POTATO PRODUCTS

Abstract: A dry, cooked, heat sterilized, packaged potato product suitable for frying comprises potato pieces having a mois­ ture content of from 72 to 80% by weight produced by reducing the moisture content by from 2 to 10% by weight which have been surface treated prior to packaging with a combination of salt and a sugar preferably to apply from 0.1 to 0.4% of salt and 0.1 to 0.5% of sugar, in each case calculated on the weight of the pieces. The surface treat­ ment improves the flavour of the fried product and also enhances browning of the product on frying thereby reduc­ ing cooking time. A method for the production of the pro­ duct is also described.

Description: ?POTATO PRODUCTS This invention relates to potato products and especially to packaged pre-cooked potato pieces for frying. Potato pieces for frying are available in various forms, for example in the form of frozen chips for deep frying and oven chips. As both these products are frozen products they require, of course, to be stored in a freezer. In order to obviate this disadvantage and to produce a product that can be stored at room temperature, it has been proposed to package pre-cooked potato pieces in pouches in a sterile environment. In order to promote browning of the surface of such products on frying it has been proposed to partially pre-dry the pieces before packaging but even so the products require long cooking times and they are frequently considerably overcooked before they are adequately browned on the surface. This invention is based oh the observation that if packaged pre-cooked potato products for frying are surface treated with a mixture of salt and at least one sugar or sugar derivative before being sealed in the package and subjected to cooking and sterilization the product on frying achieves a crisp, browned outer surface with a far shorter frying time than is required for other products of similar nature. It also has an improved flavour after frying. This invention therefore provides a dry cooked heat sterilized packaged potato product for frying applications comprising partially dried potato pieces having a moisture content of from 72 to 80% by weight, preferably 72.5 to 77% by weight-that have been surface treated prior to packaging with a combination of salt and at least one sugar. The invention also provides a process for the production of such potato products which comprises treating potato pieces with salt and at least one sugar either separately or in admixture, partially drying the potato pieces to a moisture content of from 72 to 80% by weight, preferably from 72.5 to 77% by weight by reducing the water content by from 2 to 10% on a w/w basis, packing the pieces in a package, sealing the package, and sterilizing the package and product and, if the product is not already cooked, cooking the product. As sugars that can be used in the operation of the invention there may be mentioned, for example, reducing sugars, especially monosaccharides such as Dand L-glucose, fructose,lactose and the like and di- and polysaccharides that break down to form reducing sugars during sterilizing and/or cooking of the product or during the initial stages of the frying operation. Sucrose may be mentioned as an example of such a dia saccharide. The sugar controls browning of the productduring frying but also has an effect on the flavour of the product, especially its sweetness. Sucrose for example provides relatively low rates of browning of the product but significantly changes the sweetness of the product. On the other hand dextrose, fructose and the like give lower changes of sweetness but produce very much higher rates of browning while lactose produces virtually no increase in sweetness but has very good browning properties. By using mixtures of sugars such as, for example mixtures of sucrose and lactose or glucose and lactose a ready control of the flavour and browning properties of the product can be'achieved so that even with changes of the type of potato or of changes in flavour within a given type of potato throughout the year it is possible to achieve a consistent product. The salt that is added is primarily used as a flavouring agent and to this end normally sodium chloride will be used. It is however possible to use other flavouring salts such as, for example, potassium chloride or flavour enhancing salts such as mono sodium glutamate may be used either instead of or together with a flavouring salt. The The treatment with salt and sugar(s) is most conveniently carried out by dipping the potato pieces in a solution of salt and sugar(s) in the desired proportions. It is however possible to spray the pieces with a solution of salt and sugar(s) or even to dust dry salt and sugar(s) onto the pieces. The surface treatment normally results in the application to the surface of the potato pieces of salt in an amount of from 0.1 to 0.4g and sugar(s) in an amount of from 0.1 to 0.5% by weight, calculated on the weight of the pieces. This can be achieved, for example, by dipping the pieces in a solution containing 1 to 8% by weight of salt and 0.5 to 4% by weight of sugars The.pieces may be immersed in the solution for a period from 10 to 120 seconds the longer immersion times being used at the lower concentrations of salt and sugar(s). Before they are subjected to the drying treatment the pieces will normally be blanched to inhibit enzyme activity and to inhibit oxidation, greying and browning reactions. A typicalblanchingprocess comprises immersing the pieces in hot water containing acid sodium pyrophosphate as a greying inhibitor and sodium metabisulphite as a browning inhibitor. This blanching operation can also cause partial leaching of sugars from high ssar -potatoes thus giving a more uniform colour formation during frying. The blanching solution may contain for example 0.5 to 1% by weight of acid sodium pyrophosphate and approximately 0.05% of sodium metabi sulphte, While the blanching conditions are not critical a typical blanching operation may be carried out by immersing the pieces in hot water at from 84 to 90 0C for a period of from 5 to 10 minutes. The amount of water removed from the product in the partial drying step is crucial to the quality of the product. If too much water is removed from the product darkening of the product occurs and off flavours are introduced. If too little water is removed the time required to brown the product becomes very much longer, there is a high weight loss on frying and the water that is removed on frying-tends to degrade the oil or fat in which the product is fried. The potato pieces are packaged in air tight packages in which they can be sealed either under vacuum or under an inert gas atmosphere at reduced pressure and in which they can be heated under conditions satisfactory to precook the potato pieces and also to sterilize the products. The packages must be sealable and when sealed must be air and moisture tight. The packaging material may, for example, comprise metal, for example, aluminium, foil laminated to heat sealable thermoplastics film or it may comprise an oxygen-barrier polymeric film, such as polyvinyl dichloride or ethyl vinyl alcohol film laminated to heat sealable thermoplastics film. Preferably a thermoplastics film is laminated on each face of the barrier film whether it be metal foil or a polymeric film. Among the potato 'products that can be produced are potato chips (french fries), or roast potatoes, a product which has not previously been satisfactorily produced in packaged form. On cooking, by frying, the surface of the pieces browns very much more readily than is customarily the case with products of this sort and generally frying times of only about 2 to 5 minutes are required. The products therefore do not become grossly overcooked during frying and therefore have a very much better taste and texture than other products of this type. The following Examples illustrate the invention. EXAMPLE 1 Potatoes having a moisture content of approximately 80% by weight were peeled and chipped and slivers and nubbins were removed. The potato chips were then subjected to a hot water blanch at 870C + 20C for 7 minutes. The blanch water contained 0.5% by weight of acid sodium pyrophosphate and 0.05% of sodium metabisulphite. The blanched chips were then rinsed in water at 2000 to cool the chips and to remove surplus starch and the constituents of the blanching solution. The ships were then surface treated by dipping them into a solution at ambient temperature containing 4% salt and 1% sucrose for 40 seconds. After draining the chips were dried to reduce the water content to approximately 75 to 78% w/w using a hot-air belt drier. On leaving the drier the chips were cooled. The chips were then filled into pouches comprising aluminium foil laminated on each side to thermoplastic films. The pouch was evacuated to approximately 750 mm of mercury vacuum and then backflushed with nitrogen to 500 mm of mercury vacuum and sealed using impulse or constant temperature sealing jaws. The sealed packages were then placed in an autoclave and heated for 40 minutes at an autoclave temperature of 121 C under a pressure of 11 to 3 bars to give a commercially sterile product. The pouches were cooled in the autoclave while maintaining an over pressure of 1 to 2 bars to prevent expansion of the pouches. EXAMPLES 2 TO 6 EMI7.1 <tb> <SEP> Potato <tb> Example <SEP> Potato <SEP> Moisture <SEP> Post <SEP> Drying <SEP> Treatment <SEP> Solution <tb> <SEP> No. <SEP> Variety <SEP> Content <SEP> Moisture <SEP> Content <SEP> Strength <SEP> w/w <tb> <SEP> w/w <SEP> w/w <tb> <SEP> 2 <SEP> Cyprus <SEP> 4% <SEP> Sodium <SEP> Chloride <tb> <SEP> Spunta <SEP> 83% <SEP> 77.3% <SEP> 1% <SEP> Sucrose <tb> <SEP> 2% <SEP> Glucose <SEP> D <tb> <SEP> 3 <SEP> English <SEP> 4% <SEP> Sodium <SEP> Chloride <tb> <SEP> Maris <SEP> 80% <SEP> 75% <SEP> 1% <SEP> Sucrose <tb> <SEP> Piper <SEP> 1% <SEP> Lactose <tb> <SEP> 4 <SEP> Dutch <SEP> . <SEP> 3% <SEP> Sodium <SEP> Chloride <tb> <SEP> Bintje <SEP> 78% <SEP> 73.8% <SEP> 1.5% <SEP> Mono <SEP> Sodium <SEP> Glutamate <SEP> <tb> <SEP> 1% <SEP> Sucrose <tb> <SEP> % <SEP> Fructose <SEP> <tb> <SEP> 5 <SEP> English <SEP> 2% <SEP> Potassium <SEP> Chloride <tb> <SEP> King <SEP> 77% <SEP> 73.3% <SEP> 2% <SEP> Sodium <SEP> Chloride <tb> <SEP> Edwards <SEP> 1% <SEP> Glucose <tb> <SEP> > <SEP> 1% <SEP> Lactose <tb> <SEP> 6 <SEP> English <tb> <SEP> Records <SEP> 76% <SEP> 72.7% <SEP> 3% <SEP> Sodium <SEP> Chloride <tb> <SEP> 0.01% <SEP> Disodium <SEP> 5 <SEP> Inosinate <tb> <SEP> 0.01% <SEP> Disodium <SEP> 5 <SEP> Guanylate <tb> <SEP> 29 <SEP> Glucose <tb> The samples were treated either by spraying the chips or dipping the chips with a solution of the above salts and sugars for 30 seconds to 60 seconds. Apart from the conditions specified above the general process conditions and apparatus were as described in Example 1. After sterilization the products were deep fat fried in fat or oil at 17500 to 185C and gave a golden brown highly acceptable chip in 2 to 3 minutes.

Claims: CLAIMS: 1. A dry, cooked, heat sterilized, packaged potato product for frying comprising partially dried potato pieces having a moisture content of from 72 to 80% preferably from 72.5 to 77% by weight that have been surface treated prior to packaging with a combination of salt and at least one sugar. 2. A potato product according to claim 1, the surface of which has been treated with an amount of salt within the range of from 0.1 to 0.4% by weight and with sugar(s) in an amount of from 0.1 to 0.5% by weight, in each case calculated on the weight of the pieces. 3. A potato product according to claim 1 or claim 2, wherein the salt is sodium chloride, potassium chloride or mono sodium glutamate. 4. A potato product according to any one of claims 1 to 3, wherein the sugar is a reducing sugar or a di- or poly-saccharide that breaks down on heating to form a reducing sugar. 5. A potato product according to claim 4, wherein the sugar is sucrose, D or L glucose, fructose or lactose or a mixture of any two or more thereof. 6. A method of making a dry, cooked, heat sterilized, packaged potato product which comprises treating potato pieces with salt and at least one sugar before they are placed in a package in which they are sealed and sterilized and, if not-already cooked, are cooked, the potato pieces being partially dried to a moisture content of from 72 to 80% preferably from 72.5 to 77% by weight by reducing the moisture content by from 2 to 10% on a w/w basis. 7. A method according to claim 6, wherein the treatment with salt and sugar(s) is carried out by dipping the potato pieces in a solution of salt and sugar(s). 8. A method according to claim 6, wherein the treatment with salt and sugar(s) is carried out by dipping the potato pieces sequentially in a solution of salt and a solution of sugar. 9. A method according to claim 7 or claim 8, wherein the treatment solution(s) contain 1 to 8% by weight of salt and 0.5 to 4% by weight of sugar(s). 10. A method according to any. one of claims 7 to 9, whereinsthe potato pieces are immersed in the solution for a period of from 10 to 120 seconds. 11. A method according to any one of claims 6 to 10, wherein the surface treatment is such as to apply to the surface of the potato pieces salt in an amount of from 0.1 to 0.4% and sugar(s) in an amount of from 0.1 to 0.5% by weight calculated on the weight of the pieces. 12. A method according to any one of claims 6 to 11, wherein the potato pieces are blanched, preferably in a hot aqueous solution containing acid sodium pyrophosphate and sodium metabisulphite, before they are subjected to the surface treatment.

Inventors: ATHERTON, JOHN, HAWKINS, MICHAEL JOHN, SMITH, PHILIP GRAHAME
Applicants: MARS U.K. LIMITED
Application year: 1982
Main classification: A23L1
IPC codes: A23L1