool and dry place.
  • copra: it is made in the form of cups and balls.
  • Ball copra: fully ripe nuts of 12-14 months are stored in upper floor of specially made store (two storied brick and mortar building). The floor and four sides of upper story and smoked by a slow fire set under the platform using coconut palm waste. During this period, the water inside the nut dries up and kernel gets detached from shell and raffles on shaking. The process completes in 8-12 months. Small sized nuts are preferred over large sized one.
  • Edible cup copra: nuts stored as above for shorter period are used for making edible cup copra. The copra balls are cut into halves and then they are sun dried for a few days.
2. Coconut oil: Coconut oil is extracted from milling copra. The pulped copra is fed continuously to the expeller from which oil and cake are expressed. Hydraulic pressing of cake also results in extraction of copra oil. Coconut oil is very low in unsaturated and polyunsaturated fatty acids, particularly linoleic acid as compared to other vegetable oils (Kumar et al. 2000). It is more resistant to oxidation than many other types of oils. It is obtained from mature meet which when dried contain 65% oil and the oil obtained from coconut milk is called as virgin coconut oil. Coconut oil is used for culinary, edible purposes and for industrial use like toiletries and soap making etc. Coconut oil processing methods are classified into two major types: dry and wet processes. When the oil is extracted from copra as raw material is termed as dry process, while use of fresh coconut as starting material is called wet process.

3. Coconut water: Water from tender coconut (7-8 month old) is a refreshing drink, effective in cases of gastroenteritis, diarrhea, vomiting and in preventing dehydration. The nut water is less nutritious from mature coconut as compared to tender coconut water. Nata-de-coco, soft drink, vinegar, food yeast etc are the products in which coconut water is main source. Coconut water can also be used to produce carbonated and non-carbonated beverages as refreshing and more nutritious drinks than other similar products.

4. Coconut meat: The kernel of seven to eight month old nut is very soft with maximum contents of protein and sugar. Kernel is as such consumed or with sweet nut water. Fresh kernel is consumed in the grated form and in the form of milk or cream obtained by squeezing the grating with or without addition of water. As the nuts turn more mature the quality decreases gradually. Fresh coconut meat contains 50-55% moisture which is to be brought down to 5-6% during drying.

5. Coconut milk or cream: Coconut milk or cream is the oil-protein-water emulsion obtained by freezing grated fresh coconut kernel. It is the processed milk extracted from fresh matured coconuts. It is the processed milk extracted from fresh matured coconuts. It is used either directly or diluted with water to make various preparations like curries, sweets, puddings and many bakery preparations. Processed and packed coconut cream has a shelf life up to three months.

6. Instant coconut milk powder: It is a spray dried product similar to dairy milk powder. The spray dried coconut milk powder if dissolved in water, results in coconut milk which can be used in place of fresh coconut milk for food preparation.

7. Desiccated coconut (DC): Desiccated coconut is the white kernel of fresh coconuts, shelled and dried to about 2.5% moisture content with high nutritional value. The common grade of desiccated coconut has particle size less than 5 mm. It is an important commercial product with a wide demand in confectionary and other industries, like chocolate and liquorice. The desiccated coconut contains moisture 2.5%, oil 67.5%, protein 5.9%, carbohydrates 5.9%, ash 9.3% and fibre 2.4 percent.

8. Coconut husk products: The coconut husk usually forms 35-45% of the whole nut weight at ripening. About 30% of husk is fibre and 70% is the coir dust. Coir pith is used as manure, as mulch or in making briquettes with good export potential. Coconut husk is the basic raw material for coir industry. The fibres extracted from coir is used for spinning into yarn for making mats, ropes, rugs, carpets, bleaching, dyeing, printing, poly coir, coir matting decorated boards, husk particle boards etc.

9. Coconut shell powder: it is made from matured coconut shells and is used in plywood and laminated board industry as a phenolic extruder and as filler in synthetic resin ghees, mosquito coils and agarbatis.

10. Other products: Coconut sap, coconut syrup and sugar, fermented coconut sap, coconut vinegar, coconut shell powder, coir fibre and pith are some of the important coconut products.


G. OILPALM

Oil palm ( Elaeis guinensis) is monoecious, cross pollinated plant placed in the Arecaceae family along with coconut and date palms. It is native to West Africa. Oil palm is the highest oil producer among all perennial oil yielding crops. Fruit of oil palm is drupe. It consists of exocarp, mesocarp and endocarp surrounding the kernel. The kernel has a testa, a solid endosperm and an embryo. It produces two distinct oils viz palm oil (extracted from mesocarp of fresh fruits) and palm kernel oil extracted from kernels. The yield of palm oil ranges between 20-30%.

Processing of oil palm: The palm oil processing consist of threshing of bunches, heating of fruit, digestion, pressing, clarification/ drying and storage. The unit operation used in processing of oil palm for extraction of oil given in Fig 15.3 is explained as under:

1. Threshing: The fruit bunches consist of fruit embedded in spikelets growing on a main stem. For extraction of oil heating of fruit or bunches is necessary as it performs many functions. At small scale operation, bunches are threshed manually to separate the part from the spikelets and threshed fruits are cooked. While at large scale operation, bunches are heated using high pressure sterilization system which helps in loosening of fruits.

2. Sterilization of bunches: Sterilization of bunches either by using hot water or steam under pressure serves the following operations:
  • To destroy oil splitting enzymes and to arrest hydrolysis and autoxidation.
  • To weaken fruit stem to help in removal of fruit from bunches on shaking or tumbling in threshing machine.
  • To solidify proteins to allow oil bearing cells to come together and flow more easily on application of pressure.
  • To weaken pulp structure in fruit to help in easy detachment of fibrous material and its contents during digestion process.
  • Steaming breakdown gums and resins which are removed during oil clarification.
  • High pressure steam cause separation of moisture in nuts. When pressure is reduced, contraction of nuts leads to detachment of kernel from shell wall, thus loosening kernels within their cells. Detachment of kernel from the shell wall facilitates nut cracking.

3. Digestion of fruit: It refers to the process of releasing palm oil in the fruit through rupture of oil bearing cells. Digestion consists of steam heated cylindrical vessel fitted with central shaft carrying better arms for stirring. Through action of rotating beater arms, the fruit is pounded. Pounding or digesting fruit at high temperature, helps to reduce viscosity of oil, destroys out covering (exocarp) of fruit and cause disruption of oil cells.

4. Pressing/extraction of oil: Oil can be extracted either by dry method or wet method. In dry method oil is extracted by using mechanical press while in wet method hot water is used for leaching out the oil from the digested material. Either batch press or screw press can be used for oil; extraction.

5. Clarification and drying of oil: Clarification is done to separate oil from impurities. The fluid coming out of press is a mixture of palm oil, water cell debris, fibrous material and non oily solids. Presence of non-oily solid make the mixture very viscous (thick). The mixture is therefore, diluted by adding hot water in 3:1 proportion.
The diluted mixture is passed through a screen to remove coarse fibre. The screened mixture is boiled for 1-2 hours and then allowed to settle in large tanks. The clear oil is decanted and reheated in a cooking pot to reduce moisture content to 0.15-0.25%. Continuous clarifier consisting of three components heat the crude mixture, dry the decanted oil and hold the finished oil in an outer shell as a heat exchanger.

6. Storage of oil: The purified and dried oil is stored in plastic drums or in other suitable containers and stored at ambient temperature.

7. Palm kernel oil extraction: The residue left after extraction of palm oil from fruits contain mixture of fibre and palm nuts. The nuts are separated manually or in depreciation. The nuts are then dried and cracked in centrifugal crackers to release the kernels. Breaking of kernels should be avoided as it increases the free fatty acids in the oil. The kernels are then separated from the shells using a combination of winnowing and hydro-cyclones. The kernels are dried in silos to a moisture content of 7% before packing and use for kernel oil extraction. The palm kernel oil is extracted by using following three unit operations

(i) kernel pretreatment
(ii) screw pressing
(iii) oil clarification.

i) Kernel pre-treatment: The kernels after cleaning are broken into small fragments by using either hammer grinder or breaker rolls or combination of both. The kernel fragments are flaked (0.25-0.4 mm thick) in a roller mill. The kernel flakes are then placed in stack cooker for steam conditioning which adjust the moisture content to optimum level, rupture cell wall, reduce viscosity of the oil and coagulates the protein in the meal to facilitate release of oil from pertinacious material. In palm kernel, the meal is cooked to a moisture content of 3% at 104-110oC.

ii) Screw-pressing: Properly cooked meal is fed to screw-press, which consists of an interrupted helical thread (worm) which revolves within stationary perforated cylinder called cage or barrel. The meal is forced through the barrel by action of revolving worms. The expelled oil flows through the lining bars of barrel while de-oiled cake is discharged through annular orifice.

iii) Oil clarification: The expelled oil sometimes contains solid impurities thus the oil is drained to a reservoir. The oil is pumped to a decanter or revolving coarse screen to remove large part of impurities. After this, the oil is pumped to a filter press to remove remaining solids and fines to get clear oil. The cake from the press is collected separately.

Palm oil, olein and stearin are used worldwide in making margarine, in shortening and confectionery and in snack foods frying. Palm oil is also used in the manufacturing of soaps, detergents and other surfactants. It is good raw material for production of oleo-chemicals, fatty acids, fatty alcohols, glycerol and other formulations for cosmetics, household and industrial products.
15.2

H. RUBBER (Hevea brasiliensis)
Rubber tree is the most important source of natural rubber and meets around 98% of the global requirement. The rubber belongs to family Euphorbiaceae and its economic product rubber is a cis-poly-isoprenic molecule found in latex. Latex is found in all the plant parts like bark of trunk, roots, branches, leaves, flower, fruits and seeds. Commercially the latex present in the bark of trunk of mature tree is exploited. The latex consuming industry is virtually separate from the remainder of the rubber consuming industry. Natural rubber is a high molecular weight polymer and is used for the manufacture of medical gloves. Other products manufactured from latex include catheters and condoms (prophylactics), garment threads (used in garment manufacture) and foam (in pillows and mattresses) etc. The latex consists of 30-40% rubber, 1-2% resins, 55-65% water, 2-2.5% proteins, 1-1.5% sugars and 0.7-0.9% ash. Latex obtained from rubber tree is the basic raw material for extraction of rubber and its processing inot different forms.
Methods used commercially are discussed here under:
Latex is obtained from the bark of rubber tree by tapping. Tapping is a process of controlled wounding during which thin shaving of bark is done. The purpose of tapping is to cut open latex vessels from the trees (used for first time) or to remove coagulum which otherwise block cut ends of latex vessels in case of trees under regular tapping. Tapping is done early in the morning when turger pressure for exudation of latex is maximum. For tapping and collection of latex knives, spout, cup hauzers, collection cups. Collection buckets and scrap buckets are used. Michie Golledge Knife and Jebong Knife are used for tapping however, for controlled upward tapping modified gauge knife is used. Different types of tapping include intensive tapping, high level tapping. Controlled upward tapping, puncture tapping, slaughter tapping etc.

Crop collection: The main crop from rubber plantation is latex, which is harvested by tapping process. 2-3 hours after tapping, latex collected in the crop is transferred to a clean bucket. About 70-80% of the crop from a rubber plantation is in the form of latex. The latex which gets solidified in tapping panel and collection cups or overflowed to the ground and gets dried up is also collected. This is collectively called as field coagulum.

Processing of latex: For long term storage and marketing the latex and field coagulum are processed in different forms such as preserved field latex, latex concentrate, sheet rubber, block rubber and crepe rubber. Field coagulum is generally processed only in the form of Crepe rubber or black rubber.

Latex can be processed into any of following forms
1. Preserved field latex: Field latex is preserved by using ammonia (1%), LATZ (low ammonia 0.2-0.3%) as preservative for long term storage. The processing of preserved latex consists of adding preservative to the sieved latex, bulking, settling, blending and packing.

2. Latex concentrate: Latex is concentrated by using either creaming or centrifugation method.

a) Concentration by creaming: In this method, creaming agents like ammonium alginate or tamarind seed powder is mixed with preserved latex and allowed to settle for some time. This treatment separates the mixture in to two layers. The upper layer contains concentrated latex while, lower layer of serum containing very little rubber. The lower layer of serum is removed, whereas, upper layer containing latex concentrate having 50-55% dry rubber contents is collected, packed and marketed.
b) Concentration by centrifugation: Centrifugation separates preserved field latex into two fractions, one containing concentrated latex (having more than 60% dry rubber) and other containing about 4-8% dry rubber. Skim latex is generally coagulated with H2SO4, made into crepe, dried and marketed as skim rubber, which is low grade rubber.

3. Sheet rubber: Latex is coagulated in container into thin slabs of coagulum and rolled with rollers followed by drying to get sheet rubber. On the basis of method of drying, sheet rubber is classified in to two types i.e., ribbed smoked sheets and air dried sheets.
Preparation of Sheet rubber

a) Straining and dilution of latex: For preparation of sheet rubber, the latex is processed immediately before pre-coagulation sets in. Anti-coagulation can also be added to prevent pre-coagulation of latex. The latex is strained through 40 and 60 mesh stainless steel sieves and diluted in bulking tanks to a standard consistency of 0.5kg dry rubber for every 4 litre of diluted latex (12.5% dry rubber contents). It is then allowed to stand in bulking tank for 15-20 minutes for sedimentation of heavy dirt particles. The clear diluted latex is decanted in coagulation pans.

b) Coagulation: For coagulation, diluted formic acid or acetic acid is mixed with latex. To prevent surface darkening small quantity of sodium bisulphate (1.2 kg/kg dry rubber content) dissolved in water is added to the diluted latex before coagulation. After coagulation, the coagulum is removed from the pan and washed thoroughly in running water. It is then rolled either in sheeting battery or smooth rollers to a thickness of 3mm and finally passed through grooved rollers. While sheeting, the coagulum is continuously washed in running water in a tank.
To prevent mould growth on rubber sheet the freshly machined sheet is treated with dilute solution (0.05-0.1%) of para-nutrophenol (PNP). About 100 litres of 0.05-0.1% PNP solution is sufficient for treating 100 sheets. The wet sheets are then allowed to drip on reapers arranged in a well ventilated dripping shed.

c) Smoking/drying: The sheets after 2-3 hours of dripping in shade are placed in smoke house, where the temperature in maintained between 40-60oC. In the smoke house, sheets are dried gradually to avoid blisters. Besides, the creostatic substances present in the smoke also prevent mould growth on smoked sheets. 4-6 days of smoking is sufficient for drying of sheets.
The smoke house is a chamber in which sheets are placed on the reapers for drying. Smoke houses are of two types, those in which furnace is inside drying chamber and those in which furnace is outside the chamber. Rubber sheets can also dried by using any of the drying system such as solar cum smoke drying, sun drying or air drying.

d) Storage: Sheets after grading are packed in 50kg bales. There are six International grade descriptions for sheet rubber i.e., RSS IX, RSS 1 to RSS 5.

4. Crepe rubber: These are processed from fresh latex coagulum, field coagulum or cutting of rubber sheets (ribbed smoked sheets). The material is passed through a set of crepe making machines and a lace like rubber is obtained. This rubber on drying results in crepe rubber. Latex crepe and field coagulum crepe are two typesof crepe rubber depends upon which the raw material used.

i) Latex crepe: Latex crepe rubber is of two types i.e., Pale latex crepe (PLC) and sole crepe. The latex used for these two types shall be free from yellow pigments and enzymic discolouration.

ii) Field coagulum crepe: The unit operations used in making field coagulum is soaking of coagulum in water, crepe making, drying, grading and packing. The crepe prepared from field coagulum materials falls into five types.

a) Estate brown crepe: It is made from the cup lumps and other higher grades of field coagulum.
b) Thin brown crepe: It is made from wet slab coagulum as starting material.
c) Thick blanket crepe: it is made from wet slabs, unsmoked sheets or other high grade scraps.
d) Smoked blanket crepe: It is derived from ribbed smoked sheets or cuttings
e) Flat bark crepe: In this all types of low grade scrap including earth scrap is used.

5. Technically specified rubber (TSR): TSR is marketed with quality certification from Bureau of Indian Standards, under the name of Indian Standard Natural Rubber (ISNR). It is produced from both latex and field coagulum and available in six grades of BIS specifications. Basic unit operation involved in manufacture of TSR includes size reduction, dewatering, dirt removal, drying, blending, grading and packing. Slab cutter, coagulum crusher, prebreaker, macerator/crepe roller, hammer mill/shredder drier and baking press are important machineries used in performing these unit operations. TSR bales are generally packed in low-density polyethylene (LDPE) bags.


Last modified: Wednesday, 7 March 2012, 7:11 AM