Method for controlling puffing of a starch-containing snack food product and fried snack product

Abstract: This invention relates to a method for controlling puffing of a starch-containing snack food product during cooking where the product is made from a dough piece formed as a thin sheet, wherein the dough sheet is dockered by contacting it with a flexible bristle brush prior to cooking the dockered dough piece, the flexible bristles forming small holes in the dough piece to allow for the escape of steam during cooking sufficiently to avoid puffing in the finished product. A preferred fried snack product is made from a thin sheeted starch-containing dough piece wherein the fried snack product has a number of barely discernible dockering holes extending through the depth of the product in a random pattern which varies uniquely from product to product and in which the fried products in the aggregate are essentially free of surface bubble formation.

Description: BACKGROUND OF THE INVENTION Snack products of thin, relatively flat shape have unique advantages in processing and marketing as a consumer product. Potato chips, for example, are well-known snack products prepared by frying thin slices of raw fresh potatoes. Because of their thin dimension, water is rapidly removed from the potato slices during frying, forming a snack product with crisp texture and a fresh potato flavor. Extruded and sheeted fried snack products made in a thin, flat shape from ground precooked corn have the same advantages of fast frying to an acceptably low moisture content and a crisp texture. Many processes have been developed for producing thin fried snack products from a dough which is prepared, formed and cut into desired shapes, and then fried. An especially large number of processes have produced such fried snacks from a potato-based dough, but none has had the commercial success of fresh potato chips. A number of these potato-based processes are described in my U.S. Patent 3,886,291, from column 1, line 35 to column 3, line 23. When making fried snacks from thin, flat dough pieces, there is a tendency for the dough piece surfaces to separate and puff during frying. In snack products made from a dough with a reasonably high moisture content, say in the 35% to 60% range, it is desirable to produce a thin, uniformly expanded product upon frying. Normally frying such a thin moist dough piece produces large surface bubbles in the fried product. Such puffing or bubbling occurs because steam accumulates between the outer surfaces of the dough pieces during frying, especially in sheeted dough pieces when multiple reduction rolls have been used. Puffing and bubbling detract from the appearance of the finished snack and can cause the snack to fill with excess fat. Such separation or distortion of dough pieces in the fryer has also been referred to in the art as "pillowing" or "blistering", but the terms puffing or bubbling are used interchangeably herein for convenience to describe any of these phenomena. A number of processing techniques have been devoted to reducing puffing in thin sheeted fried snacks. U.S. Patent 2,905,559 to Anderson et al. describes a conventional "dockering" technique in which a corn masa dough sheet is perforated with small rigid spikes spaced about 3,2-12,7 mm (1/8 to 1/2 inch) apart. The perforations allow moisture from the dough to escape during frying, which avoids puffing of the finished fried product: U.S. Patent 3,278,311 to Brown et al. discloses a process for making corn chips in which corn particles are forced through a plasticizer having a screw grinder with a perforated end plate. The plasticized dough is sheeted and then dockered, cut into pieces and fried in oil. U.S. Patent 2,916,378 to Kunce et al. relies on coarsely ground corn in ordinary corn chips so that the dough surface is disconnected and the steam from within the dough can readily escape during frying to avoid puffing. U.S. Patent 3,883,671 to Shatilla describes a process for reducing puffing by moistening the surfaces of flat dough pieces with water after forming and before frying. Other methods reported to reduce puffing include forming dough pieces with a corrugated surface, and forming the dough pieces in very thin layers of about 0.4 mm (0.016 in.) thickness. Attempts to reduce puffing in thin, flat fried snack products by mechanical dockering with rigid metal pins supported on cylindrical rollers have generally not been successful because the relatively large openings formed in the dough create an untypical appearance in the finished snack product. The products appear artificial because the large dockering holes have an identical pattern or a uniform repeat pattern in all of the finished snacks. Attempts to control puffing by spraying water on the dough pieces can cause the pieces to become slippery and stick together during frying. Water spraying also requires more energy for subsequently removing the added water; and it forms a product with a hard, less desirable texture after frying. The present invention provides a novel dockering technique that produce single layer and double layer finished products without undesired puffing or bubbling, while avoiding water spraying and problems associated with dockering rolls having rigid metal pins. The dockering method also avoids other problems resulting from dockering techniques of the prior art. In addition, use of the dockering method produces novel fried products. SUMMARY OF THE INVENTION The method according to the invention for controlling puffing of a starch-containing snack food product during cooking where the product is made from a dough piece formed as a thin sheet is characterized in that the dough sheet is dockered by contacting it with a flexible bristle brush prior to cooking the dockered dough piece, the flexible bristles forming small holes in the dough piece to allow for the escape of steam during cooking sufficiently to avoid puffing in the finished product. This results in a fried snack product made from a thin sheeted starch-containing dough piece which is characterized in that the fried snack product has at least 3 (20) completed holes per cm² (square inch) of surface area extending throuh the depth of the product in a random pattern which varies uniquely from product to product and in which the fried products in the aggregate have a Bubble Index below 30. Briefly one embodiment of this invention comprises use of a novel semi-flexible bristle dockering brush for perforating the dough layer prior to frying the dough pieces. This permits dough pieces of a relatively high moisture content to be fried to completion without undesirable puffing or bubbling. The sheeted dough is perforated by a rotating cylindrical brush having radially extending semi-flexible bristles. In one embodiment of the invention, the distance between the brush and the dough sheet conveyor belt is adjusted to apply pressure to the tips of the bristles to pre-flex the bristles prior to the dockering step. This allows the bristles to bend when forming the dockering holes in the dough sheet. In another embodiment, the brush is operated at a slower speed than the traveling dough sheet during dockering. These techniques control the point density of dockering holes formed in the dough and prevent the dough from wrinkling or tearing when contacted by the dockering brush. The flexible dockering brush can have a bristle point density of about 12-31 points/cm² (80 to 200 points per square inch) of peripheral brush surface, for certain products. A dough sheet contacted by such a dockering brush would contain from about 12-31 (80 to 200) dockering holes per cm² (square inch) if contacted by brush tips of the same length and if all brush tips formed holes extending completely through the depth of the dough sheet; but in practice the number of discrete perforations extending entirely through the dough sheet is less than the actual brush point density of the flexible bristles. From about 20 to about 100 perforations per square inch or more can be formed through the entire depth of the dough sheet. Surface indentations also are formed in the dough. This high density of small dockering holes and surface indentations eliminates undesired puffing or bubbling during frying, and yet the dockering holes are hardly noticeable in the finished product. Inasmuch as fewer than all of the bristles form completed holes, the dockering hole pattern is unique for each fried dough piece, which avoids the artificial appearance of the uniform hole pattern and large dockering holes resulting from rigid pin dockering. These and other aspects of the invention will be more fully understood by referring to the following detailed description and the accompanying drawings. DRAWINGS FIG. 1 is a schematic view illustrating a dough preparation, sheeting and fryer system for producing a single layered fried snack product according to principles of this invention. The fryer is not shown to scale. FIG. 2 is a schematic view illustrating a system for producing a bi-layer potato skin snack. The fryer also is not shown to scale and is schematic only. DETAILED DESCRIPTION Dough suitable for making fried snack products is prepared from conventional snack food ingredients. The dough is sheeted to a desired thickness, dockered with a flexible brush, cut to the desired shapes, and fried by a float-frying process. Such a process for making fried snack products from a single layer dough sheet is described with reference to FIG. 1. A two-layer fried snack product is made by a process described with reference to FIG. 2. The dockering process which is described below is used to prevent puffing during frying in the float-frying process. Said dockering technique can be used to prevent distortion or puffing of fried or baked starch-containing dough products. Flexible Brush Dockering Dockering is a traditional operation in the bakery industry where products such as saltine crackers are perforated at regular intervals to control expansion of the finished product and to achieve a uniform appearance. A process for dockering corn chips is described in U.S. Patent 2,905,559 to Anderson et al. This dockering device uses sharp pointed spikes spaced on centers between 0.32 cm and 0.64 cm (1/8 inch and 1/4 inch) apart. The spikes have a diameter of 1.6 mm (0.063 in.). We have found that the flexible bristle brush provides significant advantages over dockering with rigid metal spikes or pins. A wide spacing between larger diameter rigid metal spikes or pins is unsatisfactory for the thin sheeted snack products of this invention. The flexible bristle dockering brush eliminates the possibility that metal particles can break from the sharp pointed dockering pins and become lodged in the finished product. Another advantage is the ability to form a larger number of closely spaced holes and point impressions in the surface of the finished snack. Such dockering is highly effective in reducing puffing in thin sheeted fried snacks made from a moist dough. A further advantage is that the brush points can have a smaller diameter so that the perforations in the finished product are not readily apparent. We have found, for example, that thin, semi-flexible 0.020 inch (0.51 mm) diameter nylon or polypropylene bristles, when distributed at the periphery of the brush at about 12 (80) to 21 (140) points per cm² (square inch) of peripheral surface, perforate the dough substantially uniformly. That is, a large number of small discrete holes or indentations are formed across the surface of the dough sheet in a reasonably uniform pattern. Puffing during subsequent frying is greatly reduced in the finished fried product, and any small discrete holes that penetrate the entire depth of the fried pieces are virtually impossible to detect. However, the semi-flexible bristles form a discrete hole pattern in the finished product which is entirely random, i.e., unique from chip to chip. Because of the variations in length inherent in the flexible bristles and because the bristles flex during dockering, the number of holes per unit area formed in the dough sheet by the bristles is less than the actual point density of the bristles at the periphery of the brush. With a preferred point density of about 21 (140) bristles per cm² (square inch), for example, the actual number of holes formed in the dough sheet (before frying) varies from about 105 (70) to about 18 (120). The number of discrete holes extending through the entire depth of the fried piece is lower. Generally speaking, the number of completed holes formed in the fried product, per unit area, is directly proportional to reduced bubbling in the finished product. Thin fried snack products having more than about 3 (20) completed holes per cm² (square inch) are essentially free of undesired puffing or bubbling. We have also discovered another significant difference between the dockering method used in this invention and dockering as used in the baking industry. Conventional dockering rolls normally have the same diameter as the rotary cutter which follows the dockering roll. A single drive is used to achieve the same peripheral speed for both rotating units. For example, a 12-inch rotary cutter nay be used with a dockering device of 12-inch maximum diameter at the tip of the rigid metal perforating units. With a belt speed of 18.3 m/sec. (60 feet per minute), both the cutter and dockering roll rotate at 19.09 rpm, producing the same peripheral velocity of 18,3 m/sec. (60 feet per minute) for the cutter and perforating roll . I have discovered that with the thin sheeted dough products of this invention, the peripheral velocity of the dockering points, if separately variable, can be controlled in relation to dough velocity to produce optimum perforation of the dough and positive release of the dough sheet from the dockering brush. Good results are obtained when the peripheral velocity of the dockering brush is from about 45% of the linear velocity of the dough sheet up to about 100% of the dough sheet velocity. Optimum results are produced when this relative velocity is in the 70% to 95% range. Further description of the use and advantages of the flexible brush dockering techniques is set forth in examples below. Examples The following Examples 1 through 7 describe flexible brush dockering. EXAMPLE 1 A series of tests were conducted in the pilot plant described below to eliminate puffing during frying through the use of a flexible bristle dockering brush. For the following tests the dough formulation and frying procedure were the same as described below, except that the water spray unit was not used to moisten the surfaces of the cut dough pieces. A continuous pilot plant for making bi-layered potato snacks was installed as follows. A first set of adjustable feed rolls placed light colored dough on the first section of a sheeting line conveyor. A second set of feed rolls placed a separate, darker colored dough on top of the lighter dough, and the two dough layers were conveyed under a second pair of sheeting rolls. The width of the combined dough sheets was approximately 35.6 cm (14 inches). The initially sheeted layers were then compressed in the first of two sets of reduction rollers. The final set of reduction rollers reduced the total dough thickness to within the desired 0.50 mm (0.02 in.) to 1.0 mm (0.039 in.) range. A rotary cutter mounted over the final conveyor cut the bi-layer dough into oval shapes. The unused dough web was then recovered with an overhead conveyor which transferred the web to a transverse collecting conveyor. The cut dough pieces were deposited on an optional conveyor having water spray nozzles above and below the belt that conveyed the pieces between the sheeting equipment and the fryer. The cut dough pieces dropped onto an input conveyor leading to a single stage fryer through which heated oil was circulated by a centrifugal pump. The dough pieces were not fried in a shallow depth of oil; in this experiment the dough pieces were fried in a conventional deep fat fryer. The fryer had an external electrically heated heat exchanger and an oil bypass by which the flow through the fryer pan could be adjusted. One or two adjustable speed paddles distributed the product uniformly across the width of the fryer. An adjustable speed submerger belt held the products beneath the oil surface for the remainder of the frying time. A final take-out belt conveyor deposited the fried samples in suitable containers. Each of the feed rollers and reduction rollers could be separately controlled to the desired thickness, after which corresponding speed adjustments were made in the interconnecting conveyors. The speed of the final product conveyor leading to the fryer was normally maintained between about 5.49 and 12.2 m/min. (18 and 40 feet per minute); at about 9.45 m/min. (31 feet per minute) the line capacity was about 120 pounds per hour of fried product. The oil depth in the fryer was about 7.5 cm (three inches) and the oil temperature at the inlet was 350°F. Two 18-inch wide rotating paddles distributed the dough pieces across the width of the fryer. The submerger belt length and speed produced a total frying time of about 65 seconds. A mixture of dry ingredients for the light colored dough was prepared, and a separate mixture of dry ingredients for the darker colored dough was prepared. The formulation for the lighter dough included about 38.3% potato flakes, 36.8% potato starch, 1% sugar, 0.6% salt, 0.4% MSG, 0.3% paste-type 40% monoglyceride emulsifier, 2.6% liquid soybean oil, and 20% ground cooked white corn, all expressed on a 10% moisture content basis. The ground cooked corn was prepared as follows. Dry corn was cooked for 40 minutes in a steam jacketed kettle with approximately 200% water based on the weight of corn. The corn was soaked overnight in excess water at 90°F., rinsed lightly, and ground in a Urschel Comitrol using a 0.010030 cutting head. Either yellow, white or combinations of both corn varieties were used. A purpose of using the corn solids in the dough was to provide sufficient discontinuity in the sheeted product to reduce puffing upon subsequent frying. Conventional lime treatment to remove hulls was not practiced when making the ground cooked corn described herein. 100 parts of the light dough formulation were added to 50 parts of water. The dark dough included 35.8% potato flakes, 10% ground dehydrated potatoes, 36.8% potato starch, 2.5% dried potato peels, 1% sugar, 0.6% salt, 0.4% MSG, 0.3% emulsifier, 2.6% soy oil, 1.5% liquid caramel color, 10% ground cooked corn, and 55% water relative to the dry mix. The dry ingredients were blended in a ribbon blender until they were uniformly distributed. For the lighter dough, the ground corn, containing about 50% moisture, and water were added to the dry mix and mixed two minutes at slow speed with the flat paddle in a 57ℓ (60-quart) Hobart mixer. For the dark dough the liquid caramel color was added to the water before adding to the dry mix; alternately, dry caramel color could be mixed with dry ingredients for the dark dough. The lighter dough was first sheeted to between 1.0 mm and 1.8 mm (0.039 and 0.07 in.), optimally 1.4 mm (0.055 in.), and deposited on the first conveyor. The dark dough was sheeted to between 1.0 mm and 1.6 mm (0.039 and 0.063 in.), optionally 1.3 mm (0.051 in.), and deposited on top of the light dough sheet. The double layer was then reduced in thickness to approximately 1.0 mm to 1.3 mm (0.039 to 0.051 in.) through the first reduction rolls, and then from 0.85 mm to 1.10 mm (0.033 to 0.043 in.), normally 0.95 to 1.0 mm (0.037 to 0.039 in.), through the second reduction rolls. The recycled web was added at a fixed ratio to the dark dough, normally 35%, after first grinding it (in a Reitz hammermill fitted with sharp blades) into random pieces from approximately 0.51 cm (0.2 inch) to 2.54 cm (1.0 inch) in diameter. The recycled dough web was added to the dark dough during the last 30 seconds of mixing so that small portions of the lighter uncolored layer remained intact and exposed in the dark upper surface of the sheeted dough, producing a mottled appearance. An experiment was conducted to determine techniques to controlling puffing of the product using a water spray to moisten both sides of the sheeted dough pieces before frying. Test 1A. A 7.0 cm (2.75 inch) outer diameter polypropylene bristle brush was installed in the pilot plant described above for use as a dockering device. The brush was located midway between the final sheeting rollers and the cutter so that the dough sheet was perforated with a number of small, barely discernible holes before cutting. The length of the bristles was about 2,3 cm (0.9 inch) measured from the point at which they emerged from the metal tape on the brush cylinder to the tip of each bristle. The diameter of each bristle was 0.46 mm (0.018 inch). The bristles were spread apart relatively uniformly by rotating the brush against a moving surface. The brush was rotated so that its point of contact with the dough sheet moved in the same direction as the traveling dough web. The brush had 55 (140) bristles per linear cm (inch) of the metal tape and there were 10,5 (32) turns per m (foot) of the tape on the shaft, from which it was calculated that the density of bristles at the peripheral surface of the brush was about 22 (141) bristles per cm² (square inch). The brush was mounted between two adjustable height bearings on opposite sides of the product conveyor. The brush was driven at the same speed as the conveyor by a rubber roller wheel installed on the same shaft. Considerable difficulty was encountered during this test because the dough sheet tended to wrap itself around the flexible bristles. Test 1B. The brush described in test 3A was fitted with a separate independent variable speed drive. It was observed that the optimum rotational speed of the brush was different from the predicted speed established by the velocity of the dough sheet. It was observed that the velocity of the ends of the bristles, or the peripheral velocity, should be adjusted for varying conditions of dough consistency and also according to the velocity of the dough sheet on the final conveyor. For example, in making the product described in Example 2, optimum puncturing of the dough sheet and release of the dough from the bristles were obtained when the tip velocity of the bristles (in a direction parallel to the travel of the dough sheet) was 12% slower than the linear velocity of the dough sheet. When the output velocity was increased by increasing the conveyor belt speed from 408.4 cm/min. (13.4 feet per minute) to 707.1 cm/min. (23.2 feet per minute), the rotational speed of the brush also changed to 10.5 rpm, or 6.19 m/min. (20.3 feet per minute), at the tip of the bristles, a 25% difference. Test 1C. Various bristle materials and construction methods were studied in preparation for construction of a larger pilot plant dockering brush. Nylon bristles 3.3 cm (1.30 inches) long were obtained with diameters of 0.46, 0.51 and 0.56 mm (0.018, 0.020 and 0.022 inches). The holes in the dough sheet made with 0.56 mm (0.022 inch) bristles were too obvious in the final product, and the longer 0.46 mm (0.018 inch) bristle was too flexible, so the 0.51 mm (0.020 inch) diameter bristle was chosen. The peripheral point density of the bristle points was reduced to 20.2 points per sq. cm (130 points per square inch), which was found sufficient to penetrate the dough sheet and produce final products in which 72% of the products had bubbles less than 6 mm (0.24 in.) in diameter, 28% bubbles 6 mm to 12 mm (0.47 in.) in diameter, and no bubbles over 12 mm diameter. Subsequent tests and adjustments made it possible to lower the 6 to 12 mm bubble count to between 10% and 20%, which was judged excellent quality for production. The dockering brush had an overall outer diameter of 19.18 cm (7.55 inches) and was operated at a peripheral velocity (in a direction parallel to the traveling dough sheet) 15% to 25% slower than the linear velocity of the dough sheet. The speed of the dough sheet was 18.3 m/min. (60 feet per minute). Test 1D. A dockering brush useful for production of fried snack products was designed to produce results comparable to those produced with the pilot plant brush used in Test 3C. A production line was designed to produce a dough sheet 152.4 cm (60 inches) wide. A dockering brush having a diameter of 19.8 cm (7.8 inches) was used. A point density of 19.4 points/cm² (125 points per square inch) for the dockering brush was chosen to conform to the pilot plant operation. In subsequent pilot plant tests, it was found that with a point density less than about 12.4 points/cm² (80 points per square inch) too many large surface bubbles were present in the finished fried snacks. With a point density exceeding about 31.0 points/cm² (200 points per square inch), the dough sheet became torn or wrapped around the dockering brush due to the excess pressure required to force that many dockering points through the dough sheet and the additional force required to remove the dough sheet from that many bristles. The dockering brush was constructed as follows. A 1.27 cm (1/2 inch) U-form galvanized metal tape was used for the production dockering brush. It was filled with a white nylon material (sold by DuPont under the tradename Tynex) having a diameter of 0.51 mm (0.02 inch), ± 10% and HD crimped (deep crimped in a hank). Crimping improves the life of the material by absorbing a portion of the flex from the bristles during use. The brush was constructed with a fill of 0.361 gm/cm (11 gm of bristles per foot) of tape. For this material, this was equivalent to 39.37 bristles/cm (100 bristles per lineal inch) of the metal holding tape. This is the lightest possible fill with conventional brush forming equipment to prevent scissoring of the bristles and inconsistent fill. The tape machine was set to close the "U-form" holder as tightly as possible to flare the bristles during the brush formation. The "U-form" brush was immediately wrapped at 0.787 turns/cm (24 turns per foot) on a 11.43 cm (4.5 inch) diameter mandrel, producing a cylinder diameter of 12.38 cm (4.875 inches). This wrap was tight and uniform to prevent creep or voids when the brush was placed in operation. The bristles were then turned to length by a scissor-type action, leaving a chisel point, which was later sanded with 120-160 grit emery cloth to round the ends and prevent or minimize dough sheet pick-up. After forming, the brush was placed on bearing mounts on the sheeting line and trimmed to the cutter width on each end, using a dremel-type craft saw with a rotary speed of about 20,000 rpm. In spite of the tight wrap holding the bristles, some ridges of less density existed in the finished brush. It was found that a more uniform brush could be obtained by warming the rotating bristles using a quartz heater suspended approximately 7.62 cm (3 inches) above the tips of the bristles. The brush was lowered about 0.635 cm (1/4 inch) below the point at which the bristles first touched the surface of the conveyor belt. The belt was then driven at a speed of about 457 to 610 cm/min. (15 to 20 feet per minute) for about one hour. The bristles were allowed to heat to facilitate their spreading action but were maintained at a temperature under 116°C (240°F), at which point they would start to soften or distort. The formed nylon bristles had an average length of 3.71 cm (1.46 inches) and an average diameter of 0.051 cm (0.020 inch). In use it was found that the dockering brush should be mounted at a level that pre-flexes the bristles. That is, the brush was mounted so that the minimum spacing between the fixed inner ends of the bristles and the top surface of the dough sheet conveyor belt was less than the unflexed length of the bristles. This mounting of the brush applies a force to the outer periphery of the bristles which pre-flexes the bristles. Thus, the bristles are constantly in a flexed condition when contacting the moving dough sheet during the dockering step. In the following test, the dockering brush was lowered to a level 0.8 to 1.6 mm (1/32 to 1/16 inch) below the point where the tips of the bristles first touch the belt. The pre-flexed brush was then used to docker the dough sheet traveling on the belt. The brush was driven by a drive separate from the conveyor belt drive so that the speed of rotation of the brush could be adjusted relative to belt speed. The dockering brush was rotated in a direction that rotated the tips of the bristles in the same linear direction in which the dough was traveling at the locus of contact between the tips of the bristles and the dough sheet. As the bristles and dough sheet met, the bristles entered the dough sheet at a slightly obtuse angle of about 115° from the horizontal axis. The sheet traveled slightly faster than the bristles, which drew the bristles in the direction of brush rotation, bent the bristles, and then caused them to rotate at their tips, as they continued to penetrate the sheet. Since the bristles flex during contact with the moving dough sheet, they formed elongated holes in the dough sheet. The length of the holes was parallel to the direction in which the dough sheet traveled. Although the dockering holes were elongated, they were barely discernible to the naked eye, and in the finished fried product they were barely noticeable. The dockering holes appear as small random dots or points in the finished product rather than larger holes in a definite pattern. After the brush was put into operation, it was demonstrated that the flexible bristles at the bristle length of 3.7 cm (1.46 inches) and the 0.51 mm (0.020 inch) diameter produced good results when the dockered dough pieces were subsequently fried. The bristles had the proper stiffness to penetrate the dough sheet and eliminate blistering or bubbling of the finished fried product. The random small discrete openings in the surface of the finished snack did not detract from the natural appearance of the snack. That is, they were not readily apparent and formed in a unique random pattern from chip to chip. Continuous operation for 24 hours per day for months of operation was accomplished with this dockering brush without problem; and good finished products with minimal bubbling were consistently produced. For other dough compositions, other brush stiffness factors such as length, diameter and material can be selected by those familiar with the art to accomplish similar dockering of the dough sheet. Examples 2 through 7 describe in more detail the improved results using the production dockering brush. As to the method for calculating the number of bristles per square inch of peripheral brush surface for the pilot plant and production brushes, the following data are pertinent: Mandrel = 4.5" OD Height of 1/2" U-form tape after wrapping = 0.1875" Mandrel + U-form tape = 4.875" = D₁ Bristle fill per ft. of tape = 11 gm ≅ 100 bristles/inch = C Wraps of tape per ft. of mandrel = 24 = T Outside diameter of pilot plant brush = 7.48" = D₂ Outside diameter of production brush = 7.8" = D₂ Number of points per square inch of brush cylindrical area = N EXAMPLE 2 The procedure of Example 1 was used for a number of tests of various processing variables. For these tests the dockering brush described in Example 1 was used along with a two-stage pilot float fryer. Test 2A. A 283ℓ (ten cubic foot) Marion mixer, model 6021, was obtained for pilot plant production of larger quantities of dough. The mixer was fitted with a 3600 rpm chopper to facilitate cutting and mixing the recycled dough web without requiring a hammer mill. A 114 kg (250 pound) batch of light colored dough was prepared by blending 57 kg (125 pounds) of blended dry mix with the ground yellow corn in the mixer without the chopper for 30 seconds at 50 rpm. While still mixing, 28,9 kg (63.5 pounds) of water were added and the mix continued until the dough was uniform, in about three more minutes. For the dark initial dough, 64 kg (141 pounds) of dry mix and 13,5 kg (30 pounds) of ground yellow corn and 812 grams of dry caramel were blended for 30 seconds with the paddles only. While still mixing, 35,5 kg (78 pounds) of water were added and the mix continued for an additional three minutes. After a period of operation sufficient web was accumulated for mixing with the next batch of dark dough. The mixer was charged with 27,5 kg (56.5 pounds) of dry mix, 5,55 kg (12.2 pounds) of yellow ground cooked corn and 38,7 kg (85 pounds) of dough web which were mixed 30 seconds with the chopper operating. While the mixing continued, 14,2 kg (31.3 pounds) of water were added and the mix continued for 2.5 minutes, after which the remaining 29,6 kg (65 pounds) of unground web were added and mixed an additional 30 seconds with the chopper. A sample of the dough was examined and it was found that the web had been broken up into pieces, the largest of which was about 1.9 cm (0.75 inch) in diameter. The sheeted dark dough had a desirable mottled appearance as the result of incorporating portions of the bi-layer dough during the final portion of mixing step. Pre-blends were made of the potato flake granules and other minor dry ingredients for the light dough and also for the dark dough, including a dry caramel color. The pre-mix was added to the remaining dry ingredients, emulsifier oil and ground corn in a Stephan mixer for 15 seconds, after which the water was added over a period of 30 seconds and the mix continued another 30 seconds for a total mix time of 75 seconds. During mixing, the hand-operated stirring bar was rotated to remove particles of dough that stuck to the side of the bowl. The initial dark dough was mixed in exactly the same sequence. For the subsequent dark doughs, including 35% recycled dough web, the dry pre-mix, ground corn and one-half of the dough web were mixed in the Stephan mixer for 15 seconds, and the water was added during 30 seconds continued mixing, followed by an additional 20 seconds of mixing. The mixer was turned off, the remaining one-half of the web was added, and the mix continued for only an additional 10 seconds. The ratio of 35% web to 65% new dark ingredients is the quantity that was estimated would be useful for commercial production. Test 2B. A 40 liter Stephan mixer equipped with a cutting blade mounted on a vertical shaft turning at 1800 rpm was used to prepare both the dark and light dough fractions described above in Test 2A. It was found that mixing time was significant. For example, with a light dough containing about 43.5% moisture, extending the mixing time an additional 10 seconds created a dough which was adhesive and was difficult to remove from the sheeting rolls and the surfaces of the cutter. In addition, the product puffed excessively upon drying even though the dockering brush was used. EXAMPLE 3 Using substantially the same formula and procedure as described in Example 2B to prepare a dough having a moisture content of about 42% by weight, the effects of variations in speed between the dockering brush and the dough sheet were measured. A double-layer product was tested. The dockering brush described in Example 1C was used. Before beginning this test, the dockering brush bristles were pre-flexed by lowering the brush to a level where the bristles, if extended straight, would have been about 0.9 mm (0.035 inch) below the top surface of the dough conveyor belt. This setting of the brush was maintained throughout the tests in this example. The conveyor belt carrying the two-layer dough sheet through the dockering brush and cutter assembly was operated at a speed of 262.2 cm/min. (8.6 feet per minute). The peripheral speed of the brush was adjusted over a wide range and was expressed as a percentage of the belt speed, where brush speed was measured in a direction parallel to conveyor belt travel. When brush speed was increased to a speed slightly greater than the speed of the dough sheet, the brush began to tear the dough sheet and dough pieces were picked up and carried over by the brush. As the speed of the brush was decreased relative to the speed of the dough sheet, the indentations of the bristle points became fewer but more obvious, until brush speed was reduced to about 50% of the dough speed. Below this speed, the dough sheet became wrinkled and exhibited a considerable number of torn enlarged holes. During this test, samples of the dockered dough sheet were removed and examined to count the number of dockering holes in the surfaces of the dough pieces. This examination was made by exposing the dockered dough sheet to illumination from a lamp to facilitate counting the number of discrete holes penetrating the entire depth of the dough sheet. Such discrete holes cannot be seen with the naked eye without back lighting. As the rotational speed of the dockering brush was decreased, the number of dockering holes per square inch in the top surface of the dough sheet also decreased. However, as brush speed was reduced relative to dough speed, the added flex of the bristles tended to form more elongated holes, and penetration through the dough sheet tended to increase. As a result, the number of completed holes in the finished products can be similar for a range of acceptable brush speeds. The finished fried products were examined for bubble count to determine the amount of fried products having reduced bubbling or puffing within a commercially acceptable range. The amount of bubbling in the finished fried snacks was measured by a Bubble Index determined as follows. 100 grams of chips were divided into chips having only bubbles less than 6 mm in diameter (category A); chips having any bubbles within a range of 6 to 12 mm in diameter (category B); and chips having any bubbles more than 12 mm in diameter (category C). The chips within each category were weighed. The weight of chips within category A was multiplied by zero, the weight of chips within category B was multiplied by 0.5, and the weight of chips within category C was multiplied by 1.0. The resulting figures for the three categories were added to produce the total Bubble Index. Category C products are considered undesirable. However, a certain amount of bubbling produces good end products. Bubbling within the category B range is permissible and can be desirable. For instance, thin sheeted single layer products can have good crispness and texture if some bubbling is present. A Bubble Index of less than about 30 for a production sample of thin single layer chips is considered desirable. However, this index can vary with the product. A Bubble Index less than about 20 is desirable for the two-layer snacks. The finished fried products also were examined for fat content and expansion ratio. Product expansion remained at about 1.66 to 1.75 throughout the test. Fat content varied from about 25% to 27%. It was concluded that the relation between dockering brush speed and dough speed for the workable range of relative speeds did not have a significant affect on expansion or fat content, both of which were within acceptable ranges in this test. As shown in the test results, Bubble Index did not change significantly over a wide range of brush speeds. Higher brush speeds can produce more dockering holes per unit of surface area of the dough, but as brush speed decreases, the greater flex of the bristles forms larger holes and produces better penetration. As a result, brush speed can be set within the limits of high speed and low speed operation which ensure smooth dockering of the dough sheet, and within those limits the resulting Bubble Index is generally acceptable. In a separate test, the surface of the dockering brush was raised above the surface of the dough sheet. Without dockering, the number of chips having any bubbles over 12 mm diameter was 93% of the total; and the number of chips having any bubbles 6 to 12 mm in diameter was 7% of the total. Bubble Index was 97. The appearance of the fried product changed considerably as dockering brush speed was decreased to about 64% of belt speed and below. Samples of finished fried products were graded on a five point scale, in which 1 is excellent, smooth appearance, 3 is the limit of acceptability, and 5 is the worst. As the brush speed was reduced, the dough sheet became extremely wrinkled and folds developed in the dough at about 50% to 55% of belt speed and below. In addition, the number of torn enlarged holes caused by the slowly rotating dockering brush points increased considerably. While some degree of wrinkling may be tolerated to produce a more natural appearance to the surface of the fried snacks, operation with an excessively low brush-to-dough relative speed becomes unacceptable because of the tendency of the dough to wrinkle and fold. If a wrinkled fried product is desirable, such a product can be produced by operating the brush at a speed of about 10% to 15% above the lower acceptable limit of brush speed. Of course, this range can vary from product to product and can be determined in relation to dough thickness, composition and moisture content. It was concluded that the optimum relative speed of a brush for making a two-layer potato skin snack without any unacceptable surface wrinkling or tearing of the dough is between about 70% to 95% of dough sheet speed. It was concluded that these factors (avoiding wrinkling and tearing of the dough) control the acceptable relative speed of the dockering brush relative to belt speed more than other factors such as bubble count, fat content, or expansion of the finished products. EXAMPLE 4 The procedure described in Example 3 was repeated to measure the effect of the height of the dockering brush tips relative to the dough sheet. At the beginning of the test, the brush was lowered to a level of operation where the bristle tips would have been 0.9 mm (0.035 inch) below the top surface of the conveyor belt. As the brush height was adjusted, measurements were made of the distance between a fixed point on the conveyor support and the bottom of the rotating shaft. These were then converted into the brush depth measurements described in Table 8. The brush was raised slightly so that brush depth was reduced to 0.25 mm (0.01 inch). A larger number of undesired bubbles were noted in the finished product. The brush was then lowered gradually for a series of tests made at brush depths from 0.9 mm (0.035 inch) to 3.4 mm (0.135 inch). This latter depth of penetration produced the maximum amount of pressure that could be applied to the brush to flex the bristles as they encountered the dough sheet. It was concluded that operation with greater brush depths would create excessive wear of the brush. The fried product was examined over a source of illumination to count the number and judge the appearance of the small holes formed by the dockering brush. Table 8 shows the number of holes in the top and bottom surfaces of the fried products and the Bubble Index for 100 gram samples of the finished products. Optimum results were obtained with brush height in the range of 0.15 mm (0.06 inch) to 3,43 mm (0.135 inch). Generally, the amount of dockered holes that penetrated entirely through the dough were directly related to a reduction in the Bubble Index. Since the number of discrete holes increase with a certain level of pressure applied to the dough sheet by the brush, producing a corresponding reduction in the Bubble Index, it was concluded that operation with a certain level of brush pressure is desirable for these types of products. It has been determined that the best procedure for operating the flexible dockering brush is to first determine the desired depth of penetration to achieve optimum reduction of bubble size in the finished product. This setting can be made depending upon dough characteristics such as dough thickness, composition and moisture content. Once the optimum reduction in the Bubble Index is produced, the desired relative brush-to-belt speed is then set to prevent tearing (at high speeds) and to avoid wrinkling of the dough (at low speeds). Relative speed settings between these limits do not significantly affect bubble size or other quality measurements in the finished products. EXAMPLE 5 A single layer sheeted potato snack was made from a dry mixture of potato ingredients having the following approximate formulation: Potato flakes-36%; potato granules-13%; ground dehydrated potatoes-7.5%; potato starch-37%; vegetable oil-3%; paste-type monoglyceride emulsifier-0.3%; the balance being various flavoring ingredients including sugar, salt, MSG, etc. The potato flakes were blended with the oil, emulsifier, and minor ingredients in a 60-quart Hobart mixer and then the other dry ingredients were added and mixed 5 minutes. Water was added to the dry mix and mixing continued for 2 minutes on speed 2 with the paddle blade to prepare a dough with a moisture content of about 42% by weight. The friable potato mixture was fed to a set of 6.5-inch (2.56 cm) diameter, 12-inch (4.72 cm) wide, stainless steel sheeting rolls, after which the sheeted dough was conveyed through the flexible bristle dockering brush and cutting system. The dockered dough sheet was cut into hexagon shapes using a polyethylene cutter with a spacing of about 2 inches (5.08 cm) between opposite parallel sides. The dockered and cut pieces were then fried to completion at 350°F in a single stage continuous fryer. The dockering brush was set at the same level as in Example 3. The effect of variation of the dockering brush speed was measured with the dough sheet first sheeted to about 0.70 mm (0.028 in.) thickness and later to a thickness between 0.95 and 1.00 mm (0.037 to 0.039 in.). As noted in Example 3, operation of the brush with a peripheral speed maintained at about the same speed as the dough sheet, or slightly above, was limited by the tendency of the dough sheet to tear apart and stick to the brush. By slowing the dockering brush (relative to belt speed) by controlling the separate drive for the brush, the bristles flexed during perforation of the dough sheet so that the sheet released from the bristles with little or no sticking. As the speed of the brush was progressively reduced, the force on the dough sheet from the slowly moving bristles eventually caused the sheet to wrinkle to a degree which finally became impractical. Table 3 summarizes the measurements made during the experiment and the effects on the quality of the finished product. There were no measurable differences caused by the variation in dockering speed on fat content, expansion and bulk density of the finished product. The Bubble Index for the thin sheet product was higher than for the thicker product. During this test, the dockering brush had been raised slightly to avoid tearing the fragile dough of the thinner sheeted product, which resulted in fewer dockering points penetrating the dough sheet. From the results of this experiment, and particularly because of the wrinkled appearance of the product at the slowest speed and the tendency of the dough sheet to tear and adhere to the brush at faster speeds, it was concluded that for sheeted potato products the practical lower limit of dockering brush speed was about 60% of belt speed for thin products and 50% for thicker products, and up to a maximum of about 106% of the brush speed for both dough thicknesses. Optimum limits for product quality and machine operation are from about 70% to 95% of belt speed, similar to the results of Example 3. As in Example 3, brush speed also can be maintained at about 10% to about 15% above the lower acceptable limit of brush speed to form an intentionally wrinkled product. Thus, good products can generally be produced when brush speed is in the range from about 50% up to about 100% of dough speed. EXAMPLE 6 A non-limed ground cooked corn ingredient was made from dry yellow corn as described in Example 1. The cooked corn was soaked overnight in 32°C (90°F) water, drained and ground through the Comitrol using the 1030 head. The approximate formulation contained 64% ground cooked corn (calculated on a 10% moisture basis), 15% pregelatinized corn flour, 15% amioca corn starch, 10% potato flakes and 0.6% salt. The moisture content of the ground gelatinized corn was 50% and the moisture of the dough was 49%. The ingredients were mixed in a HObart VCM 40-liter mixer fitted with sharp cutting blade impeller. The dry ingredients were mixed with the corn for 15 seconds, water was added, and mixing was continued for an additional 45 seconds on low speed. The dough was sheeted to produce a single layer dough, and the effects of dockering were tested for thin and thicker single layer products. The dough was sheeted through a single set of 16.5 cm (6.5 inch) diameter stainless rollers set to produce a 0.9 mm (0.035 in.) dough thickness in one sample and 0.75 mm (0.03 in.) thickness in a second sample. The dough sheet was dockered with the nylon brush described in Example 1C set at the brush depth described in Example 3. The sheet dough was cut into equilateral triangles with sides approximately 5.8 mm (2 inches) long. The cut dough pieces were fried continuously at 177°C (350°F) for about 60 seconds and were later evaluated for quality. During this test the belt speed was maintained at 246.9 cm/min. (8.1 feet per minute) for the thinner dough and 253 cm/min. (8.3 feet per minute) for the thicker dough sheet. The brush speed was varied between the ranges described in Examples 3 and 5, from the fastest speed at which the brush could be operated without tearing and wrapping the dough sheet around the brush, to the slowest speed where wrinkling of the dough sheet made further operation impractical. Results of these tests are shown in Table 4. Variations in the speed of the dockering brush had substantially no effect on product expansion, fat content, bulk density and breakage. Extreme wrinkling of the dough sheet was noted at each thickness as the brush approached the minimum speed. Wrinkling was more pronounced than with potato snacks under the same conditions. As the speed of the brush was increased and approached the speed of the dough sheet, the degree of puffing was reduced because of additional holes penetrating through the dough sheet. In general, the corn snack was more difficult to make than potato-based snacks because of dough stickiness. It was concluded that the optimum range for sheeted corn snacks made with the flexible dockering brush was at a relative speed from about 70% to about 95% of dough sheet speed. EXAMPLE 7 A potato-based dough similar to that described in the previous examples was sheeted to a final dough thickness of 0.7 mm and dockered by the flexible bristle dockering brush set at a brush depth of 1.52 mm (0.06 inch). Results of the test demonstrated that best dockering brush operation occurred at a brush speed of 94% of the dough speed. Good product results were also obtained for brush speeds lower than 94% and for brush speeds up to about 100% of dough speed. The dough began to wrinkle at 85% of dough speed, but the wrinkles were barely perceptible in the finished product. Wrinkles were visible in the finished products when the dough was dockered at a brush speed of 60%. The wrinkles were small amplitude undulations extruding essentially parallel to each other across the width of the fried piece. The undulations were best visible when the finished product was viewed in cross-section. Brush operation could not be sustained at speeds below about 40%. It was concluded that good intentionally wrinkled products could be produced for this thin sheeted single layer product at brush speeds in the 50% to 60% range. The Bubble Index was well within the acceptable range. Better intentionally wrinkled products were produced for thin sheeted single layer products than for the thicker double layer products. A wrinkled product can have improved crispness and texture when compared with some products which are not wrinkled. Thus, use of the flexible dockering brush makes it possible to avoid unacceptable puffing or bubbling when frying thin sheeted dough pieces (generally in the range of 0.6 mm to about 1.2 mm) with a high moisture content (generally in the range of about 35% to about 60% by weight) having a combination of gelatinized and ungelatinized starch contained in the dough at the time of frying. Frying such a dough piece without dockering consistently produces unacceptable bubbling in nearly all of the fried products. Acceptable finished products can be consistently produced with the flexible dockering brush in at least 95% of the finished products. This improvement can be achieved without moisture treatment before frying or other prior art dockering techniques. Improvements also are produced when compared with dockering using rollers with rigid dockering spikes or pins. Use of the flexible dockering brush has shown that bubbling is reduced in proportion to the point density (holes per area of sheeted dough) of completed holes formed in the dough by the dockering brush (when the brush is used within the practical limits for the distance between the brush and conveyor belt and for brush speed versus belt speed). The bubble count in finished products is acceptable for single and double-layer products and for corn and potato-based dough products. The necessity of using the flexible dockering brush is more critical when producing thin single-layer fried snacks. Flexible brush dockering also produces commercially acceptable fried snacks which are deep-fat fried entirely, i.e., without initial frying in the shallow depth float-frying method. Use of the flexible dockering brush also has a number of processing advantages over use of the dockering roll with rigid dockering pins. The flexible bristles can be pre-flexed to bend during dockering and apply a pre-set pressure to the dough sheet. The usable length of rigid dockering pins is limited to not greater than the distance from the roll to the belt surface. Since the flexible bristles can be longer and can bend while dockering, this has an advantage of producing a longer locus of contact with the dough sheet, thereby forming elongated dockering holes which allow the bristles to release better from the dough and thereby avoid the dough sticking to the brush or otherwise deforming the dough. A greater density of dockering points also can be used on the flexible dockering brush compared with rigid dockering pins. The use of rigid dockering pins at greater point densities can create problems of sticking and deformation of the dough sheet. Because of the greater point density made possible with the flexible dockering brush, depth of penetration is improved, producing more dockering holes per unit area of sheeted dough. Since the greater point density of completed holes produces a related reduction in bubbling, the flexible dockering brush is highly effective in producing acceptable finished products. Other advantages of the flexible dockering brush include producing a random pattern of dockering holes in the finished products and the capability of producing an intentionally wrinkled finished product. Operation of the dockering brush at speeds within certain limits can, in combination, produce necessary dockering to control surface bubble formation and to obtain a wrinkled appearance in the finished product. Examples herein have shown that a point density in the range of about 12 (80) to about 31 (200) holes per cm² (square inch) produces acceptable finished products with minimal bubbling, while permitting the dockering brush to be operated smoothly on the sheet product. Point densities lower than about 12 (80) holes per cm² (square inch) can produce too many bubbles in the finished product. Point densities greater than about 31 (200) points per cm² (square inch) can cause too much wrapping of the dough on the bristles of the dockering brush. The range can vary depending upon dough composition, thickness and moisture content. Inasmuch as baked starch-containing dough products are also dockered prior to heat-treatment to reduce puffing, it is believed that the flexible dockering brush of this invention also can be used for baked products. One advantage is that the dockering holes can be less apparent and have a random hole pattern in the finished product which is unique from piece to piece.

Claims: Method for controlling puffing of a starch-containing snack food product during cooking where the product is made from a dough piece formed as a thin sheet, characterized in that the dough sheet is dockered by contacting it with a flexible bristle brush prior to cooking the dockered dough piece, the flexible bristles forming small holes in the dough piece to allow for the escape of steam during cooking sufficiently to avoid puffing in the finished product. Method according to claim 1 characterized in that the perforations produced by the dockering brush in the dough piece are in a random pattern and have a point density less than the point density of the bristles on the brush. Method according to any of claims 1 or 2 characterized in that the peripheral velocity of the bristles at their point of contact with the dough sheet is variable relative to the linear velocity of the dough sheet. Method according to claim 3 characterized in that the peripheral velocity of the bristles is lower than the linear velocity of the dough sheet. Method according to any of claims 1 to 4 characterized in that the point density of the bristles contacting the dough sheet is in the range of about 12 (80) to about 31 (200) points per cm² (square inch). Method according to any of claims 1 to 5 characterized in that the dockering brush is operated at a speed relative to dough speed that forms a wrinkled dough piece. Fried snack product obtainable by the process of claims 1 to 6 and made from a thin sheeted starch-containing dough piece, characterized in that the fried snack product has at least 3 (20) completed holes per cm² (square inch) of surface area extending through the depth of the product in a random pattern which varies uniquely from product to product and in which the fried products in the aggregate have a Bubble Index below 30. Product according to claim 7, characterized in that the finished product is wrinkled.

Inventors: WILLARD MILES JAMISON, WILLARD, MILES JAMISON
Applicants: JAMISON WILLARD MILES, WILLARD, MILES JAMISON
Application year: 1991
Main classification: A23L1
IPC codes: A23L1, A21C11