Processing Paddy Rice: Parboiling and Milling
       
  What is the parboiling process and how does it affect rice?  
  Describe the parboiling process, its advantages and disadvantages, and list the physical, chemical, and aesthetic changes that occur during this process.  
     
Three steps in the parboiling process
 

Parboiling is the hydrothermal treatment of paddy before milling. The three steps of parboiling are:

  1. Soaking (sometimes called steeping) paddy in water to increase its moisture content to about 30%.
  2. Heat-treating wet paddy, usually by steaming, to complete the physical-chemical changes.
  3. Drying paddy to a safe moisture level for milling.

Click each of the steps below to learn more about the processes associated with each.

  
   
Changes caused by parboiling
 

Parboiling causes physical and chemical changes and modifies the appearance of rice. To learn more about these changes, click through the pages of the following flipbook.

  
   

    These changes affect the results obtained during milling, storage, and cooking and ultimately, consumer preference. Click here to view a table that compares brown rice and milled rice before and after parboiling.

  
  Click here to view an exercise which will allow you to compare and contrast the characteristics of parboiled and raw rice.

  
Advantages and disadvantages of parboiling
  

Consumer preference will prevail despite the advantages and disadvantages associated with parboiling. Nevertheless, the following table provides a balanced view:

During... Advantages Disadvantages
Milling

• Dehusking is easier and costs less
• Fewer brokens
• Increased head and total rice output

• Bran removal is more difficult and costs more
• Cannot be used in starch-making or brewing industry
• Doubles the total processing cost
Storage More resistant to insect attack Becomes rancid more easily
Cooking Loses less starch and keeps longer Takes longer to cook and uses more fuel


 
Next lesson
   In the next lesson, you will learn about different parboiling methods.