GB2221374A - Method of making an edible potato dough sheet - Google Patents

Description

-1A Method of Making a Potato Dough Edible Sheet This invention relates to

a method of making an edible sheet from potato dough, which can be presented in the form of disks or other shapes which are dimensionally stable until eventual cooking in hot oil or otherwise.

The main difficulty in the production of conventional fried potato products, such as chips or crisps, lies in the seasonal variation in the supply of raw material of suitable quality. Not every potato variety is apt for frying, nor are all climates or potato-producing areas suitable for growing potatoes for frying purposes, as such potatoes require a low content of reductor sugars and a high content of dry matter. On the othei hand there are no potato crops during the winter, and the friedpotato product manufacturer has to obtain his supply from stored potatoes.

Storage of potatoes for frying is subject to critical demands as regards the quality of the finished product; these demands have not yet been completely resolved.

To prevent potato decay and attack by bacteria and fungus, potatoes are treated with bactericides and fungicides, and stored at low temparatures. This is usually sufficient for potatoes destined for human consumption to stay in good condition until the new crop arrives, but the low temparature causes concentration of reductor sugars in the potato, which renders it unsuitable for frying as the sugars produce a brown colour.

To prevent the formation of reductor sugars, the only known method is storage at a higher temparature, between 18 and 20' C.; however microbiological attack and sprouting are encouraged by this.

Faced with this dilemma, some intermediate compromise is often adopted which does not altogether prevent any of these problems, and it is well known that during winter and spring, potatoes are always more or less 2 '1. 2 13 7 4 -2affected by darkening, spots and bores caused by micro-organisms.

Another drawback in the direct processing of the potato tuber is the variety of sizes which makes it necessary to classify them before hand, which reduces the desirability of those of marginal size to prevent difficulties during automatic packing, such as weight differences,volume inequality and losses in packing caused by pieces being caught in the sealing procedure.

An object of this invention is to provide manufacturers of snack foods with ready-to-fry potato sheets, allowing for a two year storage period between production and the eventual cooking operation before packaging.

The invention also seeks homogenisation of product quality, offering constant appearance, size and flavour to consumers, irrespective of variations in potato quality through the different seasons of the year, and completely eliminating faults caused by biological alterations and by attacks from micro-organisms or insects. A further object of the invention is to provide the trade with a means for the regulation of their output and pricing independantly of variations arising from seasonal potato price variations. 20 Fried potato products, such as chips or crisps, are made by washing, peeling slicing and frying potatoes in a continuous procedure. In other words, by industrialising the commonly used domestic method. This process, therefore is completely different from the starting point of this invention, which begins with making a potato dough which is then treated to obtain a stable sheet of dough.

The making of products from a dough is not novel in itself, there already exist extruded products in the market which start from a dough and -3are then fried in a continuous process. An example of this may be socalled 'churros' or lpapadoms' and similar products, but these products must be fried immediately after preparing the dough. Other non-snack productJalso start from flour doughs, these are the so- called pastas or extruded doughs, such apspa .ietti, canelonni, lasagna, noodles, etc.

These methods are als different from that of this invention, since there is no final frying of the product and because the flours employed for them are uncooked whereas the raw materials used in the present invention are precooked.

Accordingly, the invention provides a method comprising first making an edible dough consisting of treated potato flour, including also potato starches and other additives such as salt, and forming a stampable sheet, and cutting this sheet into shaped portions which may be stored for periods of over two years, without losing their food value, flavour or appearance, and eventually heat treating the pieces in oil, at a temparature of e.g. between 170' and 230' C.

The above problems and disadvantages are substantially eliminated by the present invention, -which provides the manufacturer with a potato dough sheet, of a uniform size, constant organoleptic quality, a price which is not subject to seasonal fluctuations and a guaranteed minimum storage time of two years before eventual frying.

An additional advantage is that less oil is absorbed during the frying process.

The conventional fried potato products (chips or crisps) have an oil content which ranges between 35 and 45%, while the product of this invention has from 20 to 30% less oil after frying, with consequent dietetic advantages.

A preferred method according to the present invention will now be described by way of example.

The starting material is fresh newly picked potatoes, of the most suitable variety for frying. These potatoes are then washed, peeled, freed from impurities, sliced, boiled in water, kneaded, dehydrated in a fluidized bed or other device.,_and finally sieved.

Thus processed, with a humidity of 5 to 10% when rehydrated, the potato is transformed into a dough which retains the organoleptic properties of the fresh boiled potato. This cooked dehydrated potato dough is then mixed, as will be shown below, with potato starch which has been previously submitted to a phosphating treatment:., then cooked and dehydrated.

The porosity and texture of the finished product are controlled through the balance between the native and added treated starches.

is An ideal formula for these raw materials would be; - precooked dehydrared potato flour 40-80%, preferrably 60% - modified potato starch 5-25%_, preferrably 15% - native potato starch 15-40%, preferrably 25%.

This is not a limitative formula. For example, part of the potato flour may be replaced with precooked cereal flours, and part of the potato starch, either native or modified or both, may be replaced with equivalent wheat, maize or other starches.

An alternative formula for example might be:

- precooked dehydrated potato flour 40% - precooked wheat flour 20% modified potato starch 15% 15% 15% native potato starch native maize starch The preferred process consists of the following steps:- mixing of dry ingredients - addition of water to obtain dough humidity of 25-40% extrusion rolling the sheet stamping shaped portions from the sheet drying the pieces packing the pieces storing - eventual heat treatment The mixing is done with a double screw helicoidal mixer,in a hopper. When the dough leaves the hopper, it is sieved to ensure removal of any foreign bodies, and it is then transported to the water addition step.

The addition of water is done by spraying upstream from the flour within a knife or hammer tamper.

The extrusion press has a continuous element which transfers the moist dough onto a variable speed endless belt, whose speed is regulated in accordance with the compression required for the homogenous compacting of the dough.

The heat generated during the compression must be dissipated by means of a suitable cooling system which allows the dough to maintain a temparature between 30 and 60' C. to prevent excessive gelling and consequent increase in dough viscosity, which would in turn generate more heat through friction.

The douffi leaves the extruder in the form of a sheet, 1 to 3 mm.

thick, and is sent to a roller train which reduces the thickness to 0.5 1 mm.

The sheet is stamped out to form ovals or other shapes while still in the roller train, and the excess dough is returned to the extruder to avoid waste. Drying is done by controlling air flow and humidity, to acheive a final humidity of 10 to 15%.

The product is then put in containers to protect it against changes in environmental humidity, it is then stored and distributed for eventual final treatment. This typical final treatment is frying in hot oil at a temparature of 170' to 210% to acheive a residual humidity of under 3%.

During the frying process, the product undergoes an expansion of around 10-20%, resulting in a golden crisp textured sheet, whose flavour is that of fried potatoes.

The preceding description is beleived to be sufficient to enable a person skilled in the relevant art to be able to understand and carry

Claims (14)

1. out the invention. The materials, shape, size and arrangement of the

   method are susceptible to variation within the scope of the appended Claims, and the terms used in this description are to be understood broadly and not in a limitative sense.

   -7 Claims 1. A method of making an edible sheet of potato dough, from fresh newly picked and properly washed potatoes, with all impurities removed, which are sliced, boiled in water, kneeded and dehydrated, then mixed with natural potato starch and potato starch which has been previously 5 submitted to a phosphating treatment, cooked and dehydrated.
2. 2. A method according to Claim 1 wherein wheat, maize or other cereal starches are'also added, as well as salt in suitable amounts, flavour enhancers, dressings, aromas and vitamin concentrates.
3. 3. A method according to Claim 1 or 2, including a first phase of dry mixing of ingredients, after which water is added to obtain a dough humidity between 25 and 40%, extruding the dough, and rolling it followed by stamping out pieces, and finally drying, packing and storing the product, followe by eventual heat treatment of the product.
4. 4. A method according to any preceding Claim, including a mixing step performed by a twin helicoidal mixer inside a hopper, to remove foreign bodies, and transporting the dough to a water sprayer.
5. 5. A method according to any preceding Claim, comprising adding water by spraying upstream from the flour, in a knife or hammer tamper.
6. 6. A method according to Claim 1 wherein a continuous extrusion phase in an extruder transfers the dough onto a variable speed endless belt, whose speed is regulated in accordance with the compression required for homogenous compression of the dough.
7. 7, A method according to any one of Claims 1 to 6, wherein the dough is kept in a temparature range between 30 and 60% to prevent excess gelling and consequent dough viscosity, and suitable cooling means are provided to acheive this, to disipate the compression generated heat.

   :p.
8. 8. A method according to any one of Claims 1 to 6 wherein the dough leaves the extruder in sheet form, with a thickness between 1 and 3 mm. and is routed to a roller train to further reduce its thickness to between 0.5 and 1 mm.
9. 9. A method according to any preceding Claim wherein stamping out is performed in the roller train as part of the rolling procedure, and produces ovals or other shapes, the excess dough being returned to the extruder to avoid waste.
10. 10. A method according to any preceding-Claim, including drying the dough with temparature and humidity controlled air, to acheive a final humidity range between 10 and 15%.
11. 11. A method according to any preceding claim including a final heat treatment step, comprising frying the sheet at a temparature between 170 and 210T. to acheive a residual humidity of under 3%, the dough expanding between 10 and 20%.
12. 12. A method according to any preceding Claim wherein precooked and dehydrated potato flour is used as raw material, in a percentage ranging from 40 and 80%, preferrably 80%, modified potato starch in a percentage range of 5 to 25%, preferrably 15%, and from 15 to 40% of native potato 20 starch, preferrably 25%.
13. 13. A method according to any one of Claims 1 to 11, - ^herein 40% of precooked dehydrated potato flour, 20% precooked iheat flour, 15% modified potato starch, 15% native potato starch and 15% native corn starch are used.
14. 14. A method of making an edible potato dough sheet, substantially as hereinbefore described, with reference to the particular examples given.

    Published 1990 at The Patent Office.StateHouse.66 71 I.LghHolborn, LondonWC1R4TP.Purther copies maybe obtainedfrom The Patent Office. Sales Branch. St Mary Cray. Orpington, Kent BR5 3RD. Printed by Multiplex techniques itd, St mary Cray, Kent, Con. 1187 1