Potatoes is among the most consumed staple food crops, being a major source of carbohydrates, proteins, vitamins, minerals, antioxidants and essential amino acids (Andre et al., 2007). Potato is a valuable crop for food security and income generation especially in subtropical climates. Potato production in East and Southern Africa is dominated by smallholder farmers. The total potato production area in East and Southern Africa is estimated at over 800,000 ha, producing about 9 million tons. In Kenya, potato is the second most important crop after maize, contributing approximately USD 300-400 million annually to the economy (MoALFC, 2019). The potato value chain employs about 3.3 million people directly and indirectly as producers (growers), brokers, market agents, transporters, processors, vendors, retailers and exporters.
Growers who are predominantly smallholders are estimated at 800,000 (USAID Report, 2015). Increase in global population and urbanization has intensified consumption of potatoes, especially given its high potential for processing, leading to increased production. Productivity of potatoes in the Southern Africa is by far high at about 157% of the world average at 32t/ha compared to 20t/ha. The prospects for growth of fresh potato market makes potato a good alternative for addressing food prices, which opens up opportunities for rural development in the region (Cott et al., 2020). Globally, the crop is grown in a wide range of climatic conditions both in the tropics and subtropics during cool and dry seasons (although under irrigation) (Ganie et al., 2013).
Some of the value addition opportunities along the potato value chain include; sorting, grading, packaging, storage and processing. Sorting of the potato should be done immediately after harvesting. It helps in identifying the damaged/bruised potato, diseased, and any other foreign material such soil clods which might cause deterioration of the harvested potato in the store. Sorting when done in terms of potato sizes is a necessity for farmers to get a premium market price as well as specialized market outlet. Sorting is also done based on the skin colour of the potato tuber harvested. It is therefore a value addition opportunity where one can decide to specialize on sorting of the potato tubers for farmers after they done the harvesting.
Grading is another value addition opportunity along the potato value chain. Majority of potato producers encounter huge loss due to poor grading. When the potato tubers are not harvested properly, there is mixture of grades and it leads to low bargaining power for a better price. Potato tuber grading is done based on size and shape, which leads to different categories of Ware, Seed and Charts. Ware potato is graded as; ≤ 28mm is graded as charts, between 35-50mm is graded as small size, between 50-80mm is graded as medium size and ≥80mm is graded as large size. Labeling of the potato bags is done according to variety description and weight for easy of identification. Therefore, this brings an opportunity for potato grading expertise to showcase their skills and experience to help farmers prevent the post-harvest losses along the potato value chain. Grading also helps the potato producers and traders to influence determination of prices.
Inset; harvested potatoes.
In summary, sorting in potatoes refer to removal of rotten, diseased, infected and cut tubers while grading refer to categorization of tubers based on their variety, size, shape and physical characteristics.
(Photo courtesy of https://businessfocus.co.ke-irish-potatoes/)