SE464611B - SEAT AND APPLIANCE FOR FOOTBALL COOKING OF FOOD - Google Patents

Description

464 611 10 15 20 25 30 35 2 by means of standardized color charts, the oil content, the water content, the number of folds, lumps, blisters and the like. The ability of a particular type of potato to produce desired chip qualities is defined as the "chipping" quality of the potato. Conventional chips usually have a fat content in the range of about 32-40% by weight and can be cooked either batchwise or continuously. The normal cooking conditions for conventional potato chips in a continuous process include external heaters and continuous oil circulation. The chip is initially immersed in hot oil at a temperature of about 182-199 ° C and transported through the digester so that there is a temperature drop in the oil along the cooking path. The cooked chips are taken out of the oil with a temperature of about 160-177oC. There is usually a 170-250 temperature drop during the continuous cooking of conventional potato chips. In some cases, multi-zone boilers are used, where the temperature drops along the cooking path in one zone, then increases when entry into the next zone takes place, which leads to a sawtooth temperature profile along the cooking path.

Other continuous cooking systems for conventional potato chips include direct-fired cookers and cookers with submerged tubes. The time-temperature profile of the digester can be changed by modifying the design of the digester, but there are several serious limitations in that the heat transfer capacity is limited by the heat transfer surface within the digester. These types of cookers are usually necessarily larger than cookers with external heat exchangers, the comparison being based on the same production rates, and they contain significantly more cooking oil than is required for cooking the food product. The oil's turnover rate, ie the time taken before the entire volume of cooking oil in the system is absorbed into the chips and must be replaced with new oil, is extremely important for maintaining low free fatty acid cooking oil. 10 15 20 25 30 35 464 611 3 Another factor that affects the quality of the cooking oil is the film temperature to which the oil is exposed on the heat transfer surfaces. The internally heated boilers cannot reach both low oil volume and low oil film temperatures, in contrast to externally heated systems.

Especially when it comes to potato chip preparation, there are types of potato chips that differ from the conventional chips in terms of color, texture, oil content, number of folds, salt content and lack of defects. These types of chips are recognized and preferred by some consumers. The preference for certain chip variations can be attributed to ethnic or regional habits, fashion or the consumer's desire to reduce fat intake.

One of these variations on chips is the low-fat potato chips, which have been processed in a continuous cooking system, where the oil temperature remains relatively constant or increases throughout the cooking period, ie within a temperature range of about 135-177 ° C. The low-fat chips are cooked for about 2-3 minutes, depending on the type of potato used, the slice thickness and the boiling temperature. The fat content of low-fat chips and potatoes can be in the range of about 22-24% by weight or less, compared with the conventional chips 32-40%.

A problem with conventional float cooking is that when the potato slices come into contact with the fat, its temperature is about 185 ° C, which decreases during the residence of the slices in the cooker. Due to the high temperature of the fat, an explosive boiling takes place in the first part of the boiler, the result of which is that the steam pressure in the discs causes certain cell walls to rupture. These ruptured cells will be at least partially filled with fat when the water in the disks has disappeared almost completely. For this reason, conventional potato chips contain a high proportion of fat.

When cooking low-fat chips, on the other hand, the low coke oil temperature and especially the time and temperature curve allow the water to leave the potato cell 464 611 10 15 20 25 30 35 4 at a lower rate than with conventional chips, thereby minimizing cell breakage while a sufficient vapor pressure is maintained to minimize the entry of oil into the cells.

There are at least two types of potato chips that the consumer considers to be neither low-fat chips nor conventional potato chips. One of these types is usually characterized by the descriptive terms "homemade" or "saucepan" chips. Instead of cooking in a continuous process, which is commonly used for conventional chips, "homemade" chips are cooked in a batch process and this chip is usually crispier and heavier than conventional chips. While conventional chips are normally cooked in oil, "homemade" chips are sometimes cooked in a raft, which is solid at room temperature. Since "homemade" chips are processed batchwise, it is not only very laborious to produce but also product uniformity is difficult to control, and the energy utilization of the process is lower than can be achieved with a continuous process.

In some regional markets, a certain non-uniformity and variation in the finished food product in terms of color, fat and moisture content can be tolerated by the consumer, but in larger than national markets such a variation is more difficult to accept.

Another special type of chip that has achieved success with the consumer is so-called "Maui" chips. This can be recognized by the fact that it normally has a heavier thickness than conventional chips, has greater color variation and is characterized by a harder bite. "Maui" chips are treated differently from conventional chips in that the uncooked potato slices are usually unwashed or only lightly washed before being immersed in the oil. In the case of conventional chips, the uncooked slices were usually washed before being immersed in oil to remove the surface starch. Furthermore, "Maui" chips are usually made in batches, although continuous processes exist. The time-temperature profile of a batch cooking process for "Maui" chips is different from that of conventional chips or low-fat chips in that the oil temperature decreases during the initial part of the cooking period, then increases during the latter. part of the cooking period. Its cooking time is longer than that of normal chips, usually in the range of 7.5-9 min. Although we do not want to dwell on a particular theory, our belief is that the characteristic time-temperature profile, the type of potato used and the surface starch on the slices are factors that must at least be considered for the production of "Maui" chips. To make "Maui" chips, the unwashed or lightly washed uncooked slices are typically first immersed in hot oil at a temperature of about 143 DEG-166 DEGC. During about 2-4 minutes, the oil temperature drops by about 17 ° C, depending on the size of the boiler, the oil volume, the batch size and the surface water. After this period, boiling continues, with the temperature rising gradually, usually by about 11-17 ° C. Partly due to the fact that "Maui chips" require a longer cooking time and also due to their unusual time-temperature profile, the chips are usually produced by a batch process, since conventional continuous cookers have linear, sawtoothed or gradually decreasing time-temperature profiles for cooking. , which profiles are unsuitable for the production of "Maui" chips.

It is therefore desirable to provide an apparatus suitable for continuous cooking of various types of chips, including chips which have hitherto been mainly cooked by a batch process.

It is also desirable to provide a method and apparatus for improving the quality of conventional potato chips so that lower chipping quality potatoes can be used to make commercially acceptable chips, for example, dark or discolored chips are the result of the presence of reducing sugar 464 611 10 15 15 25 25 30 35 6 which has been formed from starch due to incorrect storage conditions, growth conditions and variations in the potatoes, It is thus advantageous to provide an apparatus with which the cooking conditions are easily varied in the cooker for adaptation to the peculiarities (such as the sugar content) of the potatoes currently being processed, all to achieve the constant and light chip color.

It is also desirable to be able to vary the oil content of the potato chips. For example, low-fat potato chips require a special process, but the oil content can also be varied using the oil temperature, which is partly determined by the time-temperature relationship. It is thus desirable to be able to easily vary the temperature profile of the cooking oil in a cooking appliance, since the cooking time can be easily varied.

It is therefore highly desirable to provide an apparatus which can be set or programmed to cook all types of potato chips and which can handle variations in the raw potatoes.

An object of the invention is to provide such an apparatus for continuous processing of cooked food products which is adaptable to very varying time-temperature profiles.

Another object of the invention is to provide an apparatus which can create an adjustable time-temperature cooking profile so as to deal with variations in the solids content, sugar / starch content and other characteristics of the raw potatoes, too much to achieve a uniform and / or improved product.

These and other objects are disclosed in the following description of a preferred embodiment.

The present invention provides an apparatus for the continuous processing of food products, which apparatus comprises a container for hot oil, a transport means for supervised feeding of food products along a predetermined path in the container, heat exchange means. outside the container and arranged to exchange heat with oil communicating with the container, means for removing oil with a high moisture content from the container, distribution means for recirculating oil taken from the container through a plurality of inlet means, which are arranged along the path, which inlet means comprise means for mixing the high moisture recycled oil with oil communicating with the heat exchange means, and means, such as a valve, for proportioning the relative amounts of the high moisture recycled oil and the oil communicating with the heat exchange means to the mixing means.

One of the advantages of the present invention is that it effectively handles the problem of oil having a high moisture content. Boiling oils at 135 ° C and hotter may contain water in drop form. The water enters the oil from both the surface of the food product and expelled from the food product. The mechanism behind water in oil at a temperature above its boiling point is the result of several phenomena. A water drop with a spherical shape has a small surface area compared to its volume. When heat is transferred from the hot oil to the colder water, the surface of the water droplet changes state from liquid to steam. This requires a large amount of heat, more specifically 2260 J / g water at atmospheric pressure. When this state change occurs, the surface of the water droplet is surrounded by steam, which is a poor heat conductor compared to water. This steam casing further reduces the heat transfer from the oil to the water drop. If, on the other hand, the oil is stirred sufficiently so that the water casing is removed from the water droplet, or more importantly if the water droplet is divided into small particles, the heat transfer rate increases sharply and a rapid state change from water to steam takes place.

It is essential that most of the water is removed from the oil before it leaves the digester and meets the suction from an oil circulation pump, since the reduced pressure and turbulence occurring in the suction side of the pump accelerates the steam removal from the oil and cavitation occurs. in the pump, which leads to pump damage and, as most pumps operate on a volumetric basis, to a reduction in the mass flow of the oil as a large part of the volume being pumped is replaced by steam.

This situation has serious consequences for the heat exchange system due to reduced oil flow rates and locally hot spots on the heat transfer surface due to the presence of steam instead of oil. The cavitation can sometimes become so severe that the oil circulation stops completely.

Since a minimum volume of oil in the system is of great importance for maintaining a low content of free fatty acids in the oil, systems that remove water from oil but require large volumes of cooking oil are not practical.

In the accompanying drawings, Fig. 1 is a schematic illustration of a preferred cooking apparatus according to the invention, Fig. 1A is a detailed view of a mixing device 31A and 32B in Fig. 1, Fig. 2 is a schematic representation of a second preferred apparatus according to the invention, Fig. 2A is a detailed view of a mixer 56A and 56B in Fig. 2 and Fig. 3 is a plot of a typical time-temperature curve and time-required energy curve for cooking "Maui" potato chips.

The cooker according to the invention can be used as the continuous boiling component in a food processing system. The cooking apparatus according to the invention can thus be used together with a disc or combination of discs and washers, located upstream of the cooker. The slicer can be placed upstream of the digester, with sliced raw food products being transported by suitable means and deposited at the inlet end of the digester. Alternatively, the slicer can be arranged above the inlet end of the cooker, the slices of raw food falling directly into the hot oil. It is preferred that the slicer be adapted to a washing device, which may optionally be used, so that there is an option to cook washed raw potato slices for conventional potato chips, or unwashed raw potato slices for "Maui" chips. The washing device is commercially available, so that a washing step can be used or omitted without the need to change the equipment.

Downstream of the cooker, a degreasing device such as that described in SE 833 714 or US 3,627,535 can be used, wherein the cooking system can produce low-fat potato chips. Also downstream of the boiler there may be a conventional seasoning and packaging device.

Reference is made to Fig. 1, which schematically shows a preferred cooking apparatus according to the invention.

A container 10 is arranged to hold hot cooking oil.

The raw food product is introduced into the container in the area indicated by the arrow ll. While the food products are boiling, they will usually float and eventually come into contact with a conveyor 12 which, together with the oil velocity in zone A, controls the residence time. The conveyor 12 also transfers the chips to a zone B, where a plurality of rotating paddles 13 strike, separate, stir and control the feed of the chips.

The forward speed of the cooking oil is usually higher than the paddle speed, so that the paddles 13 hold the chips back and ensure an even cooking time. After the chips have passed through the stirring zone B, they contact a conveyor 14, which transfers them to an end zone C, where they are passed through the hot oil by means of a winged, immersed conveyor belt 15, which keeps the chips below the oil surface while controlling the feed. through the cooker. The cooked chips 464 611 10 15 20 25 30 35 10 are then removed from the digester by means of a removal conveyor 15A and the excess surface oil is simultaneously drained from the product. It can be seen that the total cooking time is determined by the time it takes for a certain disc to run through the length of the container 10, and the temperature profile inside the container is determined by the temperature gradient, if any, along the cooking path in the container. 10.

Inside the transfer conveyors 12 and 14 are overflows 12A and 14A, respectively, which determine the oil level in zone A and B, respectively. Since the amount of oil entering a zone must be equal to the amount of oil leaving the same zone, this overflow maintains the oil level while allowing excess oil to flow from the zone. A to zone B, and from zone B to zone C. This feature provides much greater flexibility in setting oil circulation rates in each zone in order to achieve the desired temperature profile.

During the cooking of potato chips, the first zone inside the cooking appliance produces a high level of water in the oil as a result of water being removed from the surface of the raw product during the cooking process. The reaction of water with the oil (hydrolysis) shortens the useful life of the oil, so that water should be removed from the oil as soon as possible.

The apparatus of Fig. 1 is equipped with means for varying the local cooking oil temperature at different points along the cooking path, so that the time-temperature profile along the cooking path can be made to substantially correspond to a predetermined time-temperature curve, and in particular with a time temperature curve that has at least one slope change. Slope change in a curve means that there is at least one point in the time-temperature profile where the temperature changes from falling to increasing or from increasing to falling. Reference is made again to Fig. 1. The container 10 is provided with oil outlet lines 17A, 17B and 17C.

The oil discharged through line 17A during the boiling process contains a significant amount of water, while the amount of water in the water discharged through line 17B is slightly smaller. The oil discharged through line 17C usually contains a relatively small, if any, amount of water, since the cooked chips at the end of the cooking process contain a small amount of water. The oil in line 17C is pumped by means of a pump 18 to a heat exchanger 19, where the oil is reheated for recirculation to the container 10. The heat exchanger 19 may be a fuel-fired burner or some other heat transfer device of conventional type. The reheated oil leaving the heat exchanger 19 through line 20 is then distributed through a network of lines 21, 22, 23 and 24 to the container 10. However, before entering the container 10, the recycled hot oil in lines 22 and 23 is mixed with oil from line. 17B and 17A, respectively, which have a high water content. The proportion of the oil mixtures from lines 22 and 17B is controlled by means of valves 25 and 26 and the proportion of oil from lines 23 and 17A is regulated by means of valves 27 and 28. Furthermore, suitable pumps 29 and optionally a filter 30 are provided. The device for mixing the oil with high water content and the hot oil includes components 31A, 31B, 32A and 32B.

The aforementioned components 31A, 31B, 32A and 32B are shown in detail in Fig. 1A. The oil with a high water content is pressed through a distributor and through a plurality of nozzles 32A. The hot oil from the heat exchanger 19 is also pressed through a distributor and through a plurality of nozzles 32B which are larger in diameter and concentric with the nozzle 32A. The rapid contact and intimate mixing of the oil with a high moisture content with the net oil causes the dispersed water droplets to evaporate rapidly from the oil, whereby the moisture content of the oil is lowered when the oil re-enters the tank 10. As shown, the nozzles 32A and 32B can be arranged at an angle to the oil flow in the tank 10. Alternatively, the high water content oil can be forced through the nozzles 32B and the hot heat exchanger oil can be forced through the nozzles 32A, i.e. so that the function of the nozzles is changed.

The relative flow rates of hot oil through the nozzles 32B and colder oil through the nozzles 32A determine the average temperature of oil in the vicinity of each inlet 32B of the container 10. By arranging a plurality of inlets 32B along the boiling path in the container 10, the time-temperature profile along the boiling path can be adjusted. that it substantially corresponds to each predetermined curve. Various temperature monitoring means, such as thermocouples, can be provided at suitable points, in order to monitor the temperature characteristics of the oil. Exemplary temperature monitoring units 33 are shown in Fig. 1.

Fig. 2 shows another preferred apparatus according to the invention. The difference is that according to Fig. 2 two oil streams flow in opposite directions, both of which are discharged to a sump 40 and 50 in the tank having sections 41A and 41B. The sliced raw food products leave the conveyor belt 42 and fall into the hot oil in the tank 41A. The chips are transported through the boiling zone A by the combination of the forward speed of the oil and the speed of the immersed conveyor 43. This also serves to separate the chips from the oil exiting through the oil outlets 46 and the sump 40 and 50. This forced separation of the chips from the oil exiting the float boiler provides greater flexibility in adjusting the oil flows through intermediate inlets and outlets 56A, 56B and 46, which forcibly provide the desired time-temperature curve. When the chips leave zone A, they are gripped by the front portion of the conveyor 44, which forcibly guides the chips through both zones B and C by means of a plurality of suspended positioning wings 44A. Since the chips in zone B can still contain sufficient moisture which, enclosed in a limited area, can give rise to clumping of chips which are boiled, the belt portion of the conveyor 44 is kept above the oil level and only the positioning wings are used to regulate the chip movement. Where the chips reach the zone C, the conveyor belt 44 is lowered to reduce the product space and then the conveyor belt lowers the chips below the oil surface, where the cooking is completed.

The positioning vanes 44A also serve as wipers to prevent the accumulation of starch or product particles on the tank bottom. The application of the wings 44A is similar to that shown in US 3,472,155.

Wings can also be attached to the strap 43 to provide a similar wiping effect in zone A.

The cooked chips are transported to the outlet conveyor 45 and taken out of the digester. The oil in the tank 41b flows down into the sump 50 to the left while the oil in the tank 41A flows down into the sump 40 to the right, as shown in Fig. 2. The high water content in the zone A is substantially enclosed in the tank 41A and is discharged through a network of pipes 46 and pumped by means of the pump 47 for recirculation to the tanks 41A and 41b through lines 48 and 49. The substantially moisture-free oil from zones B and C which is drained to the sump 50 from the tank 41b is by a partition 50 separated from the oil which is drained to the sump from the tank 4lA.

This substantially moisture-free oil is led by means of a line 51 and pump 52 to a heat exchanger 53, where the oil is reheated to a suitable temperature. The reheated oil is then recycled to the tank 41A through a network of lines 54 and to the tank 41b through the line 55. The hot oil in the lines 54 is mixed with the high water content coming from the lines 48 and the hot oil from the line 464 611 Mixed with the high water content oil from line 49 by means of the mixing devices 56A and 56B, which are shown in detail in Fig. 2A.

Reference is made to Fig. 2A. The hot oil from the heat exchanger is passed through a distributor and through nozzles 57B. The colder oil with a high water content is passed through the distributor and through nozzles 57A, which are concentric with the nozzles 57B. The rapid contact between the hot oil and the colder, water-rich oil causes intimate mixing and rapid expansion of the water droplets and their rapid evaporation.

As shown, the inlet nozzle 57B is perpendicular to the oil flow inside the tanks 41A and 41B.

The localized temperature along the sections of the tank 41B can be controlled by arranging along the boiling path inside the tank 41b of the inlet nozzles 58 which contain reheated oil from the heat exchanger 53 and which rapidly evaporate the moisture in the oil before it reaches the sump 40 and the pump 52. , which is not shown, can be conveniently placed along different conduits and in suitable places in the tank for controlling the room temperature inside each tank 41A and 41l. The relative flow of hot and cold oil through the various lines can be regulated by means of different valves 60.

Both apparatus embodiments according to Figs. 1 and 2 can be used in a continuous cooking process, where the cooking path through the oil is characterized by a time-temperature profile which can be adjusted to substantially correspond to a predetermined time-temperature curve.

In addition, the apparatus of Figures 1 and 2 removes the dispersed water droplets from the oil without adding additional volume of oil to the system.

The apparatus according to Figs. 1 and 2 are particularly suitable for carrying out a continuous process for cooking a food product which requires a time-temperature profile, where a temperature drop is followed by a rise in temperature. Fig. 3 shows a plot of a typical time-temperature profile and a profile over time and amount of energy required for cooking "Maui" potato chips. Although these curves were determined for a batch cooker, they can be substantially reproduced using a continuous cooker according to Fig. 1 or 2. As shown in Fig. 3, the time-temperature profile for cooking "Maui" chips shows an initial cooking temperature of about 16 ° C, which temperature is gradually lowered for about 3-3.5 minutes to about 150 ° C. After 3-3.5 minutes, the temperature rises and gradually increases over the next 4.5 minutes to a final temperature of about 106 DEG C., before the next batch begins to boil.

It should be apparent from the foregoing that various modifications may be made within the scope of the invention. In particular, in a particularly preferred embodiment, a degreasing unit can be arranged downstream of the digester in Fig. 1 or 2 for the production of a food product with a substantially reduced fat content.

Claims (5)

1. 464 g611 10 15 20 25 30 16 CLAIMS 1. Apparatus for cooking food products, comprising: a container (10: 41A, 41b) for hot oil, a transport means (12-15; 43, 44) for transporting food products along a predetermined path inside the container, a heat exchanger (19; 53) arranged outside the container for heat exchange with oil communicating with the container, means (17A, 17B, 17C; 40) for removing high moisture oil from the container, distributor (21-24 54, the oil withdrawn from the container through a plurality of 55) for recirculation of inlet means, arranged along the path, which inlet means comprise means (31A, 31B, 32A, 32B; 56A, 56B, 57A, 57B) for mixing the high water content oil. with the oil communicating with the heat exchanger, characterized in that the apparatus comprises means (27, 28; 60) for proportioning the relative amounts of the high water content oil and the oil communicating with the heat exchanger to the mixing agent, and that the mixing agent contains grasp two concentric nozzles (32A, 32B; 57A, 57B), which receive the current of the oil with a high moisture content or the oil which communicates with the heat exchanger. Apparatus according to claim 1, characterized in that the oil flow in the container is parallel to the longitudinal direction of the web. 3. Apparatus according to claim 1, characterized in that the container absorbs two separate streams of oil, the flow directions of which are opposite _ and which are both parallel to the longitudinal direction of the web. 4. A method of continuously cooking food products, according to which uncooked food products are continuously introduced into one end of a cooking zone containing hot oil, the food product is continuously transported along a path through the cooking zone, and the cooked food product is continuously is extracted from the oil after it has passed through the web, characterized in that the web boiling zone has a time-temperature profile which substantially corresponds to a predetermined curve having at least one sign change on its slope, which is achieved by amounts of oil withdrawn from the end of the web and upstream of the oil withdrawn from the web after proportioning are mixed with each other in the form of concentric jets, which are reintroduced into the web. 5. The method of claim 4, characterized in that the food product consists of potato chips.