Difference between pages "How to Build a Windpump (Principles)" and "How to Preserve Tomato"

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=Windpumping - Technical Brief=
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==Short Description==
 +
*'''Problem:'''
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*'''Idea:'''
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*'''Difficulty:'''
 +
*'''Price Range:'''
 +
*'''Material Needeed:'''
 +
*'''Geographic Area:'''
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*'''Competencies:'''
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*'''How Many people?'''
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*'''How Long does it take?'''
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=Tomato Processing - Technical Brief=
  
 
<div class="booktext">
 
<div class="booktext">
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<div class="booktext">
 
<div class="booktext">
  
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Windpower technology dates back many centuries. There are historical claims that wind machines which harness the power of the wind date back to the time of the ancient Egyptians. Hero of Alexandria used a simple windmill to power an organ whilst the Babylonian emperor, Hammurabi, used windmills for an ambitious irrigation project as early as the 17th century BC. The Persians built windmills in the 7th century AD for milling and irrigation and rustic mills similar to these early vertical axis designs can still be found in the region today. In Europe the first windmills were seen much later, probably having been introduced by the English on their return from the crusades in the middle east or possibly transferred to Southern Europe by the Muslims after their conquest of the Iberian Peninsula. It was in Europe that much of the subsequent technical development took place. By the late part of the 13th century the typical 'European windmill' had been developed and this became the norm until further developments were introduced during the 18th century. At the end of the 19th century there were more than 30,000 windmills in Europe, used primarily for the milling of grain and water pumping. The first half of the 20th saw further development, particularly a move toward propeller type wind machines for electricity production.
+
The demand for tomato processing usually arises from a need to preserve the product for cooking purposes (inclusion in stews, soups, curries etc) out of season or to add value for extra income. Traditionally, the most important methods used are concentration (to a paste or purée) and drying either fruit pieces or to a powder. These remain the most suitable processes for many people to use and form the bulk of this brief. It should be noted that high quality ‘salad’ tomatoes have the highest value when sold fresh and in good condition. These would not normally be used for processing, unless for home use to save excess at the height of the season.
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The major advances in the design of the windpump, however, took place in the USA. The technology was taken up and developed by the early pioneers or settlers who needed a method of lifting ground water for irrigation, for watering of livestock and later for providing water for steam locomotives which began to spread across the country. There were several significant technical developments to the commercial machines during this time; the ability of the machine to turn into the prevailing wind automatically; the development of a self governing mechanism which automatically turned the machine out of the wind when the wind velocity became high enough to cause damage; various improvements in rotor design and general durability and the introduction of gearing mechanisms. The technology was soon taken up worldwide, especially in the newly settled arid regions, such as South Africa, Australia and Argentina, where previously a lack of water had always prevented settlement and economic development in remote areas. By the 1920's 6 million windpumps were being used in the USA alone and their manufacture and use had become commonplace on every continent.
 
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But the glory of the windpump was short-lived. With the advent of cheap fossil fuels in the 1950's and 1960's and the development of pumping technology the windpump became almost obsolete in the USA. Nowadays, with regular fuel crises and rising prices there has been a revival of interest in windpower but the windpump has yet to regain the status it held during its heyday.
 
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'''Windpumping for rural areas of the developing world'''
 
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There are manufacturers in several developing countries now producing windpumps. The uptake of wind machines for water pumping, however, has been generally very slow even though the technology is well suited to the demand of many regions of Africa, Asia and Latin America. Where they are used, the demand is for one of the following end uses:<br />
 
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<blockquote>
 
−
 
 
−
• village water supplies<br /> • irrigation<br /> • livestock water supplies
 
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−
</blockquote>
 
−
 
 
−
<br /> Water pumping is one of the most basic and widespread energy needs in rural areas of the world. It has been estimated that half the world's rural population does not have access to clean water supplies.
 
  
 
</div>
 
</div>
  
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==Technical==
+
==Raw material quality==
  
 
<div class="booktext">
 
<div class="booktext">
  
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'''The power in the wind'''
+
For each of the processes described below the tomatoes should be ripe, red, firm to soft, free of all mould growth (by cutting out infected parts) and free of stems, leaves, dirt and other soils (by washing). It is less important if the tomatoes have surface blemishes or splits/cracks (provided these are not infected) as in most processes they will be cut or pulped.
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−
The wind systems that exist over the earth's surface are a result of variations in air pressure. These are in turn due to the variations in solar heating. Warm air rises and cooler air rushes in to take its place. Wind is merely the movement of air from one place to another. There are global wind patterns related to large scale solar heating of different regions of the earth's surface and seasonal variations in solar incidence. There are also localised wind patterns due the effects of temperature differences between land and seas, or mountains and valleys.
 
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−
Windspeed data can be obtained from wind maps or from the meteorology office. Unfortunately the general availability and reliability of windspeed data is extremely poor in many regions of the world. However, significant areas of the world have mean windspeeds of above 3m/s which make the use of windpumps an economically attractive option. It is important to obtain accurate windspeed data for the site in mind before any decision can be made as to its suitability. Methods for assessing the mean windspeed are found in the relevant texts (see the 'References and resources' section at the end of this fact sheet).
 
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−
The power in the wind is proportional to:<br />
 
−
 
 
−
<blockquote>
 
−
 
 
−
• the area of windmill being swept by the wind<br /> • the cube of the wind speed<br /> • the air density - which varies with altitude
 
−
 
 
−
</blockquote>
 
−
 
 
−
<br /> The formula used for calculating the power in the wind is shown below:<br />
 
−
 
 
−
<blockquote>
 
−
 
 
−
P<sub>W</sub> = ½ ρ A V<sup>3</sup>
 
−
 
 
−
</blockquote><div align="left"><br />
 
−
 
 
−
{| cellpadding="5"
 
−
|- valign="top"
 
−
| valign="top" |
 
−
where,
 
−
| valign="top" |
 
−
P<sub>W</sub> is power in watts available in the wind (W)
 
−
|- valign="top"
 
−
| valign="top" |
 
−
ρ is the air density in kilograms per cubic metre (kg/m<sup>3</sup>)
 
−
|- valign="top"
 
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| valign="top" |
 
−
A is the swept rotor area in square metres (m<sup>2</sup>)
 
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|- valign="top"
 
−
| valign="top" |
 
−
V is the wind speed in metres per second (m/s)
 
−
|}
 
  
 
</div>
 
</div>
  
−
The fact that the power is proportional to the cube of the wind speed is very significant. This can be demonstrated by pointing out that if the wind speed doubles then the power in the wind increases by a factor of eight! It is therefore worthwhile finding a site which has a relatively high mean wind speed.
+
==Processing==
  
−
'''Wind into watts'''
+
<div class="booktext">
  
−
Although the power equation above gives us the power in the wind, the actual power that we can extract from the wind is significantly less than this figure suggests. The actual power will depend on several factors, such as the type of machine and rotor used, the sophistication of blade design, friction losses, the losses in the pump or other equipment connected to the wind machine, and there are also physical limits to the amount of power which can be extracted realistically from the wind. It can been shown theoretically that any windmill can only possibly extract a maximum of 59.3% of the power from the wind (this is known as the Betz limit). In reality, for a windpump, this figure is usually around 30% to 40% and for a large electricity producing turbine around 45% maximum (see the section on coefficient of performance below)
+
'''Drying'''
  
−
So, modifying the formula for 'Power in the wind' we can say that the power that is produced by the wind machine can be given by:<br />
+
Traditional methods in hot, dry regions include sun drying. The tomato halves are placed on clean flat surfaces (eg roofs) with the cut side facing up or by threading the halves on to strings and hanging in the sun from a branch or beam. In both cases, drying is relatively rapid (depending on the temperature and humidity of the air) but there may be contamination of the product by insects, dirt and dust, this can be reduced by covering the tomatoes with fine muslin cloth or mosquito netting. The end product is dark, red, leathery pieces with a strong tomato flavour. Re-hydration is relatively slow, but this may be unimportant in cooking applications. Provided that the humidity is low, the dried product will keep without special packaging for several months. If the humidity rises the product will go mouldy and should be protected either by suitable packaging (eg sealed plastic bags - preferably polypropylene or thick polythene, or in sealed pottery jars) or dried slowly over a fire to a low moisture content. The tomatoes should be far enough away from the fire to prevent cooking they will be fully dried when they are hard and brittle.
  
−
<blockquote>
+
If the climate is not hot and dry, an artificial drier could be considered but the cost of the drier and fuel should be carefully calculated to see if it is economic to dry this often low value food.
  
−
P<sub>M</sub> = ½.C<sub>p</sub> ρ A V<sup>3</sup>
+
When tomatoes are dried to a low moisture content, so that they are hard (eg 5% water), they can be pounded or milled to a powder. This is more convenient to use and store (eg sealed glass or pottery jars or sealed polypropylene film bags thin polypropylene - the most common type of plastic will not stop moisture entering the product and subsequent mould growth within a few weeks). Layers of pulp can also be dried to a rubbery fruit leather and stored in plastic film. Alternatively the post dried pulp can be formed into balls or cubes and then dried in the sun or over a fire.
  
−
</blockquote><div align="left"><br />
+
<center>
  
−
{| cellpadding="5"
+
[[Image:p1.jpg]]<br /> Figure 1: Sorting the tomatoes. Processing unit at Walewela, Matale, Sri Lanka.<br />
−
|- valign="top"
 
−
| valign="top" |
 
−
where,
 
−
| valign="top" |
 
−
P<sub>M</sub> is power (in watts) available from the machine
 
−
|- valign="top"
 
−
| valign="top" |
 
−
C<sub>p</sub> is the coefficient of performance of the wind machine
 
−
|}
 
  
−
</div>
+
</center><blockquote>
  
−
It is also worth bearing in mind that a wind machine will only operate at maximum efficiency for a fraction of the time it is running, due to variations in wind speed. A rough estimate of the output from a windpump can be obtained using the following equation;<br />
+
©Zul/Practical Action
  
−
<blockquote>
+
</blockquote>
−
 
 
−
P<sub>A</sub> = 0.1 A V<sup>3</sup>
 
  
−
</blockquote><div align="left"><br />
+
<br />'''Concentration'''
−
 
 
−
{| cellpadding="5"
 
−
|- valign="top"
 
−
| valign="top" |
 
−
where,
 
−
| valign="top" |
 
−
P<sub>A</sub> is the average power output in watts over the year
 
−
|- valign="top"
 
−
| valign="top" |
 
−
V is the mean annual windspeed in m/s
 
−
|}
 
  
−
</div>
+
Tomato pulp can be prepared using a pestle and mortar, some types of mills (eg ‘Posho’ mill in West Africa) or by small pulping machines. It is usually necessary to remove seeds and skins this can be done by sieving through a medium mesh (eg 1-2mm holes) or, in the case of some of the pulpers, these parts are separated by the machine.
  
−
'''Principles of wind energy conversion'''
+
'''Juice/squash'''
  
−
There are two primary physical principles by which energy can be extracted from the wind; these are through the creation of either lift or drag force (or through a combination of the two). The difference between drag and lift is illustrated by the difference between using a spinnaker sail, which fills like a parachute and pulls a sailing boat with the wind, and a Bermuda rig, the familiar triangular sail which deflects with wind and allows a sailing boat to travel across the wind or slightly into the wind.
+
Tomato juice can be separated from the pulp by filtering but more commonly the entire pulp is used as ‘juice’. This can be preserved by hot water pasteurising in sealed bottles at 90-100°C for at least 10 minutes followed by cooling to room temperature (Figure 2) or by hot filling into sterile bottles. A certain amount of separation of pulp and liquid during storage is inevitable - with pulp accumulating at the bottom of the bottle. However, clear separation into a pale liquid and a solid pulp layer is evidence of under-pasteurisation. This is not likely to be harmful but is less attractive. Some small-scale producers have found that adding 0.3% thickener (eg sodium alginate) completely prevents separation. This is a permitted additive in most countries but may be expensive and is not really necessary.
  
−
Drag forces provide the most obvious means of propulsion, these being the forces felt by a person (or object) exposed to the wind. Lift forces are the most efficient means of propulsion but being more subtle than drag forces are not so well understood. The basic features that characterise lift and drag are:<br />
+
<center>
  
−
<blockquote>
+
[[Image:p2a.gif]]<br /> Figure 2: Bottle cooling system
  
−
• drag is in the direction of air flow<br /> • lift is perpendicular to the direction of air flow<br /> • generation of lift always causes a certain amount of drag to be developed<br /> • with a good aerofoil, the lift produced can be more than thirty times greater than the drag<br /> • lift devices are generally more efficient than drag devices
+
</center><center>
  
−
</blockquote>
+
[[Image:p2b.gif]]<br />'''Flow Diagram'''
−
 
 
−
<br />'''Types and characteristics of rotors'''
 
−
 
 
−
There are two main families of windmachines: vertical axis machines and horizontal axis machines. These can in turn use either lift or drag forces to harness the wind. The horizontal axis lift device is the type most commonly used. In fact other than a few experimental machines virtually all windmills come under this category.
 
−
 
 
−
There are several technical parameters that are used to characterise windmill rotors. The ''tip-speed ratio'' is defined as the ratio of the speed of the extremities of a windmill rotor to the speed of the free wind. Drag devices always have tip-speed ratios less than one and hence turn slowly, whereas lift devices can have high tip-speed ratios (up to 13:1) and hence turn quickly relative to the wind.
 
−
 
 
−
The proportion of the power in the wind that the rotor can extract is termed the ''coefficient of performance'' (or power coefficient or efficiency; symbol C<sub>p</sub>) and its variation as a function of tip-speed ratio is commonly used to characterise different types of rotor. As mentioned earlier there is an upper limit of C<sub>p</sub> = 59.3%, although in practice real wind rotors have maximum C<sub>p</sub> values in the range of 25%-45%.
 
−
 
 
−
''Solidity'' is usually defined as the percentage of the area of the rotor, which contains material rather than air (see Figures 1 & 2 below). High-solidity machines carry a lot of material and have coarse blade angles. They generate much higher starting torque (torque is the twisting or rotary force produced by the rotor) than low-solidity machines but are inherently less efficient than low-solidity machines. The windpump is generally of this type. Low-solidity machines tend to be used for electricity generation. High solidity machines will have a low tip-speed ratio and vice versa.
 
−
 
 
−
<center>
 
−
 
 
−
[[Image:p4a.jpg]]<br /> Figure 1: Low solidity rotor ©Practical Action
 
  
 
</center>
 
</center>
  
−
The choice of rotor is dictated largely by the characteristic of the load and hence of the end use. Some common rotor types and their characteristics are shown in Table 1 below.
+
Tomato squash is tomato pulp with added sugar syrup to give a concentration of 30-50% total solids (°Brix) measured by refractometer. It is not a widespread product as people tend to prefer squashes made from other fruits but it may well be worth investigating in your own area. It is processed in a similar way to juice and may in addition contain up to 100ppm of sodium (or potassium) benzoate preservative in most countries (check with your local Bureau of Standards).
  
−
<center>
+
Tomatoes can be boiled to evaporate the water. Depending on how much water is removed and what other ingredients are mixed into the pulp, it is possible to obtain a large number of products. Examples are given in Table 1.
  
−
[[Image:p4b.jpg]]<br /> Figure 1: High solidity rotor ©Practical Action
+
Table 1: Products from tomato pulp
  
−
</center><div align="left">
+
<div align="left">
  
 
{| border="1" cellpadding="5"
 
{| border="1" cellpadding="5"
 
|- valign="top"
 
|- valign="top"
 
| valign="top" |
 
| valign="top" |
−
Type
+
<center>Solids content (%)*</center>
 
| valign="top" |
 
| valign="top" |
−
Speed
+
<center>Temperature (at sea level)</center>
 
| valign="top" |
 
| valign="top" |
−
Torque
+
<center>Other ingredients</center>
 +
|- valign="top"
 
| valign="top" |
 
| valign="top" |
−
C<sub>p</sub>
+
Paste
 
| valign="top" |
 
| valign="top" |
−
Solidity (%)
+
<center>40</center>
 
| valign="top" |
 
| valign="top" |
−
Use
+
<center>(101)</center>
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|- valign="top"
 
 
| valign="top" |
 
| valign="top" |
−
'''Horizontal axis'''
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<center>-</center>
 
|- valign="top"
 
|- valign="top"
 
| valign="top" |
 
| valign="top" |
−
Multi blade
+
Puree
 
| valign="top" |
 
| valign="top" |
−
Low
+
<center>34</center>
 
| valign="top" |
 
| valign="top" |
−
High
+
<center>(100)</center>
 
| valign="top" |
 
| valign="top" |
−
0.25 - 0.4
+
<center>-</center>
−
| valign="top" |
 
−
50 - 80
 
−
| valign="top" |
 
−
Mechanical power
 
 
|- valign="top"
 
|- valign="top"
 
| valign="top" |
 
| valign="top" |
−
Three-bladed aerofoil
+
Jam
 
| valign="top" |
 
| valign="top" |
−
High
+
<center>68-70</center>
 
| valign="top" |
 
| valign="top" |
−
Low
+
<center>(106)</center>
 
| valign="top" |
 
| valign="top" |
−
up to 0.45
+
(pectin), sugar, (acid)
−
| valign="top" |
 
−
Less than 5
 
−
| valign="top" |
 
−
Electricity production
 
 
|- valign="top"
 
|- valign="top"
 
| valign="top" |
 
| valign="top" |
−
'''Vertical axis'''
+
Chutney
−
|- valign="top"
 
 
| valign="top" |
 
| valign="top" |
−
Panemone
+
<center>42</center>
 
| valign="top" |
 
| valign="top" |
−
Low
+
<center>(101)</center>
 
| valign="top" |
 
| valign="top" |
−
Medium
+
vinegar, salt, spices
 +
|- valign="top"
 
| valign="top" |
 
| valign="top" |
−
less than 0.1
+
Ketchup
 
| valign="top" |
 
| valign="top" |
−
50
+
<center>35</center>
 
| valign="top" |
 
| valign="top" |
−
Mechanical power
+
<center>(100)</center>
 
|- valign="top"
 
|- valign="top"
 
| valign="top" |
 
| valign="top" |
−
Darrieus
+
Soup
 
| valign="top" |
 
| valign="top" |
−
Moderate
+
<center>16</center>
 
| valign="top" |
 
| valign="top" |
−
Very low
+
<center>(100)</center>
 
| valign="top" |
 
| valign="top" |
−
0.25 - 0.35
+
flour, salt, sugar
−
| valign="top" |
 
−
10 - 20
 
−
| valign="top" |
 
−
Electricity production
 
 
|}
 
|}
  
−
</div>
+
</div><blockquote>
  
−
Table 1: Comparison of rotor types
+
<nowiki>* Usually measured by refractometer as °Brix. Figures in brackets are final temperature of boiling at sea level, which is an alternative way of measuring solids content (at higher elevations the boiling point is progressively reduced and separate technical advice is needed if you are above approximately 2000m)</nowiki>
  
−
</div>
+
</blockquote>
  
−
==Water pumping==
+
<br /> The basic preservation principle behind all of these products is to remove water by boiling to a) heat the product to destroy enzymes and micro-organisms and b) concentrate the product so that contaminating micro-organisms cannot re-grow.
  
−
<div class="booktext">
+
This can be done in an open pan over a fire. It is necessary to heat slowly - especially when the product is more concentrated - to prevent it burning onto the pan. It should also be stirred continuously which is very labour intensive (and hot work). The product will be a dark red paste with a strong taste of tomato.
  
−
'''Matching rotor and pump'''
+
A better colour and faster process can be achieved using a steam jacketed boiling pan with steam from a boiler but this is expensive and should only be considered for larger scales of operation. The bright red colour of imported tomato pastes and purées can only be obtained by using vacuum evaporators and at present there is no low-cost small-scale equipment available to our knowledge.
  
−
When installing a windpump it is important to match the characteristics of the pump and the wind machine. A good interaction between pump and rotor is essential. The most common type of pump used for water pumping (especially for borehole water pumping) in conjunction with a windmill is the reciprocating or piston pump. The piston pump tends to have a high torque requirement on starting because, when starting, the rotor has to provide enough torque to overcome the weight of the pump rods and water in the rising main - once the rotor is turning, the torque requirement decreases because of the momentum of the revolving rotor. The windspeed can then drop to about 2/3 of the start-up windspeed before the windpump will stop.
+
After boiling to the correct solids concentration (usually 65-75° Brix by refractometer or to a temperature of 104-106°C at sea level) the product is filled into pre-sterilised jars (100°C for ten minutes in steam or water) and cooled to room temperature. A selection of typical recipes for each product is given below.
  
−
Other common pump types used for windpumping are the progressive cavity or 'Mono' pump and the centrifugal pump. Both have advantages in certain circumstances but both also tend to be expensive and less commonly used.
+
'''Tomato jam'''
  
−
Figure 3. illustrates a typical example of a modern multi-bladed windpump. The high solidity means high starting and running torque and low running speed which is desirable for use with the piston pump.
+
1kg tomato pulp<br /> 1kg sugar<br /> (pectin and citric acid not usually necessary but 0.1% pectin and adjustment to pH3.3 may be needed).
  
−
It is obviously important to match the water pumping demand with the available wind and hence decide upon a suitable rotor size. To calculate the demand we need to know the following data:<br />
+
'''Green tomato chutney'''<br />
  
 
<blockquote>
 
<blockquote>
  
−
• The head to which the water is to be pumped - in metres<br /> • volume of water to be pumped per day - in metres cubed
+
1kg tomatoes<br /> 125g cooking apples<br /> 500g onions<br /> 100g sultanas<br /> 450 ml vinegar<br /> 500g sugar<br /> 1 level teaspoon salt<br /> ½ level teaspoon mustard<br /> ¼ level teaspoon pepper<br /> 2 level teaspoons curry powder
  
 
</blockquote>
 
</blockquote>
  
−
<br /> For water at sea level the approximate energy requirement can be calculated using the following equation:<br />
+
<br /> Peel the tomatoes, chop the apples and onions into small pieces. Mix all the ingredients except the sugar and boil gently until soft. Add the sugar and boil for a further 30 minutes. Pour into jars and tie down.
 +
 
 +
'''Tomato ketchup for 1kg'''<br />
  
 
<blockquote>
 
<blockquote>
  
−
E = 0.002725 x volume x head (in kilowatt-hours)
+
420g tomato puree<br /> 150g sugar<br /> 300g vinegar (10% acetic acid)<br /> 300g salt<br /> 70g onion pulp<br /> 30g (garlic puree and other spices to taste)
  
 
</blockquote>
 
</blockquote>
  
−
<br /> Typically pumping heads can vary between a few metres and 100m (and occasionally more), whilst the volume of water required can vary from a few cubic metres a day for domestic use to a few hundred cubic metres for irrigation.
+
<br />'''Tomato soup for 1kg'''<br />
  
−
'''Anatomy of windpump'''
+
<blockquote>
  
−
A borehole is by far the most common water source from which the windpump will draw water. A classic multiblade farm windpump has a piston pump pumping to an elevated storage tank. There are many other configurations possible, depending on the nature of the water source and the demand. These machines have rotor diameters of between 1.5 and 8 metres but seldom exceed 4 or 5 metres. The power is transmitted from the rotor to the pump rods via a gearing system or via a direct drive mechanism. The movement of the pump rods cause the pump to lift water to the tank. Water can then be fed into the distribution network from the tank. The function of the tail vane is to keep the rotor orientated into the wind. Most windpumps have a tail vane, which is designed, for automatic furling (turning the machine out of the wind) at high wind speeds to prevent damage.
+
60g tomato puree<br /> 30g sugar<br /> 10g salt<br /> 20g flour<br /> 20g spices/garlic puree/onion puree etc to taste<br /> 860g water (mix ingredients oil fill into pasteurised jars and pasteurise at 90ºC for 15 minutes.
  
−
<center>
+
</blockquote></div>
 +
 
 +
==References and further reading==
 +
'''This Howtopedia entry was derived from the Practical Action Technical Brief ''Tomato Processing ''.  <br />To look at the original document follow this link: '''<br />
 +
http://www.practicalaction.org/?id=technical_briefs_food_processing
 +
<div class="booktext">
  
−
[[Image:p5.jpg]]<br /> Figure 3: The Kitjito Windpump. Used to pump ground water in the Bhel region of Turkana for the Nomadic Pastorlists ©Practical Action
+
• ''Semi-processing of Tomatoes'', Practical Action Technical Brief
  
−
</center>
+
• ''How to grow tomato and peppers: agrodok 17:'' M. Amati et al, Agromisa, 1989
  
−
'''Windpumping with electricity'''
+
• ''Small-scale Food Processing: A Directory of Equipment & Methods'', S. Azam-Ali et al, ITDG Publishing, 2003
  
−
Although the multiblade windpump is by far the most common windpump in use, it is not the only option available. Another option, especially where there is a requirement for the pump to be sited remote from the wind machine, is to use an aerogenerator to provide electricity for an electric pump. Although they tend to be more expensive, they do have the advantage that the electricity can be used for other applications when not pumping and also that the electricity can be stored in batteries for use when the windspeed is insufficient for direct electricity supply.
+
• ''Tomato and Fruit Processing, Preserving and Packaging: An example of a village Factory'', Guus de Klein, CIEPAC/TOOL, 1993
  
 
</div>
 
</div>
  
−
==Other issues==
+
==Equipment suppliers==
  
 
<div class="booktext">
 
<div class="booktext">
  
−
'''Local manufacture'''
+
Note: This is a selective list of suppliers and does not imply endorsement Practical Action.
  
−
Windpumps are manufactured in small numbers in various countries throughout the world. There are manufacturers producing windpumps in Europe, Australia, South Africa and the USA for export, but there are also commercial enterprises in developing countries manufacturing windpumps. One such manufacturer, RIIC (the Rural Industries and Innovations Centre) is mentioned below.
+
DISEG Diseno Industrial y Servicios Generales<br /> Av. Jose Carlos Mariategui<br /> 1256 Villa Maria del Triunfo<br /> Lima<br /> Peru<br /> Tel: +51 14 283 1417<br /> Fruit pulper. This machine can be used as a pulper and as a sieve machine.<br /> It has 2 mesh sizes - 3mm and 0.5mm.<br /> Capacity: 40-50 kg/hour. Electric.
  
−
There have been several projects over the last couple of decades with the aim of transferring windpump technology to manufacturers in the South, and there has been some success. One such success story is the Kijito windpump (See figure 3), manufactured in Kenya. This windpump was originally developed by the Intermediate Technology Development Group - ITDG (now known as Practical Action) based in the UK in conjunction with Bobs Harries Engineering Ltd. (BHEL), Kenya. BHEL have further developed the Kijito design and currently produce about 25 windpumps a year with a capacity to produce up to 50 machines.
+
Kaps Engineers 831, G.I.D.C.<br /> Makarpura<br /> Vadodara - 390 010<br /> India<br /> Tel: +91 265 644692/640785/644407<br /> Fax: +91 265 643178/642185<br /> Capacity: 25-40 kg/hour<br />
  
−
<div align="left">
+
<blockquote>
  
−
{| border="1" cellpadding="5"
+
• VM Mikro Pulverisers<br /> Capacity: 25-40 kg/hour<br /> • VM Pulverisers for medium fine grinding of soft to semi-hard materials.<br /> Capacity: 100-3000 kg/hour. Electric
−
|- valign="top"
 
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| valign="top" |
 
−
'''Ownership, usage, maintenance and environmental impact'''
 
  
−
'''User Perspective - Windpumps in Botswana'''
+
</blockquote>
  
−
A survey was conducted in Botswana on owners/ users of windpumps''.'' The aim was to determine the ownership, procurement and installation, use, environmental impact and promotion of windpumps. The survey revealed that 54% of the windpumps were owned by households and 23% by farmers groups or syndicates. The rest (23%) were owned by the community. The majority of the windpumps (85%) were purchased and the rest were donated. Fifty-six per cent of the respondents purchased windpumps or raised the money from the banks to purchase them, whereas 18% utilised group contributions. Most of the respondents purchased the windpumps from RIIC, the local supplier. The installation of the windpumps was done by RIIC in 69% of the cases and by owners and foreign dealers in 23% and 8% respectively. Ninety-two per cent of the respondents were of the opinion that the installation was done satisfactorily. The operators had been trained by the supplier in 39% of the cases and the remainder had either taught themselves (31%) or been taught by the local technicians (8%).
+
<br /> Lehman Hardware and Appliances Inc.<br /> P.O. Box 41<br /> Kidron<br /> Ohio 44636<br /> USA<br /> Tel orders: +1 877 438 5346<br /> Tel enquiries: +1 888 438 5346<br /> Website: <u>http://www.lehmans.com</u><br />
  
−
All respondents revealed that windpumps were used for pumping water for livestock as well as for irrigation and domestic purposes. Ninety-two per cent of the respondents were of the opinion that the windpump had significantly improved their water supply. Eighty-four per cent thought that windpumps satisfied the water needs of the community. Thirty-one per cent depended on windpumps entirely for their water pumping, while 69% had other systems. The respondents perceived windpumps as a good technology mainly because they were cheaper to use. One of the problems associated with the use of windpumps was the high frequency of breakdowns. Forty-six per cent indicated that they broke down once a year, 31% twice a year and 23% more than three times a year. Major repairs were done by RIIC (54%), local technicians (8%) or a combination of the two (8%).
+
<blockquote>
  
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The study also investigated the perception of respondents of the environmental impact of the use of windpumps. The majority (85%) thought the windpumps improve the scenery, whereas 15% said they do not make a difference. No negative impacts were reported. It was also the view of 92% of the respondents that the noise form the windpumps is not a nuisance. The respondents thought that the adoption of the windpump technology was constrained by factors such as the lack of appropriate policies, lack of awareness of the technology, high costs of maintenance and inadequate wind regimes.
+
• Suppliers of hand operated fruit presses and grinders.<br /> • Victoria strainer
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|}
 
  
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</div>
+
</blockquote>
  
−
Source: Mosimanyane et al 1995 (cited in Karekezi & Ranja 1997)
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<br /> Alvan Blanch<br /> Chelworth<br /> Malmesbury<br /> Wiltshire<br /> SN16 9SG<br /> United Kingdom<br /> Tel: +44 (0) 666 577333<br /> Fax: +44 (0) 666 577339<br />
  
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</div>
+
<blockquote>
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==References and resources==
 
  
−
'''This Howtopedia entry was derived from the Practical Action Technical Brief ''Windpumping''. <br />To look at the original document follow this link: http://www.practicalaction.org/?id=technical_briefs_energy'''<br />
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• Fruit Pulper/Siever Used for the extraction of juice or pulp from fruit. Power: Electric
−
<div class="booktext">
 
  
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1. P. Fraenkel, R. Barlow, F. Crick, A. Derrick and V. Bokalders: Windpumps - A guide for development workers. ITDG Publishing, 1993
+
• Plate grinding mills suitable for wet and dry grinding of grains and other crops.
  
−
2. David, A. Spera: Wind Turbine Technology, fundamental concepts of wind turbine engineering. ASME Press, 1994
+
</blockquote>
  
−
3. E. W. Golding: The Generation of Electricity by Wind Power. Redwood Burn Limited, Trowbridge, 1976
+
<br /> Kenwood Limited<br /> New Lane<br /> Havant<br /> Hampshire<br /> PO9 2NH<br /> United Kingdom<br /> Tel: +44 (0) 23 9247 6000<br /> Fax: +44 (0) 23 9239 2400<br /> Website: <u>http://www.kenwood.co.uk/</u><br />
  
−
4. Hugh Piggot: Windpower Workshop, building your own wind turbine. Centre for Alternative Technology, 1997
+
<blockquote>
  
−
5. S. Karekezi and T. Ranja: Renewable Energy Technologies in Africa. AFREPREN / SEI, 1997
+
• Manufacture: Kenwood Chef, etc. Worldwide distribution.
  
−
6. C. Borg, and H. Oden: The Kijito Windpump - A Private Initiative in Kenyan Rural Water Supply, Master's Thesis, Chalmers University of Technology, Goteborg, 1995
+
</blockquote>
  
−
7. Paul T. Smulders and Jan de Jongh: Wind Pumping: Status, Prospects and Barriers, Article, Renewable Energy, Vol. 5 Part 1, pp. 587-594, 1994
+
<br /> Narangs Corporation P-25,<br /> Connaught Place<br /> New Delhi - 110 001<br /> India<br /> Telephone: +91 11 336 3547<br /> Fax: +91 11 374 6705<br />
  
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</div>
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<blockquote>
  
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==Manufacturers==
+
• Tomato and grape crusher. This machine will crush tomatoes and other soft fruits.
  
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<div class="booktext">
+
</blockquote>
  
−
Note: This is a selective list of suppliers and does not imply endorsement by Practical Action.
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<br /> Gardners Corporation 6 Doctors Lane<br /> Near Gole Market<br /> PO Box 299<br /> New Delhi - 110001<br /> India<br /> Tel: +91 11 334 4287/336 3640<br /> Fax: +91 11 371 7179<br />
  
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Neale Consulting Engineers Ltd., Highfield,<br /> Pilcot Hill, Dogmersfield, Hants. RG27 8SX,<br /> United Kingdom<br /> Tel: +44 (0)1252 629199<br /> Fax: +44 (0)1252 815625<br /> Website:<br /><u>http://www.tribology.co.uk/poldaw.htm</u>
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<blockquote>
  
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Manufacture the Poldaw 3.5m Windpump.<br /> Southern Cross Industries (Pty.) Ltd.,<br /> P.O. Box 627, Bloemfontein 9300,<br /> South Africa.<br /> Tel: +27 (0)51 4343861<br /> Fax: +27 (0)51 4343575<br /> Manufacture and supply windpumps.
+
• Soup strainer. A very handy and fast device for pulping juices and tomatoes using a revolving paddle. Power: Electric
  
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The Rural Industries Innovations Centre,<br /> (Subsidiary of Rural Industries Promotions Company. Website: <u>http://www.ripco.co.bw</u>),<br /> P/Bag 11, Kanye, Botswana.<br /> Tel: +267 340392<br /> Fax: +267 340642
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</blockquote>
  
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Abachem Engineering Ltd., Jessop Way,<br /> Newark, Notts. NG24 2ER, UK.<br /> Tel: +44 (0)1636 676483<br /> Fax: +44 (0)1636 708632.<br /> Manufacture and supply windpump and 'submerged control leakage pump'.
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<br />
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Stewarts & Lloyds, 37 Leopold Takawira St.,<br /> Harare, P.O. Box 784, Zimbabwe.<br /> Tel: +263 4 708191<br /> Fax: + 263 4 790972<br /> Manufactures of the IT Windpump.
 
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Bobs Harries Engineering Ltd., P.O.Box 40,<br /> Thika, Kenya.<br /> Tel: +254 151 47234 or 47250<br /> Fax: +254 151 47233
 
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'''Practical Action, The Schumacher Centre for Technology & Development'''<br />'''Bourton Hall, Bourton-on-Dunsmore, Rugby, Warwickshire CV23 9QZ, UK'''<br />'''Tel: +44 (0)1926 634400 Fax: +44 (0)1926 634401 E-mail: [mailto:Infoserv@practicalaction.org.uk Infoserv@practicalaction.org.uk] Web: http://www.practicalaction.org'''<br />'''Intermediate Technology Development Group Ltd Patron HRH -The Prince of Wales. KG, KT, GCB'''<br />'''Company Rag. No 871954, England Rag. Charity No 247257 VAT No 241 5154 92'''
 
  
 
</div>
 
</div>
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=='''Useful addresses'''==
 
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'''Practical Action'''
 
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The Schumacher Centre for Technology & Development, Bourton on Dunsmore, RUGBY, CV23 9QZ, United Kingdom.<br />
 
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'''Tel.:''' +44 (0) 1926 634400, '''Fax:''' +44 (0) 1926 634401
 
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'''e-mail:'''practicalaction@practicalaction.org.uk '''web:'''www.practicalaction.org
 
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<center>[[Image:Pa-logo-200x103.gif]]</center>
 
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=='''Categories:'''==
 
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[[category:Example]]
 
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[[Category:Difficult]]
 
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[[Category:More than 200 US$]]
 
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[[Category:Up to 5 Persons]] [[Category:More than 5 Persons]]
 
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[[Category:Global Technology]]
 
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[[Category:Energy]] [[Category:Mechanics]]
 

Revision as of 19:27, 17 August 2006

Short Description

  • Problem:
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  • How Long does it take?

Tomato Processing - Technical Brief

PRACTICAL ACTION
Technology challenging poverty

Introduction

The demand for tomato processing usually arises from a need to preserve the product for cooking purposes (inclusion in stews, soups, curries etc) out of season or to add value for extra income. Traditionally, the most important methods used are concentration (to a paste or purée) and drying either fruit pieces or to a powder. These remain the most suitable processes for many people to use and form the bulk of this brief. It should be noted that high quality ‘salad’ tomatoes have the highest value when sold fresh and in good condition. These would not normally be used for processing, unless for home use to save excess at the height of the season.

Raw material quality

For each of the processes described below the tomatoes should be ripe, red, firm to soft, free of all mould growth (by cutting out infected parts) and free of stems, leaves, dirt and other soils (by washing). It is less important if the tomatoes have surface blemishes or splits/cracks (provided these are not infected) as in most processes they will be cut or pulped.

Processing

Drying

Traditional methods in hot, dry regions include sun drying. The tomato halves are placed on clean flat surfaces (eg roofs) with the cut side facing up or by threading the halves on to strings and hanging in the sun from a branch or beam. In both cases, drying is relatively rapid (depending on the temperature and humidity of the air) but there may be contamination of the product by insects, dirt and dust, this can be reduced by covering the tomatoes with fine muslin cloth or mosquito netting. The end product is dark, red, leathery pieces with a strong tomato flavour. Re-hydration is relatively slow, but this may be unimportant in cooking applications. Provided that the humidity is low, the dried product will keep without special packaging for several months. If the humidity rises the product will go mouldy and should be protected either by suitable packaging (eg sealed plastic bags - preferably polypropylene or thick polythene, or in sealed pottery jars) or dried slowly over a fire to a low moisture content. The tomatoes should be far enough away from the fire to prevent cooking they will be fully dried when they are hard and brittle.

If the climate is not hot and dry, an artificial drier could be considered but the cost of the drier and fuel should be carefully calculated to see if it is economic to dry this often low value food.

When tomatoes are dried to a low moisture content, so that they are hard (eg 5% water), they can be pounded or milled to a powder. This is more convenient to use and store (eg sealed glass or pottery jars or sealed polypropylene film bags thin polypropylene - the most common type of plastic will not stop moisture entering the product and subsequent mould growth within a few weeks). Layers of pulp can also be dried to a rubbery fruit leather and stored in plastic film. Alternatively the post dried pulp can be formed into balls or cubes and then dried in the sun or over a fire.

File:P1.jpg
Figure 1: Sorting the tomatoes. Processing unit at Walewela, Matale, Sri Lanka.

©Zul/Practical Action


Concentration

Tomato pulp can be prepared using a pestle and mortar, some types of mills (eg ‘Posho’ mill in West Africa) or by small pulping machines. It is usually necessary to remove seeds and skins this can be done by sieving through a medium mesh (eg 1-2mm holes) or, in the case of some of the pulpers, these parts are separated by the machine.

Juice/squash

Tomato juice can be separated from the pulp by filtering but more commonly the entire pulp is used as ‘juice’. This can be preserved by hot water pasteurising in sealed bottles at 90-100°C for at least 10 minutes followed by cooling to room temperature (Figure 2) or by hot filling into sterile bottles. A certain amount of separation of pulp and liquid during storage is inevitable - with pulp accumulating at the bottom of the bottle. However, clear separation into a pale liquid and a solid pulp layer is evidence of under-pasteurisation. This is not likely to be harmful but is less attractive. Some small-scale producers have found that adding 0.3% thickener (eg sodium alginate) completely prevents separation. This is a permitted additive in most countries but may be expensive and is not really necessary.

File:P2a.gif
Figure 2: Bottle cooling system

File:P2b.gif
Flow Diagram

Tomato squash is tomato pulp with added sugar syrup to give a concentration of 30-50% total solids (°Brix) measured by refractometer. It is not a widespread product as people tend to prefer squashes made from other fruits but it may well be worth investigating in your own area. It is processed in a similar way to juice and may in addition contain up to 100ppm of sodium (or potassium) benzoate preservative in most countries (check with your local Bureau of Standards).

Tomatoes can be boiled to evaporate the water. Depending on how much water is removed and what other ingredients are mixed into the pulp, it is possible to obtain a large number of products. Examples are given in Table 1.

Table 1: Products from tomato pulp

Solids content (%)*
Temperature (at sea level)
Other ingredients

Paste

40
(101)
-

Puree

34
(100)
-

Jam

68-70
(106)

(pectin), sugar, (acid)

Chutney

42
(101)

vinegar, salt, spices

Ketchup

35
(100)

Soup

16
(100)

flour, salt, sugar

* Usually measured by refractometer as °Brix. Figures in brackets are final temperature of boiling at sea level, which is an alternative way of measuring solids content (at higher elevations the boiling point is progressively reduced and separate technical advice is needed if you are above approximately 2000m)


The basic preservation principle behind all of these products is to remove water by boiling to a) heat the product to destroy enzymes and micro-organisms and b) concentrate the product so that contaminating micro-organisms cannot re-grow.

This can be done in an open pan over a fire. It is necessary to heat slowly - especially when the product is more concentrated - to prevent it burning onto the pan. It should also be stirred continuously which is very labour intensive (and hot work). The product will be a dark red paste with a strong taste of tomato.

A better colour and faster process can be achieved using a steam jacketed boiling pan with steam from a boiler but this is expensive and should only be considered for larger scales of operation. The bright red colour of imported tomato pastes and purées can only be obtained by using vacuum evaporators and at present there is no low-cost small-scale equipment available to our knowledge.

After boiling to the correct solids concentration (usually 65-75° Brix by refractometer or to a temperature of 104-106°C at sea level) the product is filled into pre-sterilised jars (100°C for ten minutes in steam or water) and cooled to room temperature. A selection of typical recipes for each product is given below.

Tomato jam

1kg tomato pulp
1kg sugar
(pectin and citric acid not usually necessary but 0.1% pectin and adjustment to pH3.3 may be needed).

Green tomato chutney

1kg tomatoes
125g cooking apples
500g onions
100g sultanas
450 ml vinegar
500g sugar
1 level teaspoon salt
½ level teaspoon mustard
¼ level teaspoon pepper
2 level teaspoons curry powder


Peel the tomatoes, chop the apples and onions into small pieces. Mix all the ingredients except the sugar and boil gently until soft. Add the sugar and boil for a further 30 minutes. Pour into jars and tie down.

Tomato ketchup for 1kg

420g tomato puree
150g sugar
300g vinegar (10% acetic acid)
300g salt
70g onion pulp
30g (garlic puree and other spices to taste)


Tomato soup for 1kg

60g tomato puree
30g sugar
10g salt
20g flour
20g spices/garlic puree/onion puree etc to taste
860g water (mix ingredients oil fill into pasteurised jars and pasteurise at 90ºC for 15 minutes.

References and further reading

This Howtopedia entry was derived from the Practical Action Technical Brief Tomato Processing .
To look at the original document follow this link:
http://www.practicalaction.org/?id=technical_briefs_food_processing

• Semi-processing of Tomatoes, Practical Action Technical Brief

• How to grow tomato and peppers: agrodok 17: M. Amati et al, Agromisa, 1989

• Small-scale Food Processing: A Directory of Equipment & Methods, S. Azam-Ali et al, ITDG Publishing, 2003

• Tomato and Fruit Processing, Preserving and Packaging: An example of a village Factory, Guus de Klein, CIEPAC/TOOL, 1993

Equipment suppliers

Note: This is a selective list of suppliers and does not imply endorsement Practical Action.

DISEG Diseno Industrial y Servicios Generales
Av. Jose Carlos Mariategui
1256 Villa Maria del Triunfo
Lima
Peru
Tel: +51 14 283 1417
Fruit pulper. This machine can be used as a pulper and as a sieve machine.
It has 2 mesh sizes - 3mm and 0.5mm.
Capacity: 40-50 kg/hour. Electric.

Kaps Engineers 831, G.I.D.C.
Makarpura
Vadodara - 390 010
India
Tel: +91 265 644692/640785/644407
Fax: +91 265 643178/642185
Capacity: 25-40 kg/hour

• VM Mikro Pulverisers
Capacity: 25-40 kg/hour
• VM Pulverisers for medium fine grinding of soft to semi-hard materials.
Capacity: 100-3000 kg/hour. Electric


Lehman Hardware and Appliances Inc.
P.O. Box 41
Kidron
Ohio 44636
USA
Tel orders: +1 877 438 5346
Tel enquiries: +1 888 438 5346
Website: http://www.lehmans.com

• Suppliers of hand operated fruit presses and grinders.
• Victoria strainer


Alvan Blanch
Chelworth
Malmesbury
Wiltshire
SN16 9SG
United Kingdom
Tel: +44 (0) 666 577333
Fax: +44 (0) 666 577339

• Fruit Pulper/Siever Used for the extraction of juice or pulp from fruit. Power: Electric

• Plate grinding mills suitable for wet and dry grinding of grains and other crops.


Kenwood Limited
New Lane
Havant
Hampshire
PO9 2NH
United Kingdom
Tel: +44 (0) 23 9247 6000
Fax: +44 (0) 23 9239 2400
Website: http://www.kenwood.co.uk/

• Manufacture: Kenwood Chef, etc. Worldwide distribution.


Narangs Corporation P-25,
Connaught Place
New Delhi - 110 001
India
Telephone: +91 11 336 3547
Fax: +91 11 374 6705

• Tomato and grape crusher. This machine will crush tomatoes and other soft fruits.


Gardners Corporation 6 Doctors Lane
Near Gole Market
PO Box 299
New Delhi - 110001
India
Tel: +91 11 334 4287/336 3640
Fax: +91 11 371 7179

• Soup strainer. A very handy and fast device for pulping juices and tomatoes using a revolving paddle. Power: Electric


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