Harvesting the millet from the field is not only the end of millet farming but also the start of processing to add extra value to the product for the end users. Processing of millet entails several processes, each needing specialized equipment. India cultivates nine types of millet, divided into two categories based on whether the grains have a husk or not:
- Husked Millets: Foxtail millet, Little millet, Barnyard millet, Proso millet, Kodo millet, and Browntop millet. These must be dehulled before consumption.
- Naked Millets: Sorghum (Jowar), Pearl millet (Bajra), and Finger millet (Ragi) do not need dehulling.
Processing Small Millets: Common Challenges
Processing millet is not without its difficulties:
- Impurities like sand, stones, and mud can damage machinery and lower product quality.
- Moisture in grains makes them harder to process, reduces recovery rates, and can lead to pest infestations.
- Varying grain sizes require skilled machine operators to handle specialized equipment.
Millet Processing Machinery
Setting up a millet processing unit involves several types of machinery for cleaning, grading, dehulling, and producing value-added products. Below is an overview of key machines:
1. Grader Cum Aspirator
The grader is essential for the initial cleaning process, where it removes impurities like straw, stones, and sand particles. It uses different sieve sizes to handle various millet types.
Before using the machine, the millet must be dried to 11–12% moisture content to prevent clogging. A grader typically has three sieves:
- Top sieve: Removes large objects like stones and straw.
- Middle sieve: Sorts out high-quality millet grains.
- Bottom sieve: Filters out fine particles like sand.
Graders are available in different sizes and configurations, with some including aspirators and destoners to improve efficiency.
Uses:
- Before hulling: Removes dust, stones, and foreign materials from millet.
- After hulling: Separates hulled and unhulled grains, husk-rich flour, and broken kernels.
2. Destoner
A destoner uses vibration and air movement to separate millet grains from stones and other dense materials. Small millets require destoners with fine mesh sizes.
Versions available:
- Destoner alone
- Destoner with aspirator
- Destoner with grader and aspirator
This machine reduces labor and significantly increases processing speed. It also extends the life of the de-hullers by preventing damage from stones.
Uses:
- Before hulling: Removes heavy contaminants like stones and mud balls.
- After hulling: Separates fractions of hulls from unhulled grains.
3. Combination Huller/Aspirator
After cleaning, the next step is dehulling, where the husk is removed. There are two types of de-hullers:
- Centrifugal De-huller: The impeller throws grains against a casing to separate the husk.
- Abrasive De-huller: Uses grinding stones (or rubber rollers) to shear the husk off the grain.
The quality of dehulling depends on how well the millet rice retains its bran layer after processing.
References:
- Ambrose, Dawn & Annamalai, S. & Naik, Ravindra & Dubey, Anurag & Chakraborty, Subir. (2017). Performance studies on millet processing machinery for tribal livelihood promotion. Journal of Applied and Natural Science. 9. 1796-1800. 10.31018/jans.v9i3.1441.
- Shaik, Kaleemullah & Reddy, Raveendra & Prabhakar, B. (2023). Performance evaluation of minor millet processing machines suitable for small and medium scale industries. 12. 2726-2729.
- Mundassery, Athira & Ramaswamy, Janci & Natarajan, Tharanidevi & Haridas, Soorya & Nedungadi, Prema. (2024). Modern and conventional processing technologies and their impact on the quality of different millets. Food Science and Biotechnology. 33. 10.1007/s10068-024-01579-z.
- https://machinepoint.in/products/rubber-roller-rice-mill-and -millet-processing-machine
- https://perfure.in/products/millet-processing-machines/centrifugal-millet-huller
Further reading
Millets: Types, Benefits, and History of Domestication
Panicum miliaceum – Millets seeds
How to grow Finger Millet – A Comprehensive Guide
Reviving Amaranth: The Ancient Grain Making a Modern Comeback in Sustainable Agriculture
Sorghum plant: Characteristics, Importance, Distribution and Uses
