Figure 1: Fresh turmeric root. Photo: Practical Action/Neil Noble

This page describes the details of turmeric processing.

Introduction[edit | edit source]

Turmeric (Curcuma domestica) is an erect perennial plant that is grown as an annual crop for its rhizome. It belongs to the same family as ginger (Zingiberaceae) and grows in the same hot and humid tropical climate. The rhizome is a deep bright yellow colour and similar in size and form to the ginger rhizome. The plant originated in the Indian sub-continent and today India is the worlds leading producer and consumer of turmeric. It is also produced in China, Taiwan, Bangladesh, Indonesia, Sri Lanka, Australia, Africa, Peru and the West Indies. Turmeric plays an important role in Indian culture- it is an essential ingredient of curry, used in religious festivals, as a cosmetic, a cloth dye and in many traditional health remedies. The spice is sometimes referred to as 'Indian saffron'.

Turmeric production[edit | edit source]

The Turmeric plant is propagated by planting pieces of the previous season's rhizome, which grows to form plants of about 0.9 metres tall. The plant has long stemmed leaves and pale yellow flowers and requires a loamy soil. It grows in a wide range of climatic conditions, but does require rainfall of between 1000 and 2000mm a year. It can grow in locations that are up to 1220m above sea level.

Harvesting[edit | edit source]

Turmeric is harvested when the plants are between 7 and 10 months of age, when the stems and leaves start to dry out and die back. The whole plant is removed from the ground, taking care not to cut or bruise the rhizomes.

Sweating[edit | edit source]

The leaves are removed from the plant and the roots carefully washed to remove soil. Any leaf scales and long roots are trimmed off. The side (lateral) branches (which are known as the fingers) of the rhizomes are removed from the main central bulb (known as the mother). The mothers and fingers are heaped separately, covered in leaves and left to sweat for one day. The 'mothers' are the preferred material for planting the following year.

Curing[edit | edit source]

Before drying, the turmeric rhizomes have to be cured. This involves boiling the roots to soften them and remove the raw odour. After curing, the starch is gelatinised, which reduces the drying time required, and the colour is uniformly distributed throughout the rhizome. The specifications for curing turmeric vary from different places. The Indian Institute of Spice Research and the Agricultural Research Centre recommend boiling in plain water for 45 minutes until froth appears at the surface and the typical turmeric aroma is released. Using this method, the colour will deteriorate if the rhizomes are boiled for too long. However, if not boiled for long enough, the rhizome will be brittle. The optimum stage is reached when the rhizomes are soft to touch or can be pierced by a blunt piece of wood.

Other researchers recommend boiling the rhizomes in an alkaline solution, made from 0.05% to 1.0% sodium carbonate or lime (calcium carbonate). The alkaline water is thought to improve the final colour of the dried turmeric. Because the fingers and bulbs are of different size and thickness to each other, it is important that they are cured in different batches. The curing time is dependent on the age, variety and size and thickness of the rhizomes and varies from one to four or six hours. It is also affected by the size of the batch – smaller batches generally produce a higher quality dried turmeric as the curing process is easier to control and monitor. It is recommended to use perforated containers with a capacity of 50-75kg. The perforated containers are immersed in the boiling water for the required cooking time. This method allows the boiling water to be used for more than one batch of turmeric. The best time for curing is two to three days after harvest. If it is delayed after this then the rhizomes may start to deteriorate. The benefits of curing turmeric include the following:

  • Reduction of drying time
  • More even colour distribution throughout the rhizome
  • A more attractive (not wrinkled) product that is easier to polish
  • Sterilisation of the rhizomes before drying.

Drying[edit | edit source]

The rhizomes are sliced before drying to reduce the drying time and improve the quality of the final product (it is easier to achieve a lower final moisture content in small pieces of rhizome without spoiling the appearance of the product). The rhizomes are traditionally sliced by hand, but there are small machines available to carry out this process. Figure 2 is a simple turmeric slicing machine designed in Bolivia. It is a simple structure that contains a transmission system and two stainless steel circular blades. The machine is easy to build and maintain and can cut up to 120kg turmeric per hour.

Figure 2: A simple slicing machine used in Bolivia( 02.htm)

The cooked fingers or bulbs are dried until they have a final moisture content of 5-10%. An experienced turmeric processor. will know when the rhizome is dry enough as the fingers will snap cleanly with a metallic sound. Traditionally the rhizome pieces are laid on clean concrete floors and dried in the sun. This method can take anything from 10 to 15 days, depending on the climate and the size of the rhizome pieces. It is important that the rhizome pieces are not placed in direct sunlight as this will cause the colour to fade. Using a mechanical drier will result in a better colour and a higher quality product.

There are several different types of mechanical drier that are suitable for drying turmeric. These include the tray drier, cross flow air tunnels, solar driers and cabinet driers. The optimum drying temperature is 60°C – temperatures higher than this result in a darker coloured product. See the (Practical Action Technical Brief) on drying for further general information on driers.

Figure 3: A typical tray drier
Figure 4: A typical solar drier developed in Bolivia 02.htm

Polishing[edit | edit source]

After drying the rhizomes are polished to remove the rough surface. This can be done by hand or by shaking the rhizomes in a gunny bag filled with stones. Polishing drums are used in many places – these are very simple, power driven drums that have an abrasive metallic mesh lining. In some places the rhizomes are sprinkled with a solution of ground turmeric in water during the final polishing, to give the rhizomes a good colour.

Grading[edit | edit source]

Quality specifications for turmeric are imposed by the importing country. They refer to the cleanliness of the product rather than on the eating quality. Bulk rhizomes are graded into fingers, bulbs and splits. The Indian standards for turmeric follow the Agmark Specifications (Agricultural Directorate of Marketing) to ensure quality and purity of the products.

Grade Flexibility Broken pieces, fingers <15mm- No more than (% by weight) Foreign matter-No more than (% by weight) Defectives- No more than (% by weight) Percentage of bulbs by weight max
Alleppey fingers (a)
Good Hard to touch 5 1 3 4
Fair Hard 7 1.5 5 5
Fingers other than Alleppey
Special Hard to touch, metallic twang on break 2 1 0.5 2
Good Same 3 1.5 1 3
Fair Hard 5 2 1.5 5
Rajapore fingers (b)
Special Hard to touch,metallic twang on break 3 1 3 2
Good Same 5 1.5 5 3
Fair Hard 7 2 7 5
Non Specified
- 4
Bulbs (c)
Special - - 1 1
- 1.5 3
2 5

Table 1: Agmark standards for turmeric rhizomes(

a Fingers shall be of secondary rhizomes of Curcuma longa L.; shall be well set and close grained; free from bulbs; be perfectly dry and free from weevil damage and fungus attack and not be artificially coloured with chemicals. b. Same as (a); have the characteristics of the variety; admixture of varieties of turmeric allowed at a maximum of 2%, 5%, 10% and 10% for the four grades respectively. c. Bulbs shall be primary rhizomes of Curcuma longaL.; shall be well developed, smooth and free from rootlets; have the characteristics of variety; be perfectly dry and free from weevil damage and fungus attack; not artificially coloured with chemicals.

Varieties of turmeric

Alleppey Comes from Kerala. Has a deep yellow colour with a high pigment content (6.5% curcumin). This type is popular in the USA.
Madras Comes from Tamil Nadu. Is a mustard colour with a lower pigment content (3.5% curcumin). This type is popular in the UK.
West Indian Comes from the Caribbean. It is a dull yellowish brown colour.

Table 2: Varieties of turmeric.

Grinding[edit | edit source]

Grinding can be a method of adding value to a product. However, in general it is not advisable to grind spices as they become more vulnerable to spoilage. The flavour and aroma compounds are not stable and will quickly disappear from ground products. The storage life of ground spices is much less than for the whole spices. It is very difficult for the consumer to judge the quality of a ground spice. It is also very easy for unscrupulous processors to contaminate the ground spice by adding other material. Therefore most consumers, from wholesalers to individual customers, prefer to buy whole spices.

Turmeric is one of the few spices that is usually purchased Figure 5: Ground turmeric. in a ground form. The whole rhizome pieces may be Photo: Practical Action / Neil Noble exported and then ground in the country of destination. Alternatively, the dried rhizomes may be ground at the place of origin.

Grinding is a very simple process that involves cutting and crushing the rhizomes into small particles, then sifting it through a series of screens of different mesh size, to get a fine powder. There are a range of grinding mills available, both manual and powered, of different capacities and which work in different ways. The traditional way to grind would be between two stones. The advantage of this method is that the turmeric does not get too hot during the grinding process. With some of the mechanical mills, such as a hammer mill, heat is generated during the grinding process, which can cause some of the volatile taste and aroma compounds to be lost. For higher quality ground turmeric, the grinding temperature should be kept as low as possible.

After grinding the powder is sieved through different mesh screens until a uniform, fine powder is obtained.

Grade Moisture (%w/w) max Total ash (%w/w) max Acid insoluble ash (%w/w) max Lead (ppm) max Starch (%w/w) max Chromate test
Turmeric powder (a)
Standard 10 7 1.5 2.5 60 Negative
Coarse ground powder (b)
Standard 10 9 1.5 2.5 60 Negative

Table 3: Agmark standards for turmeric powder ( a. Ground to pass through a 300 micron sieve b. Ground to pass through a 500 micron sieve

Packaging[edit | edit source]

Dried rhizomes and rhizome pieces are packed in jute sacks, wooden boxes or lined corrugated cardboard boxes for shipping.

Ground turmeric should be packaged in moisture proof, air-tight polyethylene packages. The packages should be sealed and labelled with attractive labels. The label needs to contain all relevant product and legal information – the name of the product, brand name (if appropriate), details of the manufacturer (name and address), date of manufacture, expiry date, weight of the contents, added ingredients (if relevant) plus any other information that the country of origin and of import may require (a barcode, producer code and packer code are all extra information that is required in some countries to help trace the product back to its origin). See the Practical Action Technical Brief on labelling for further information on labelling requirements.

Storage[edit | edit source]

The bulk rhizomes are stored in a cool and dry environment, away from direct sunlight. The bright colour of ground turmeric will fade when it is left in the light for a long period of time. Therefore the packets should be stored in a cardboard box, away from the sunlight. The storage room should be clean, dry, cool and free from pests. Mosquito netting should be fitted on the windows to prevent pests and insects from entering the room. Strong smelling foods, detergents and paints should not be stored in the same room.

Standards[edit | edit source]

US Government requirements and ASTA
Moisture (%) <9.0
Curcumin (%) 5-6.6
Volatile oil (%) <3.5
Extraneous matter (% by weight) 0.5
Mould (% by weight) 3.0

Equipment suppliers[edit | edit source]

This is a selective list of suppliers of equipment and does not imply endorsement by Practical Action.

This website includes lists of companies in India who supply food processing equipment.,,1b_0_32/fruit+processing/index.html


Acufil Machines S. F. No. 120/2, Kalapatty Post Office Coimbatore - 641 035 Tamil Nadu, India Tel: +91 422 2666108/2669909 Fax: +91 422 2666255 Email: products

Bombay Engineering Works 1 Navyug Industrial Estate 185 Tokersey Jivraj Road Opposite Swan Mill, Sewree (W) Mumbai 400015, India Tel: +91 22 24137094/24135959 Fax: +91 22 24135828 Email:

Planters Energy network (PEN) No 5, Power House 3rd Street N R T Nagar Theni 625531 Tamil Nadu, India Tel: +91 4546 255272 Fax: +91 4546 255271 Email:

Premium Engineers Pvt Ltd Plot No 2009, Phase IV, GIDC Vatva, Ahmedabad 382445 India Tel: +91 79 25830836 Fax: +91 79 25830965

Rank and Company A-p6/3, Wazirpur Industrial Estate Delhi – 110 052, India Tel: +91 11 7456101/ 27456102 Fax: +91 11 7234126/7433905 Email:

Industrias Technologicas Dinamicas SA Av. Los Platinos 228 URB industrial Infantas Los Olivios Lima Peru Tel: +51 14 528 9731 Fax: +51 14 528 1579

Ashoka Industries Kirama Walgammulla Sri Lanka +94 71 764725

Kundasala Engineers Digana Road Kundasala Kandy Sri Lanka Tel: +94 8 420482

Alvan Blanch Chelworth, Malmesbury Wiltshire SN16 9SG United Kingdom Tel: +44 1666 577333 Fax: +44 1666 577339

Mitchell Dryers Ltd Denton Holme, Carlisle Cumbria CA2 5DU United Kingdom Tel: +44 1228 534433 Fax: +44 1228 633555

Slicing machines

Central Institute of Agricultural Engineering Nabi Bagh Berasia Road Bhopal 462 038 Madhya Pradesh India Tel: +91 755 2737191 Fax: +91 755 2734016

Eastend Engineering Company 173/1 Gopal Lal Thakur Road Calcutta 700 035 India Tel: +91 33 25536937 Fax: +91 33 23355667

Gardners Corporation 158 Golf Links New Delhi 110003 India Tel: +91 11 3344287/3363640 Fax: +91 11 3717179

Cleaning/abrasive machines

Central Institute of Agricultural Engineering India (see above)

Gardners Corporation India (see above)

Rajan Universal Exports Post Bag no 250 162 Linghi Chetty Street Chennai 600 001 India Tel: +91 44 25341711/25340731/25340751 Fax: +91 44 25342323

Narangs Corporation P-25 Connaught Place New Delhi 110 001 India Tel: +91 11 2336 3547 Fax: +91 11 2374 6705

DISEG Av Jorge Carlos Mariategui 1256 Villa Maria del Triunfo Lima Peru Tel: +51 14 283 1417

Servifabri JR Alberto Aberd No 400 Urb Miguel Grau (Ex Pinote) San Martin de Porres Lima Peru Tel/Fax: +51 14 481 1967

Servifabri SA Peru (see above)

Crypto Peerless Ltd Bordesley Green Road Birmingham B9 4UA UK

Milling and grinding machines

Central Institute of Agricultural Engineering India (see above)

Gardners Corporation India (see above)

Premium Engineers PVT Ltd India (see above)

Rajan Universal Exports PVT Ltd India (see above)

Kundasala Engineers Sri Lanka (see above)

Packaging and labelling machines

Acufil Machines India (See above)

Gardners Corporation India (see above)

Gurdeep Packaging Machines Harichand Mill compound LBS Marg, Vikhroli Mumbai 400 079 India Tel: +91 22 2578 3521/577 5846/579 Fax: +91 22 2577 2846

MMM Buxabhoy & Co 140 Sarang Street 1st Floor, Near Crawford Market Mumbai India Tel: +91 22 2344 2902 Fax: +91 22 2345 2532 Email:;;

Narangs Corporation India (see above)

Orbit Equipments Pvt Ltd 175 - B, Plassy Lane Bowenpally Secunderabad - 500011,Andhra Pradesh India Tel: +91 40 32504222 Fax: +91 40 27742638 Website:

Alvan Blanch UK (see above)

C S Bell Co 170 West Davis Street PO Box 291 Tiffin Ohio 44883 USA Tel: +1 419 448 0791 Fax: +1 419 448 1203

Pharmaco Machines Unit No. 4, S.No.25 A Opp Savali Dhaba, Nr.Indo-Max Nanded Phata, Off Sinhagad Rd. Pune – 411041 India Tel: +91 20 65706009 Fax: +91 20 24393377

Rank and Company India (see above)

Banyong Engineering 94 Moo 4 Sukhaphibaon No 2 Rd Industrial Estate Bangchan Bankapi Thailand Tel: +66 2 5179215-9

Technology and Equipment Development Centre (LIDUTA) 360 Bis Ben Van Don St District 4 Ho Chi Minh City Vietnam Tel: +84 8 940 0906 Fax: +84 8 940 0906

John Kojo Arthur University of Science and Technology Kumasi Ghana

Alvan Blanch UK (see above)

KOS Industrial Emulsifying Equipment A18 Second Floor, Building 1, Shunlian Machinery Plaza, ChenCun Town Foshan China Tel: +86 0757 29318541 Website:

Contacts[edit | edit source]

The following contacts should be able to provide further information:

Indian Institute of Spices Research (IISR) Marikunnu PO, Calicut Kerala India 673012 Tel: +91 495 2731346 +91 495 2730294 Email:; Website:

Indian Institute of Technology (IIT) Bombay Powai Mumbai 400076 India Tel: +91 22 2572 2545 Fax: +91 22 2572 3480 Website:

Further reading[edit | edit source]

Practical Action Technical Brief – Drying Practical Action Technical Brief – Spice processing Practical Action Technical Brief – Labeling food products FAO InPHO Indian Spices

Practical Action The Schumacher Centre for Technology and Development Bourton-on-Dunsmore Rugby, Warwickshire, CV23 9QZ United Kingdom Tel: +44 (0)1926 634400 Fax: +44 (0)1926 634401 E-mail: Website: This document was produced by Dr. S. Azam Ali for Practical Action in March 2007. Dr. S. Azam-Ali is a consultant in food processing and nutrition with over 15 years experience of working with small-scale processors in developing countries.

External links[edit | edit source]

FA info icon.svg Angle down icon.svg Page data
Part of Practical Action Technical Briefs
Keywords turmeric, spices
Authors Fatima Hashmi
License CC-BY-SA-3.0
Organizations Practical Action
Ported from (original)
Language English (en)
Translations Indonesian
Related 1 subpages, 6 pages link here
Aliases Tumeric
Impact 13,246 page views
Created April 16, 2008 by Fatima Hashmi
Modified February 28, 2024 by Felipe Schenone
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