Introduction
Parboiled rice, also called “half-cooked rice,” is a nutritious type of rice made from paddy rice. It goes through cleaning, soaking, steaming, drying, and then milling. It has a light yellow or golden yellow color and a chewy texture. Its price is 5%-10% higher than regular rice. This article will guide you into the relevant content of parboiled rice.
Production process
As mentioned earlier, the production process of parboiled rice takes several more steps than that of white rice. Below I will introduce the production process of it to you one by one.
Paddy cleaning
First is cleaning. Before any processing, you must clean the paddy rice to ensure the quality of the rice and the smooth operation of the process. The cleaning stage mainly removes weeds, straws, dust, and large impurities. A cylindrical pre-cleaner and a vibrating cleaner are usually used. For paddy rice used to make half-cooked rice, removing dust is very important. This helps prevent dust contamination during the soaking stage.
Soaking
The second step is soaking. Using vacuum, constant temperature, and pressure soaking, the paddy rice quickly absorbs water. During this process, the nutrients from the husk are fully absorbed by the rice grains.
The soaking tank is made of stainless steel and can hold 6 tons of paddy rice and 5000L of water. Depending on the variety and quality of the paddy rice, the soaking temperature is set between 65-72°C, and the soaking time is 6-8 hours. The purpose of soaking is to increase the moisture content of the paddy rice to 40%. This is necessary for starch pre-gelatinization. Otherwise, the rice will not be fully cooked during the steaming stage, affecting its quality.
Steaming
The steaming process is actually the process of starch gelatinization. It helps change the physical structure of rice, kills insect eggs, preserves nutrients, and extends storage time. During steaming, you must strictly control the uniformity of high-temperature and high-pressure steam in both temperature and time. This ensures that the starch in the paddy rice is fully but not excessively gelatinized.
When starch is fully gelatinized, the cooked rice appears transparent with a honey-like color. This happens because pigments from the husk and bran move to the rice core, and a browning reaction occurs during pre-cooking. By adjusting the steaming parameters, you can produce light-colored, medium-colored, or dark-colored rice. Steaming has a significant impact on the final product’s quality, color, texture, grain strength, milling yield, and storage characteristics.
Drying
The drying process has two stages.
The first stage is rapid drying using a fluidized bed. The steamed paddy rice is discharged from the water tank and enters the fluidized bed through a belt conveyor or bucket elevator. It undergoes rapid drying for about 2 to 3 minutes, reducing the moisture content from 40% to 26%.
Next, the rice enters a low-temperature, slow-cycle dryer. It dries at a temperature below 80°C for 12 hours, reducing the moisture content to a safe level of 14%. This makes the rice easier to store, process, and mill. This process helps reduce the breakage rate and improve the whole kernel yield.
Cooling
The dried paddy rice is still very hot and cannot be hulled immediately. It must be cooled before processing. The paddy rice is sent to a vertical cylindrical silo for temporary storage. Inside the silo, ventilation fans remove excess heat and help distribute moisture evenly in the rice.
Paddy husking
Once the paddy rice has naturally cooled, it can go through the milling process. Aside from the earlier necessary processing steps, the following milling process is almost the same as for white rice.
After cooling, the paddy rice enters the rice hulling machine. The rubber rollers squeeze and rub the rice to remove the husk, preparing it for further milling.
Paddy separating
The mixture of hulled rice and unhulled paddy enters the paddy separator. The separator moves at an angle and uses different sieve hole sizes to separate brown rice, mixed rice, and paddy.
The brown rice moves to the next milling stage. The mixed rice goes through another separation process. The unhulled paddy returns to the hulling machine for re-hulling.
Whitening
The whitening stage removes the bran layer and further polishes the rice.
There are two types of rice milling machines: iron roller and sand roller rice whitening machines. The iron roller milling machine has a lower speed and provides more even milling, making it better for grains with high oil content. Since parboiled rice is more oily and tough, we prefer using an iron roller milling machine to process it.
Grading
After milling, the rice will usually have some broken rice, so we also need to grade the rice.
The rice grader uses a series of screens with progressively smaller holes from top to bottom to separate the rice. It sorts the rice into whole kernels, large broken, medium broken, and small broken, making it easier for you to handle them differently.
Color sorting
After grading the rice, the whole kernels go into a color sorter. The color sorter uses photoelectric technology to precisely remove any off-colored grains, further helping you improve the quality of the rice.
Rice polishing
After color sorting, the rice undergoes a rice polishing machine to further improve its shine. Polishing enhances the appearance of the rice. It is actually a starch gelatinization process that helps fill in any cracks on the rice surface, making it glossy and translucent. This improves its commercial value and storage performance.
Rice packing
The processed rice is packed using a packing machine. You can set the weight for each bag on the control panel, and the packing machine will measure it precisely, saving time and effort.
This is the entire processing flow of parboiled rice. So, if you want to process it, you need to have both milling equipment and a full set of parboiled rice processing equipment. These two must be used together.
Parboiled rice advantages
Good Nutrition
First, parboiled rice is highly nutritious. Regular white rice goes through multiple processes that remove the nutrient-rich husk and germ, leaving less than 5% of the nutrients. Parboiled rice, on the other hand, undergoes hydrothermal treatment on unhulled paddy rice. This process allows soluble vitamins and minerals from the husk and bran to seep into the endosperm, preserving the germ. It also optimizes the starch structure, lowers the glycemic index, and retains more than 87% of its nutrients. Experts agree it is especially suitable for diabetic patients.
Less broken rice
Parboiled rice has firm grains and strong toughness, making it less likely to break. During processing, it produces fewer broken grains compared to regular rice, which helps reduce rice loss to some extent.
Easy cooking
Parboiled rice is partially cooked because it has already been steamed, so it cooks faster than traditional rice. It has a strong aroma, and the cooked rice is soft and non-stick. The yield is 37-76% higher than that of white rice of the same quality.
Longer storage time
Since the rice is steamed during processing, the high temperature kills pests, inactivates the rice enzymes, and removes its ability to sprout, which extends its shelf life. This characteristic also makes it suitable for transportation under certain conditions.
Market demand
The market for parboiled rice is focused in Europe, the Americas, the Middle East, and some countries in Central and South America. It is known as a healthy rice and green food. It is more expensive than regular rice and is internationally recognized as a low-GI healthy rice. So parboiled rice is suitable for people with diabetes and high blood sugar to consume.
How do you choose your parboiled rice mill plant?
Production demand
First, you need to determine your output. Based on how much rice you want to produce per hour, you can decide the production capacity of the line. Since each machine has different output options, by determining your production needs, we can match you with the right production line.
Automation degree
Next is the level of automation. Our parboiled rice processing line is fully automated, requiring no manual operation. The machines handle feeding, discharging, and temperature control automatically, saving labor while ensuring precision. If you choose a line with lower automation, the experience of the operators becomes crucial, and staff training will also be an additional cost.
Production process and equipment
Finally, you need to consider the processing technology and equipment. The key to making parboiled rice lies in the steaming process. Our production line separates soaking and steaming, improving steaming quality. In the drying stage, we use fluidized bed rapid drying and a low-temperature, slow-cycle dryer. This not only shortens the drying time but also ensures even drying. As a result, the final product has no cracks and a low breakage rate.
Conclusion
I believe that after reading this article, you have gained a certain understanding of parboiled rice. As an internationally recognized nutritious rice, of course, it has a promising market and profit potential. ANON has a professional team dedicated to providing simple and efficient machines for your business. ANON, operate easy, harvest more!
FAQ
2. Why does parboiled rice taste different?
First, it isn’t actually a different type of grain, but rather, it gets its name and different flavor from the process of partially boiling it in its husk.
