GirlNextDoor Posted March 8, 2009 Share Posted March 8, 2009 http://www.scienceinafrica.co.za/2004/sept...frigeration.htm The Zeer Pot - a Nigerian invention keeps food fresh without electricity Musa Elkheir, Scidev.net Zeers at the Women's Development Association in Darfur. Photo by Mohamed Majzoub. [DARFUR] Hawa Osman is a farmer in Darfur, Sudan. She grows tomatoes, okra, carrots, and rocket lettuce, and also has small orchard of guava trees. In the hot weather of Darfur, Hawa used to lose half of the crops she hoped to sell each day in the market of Al Fashir, the capital city of North Darfur, because of inadequate storage facilities — and no electricity or refrigerator — in her small canteen, the shed made out of wood and palm leaves in which she displays her products to clients. But these days she is selling fresher produce and making bigger profit. This is because of an ingenious device — the zeer pot — that was invented by a Nigerian teacher, Mohammed Bah Abba and introduced to Darfur last year. The zeer is a large pot inside which fits another smaller pot with a clay lid. The space between the two pots is filled with sand, creating an insulating layer around the inner pot. The sand is then kept damp by adding water at regular intervals — generally twice a day — reducing the temperature within the inner post decrease. Each zeer can contain 12 kg of vegetables, and costs less than US$2 to produce. Experiments assessing its ability to extend shelf life show that tomatoes and guavas can be kept for 20 days, compared to just two without. Even rocket, which usually lasts only a day before wilting, can be kept for five days. Amina Abas, who sells zeers in the Al Fashir marketplace, says that she has found a high demand for the pot, as almost every family accommodates a family of refugees from the fighting in the region. "As a result, there is a need for zeer for keeping water and vegetables and preserving fruit to meet the needs not only of the host family, but also of the refugee family," she says. "It is really great." Hawa was the first person to use the zeer technology in her canteen. An information sheet attached to the pot tells her how long different produce can be kept. Before getting her zeer Hawa used to have to carry any unsold crops home each day. During the six-hour walk the vegetables would end up rotten because of the heat. Preservation is a key issue for food security. A good harvest is a rarity in the harsh climate of North Darfur; but even when farmers and small-scale producers produce a strong crop, they still face the problem of preserving the fruit and vegetables they've grown. Dry heat and dust reduce the 'shelf-life' of foods such as tomatoes, okra and carrots to as little as two or three days, making it essential to get good quality produce quickly into the marketplace. And the fact that food must be consumed quickly means that wastage is high. Since its introduction in November 2002, 110 families in Darfur have adopted the zeer. On average, two zeers are used in homes, while women on the market will have three to four. "It is simple and appropriate technology to me, as a farmer always works to keep her produce fresh and in top condition," says Hawa. "I was able to understand and use it within a week, and the technology rapidly became my bread and butter." She points out that she has to look after both herself and three children. "This technology has helped me gain a suitable income to meet my family's daily needs. I see it as the most positive turning point in my life, in that it has allowed me to become self-sufficient." Furthermore, both producer and consumer benefit. For the farmer, the zeer increases sales opportunities and for the consumer the result is an increased supply of vegetables and fruits in marketplace. The zeer is the brainchild of teacher Mohammed Bah Abba. Bah Abba passed his idea to the Intermediate Technology Development Group (ITDG), which, with the assistance of researchers at the University of Al Fashir, carried out experiments to measure its value in maintaining nutrient content and extending the shelf life of vegetables. As a result, the Women's Association for Earthenware Manufacturing in Darfur, with the support of ITDG, is now producing and selling zeers for food preservation in the Al Fashir area. Iman Mohamed Ibrahim of ITDG says women using the zeer to preserve their vegetables on the market can make an additional 25 to 30 per cent profit on their income. He points out, however, that it can have many other uses. "It can be used for storing sorghum and millets for a long time, as it protects from humidity when it is dry, preventing fungi from developing." The zeer can also keep water at a temperature of about 15 degree Celsius. "In the camp, it is used as a water pot, to store relief items, and even as a clothes cupboard," he says. There is also a health benefit. Mahmoud Ali, hygiene officer for the Al Fasir Municipality, says the zeer helps maintain the vitamin and nutrient content of the vegetables, and prevent disease by keeping flies off the food. "Before the technology came along, vegetables on the display shelves attracted flies, resulting in stomach disease such as dysentery, " he says. "Now that vegetables can be kept fresh for longer and away from flies, there is a remarkable decrease in such sorts of cases." Link to comment
Canned Nerd Posted March 8, 2009 Share Posted March 8, 2009 Impressive. Goes to show what man's mind can invent when there is a need. Link to comment
Cat Posted March 8, 2009 Share Posted March 8, 2009 Good find, GirlNextDoor! You reminded me that we had some stuff on making it yourself here, so I bumped up the old thread. I believe it was mentioned in threads about keeping vital medications cool, too. I would *LOVE* to see if anyone here has tried it! Link to comment
sassenach Posted March 8, 2009 Share Posted March 8, 2009 One can make a raw lumber box also and wet it down to keep perishables longer, this is done in hot dry climates alot. You keep it damp and by evaporation it keeps milk and cheese and things cooler much longer. You also have shelves inside for the items. I do not have access to clay pots big enough to utilize the pot idea but it is a great one! Link to comment
SlingMama Posted March 11, 2009 Share Posted March 11, 2009 Last summer I put together a Zeer pot. I went to the local nursery and found two unglazed pots, one slightly smaller than the other. Each pot has a drainage hole in the bottom so DH helped me plug them up. We used lids from jelly jars and glued them over the holes and, surprisingly that worked and they didn't leak. I took sand from the kid's sand box (my DH had just built it so the sand was new), put some in the bottom of the big pot, placed the small pot inside and then poured sand around. I then poured and poured and poured water into the sand - it's amazing how much water it soaked up - and placed a damp cloth over the top. (Oh, and how in the world those Africans manage to transport their Zeer pots I have no idea. The weight of the pots + sand + the water in the sand + the water the pot wicks up = an amazingly heavy pot impossible for me to lift.) Now I thought the Zeer pot would be almost refrigerator cold. Nope. It's cool and humid but not that cold. What were my measurements? I had the Zeer pot in a shady part of my sunroom and the sunroom temp was about 90 degrees and the inside of the Zeer pot was 72 degrees. The strange thing though is that the food inside feels cooler than that, especially if the vegetable are resting against the sides of the pot. End result was that I was very happy with the way the Zeer kept my vegetables. I put zucchini, tomatoes, etc. in the pot (which was great because last summer the kitchen was at times spilling over with produce) and all the vegetables kept much better than at room temperature. The concept of the Zeer pot was a raging success only ... Mold. After about a week (maybe week and a half?) the pots started to get black mold on them. And I live in the desert southwest so we don't do mold here. I had to pull the inner pot, scrub the pots and treat everything with vinegar. I thought of putting in bleach but I wasn't sure about it getting on the food, plus the smell of it. Anyway, I tried again and the mold came back. Now another thing I just thought of, and I haven't tried, is baking the sand. However, I still wonder if even baking the sand would keep the mold away indefinitely. I wonder. Seems anything that stays damp for days is bound to get little spores again and start growing. You know, it's starting to warm up here. Maybe I can pull my Zeer pot apart, bake the sand in the sun, put it back together, maybe add some vinegar to the water and let you know what happens. I'd really like to get this to work. Link to comment
SlingMama Posted March 11, 2009 Share Posted March 11, 2009 Mullling this some more I think I did bake the sand. I know after at least one mold episode I completely dismantled the Zeer pot, dried both pots in the sun and (I think?) baked the sand in the sun. Although I could try baking the sand at high heat in the oven and see if that helps. However, I'm of the opinion that whatever course I take the Zeer pot will need to be cleaned and dried a minimum of every few weeks. Best case scenario would be to have two Zeer pots so one could be drying while the other was in use. Link to comment
Girl Next Door Posted March 11, 2009 Share Posted March 11, 2009 What happens if you add vinegar to the sand? And what about a "dolly" type device they sell to put trees and stuff on? You know the kind you use to bring fruit ornamental fruit trees in out of the cold overnight? Link to comment
Homemaker Posted March 11, 2009 Share Posted March 11, 2009 If you improvise and make your own zeer pot, be careful to not allow your food to touch the clay pot. I remember when the craze was to bake bread in clay pots. We were warned that the commonly found nursery pots contained lead. They said to be sure the pot was specifically made for food prep. I had a thought... you might be able to extend the shelf life of the items you put in the zeer pot by keeping them in an outdoor pit or down in a root cellar. Link to comment
Girl Next Door Posted March 11, 2009 Share Posted March 11, 2009 I am picturing specially made clay pots with round racks inside of graduating sizes so they stack at different heights. Link to comment
Cat Posted March 11, 2009 Share Posted March 11, 2009 Well, I went to dogpile.com and did a search for "zeer pot + mold". Looking over the results, I found this info... ~~~~~~ At 3:41 AM, November 23, 2006, BobRainbow said... One problem that I found in the developed world was that our pots don't seem to be porous enough. They are fired too high and don't allow enough evaporation. You also need quite a high ambient temperature to make them work. I tried some while it was coolish and they did absolutely nothing... I was annoyed as I'd had dataloggers in them for a week to see how cool they got! **** At 10:51 AM, November 23, 2006, S. Drumm said... Douglas, Good post. To Rainbow Bob's point, the ambient humidity reduces the enthalpy of the system which in turn lowers the amount of heat that can be removed by evaporation. In short, techniques which rely on water-based evaporation work great in the mountains and desert...and not at all in the humid mid-South (where I live). **** At 12:01 PM, November 23, 2006, Scott A. Meister said... S. Drumm and Rainbow Bob, thanks for the comments. As for Rainbow Bobs comments about the clay not being porous enough. I believe there is a point to be made there. There are many different types of clay, and I imagine you'll get different results from different kinds of clay. I think the clay they're working with in Africa, probably just happens to be perfect for the job. **** At 12:43 AM, August 28, 2007, DJEB said... Zeer-pot style evaporative cooling is only possible in dry conditions (i.e. low humidity). While it would not cause freezing if brought on a huge scale such as a house, it would be tremendously wasteful of water - never a good idea. http://permaculturetokyo.blogspot.com/2006...ve-cooling.html ~~~~~~ And how they make it... http://practicalaction.org/docs/region_sud...efrigerator.pdf ~~~~~~ (Cat) I'm guessing that at home, they don't move them, and in the markets, they set it up after they arrive. ~~~~~~ OTHER KINDS OF COOLING ACTION... 9-28-2006 @ 1:31PM Ron Evans said... When I was young and used to go on hunting trips to remote areas for a few days at a time, we had a similar low tech way of keeping food cool. We had a tin box, possibly six or so cubic feet, that was covered with two or three wraps of burlap (old potato sacks). The box was filled with food (and beer of course) and placed at the edge of a creek. The burlap surrounding the box was well soaked. The end of the long piece of burlap that surrounded the box was placed in the creek so the box would be continually kept wet through capillary action. If the weather was extremely hot, every couple of hours, the burlap on the box would be soaked with water. The evaporation of the water keep the food good for several days and the beer cold enough until you didn't care if the beer was cold or hot. **** 9-28-2006 @ 3:41PM Zeke said... Ron Evans, Why didn't you just put it in the creek with a rope? **** 9-28-2006 @ 4:17PM Ron Evans said... Zeke - The evaporation of water from the sacks surrounding the tin box keeps the contents cooler than the temperature of the creek. **** 9-29-2006 @ 5:25AM Alyx said... In the 1960s, my family lived in rural (very rural) Dorset, with no fridge, and we used a similar method to keep butter and milk cool. Unglazed earthenware covers went over the bottle or butterdish, with the whole stood in a dish of water, so that evaporation from the earthenware cover kept the contents cool. They were quite effective, as I recall. **** 9-29-2006 @ 3:19PM DK said... In Arizona during the depression the same technique was used to keep food fresh. It is the same method that "evaporative coolers" or "swamp coolers" use to cool homes in desert areas without humidity. It is a great system and should be promoted for every one's use as an alternative to expensive air conditioning which burns resources. http://www.slashfood.com/2006/09/28/how-co...r-pot/#comments ~~~~~~ Link to comment
SlingMama Posted March 11, 2009 Share Posted March 11, 2009 "And what about a "dolly" type device they sell to put trees and stuff on? You know the kind you use to bring fruit ornamental fruit trees in out of the cold overnight?" I think a dolly underneath the Zeer pot would help if you had to move it however, once set up, the Zeer really doesn't have to be moved around much. I do have a small towel under mine and, if I have to shift the pot around, I grab the edge of the towel and drag the pot to where I want it. But I was under the impression some Africans transported their produce in the pot. But I think Cat must be right that and they just set it up once they arrive. "One problem that I found in the developed world was that our pots don't seem to be porous enough. They are fired too high and don't allow enough evaporation." As far as the pots being porous. It did take me awhile to find pots I thought would be suitable. My pots have a rough texture and are a orange / white-ish color - they are kind of raw looking - and they do wick water. After I put the water into the sand between the pots I can watch the pots change color as they absorb the water. Now the whole lead thing I never thought of that. "In short, techniques which rely on water-based evaporation work great in the mountains and desert...and not at all in the humid mid-South (where I live)." This is exactly right. A Zeer pot will not work in humid conditions. Even though I live in the desert my Zeer pot actually gets cooler placed in my hot sunroom than it in my kitchen. The Zeer pot needs circulation of dry air and, since we keep the windows or door of the sunroom open in the daytime, the Zeer pots work best in there. Plus my kitchen is kind of dark, which would encourage the mold. When I was young and used to go on hunting trips to remote areas for a few days at a time, we had a similar low tech way of keeping food cool. We had a tin box, possibly six or so cubic feet, that was covered with two or three wraps of burlap (old potato sacks). The box was filled with food and placed at the edge of a creek. The burlap surrounding the box was well soaked. The end of the long piece of burlap that surrounded the box was placed in the creek so the box would be continually kept wet through capillary action. If the weather was extremely hot, every couple of hours, the burlap on the box would be soaked with water. I read that tidbit last year (after I'd bought my pots ) and I wonder if a tin box would be better than a Zeer pot - from a mold standpoint. Wonder if it would be possible to use a large tub of water instead of a creek. And if the burlap started to get icky then just wash it or dry it in the sun. Burlap sounds a lot easier to switch out than dismantling a Zeer. Link to comment
ttruscott Posted March 11, 2009 Share Posted March 11, 2009 Here are some examples of a similar system: EVAPORATIVE FOOD COOLER http://www.cd3wd.com/cd3wd_40/vita/foodproc/en/foodproc.htm http://www.omick.net/food_preservation/food_preservation.htm Ted Link to comment
westbrook Posted March 11, 2009 Share Posted March 11, 2009 http://mrssurvival.com/forums/index.php?showtopic=21588 Link to comment
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