3 Preparation Plant Preparation plant for dehydration is very similar to that used by th canner and freezer, because up to the last stage of conser material is prepared in similar manner, other than to provide for the introduction of certain additives which are not common to either canned or frozen products This chapter defines very briefly the type of preparation plant used in a multi-product operation, the lay-out of which will have to be arranged to suit the production flow of several types of vegetable(or alternatively fruit without too much disturbance to the original positioning of the machines, when changing from one product to another The description of the various machines is accompanied by photographs and the brief outline of their function will be amplified in later chapters, which explain more concisely the processing details for a wide range of fruit, vegetables and liquid products It is stressed that some of the preparation plant described will only be required in a medium to large scale operation, because in a low budget project, full automation would be neither viable nor necessary, as such a plant may be able to be used with the simplest product cleaning facilities, peeler, cutter and some simple conveying equipment. Some old established factories in Eastern Europe, specialising in onion dehydration, have operated for years with a minimum of preparation machinery, being convinced that hand peeling of onions, for example, produces a much better product than a
3 Preparation Plant Preparation plant for dehydration is very similar to that used by the canner and freezer, because up to the last stage of conservation the raw material is prepared in similar manner, other than to provide for the introduction of certain additives which are not common to either canned or frozen products. This chapter defines very briefly the type of preparation plant used in a multi-product operation, the lay-out of which will have to be arranged to suit the production flow of several types of vegetable (or alternatively fruit) without too much disturbance to the original positioning of the machines, when changing from one product to another. The description of the various machines is accompanied by photographs and the brief outline of their function will be amplified in later chapters, which explain more concisely the processing details for a wide range of fruit, vegetables and liquid products. It is stressed that some of the preparation plant described will only be required in a medium to large scale operation, because in a low budget project, full automation would be neither viable nor necessary, as such a plant may be able to be used with the simplest product cleaning facilities, a peeler, cutter and some simple conveying equipment. Some old established factories in Eastern Europe, specialising in onion dehydration, have operated for years with a minimum of preparation machinery, being convinced that hand peeling of onions, for example, produces a much better product than a 39
machine and even their cutters have been substantially fabricated in their own workshops. However, as indicated in Table 1. 1.(imports into the UK), the volume produced in this type of factory is very small, and when world prices were low in the 1970 s many Romanian and Bulgarian factories ceased operations in dehydration and reverted to other forms of vegetable and fruit conservation. It is emphasised that the preparation plant described is'upstreamof the dryer Downstream plant is described in the chapteron selection, packing and sto CUT TERS (a) Dicers The dehydration process requires that produce be reduced to a fairly small particle size, otherwise the removalof water becomes an over-extended operation, with consequent damage to the colour, texture, appearance and general quality of the dried product. Also the rehydration 'factor deteriorates Dicers are cutting machines with three separate knife actions (1)a slicing knife positioned in the machines impeller, which rotates at approximately 190rpm, makes the first lateral slice as the product is fed into the machine. The thickness of the slice is adjustable but the maximum dimension is limited by the spacing of (2)the cross-cut knives, which are fixed to a spindle rotating at about 1400rpm. The impeller thrusts the first cut slices on to these cross-cut knives by centrifugal force, making strips ranging from 7 1mm to 13mm in width pre-determined by the thickness of the first slicing cut (3) The third cut is made with a row of circular knives that can be spaced in 3.2mm increments from 6.4 to 76mm apart. Julienne cuts are produced using circular knives spaced 4mm, 4.8mm or mm For this type of cut, the cross-cut knife spindle is replace with a slice guide roll, and the slice thickness(first cut)is djusted to suit the circular knife spacing A Model G dicer can be used as a slicer to produce any thickness up to 19mm. An inner chute must be used in these circumstances to guide slices across the slicing knife holder into the discharge chute The above description, and those given below, relate to one American designed machine, noted for its high performance and reliability, and it is used internationall
machine, and even their cutters have been substantially fabricated in their own workshops. However, as indicated in Table 1 .l. (imports into the UK), the volume produced in this type of factory is very small, and when world prices were low in the 1970‘s many Romanian and Bulgarian factories ceased operations in dehydration and reverted to other forms of vegetable and fruit conservation. It is emphasised that the preparation plant described is ‘upstream’ of the dryer. Downstream plant is described in the chapter on selection, packing and storage. CUTTERS (a) Dicers. The dehydration process requires that produce be reduced to a fairly small particle size, otherwise the removal of water becomes an overextended operation, with consequent damage to the colour, texture, appearance and general quality of the dried product. Also the rehydration ‘factor‘ deteriorates. Dicers are cutting machines with three separate knife actions: (1) a slicing knife positioned in the machine’s impeller, which rotates at approximately 19Orpm, makes the first lateral slice as the product is fed into the machine. The thickness of the slice is adjustable but the maximum dimension is limited by the spacing of (2) the cross-cut knives, which are fixed to a spindle rotating at about 1400rpm. The impeller thrusts the first cut slices on to these cross-cut knives by centrifugal force, making strips ranging from 7.lmm to 13mm in width, pre-determined by the thickness of the first slicing cut. (3) The third cut is made with a row of circular knives that can be spaced in 3.2mm increments from 6.4 to 76mm apart. Julienne cuts are produced using circular knives spaced 4mm, 4.8mm or 6.4mm apart. For this type of cut, the cross-cut knife spindle is replaced with a slice guide roll, and the slice thickness (first cut) is adjusted to suit the circular knife spacing. A Model G dicer can be used as a slicer to produce any thickness up to 19mm. An inner chute must be used in these circumstances to guide slices across the slicing knife holder into the discharge chute. The above description, and those given below, relate to one American designed machine, noted for its high performance and reliability, and it is used internationally. 40
There are other Continental makes built on similar lines, and the processor must judge which marque serves his purpose best in performance The dicer is perhaps the most flexible cutter available, and will handle quite a range of products but, with a wide product mix, other types of cutter will doubtless be needed Cutter knives require constant attention and should be sha every eight hour shift, especially when used on tough vegetables, such as carrots,swedes, turnips, cabbage, celeriac, etc. Failure to do this will give rise to a ragged product which will matt on the drying surface, whether it be a tray or a conveyor slat. This creates an impermeable mass which the air flow will not penetrate, and these conditions will delay drying or, at worst, will make even drying impossible achines are available for both cross-cut knives circular knives and slicing knives, and these can usually be supplied by the cutter manufacturers In a medium to large operation, it is obviously wise to duplicate all cutters, so that by having two in parallel, the knife change will not hold up the production flow and the product can be switched immediately, without any hold-up from one cutter to the stand-by machine. Each knife assembly can be removed with all the knives (ie cross-cut and circular) in situ, and indeed can be sharpened as a unit, without dismantling each knife separately or servicing This facility of course makes it possible for the smaller operator to remove and exchange a knife assembly, so long as he carries a spare assembly, nd in this way he can avoid having to duplicate the whole machine but, of course, there will be some delay in the actual removal of the old machinery and replacement by the spare one, and some production time will be lost The shift fitter must, as a priority, watch the condition of the cutting knives throughout his shift, very much as the seamer fitter in a cannery watches the quality of the double seam cans passing through a high speed can seamer at 1000 cans per minute. In both cases a lapse of attention at this point can spell trouble. Disposable knives avoid honing cost Where cutters are duplicated, it is obviously wise to install two of identical make, so that economy in carrying spare parts is achieved (b)J Cutter This is eminently suitable for bulb and leafy products, such as spinach, leeks, spring cabbage, bell peppers, parsley and other herbs, celery and citrus fruit and the peel The machine operates on the principle of a high speed belt carrying
There are other Continental makes, built on similar lines, and the processor must judge which marque serves his purpose best in performance and cost effectiveness. The dicer is perhaps the most flexible cutter available, and will handle quite a range of products but, with a wide product mix, other types of cutter will doubtless be needed. Cutter knives requk constant attention and should be sharpened every eight hour shift, especially when used on tough vegetables, such as carmts, swedes, turnips, cabbage, celeriac, etc. Failure to do this will give rise to a ragged product which will matt on the drying surface, whether it be a tray or a conveyor slat. This creates an impermeable mass which the air flow will not penetrate, and these conditions will delay drying or, at worst, will make even drying impossible. Honing machines are available for both crosscut knives, circular knives and slicing knives, and these can usually be supplied by the cutter manufacturers. In a medium to large operation, it is obviously wise to duplicate all cutters, so that by having two in parallel, the knife change will not hold up the production flow and the product can be switched immediately, without any hold-up from one cutter to the stand-by machine. Each knife assembly can be removed with all the knives (ie, cross-cut and circular) in situ, and indeed can be sharpened as a unit, without dismantling each knife separately for servicing. This facility of course makes it possible for the smaller operator to remove and exchange a knife assembly, so long as he carries a spare assembly, and in this way he can avoid having to duplicate the whole machine but, of course, there will be some delay in the actual removal of the old machinery and replacement by the spare one, and some production time will be lost. The shift fitter must, as a priority, watch the condition of the cutting knives throughout his shift, very much as the seamer fitter in a cannery watches the quality of the double seam cans passing through a high speed can seamer at lo00 cans per minute. In both cases a lapse of attention at this point can spell trouble. Disposable knives avoid honing costs. Where cutters are duplicated, it is obviously wise to install two of identical make, so that economy in carrying spare parts is achieved. (b) J Cutter This is eminently suitable for bulb and leafy products, such as spinach, leeks, spring cabbage, bell peppers, parsley and other herbs, celery and citrus fruit and the peel. The machine operates on the principle of a high speed belt carrying 41
the product to the cutting parts. A 152mm diameter feed roll is fitted at the feed end of the belt to the knives. This flattens the vegetable before entering the knives and forces them into the cutting area By the arrangement of the circular and cross-cut knives, the j cutter roduces square cuts ranging from 6 by 6mm to 13 by 13mm, the thickness of this square being the thickness of the original product. For example a capsicum with flesh 4mm thick would emerge as a square flake 6 by 6 by 4mm or a larger square if the knives were adjusted. Strip cuts can be made by removing the cross cut knives (c)cc slicer This machine will slice products up to 100mm in diameter. Anything larger will need a heavy duty machine, such as the Model Y slicer, or the G dicer with the cross cut and stripping knives removed The standard slice for the CC slicer is 3. 2mm thick but special parts are supplied to make thicker slices, such as onions at 4mm. One benefit of the CC slicer is that the knives are disposable, and this avoids honing and sharpening and, in effect, these knives are cheaper than the cost of sharpening those fitted to other machines and the cost of down-time. They will operate for 8-12hr with normal usage and are ideal when handling (d)oV Slicer This is a transverse slicer for fruit and vegetables which are not more than 70mm in diameter. Slice thickness is controlled by using a different slicing wheel which can be selected to give a slice length (or thickness ranging from 1.6mm to 32mm The slicer will not handle sticky products but can be used for leeks bananas, carrots,rhubarb, celery and asparagus. The feed must be controlled (e) Comtrol This is a cutter which will produce a wide range of cuts, and will comminute by flaking, slicing, shredding and dicing from 13mm down to microscopic sizes. It handles equally efficiently meat, fish, vegetables and fruit. It would have a special cation in comminuting soup ingredients down to a size suitable for instant or rapid rehydration (f)SC Scarifier This is used in dehydration specifically for slitting the skin or membrane of fresh peas. Peas are normally scarified before blanching, and
the product to the cutting parts. A 152mm diameter feed roll is fitted at the feed end of the belt to the knives. This flattens the vegetable before entering the knives and forces them into the cutting area. By the arrangement of the circular and cross-cut knives, the J cutter produces square cuts ranging from 6 by 6mm to 13 by 13mm, the thickness of this square being the thickness of the original product. For example a capsicum with flesh 4mm thick would emerge as a square flake 6 by 6 by 4mm or a larger square if the knives were adjusted. Strip cuts can be made by removing the cross cut knives. (c) CC Slicer This machine will slice products up to lOOmm in diameter. Anything larger will need a heavy duty machine, such as the Model Y slicer, or the G dicer with the cross cut and stripping knives removed. The standard slice for the CC slicer is 3.2mm thick but special parts are supplied to make thicker slices, such as onions at 4mm. One benefit of the CC slicer is that the knives are disposable, and this avoids honing and sharpening and, in effect, these knives are cheaper than the cost of sharpening those fitted to other machines and the cost of down-time. They will operate for 8-12hr with normal usage and are ideal when handling onions. (d) OV Slicer This is a transverse slicer for fruit and vegetables which are not more than 70mm in diameter. Slice thickness is controlled by using a different slicing wheel which can be selected to give a slice length (or thickness) ranging from 1.6mm to 32mm. The slicer will not handle sticky products but can be used for leeks, bananas, carrots, rhubarb, celery and asparagus. The feed must be controlled very evenly. (e) Comitrol This is a cutter which will produce a wide range of cuts, and will comminute by flaking, slicing, shredding and dicing from 13mm down to microscopic sizes. It handles equally efficiently meat, fish, vegetables and fruit. It would have a special application in comminuting soup ingredients down to a size suitable for instant or rapid rehydration. (f) SC Scarifier This is used in dehydration specifically for slitting the skin or membrane of fresh peas. Peas are normally scarified before blanching, and 42
are fed into the scarifier hopper from which they fall in a controlled stream between a rubber roller and a row of serrated wheels, revolving at a different speed. The peas pass through in a single layer so that each pea makes contact with the slitting wheel. The slit is made at a controlled depth -usually about 3mm as the peas pass between the rubber roller and the knives The purpose of scarifying is fully amplified in the Chapter 5 on the processing of vegetables(green peas) Bean Slicer Model w It is recommended in Chapter 5, on the subject of processing Green Beans, that slicing should be carried out after blanching, to avoid the loss of bean'seed'in the blanching water. Round pod beans are normally used for dehydration,and the Model w slicer gives a Julienne or French-style long cut rather than a transverse cut. the beans are fed by a belt incorporated in the machine to the cutting head, and kept in a straight line by oscillating parallel guides. The head consists of a circular knife spindle, a stripper plate assembly and a stationary knife The beans are cut lengthways by the circular knives, removed from between the knives by the stripper plate and guided on to a horizontal stationary knife at high speed, causing them to be cut through the centre at right angles to the cuts made previously by the circular knives A green bean snibbing line, cluster cutters and spill proof elevator
alp fed into the scarifier hopper from which they fall in a conhdled stream between a rubber roller and a row of serrated wheels, revolving at a different speed. The peas pass through in a single layer so that each pea makes contact with the slitting wheel. The slit is made at a contmlled depth - usually about 3mm as the peas pass between the rubber roller and the knives. The purpose of scarifying is fully amplified in the Chapter 5 on the ptucessing of vegetables (green peas). (g) Bean Slicer Model W It is recommended in Chapter 5, on the subject of processing Green Ekans, that slicing should be carried out after blanching, to avoid the loss of bean 'seed' in the blanching water. Round pod beans are normally used for dehydration, and the Model W slicer gives a Julienne or French-style long cut rather than a transverse cut. The beans alp fed by a belt incorporated in the machine to the cutting head, and kept in a straight line by oscillating parallel guides. The head consists of a circular knife spindle, a stripper plate assembly and a stationary knife. The beans a= cut lengthways by the cirrular knives, removed from between the knives by the stripper plate and guided on to a horizontal stationary knife at high speed, causing them to be cut through the centre at right angles to the cuts made previously by the circular knives. A grm ban snibbing line, cluster cutters and spill proof elevator 43
Left: Urschel Model G-A dicer, strip cutter and slicer Right: Urschel ModelJ9-A Left: Urschel Model RA-A for small to intermediate sized dices strip cuts and slices Right: Urschel Model wvF bean slicer
Left: Urschel Model G-A dicer, strip cutter and slicer Right: Urschel Model J9-A two dimensional dicer Left: Urschel Model RA-A for small to intermediate sized dices, strip cuts and slices Right: Urschel Model WVF bean slicer 4
〔h) Bean Snipper This is a revolving drum with perforated slots around the periphery. Knives are positioned to cut along the whole length of the drum, the cutting edge being set almost up to the drum surface The beans tumble around as they pass through the inside of the ylinder and, in course of travelling along its whole length, the ends project through the slots and are cut off by the knives Most modern snipers are continuous in action rather than batch fed and any unsnipped beans at the discharge end are returned to the feed end or, in the case of high capacity throughput, to a second machine in the line PEELERS There are basically four methods of peeling potatoes and root (1) Lye peeling )Steam peeling (3)Combination of heat and lye; (4)Abrasive peeling, either batch The dehydrator will have to decide which method suits his circumstances, and with due consideration to the effect of the method chosen on the effluent problem, which can, of course, be aggravated by one or other of these methods. Provided that the effluent problem has been taken care of, and that suitable treatment has been organised, the preference will usually lie between steam or lye peeling, and the advantages and disadvantages of both methods can be summarised as follows (1) Lye Peeling One of the main advantages is the relatively low capital cost of the equipment, as it is quite usual for lye peelers to be fabricated from mild steel, no particular advantage being obtained by using stainless steel. The design is basically simple, usually consisting of a perforated metal drum, with pockets into which the vegetables are fed, rotating in a bath of hot lye(sodium hydroxide) solution of 5-20 percent concentration, according to the peeling characteristics of the vegetables being handled Maintenance costs are low, as there are few moving parts in the machine The system is capable of a wide variation in peeling technique to suit any particular type of raw vegetable. Some processors use the thermal shock method of high concentration and temperature, with short immersion time, whereas others prefer a lower concentration of lye and longer dwell time. In some cases, wetting agents are used in the lye tank, to cut down the usage of
01) Bean Snipper This is a revolving drum with perforated slots around the periphery. Knives are positioned to cut along the whole length of the drum, the cutting edge being set almost up to the drum surface. The beans tumble around as they pass through the inside of the cylinder and, in course of travelling along its whole length, the ends project through the slots and are cut off by the knives. Most modem snippers are continuous in action rather than batch fed, and any unsnipped beans at the discharge end alr? returned to the feed end or, in the case of high capacity throughput, to a second machine in the line. PEELERS vegetables: There are basically four methods of peeling potatoes and root (1) Lye peeling; (2) Steam peeling; (3) Combination of heat and lye; (4) Abrasive peeling, either batch or continuous. The dehydrator will have to decide which method suits his circumstances, and with due consideration to the effect of the method chosen on the effluent problem, which can, of course, be aggravated by one or other of these methods. Provided that the effluent problem has been taken calr? of, and that suitable treatment has been organised, the preference will usually lie between steam or lye peeling, and the advantages and disadvantages of both methods can be summarised as follows: (1) Lye Peeling One of the main advantages is the relatively low capital cost of the equipment, as it is quite usual for lye peelers to be fabricated from mild steel, no particular advantage being obtained by using stainless steel. The design is basically simple, usually consisting of a perforated metal drum, with pockets into which the vegetables are fed, rotating in a bath of hot lye (sodium hydroxide) solution of 5-20 percent concentration, according to the peeling characteristics of the vegetables being handled. Maintenance costs are low, as there are few moving parts in the machine. The system is capable of a wide variation in peeling technique to suit any particular type of raw vegetable. Some processors use the thermal shock method of high concentration and temperature, with short immersion time, whereas others prefer a lower concentration of lye and longer dwell time. In some cases, wetting agents are used in the lye tank, to cut down the usage of 45
sodium hydroxide, or to make more effective use of the standard oncentration being used. Another technique to economise on lye is to allow the vegetables to pass from the peeler through a 'retaining reel, which is really a reel or rod washer with the water spray equipment remo dwell time in this reel, which can be 10-15min, according to its capacity, has the effect of extending the penetration effect of the lye on the skin of the regetable, thereby reducing the duty, and consequently the concentration of the lye in the peeler itself. From this reel, the vegetables pass normally to the washing process, which is either carried out in a second reel washer or in a rotating brush washer. On the debit side, the cost of sodium hydroxide is high, particularly when high concentrations have to be sustained. Also a considerable volume of water has to be used in subsequent washing, to arrest caustic burn and excessive penetration of the flesh and to remove all surface traces of lye. Again, some further chemical treatment may be necessary if peele potatoes or other vegetables have to be held in a surge hopper for any length f time prior to further processing. In these circumstances, it is usual to dose the surge hopper with 0.5 percent citric acid to neutralise any trace of alkalinity left by the lye treatment, and this, of course, adds to the cost of the operation Where lye peeling is undertaken, very special precautions must be taken to protect operating personnel against injury by contact with lye, and it is essential that the staff engaged in this department are supplied with heavy rubber boots, gloves and outer protective clothing, and goggles must worn at all times. Suitable warning notices relevant to the hazards must be displayed adjacent to the peeler, and first aid equipment to deal with caustic burns should always be close at ha Very rigid control of conditions of immersion time, temperature and concentration must be exercised, otherwise heavy leaching losses will occur, which will seriously affect the ratio and yield of end product. Leaching is the loss, by extraction, of soluble solids in vegetables, which is caused by over- immersion in either the lye peeling liquor or the blanching liquor. High temperatures are also a contributory factor to leaching in some cases (2)Flash Steam Peeling This method is extremely efficient, and has the advantage of creating fewer effluent disposal problems than other methods. The system utilising high pressure steam at 17atm ensures that even awkwardly shaped products are evenly peeled Steam at the pressure indicated heats the moisture under the skin of the vegetable in such a manner that, when pressure is reduced this moisture
sodium hydroxide, or to make more effective use of the standard concentration being used. Another technique to economise on lye is to allow the vegetables to pass from the peeler through a ‘retaining’ reel, which is really a reel or rod washer with the water spray equipment removed. The dwell time in this reel, which can be 10 - 15min, according to its capacity, has the effect of extending the penetration effect of the lye on the skin of the vegetable, thereby reducing the duty, and consequently the concentration of the lye in the peeler itself. From this reel, the vegetables pass normally to the washing process, which is either carried out in a second reel washer or in a rotating brush washer. On the debit side, the cost of sodium hydroxide is high, particularly when high concentrations have to be sustained. Also a considerable volume of water has to be used in subsequent washing, to amst caustic bum and excessive penetration of the flesh and to remove all surface traces of lye. Again, some further chemical treatment may be necessary if peeled potatoes or other vegetables have to be held in a surge hopper for any length of time prior to further processing. In these circumstances, it is usual to dose the surge hopper with 0.5 percent citric acid to neutralise any trace of alkalinity left by the lye treatment, and this, of course, adds to the cost of the operation. Where lye peeling is undertaken, very special precautions must be taken to protect operating personnel against injury by contact with lye, and it is essential that the staff engaged in this department are supplied with heavy rubber boots, gloves and outer protective clothing, and goggles must be worn at all times. Suitable warning notices relevant to the hazards must be displayed adjacent to the peeler, and first aid equipment to deal with caustic bums should always be close at hand. Very rigid control of conditions of immersion time, temperature and concentration must be exercised, otherwise heavy leaching losses will occur, which will seriously affect the ratio and yield of end product. Leaching is the loss, by extraction, of soluble solids in vegetables, which is caused by overimmersion in either the lye peeling liquor or the blanching liquor. High temperatures are also a contributory factor to leaching in some cases. (2) Flash Steam Peeling This method is extremely efficient, and has the advantage of creating fewer effluent disposal problems than other methods. The system utilising high pressure steam at 17atm ensures that even awkwardly shaped products are evenly peeled. Steam at the pressure indicated heats the moisture under the skin of the vegetable in such a manner that, when pressure is reduced this moisture 46
Table 3. 1 Relative peeling efficiency corundum Lye Peeling Peeling 3088ss 40509Los FLASH STEAM PEELING SYSTEMS TYPE 1002003004005508009501250 Pressure Vessel Volume litres 1002003004005508009501250 Door diameter. mm 200300300350350400400450 Support bearings, mm 75100100125125125 Steam connection. mm 100100125125125 Air connection. BSP.T Door seal Silicone rubber &mm dia. section Speed 6 rev. per min. Product per charge, Kg 3467100134200226333666 Steam Nominal consumptionkg/hr 100 200 300 400 600 800 1000 2000 Exhaust valve. mm 32 000 Electric 415V, 50hz, 3 phase(power), 110V, 50hz Single phase(control) Power Pressure vessel. Kw 1.51.51.51 3 Feed Conveyor, Kw 22222.222223 Discharge conveyor, Kw 222222222222223 Performance Typical example, Kg per hr1000200030004006000800010.00020.000 All capacities based on 30 cycles per hour
Table 3.1 Relative peeling efficiency FLASH STEAM PEELING SYSTEMS TYPE 100 200 300 400 550 800 950 1250 Pressure Vessel Volume, litres 100 200 300 400 550 800 950 1250 Door diameter, mm 200 300 300 350 350 400 400 450 Support bearings, mm 60 75 75 100 100 125 125 125 Steam connection, mm 60 75 75 100 100 125 125 125 Air connection, BSP.T. Door seal Silicone rubber, 8mm dia. section Speed 6 rev. per min. Product per charge, Kg 34 67 100 134 200 226 333 666 Steam Nominal consumptionKg/hr 100 200 300 400 600 800 1000 2000 Inlet valve, mm 25 40 40 50 50 75 75 75 Exhaust valve, mm 32 50 50 80 80 100 100 100 Electricity 25Opsi max WP (17 bar) Air, psi 80 80 80 80 80 80 80 80 415V, 50hz, 3 phase (power), 110V, 50hz Single phase (control) Power Pressure vessel, KW 1.5 1.5 1.5 1.5 3 3 3 4 Feed Conveyor, KW 2.2 2.2 2.2 2.2 2.2 3 3 3 Discharge conveyor, KW 2.2 2.2 2.2 2.2 2.2 2.2 2.2 3 Performance Typical example, Kg per hr 1000 2000 3000 4000 6000 8000 10,000 20,000 Ware potatoes All capacities based on 30 cycles per hour 47
flashes off, lifting the skin with it The final operation is to pass the product through a skin eliminator Peeling losses can be as low as 15 to 17 percent with ware(ie, table size) potatoes. See TABLE 3.1 Aflash steam peeler (3)Heat-Lye Peeling of lye and heat p America for potatoes. Tubers are first immersed in a very light lye solution and then pass through a gas fired infra red unit at 900oC. After the infra re treatment,most of the softened peel is removed by studded rubber rolls in a mechanical scrubber and final cleaning is effected in a brush washer which uses a minimal amount of water It is claimed that caustic soda usage is cut by 80 percent and water usage by over 90 percent, using this method. There are, relatively, no waste water problems, as the system uses only 15-45 litres per minute against 700- 1800 litres per minute in conventional lye peeling, and the waste peel can be onsolidated to a paste of approximately 15 percent solids which, after neutralising, can be used for animal feeding
flashes off, lifting the skin with it. Peeling losses can be as low as 15 to 17 percent with ware (ie, table size) potatoes. See TABLE 3.1. The final operation is to pass the product through a skin eliminator. A flash steam peeler (3) Heat-Lye Peeling The combined use of lye and heat peeling has been developed in America for potatoes. Tubers are first immersed in a very light lye solution, and then pass through a gas fired infra red unit at 900°C. After the infra red treatment, most of the softened peel is removed by studded rubber rolls in a mechanical scrubber, and final cleaning is effected in a brush washer, which uses a minimal amount of water. It is claimed that caustic soda usage is cut by 80 percent and water usage by over 90 percent, using this method. There are, relatively, no waste water problems, as the system uses only 15-45 litres per minute against 700- 1800 litres per minute in conventional lye peeling, and the waste peel can be consolidated to a paste of approximately 15 percent solids which, after neutralising, can be used for animal feeding. 48
