Improved Parboiling Methods in India

PRESENTED BY: RUATFELA DARLONG

M Tech (16AG63R16)

DEPARTMENT OF AGRICULTURAL AND FOOD ENGINEERINGINDIAN INSTITUTE OF TECHNOLOGY KHARAGPUR

Contents

ParboilingAdvantages of ParboilingDisadvantages of ParboilingParboiling methodsCFTRI Method Jadavpur University ProcessDandekar Process Indus ProcessRPEC Method, IIT KharagpurPressure Parboiling MethodReferences

Parboiling:Parboiling involves a hydrothermal treatment by soaking, steaming and drying before milling.

Paddy parboiling originated in India. It is now widely used all over the world.

Advantages:• Improvement in quality due to high head rice and fewer

broken grains.• The milled rice becomes translucent and shining.• Resistant to insect attacks.•Grains are firmer and less likely to become sticky after

cooking.• Parboiled rice retains more proteins, vitamins and minerals.• Parboiled rice is more digestible.

Disadvantages:

•Heat treatment during parboiling destroys some natural anti-oxidants, hence rancidity may develop more in parboiled rice than in raw rice.

• It takes more time to cook, usually double of raw rice.

• Parboiling needs extra capital investment and extra power requirement.

Parboiling methods:• Traditional methods: Atapa, Balam, Sela, Siddha (India).

•Modern methods: CFTRI method, Jadavpur University Method, Dandekar Process, Induss Process, RPEC Process, Pressure Parboiling Method.

Schule Process, Avorio Process,Cristallo Process, Malek Process,Rice growers association of California Process.

Improved Indian Parboiling methods: • Even in modern technology, the two main elements for gelatinizing starch in the

grain are still water and steam.

• An average of 600 liters of water is needed to steep (soak) 1 tonne of paddy. During steeping, about 20% of the water is absorbed by the paddy.

• In modern plant, about 80 kg of steam is considered necessary to heat 1 kg of paddy.

• Modern plants may be divided into two types, viz. a continuous or batch-type.

A. CFTRI Method, Mysore:Objective: The main aims of this parboiling systems are to improve the quality of rice, shorten processing time, lower equipment costs and simplify operation.Process: Parboiling tanks are filled with clean water and heated to 85°C (by passing steam through coils and placed inside the tank). Paddy is poured manually into the steeping and steaming tank. Resultant temperature of mixture in the tank stays around 70°C. Soaking is done for 3 hours, and water is drained out. Soaked paddy is exposed to steam at a pressure of about 4 kg/cm2. Soaking and steaming of paddy are done in the same tank. The parboiled paddy is evacuated through bottom hatch and dried either under sun or by mechanical drier.

B. Jadavpur University process:

•All the operations of this method is fully automatic and average processing time is 5 to 6 hours.•Soaking at 60°-70° C.•Steaming for 3 to 5 minutes.•Rapidly cooled the steamed paddy.•Drying in a rotary steam jacketed high temperature air drier.

C. Dandekar Process:

The Dandekar process was developed by one of the leading Indian manufacturers of rice processing machinery. The system is similar to that developed by CFTRI, where steeping and steaming is done in an open tank. Since the tank has no top, steaming of the paddy is performed at atmospheric pressure. Hot air is generated by means of a steam heat exchanger. Parboiled rice obtained is dark in color but translucent and of good quality.

D. Induss Process:

Induss is the name of the plant manufacturers based in Calcutta. Their process differs only slightly from that of CFTRI. Here, the grain is first cleaned and then fed into a metering bin. It is then discharged into the steeping tank. The water is fed into the parboiling tank from the lower side by a high pressure pump. After steaming, drying takes place in a vertical column drier.

E. RPEC Method:

This method was developed by Rice Process Engineering Centre at Indian Institute of Technology, Kharagpur during 1970-73. The paddy is soaked in water at or a little above the gelatinization temperature. No steaming is required. The main advantage is that the boiler can be eliminated as no steaming is required in the process.

F. Pressure Parboiling Method:

Developed at Tiruvarur in Tamil Nadu, the paddy is soaked initially for 40 minutes at 85°-90°C. Thereafter, it is steamed under pressure for 18 minutes. The whole process is completed in 60 to 90 minutes. Reduced soaking period of paddy is the main advantage of this method.

References:

•Sahay K.M, and Singh K.K., 2004. “Unit Operations in Agricultural Processing”, Vikas Publishing House Pvt. Limited. ISBN 8125911421, 9788125911425.

•F. Gariboldi, 1984. “Rice Parboiling”, Issue 56, Food and Agricultural Organization. ISBN 9251014000, 9789251014004.