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Clay pot refrigerator inexpensive, needs no power, causes no pollution
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Monday, 04 November, 2019, 08 : 00 AM [IST]
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Mehul Vora
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Imagine a day without fridge? It may be difficult to imagine, today we are so dependent on fridge to stock leftover food, milk, fruits and vegetables.
The refrigerator preserves food and keeps it safe from dangerous bacterial growth until one has a chance to eat it. The refrigerator can be considered as one of the biggest technological advancements in the present days. Amidst the busy schedules, one finds it really easy to cook food and refrigerate it as food does not get spoiled. Also, some people even go for meal prepping. Meal prepping is simply preparing meals ahead of time and then storing it. Some people also cook food in large portions and then store it in the refrigerator as it simplifies their work. Although refrigeration increases shelf life it also causes, loss of nutrients, discolouration, and lot of other effects on food. The chloro-flouro-carbons emitted by modern refrigerators pose a threat to the environment as well.
The days when refrigerator did not exist, refrigeration existed in the most natural form. Right from the prehistoric age humans are known to use clay. In India we are known to use matki or earthen pot for storing water and keeping the water cold and fight scorching summer heat. The cooling process works through evaporative cooling. Capillary action causes water to evaporate from the mini-pores in the pot, taking the heat from the water inside, thus making the water inside cooler than the outside temperature. The similar technology is known to be used as natural refrigerant.
Types of natural clay refrigerants
Many clay pots were discovered in Indus Valley Civilisation around 3000 BC which were probably used for storing as well as cooling water similar to the present-day ghara and matki used in India and Pakistan. There have been evidences that evaporative cooling was used as early as the Old Kingdom of Egypt, around 2500 BC. Frescoes show slaves fanning water jars, which would increase air flow around the porous jars and aid evaporation, cooling the contents. A zeer is constructed by placing a clay pot within a larger clay pot with wet sand in between the pots and a wet cloth on top. The device cools as the water evaporates, allowing refrigeration in hot, dry climate.
Although the evaporative cooling can be difficult in humid and arid regions, sea water can be used instead to aid in the cooling process. If there is an impermeable separation layer between the food and the porous pots without contaminating the food.
In Spain, botijos are popular. A botijo is a porous clay container used to keep and to cool water; they have been in use for centuries, and are still relatively widespread. Botijos are favoured most by the low Mediterranean climate; locally, the cooling effect is known as "botijo effect."
In rural northern Nigeria in the 1990s, Mohamed Bah Abba developed the Pot-in-Pot Preservation Cooling System, consisting of a small clay pot placed inside a larger one, and the space between the two filled with moist sand. The inner pot is filled with fruit, vegetables or soft drinks and covered with a wet cloth.
Mansukhbai Prajapati, an Indian entrepreneur, also put in noteworthy efforts to create his proprietary product mitticool fridge using similar technology.
Advantages of clay refrigeration
A clay pot refrigerator is inexpensive and does not consume electricity. It causes no pollution as the refrigerant used is water. These refrigerators can be afforded easily by the rural people of undeveloped countries. A considerable temperature drop is observed within a short period of time and the efficiencies are quite satisfactory. Clay refrigeration can keep fruits and vegetables fresh for a week. It also has lot of health benefits; Clay has lot of minerals and a cooling effect on the body. Clay also helps in dealing with stomach related ailments, skin related ailments. Therefore right from ancient time drinking water in clay pots was advised.
Clay refrigeration as a business model
Clay refrigeration can be a strong product to penetrate the consumers, corporates can create innovative solutions using the evaporative cooling with clay. Clay solutions will not only be ecofriendly and help in saving the environment but will also help the potters of the country to make sustainable livelihood. Today the earthenware are back in the market in form of kadai, pans and so on.
Consumers tend to have a preference for earthenware, therefore if there are smaller solutions made for clay refrigeration it can be a good commodity. As cost of electricity and manufacturing is soaring high day by day, and there are global climatic challenges, a good scope of natural refrigerant like clay is predicted.
Fast developments in material science and technology contribute to the discovery of alternatives to clay which could give an improved performance. As a business case study the pot-in-pot innovation of Abba, hired skilled pot makers to mass-produce the first batch of 5,000 Pot-in-Pots. He received the Rolex Award for Enterprise in 2001 and used his $75,000 award to make the invention available throughout Nigeria. The pots sell at 40 US cents a pair. Even India’s mitticool fridge has been popular commodity in rural India at an affordable rate of over Rs 3,000. A corporate research and intervention can really help this market grow further.
(The author is culinary historian. He can be contacted at mv2574@gmail.com)
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