Classifications

• • A—HUMAN NECESSITIES
  • A47—FURNITURE; DOMESTIC ARTICLES OR APPLIANCES; COFFEE MILLS; SPICE MILLS; SUCTION CLEANERS IN GENERAL
  • A47J—KITCHEN EQUIPMENT; COFFEE MILLS; SPICE MILLS; APPARATUS FOR MAKING BEVERAGES
  • A47J37/00—Baking; Roasting; Grilling; Frying
  • A47J37/12—Deep fat fryers, e.g. for frying fish or chips
  • A47J37/1223—Deep fat fryers, e.g. for frying fish or chips with means for filtering the frying liquid
• • A—HUMAN NECESSITIES
  • A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
  • A23L—FOODS, FOODSTUFFS OR NON-ALCOHOLIC BEVERAGES, NOT OTHERWISE PROVIDED FOR; PREPARATION OR TREATMENT THEREOF
  • A23L5/00—Preparation or treatment of foods or foodstuffs, in general; Food or foodstuffs obtained thereby; Materials therefor
  • A23L5/10—General methods of cooking foods, e.g. by roasting or frying
  • A23L5/11—General methods of cooking foods, e.g. by roasting or frying using oil
• • A—HUMAN NECESSITIES
  • A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
  • A23L—FOODS, FOODSTUFFS OR NON-ALCOHOLIC BEVERAGES, NOT OTHERWISE PROVIDED FOR; PREPARATION OR TREATMENT THEREOF
  • A23L5/00—Preparation or treatment of foods or foodstuffs, in general; Food or foodstuffs obtained thereby; Materials therefor
  • A23L5/20—Removal of unwanted matter, e.g. deodorisation or detoxification
  • A23L5/23—Removal of unwanted matter, e.g. deodorisation or detoxification by extraction with solvents

Definitions

• This invention relates to the production of fried foods and more particularly to the removal of a portion of the residual oils and fats remaining in fried foods after frying and to the resulting food product.
• snack food items such as potato chips, potato sticks, corn curls, onion rings, doughnuts and the like are prepared by frying or cooking either vegetable materials, e.g., potatoes, onions, etc., or doughs, e.g., masa doughs, breadlike doughs etc., in hot fats.
• vegetable materials e.g., potatoes, onions, etc.
• doughs e.g., masa doughs, breadlike doughs etc.
• the food products pick up and retain relatively large amounts of the fats and oils.
• a typical potato chip may contain about 40 weight percent residual oil and fat, which can be a mixture of glycerides, fatty acids, aldehydes and ketones.
• the typical potato chip also contains 5 to 6% protein, about 50% carbohydrates and about 2 to 4% moisture.
• Fats and oils are glycerides (fatty acid esters of glycerol) of animal and vegetable origin which contains varying amounts and types of fatty acids. During storage of the fats and oils and during the cooking and frying operations, the glycerides undergo further breakdown leading to the formation of free fatty acids, aldehydes and ketones. These various chemical species can exhibit positive and negative effects on the flavor characteristics of the fried food product.
• the invention accordingly comprises the several steps and the relation of one or more of such steps with respect to each of the others, the apparatus embodying features of construction, combinations and arrangements of parts which are adapted to effect such steps, and the article possessing the feature, properties and the relation of elements, which are exemplified in the following detailed disclosure, and the scope of the invention will be indicated in the claims.
• Fig. 1 is a plot of solubility as a function of the pressure of supercritical carbon dioxide at 55°C of a commercially available highly refined vegetable oil, the supercritical carbon dioxide serving as an example of one form of fluidic solvent state extractant for the practice of this invention;
• Fig. 2 is a diagrammatic representation of the test apparatus used in treating various fried foods in accordance with the method of this invention.
• Fig. 3 illustrates diagrammatically exemplary apparatus for the practice of this invention integrated with apparatus for deep-fat frying.
• a method of removing from a fried food product at least a portion of the fats introduced therein during frying comprising the steps of contacting a fried food product containing fats absorbed therein during frying with an extractant which is normally a gas but is in a fluidic solvent state for the fats and which is nontoxic and inert with respect to the fats, thereby to dissolve at least a portion of the fats in the extractant; and separating the resulting treated food product from the extractant containing the fats dissolved therein, thereby to provide a defatted fried food product which retains the textural mouth feel of the fried food product and which has a lower caloric content and a higher nutrient value than the fried food product.
• a modified fried food product characterized in that at least a portion of the fats introduced therein and absorbed thereby during frying has been removed by contacting the fried food containing the fats with an extractant which is normally a gas but is in its fluidic solvent state for the fats and which is nontoxic and inert with respect to the fats, thereby to dissolve at least 10% by weight of the fats in the extractant, and subsequently separating the resulting treated food product from the extractant containing the fats dissolved therein; whereby the modified fried food product has a higher nutritive value and lower caloric content on an equal weight basis than the unmodified product.
• an apparatus for preparing a low-fat fried food product comprising in combination frying means containing frying oil at a predetermined temperature; means for introducing a raw food product to be fried into the frying means and means for withdrawing the resulting fried food product from the frying means; pressure vessel means; means to convey the fried food product containing fats absorbed from the oil from the frying means to the pressure vessel means; means to circulate an extractant, which is normally a gas under temperature and pressure conditions rendering the gas a fluidic state solvent for the absorbed fats, through the pressure vessel in contact with the fried food product contained therein to transfer at least a portion of the fats from said fried food product to the extractant and to produce a low-fat fried food product; means to withdraw the low-fat food product from the pressure vessel means; means to withdraw the extractant containing dissolved fats from the pressure vessel means; means to subject the extractant containing the dissolved fats to a physical treatment which renders the extractant
• glycerides, fatty acids, aldehydes and ketones which comprise the cooking oils used and which are absorbed during cooking and hence removed by the treatment of this invention will generally be referred to as "fat” or “fats”, the term being used in its broadest sense to include both these fatty acids and glycerides.
• the extractant used in the practice of this invention to remove a portion of the cooking fats is a relatively low molecular weight material, e.g., not over about 150, which is in a gaseous state at normal pressure and temperature and which can be converted to a fluidic state, e.g., a liquid or supercritical fluid, by subjecting it to a combination of pressure and temperature which changes its physical state.
• Carbon dioxide in its fluidic solvent state within the temperature and pressure ranges stated is the preferred extractant in treating fried foods in accordance with the practice of this invention.
• the characteristics of carbon dioxide in its fluidic solvent state which make it desirable for this invention are that it is inert to the food products, is a solvent for the fats to be removed, is nontoxic, is readily and completely removable, and does not detract from the flavor or texture of the resulting treated food products. Any extractant used in accordance with this invention should have these characteristics. Carbon dioxide is, moreover, relatively inexpensive and easily handled without contributing any problems for safety or environmental pollution.
• Patent 3,923,847 fats from grains and the like (U.S. Patent 3,939,281); residual hexane from de-fatted grain (U.S. Patent 3,966,981); and a variety of materials such as paraffins, glycerol, oils and fats from a variety of compositions (U.S. Patent 3,969, 196).
• Fig. 1 As exemplary of the solvent capability of carbon dioxide, the solubility in fluidic carbon dioxide at 55°C of a typical, commercially available, highly refined vegetable oil similar to those used in deep fat frying is plotted in Fig. 1 as a function of pressure. It will be seen from Fig. 1 that when carbon dioxide is maintained at a temperature of about 55°C and a pressure of about 135 atmospheres or greater, an appreciable amount of oil can be extracted. However, the conditions used in plot Fig.
• FIG. 2 A number of commercially available fried foods were treated in accordance with this invention by contacting them with supercritical carbon dioxide at 55°C and 4000 psi (272 atmospheres).
• the apparatus used in these experimental tests is shown diagrammatically in Fig. 2.
• Accurately weighed quantities of the various fried foods to be treated were introduced at ambient temperature and pressure into a chamber 10 defined within a pressure vessel 11 as layers, e.g., layers 12-17, stacked therein.
• the pressure vessel used comprised a Schedule 160 stainless steel pipe six inches long and two inches in outside diameter. It was closed on both ends with pressure- sealed caps 18 and 19.
• a valve-controlled high-pressure fluid inlet line 20 and a valve-controlled high-pressure fluid discharge line 21 were in fluid communication with chamber 10.
• Carbon dioxide gas under about 1000 psi from a supply cylinder 22 was compressed by compressor 23 to the required 272 atmospheres and the temperature of the compressed carbon dioxide adjusted in heat exchanger 24.
• the fluidic state carbon contacted the food product of stack 12 first, then that of stack 13 and so on. Subsequent to its contacting the topmost stack, the extractant fluid was discharged through line 21, expanded through valve 26, passed into vessel 25 and discharged to the atmosphere, the solvate constituting the fats, along with a minor amount of moisture which had been removed in treating the food products was collected in vessel 25. No attempt was made to convert the carbon dioxide to its fluidic solvent state and recirculate it. In commercially-scaled apparatus this can, of course, be done by altering either the pressure and/or the temperature of the extractant fluid to make it a nonsolvent for the fats and hence to form two phases which can readily be separated.
• the potato chips and potato sticks thus treated were tasted by five trained flavor analysts who found the treated products to be crispy and to have a well defined potato flavor. Moreover, the treated products appeared to become crispier with increasing fat removal. It was determined by the flavor panelists that these treated products essentially maintained the necessary delicate balance between fat and potato taste to make them acceptable to consumers.
• the method of this invention is also applicable to fried foods formed from breadlike dough, e.g., doughnuts or similar products. This will be apparent from the data in Table 5 which were obtained using the apparatus of Fig. 2.
• the layers in the pressure vessel were alternately a doughnut and a doughnut dough product formed when the hole is cut in the doughnut, i.e., a doughnut hole shape.
• Apparatus for preparing a low-fat fried food product in accordance with this invention is illustrated diagrammat ically in Fig. 3.
• the raw food to be processed 30 e.g., sliced raw potatoes, masa dough cut into designed shapes, etc
• the raw food to be processed 30 is carried by a conveyor 31 from a product supply 32 to a frying means 33 containing frying oil 34 at a predetermined temperature.
• the fried food product 35 is taken out of the oil by suitable conveyor means 36 and carried by further conveyor means 37 to the pressure vessel 38 through which the fluidic extractant is circulated to contact the fried food product 35.
• the treated, low-fat food product 39 is withdrawn from pressure vessel 38 through a chute 40 having a pressure valve 41 and taken, subsequent to the addition of salt and any other desired flavoring, by conveyor 42 to a packager 43.
• the fluidic extractant is provided to vessel 38 through a conduit 44, the fluid flow through which is controlled by valve 45; and it is withdrawn from vessel 38 by means of valve- controlled conduit 46.
• Valve 47 in conduit 46 is of the type which effects expansion and pressure reduction of the extractant. As a result of this expansion the dissolving power of the extractant is decreased with resultant formation of two phases, namely a nonsolvent fluid and the fats extracted from the food product in vessel 38. It may be desirable to raise the temperature of the nonsolvent fluid at least to that point where the fats remain an easily pourable liquid. This may be accomplished in an out-of-contact heat exchanger 48 with the use of an externally supplied heat transfer liquid supplied through line 49.
• the nonsolvent fluid 51 is separated from the liquid fat 52, the former being withdrawn through line 53 having valve 54 and the latter through a line 55 having valve 56.
• the gas which is to be converted to its fluidic solvent state is originally provided from a cylinder 57 through line 58 and valve 59 to main line 60 with which the recovered non-solvent fluid line 53 is connected.
• the fluid in line 60 is then taken into pump/compressor 61 for compression to the pressure desired for the fluidic solvent state. If it is necessary to adjust the temperature of the extractant fluid, this may be done in heat exchanger 62 by circulating a heat exchange liquid through line 63 in out-of-contact heat exchange with the fluid prior to its entering line 44. It is, of course, within the scope of this invention to combine heat exchangers 48 and 62, using the circulating fluids as all or part of the heat exchange liquids in the system.
• the fats recovered in separator 50 can be returned through line 55 to a frying oil supply 65 from which the quantity of oil in frying means 33 is replenished. Makeup oil from supply means 66 may also be added. Under some circumstances it may be desirable to add certain components, e.g., fatty acids, to the recycled fats from separator 50 to balance the various constituents in the frying oil. This may be done in mixing means 67 which is an optional apparatus component.
• a typical batch operation as illustrated in Fig. 3 it would be desirable to have several treating units 70 (enclosed in the dot/dash line) associated with each frying unit so that the frying operation could proceed continuously.
• the treating is begun by filling pressure vessel 38 with fresh fried chips and the closing valve 47 in chute 40 as well as valves 47, 54 and 56.
• carbon dioxide is supplied from cylinder 57 through line 58, valve 59 and line 60 to pump/compressor 61. Once the system has been provided with sufficient carbon dioxide, it will usually not be necessary to draw any more carbon dioxide from cylinder 57 than that required to make up any losses.
• valve 45 is closed, valves 47 and 54 are opened and when sufficient fat 52 has accummulated in separator 50, valve 56 is opened. If pressure or gravity feed of fat 52 from separator 50 is not feasible then line 55 may have a liquid pump associated with it. Valve 41 in chute 40 is opened to allow the chips to be discharged for delivery to packager 43. With the completion of the discharge of the chips from vessel 38, the cycle is begun again.
• Fig. 3 may be designed to provide continuous, rather than batch, treatment of the fried food product.

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• Engineering & Computer Science (AREA)
• Food Science & Technology (AREA)
• Chemical & Material Sciences (AREA)
• Health & Medical Sciences (AREA)
• Nutrition Science (AREA)
• Life Sciences & Earth Sciences (AREA)
• Polymers & Plastics (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Preparation Of Fruits And Vegetables (AREA)
• General Preparation And Processing Of Foods (AREA)
• Bakery Products And Manufacturing Methods Therefor (AREA)
• Frying-Pans Or Fryers (AREA)

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Citations (8)

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• 1981
  • 1981-10-02 JP JP56503331A patent/JPS57501660A/ja active Pending
  • 1981-10-02 BR BR8108827A patent/BR8108827A/pt unknown
  • 1981-10-02 WO PCT/US1981/001327 patent/WO1982001118A1/en not_active Application Discontinuation
  • 1981-10-02 EP EP19810902851 patent/EP0060884A4/en not_active Withdrawn

Patent Citations (8)

Non-Patent Citations (2)

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