5 Dehydration of otto Products Potato granules Potato granules are more usually commercially designated as Instant Potato or Potato Mash Powder. This product was first manufactured in the UK,on a commercial scale, some 55 years ago. As the name implies, precooked potatoes are dehydrated into granular form and, when hot water is added, they revert almost instantly to cooked mashed potato. This product has been widely developed as a convenience food in America and Europe, and is almost certainly the most popular form of dehydrated potato on the market today. It features extensively in snack foods There are several methods of producing granules but the generally accepted commercial method is the 'add-back process. Several improvements have been made in the manufacturing processes since World War Il, and some of these are referred to in british Patents No 683, 604(1952) and No 740, 711 (1955). The basic process goes back to, and is described in, earlier Patents-No, 496423. No, 525.043 and No. 601,152 The following description of the process explains the basic commerci add-back method but makes no reference in detail to the refinements and mprovements, introduced in recent times, by individual processors, many f which were originally patented
5 Dehydration of Potato Products Potato Granules Potato granules are more usually commercially designated as Instant Potato or Potato Mash Powder. This product was first manufactured in the UK, on a commercial scale, some 55 years ago. As the name implies, precooked potatoes are dehydrated into granular form and, when hot water is added, they revert almost instantly to cooked mashed potato. This product has been widely developed as a convenience food in America and Europe, and is almost certainly the most popular forin of dehydrated potato on the market today. It features extensively in snack foods. There are several methods of producing granules but the generally accepted commercial method is the 'add-back' process. Several improvements have been made in the manufacturing processes since World War 11, and some of these are referred to in British Patents No.683,604 (1952) and N0.740~711 (1955). The basic process goes back to, and is described in, earlier Patents - No.496,423, No.525,043 and N0.601~152. The following description of the process explains the basic commercial add-back method but makes no reference in detail to the refinements and improvements, introduced in recent times, by individual pmcessors, many of which were originally patented. I05
Flow Sheet Feed to Line Dry Cleaning Destoner washer Peeling Skin elimination Washing nspection- Trimming Slabbing(Slicing) Mashing-Mixing Add- Back mix Suppl Additives Granulating -Conditioning 1.5mr 65% add-back granules Secondary Drying(35%)by bulk Final Sieving through 250 micro Overtails return Primary Packing to mixer Flushing in poly-lined sacks
Flow Sheet Feed to Line I Dry Cleaning I Destoner Washer I Peeling I Skin Elimination I Washing I Inspection - Trimming I Slabbing (Slicing) I I Mashing - Mixing I Add - Back Mix I Sulphiting + Additives I Granulating - Conditioning I + 1.5mm rejected I to mixer by bulk Secondary Drying (35%) by bulk I Final Sieving through cooking kreeningd 65% add-back granules 250 micron sieve I 7 Overtails return Primary Packing to mixer Nitrogen Flushing I Secondary Packing in poly-lined sacks I06
A Lockwood self feed hopper in to which potatoes are being Varieties of Potato Suitable for granules The main requirements are(I)high solids content, (2) low reducing sugars,(3)freedom from aftercooking darkening, 4) immunity to wart diseases, and () shalloweyes In America and the UK, the preference is for white fleshed varieties, whereas in Western Europe, cream and yellow fleshed potatoes are more popular The following varieties are, therefore, in general commercial use for this process USA: Russet Burbank Katahdin Kennebec Cobbler ppewa
A Lockwood self feed hopper in to which potatoes are being tipped from a swivel head fork lift truck Varieties of Potato Suitable for Granules The main requirements are (1) high solids content, (2) low reducing sugars, (3) freedom from aftercooking darkening, (4) immunity to wart diseases, and (5) shallow eyes. In America and the UK, the preference is for white fleshed varieties, whereas in Western Europe, cream and yellow fleshed potatoes are more popular. The following varieties are, therefore, in general commercial use for this process. USA: Russet Burbank, Katahdin, Kennebec, Cobbler, Chippewa I07
Aran Comet, Aran pilot Home guard Estim Pentland Javelin, Pentland Crown Maris Peer, Cara Maris Piper, Pentland Dell, Europe: Bintje, Iris, Lenina (West and East)Record, Uren, Wilja, Desiree PROCESS ortant factor to be observed at all points of processing is Prevention of cell rupture in the raw material. Every individual cell that damaged in peeling, cooking, granulating or drying will release free starch, which will mitigate against satisfactory reconstitution, and will produce a sticky gelatinous mass instead of a light fluffy mashed potato Peeling should be by lye or the steam method, and the potatoes should be well sprayed with cold water afterwards. This can be done in a rod washer, or preferably in a brush washer as described in the chapter on preparation plant. Batch abrasive peelers are wasteful, and tend to create the very conditions of cell damage which should be avoided. More recently developed continuous abrasive peelers, with sophisticated control of the depth of peeling, may well meet the requirements of minimal cell damage, therefore the processor has a reasonably wide choice of equipment for this part of the process, but Flash Steam Peeling is preferred From the peeler and washing plant, the potatoes pass over an inspection belt where they are trimmed. With average quality raw material, ten women at the trimming belt should handle 16 tons in eight hours. At the end of the trimming and inspection table, the small to medium size potatoes o straight to the cooker whilst tubers of 44mm upwards are diverted to a slicing machine for slabbing into 20mm slices before returning to the main flow into the cooker. If required, the trimmed and sliced potatoes can be delivered into a surge tank prior to cooking; this has the effect of removing surface starch, and also provides buffer storage to keep the line running where there are breaks in the preceding pro ocess for some reason Cooking, in continuous cookers, may be in atmospheric steam for 45-60 min, or alternatively the potatoes may be partly cooked in hot water, cooled and then transferred to the steam cooker( Cording and willard method: 1955) From the cooker, which is usually a rectangular steam cabinet with a tainless steel mesh conveyor belt, the potatoes now emerge, thoroughly but not overcooked, and fall into a paddle mixer. This is normally of the U trough-type, with a rotating shaft fitted with T-shaped paddles at intervals
UK: Aran Comet, Aran Pilot, Home Guard, Estima, Pentland Javelin, Pentland Crown, Maris Peer, Cara, Maris Piper, Pentland Dell, (West and East) Record, Uren, Wilja, Desiree. Europe: Bintje, Iris, Lenino PROCESS The important factor to be observed at all points of processing is the prevention of cell rupture in the raw material. Every individual cell that is damaged in peeling, cooking, granulating or drying will release free starch, which will mitigate against satisfactory reconstitution, and will produce a sticky gelatinous mass instead of a light fluffy mashed potato. Peeling should be by lye or the steam method, and the potatoes should be well sprayed with cold water afterwards. This can be done in a rod washer, or preferably in a brush washer as described in the chapter on preparation plant. Batch abrasive peelers are wasteful, and tend to create the very conditions of cell damage which should be avoided. More recently developed continuous abrasive peelers, with sophisticated control of the depth of peeling, may well meet the requirements of minimal cell damage, therefore the processor has a reasonably wide choice of equipment for this part of the process, but Flash Steam Peeling is preferred. From the peeler and washing plant, the potatoes pass over an inspection belt where they are trimmed. With average quality raw material, ten women at the trimming belt should handle 16 tons in eight hours. At the end of the trimming and inspection table, the small to medium size potatoes go straight to the cooker, whilst tubers of 44mm upwards are diverted to a slicing machine for slabbing into 20mm slices before returning to the main flow into the cooker. If required, the trimmed and sliced potatoes can be delivered into a surge tank prior to cooking; this has the effect of removing surface starch, and also provides buffer storage to keep the line running where there are breaks in the preceding process for some reason or another. Cooking, in continuous cookers, may be in atmospheric steam for 45-60 min, or alternatively the potatoes may be partly cooked in hot water, cooled and then transferred to the steam cooker (Cording and Willard method: 1955). From the cooker, which is usually a rectangular steam cabinet with a stainless steel mesh conveyor belt, the potatoes now emerge, thoroughly but not overcooked, and fall into a paddle mixer. This is normally of the U trough-type, with a rotating shaft fitted with T-shaped paddles at intervals I08
along the length. The angle of the paddles to the line of the shaft is variable so that the flow of material can be accelerated or decelerated, as may be required, to thoroughly mix the product Mashing, and mixing in the add-back granules or'seed powder at this point must be gentle to avoid cell rupture, and the speed of the mixer is critical. The seed powder is continuously fed into the mixer at the point where the cooked potatoes enter, at a rate in excess, by weight, of the potatoes The average proportions might be 35 percent potato to 65 percent seed powder but this can only be established by practice, and will vary according to the solid matter in the raw potato, and, conversely, the moisture content of the seed. The ultimate objective is to obtain a blend with 35-40 percent moisture; the arrangement whereby the seed powder is available continuously at the mixer is described later The blend of cooked potato and add-back seed fills up the trough mixer, and is then allowed to fall over a weir, through an aperture in the end plate, into a second mixer of longer but shallower proportions. The purpose of this second mixer is to extend the mixing period, at the same time allowing the blend to cool as it travels along the trough. As stated before, the rate of travel is controlled by the of the paddles, and thor will take 25-35 min Sulphite and other additives, which may be required, are added to the blend by a suitable metering device, during the mixing Process No general rule can be applied as to the additives, as Food Laws differ from country to country, and the processor must familiarise himself with what is permitted, and what is not, in his own particular market. Additiv may include sodium metabisulphite, acid sodium pyrophosphate monostearates, anti-oxidants, flavourings and milk powde Sulphur Pyrophosphate, anti-oxidants, and sometimes milk powder are mixed with potato granules to make a ' master mix whereby the metering into the mash can be more accurately gauged and, by dilution, can be assimulated more evenly than small quantities of separate ingredient Glycerol monostearate in solution is metered in At the end of the second mixer, the blend again falls over a weir and passes to a conditioning bin, where the material cools to about 24"C in our wo bins are normally used, one being filled whilst the other is conditioning. This conditioning is a most important stage in the process, as it assists granulation and retrogradation of the starch From the bottom of the conditioning bin, the blend feeds into the first stage of drying. The primary dryer can be either (a)a pneumatic ring dryer, or(b)a thermal venturi dryer, both of which were described in Chapter IV a suitable feeding arrangement is required for the particular type of dryer
along the length. The angle of the paddles to the line of the shaft is variable, so that the flow of material can be accelerated or decelerated, as may be required, to thoroughly mix the product. Mashing, and mixing in the add-back granules or ‘seed’ powder at this point must be gentle to avoid cell rupture, and the speed of the mixer is critical. The seed powder is continuously fed into the mixer at the point where the cooked potatoes enter, at a rate in excess, by weight, of the potatoes. The average proportions might be 35 percent potato to 65 percent seed powder but this can only be established by practice, and will vary according to the solid matter in the raw potato, and, conversely the moisture content of the seed. The ultimate objective is to obtain a blend with 35-40 percent moisture; the arrangement whereby the seed powder is available continuously at the mixer is described later. The blend of cooked potato and add-back seed fills up the trough mixer, and is then allowed to fall over a weir, through an aperture in the endplate, into a second mixer of longer but shallower proportions. The purpose of this second mixer is to extend the mixing period, at the same time allowing the blend to cool as it travels along the trough. As stated before, the rate of travel is controlled by the angle of the paddles, and thorough granulation will take 25-35 min. Sulphite and other additives, which may be required, are added to the blend by a suitable metering device, during the mixing process. No general rule can be applied as to the additives, as Food Laws differ from country to country, and the processor must familiarise himself with what is permitted, and what is not, in his own particular market. Additives may include sodium metabisulphite, acid sodium pyrophosphate, monostearates, anti-oxidants, flavourings and milk powder. Sulphur Pyrophosphate, anti-oxidants, and sometimes milk powder are mixed with potato granules to make a ’master mix‘ whereby the metering into the mash can be more accurately gauged and, by dilution, can be assimulated more evenly than small quantities of separate ingredients. Glycerol monostearate in solution is metered in. At the end of the second mixer, the blend again falls over a weir and passes to a conditioning bin, where the material cools to about 24°C in an hour. Two bins are normally used, one being filled whilst the other is ‘conditioning’. This conditioning is a most important stage in the process, as it assists granulation and retrogradation of the starch. From the bottom of the conditioning bin, the blend feeds into the first stage of drying. The primary dryer can be either (a) a pneumatic ring dryer, or (b) a thermal venturi dryer, both of which were described in Chapter IV. A suitable feeding arrangement is required for the particular type of dryer I09