AU6815400A - Portion bag containing pre-deep-fried fries - Google Patents

Description

WO 01/21014 PCT/CHOO/00489 DESCRIPTION TITLE Portion-size bag containing prefried potato sticks 5 TECHNICAL FIELD The present invention relates to a process for preparing a portion-size bag and a portion-size bag containing a portion, packaged therein, of prefried 10 potato sticks, from which, by later rebaking without repeated deep-frying, ready-to-eat French-fried potatoes can be obtained. PRIOR ART 15 French-fried potatoes are one of the most important accompaniments in catering, but also, to an increasing extent, also in domestic cooking. Since their production, if they are made from raw potatoes, is 20 time- and material-consuming and is no longer reconcilable with the current conceptions of up to date and rapid cuisine, French-fried potatoes are increasingly being produced on an industrial scale in a preprepared form and supplied in this manner to 25 catering enterprises and households. Preparation of the potato sticks here can consist solely of peeling and subsequently slicing the potatoes into sticks, but it can also comprise a prefrying step. French-fried potatoes which are prefried in such a manner are then 30 either frozen, possibly even in a shock-freezing process, packaged and stored in a bag, or else packaged in the unfrozen state, generally under a protecting gas atmosphere, and kept at a typical refrigerator temperature of approximately 4 0 C, or, in the case of 35 certain products, at least at refrigerator temperature. Whereas prefried potato sticks have a very long shelf life at freezer temperatures, those which are kept at refrigerator temperature are usually stored only for a WO 01/21014 - 2 - PCT/CHOO/00489 time of at most three to a maximum of four weeks. Such French-fried potatoes can be designed to be briefly deep-fried again on the part of the final consumer, or they can be designed in such a manner that they only 5 need to be heated in an oven and rebaked on the part of the final consumer. Whereas French fries designed for post-frying generally have a water content of more than 75%, those for rebaking in an oven usually have a water content of 65% and an oil content of 7-8%. For heating 10 them, the latter are heated in an oven for 8 to 30 minutes and are to a certain extent post-fried in the oil already adhering to the French fries. In the course of this a certain proportion of the moisture situated in the French fries also evaporates. 15 DESCRIPTION OF THE INVENTION It is an object of the present invention to specify a process for producing a portion-size bag and a 20 portion-size bag containing potato sticks of the type mentioned at the outset, which permits uncomplicated preparation of ready-to-serve French-fried potatoes with simple transportability and storage. This object is achieved by making the bags in such a manner that 25 the potato sticks have a fat content of 5-18% by weight and a water content of 30-60% by weight. The core of the invention is thus to increase shelf life and to reduce the heating time by means of a low water content and a high oil content. Potato sticks which are already 30 to a certain extent completely deep-fried in this way can, firstly, be stored for a relatively long period at temperatures above freezing temperature, and secondly, the effort for preparing them in the home or in the restaurant is minimal, since they no longer need to be 35 heated in the oven for at least 8 to 30 minutes. This is because the low water content and the high fat content in the outer region permit a short rapid heating in which the desired crispiness is rapidly WO 01/21014 - 3 - PCT/CHOO/00489 obtained. Thus a deep-fryer and the associated complex storage of fresh oil can be avoided, and the odor emissions of a deep-fryer do not occur. The deep-fried potato sticks are heated from the bags 'in a 5 conventional oven or an oven especially provided therefor for only a few seconds to two minutes, and served directly. A preferred embodiment of the invention comprises the 10 bag having, after its production, a shelf life which permits the bag to be stored for a period of at least 40-60 days at a typical refrigerator temperature in the range of 2-7 0 C, in particular preferably at 4 0 C, or for a period of at least 4-20 days, in particular 15 preferably 15-20 days, at room temperature, in particular preferably at 15-25*C, without in this case having to accept significant quality losses of the French-fried potatoes obtained after rebaking. This ensures that the portion-size bag containing potato 20 sticks does not need to be transported in freezer vehicles and stored in freezer chests, in a complex manner, but can be transported and stored under simple refrigerator conditions or even at room temperature. It is thus also possible to transport the bags, for 25 example, at room temperature and to store them at refrigerator temperature at the final consumer's premises, without having to accept spoilage of the French fries. This is accompanied firstly by the great advantage that transport and if appropriate also 30 storage become cheaper owing to the higher temperature, and that, in addition, the potato sticks, when they are introduced into the oven from the storage, do not need to be heated from freezer temperature, that is to say -20 to -10 0 C, to the serving temperature. 35 Since a typical refrigerator temperature is 2-7 0 C, up to 30 0 C of heating temperature difference can be saved. Together with the phase transition enthalpy of water WO 01/21014 - 4 - PCT/CHOO/00489 from the solid state to the liquid state, this gives energy savings of up to 50%. However, this not only leads to savings in electricity, but can especially also be used so that the French-fried potatoes aan be 5 brought to serving temperature in a substantially shorter time, that is to say in suitable ovens in a few minutes, or in special ovens, in some circumstances, even within less than 1 minute. If the rebaking takes place, for example, under the action of hot air and/or 10 heat radiation, in particular preferably for a period of 30 to 120 seconds at a temperature of 230 to 290 0 C, in particular preferably from 250 to 280 0 C, after a certain time falling to 180 0 C, very efficient preparation times can be achieved. The decrease leads 15 to the fact that the French fries are first dried at the high temperature and, on reaching a certain dryness, do not burn, but are made mildly crisp at the lower temperature. 20 A further preferred embodiment of the invention comprises the fact that the portion-size bags are gastight and preferably also substantially light-opaque, and the shelf life is at least partially due to a preserving gas atmosphere present in the 25 portion-size bag. In order to obtain the shelf life at temperatures above freezing point, it is advantageous to counteract spoilage of the potato sticks using such a bacterio static gas filling. It is possible to proceed here in such a manner that firstly no oxygen is 30 any longer available in the portion-size bag, which now makes only anaerobic degradation possible, or, alternatively, or in addition, bacterio static gases can be used. Preferably, the preserving gas atmosphere is made low in oxygen and to contain at least one of 35 the gases nitrogen (N 2 ) or carbon dioxide (CO 2 ), but in particular, preferably, is composed of a mixture of nitrogen (N 2 ) and carbon dioxide (CO 2 ) . In addition, the sole use of the two gases in a ratio of 30% nitrogen WO 01/21014 - 5 - PCT/CHOO/00489

(N

2 ) to 70% carbon dioxide (C0 2 ) is advantageous. Thus, the atmosphere is oxyjen-free and the carbon dioxide, at this concentration, has a bacterio static action but does not yet alter taste, which is usually the case at 5 higher CO 2 concentrations. Another preferred embodiment of the invention is that the potato sticks are treated with a preservative during the production process. The portion-size bags 10 are preferably produced in such a manner that raw potato sticks are sliced, which are first blanched in water, in particular preferably then dried on the surface and then deep-fried, the blanching being carried out preferably at a temperature of the 15 blanching water in the range 65-95 0 C, in particular preferably at a water temperature of 85*.C, for a period of 5-10 minutes, in particularly preferably for 7 minutes, and the deep-frying preferably being carried out at an oil temperature of 150-180 0 C, in particular 20 preferably 170 0 C, for a time period of 1 to 9 minutes in a preferably vegetable oil, in particular preferably a palm oil or peanut oil. The treatment with preservative can then be performed by adding a preservative to the blanching water. If the blanching 25 is carried out in a plurality of steps, it can also be sufficient to add a preservative in one of the blanching steps, in particular preferably in the last of the blanching steps. The preservative added can be, for example, sodium sulphite (Na 2

SO

3 ), if appropriate 30 also in the form of sodium hydrogen sulphite or sodium metahydrogen sulphite, preferably in the case of a single-step blanching in such a manner as to achieve a sulphite concentration of 0.05% to 0.3%, in particular, preferably a concentration of 0.1 to 0.2%, or the 35 preservative added can be potassium sorbate, preferably in such a manner as to achieve a potassium sorbate concentration of 0.05% to 0.5%, in particularly preferably a concentration of 0.15%. The maximum values WO 01/21014 - 6 - PCT/CHOO/00489 in this case are determined, inter alia, by country specific food legislation. In this manner, the preservative is effectively added the sticks during blanching, without a separate step being necessary for 5 preservation. In a further embodiment, the potato sticks, after blanching and if appropriate after predrying, are coated with a preservative-containing coating. 10 The coating can be applied, for example, by means of an immersion bath and a starch solution or starch breakdown product solution containing preservatives present therein. 15 Another preferred embodiment comprises dusting the potato sticks after deep-frying or, if appropriate, event only after the subsequent freezing, with a preservative-containing powder, the powder preferably 20 consisting of starch, maltodextrin, or another starch breakdown product or derivative. In particular preferably, maltodextrin is used, with an amount of powder used of preferably 2%% based on the mass of the potato sticks. The preservative used in this form of 25 preparation can be, for example, sodium sulphite (Na 2

SO

3 ), in particular to achieve a sodium sulphite concentration of 0.5%-1.5%, in particular 1.2%, based on the amount of maltodextrin, potassium sorbate, preferably to achieve a potassium 30 sorbate concentration of 3%-5%, in particular 3.75%, based on the amount of maltodextrin, another preservative, or a combination of said substances. In particular, in combination with the abovementioned embodiments, in this manner, the shelf life of the 35 portion-size bags at refrigerator temperature or room temperature can be further increased. In addition, after rebaking, a pleasant crispiness with WO 01/21014 - 7 - PCT/CHOO/00489 simultaneously better tasting inner moisture is established. Further preferred embodiments result from the dependent 5 claims. WAYS FOR CARRYING OUT THE INVENTION High-quality ready-to-serve French-fried potatoes are 10 distinguished by a pleasant outer crispiness with simultaneous well-balanced moisture in the inner of the sticks. This means that the oil content or fat content decreases in an optimum manner from the outside to the inside, and, secondly, the moisture decreases from the 15 inside to the outside. Without this oil and moisture distribution, French-fried potatoes are limp or else too hard and are unpleasant to bite. If French-fried potatoes are packaged in a pre-fried form, in other words, under the term "freshness retention", not only 20 is there the problem of spoilage, but also the problem of maintaining the oil and moisture distribution in the individual potato stick during storage and also after the rebaking. Both problems are usually solved at the same time by packaging the potato sticks and keeping 25 them frozen or at least at refrigerator temperature as described above after deep-frying, bacterial growth being prevented. In addition, the French-fried potatoes are either post-fried or heated and rebaked in an oven for a relatively long time, that it is to say at least 30 half an hour. If the portion-size bags are now to be kept for some time at refrigerator temperature or even room temperature, other means must also be provided which 35 are able to prevent the unwanted effects occurring during storage at such temperatures. The following unwanted processes play an important role during storage: 1) bacterial and fungal growth, 2) changes in WO 01/21014 - 8 - PCT/CHOO/00489 taste, for example owing to the effects of autooxidation, 3) changes in texture owing to equilibration of the concentration gradients of oil and moisture along the stick cross section (migration). All 5 of these processes are preferred during storage above freezing point and must be taken into account during production. Although point 3 does not lead to inedible French-fried potatoes, it leads to limp and soft French-fried potatoes having an unpleasant texture. 10 To enable the production of a portion-size bag containing pre-fried potato sticks which can be stored at room temperature avoiding the abovementioned mechanisms, the following production process is 15 proposed: In a first step, the raw sliced potato sticks (for example from potatoes of the cultivars Ebba, Bintje or Agria) are blanched in a water bath, that is to say are 20 par-cooked at a water temperature below boiling point for some minutes. The potato sticks in this case can be sliced in a special manner, that is to say, for example, in a crinkle cut, in order to achieve a larger surface to volume ratio. The crinkle cut permits a 25 greater oil absorption during the later deep-frying and at the same time faster drying of the edges in the final heating with hot air, which has a beneficial effect on crispiness. In addition, such French fries usually heat more rapidly. Ideally, the blanching takes 30 place at 65-95 0 C, in particular preferably at a water temperature of 85 0 C, and for a time of 5-10 minutes, in particular preferably for 7 minutes. In order to preserve the potato sticks for storage, preservatives are added to the blanching water. Various substances 35 can be used as preservatives. Those which have proved to be suitable are sodium sulphite (Na 2

SO

3 ) or potassium sorbate, or a combination of the two. Sodium sulphite is added in such a manner that a WO 01/21014 - 9 - PCT/CHOO/00489 sulphite concentration of 0.05% to 0.3%, in particular preferably a concentration of 0.2%, is established, and potassium sorbate in such a manner that a potassium sorbate concentration of 0.05% to 0.5%, in 5 particular preferably a concentration of 0.15%, is achieved in the blanching water. The above concentrations apply when the blanching is performed in one step, but it is also conceivable to blanch in several steps and, since the microbial contamination 10 starts from the outside, in particular to operate the last blanching step with preservative. In the case of a last blanching bath, being the only one to contain preservative, the preservative concentration is preferably selected to be somewhat higher. 15 After blanching, the potato sticks are first predried, then deep-fried. Before deep-frying, the sticks, if appropriate, can be dipped in a bath with an aqueous starch solution (or starch derivatives or starch 20 breakdown products such as maltodextrin) provided with preservatives, or a coating can be applied in another manner, which coating may contain preservative. Application of a preservative-containing coating permits a very simple and easily metered addition with 25 preservative, which can make up up to 10-18% of the French fry. The amount of coating can be set fairly simply via the viscosity of the solution. The viscosity of the solution may be set via the starch concentration, and with increasing viscosity more 30 coating will remain on the stick in an immersion bath. Under certain circumstances, this method can prove to be preferred, because it is found that the efficacy of the treatment of the sticks with preservative during blanching can in some circumstances depend to a not 35 insignificant extent of the cell structure of the potato sticks, which may lead to undesirably different treatment efficiencies.

WO 01/21014 - 10 - PCT/CHOO/00489 Since the deep-frying represents the only deep-frying of the sticks, to impart good taste this should also be performed in a high-quality grade deep-frying oil. Deep-frying is performed at an oil temperature of 150 5 180 0 C, preferably 170 0 C, for a time period of 1 to 9 minutes in as far as possible a vegetable oil, for example a palm oil or peanut oil. The deep-frying should proceed for a relatively long time, in order that the French-fried potatoes produced in this manner 10 have a water content in the range 30-60%, in particular preferably approximately approximately 45% to 50%, an oil content of approximately 12-15% and a fat-free dry matter content of approximately 35-40%. If appropriate, deep-frying can also proceed in several stages, in 15 particular double deep-frying can be advantageous. Since palm oil has a melting point above room temperature (Ts 2 +approximately 45 0 C) and this oil is thus in the solid state at the storage temperatures, 20 its use can have advantages, compared with peanut oil, in particular with respect to water transport (migration) and shelf life. This is because in order to prevent the French fries from becoming limp, the oil should act as a water barrier at the surface. Also, the 25 low water content in the process described here, the coating, the rapid heating of the French fry in the oven and the crinkle cut of the sticks are effective means for preventing the French-fried potatoes from becoming limp. After deep-frying the sticks are sterile 30 and the actual microbial contamination takes place later and as a result essentially from the outside during further processing, that is to say on conveyor belts and in packaging machinery etc. Further processing should therefore take place in as clean a 35 manner as possible. After deep-frying, the French-fried potatoes are best frozen in large amounts (as bulk) and prepackaged WO 01/21014 - 11 - PCT/CHOO/00489 temporarily and then, usually in the frozen state, packaged in small bags. The typical high output of an industrial deep-fryer generally permits no direct sufficiently rapid packaging into the small portion 5 size bags which contain approximately 115 g to 250 g. After deep-frying and chilling, or after freezing, before portioning, the potato sticks are preferably further dusted with a powder, for example starch, 10 starch derivative, maltodextrin or another starch breakdown product. The powder should be such that after possible absorption of moisture from the potato stick, it does not contribute to the sticks sticking together. Those which have proved suitable are starch derivatives 15 or starch breakdown products, for example maltodextrins. These should not have excessively long chains (sticking together) and should also not be too short (sweet taste) and should make possible attractive browning after rebaking (for example preferably 20 maltodextrins having a dextrose equivalent of approximately 17-19). The amount of powder used is preferably 2%%, based on the mass of the potato sticks. The dusting can be used and optimized firstly for increasing the final crispiness, and secondly it 25 permits the application of preservatives to the sticks, by adding preservative to the powder. Thus the preservative added to the powder can be sodium sulphite (Na 2

SO

3 ), potassium sorbate, sorbic acid, or other preservatives or combinations 30 thereof. Sodium sulphite in this case advantageously to achieve a sulphite concentration of 0.5%-1.5%, in particular 1.2%, based on the amount of powder; potassium sorbate preferably to achieve a potassium sorbate concentration of 3%-5%, in particular 3.75%, 35 based on the amount of maltodextrin. After deep-frying, the pre-fried potato sticks are, as indicated above, frozen and packaged in the portion- WO 01/21014 - 12 - PCT/CHOO/00489 size bags. The French fries are best stored as long as possible in the frozen state and then not packed and thawed until required. 5 The portion-size bags consist optimally of a light-opaque and gastight material and may be sealed gastightly. The gastightness is particularly important, since otherwise the protecting atmosphere slowly degrades and the shelf life due to the protecting 10 atmosphere decreases. A suitable material is, for example, a laminate of a plastic layer and a thin aluminum layer. To preserve the bag contents, the bag is filled under essentially sterile, or at least aseptic as far as possible, conditions, and in addition 15 the stick-filled portion-size bag is flushed with a gas displaying a preservative action and then sealed. The initial microbial count during packaging is critical for the shelf life and should be as low as possible, in particular preferably less than 100 microbes/g. 20 Suitable preserving gas atmospheres are, for example, low-oxygen gas mixtures. Thus the use of pure nitrogen gas does not permit growth of aerobic microbes. Secondly, pure carbon dioxide is bacterio static, both for aerobic and for anaerobic microbes, but 25 unfortunately at high concentrations has properties which alter taste. A good compromise which allows good preservation without changes in taste is achieved by using just these two gases in a ratio of 30% nitrogen

(N

2 ) to 70% carbon dioxide (CO 2 ). 30 The abovementioned means for preservation, that is to say the preservatives in the blanching water, in the coating and/or in the dusting and the use of a protecting gas atmosphere in a gastight and 35 light-opaque bag are preferably used individually or in combination to achieve a shelf life as long as possible.

WO 01/21014 - 13 - PCT/CHOO/00489 The French fries are only further heated in an oven on the part of the final consumer. The French-fried potatoes are to be crispy and golden-brown and warm to the interior, without drying in the interior-. The 5 extent and type of heating which proceeds here has an effect on the resulting crispiness and should therefore be performed in a controlled manner. The size, in particular the cross section of the potato sticks, the intensity of the preceding deep-frying and the type of 10 heating play a critical role here. Heating can be performed by means of hot air and/or heat radiation and/or action of microwaves. Heating under a hot air stream at an air speed of 1-10 m/min and a temperature of initially 230-290 0 C, in particular, preferably at 15 250 0 C, then decreasing to approximately 180 0 C, all during a period of 30-120 seconds, if appropriate supported by heating lamps, leads to the establishment of a moisture distribution which is ideal for the use desired here within the potato stick and an optimum 20 crispiness. In particular decreasing the temperature in the second phase of baking leads to smooth rebaking and targeted crispiness. This is achieved with typical potato sticks having a cross sectional area of 7 x 7 mm, if appropriate using crinkled fries having a 25 full crinkle distance of 1.5 to 2 mm.

Claims (2)

1. A portion-size bag having a portion packaged therein of prefried potato sticks from which, by later 5 rebaking without repeated deep-frying, ready-to-eat French-fried potatoes can be obtained, in which the potato sticks have a fat content of 5-18% by weight and a water content of 30-60% by weight. 10 2. The portion-size bag as claimed in claim 1, wherein the bag, after its production, has a shelf life which permits the bag to be stored for a period of at least 40-60 days at a typical refrigerator temperature in the range of 2-7 0 C, in particular preferably at 4 0 C, 15 or for a period of at least 4-20 days, in particular preferably

15-20 days, at room temperature, in particular preferably at 15-25 0 C, without in this case having to accept any significant quality losses of the French-fried potatoes obtained after rebaking. 20 3. The portion-size bag as claimed in one of claims 1 and 2, wherein the portion-size bags are gastight and preferably also light-opaque, and the shelf life is at least partially due to a preserving gas atmosphere 25 present in the portion-size bag. 4. The portion-size bag as claimed in claim 3, wherein the preserving gas atmosphere comprises at least one of the gases nitrogen (N 2 ) or carbon dioxide 30 (C0 2 ), but preferably is compared of a mixture of nitrogen (N 2 ) and carbon dioxide (CO 2 ), in particular preferably in a ratio of 30% nitrogen (N 2 ) to 70% carbon dioxide (CO 2 ) 35 5. The portion-size bag as claimed in one of the preceding claims, wherein the potato sticks are treated with a preservative during the production process. WO 01/21014 - 15 - PCT/CHOO/00489 6. The portion-size bag as claimed in one of the preceding claims, wherein the prefried potato sticks are produced from raw potato sticks which are first blanched in water, in particular preferably then dried 5 on the surface, and then deep-fried, the blanching being carried out if appropriate in a plurality of steps and preferably at a temperature of the blanching water in the range 65-95 0 C, in particular preferably at a water temperature of 85 0 C, for a period of 10 5-10 minutes, in particular preferably for 7 minutes, and the deep-frying preferably being carried out in one or more steps at an oil temperature of 150-180 0 C, in particular preferably 170 0 C, for a time period of 1 to 9 minutes in a preferably vegetable oil, in particular 15 preferably a palm oil or peanut oil. 7. The portion-size bag as claimed in claim 6, wherein a preservative is added to the blanching water in at least one of the blanching processes. 20 8. The portion-size bag as claimed in claim 7, wherein the preservative added is sodium sulphite (Na 2 SO 3 ), preferably in such a manner as to achieve a sodium sulphite concentration of 0.05% to 0.3%, in 25 particular preferably a concentration of 0.2%. 9. The portion-size bag as claimed in one of claims 7 and 8, wherein the preservative added is potassium sorbate, preferably in such a manner as to 30 achieve a potassium sorbate concentration of 0.05% to 0.5%, in particular preferably a concentration of 0.15%. 10. The portion-size bag as claimed in one of claims 6 35 to 9, wherein the potato sticks, after deep-frying, or if appropriate, even only after the subsequent freezing, are dusted with a preservative-containing powder, the powder preferably consisting of starch, a WO 01/21014 - 16 - PCT/CHOO/00489 starch derivative, maltodextrin or another starch breakdown product, and, in particular preferably, the amount of the powder used is preferably 2%, based on the mass of the potato sticks. 5 11. The portion-size bag as claimed in claim 10, wherein the preservative added to the powder is sodium sulphite (Na 2 SO 3 ), in particular to achieve a sodium sulphite concentration of 0.5%-1.5%, in 10 particular 1.2%, based on the amount of powder, potassium sorbate, preferably to achieve a potassium sorbate concentration of 3%-5%, in particular 3.75%, based on the amount of powder, or another preservative, or comprises a combination of said 15 substances. 12. The portion-size bag as claimed in one of the preceding claims, wherein the rebaking is performed under the influence of hot air, and using an air stream 20 of 1-10 m/sec, in particular preferably 4 m/sec, and/or heat radiation, in particular preferably for a period of 30 to 120 seconds at a temperature of 230 to 290 0 C, if appropriate decreasing towards the end of the baking time to 180 0 C. 25 13. The portion-size bag as claimed in one of the preceding claims, wherein the material used for the portion-size bag is a laminate which, in addition to a plastic layer, comprises an aluminum layer. 30 14. The portion-size bag as claimed in one of the preceding claims, wherein the potato sticks have a crinkle cut. 35 15. A process for producing a portion-size bag containing a portion packaged therein of prefried potato sticks from which, by later rebaking without repeated deep-frying, ready-to-eat French-fried WO 01/21014 - 17 - PCT/CHOO/00489 potatoes can be obtained, which comprises preparing the potato sticks to a fat content of 5-18% by weight and a water contents of 30-50% by weight, as a result of which the bag, after its production, has a shelf life 5 which permits the bag to be stored for a period of at least 40-60 days at a typical refrigerator temperature in the range of 2-7 0 C, in particular preferably at 4 0 C, or for a period of at least 4-20 days, in particular preferably 15-20 days, at room temperature, in 10 particular preferably at 15-25 0 C, without in this case having to accept significant quality losses of the French-fried potatoes obtained after rebaking,. in particular preferably also comprising the features of claims 2-14.