Other than consuming the sweet potatoes as steamed food, there are other products that one can produce from sweet potatoes including chips and flour.
Requirements
- Mature sweet potato roots
- A clean area ideally raised working surfaces.
- Large plastic containers, preferably 10- to 20-litre buckets with lids
- Supply of clean water
- Knives for peeling and chipping
- A solar drier
Procedure
- Choosing the roots. The roots are harvested or purchased and sorted. Use the undamaged and mature potatoes – three to four months for the early maturing varieties and five to six months for the late maturing ones
- The potatoes are washed in clean water in large buckets, with water being changed as frequently as required.
- After washing, the potatoes are drained by being placing them on nylon sacks.
- The washed potatoes are peeled and chipped to uniform size (3-6 mm thick) manually, with sharp knives.
- Sweet potato chips are spread evenly on trays and loaded into a solar drier (can also be sun dried but the quality will be lower than that of a solar drier), dried for about eight hours until brittle, according to the sun’s intensity.
- The dried chips are packed in polyethene bags and stored in buckets until further processing to flour
- The potatoes are milled, using a hammer mill (village “posho” mill) into flour.
- The flour is packed in strong (thick gauge) black polythene bags, Labelled to state source, date of manufacture and expiry date (after six months).
- The bags are placed into buckets to protect the flour from light. If orange fleshed sweet potato is sliced and subjected to four different treatments
- Slicing while leaving the potatoes in open air
- Slicing and immersing the chips in water
- Slicing and immersing the chips in water mixed with sodium meta bisulphite
- Un-peeling the roots followed by slicing
- Steaming the potatoes for 25 minutes before slicing and drying
Treatment one
The chips will brown even before being put in the drier, the flour made from the dried chips subjected to this treatment will be discoloured due to oxidation. The orange colour will not be pronounced and the flour will have a brown coloration.
Treatment two
The orange colour leaches into the water and the flour made from these chips is nearing to white; the smell of the OFSP will though still be pronounced. However, the vitamin A is fat soluble and will not be lost in the soaking water
Treatment three
Chips immersed in water with Meta bisulphite will retain the orange colour. The flour made from these chips will be most attractive.
Treatment four
The peeling of the orange sweet potato is proved to be rich in nutrients, however on drying the peel will tend to blacken and the black substances will also be manifested in the flour which will makes the flour unattractive.
Treatment five
Steaming the potatoes for 25 minutes before slicing and drying will retain more orange colour and hence the carotenoids as compared to slicing and drying without steaming.
Slicing the potatoes and drying them immediately will retain as much carotenoids as pre-steaming. Therefore, we prefer slicing and drying without steaming because it saves energy and it is convenient in terms of labour.
The flour will also keep better than the fresh potatoes. The products that can be made from the potato flour included; cakes, biscuits, composite flour, buns, cookies and doughnuts.
