TURMERIC

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PROCESSING
 

  • It involves three stages viz., curing, polishing and colouring.

Curing

  • Fingers are separated from mother rhizomes and are usually kept as seed material.
  • The fresh turmeric is cured for obtaining dry turmeric before marketing.
  • Curing involves boiling of fresh rhizomes in water and drying in the sun.
  • Pests and diseases like shoot borer and soft rot still cause havoc to the crops.
  • There are no disease resistant varieties of turmeric available in India.

Traditional method of curing is as follows

  • The cleaned rhizomes are boiled in copper or galvanised iron or earthern vessels, with water just enough to soak them.
  • In certain places, cowdung slurry is used as boiling medium. From hygienic point of view, such rhizomes fetch poor market value.
  • Boiling is stopped when froth comes out and white fumes appear giving out a typical odour.
  • The boiling lasts for 45 to 60 minutes when the rhizomes are soft.
  • Overcooking spoils the colour of final product while undercooking renders the dried product brittle.
  • A boiler has been developed at Tamil Nadu Agricultural University, Coimbatore for bleaching of turmeric rhizomes, 150 kg of fresh rhizomes could be cooked in this boiler, which costs around Rs. 1200/-.

The improved scientific method of curing is as follows

  • The cleaned fingers (approximately 50 kg) are taken in a perforated trough of size 0.9 x 0.55 x 0.4 m. made of GI or MS sheet with extended parallel handle.
  • The perforated trough containing the fingers are then immersed in the pan.
  • The alkaline solution (sodium carbonate or sodium bicarbonate at 1g/lit) is poured into the trough so as to immerse the turmeric fingers.
  • The whole mass is boiled till the fingers become soft.
  • The cooked fingers are taken out of the pan by lifting the trough and draining the solution into the pan.
  • Alkalinity of the boiling water helps in imparting orange yellow tinge to the core of turmeric.
  • The drained solution in the pan can also be used for boiling another lot of turmeric along with the fresh solution prepared for the purpose.
  • The cooking of turmeric is to be done within two or three days after harvesting.
  • The mother rhizomes and the fingers are generally cured separately.
  • The cooked fingers are dried in the sun by spreading 5 to 7 cm thick layers on bamboo mat or drying floor.
  • A thinner layer is not desirable, as the colour of dried product may be adversely affected.
  • During night time, the materials should be heaped or covered.
  • It may take 10 to 15 days for the rhizomes to become completely dry.
  • The yield of the dry product varies from 20 to 30 per cent depending upon variety, the location where the crop is grown, cultivation practices and agroclimatic conditions.

Polishing

  • Dried turmeric has poor appearance and a rough dull outer surface with scales and root bits.
  • The appearance is improved by smoothening and polishing outer surface by manual or mechanical rubbing.
  • Manual polishing consists of rubbing the dried turmeric fingers on a hard surface or trampling them under feet, wrapped in gunny bags.
  • The improved method is by using hand operated barrel or drum mounted on a central axis, the sides of which are made of expanded metal mesh.
  • When the drum filled with turmeric is rotated at 30 rpm, polishing is effected by abrasion of surface against the mesh as well as by mutual rubbing against each other as they roll inside the drum.
  • The turmeric is also polished in power operated drums.
  • The yield of polished turmeric from the raw materials varies from 15 to 25 per cent.

Colouring

  • It is done to give appearance and better finish to the product, since the colour of the turmeric always attracts buyers.
  • This is done to half polished rhizomes in two ways, known as dry and wet colouring.
  • In dry process, turmeric powder is added to the polishing drum in the last 10 minutes.
  • In wet process, turmeric powder is suspended in water and mixed by sprinkling inside the polishing basket.
  • For giving a brighter colour, the boiled, dried and half polished fingers are taken in baskets which are shaken continuously when an emulsion is poured in.
  • When the fingers are uniformly coated with the emulsion, they may be dried in the sun.
  • The composition of the emulsion required for coating 100 kg of half boiled turmeric is

Alum

0.04 kg,

Turmeric powder

2.00 kg,

Castor seed oil

0.14 kg,

Sodium bisulphate

30.00 g

Concentrated hydrochloric acid

30.00 ml.

Improved methods of curing

  • The Central Food Technological Research Institute (CFTRI), Mysore has developed a simpler, hygienic and efficient technique of curing and colouring turmeric.
  • In this method, rhizomes are boiled in lime water or sodium carbonate. A water solution containing 20 g of sodium bisulphite and 20 g of hydrochloric acid per 45.3 kg of tubers is recommended to give them the desired yellow tint.

Do's and Don'ts in processing

Do's

  • Choose the best suited variety to each region for which the service of the concerned agricultural officer may be sought.
  • Seed turmeric should be immersed in suitable solution of fungicide and insecticide after harvest for half an hour. Then dry in shade and keep safely.
  • The place selected for storage of seed-turmeric should be free from moisture and away from sun light and rain.
  • Different varieties mature at different times. So varieties should not be mixed and cultivated together.
  • Mother rhizomes are the best for seeds. Larger rhizomes can be split and used.
  • If pest infestation is noticed, follow management practices as per the instructions of the nearby agricultural officer.
  • Remember curcumin content of the turmeric will decrease, if harvested before maturing.
  • Rhizomes should be harvested without damage and cuts.
  • After harvest, rhizomes may be washed by a water jet to remove the mud and dirt adhering to them.
  • Immediately after harvest, turmeric should be boiled and dried.
  • For boiling turmeric, use clean water.
  • The 'bulb' and the 'finger' should be boiled, dried and marketed separately.
  • Before boiling, water should be filled to cover rhizomes, put a gunny bag or jute bag over turmeric to restrain the steam loss.
  • Heating should be uniform.
  • Turmeric should be sufficiently boiled. It will take 45 to 60 minutes to complete the cooking of turmeric after the first boiling. It can be tested by pressing between fingers or by piercing a small stick through the turmeric. If it is easily pierced, it indicates thorough cooking. The typical odour of the vapour too indicates that it is fully cooked.
  • Clean terraces of cemented yards or clean bamboo mats should be used for drying turmeric.
  • It should be heaped and covered during night in order to protect from rain. If the turmeric happens to get wet by rain during drying the yellow colour may change to orange red.
  • Dried turmeric may be marketed after polishing.
  • In order to make the produce attractive, turmeric powder may be sprinkled during the last phase of polishing.
  • After polishing, it should be marketed without delay, if not, it should be kept in clean sacks and stored over wooden pallets in stores.
  • Stores should be kept clean, free from infestation of pests, spiders, psocids and rodents.

Don'ts

  • Don't cultivate turmeric at the same site continuously.
  • Don't choose varieties that are unsuited to the soil and climate.
  • Pest/disease affected turmeric rhizomes should not be used.
  • Rhizomes of small size or low weight should not be used.
  • 'Bulb' and 'finger' should not be boiled together.
  • Turmeric prepared for boiling should not contain mud and dirt.
  • Harvested turmeric should not be delayed more than 2 days to boil.
  • Disease or pest infested turmeric should not be used for processing.
  • No chemical or other materials should be added to the water used for boiling,
  • Cow-dung pasted floor or mats should not be used for drying.
  • Cow-dung pasted containers should not be used to handle turmeric.
  • Extraneous matters should not be allowed to get contaminated with turmeric.
  • No colouring materials should be added while polishing other than turmeric powder.
  • Pesticides should not be applied on the dried/polished turmeric to prevent storage pests.
  • Properly dried and half dried turmeric should not be mixed.
  • Turmeric should not be stored in dirty sacks, bags or containers.

Storage

  • The assembling markets in Erode stock the rough dried turmerics in underground pits made in elevated ground.
  • The polished turmeric is stored in double gunny bags in ware houses.
  • Well dried turmeric (< 5% moisture) is not susceptible to any mould growth/disease problem.

Storage pest management

  • Insects feed on stored dried turmeric and thus account for serious damage and loss.
  • The important insect species responsible for loss in stored turmeric are as follows:

Common Name

Scientific Name

Cigarette or tobacco beetle

Lasioderma serricorne

Drug store or spice beetle

Stegobium paniceum

Red flour beetle

Tribolium castaneum

Saw toothed grain beetle

Oryzaephilus surinamensis

Arecanut beetle

Araecerus fasciculatus

Cadelle

Tenebroides mauritanicus

Fig moth

Ephestia sp.

Meal snout moth

Pyralis manihostalis

  • Cigarette beetle and drug store beetle are very important insect pests attacking dry turmeric in storage.

Cigarette or tobacco beetle, Lasioderma serricorne

  • As the name indicates, it is primarily a pest of stored tobacco.

Symptom

  • The grub feeds on stored turmeric by making circular pinhead sized bore holes.

Loss

  • Infestation by this pest resulted in a weight loss of 39.78 per cent.
  • Sixty eight per cent of turmeric samples collected were infested with L.serricorne

Biology

  • The light brown round beetle has its thorax and head bent downward and this presents a strongly humped appearance to the insect.
  • The elytra have minute hairs on them.
  • Antenna is of uniform thickness.
  • The whitish hairy grubs feed on stored tobacco, ginger, turmeric and chillies.
  • The creamy white oval eggs are laid on the surface of stored material.
  • The incubation period is 9 to 14 days.
  • The larval and pupal periods range respectively from 17 to 29 days and 2 to 8 days.
  • The beetles live for 2 to 4 weeks and during that period, the females lay as many as 100 eggs each.

Management

  • Fumigation with phosphine gas from Aluminium Phosphide (celphos) tablet at 3 to 4 tablets/tonne in an air tight store for 2 to 3 days resulted in total mortality of the pest.

Drug store beetle, Stegobium paniceum

  • It is a very general feeder and gained its common name from the frequency with which it was found feeding on drugs in pharmacies.

Symptom

  • The grub feeds on dry turmeric by making circular pin head sized bore holes.

Biology

  • The reddish brown small beetle has striated elytra and measures 3mm long.
  • Antenna is clubbed.
  • It lays the eggs in batches of 10 to 40.
  • Grub is not hairy but is pale white, fleshy with the abdomen terminating in two dark horny points.
  • It tunnels into stored products like turmeric ginger, coriander and dry vegetables and animal matter.
  • The larval and pupal periods occupy respectively 10 to 20 days and 8 to 12 days.

Management

  • Similar to that of cigarette beetle.
  • The other storage pests viz., red flour beetle, saw toothed grain beetle, arecanut beetle, cadelle fig moth and meal snout moth are of minor importance in turmeric. Fumigation of the stored material will take care of all the storage pests.

Fumigation

  • Decide the need for shed fumigation (entire store house or godown) or cover fumigation (only selected blocks of bags)
  • Check the store house/godown and the black polythene sheets or rubberised aluminium covers for holes and get them ready for fumigation.
  • Choose the fumigant and work out the requirement based on the following guidelines.

Aluminium phosphide

  • For cover fumigation: 3 tablets of 3 g each per tonne of grain/dry turmeric.
  • For shed fumigation: 21 tablets of 3 g each for 28 cubic metres.
  • Period of fumigation: 5 days
  • In case of cover fumigation, mix clay or red earth with water and make it into a paste form and keep it ready for plastering all round the fumigation cover or keep ready sand-snakes.
  • Insert the required number of aluminium phosphide tablets in between the bags in different layers.
  • Cover the bags immediately with fumigation cover.
  • Plaster the edges of cover all round with wet red earth or clay plaster or weigh down with sand-snakes to make leak proof.
  • Keep the bags for a period of 5-7 days under fumigation based on the fumigant chosen.
  • Remove the mud plaster after specified fumigation period and lift cover in the corner to allow the residual gas to escape.
  • Allow aeration and lift cover after a few hours.
  • Follow similar steps to ensure leak proof condition, fumigation period, aeration etc., in case of shed fumigation.
  • Fumigants are used for curative treatment and they have no residual action on new immigrant insects which can infest grain.
  • Sample periodically and fumigate stored material based on need.
  • Handle fumigants with utmost care as per specifications.
  • Fumigation should be carried out only by trained persons.

 

 
 
 

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