All the food grains i.e. Cereals, pulses, oilseeds, nuts etc. go through number of processing operations such as cleaning, grading, separation, drying, storage, milling etc. before we consume it.
The first and important operation in grain processing is cleaning. Cleaning is performed to remove unwanted materials from grains. Sometimes drying of grain mass can be performed before cleaning to remove excess moisture due to early harvesting of grains.
What is cleaning?
In cleaning process, other undesirable materials such as other seeds/grains, damaged grains, weed seeds, clay/stone particles from field etc. are removed manually by handpicking or by using different sieves. Cleaning of grains is also performed by using power operated grain cleaners. Grain cleaners are capable to clean large grain mass in short time.
Another terms associated with cleaning are grading, sorting and washing.
What is grading?
Grading operation is done to separate the cleaned grains into various quality fractions depending on commercial use. Grain quality is important from field to consumer. Grains can be graded according to size, moisture present, appearance, color, quantity of foreign material/broken grains present, chemical composition etc. On basis of such usage, grains can graded in different grades.
The grain processor or manufacturer of any food can ask for specific quality grains according to his needs to develop specific product to cater consumer’s demand.
Grader equipment is used for grading of grains, which separate the entire grain mass according to size, shape etc. Various grader machines suitable to different grains can be used to grade the grains into different fractions.
What is sorting?
Sorting refers the separation of cleaned grains into various quality fraction according to size, shape, density, texture etc. In case of sorting based on size, well sorted grains have similar size whereas poorly sorted grains have varying sizes.
Different grains possesses different characters and sorter machine can be used to sort grains. Color sorter machines are also used to sort the grains according to color of grains. Color sorters separate the grains by their colors.
For example Rice sortex machine separate the stones, damaged rice grains on basis of color difference. Color sorters can also used to sort coarse cereals such as wheat, corn, peanut; pulses; oilseeds; coffee beans and nuts. To know more about optical sorting read: More about grain sorting
Watch video: Working of optical sorter