ricepolisher's blog

The design concept of the rice whitener is the result of the accumulation of many years of vertical milling engineering expertise. This machine has incorporated all of the most modern techniques of vertical milling and has been proven to be "The Machine" in many major mills throughout the United States and Europe, and in Asian countries such as Thailand and India. The versatility for milling all degrees of milled rice has given the industry the ideal machine.

Two important qualitative indices, degree of milling and percentage of broken kernels, were considered as input variables and the level of pressure on the discharge section of the whitening machine was selected as the output variable in the fuzzy inference unit. Results of the evaluations indicated that the developed ACS had 89.2% accuracy in determining the desired working conditions for the whitening machine.

The abrasive rolls are easily withdrawn out of the top of the unit, because the cantilever main shaft design makes a bearing at the top of the machine unnecessary. The screens are of a 'lift away design' which makes screen changes quick and easy and can be performed without having to remove the frame from the machine. All other parts are easily accessible and readily interchangeable. 

rice destoner is used to remove the epidermis (aleuron) on brown rice to produce white rice that is ready to be marketed or cooked. This machine uses the screw extruder system in the cylinder which has the inner surface uneven. When brown rice fed into the cylinder it will jostle and rub against the cylinder surface which causes the epidermis to be eroded.

Threshing delays can cause grain yellowing due to stack burning, mold growth in heated piles, and mycotoxin. A 1-day threshing delay of cut crop in a conical pile (mandala) and small rectangular piles resulted in 17% and 5% yellow grains, respectively, whereas a 5-day delay resulted in 68% and 40% yellowing of grains in the mandala and small rectangular piles, respectively. Delayed drying of wet grains results in stack burning due to non-enzymatic browning, microbial growth, and mycotoxin production in parboiled rice. In another study, 100% yellowing of the grain was noted in wet paddy with more than 20% MC. Mold growth and heating of the grains were noted. Heating of the heap occurred within 1 day, mold growth was visible after 2 days, and yellowing of the grains happened within 5 days. Paddy threshed and dried to 14% MC immediately in paddy husker after harvest yielded < 1% yellow grains.

Rough rice drying plays an important role in post-harvest practices. Excessive losses can be avoided if drying had conducted properly. Head rice yield (HRY) is a commonly accepted standard for measuring rice milling quality. After harvesting, in major rice producing regions of Iran, there would be delayed rough rice drying and milling due to great deals of produced paddy and low capacity of rice milling plants. This research aimed to investigate the effect of various drying dates on milling recovery head rice yield. The experiments were conducted on five different dates of 0, 15, 30, 60, and 90 days after harvesting and two long grain cultivars of Hashemi (local) and Khazar (improved). The results revealed that cultivars and drying dates had significant (p<0.01) effects on head rice yield. Head rice yield for Hashemi had a decreasing trend under delayed drying dates whereas there was not such a circumstance for Khazar.


It is observed that in conventional paddy separator operating cost of using husk and coal is less than auto paddy separator. But capacity and economical profit comes more in auto rice mill. Through comparative study it is found that the efficiency of using both husk and coal comes out to be the same, but their comparison varies when discussed about economic and expenditure of plant. It is seen that the price / day of using husk is more than that of coal which implies that husk used as fuel is more beneficial than using coal as fuel. When both the fuels are compared i.e. husk and coal then, it is concluded that husk as fuel is used free of cost but coal much maintenance requires which leads it to have more cost in comparison to husk and also pollution created by coal is more than that of husk, which makes husk more reliable than the coal.

paddy husker consists of a series of processing stages including the soaking, steaming, and drying of paddy rice grains. The parboiling process has resulted in increased milling yield and enhanced nutritional value and resistance to spoilage. The major advantages of the parboiling method include rice starch gelatinization and hardening of the rice kernels, which reduces endosperm germination and breakage losses during milling. Researchers have used a variety of techniques to parboil rice.

Unnikrishnan and Bhattacharya described pressure parboiling as low moisture parboiling in which the rice paddy is partially soaked or simply washed with water and then steamed at high pressure to gelatinize the rice starch. Walter et al. used conventional and laboratory steaming methods in which rough rice was placed at 1.5 kg/cm2 for 25 minutes, or, in the laboratory method, rough rice was steamed at ambient pressure for 20 minutes using an autoclave. The effectiveness of the steaming process depends on the steam conditions (either saturated in an open system or superheated in a closed system), steam pressure, and steaming time.

The dehuller consists of rotary cylindrical sieve which separates the chaff from the rice grains via the shaft and blade. Impact method was adopted for the removal of husk from the rice paddy. After milling the paddy rice, it passes through a vibrating sieve machine where a crank mechanism converts rotary motion into a reciprocating movement of the sieve bed. The vibrating sieve removes the chaffs and the pebbles from the rice grains.

Quality parameters like whiteness and HRY after rice whitener should be estimated from two dimensional image while the correlation mean gray level have been reported with the lipid concentration on the surface of rice kernels (Fant et al.,1994). It was hypothesized that the overall whiteness of milled rice could be estimated simply from the mean value of the gray level distribution obtained from the digitized image of the bulk sample. Digital image analysis has been used to estimate the area of the bran layer on the surface of rice kernels and correlated with the surface lipids concentration determined by chemical analysis (Liu et al.,1998).

rice grader is necessary in the development of quality standards that define the relationship between grades and prices in the assessment of the value of grains. Official standards are important in the marketing process because they furnish the means of describing variations in quality and condition. They also provide a basis for merchandising contracts, for quoting prices, for loans on product in storage and for sorting and blending by producers to meet market requirements. Grading then provides for an orderly marketing and trading system.

Hedonic pricing analysis is conducted to determine the implicit values of various attributes in the market value of a good. In this study, hedonic pricing analysis was applied to measure the contribution of grain quality search and experience attributes to the price of rice in two rural towns in the Philippines. Rice samples from respondents underwent quantitative routine assessments of grain quality. In particular, gelatinization temperature and chalkiness, two parameters that are normally assessed through visual scores, were evaluated by purely quantitative means (differential scanning calorimetry and by digital image analysis).

The operator, based on his experience and proficiency with the processing machinery, assesses the quality grade of the product by mere visual inspection of the machine output and making the required adjustments. Most of the time, this operation is neither carried out with enough accuracy nor performed in a short time. In this regard, development of automated systems which can work based on the operators' expertise may be an efficacious method for fast and reliable quality grading of the product.

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To be able to meet the above requirements, the separation process must include sieving, cleaning, winnowing, screening and the use of aspiration machine. Literature has shown the existence of paddy cleaner which works on a principle that makes use of the densities variation between sand and rice. There is another specific gravity separation method adopted by Adekoya and Koya (1994). The system involves movement of grains on an oscillating conveyor and the application of aerodynamic force.

Another machine for the separation of dust and stone from rice is the stoner separator. Multi crop cleaner has been developed by Ademosun (1993). Ozormba described rice destoner as a machine, which takes advantage of the difference in axial velocities of rice and stone. The rice is fed via a hopper into a rotating cylindrical sieve, which separate the rice from the stone. The rice passes through the sieve and leaves the stone in the cylinder to roll down to the stone collector while rice is being collected in the rice collector in his paper used sieve shaker to separate guinea corn from rice. A method of separation similar to this is adopted in the current research work.

Poorly conceived ventilation of grain storage can result in further problems. If humid air is blown into dry grain in storage after paddy separator, for example, moisture will develop, building up significantly when the air temperature is higher than the grain temperature. Therefore, a well moderated airflow is important to extend storage time and hence market flexibility. Different areas of the world are experiencing their own unique trends, such as in Australia, where a current major design element is for sealed fumigation grain storage. The nation is also experiencing expansion in its container packing facilities in order to utilize the large number of containers that leave the country for high demand in Southeast Asia.

A combined knowledge of the physical properties and anatomical composition of the rice grain is a prerequisite in gaining a closer understanding of what happens to the grain in the different postharvest operations. The understanding of the anatomy of the rice grain will clarify the reasons why rice kernels break so easily on mechanical impact during the physical operations of threshing and milling, and under thermal stress during drying. methods on the surface tissue of the grain kernel and the kernel itself, will indicate the importance of the correct adjustment of rice polisher in order to prevent breakage, and ensure higher milling recovery.

Rice mill effluent contains high concentration of organic and inorganic substances leading to significant source of pollution. The effluent has high Biological oxygen demand (BOD), Chemical oxygen demand (COD), and Total Dissolved solid (TDS). The major advantage of electrocoagulation is that it avoids the usage of any chemicals and so there is no need for neutralizing agents. The effective performance of this technique in the treatment of rice mill wastewater has been investigated using a combination of aluminum and iron electrodes. After the treatment, BOD, COD, and dissolved solids were sufficiently reduced. In addition, it was found that an increase in the current density enhanced the speed of the treatment significantly and the Fe-Fe electrode combination gave the highest removal efficiency.


Cleaned paddy demands a higher price than non-cleaned paddy-an incentive for cleaning the paddy by paddy cleaner. In contrast, lack of cleaning often results in a higher concentration of contaminants in the milled rice. Another consideration is that stones and other hard particles shorten the life of the milling equipment. Finally, milling recovery is low when paddy is not cleaned (Lantin, 1997).

Grain or rice grader inside and around grain facilities can be a source of infestation by various stored grain pests, which find shelter in cracks and crevices. Insect damage can result in reduced grain weight, loss of nutrients and decreased germination. It can also cause a deterioration and contamination to the grain, which results in a poorer grade of grain and lower market value.

More than 40 million hundredweights of rice are produced in California's Sacramento Valley every year. After harvest, the rice is stored in facilities on-farm or off-farm until it is transported to mills or to ports for export. We conducted a survey of storage operations to characterize grain storage and pest management practices to guide future UC Cooperative Extension research efforts. The results indicate that grain moisture content, temperature and insect pest management are the most important challenges for both on- and off-farm storage operations. Survey responses show high adoption of integrated pest management programs, with most storage operations relying on monitoring, thresholds, sanitation and aeration to manage pest problems. Fumigant use was reported more frequently in off-farm storage operations than on-farm operations. Cooperative Extension educational efforts should focus on grain and temperature monitoring, insect identification and safe use of fumigants. Research is needed to improve management of grain temperature and moisture content, and insect infestations.

In the milling process, the higher milling degree indicates a greater percentage of bran removed. The degree of milling as determined by the quantity of the outer layer removed from the brown rice kernels. When rice is fully milled the vitamins (a complex), protein, mineral, and oil contents are lessened. This explains why persons with beri-beri (Vitamin A deficiency) are advised to eat brown rice. This also probably explains why persons who eat well milled rice are prone to be protein difficient or even malnourished. Thus, it is not surprising that some dieticians recommend the eating of regularly milled or even undermilled rice.

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