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The parboiling rice process plays a crucial role in rice production by offering significant economic benefits such as improved rice yield and reduced grain breakage during the milling operation.
There are four kinds of parboiling methods, each contributing distinct rice characteristics and textures. The key difference between these techniques lies in the time-temperature combinations used during the soaking and steaming stages.
With that in mind, now let’s take a closer look at each stage in detail.
Types of parboiling rice process
Sella process
First comes sella process, Let’s breakdown each step below:
● Kachi Tank Pre-Steaming:
Once the paddy is de-stoned and cleaned, the system feeds it from the storage bin into the Kachi tank for pre-steaming. There, the grains steam sufficiently, ensuring they gelatinize upon subsequent heating at 3-bar pressure.
This pre-steaming operation reduces the soaking time of the paddy and increases the capacity of the rice to absorb water during cooking.
● Soaking:
The steamed paddy then absorbs water for moisture saturation and generalization.
● Pakki Steaming System:
The process drains the soaked paddy before transferring it for final steaming at 3-bar pressure.
● Tapered V Dryer:
The specialized drying mechanism reduces the paddy’s moisture content from approximately 36% to 12% through evaporation.
● Transported to Rice Mill:
The system cools down the processed paddy to room temperature before transporting it to the rice milling area for final rice production.
Boiled Rice Process
Boiled or parboiled rice involves full gelatinisation of grain. Here are the detailed steps:
● Soaking:
In this process, the cleaned paddy is first soaked and circulated in hot water at 70 degrees Celsius.
● Online Cooker:
The soaked paddy is lifted by an automated conveyor system and enters an online cooker, where high-pressure steaming at 3 bars enhances gelatinization.
● Tapered V Dryer:
The specialized drying mechanism reduces the paddy’s moisture content from approximately 36% to 12% through evaporation.
● Transported to Rice mill:
The system cools the processed paddy to room temperature before transporting it to the rice milling area for final rice production.
Half-Parboiled Rice Process
This process concentrates on Half-gelatinisation of rice which takes less steaming period than bolied rice.
● Soaking:
In the half-boiled rice process, the cleaned paddy is soaked and circulated in cold water at ambient temperatures to increase the moisture content and enhance the gelatinization of kernel.
● Online Cooker:
The paddy is mechanically elevated by an automated conveyor system and fed into an online cooker, where the soaked paddy undergoes continuous steaming at 0.8 – 2 bar pressure.
● Tapered V Dryer:
The paddy is dried using a specialized drying mechanism to evaporate moisture content from approximately 36% to 12%.
● Transported to Rice mill:
The processed paddy is then cooled down to room temperature and transported to the rice milling area for final rice production.
Steamed Rice Process
This method accelerates the aging of rice using the curing process:
● First-pass Drying:
In this process, the paddy is directly fed into the dryer system, where the moisture content is brought down to 18%-20%.
● Online Cooker:
The dried paddy is fed into an online cooker for final steaming at 0.8 – 1.5 bar pressure.
● Second-pass Drying:
The steamed paddy is again dried to reduce the moisture content from 32% to 12%.
● Transported to Rice mill::
The system cools the processed paddy to room temperature and then transports it to the rice milling area for final rice production.
Conclusion
Each of these parboiling techniques follows a unique combination of soaking, steaming, and drying. Carefully monitoring temperature and pressure at each stage will ensure better texture, nutritional retention, and market value. For more information on paddy parboiling plants you can check our products here.
FAQ
Q1: What is the main purpose of parboiling process?
A: To reduce grain breakage and increase the total rice yield, the milling process optimizes operational techniques.
Q2: Can all types of rice be processed in a paddy parboiling plant?
A: Yes, but operators may adjust or specialize the machinery for different rice varieties.
Q3: What happens to the by-products of rice processing?
A: Husks can be used for energy, bran for oil, and broken rice for animal feed or brewing.
Q4: Is there an environmental impact from paddy processing plant operations?
A: There can be; proper waste management and energy-efficient machinery reduce this impact.
