PROCESS FOR SIMULTANEOUS FRYING AND DEODORIZATION OF THE FRYING MEDIUM

Abstract: A process for producing an improved fried snack food product is disclosed which comprises the steps of: a) frying the said food product in a suitable frying medium in a suitable frying apparatus; b) during the frying of said product, withdrawing from about 1 oil volume to about 100 oil volumes per hour of said frying medium from said apparatus and subjecting said portion of frying medium to deodorization apparatus; and c) simultaneously replacing the withdrawn frying medium of step (b) with a substantially equal portion of freshly deodorized frying medium.

Description: PROCESS FOR SIMULTANEOUS FRYING AND DEODORIZATION OF TήE FRYING MEDIUM Field of Invention The present invention relates to a process for producing fried snack food products with improved flavor, aroma, texture, appearance and/or shelf stability, comprising the deodorization of a frying medium and the simultaneous frying of said snack foods with recycled, freshly deodorized frying medium. Background The present invention relates to a process for producing fried snack food products with improved flavor, aroma, texture, appearance, and shelf stability. Said process consists of the simultaneous frying of said snack foods and the deodorization of said frying medium, thereby frying said snack foods with recycled, freshly deodorized frying medium. The oxidation of fats and oils has been a persistent problem, especially when the fat or oil is used as a frying medium and is subjected to prolonged, and/or a high degree of, heating. Oxidation of a frying medium is influenced by the amount of oxygen present, the characteristics of the frying medium, the presence of light, heat, metal contaminants and the like, and the amount of antioxidant present. Numerous chemical and physical changes occur upon the oxidation of fats and oils. For example, many and varied decomposition products including, but not limited to, aldehydes, ketones, cyclic compounds, and polymers, may be formed during the oxidation of a frying medium. In addition, there may be an undesirable change in the color of the frying medium. Finally, there may be a decrease in the iodine value of the frying medium or an increase in its viscosity, peroxide value, and free fatty acid content because of hydrolysis. These oxidation changes can decrease the fry-life of the frying medium and can increase the amount of undesirable flavors, colors, and aromas in, and decrease the shelf-life and storage stability of, snack foods fried in the frying medium. The fry-life of the frying medium may only be a matter of minutes in the presence of certain contaminants at the temperatures used for frying, e.g., 300°-500°F (149°-260°C). Many types of attempts have been made to alleviate the impact the oxidative and hydrolysis changes have in the frying process, especially on a commercial scale. One method has been to remove food particles which are left behind in the frying medium and, when the major portion of food particles have been removed, then to reclaim the reusable frying medium. Another method has been to bleed stream a small amount of the used frying medium from the fryer and either dispose of the used medium and replace it with fresh frying medium or to re-refine and/or redeodorize the frying medium and replace it with fresh oil. However, both of these methods are more wasteful and more costly than the method of the present invention. In addition, neither of those methods result in a frying medium which is as free of oxidative and hydrolysis products as that resulting from the process of the present invention. The process of the present invention combines a frying system with the simultaneous deodorization of the recycled frying medium so that the frying medium is always partially, or wholly, replenished with freshly deodorized frying medium. Accordingly, the present invention provides a process for providing fried snack food products which are substantially free from undesirable flavors, colors, and aromas and which exhibit an extended shelf-life and storage stability. In addition, the surroundings of the frying apparatus of the process is greatly improved by eliminating the need for a nearly oxygen-free nitrogen or steam blanket over the frying medium in the frying apparatus and by substantially eliminating the emission of steam or haze into the surroundings of the frying apparatus. It is therefore an object of the present invention to provide a process for frying fried snack food products whereby said snack foods are substantially free from undesirable flavors, colors, textures, aromas and appearance. It is another object of this invention to provide a process for frying fried snack food products whereby said snack foods exhibit enhanced shelf-life and storage stability. It is a further object of this invention to provide a process for frying fried snack food products wherein the need for a nitrogen or steam blanket above the frying medium in the frying apparatus is substantially eliminated. It is an additional object of this invention to provide a process for frying fried snack food products wherein the amount of haze or steam emitted into the atmosphere surrounding the frying apparatus is substantially eliminated. It is also an object of the present invention to provide a process for .frying fried snack food products wherein the need for stripping steam and/or ejector boosting steam in the deodorizing apparatus of the process is substantially eliminated. It is a final object of the present invention to provide a process for frying fried snack food products wherein the frying medium utilized therein has an increased fry-life and is substantially free of undesirable flavors and aromas and free fatty acid impurities. These and other objects of the present invention will be made clear by the disclosure herein. All percentages and ratios are by weight unless otherwise indicated. Brief Description of the Drawings Fig. 1 depicts a suitable set-up of the frying/ deodorizing system wherein the frying process is to be carried out in a continuous manner. The term "continuous frying" as used herein means that sort of frying wherein the materials to be fried are individually and continuously transported by some means through the frying vessel for a period of time sufficient to satisfactorily fry them and are then removed. As fried pieces are removed, unfried pieces continuously enter the frying.:vessel. The continuous frying/deodorizing system shown in Fig. 1 consists of a frying apparatus, a full-flow strainer, a heater, a flow-splitting device, and a deodorizing apparatus. Fig. 2 depicts suitable set-up of the frying/ deodorizing system when the frying process is to be per¬ formed as a batch process. The term "batch frying" as used herein means that sort of frying wherein the materials to be fried are placed into the frying apparatus at the same time, left there to be fried for the appropriate amount of time, and are then all removed together at the same time, i.e., in a "batch". The batch frying/deodorizing system shown in Fig. 2 consists of a frying apparatus, a full-flow strainer, a heater, and a deodorizing apparatus. Summary of the Invention The present invention relates to a process for producing snack food products exhibiting improved flavor, aroma, texture, appearance, and increased shelf-life and storage stability. Said process comprises the simultaneous deodorization of the frying medium and the frying of said snack foods with the recycled, freshly deodorized frying medium. Accordingly, the process of the present invention comprises the steps of: a) frying the said food product in a suitable frying medium in a suitable frying apparatus; b) during the frying of said product, withdrawing from about 1 oil volume to about 100 oil volumes per hour of said frying medium from said apparatus and subjecting said portion of frying medium to deodorization in a deodorizing apparatus; and c) simultaneously replacing the withdrawn frying medium of step (b) with a substantially equal portion of freshly deodorized frying medium. Said process is facilitated by a frying/deodorizing system which consists of a heater, a frying vessel into which is continuously pumped freshly deodorized frying medium, and a deodorizing apparatus into which is continuously pumped used frying medium from the frying vessel. If desired, a full-flow strainer may be utilized in the process of the present invention. A continuous flow of said frying medium is circulated, preferably, from the frying vessel to the full-flow strainer (if used), through the heater, next to the deodorizing apparatus, and then back to the frying vessel. The heater is preferably located after (i.e., downstream from) the full-flow strainer and before (i.e., upstream from) the deodorizing apparatus, but the heater may be placed anywhere in the flow order. Either a deep-fat, continuous frying apparatus or a deep-fat, batch frying apparatus may be used. The frying apparatus (i.e., the deep-fat frying apparatus, vat or vessel), and the full-flow strainer, if used, are integrated with the deodorizing apparatus so that from about 1 volume to about 100 volumes per hour, preferably from about 4 volumes to about 40 volumes per hour, of the frying medium flow is passed through the entire system. For purposes of the present invention, the "deodorizing apparatus" may consist of one deodorizer or a series of deodorizers. While semi-continuous and/or continuous deodorizers are preferred, batch deodorizers are also suitable for use herein. For purposes of the present invention, "fried snack food products" as used herein includes any food product that is subjected to frying in fats, oils, or low-calorie fatty materials at any time during its production. Said products may include fried farinaceous snack products including, but not limited to, corn chips and potato-chips. Said products may also include vegetables, cheese, or meat products which are either coated with batte and fried, or fried without a batter coating. Said products may also include certain sweet foods or confections that are subjected to frying such as donuts, Belgian Waffles, and the like. A fried snack food product particularly suitable for utilizing the process of the present invention is the chip-type potato product described in U.S. Patent 3,998,975 to Liepa (assigned to The Procter & Gamble Company), issued December 21, 1976, and incorporated by reference herein. By "low-calorie fatty materials" as used herein is meant edible materials which can replace the regular triglyceride fats present in conventional fats and oils. These materials can be used as a frying medium, just as can regular triglyceride fats and oils, yet are lower in calories because they are non-digestible, only partially digestible, or are lower in net caloric efficiency as compared to natural fats. These low-calorie fatty materials preferably include, but are not limited to, those described in U.S. Patent Nos. 3,600,186 to Mattson and Volpenhein, issued May 12, 1970; 4,005,195 to Jandacek, issued January 25, 1977; 4,005,196 to Jandacek et al., issued January 25, 1977; 4,034,083 to Mattson, issued July 5, 1977; 4,241,054 to Volpenhein et al., issued December 23, 1980; European Patent Publication 0,236,288 to Bernhardt, published September 9, 1987; and European Patent Publication 0,233,856 to Bernhardt, published August 26, 1987; all assigned to The Procter & Gamble Company and all incorporated by reference herein. "Frying" as used herein includes any type of process used to cook food products in a frying medium such as fats, oils, or other low-calorie fatty materials at temperatures of about 300°-500°F (149<>-260°C). Said frying may be pan-frying, but the benefits of the process of the present invention are greater when utilized in deep-fat frying, due to the fact that deep-fat frying has conventionally exhibited more problems associated with the oxidation and hydrolysis of frying fats and oils used as frying mediums. The frying vessel used in the process of the present invention may be of the batch or continuous type and the process may be performed in any apparatus normally used for frying, for example, pans, kettles, and deep-fat frying vessels or vats. A particularly preferred frying apparatus suitable for use in the present invention is that described in U.S. Patent 3,576,647 to Liepa (assigned to The Procter _ Gamble Company), issued April 27, 1971, and incorporated by reference herein. The "frying medium" as used herein is any fat, oil, or low-calorie fatty material used to cook a food material and includes, but is not limited to, conventional triglyceride fats such as tallow, lard, poultry fat, cocoa butter, butter, margarine, hydrogenated vegetable shortening, and also includes conventional oils such as soybean oil, corn oil, cottonseed oil, palm oil, palm kernel oil, rapeseed oil, peanut oil, olive oil, or other vegetable oils suitable for frying. In addition, certain marine oils may be suitable for use in some applications of the present invention. If desired, the frying medium may be the low-calorie fatty materials as described herein, alone or in combination with other types of frying media. The present invention is directed to a process for frying snack food products which consists of frying said products along with the simultaneous deodorization of the frying medium. Said frying medium is continuously recycled from the frying vessel through the full-flow strainer, (if used), preferably through a heater, to the deodorizing apparatus, and then, after the recycled frying medium is freshly deodorized, back to the frying vessel. As stated previously herein, the heater may be placed anywhere in the order of the flow. Detailed Description of the Drawings Fig. 1 depicts a suitable set-up of the frying/deodorizing system of the present invention wherein the frying is continuous, i.e., where the materials to be fried are individually and continuously transported through the frying vessel for a period of time sufficient to satisfactorily fry them; as the fried pieces are removed, unfried pieces continuously enter the frying vessel. As shown in Fig. 1, in the continuous frying/deodoriz¬ ing system, the dough enters the frying apparatus at the front end and is transported by some suitable means to the back end for a period of time sufficient to fry said dough. The path of the circulating frying medium through the continuous frying/deodorizing system is indicated by the unlabeled arrows. Said circulating frying medium passes through the frying apparatus to the full-flow strainer and then to the heater. The frying medium next passes through a flow-splitting device, which directs a portion of the frying medium back to the frying apparatus and the remaining portion on to the deodorizing apparatus. After said circulating frying medium is deodorized, it is directed back to the frying apparatus. As shown in Fig. 2, in the batch frying/deodorizing system, the batch of dough enters the frying apparatus and, when the frying process is complete, the batch of the fried snack food products is removed from the frying apparatus. The path of the circulating frying medium through the batch frying/deodorizing systέm is indicated by the unlabeled arrows. Said circulating frying medium passes through the frying apparatus to the full-flow strainer and then to the heater. Next, said circulating frytøg medium passes to the deodorizing apparatus where it is" deodorized, and then the freshly-deodorized circulating frying medium is directed to the frying apparatus. Detailed Description of the Invention The present invention relates to a method for producing fried snack food p « rodtf t1s which are free from undesirable flavors, aromas, texture, appearance and/or colors and which exhibit increased shelf-life and improved storage stability. This is accomplished by the continuous recycling of frying medium (whether fat, oil, or low-calorie fatty material) from a frying vessel to a deodorήzisig apparatus, and back again. Said process consists of the simultaneous frying of said snack foods and the deodorization of said frying medium, thereby frying said snack foods with recycled, freshly deodorized frying medium. ' * Accordingly, the process of the present invention comprises the steps of: a) frying the said food product in a suitable frying medium in a suitable frying apparatus; b) during the frying of said product, withdrawing from about 1 oil volume to about 100 oil volumes per hour of said frying medium from said apparatus and subjecting said portion of frying medium to deodorization in a deodorizing apparatus; and c) simultaneously replacing the withdrawn frying medium of step (b) with a substantially equal portion of freshly deodorized frying medium. Said process is made possible by the integration of the frying apparatus with the deodorizing apparatus to allow for the synchronous and continuous flow of the frying medium to the deodorizing apparatus where it is deodorized and then of the freshly deodorized frying medium back to the frying apparatus. A heater is preferably utilized in the process of the present invention to heat the frying medium as the said medium travels through the apparati utilized in the process of the present invention. Although the heater can be utilized anywhere in the order of flow, it is preferable that the heater is placed before the deodorizing apparatus. A flow-splitting device may be utilized in the process of the present invention. It is within the capabilities of one skilled in the art to decide whether the use of a flow-splitting device is suitable in any given particular design of a system utilizing the process of the present inveniton. Fig. 1 of the drawings shows the use of a flow-splitting device in the process of the present invention when the frying is performed in a continuous manner. Although the use of a flow-splitting device is not shown in Fig. 2 where the frying is batch frying, a flow-splitter may be utilized in a system utilizing batch frying. A full-flow strainer may be utilized in the process of the present invention. If the use of the full-flow strainer is desired, the frying medium flowing from the frying apparatus should first pass through the strainer before passing on to the deodorizing apparatus. If both a full-flow strainer and a heater are used, it is preferable that the heater is placed after the full-flow strainer and before the deodorizing apparatus. Accordingly, the frying medium should pass through the frying apparatus to the -11- full-flow strainer (if used), next preferably to the heater. Said frying medium should then pass through the flow-splitting device, if used, and then to the deodorizing apparatus. After said frying medium undergoes deodorization, it should pass again to the frying apparatus. The frying apparatus and the full-flow strainer, if used, are integrated with the deodorizing apparatus so that from about 1 oil volume to about 100 oil volumes per hour, preferably from about 4 oil volumes to about 40 oil volumes per hour, of the frying medium are passed through the entire system. From the standpoint of absolute quality of the deodorization and concomitant purity of the recycled frying medium, it is preferable that as many oil volumes as possible, up to 100 oil volumes per hour, of the frying medium are continuously passed through the entire system. However, to operate the system of the present invention at an increased flow rate, it is necessary to utilize more and/or larger deodorizing apparatus(i). Accordingly, from a standpoint of cost and overall economic efficiency, it is preferable that from about 4 to about 40 oil volumes of frying medium per hour is passed through the entire system. Any method known and available to one skilled in the art is suitable for use in the present invention to facilitate the route of, and to regulate the speed of, the passage of the frying medium. One particularly suitable method involves the utilization of pumps. One pump is utilized to pump freshly deodorized frying medium out of the bottom of the deodorizing apparatus and into the front end of the frying apparatus. Another pump is placed at the back end of the frying apparatus to pump soiled frying medium out of the frying apparatus into the top of the deodorizing apparatus to be freshly deodorized. If a full-flow strainer is used, the pump at the back end of the frying apparatus pumps frying medium into the full-flow strainer and a third pump may be used to pump the frying medium from the strainer to the top of the deodorizing apparatus. Any type of deodorizing apparatus (i.e., continuous, semi-continuous, or batch) may be utilized in the process of the present invention. While a batch deodorizing apparatus is suitable for use, it is not preferred for optimal operation in the process of the present invention due to the fact that batch deodorization involves the deodorization of a large quantity of a material at one time, i.e., in a batch. The integration of a batch deodorizing apparatus into a system wherein the frying medium is deodorized and simultaneously and continuously recycled into the frying apparatus is more difficult and cumbersome than the integration of a continuous or semi-continuous deodorizing apparatus into such a system.- In order to effectively integrate a batch deodorizing apparatus into the process of the present invention, a deodorizing apparatus consisting of two or more deodorizing tanks would be necessary to provide continuous flow through the system. In addition, interim storage tanks would likely be necessary to minimize the number of batch tanks necessary in the deodorizing apparatus. For the reasons set forth herein, although any type of deodorizing apparatus is suitable for use in the process described herein, the use of continuous or semi-continuous deodorizing apparatus is preferred. Various types of deodorizing apparati and methods of deodorization are described in the following U.S. Patents, all incorporated by reference herein: 2,280,896 to Dean (assigned to Foster Wheeler Corporation), issued April 28, 1942; 2,691,665 to Bailey (assigned to National Cylinder Gas Company), issued October 12, 1954; 2,743,915 to Miller et al. (assigned to National Cylinder Gas Company), issued May 1, 1956; 2,743,916 to Bornwasser (assigned to National Cylinder Gas Company), issued May 1, 1956; 2,759,883 to Thurman (assigned to Kraft Foods Company), issued August 21, 1956; 3,517,732 to Brebant (assigned to Sodeo, Societe Anonyme, Paris, France), issued June 30, 1970; 3,542,653 to Lowrey, et al . (assigned to The Procter & Gamble Co.), issued November 24, 1970; 3,933,953 to Leva, issued June 6, 1972; 4,036,865 to Hartmann et al. (assigned to Metallgesellschaft Aletiengesellschaft), issued July 19, 1977; 4,072,482 to Aoki et al . (assigned to The Nisshin Oil Mills, Ltd., Tokyo, Japan), issued February 7, 1978; Re. 28,524 to Brebant (assigned to Chemetron Corporation), reissued August 19, 1975; 4,378,317 to Seguine (assigned to The Procter & Gamble Company), issued March 29, 1983; 4,394,221 to Stage et al . (assigned to Firma Wilhelm Sch idding GmbH & Co., Cologne, Fed. Rep. of Germany), issued July 19, 1983; 4,599,143 to Stage, issued July 8, 1986; and 4,601,790 to Stage, issued July 22, 1986. Any frying medium is suitable for use in the process of the present invention. Conventional triglyceride fats and oils regularly used as mediums for frying are suitable for use herein. In addition, many classes of low-calorie fatty materials are suitable for use in the present invention. These fatty moieties typically have carbon chain lengths of 8-24 carbon atoms. Examples of such materials are as follows and are described in the following patents, all incorporated by reference herein: fatty alcohol esters of polycarboxylic acids (U.S. Patent 4,508,746 of Harnm, assigned to CPC International, Inc., issued April 2, 1985); fatty polyesters of polyglycerol (U.S. Patent 3932,532 of Hunter et al., assigned to ICI United States, Inc., issued January 13, 1976) (food use disclosed in German Patent 207,070, issued February 15, 1984)); ethers and ether-esters of polyols containing the neopentyl moiety (U.S. Patent 2,962,419 of Minich, issued November 29, 1960); fatty alcohol diesters of dicarboxylic acids such as malonic and succinic acid (U.S. Patent 4,582,927 of Fulcher, assigned to Frito-Lay, Inc., issued April 15, 1986); triglyceride esters of alpha branched chain-alkyl carboxylic acids (U.S. Patent 3,579,548 of Whyte, assigned to The Procter & Gamble Co., issued May 18, 1971); and sugar and sugar alcohol fatty acid polyesters (U.S. Patent, 3,600,186 of Mattson and Volpenhein, issued August 17, 1971; 4,005,195 to Jandacek issued January 25, 1977; 4,005,196 to Jandacek et al., issued January 25, 1977; 4,034,085 to Mattson, issued July 5, 1977; 4,241,054 to Volpenhein et al., issued December 23, 1980; European Patent Publication 0,236,288 to Bernhardt, published September 9, 1987; and European Patent Publication 0,233,856 to Bernhardt, published August 26, 1987; all assigned to The Procter & Gamble Company). Exemplary of a noncaloric fat-like material for use as the frying medium is a mixture of hexa-, hepta-, and octa-esters of sucrose and medium- and long-chain fatty acids obtained from edible fats and oils and/or fatty acid sources that are generally recognized as safe or have been approved for direct food use by U.S. Food and Drug Administration regulations. Fatty acids with chain lengths of 2 to 24, preferably 8 to 24, most preferably 14 to 18, carbon atoms can be used. A preferred material of this type meets the following specifications: (1) The total content of octa-, hepta-, and hexa-esters is not less than 95%. (2) The content of the octa-ester is not less than 70%. (3) The content of penta- and lower esters is not more than 3%. (4) Free fatty acid is not more than 0.5%. (5) Residual methyl esters of fatty acids is not more than 0.1%. (6) The residue on ignition (sulfated ash) is not more than 0.5%. (7) The free methanol residue is not more than 10 parts per million. (8) Arsenic is not more than 1 part per million. (9) Total heavy metal content (as Pb) is not more than 10 parts per million. (10) Lead is not more than 2 parts per million. (11) The viscosity is not less than 15 poise at 100°F and 10 sec -1 . -« (12) The liquid/solid stability is not less than 90% at 100 O F. The shortenings and oils used to prepare the fried snack food products made by the process of the present invention typically can contain up to and including 75%. by weight of the low-calorie fatty material. These shortenings and oils are preferably supplemented with Vitamin E at a level of 1.0 mg d-alpha-tocopherol equivalents per gram of non-caloric fat-like material. An example of a shortening made with the above- mentioned low-calorie fatty material is as follows: 35% low-calorie fatty material, 53% liquid triglyceride, 7% hardstock triglyceride, and 5% emulsifier. In particular, preferred low-calorie fatty materials of this type will contain not less than 70% of octa-esters. One low-calorie fatty material of this type " is comprised of 93.9% octa-ester, 6.1% hepta-ester, less than 0.1% tetra- and lower esters. The fatty acid composition of the low-calorie fatty material of this example is 13.i?% C\Q (palmitic acid), 41.7% Ciβ (stearic acid), 39.3% Cιs-1 (oleic acid and/or elaidic acid), 3.9% C 8-2 (ϋnoleic acid), 0.0% Cιs-3 (linolenic acid), 0.4% Ego (eicosic acid), and 1.2% of other fatty acids not listed above. A shortening could also be made with 75% of the above-mentioned low-calorie fatty material and 25% cottonseed oil; wherein the fat-like material contains 85.2% octa-ester, 14.8% hepta-ester, less than 0.1% hexa-ester, less than 0.1% penta-ester, and less than 0.1% tetra- and lower esters; and where the fatty acid composition of the fat-like material is 10.7% Cχ6 (palmitic acid), 58.8% CJS (stearic acid), 16.4% Ciβ-l (oleic acid and/or elaidic acid), 11.8% Cιβ-2 (ϋnoleic acid), 1.1% Cιβ-3 (linolenic acid), 0.5% C20 (eicosic acid), and 0.7% other fatty acids not listed above. In order to successfully practice the present invention, it is necessary to integrate the various parameters of the frying system, the full-flow strainer, (if used), and the deodorizing system with one another. For example, the oil type, the oil volume, the oil turnover rate, air exposure, and temperature are all variables involved with the frying system. The column diameter and height, type of packing, operating pressure, operating temperature, and steam or inert gas flow are all variables involved with the deodorizing system. It is well within the ability of one skilled in the art to integrate the above-mentioned variables depending upon the desired results. However, the disclosure herein will serve to supplement and enhance the knowledge of those skilled in the art relating to the practice of the present invention. The oil volume of the entire system (e.g., the frying apparatus, the full-flow strainer, (if used), and the deodorizing apparatus, and all points leading to and from and in between) depends on the overall design of the system and can be varied by one skilled in the art. The preferred volume, however, is as small as possible. The frying medium in the frying apparatus can be exposed to atmospheric oxygen contents, i.e. up to about 21% oxygen. This significantly reduces or substantially eliminates the need for a steam or nitrogen blanket over the frying medium. Of course, more passes per hour (i.e., at least 40 oil volumes per hour) going through the deodorizing apparatus is required to substantially eliminate the requirement of a steam or nitrogen blanket over the frying medium. Frying may be done with temperatures of about 300°F (1490C) to about 500°F (260OC), preferably from about 330<>F (165°C) to about 410°F (210°C), most preferably from about 350OF (1770C) to about 380<>F (193°C). The deodorizing process may be carried out at 300°F (149°C) to about 500°F (260°C), preferably at the same temperature as frying, in order to avoid added heaters and/or coolers. Sufficient deodorization at these lower temperatures is possible because the less-intense deodorization (i.e., more mild deodorizing conditions) of many passes per hour of circulating frying medium as exhibited in the process of the present invention equals the more intense deodorization (i..e., conventional deodorization conditions) of one pass of frying medium in conventionally utilized systems. The operating pressure of the deodorizing apparatus should be from about 1 mm Hg to about 500 mm Hg, preferably from about 20 mm Hg to about 100 mm Hg, most preferably from about 50 m Hg to about 100 mm Hg. There is no need for ejector booster steam due to the fact that only a mild vacuum is necessary; only a mild vacuum is necessary because of the fact that repeated passes of less intense, more mild deodorization as in the process of the present invention has the same effect as one pass of more intense, conventional deodorization. Continuous stripping steam rates should be from about 0% to about 10%, preferably from about 0% to about 4%, most preferably about 1%, at a pressure equivalent to 60-80 mm Hg and 350-380°F (177-193°C). Stripping steam rates in conventional continuous deodorizers range from about 0.5% to about 5% at pressures equivalent to about 3 to 5 mm Hg. At 60-80 mm Hg and 350-380°F (177-193 0 C), conventional continuous deodorizers would require 50% to 1000% stripping stea . The lower stripping steam rates which are useful in the process of the present invention are possible because: 1) the water dissolved by the frying medium from the wet snack food being fried aids in stripping oxidation/degradation products; and 2) the many passes per hour of circulating frying medium as exhibited in the process of the present invention equals the more intense deodorization of one pass of frying medium in conventionally utilized systems. The column diameter of the continuous deodorizing apparatus should be from about 12 in. (30.5 cm) to about 108 in. (274 cm), preferably about 24 in. (61 cm) to about 72 in. (183 cm). The packing height should be from about 6 ft. (1.8 m) to about 14 ft. (4.3 m), preferably about 8 ft. (2.4 m) to about 10 ft. (3.0 m)_. The most preferred type of packing is structural packing, such as, for example, Flexipac, Type Z, Koch Engineering Co., Inc., P.O. Box 8127, Wichita, KS 67208, although other types, including, but not limited to, Pall rings, Raschig rings, and saddles are suitable. The deodorizing apparatus should consist of about 0.1 to 4.0 Theoretical Plates, preferably about 0.5 to about 2.5 Theoretical Plates, most preferably about 2 Theoretical Plates. Conventionally, from about 5 to about 20 Theoretical Plates are necessary, but the process of the present invention permits fewer Theoretical Plates because repeated passes of frying medium from the frying apparatus through the deodorizing apparatus allows less intense stripping. Because of the high efficiency of the deodorization system and the frequent recirculation of freshly deodorized frying medium in the process of this invention, snack products having improved flavor, color, texture, appearance, aroma, and shelf-stability are produced. In addition, the process of the present invention results in many benefits in both the frying and deodorizing systems, particularly as related to cost. As stated previously herein, the frying may be done at 300°F (149°C)-500°F (260°C) and the frying medium may be exposed to atmosphere oxygen contents, i.e. up to about 21% oxygen. This eliminates the need for a nitrogen or steam blanket over the frying medium. This benefit results from repeated passes of frying medium through deodorizing apparatus. In addition, the surroundings of the frying apparatus (i.e., in a plant, the plant atmosphere) are substantially free from haze or steam resulting from the water content of the snack foods being fried. This phenomena is due to the fact that the water from the food being fried is released into the deodorizing apparatus and is there condensed as a liquid rather than being released as steam vapor into the atmosphere. There is no need for the frying apparatus to include an air handling and/or filtering system. This is because there is no net flow of non-condensable gases from the frying apparatus. In addition, the fried snack food products may be air packed, eliminating the need for costly and/or cumbersome air burners and/or for costly packaging material. Many benefits related to the deodorizing system are achieved as a result of the present invention. The plant scale deodorizing apparatus may be 6 ft. (1.8 m) to 14 ft. (4.3 m) in packing height. This size is smaller than that conventionally necessary for deodorization because repeated passes of the frying medium through the system of the present invention allows less intense deodorization. In addition, the deodorizing apparatus can use as little as zero stripping steam, as the water dissolved by the oil from the wet snack food being fried is sufficient to replace the need for stripping steam, due to the high effectiveness of the deodorizing apparatus because of the frequent recirculation of the frying medium. Further, as little as zero ejector booster steam is necessary due to the necessity of only a mild vacuum which can be produced by various methods known to one skilled in the art, such as, for example, by a water ring vacuum pump. The deodorization process may be sufficiently carried forth with temperatures of 300°-500°F (149°-260OC), which are substantially lower than temperatures normally needed for sufficient deodorization i.e., about 400°-500°F (204°-260°C). Sufficient deodorization is possible at lower temperatures in the process of the present invention because of the repeated passes of the frying medium from the frying apparatus to the deodorizing apparatus. As is evidenced by the disclosure herein, the process of the present invention produces fried snack products with improved flavor, aroma, texture, appearance, and/or shelf stability. In addition to extending the fry-life of the frying medium, the process of the present invention also results in many benefits in both the frying and deodorizing systems, particularly as related to cost. EXAMPLE 1 Process for Integrated Frying and Deodorizing Ten thousand pounds of cottonseed oil at 380°F (193°C) flows through a commercial fryer (such as that described in U.S. Patent 3,576,647 to Liepa [assigned to The Procter & Gamble Company], issued April 27, 1971) at a rate of eight hundred thousand pounds per hour. The oil enters a frying bed twenty feet long, eight feet wide, and three inches high. The bed is enclosed so as to provide a controlled atmosphere with about one percent (1%) oxygen. At the upstream end of the fryer, metal forms are attached to an endless chain and contain preformed pieces of potato dough such as that described in U.S. Patent 3,998,975 to Liepa (assigned to The Procter & Gamble Company), issued December 21, 1976. Said metal forms enter the frying oil and travel with the flowing oil for about ten seconds. The forms leave the oil and the resulting fried snack product is discharged for cooling, salting, and packing. The oil (now at 37Q° : F and containing 0.1% water, picked up from the dough being fried) continues flowing, discharging from the frying bed into a sump from which it drains through a rotating sieve which removes dough residue fragments. The oil flows into the eye of a centrifugal pump (Model No. 8X6X15C50, Allis Chalmers, Los Angeles, CA) and discharges into a flow splitting device, with sixty thousand (60,000) pounds per hour directed into the top of a packed vacuum distillation column (see U.S. Patent 3,542,653 to Lowrey, et al . [assigned to The Procter & Gamble Company], issued November 24, 1970), hereby incorporated by reference herein. The remainder of the oil is directed through a direct-fired tube 400 psig steam heat exchanger (Model No. 20-144, Atlas Industrial Mfg. Co., Clifton, NJ) where it is heated to approximately 380°F (193°C) and directed to the upstream end of the frying bed. The oil stream traveling at the rate of sixty thousand pounds per hour is metered into the top of the column and flows downward, contacting the packing. Dissolved water from the oil becomes steam and joins the upward vapor flow. The steam, non-condensible gas, off-flavor volatiles, and fatty acids pass through a demister and leave the column top at about 70 mm Hg pressure, flowing to the vacuum source through the tube side of a shell and tube condenser (see, for example, the method described in U.S. 4,406,836 to Miserlis (assigned to The Badger Co., Inc.), issued September 27, 1983, hereby incorporated by reference herein, cooled by tower water. The fatty acids are condensed and removed from a drainage vessel, while the steam and volatiles continue to a liquid ring vacuum pump (Model No. V5220, Graham Manufacturing Co., Inc., Batavia, NY) where they are condensed and discharged into the pump seal liquid. Residual non-condensible gas continues through the pump to the atmosphere. The deodorized oil is discharged from the column bottom to the eye of a centrifugal pump (Model No. GVM-IOL-IS^ Crane Company, Warrington, PA) and is then discharged into a pipe through which it flows to join the reheated oil to enter the upstream end of the frying bed.

Claims: IN THE CLAIMS: 1. A process for producing an improved fried snack food product comprising the steps of: a) frying the said food product in a suitable frying medium in a suitable frying apparatus; b) during the frying of said product, withdrawing from about 1 oil volume to about 100 oil volumes per hour of said frying medium from said apparatus and subjecting said withdrawn frying medium to vacuum deodorization at from about 1 to about 100 mm mercury in a deodorizing apparatus; and c) simultaneously replacing the withdrawn frying medium of step (b) with a substantially equal portion of freshly deodorized frying medium. 2. The process according to Claim 1 wherein the deodorizing apparatus is of the type selected from the group consisting of batch, continuous, semi-continuous and mixtures thereof. 3. The process according to Claim 2 wherein the frying medium is selected from the group consisting of tallow, lard, poultry fat, cocoa butter, butter, margarine, hydrogenated vegetable shortening, soybean oil, corn oil, cottonseed oil, palm oil, palm kernel oil, rapeseed oil, peanut oil, olive oil, low calorie fatty materials, and mixtures thereof. 4. The process according to Claim 3 wherein the low-calorie fatty material is a sugar or sugar alcohol fatty acid polyester. 5. The process according to Claim 4 wherein the low-calorie fatty material comprises a mixture of hexa-, hepta- and octa-esters of sucrose and fatty acids with chain lengths of 2 to 22 carbon atoms. 6. The process of Claim 5 wherein the total content of hexa-, hepta-, and octa-esters in the low calorie fatty material is not less than 95%, the content of the octa-ester is not less than 70%, and the content of the penta- and lower esters is not more than 3%. 7. The process according to Claim 2 wherein the frying of the fried snack food product in the frying apparatus is performed at about 300°F (149°C) to about 500°F (260<-»C). 8. The process according to Claim 7 wherein the frying apparatus is integrated with the deodorizing apparatus so that from about 1 oil volume to about 100 volumes per hour is passed through the entire frying apparatus/ deodorizing apparatus system. 9. The process according to Claim 8 wherein the frying apparatus is integrated with the deodorizing apparatus so that from 4 oil volumes to about 40 oil volumes per hour is passed through the entire frying apparatus/ deodorizing apparatus system.

Inventors: HAIR EDDY RA, HAIR, EDDY, RA
Applicants: PROCTER & GAMBLE, THE PROCTER & GAMBLE COMPANY
Application year: 1991
Main classification: C11B13
IPC codes: A23L1, C11B3