JPH0374093B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the field of food processing, and more particularly to a method for browning snack foods.

The methods used for browning foods, particularly snack foods such as potato chips, banana chips, and the like, on an industrial scale include batch processing and continuous processing. For example, in batch processing for cooking potato chips, a batch of washed or unwashed potato slices is cooked in a cooker containing a cooking medium such as hot oil, and then the entire batch is cooked in a cooking medium containing a cooking medium such as hot oil. It is then taken out and further processed such as draining oil and seasoning. The cooking medium is
It may be oil, lard or other conventional materials. For convenience,
Although the cooking medium will be referred to as oil below, it will be understood that any conventional cooking ingredient may be utilized.

Continuous processing of potato chips typically involves e.g.
It involves conveying the uncooked potato slices through a cooking device containing hot oil, the oil being heated such that the length of time the potato slices are in the oil and the temperature of the oil are appropriate to produce the desired potato chips. It is the kind of oil that is. There are various arrangements of cooking equipment, the most common of which employs a linear conveyor. In such cooking devices, the slices are continuously placed in oil at one end of the cooking device and advanced under control through the cooking device where the potato chips are removed from the other end. In either batch or continuous processing, the oil can be heated by a heater immersed directly into the oil or by circulating the oil to an external heater and returning the heated oil to the cooking equipment. .

Traditional potato chips are characterized based on standardized color charts, oil content, moisture content, number of pleats, number of clumps, number of bubbles, etc. The ability of a particular type of potato to achieve a desired chipping quality is defined as its chipping quality. Conventional chips typically have a fat content in the range of about 32-40% by weight and can be prepared by either batch or continuous processing. Typical cooking conditions for conventional potato chips in continuous processing utilize external heating devices and continuous oil circulation. The chip initially rotates about 360°
It is immersed in hot oil at a temperature of ~390°C (182-199°C) and is conveyed through the cooking equipment, where there is a decrease in the temperature of the oil along the cooking path. The cooked chips are removed from the oil at a temperature of about 320-350°C (160-177°C). During the process of continuous cooking of conventional potato chips, there is usually a temperature drop of 30-45°.
In some cases, multi-area cooking equipment is used;
The temperature decreases along the cooking path within one region and then increases as it enters the next region, resulting in a "sawtooth" shaped temperature curve along the cooking path.

Other continuous cooking systems for conventional potato chips include open flame immersion cooking devices. The time-temperature curve through the cooking appliance can be changed by also modifying the cooking appliance design;
There are severe limitations imposed by the fact that heat transfer capacity is limited by the transfer surfaces available within the cooking appliance. These types of cooking equipment are usually necessarily larger than external heat exchanger cooking equipment for the same production rate and, more importantly, have a much larger cooking capacity than is required to cook the food. Contains oil unnecessarily. The oil turnover rate refers to the time during which the entire volume of cooking oil contained within the system is absorbed into the chips and replaced with fresh oil, but this turnover rate maintains the free fatty acids of the cooking oil low. It is extremely important. Another fact that affects the quality of cooking oil is the film temperature that the oil experiences on the transmission surface. Internally heated cooking appliances are unable to achieve both small oil volumes and low oil film temperatures compared to externally heated systems.

However, particularly in the area of potato chip processing, there are types of potato chips that differ from what may be considered conventional chips in terms of color, texture, oil content, number of pleats, salt content, and defect-free nature. These types of chips are recognized and preferred by some consumers. These preferences for some variation in chips may be related to ethnic or regional customs, fads, or a consumer's desire to reduce fat intake.

One of these variants of chips is low-fat potato chips, which are processed by a continuous cooking system whereby the temperature of the oil is maintained relatively constant or during the entire cooking period. ie, typically in the temperature range of about 275-350°C (135-177°C). Low-fat potato chips are about 2-3
However, the cooking time is
It depends on the type of potato used, the thickness of the slices, and the cooking temperature. The fat content of low-fat potato chips is low, in the range of about 22-24% by weight, compared to the usual 32-40% of conventional chips.

The problem with traditional deep-frying cooking is that
When the potato slices come into contact with the fat, the temperature of the fat is approximately 365°C (185°C), and this temperature decreases while the slices remain in the cooking device. Due to the high temperature of the fat, explosive boiling occurs in the first part of the cooking device, as a result of which the vapor pressure within the slices ruptures some of the cell walls. The ruptured cells become at least partially filled with fat when almost all the water contained within the slices has evaporated away. For this reason, conventional potato chips contain a large proportion of fat.

However, when cooking low-fat chips,
The low cooking oil temperature and especially the time-temperature curve allow water to be removed from the potato cells at a slower rate than in conventional chips, thus minimizing cell rupture, while the oil Maintain enough steam to minimize entry into the cells.

There are at least two types of potato chips that have been perceived by consumers as neither low-fat chips nor traditional potato chips. One of these types is usually the “home type”
It is also characterized by the descriptive term "open pot" chips. "Homemade" chips are cooked in a batch process, rather than the continuous process commonly used for conventional chips, and are typically crisper and heavier than conventional chips. Also, while traditional chips are usually cooked in oil, “home-made” chips are
Sometimes it is cooked in lard, which is solid at room temperature. “Homemade” chips are not only highly labor-intensive to make because they are batch-processed, but product uniformity is also difficult to control, and the energy efficiency of the process is limited by the continuous process. Lower energy efficiency than can be achieved. Furthermore,
In limited regional markets, some degree of heterogeneity and variation in color, fat content and moisture content of finished foods may be acceptable for consumption, but in large domestic markets, , such variations are difficult to accept.

Another type of specialty chip that has been recognized by consumers is the so-called "Maui-style" chip. It can be seen that these chips are typically thicker than conventional chips, have more color variation, and are characterized by a firmer bite when chewing. “Maui-style” chips are processed differently than traditional chips in that the uncooked potato slices are usually not washed at all or only slightly washed before being immersed in oil. It is to be. For conventional chips, the uncooked slices are usually washed before being soaked in oil to remove surface starch. Furthermore, although continuous processing exists for Maui-type chips,
It is usually made by batch processing. The time-temperature curve for the batch cooking process of "Maui-type" chips is similar to that of a conventional one in that the temperature of the oil decreases during the first part of the cooking time and then increases during the latter part of the cooking time. It is different from chips and low-fat chips.
Its cooking time is longer than regular chips, 7 1/2
It is usually within the range of ~9 minutes. While not intending to be bound by any particular theory, in order to make "Maui-type" chips, a characteristic time-temperature curve and the particular potato used;
At least the surface starch on the thin section is required. Typically, to process "Maui-type" chips, unwashed or slightly washed uncooked slices are first placed in hot oil at a temperature of about 290-330°C (143-166°C). immersed in. Over a period of about 2-4 minutes, the temperature of the oil will drop by about 30°C (17°C), but this drop will depend on the size of the cooking equipment, the volume of the oil,
Depends on batch size and surface water. After this time, cooking continues, during which the temperature rises to about 20-30
〓(11-17℃) gradually increases. Some are
Due to the fact that "Maui-type" chips require longer cooking times and because of their unusual time-temperature cooking curves, "Maui-type" chips are typically made by batch processing. This is because conventional continuous cooking equipment produces linear, sawtooth, or gradually decreasing time-temperature curves that are unsuitable for cooking "Maui-type" chips. It is.

Accordingly, it would be desirable to provide an apparatus that is readily adaptable to the continuous cooking of various types of chips, including chips that have heretofore been primarily prepared by batch processing.

It would also be desirable to provide a method and apparatus for improving the quality of conventional potato chips, thereby allowing potatoes of lower chipping quality to be used to produce commercially acceptable chips. For example, dark or unevenly colored chips are the result of inadequate storage conditions, growing conditions and a low presence of sugar converted from starch due to certain varieties of potatoes. Therefore, to provide a device in which the cooking conditions within the cooking device can be easily varied to suit the characteristics (such as sugar content) of a particular potato in order to produce a constant and brighter color. is convenient.

It would also be desirable to be able to vary the oil content of the potato chips. For example, low fat potato chips require special processing, but the oil content can also be varied by the temperature of the oil, which is governed in part by the time-temperature relationship. Therefore,
It would be desirable to be able to easily change the temperature curve of cooking oil in a cooking device. This is because the cooking time can be easily changed.

Therefore, it would be desirable to provide an apparatus that can be adjusted or programmed to cook all types of potato chips and to handle variations in raw potatoes.

It is therefore an object of the present invention to provide an apparatus for the continuous processing of food products to be cooked, which can be adapted to provide a wide range of time-temperature curves.

Another object of the present invention is that the time period is adjustable to accommodate the solids content, sugar/starch content, and other characteristics within the raw potato to achieve a uniform and/or improved product. An object of the present invention is to provide a device that provides a temperature cooking curve.

These and other objects of the invention will become apparent from the following description of the preferred embodiments.

A continuous food processing apparatus provides the present invention, comprising: a container adapted to contain hot oil; a conveying device for controlled advancement of the food product along a predetermined path within the container; and communicating with the container. a heat exchanger external to the vessel, adapted to exchange heat with the oil to be extracted from the vessel, a device for drawing the high moisture content oil from the vessel, and a plurality of inlet devices disposed along said path from the vessel. a distribution device for recirculating withdrawn oil, the inlet device including a device for mixing the circulated high moisture content oil with oil in communication with a heat exchange device; and a device, such as a valve, for controlling the relative amount of high moisture content oil to be mixed and the oil flowing to the mixing device in communication with the heat exchange device.

One of the advantages of the present invention is that it efficiently deals with the problem of high water content oils. Cooking oils at temperatures of 275° (135°C) and above may contain water in the form of droplets. Water enters the oil both from the surface of the food and from water being expelled from the food.
The mechanism by which water is included in oil at temperatures above its boiling point is the result of several phenomena. A spherical water droplet has a small surface area compared to its volume.
When heat is transferred from hot oil to cooler water,
The surface of the water droplet changes from liquid to vapor state. During that transformation, a large amount of heat is required, approximately 970 BTU per pound of water at atmospheric pressure.
(539Kcal/Kg). When this change of conditions occurs, the surface of the water droplet becomes surrounded by steam, which is a poor conductor of heat compared to water. This vapor blanket further reduces heat transfer from the oil to the water droplets. However, if the oil is sufficiently agitated to remove the blanket of steam from the water droplets, or more importantly, if the water droplets are broken up into smaller particles, the heat transfer rate increases significantly and the steam blanket is removed from the water droplets. A rapid change of state to steam occurs.

It is important to remove most of the water from the oil before it leaves the cooking appliance and enters the oil circulation pump's suction pump. This is because the negative pressure and turbulence created by the suction law of the pump promotes locking of vapor removal from the oil and causes cavitation of the pump, resulting in damage to the pump. Also, since most pumps operate on a volumetric basis, much of the pumped volume is replaced by steam, reducing the oil mass flow rate. This situation has a significant impact on the heat exchange system due to reduced oil flow rate and localized hot spots on the heat transfer surface due to the presence of steam instead of oil. The cavitation is
Sometimes it gets so intense that oil circulation stops completely.

Systems that remove water from the oil but require large volumes of cooking oil are not practical, since minimizing the volume of oil in the system is primarily important to keeping free fatty acids in the oil low. Not.

The cooking device according to the invention can be used as a continuous cooking component in a food processing system. The cooking device according to the invention can therefore be used in combination with a slicer or with a washer and slicer combination arranged upstream of the cooking utensil. The slicer can be placed upstream of the cooking utensil, whereby the sliced raw food product is conveyed by suitable equipment and placed at the inlet end of the cooking utensil. Alternatively, the slicer can be placed above the inlet end of the utensil, whereby thin slices of the raw food product are dropped directly into the hot oil. Compatible with cleaning equipment in which the slicer can optionally be used to provide versatility in preparing washed raw potato slices for traditional pot chips or unwashed raw potato slices for “Maui-type” chips It is preferable to let
Cleaning equipment is commercially available, whereby the cleaning step may be used or the cleaning step may be omitted without changing the equipment. Downstream of the cooking utensil, a defatting device such as that described in Steden Patent No. 833,714 or US Pat. No. 3,627,535 can be used, whereby the cooking system can produce reduced fat potato chips. Also, conventional seasoning and packaging equipment can be provided downstream of the cooking utensils.

FIG. 1 shows a schematic diagram of a preferred cooking device according to the invention. Container 10 is adapted to contain hot cooking oil. Raw food is indicated by arrow 1
It is introduced into the container at the location indicated by 1. When food is cooked, it typically floats and eventually comes into contact with conveyor 12. The velocity of the oil in region A controls the residence time. Conveyor 12 transports the chips into area B, where a plurality of rotating paddles 13 soak and separate the chips.
Stir and control its advancement. Since the advancing speed of the cooking oil is usually faster than the speed of the paddle, the paddle 13 holds the chips back to provide a uniform cooking time. After the chips pass through the stirring area B,
The chips come into contact with a conveyor 14 that transfers the chips to a final area C, where the chips are conveyed through hot oil by a flighted subsurface conveyor belt 15,
holds the chips below the level of the oil while controlling their advancement through the cooking device. The cooked chips are then removed from the cooking device by the removal conveyor 15A, and at the same time,
Excess oil on the surface of the chips is drained from the product.
The total cooking time is determined by the time it takes for a particular chip to traverse the length of the container, and the temperature curve within the container may be determined by the temperature gradient (if any) along the cooking path within the container 10. Recognize.

Adjustable height weirs 12A and 14A are fitted inside the transfer conveyors 12 and 14, respectively, to control the oil level in regions A and B, respectively.
Since the amount of oil entering an area must equal the amount of oil leaving the same area, this weir allows the extra oil volume to flow from area A to area B and from area B to area C. While maintaining the oil level in the area. This feature allows much greater flexibility in adjusting the oil circulation rate in each region to achieve the desired temperature curve.

During the process of cooking potato chips, the first region within the cooking device has high levels of water in the oil as a result of water on the surface of the raw product being removed from the product during the cooking process. The reaction between oil and water (hydrolysis) reduces the useful life of the oil, so water should be removed from the oil as quickly as possible.

The apparatus shown in FIG. 1 provides a means for varying the time-temperature curve along the cooking path to substantially match a predetermined time-temperature curve, particularly a time-temperature curve having at least one slope change. A device is provided for varying the local cooking oil temperature at a point. A change in slope in the curve means that there is at least one point in the time-temperature curve where the temperature changes from increasing to decreasing or from decreasing to increasing.

Referring again to FIG. Oil discharge pipes 17A, 17B, and 17C are attached to the container 10. The oil discharged through tube 17A during the cooking process contains a significant amount of water, and somewhat less water is present in the oil discharged through tube 17B. tube 1
The oil discharged through the 7C typically contains relatively little, if any, water.
This is because cooked chips contain very little water at the end of the cooking process. Heat exchanger 19 may be a flame-fired burner or any other heat transfer device conventional in the art. Reheated oil exiting heat exchanger 19 through tube 20 is transferred to tubes 21, 22, 2
3,24 into the container 10. However, the recirculated oil in tubes 22, 23 first passes through tube 17 before entering vessel 10.
B and 17A, respectively, are mixed with high water content oils. The proportion of the mixture of oil coming from pipe 22 and oil coming from pipe 17B is controlled through valves 25 and 26, respectively, and the proportion of oil coming from pipe 23 and pipe 17A is controlled through valves 27 and 28, respectively. . A suitable pump 29 and optional filter 30 are provided. The apparatus for mixing high moisture content oil and hot oil includes components 31A, 31B, 32A and 3.
Includes 2B.

Details of 31A, 31B, 32A and 32B are shown in FIG. 1A. The high moisture content oil is forced through the distribution manifold and through a plurality of nozzles 32A. Hot oil from heat exchanger 19 is also forced through the distribution manifold and through a plurality of nozzles 32B that are larger in diameter than nozzle 32A and concentric with nozzle 32A. The rapid contact and intimate mixing of the hot oil with the high water content oil causes the dispersed water droplets to evaporate and fly away from the oil, thereby reducing the water content of the oil when it reenters the tank 10. lower. As shown, nozzles 32A and 3
2B is preferably arranged at an angle hidden in the flow of oil within the tank 10. Alternatively, the high water content oil is forced through nozzle 32B and the hot oil of the heat exchanger is forced through nozzle 32A;
Thereby, the roles of the two nozzles may be reversed.

The relative flow rates of hot oil through nozzle 32B and cooler oil through nozzle 32A control the average temperature of the oil near each inlet 32B into vessel 10. Thus, by arranging multiple inlets 32B along the cooking path within the container 10, the time-temperature curve along the cooking path can be controlled to substantially match a predetermined curve. Various temperature monitoring devices, such as thermocouples, may be placed at convenient locations to monitor the temperature characteristics of the oil.
An exemplary temperature monitoring device 33 is shown in FIG.

FIG. 2 shows another preferred device according to the invention. The difference between Figure 1 and Figure 2 is
The two streams of oil flow in opposite directions and both streams are discharged into sumps 40 and 50 in the tank comprising sections 41A and 41B. The sliced raw food is distributed by conveyor belt 42 and dropped into hot oil in tank 41A. The chips are conveyed through the cooking area A by a combination of the forward speed of the oil and the speed of the subsurface conveyor 43. Conveyor 43 also serves to separate the chips from the oil exiting through oil outlet 46 and sump 40 and 50. This active device for separating chips from the oil exiting the frying equipment allows for greater control in adjusting the flow rate of oil through intermediate inlets 56A, 56B and outlet 46 to provide the desired time-temperature curve as needed. Provide a range. When the chips exit area A, the chips are engaged by the first part of the conveyor 44 and
4 is a plurality of suspended positioning flights 4
4A actively transports chips through both area B and area C. The chips in area B may still contain sufficient moisture, and if this moisture is trapped in a small area, it will result in the formation of clumps of chips that are cooked together, so the belt of conveyor 44 The section is maintained above the oil level and only positioning flights are used to control tip movement. When the chips reach area C, the conveyor belt 44 is biased downwardly to reduce product spacing and submerge the chips below the surface of the next layer of oil where they complete cooking.

The positioning flight 44A also serves as a wiper to prevent build-up of starch or product debris on the bottom of the tank. Flight 44A of the present application is similar to that described in US Pat. No. 3,472,155.
Flights can also be attached to belt 43 to provide a similar wiper action in area A.

The cooked chips are conveyed onto a take-out conveyor 45 and discharged from the cooking device. Tank 41B
The oil in tank 41A flows downwardly into sump 50 to the left, while the oil in tank 41A flows downwardly into sump 40 to the right (see FIG. 2). The high water content oil in area A is substantially confined to tank 41A and pipe 46
and is transported by pump 47 for circulation through pipes 48 and 49 into tanks 41A and 41B. The substantially water-free oil from regions B and C which is discharged from tank 41B into sump 50 is separated by baffle 50 from the oil in sump 40 which is discharged from tank 41A. This substantially water-free oil is drawn through tube 51 by pump 52 into heat exchanger 53 where the oil is reheated to the appropriate temperature.
The reheated oil is then recycled through a network of tubes 54 into tank 41A and through tube 55 into tank 41B. The hot oil in tube 54 is mixed with high moisture content oil from tube 48 and
The hot oil from 5 is mixed with the high water content oil from line 49 by mixing devices 56A and 56B, shown in detail in FIG. 2A.

Referring to FIG. 2A, hot oil from the heat exchanger flows through the distribution manifold and through nozzle 57B. Cooler oil with high moisture content is flowed through the distribution manifold and through nozzle 57A concentric with nozzle 57B. Rapid contact of hot oil with colder, high moisture content oil causes intimate mixing, sudden expansion of water droplets, and generation and release of water vapor. As shown, inlet nozzle 57B
is perpendicular to the flow of oil in tanks 41A and 41B.

The localized temperature along the section of tank 41B is
Inlet nozzle 5 along the cooking path in tank 41B
8, this inlet nozzle 58 contains the reheated oil from the heat exchanger 53 and removes moisture in the oil before it reaches the sump 40 and pump 52. Let it evaporate. To control the local temperature within each tank 41A and 41B, various temperature control devices, such as thermocouples (not shown), are suitably placed at several locations within the tank and along various lines. It is better. The relative flow rates of hot and cold oil through the various pipes can be controlled by various valves 60.

Both devices shown in FIGS. 1 and 2 are
can be utilized in a continuous cooking process;
The cooking path through the oil is thereby controlled for a given time -
It features a time-temperature curve that can be controlled to approximately match the temperature curve. Furthermore, the apparatus shown in FIGS. 1 and 2 removes dispersed water droplets from the oil without adding extra volumes of oil to the system.

The apparatus shown in FIGS. 1 and 2 is particularly adapted to provide a continuous process for cooking food products requiring a time-temperature curve with a temperature decrease followed by a temperature increase. For example, in FIG. 3, plots of typical time-temperature and time-Btu curves for cooking "Maui-style" potato chips are shown. Although these curves were determined from a batch cooking device, these time-temperature curves are similar to those shown in Figure 1 or Figure 2.
It can be almost reproduced using the continuous cooking device shown in the figure. As seen in Figure 3,
The time-temperature curve for cooking "Maui-type" chips indicates an initial cooking temperature of about 330°C (166°C), which temperature is increased to about 304°C over a period of about 3 to 3 1/2 minutes.
(151℃). After 3-3 1/2 minutes,
The temperature increases to approximately 324°C over the next 4 1/2 minutes.
The cooked chips are removed from the oil and the temperature of the oil is allowed to rise to 330° (166°C) before starting the next batch. be done.

It will be readily apparent that various modifications may be made within the scope of the invention. In particular, in a preferred embodiment, a defatting unit can be provided downstream from the cooking apparatus shown in FIG. 1 or FIG. 2 in order to produce a food product with a substantially reduced fat content.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a preferred cooking device according to the invention. FIG. 1A shows the mixing device 31 of FIG.
It is a detailed view of A and 32B. FIG. 2 is a schematic diagram of a second preferred apparatus according to the invention. 2nd A
The figure is a detailed view of the mixing devices 50A and 56B of FIG. 2. Figure 3 shows typical time-temperature curves and times for cooking "Maui-type" potato chips.
This is a plot of the Btu requirement curve. 10... Container, 12, 14... Transfer conveyor,
15A...take-out conveyor, 19...heat exchanger,
25, 26, 27, 28... Valve, 32A, 32B
……nozzle.

Claims (1)

[Claims] 1. A container adapted to contain hot oil;
a conveyor device for transporting food along a predetermined path within the container; a heat exchange device disposed outside the container and adapted to exchange heat with oil communicating with the container; and a distribution device for recirculating the oil removed from the container through a plurality of inlet devices disposed along the path, the inlet device comprising: further comprising a device for mixing the oil communicating with the heat exchange device and the high moisture content oil, the oil communicating with the heat exchange device flowing into the mixing device and the high moisture content oil; A food preparation device including a device for adjusting the relative amount of food. 2. The mixing device includes two concentric nozzles, each nozzle receiving respectively the high moisture content stream and the oil stream in communication with the heat exchange device. The device described in. 3. The apparatus of claim 2, wherein the flow of oil within the container is parallel to the longitudinal direction of the path. 4. Apparatus according to claim 2, wherein the container accommodates two separate streams of flowing oil, the directions of each flow being opposite to each other and both parallel to the longitudinal direction of the path. . 5. successively introducing uncooked food into one end of a cooking area containing hot oil, continuously conveying said food along a path through said hot oil, and after moving said path, cooking food; is continuously removed, the path through the oil is characterized by a time-temperature curve that approximately corresponds to a predetermined curve having at least one change in the sign of the slope; Achieved by mixing high moisture content oil removed from the path with oil in communication with a heat exchange device and recirculating the mixed oil through a plurality of inlet devices disposed along the path. Continuous food preparation method. 6. The method of claim 5, wherein the food comprises potato chips.