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More efficient heating with microwaves

When producing fast cooking rice, microwave technology saves energy, time and money.

Challenge in terms of sustainability:

In terms of economic and ecologic sustainability, both time for production process as well as especially energy effort should be minimized when producing parboiled rice, fast cooking rice or instant rice.

Initial situation:

Conventional methods are time-consuming and energy intensive processes: First of all, the unpeeled rice is watered. After that, the surplus water is removed mechanically and the rice is left to rest for a while in order to achieve an equal moisture distribution. Afterwards, the rice is heated, mostly by conventional cooking. Finally, the rice is dried and packed.

The solution:

"Process and apparatus for the production of short cooking time rice (Patent WO 03/073867)"
The advantage of microwave technology compared to many other heating methods is that microwaves can penetrate products so that the heat inside the product is released. That way, long heating and treating times can be avoided. In the newly developed process, the rice firstly is peeled and then directly packed in a cooking bag. Afterwards, it is heated by microwaves without adding water. The natural residual moisture of app. 14 % which is contained in the rice produces when being heated a steam atmosphere inside the cooking bag in which pre-cooks the rice. After microwave treating, the rice is only cooled down and packed in a carton.

The sustainable advantages:

The new method makes superfluous the soaking for several hours and time-consuming drying. Consequence: enormous time saving up to 90 %.
Moreover, energy consumption is considerably lower – up to 70 % as especially the energy intensive drying process is omitted.
It was determined by the results of the X-ray diffraction analysis that the transformation rate of the crystalline phase of rice starch in amorphous form is higher in case of traditional pre-cooking than in case of microwave treatment (in this case, transformation rate is only 10-15 %).
Conclusion: The new method enables a more efficient and faster production and thus reduces the costs for producing fast cooking rice.


The new method was developed by Linn High Therm GmbH (Germany) and AboMill (Hungary) in collaboration with the Research Institute for technical chemistry, Veszprem (Hungary).
Mr. Horst Linn – president of Linn High Therm GmbH – engages himself in this subject for many years how to optimize production processes by microwave technology. He wrote numerous publications concerning this subject and is a popular speaker on international process engineering conferences.

Brief profile of the company:

Name: Linn High Therm GmbH
Headquarters: Eschenfelden
Year of foundation: 1969
Employees: app. 100
Solutions: electrically heated industry and laboratory furnaces, inductive melting and casting units as well as induction heating units, microwaves and vacuum furnaces
Internationality: service- and sales network in more than 50 countries all over the world