Processing of turmeric by traditional way

Post Harvest Management

In India, at various places different post harvest management and equipments are used, but basic method is mentioned below in a process

Washing

At first rhizomes are detached after digging out from the soil and these are washed away, so that elements of soil, spray residues and unuseful particles attached with the rhizomes are removed. For this rhizomes are preserved soaked in water all over the night. Later on rhizomes are removed out and water is sprayed. This process can be achieved by soaking and spraying equipment. Spraying is made at low pressure and extensive angle jet or with high pressure jet. At the period of washing rhizomes are divided in two parts. First part from middle is called mother rhizomes. The second portion of it which is extensive and thin is called Doctor Rhizome. Mother rhizome is kept for seed while Doctor rhizomes are further processed and sold.

Boiling/Blanching/Cooking

The succeeding step of processing is boiling or blanching. Conventionally boiling is done in metallic or mud pots along with ¾ water. Top of the pots are covered with a lid or dry leaves. Boiling process is continued till foams and white foams begin coming out. These come out with a unique quality of taste. Rhizomes are tested by pressing with fingers. If rhizomes are soft and inner colour has become yellow instead of red then this procedure is said to be completed.

By using developed method of boiling or blanching both colour and quality are improved. Time taken is less. In the developed technique bulbs are treated with 0.1% Soda (Sodium Carbonate, Ammonium Carbonate or Sodium bicarbonate) and water solution. The time required for this process is 30 minutes to 6 hours. Boiler is used in the developed technique which is metallic kettle open from the top. Soda solution is filled in it and it is heated from the bottom by electric heater or fuel oil. Perforated frame loaded with turmeric tubers or bulbs are sunk at this time. Water from every side of perforations arrives inside making turmeric tubers soft. After 30 or 40 minutes bulbs/tubers are taken up and tested alongwith the frame.

Drying

Cooked rhizomes are cooled first and spread slowly in the yard for drying. It takes at least 10 to 15 days for drying in the sun. Tubers are brought up and down in the middle of ventilating so that all are dried well. Mother rhizome takes moderately more time while Doctor Rhizome dries up quickly. Therefore this are dried distinctly also. After drying these become firm and solid. Totally dried turmeric holds 6% moisture content in post harvest management.

Polishing

Dried rhizomes are rubbed against ground or below the foot to take out the hard layer over them and small roots are separated. By this procedure colour of turmeric develops bright or shining. Later on removed roots, light garbage and thin layerings are cleaned.

Machine is also used for polishing in  post harvest management. For this a drum having 0.9m diameter and 0.6m length is used. It is kept horizontally on a shaft and operated by a handle. Average capacity of this device comes to 32 kg per batch. Dry turmeric 32 kg approx.is occupied and polishing is made at least for 7 minutes. During this time water is also sprinkled which causes improvement in the colour of turmeric.

Colouring

Exporting turmeric is given special colour by combining yellow so that powder and processed ingredients can give better look and quality. Cleaning is done by two ways. One is dry colouring and the other one is wet colouring. In the first procedure dry powder of yellow colour is drenched on boiled turmeric and rightly mixed. Powder is known as middle crome. In the wet colouring process its solution is made in water which is drenched on rhizomes and mechanically mixed. After colouring is complete for one week these are dried. Later on these rhizomes are preserved in sacks and closed for transferring.

Grinding or Powder making

Traditionally dried and polished turmeric are cut into pieces and beaten in mortar and pestle. Afterwards this is crushed or ground with hand operated chakki. Hammer mill is also used for grinding. Powder should be so fine that it passes through 300 micron sieve and nothing is left over the sieve.