A power operated size-based Chinese potato (koorka) grader and a method of grading thereof developed by ICAR-Central Tuber Crops Research Institute (CTCRI) in Thiruvananthapuram has been granted patent by Indian Patent Office. T. Krishnakumar, Scientist is the lead inventor of the technology along with M.S. Sajeev, Principal Scientist; C. Pradeepika, Scientist; R. Muthuraj, Principal Scientist and D. Jaganathan, Senior Scientist. Working on the principle of rotating motion of the grading unit through a prime mover, the Chinese potato grader sorts the tubers into four different size classes; small (below 20 mm diameter), medium (20.1-30 mm), large (30.1-40 mm) and very large (above 40 mm), most common commercially marketed tubers in India. The prime mover works with an electric motor with a gear box (25:1) to reduce the speed. With rotational speed of the grading drum and guiding roller of 10 and 1100 rpm respectively, it works on a single phase with 0.75 kW per hour power consumption with an average power cost of Rs. 5 per hour. Grading efficiency is 96 percent. In comparison to 50 man-days of labour requirement for sorting Chinese potato tubers harvested from an area of one hectare, this machine needs only two man-days for sorting the same quantity of tuber. It can grade/sort one tonne of tuber in an hour for which the average cost including labour is 150 rupees whereas manual grading of the same quanity will cost 1500 rupees. CTCRI has commercialized the technology for its production by giving a non-exclusive license to M/s Stoneheat Technologies, an engineering manufacturing firm in Rajapalayam in Tamil Nadu and interested people / farmer groups can buy the machine from the company. CTCRI took up this project based on need assessment survey of Chinese potato growers considering the very high expenditure on manual grading which significantly reduces the profit of the growers who are mostly resource-poor people concentrated in the districts of Tenkasi and Tirunelveli in Tamil Nadu and Thrissur, Palakkad and Ernakulam in Kerala besides many other places. Grading the tubers will fetch more remuneration to farmers with grade one fetching five to six times more price than grade four. Development of improved varieties, photoinsensitivity, lack of availability of quality planting materials, nematode infestation, need for planting and harvesting machinery and price instability prioritized researchable issues in a brainstorming meeting on Chinese potato organized by CTCRI in October 2023 and research programmes in these directions are now being geared up.
