Investing in solar drying technology
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CTA. 2008. Investing in solar drying technology. Rural Radio Resource Pack 08/1. Wageningen, The Netherlands: CTA.
Permanent link to this item: http://hdl.handle.net/10568/57215
A hygienic, fast and cheap way to preserve and add value to produce
Investing in solar drying technology Cue: Drying produce in the open air works. But in Kenya, Winnie Onyimbo discovers another way of drying fruits and vegetables that can fetch a good price at the market. She speaks to a lady who is passionate about solar drying technology. Margaret Mimoh is from Honey Care Africa Ltd, a cooperative which - as the name suggests - makes money from beekeeping. But recently, members of her cooperative have decided to take up another initiative. They have decided to invest in solar drying technology to preserve and keep fruits all year round. Solar drying works by trapping heat inside a box or frame covered with plastic sheets, with a wire mesh base to allow air to circulate. The trapped heat causes the fruits or vegetables to lose their moisture, and dries them out ? but the heat is not enough to cook them. Margaret Mimoh explains how it is done ? starting with the selection process. IN: ?First you have to get?? OUT: ?give it a longer shelf life.? DUR?N: 5?20? BACK ANNOUNCEMENT: That was Winnie Onyimbo speaking to Margaret Mimoh from Honey Care Africa Ltd. Could investing in solar trying technology be worth it? The interview comes from a resource pack produced by CTA. Transcript Mimoh First you have to get ripe fruits, not over-ripened because if it?s over- ripened then slicing will be a problem because it will get mashed. So what happens is you have to wash the fruit, then you peel it and then you slice it in small slices maybe three millimetres to about five millimetres thick and then you place them on the drier, on the drying tray and then you put them inside the drier itself then you leave it there to dry. Onyimbo I would like you to give me a brief explanation on what the solar drier that is used for drying looks like? Mimoh The structure that is used for drying fruit is a very simple one. It is sort of, we should say, like a frame, maybe one metre by one metre and then it is covered with netting mesh, black netting mesh and then with a clear polythene sheet. The reason why we have the black netting and the clear polythene sheet is heat is allowed to get into the drier itself through the sheet and then it is absorbed by the netting mesh which now allows the air to circulate into the solar drier easily and then it extracts the moisture from the fruits allowing them to dry. Onyimbo How big is it? Mimoh The bigness will depend on the quantity of fruits that you would like to dry, like drying three kilos of fruit you will need one metre by one metre square of the frame with about two or three drying trays inside it. Onyimbo So this is a kind of drier that you use to dry fruits, please explain to me what is this that I am seeing? Mimoh This is the polythene sheet, it is very simple and it is locally available. We are always careful to get the right material for drying because when sunlight passes through this, there might be some chemical reaction between the polythene and the heat under and the fruit. Onyimbo I am also seeing it is a bit different from the polythene that we are used to, this seems to be harder, harder to touch? Mimoh Yes it is hard because even if you put a very light one there will not be as much heat as possible that would go in and dry the fruit so we use these ones so that you have more heat and also durability because you know when there is a lot of heat it tends to wear out. So we also do not want to be replacing like each and every time. The polythene sheet covers the three sides. You see on the three sides you have the polythene sheet and on the top side and then on the front side where you slide in the trays you have the netting mesh and this netting mesh - as I explained - it is locally available also in the market and it has to be black because black absorbs heat. Then when you open this (SFX opening drier) you have the trays. You slide them inside here and then you will be placing your fruits here on this tray here just the small pieces that you have cut, the slices you place them on the tray. Onyimbo What advantages does this solar drier have in comparison to drying fruits in the open sun? Mimoh There are aspects of health issues and hygiene. So if you basically maybe just take fruits and dry them in the open air of course you are exposing them to a lot of dust then maybe bacteria and those kind of things. And also the other thing is the nutritional value that is in the fruit will definitely be lost because it is exposed so it will not dry. There is no air circulating when you are drying in the open air. Onyimbo How about the time spent, is it faster drying in a drier than drying in the open sun? Mimoh When we have enough sunlight it would take a whole day, just one day, but if you do not really have good weather there is not enough sunlight it would take even two-to-three days to dry. Onyimbo Where can materials for such a solar drier be found by a smallscale farmer in Africa? Mimoh The materials are locally available in the market. So basically we say that they will need to be trained on how to fabricate the driers and how to go about the process of the drying. So it is not that the material is difficult to get, it is locally available in the market. The netting mesh in fact it is even used for tents. Onyimbo Are there any nutrients that are lost when drying? Mimoh In the fruits not really it is only the water that is lost during drying but most of the nutrients are maintained. So it is just as nutritious as the fresh fruit only that it does not have water. When you are drying it is only that you are removing water from it to give it a longer shelf life. End of track