JP2015023917A - Electrode structural body of fryer for food material, and method to fry food material by using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fryer and a method to fry food materials which are to drastically prolong cooking oil's life span, drastically cut down frying time, and drastically improve deterioration of the oil, while achieving quickly frying fries which, for a long time, can keep good mouthfeel and merits, such as things that they can be fried crispy, keeping crispy even after a long time, they do not lost their crispy texture after rewarmed with a microwave oven, and so on.SOLUTION: A food fryer includes an electrode structural body which possesses electrodes to apply electric voltage to cooking oil during frying food materials. The food fryer fries the food materials in a prescribed range of temperature by heating the cooking oil in its oil tank. Films which consist of a material with a low work function are provided on the surfaces of the electrodes of the electrode structural body.

Description

  The present invention relates to a fryer electrode structure for frying food such as deep-fried food and a method for frying food using the same.

  As the development of fast food stores, convenience stores, department store foodstuffs, fried confectionery, etc. progress, so-called large fryer that can cook large amounts of fried chicken, croquettes, cutlets, tempura, potato fries, etc. Demand is growing significantly. As a result, the amount of edible oil used in the fryer has increased, and disposal of the used oil has become a major issue from the viewpoint of environmental protection and ecology.

  In order to reduce the amount of edible oil used for fried food as one of the solutions to this problem, it is highly expected from an ecological point of view that the service life of edible oil will be greatly increased and the frying time will be shortened.

  The service life of edible oil depends on factors such as oxidation, decomposition, mutation, and alteration of oil (hereinafter collectively referred to as “oil degradation”).

  In addition, fried foods are required to have a good texture such as being deeply fried, crispy even after a long time, and crispy feeling is not lost even if heated again with a microwave oven or the like.

  In order to prevent deterioration of edible oil when using a fryer, for example, a plate-like electrode is arranged on the bottom of the fryer oil tank, and a negative high voltage potential is applied to the electrode to form a high electric field in the oil liquid in the oil tank. There is an example that, when the food is fried in such a state, there are effects such as suppression of oil oxidation, prevention of contamination, and shortening of the frying time (Patent Document 1).

  There is also an example in which the arrangement of plate electrodes is devised to prevent deterioration of edible oil when using a fryer (Patent Document 2).

  There has also been a proposal to improve the shortening of the frying time by arranging a long and narrow electrode in the oil liquid in the oil tank and applying a high frequency to the electrode (Patent Document 3).

JP 2001-95695 A JP 2004-41531 A JP 2006-102447 A

  However, the fryer electric field forming device described in Patent Document 1 is configured to charge the bottom of the oil tank with an electrode extending over the entire bottom surface of the oil tank. It is not uniform, and it is not rare that frying spots of ingredients occur.

  In Patent Document 2, since the electrode is arranged in parallel to the side wall of the oil tank, the problem of Patent Document 1 is avoided, but since the electrode extends along the vertical direction, sufficient thermal convection in the lower part in the oil tank is achieved. There is a problem that it can't happen.

  In the fryer electric field forming apparatus of Patent Document 3, it is said that the problems of Patent Documents 1 and 2 have been solved, but it has been proved that the inventors have not achieved a dramatic solution by experimental verification of the present inventors. .

  That is, the close contact between the food and the bottom of the oil tank is avoided, but in the case of a large fryer, the heat convection on the back side of the food is not necessarily sufficient, and the heat convection is uniform in the oil liquid in the whole oil tank. There is no guarantee that it will be in a uniform fried state at any time. In addition, the deterioration of the oil is not sufficiently prevented, and even if a high frequency AC voltage is applied, the heat transfer in the oil tank is promoted, but the frying time is not reduced so much. .

  The present invention has been devised in view of the above points, and one of its purposes is to provide a fryer and a method for frying food that can easily increase the service life of edible oil and greatly shorten the frying time. Is to provide.

  Another object of the present invention is to improve the texture and its goodness for a long time, such as being crisp, crispy even after a long time, and crispy feeling is not lost even if it is heated again with a microwave oven etc. It is to provide a fryer and a method for frying foods, which can deeply maintain a deep-fried food that can be fried in a short time by greatly improving the deterioration of oil.

  Still another object of the present invention is to provide a fryer and a method for frying foods, which can surely meet the first object even when applied to a large fryer.

  One aspect of the present invention is an electrode surface for forming a high-voltage electric field in a cooking oil that is used in a food fryer that heats cooking oil in an oil tank and fries the food in a predetermined temperature range. An electrode structure for a food fryer having a low work function material film on the electrode surface.

  According to another aspect of the present invention, the electrode structure is embedded in oil injected into an oil tank of a food fryer, and a frying operation process is performed while applying a DC negative potential or an AC potential to the electrode structure. It is in the method of frying the food characterized by doing.

  According to the present invention, the service life of edible oil can be greatly increased and the frying time can be greatly shortened, and it is crisp even after a long time. Deep-fried food that can maintain its good texture for a long time, such as not losing, can be fried in a short time with greatly improved oil degradation

  Other features and advantages of the present invention will become apparent from the following description with reference to the accompanying drawings. In the accompanying drawings, the same or similar components are denoted by the same reference numerals. The accompanying drawings are included in the specification, constitute a part thereof, show an embodiment of the present invention, and are used to explain the principle of the present invention together with the description.

It is typical structure explanatory drawing for demonstrating the structure of the experimental apparatus provided with the fryer function for demonstrating this invention. (A) is a typical block diagram for demonstrating the structural example of the sample electrode used for the experiment which concerns on this invention. (B) is a typical block diagram explaining the sample electrode which has the other structure used for experiment of this invention. It is a typical block diagram for demonstrating the detail of the structural example of the sample electrode used for the experiment which concerns on this invention.

  Prior to the description of the embodiments of the present invention, in order to deepen the understanding of the present invention, in the use of a food fryer, the effect of the electric field when a food is fried by forming a high electric field in edible oil will be described. .

  The edible oil is a vegetable oil, and the oil component differs in component and ratio depending on the oil type.

  In general, it is composed of unsaturated fatty acids such as linoleic acid, oleic acid and α-linolenic acid, and saturated fatty acids such as valmitic acid and stearic acid.

  As edible oils used for cooking such as tempura and fried food, canola oil and olive oil containing a large amount of oleic acid having only one double bond are preferable because they are difficult to be oxidized. More inexpensive corn oil, safflower oil, soybean oil, rice oil, etc. are used.

These inexpensive edible oils are rich in linoleic acid.
Linoleic acid is a divalent unsaturated fatty acid having two double bonds and is more easily oxidized than oleic acid.

  In the use of a food fryer, the cooking oil used is oxidized and deteriorated by the action of heat and air. The degree and progress of deterioration depends on the accumulation of frying time and frying temperature.

  When the oil is oxidized, a peroxide is generated, and the peroxide is decomposed to generate a low molecular decomposition product, while the peroxide is polymerized to generate a polymer.

  Furthermore, since the ingredients in the deep-fried food contain moisture, the moisture begins to soak into the frying oil during the frying operation, and heat is also added to the water to cause hydrolysis of the oily components, producing free fatty acids. .

The increase in polymer causes an increase in oil viscosity, and the increase in free fatty acids promotes oxidation.
When an aromatic compound is generated by heat, it also causes odor.

  In this way, since many of the substances produced by the deterioration of oil have polarity, they may be collectively referred to as polar compounds (polarized in the molecule) in the art.

  In the description of the present invention, unless otherwise specified, substances generated by oil degradation are collectively referred to as polar compounds.

  Deep fried tempura, cutlet, or fried food can be fried deliciously, and the garment will not soften or become sticky even after a long time since fried. In order to prevent this, the above-mentioned oxidation should be suppressed, the moisture of the ingredients should be left in the ingredients moderately, and the frying conditions should be devised so that the moisture that exudes into the oil from the food during the frying operation will immediately evaporate. There is a need to.

  In the present invention, a film of a low work function substance is provided on the electrode surface for forming a high electric field in the oil during the frying process, so that electrons are actively injected into the oil and the oil is oxidized. It suppresses.

  Hereinafter, the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a configuration explanatory diagram for explaining the configuration of an experimental apparatus having a flyer function for explaining the present invention.

  An experimental apparatus 100 shown in FIG. 1 has a basic configuration including a DC power source 101, a measurement oil tank unit 102, an ammeter 103, and a temperature controller 104.

  The DC power source 101 only needs to be able to apply a DC voltage of several kilovolts. In the experiment of this case described later, the DC power source 101 was used by applying 2 kV.

  The oil tank for measurement 102 includes an oil tank 105 and a mantle heater 106 provided so as to surround the oil tank 105 except for the upper side (in the drawing).

  The oil tank 105 is filled with a predetermined amount of various edible oils at the time of measurement, and the counter electrode 108, the sample electrode 109, and the K thermocouple 110 are immersed in the oil 107 by a predetermined part.

  Each of the counter electrode 108 and the sample electrode 109 can have a plate shape, a concave or convex plate shape, a rod shape, or the like as desired, but in the experiment described below, a flat plate shape is used and parallel facing Be placed.

  The counter electrode 108 may also serve as the oil tank 105 when a metal electrode is used for the oil tank 105.

  The ammeter 103 is an ammeter for assuming a minute current with high accuracy. In this experiment described later, an ammeter with a minimum reading of 100 μA was used.

  The DC power source 101 and the ammeter 103 are electrically connected by a wiring 114, and the ammeter 103 and the counter electrode are electrically connected by a wiring 113, respectively.

  The temperature controller 104 and the K thermocouple 110 are electrically connected by the wiring 111, and the temperature of the oil 107 measured by the K thermocouple 110 is the mantle heater 106 electrically connected to the temperature controller 104 by the wiring 112. The heating temperature is controlled to a predetermined temperature by the temperature controller 104.

An example of the configuration of the sample electrode is shown in FIGS.
Sample electrodes (200a, 200b) shown in FIGS. 2 (a) and 2 (b) have a first film (202a, 200b) on one surface of a rectangular electrode substrate (201a, 201b) having a surface area of a predetermined size. 202b) and the second film (203a, 203b) is provided on the other surface.
In the case of the example of FIG. 2A, both the first film 202a and the second film 203a are made of a low work function material and function as an electron emission layer.
In the example of FIG. 2B, the first film 202b is made of a low work function material, and the second film 203b is preferably made of an electrically insulating material.

  The low work function material used in the present invention is chemically non-reactive with edible oil for fried foods and insoluble in edible oil and water at 300 ° C. or lower. It is desirable that a material having a low work function of 3 eV or less is selected from materials that are stable at a temperature of 5 and that are safe for the human body.

Specifically preferred as the low work function material used in the present invention is barium (Ba), LaB ₆ , CeB ₆ , W—Cs, W—Ba, W—O—Cs, W—. O-Ba, 12CaO. 7Al ₂ O ₃ (C12A7) electride and the like can be mentioned.
In particular, N (nitrogen) -containing LaB ₆ is a preferred material.

  The second film 203b in the present invention is provided as necessary in order to prevent the electrode substrate 201b from coming into direct contact with oil.

  In the present invention, the material constituting the second film 203b is a material that is chemically resistant to the oil used and that maintains its properties even when heated to about 250 ° C. Therefore, it is desirable to select a material that is safe for humans.

  On the other hand, it is desirable that a preferable electrical insulating material employed for forming the second film 203b shown in FIG. 2B is appropriately selected from fluororesins as desired.

  In particular, PTFE (polytetrafluoroethylene), PFA (tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer), FEP (tetrafluoroethylene / hexafluoropropylene copolymer), ETFE (tetrafluoroethylene / ethylene copolymer) , PVDF (polyvinylidene fluoride), PCTFE (polychlorotrifluoroethylene), and ECTFE (chlorotrifluoroethylene-ethylene copolymer) are preferably selected according to the fryer and frying conditions to be applied.

In the example of FIG. 2, the first films 202a and 202b and the second film 203a are configured to be in direct contact with oil, but the surfaces of these films are heated for safety. It is also preferred to cover and protect the oil with a material that is chemically resistant and has little change over time in its resistance and is more human safe.
As such a material, the above-mentioned fluororesin is exemplified as a preferable one.

  When a protective film that covers the first films 202a and 202b and the second film 203a is provided with a fluororesin, electrons are emitted from the first films 202a and 202b and the second film 203a into the oil. In order to prevent this, it is desirable that the film thickness be controlled to a thickness that exhibits a tunnel effect and does not cause pinholes.

The electrode substrates 201a and 201b are made of a metal such as aluminum, nickel, copper, or iron, or an alloy such as brass, stainless steel, or tin alloy.
In addition, a heat-resistant conductive resin, or a composite in which a plating such as nickel, aluminum, silver, or gold is provided on the surface of the heat-resistant resin itself may be used.

  In the present invention, SUS316L is particularly preferably used for the electrode substrates 201a and 201b.

FIG. 3 shows one particularly suitable example of the sample electrode.
The sample electrode 300 includes an electrode substrate 301, a first film 302, and a second film 303.

  The first film 302 has the same function as the first films 202a and 202b, and is made of the same material as that of the first films 202a and 202b.

  The transition layer 304 is a material having a work function (Φ3) value that fills a numerical gap between the work function (Φ1) value of the electrode substrate 301 and the work function (Φ2) value of the first film 302. Composed.

When the electrode substrate 301 is made of SUS316L (Φ1 = 4.5 eV) and the first film 302 is made of LaB ₆ (Φ1 = 4.5 eV), in the example shown in FIG. Six layers are stacked from the electrode substrate 301 side in the descending order of the absolute value of the work function.

Specifically, in order from the electrode substrate 301 side, an Al (aluminum: 4.3 eV) layer 306, a Zr (zirconium: 4.1 eV) layer 307, an Hf (hafnium: 3.8 eV) layer 308, La (lanthanum: 3) 0.5 eV) layer 309, Er (erbium 3.2 eV) layer 310, and Ba (barium: 2.4 eV) layer 311 are laminated.
The layer 311 may be composed of Pr (praseodymium) and Sm (samarium) in addition to Ba.

The fluororesin may have different thermal stability depending on the type of the base substrate.
For example, in the case of PTFE, the one provided in SUS304 and SUS316, Al ₂ 0 ₃ (aluminum oxide) surfaces, but it begins to decompose at a temperature of 340-360 ° C. Atari, Ni (nickel) and NiF 2 (nickel fluoride) Those provided on the surface show thermal stability up to around 400 ° C.

  In the case of PFA, if it is a stainless steel surface such as SUS304 or SUS316, it loses thermal stability around 320 ° C, but if it is a Ni (nickel) or NiF2 (nickel fluoride) surface, it is thermally heated to around 395 ° C. Keep stability.

  In PTFE and PFA, the thermal stability equivalent to the Ni (nickel) or NiF2 (nickel fluoride) surface is maintained even on the Ni-P (nickel phosphorus) plating surface.

  In the case of FIG. 3, an example is shown in which an undercoat layer 305 of Ni—P (nickel phosphorus) plating is provided on the surface of an electrode substrate 301 made of SUS316L, and a second film 303 made of PTFE is provided on the surface. Has been.

  By providing the transition layer 304 as in the configuration of FIG. 3, the emission efficiency of electrons from the first film 302 can be increased.

  Also, by providing an undercoat layer 305 made of a material such as Ni (nickel), NiF2 (nickel fluoride), or Ni-P (nickel phosphorus), the thermal stability of the second film 303 made of a fluororesin is provided. Can be secured.

1. Preparation of Sample Electrode As an electrode substrate, two SUS316L substrates having 5 cm × 40 cm length and 1 mm thickness were prepared.
The two SUS316L substrates were cleaned by an ultra-clean cleaning method that is usually used in the semiconductor field.

One of the cleaned SUS316L substrates was set at a predetermined position of a sputtering apparatus obtained by modifying a part of a commercially available apparatus, and a LaB ₆ film was provided on one side of the substrate under the following conditions (sample electrode A).

And the other one SUS316L substrate was used as a comparative sample electrode X without providing the LaB ₆ film.

LaB ₆ film preparation conditions:
LaB ₆ was formed on the above electrode substrate using a rotating magnet type sputtering apparatus under the following conditions.
Ar gas flow rate 1000 sccm,
Pressure ... 50mTorr
Distance between LaB ₆ molding target and electrode substrate: 7 cm
Temperature of electrode substrate ... 300 ° C
Target applied power: 13.56 MHz RF power 2 W / cm ²
Film forming rate: 30 nm / min
Film thickness: 2μm

As an oil tank, a stainless steel frying pan having a diameter of 30 cm and a depth of 20 cm was prepared and set in a mantle heater of an experimental apparatus having the same configuration as the apparatus shown in FIG.
At this time, the stainless steel frying pan was electrically connected to the wiring 113 on the ammeter 103 side so as to be used as a counter electrode.

After preparing as described above, ingredients for tempura were prepared as follows.
Tempura preparation:
Soft flour ... 150g
5 tablespoons potato starch
Baking powder ... 1 and 1/2 teaspoon
All these powders were mixed to make tempura powder.
An appropriate amount of water was added to this tempura flour and mixed thoroughly, then placed in a refrigerator and kept cool (clothes).
As ingredients (tempura seed),
Long eggplant ... 12 sheets Lotus root ... 12 sheets Shiitake ... 12 sheets Large leaves ... 12 sheets Pumpkin ... 12 sheets 3 sheets of firewood ... 12 sheets were prepared.

Commercially available salad oil and sesame oil were prepared as fried oil.
Oil was poured into the pot at a ratio of 1 tablespoon of sesame oil to 200cc of salad oil until the middle of the pot.

During the frying operation, DD-2.5 kV was applied to the sample electrode A. The stainless steel oil tank was connected to the ground electrode.
Lightly dusted (large leaves on the back of the leaves, shiitake on the umbrella) Take the container with the clothes from the refrigerator and put a piece of ice in the above ingredients. Fried at the oil temperature.
The timing to take out the deep-fried tempura from the oil tank was the time when the sound of moisture evaporating from the beginning changed to a crackling and dry sound, and the bubbles with small oil surface became larger.

After having drained enough, after eating one check for deep-fried condition, the rest was left for a day.
I ate one of the abandoned ones, and the rest ate it after reheating it in the microwave.
The tempura was fried and sampled in the same manner as in the case of the sample electrode A except that the comparative sample electrode X was used instead of the sample electrode A.
The fried food was used in comparison with this case and 6 pieces each.
The texture evaluation is shown in Table 1 below.

1. Clothing making flour ... 100g
Material A
・ 1 egg ...
・ Cold water ... 150cc
After putting “Material A” in a bowl and mixing, further flour was added and lightly mixed with thick chopsticks (melted flour).

2. Preparation of fried food and frying work The prepared (seed) pork loin (150g) / 12 pieces were prepared with salt and pepper to prepare the taste.
These pork loins were dressed in the order of melted wheat flour → eggs → bread crumbs (fried food).
Immediately before attaching the garment, heating of the oil tank containing the same oil as in Example 1 was started.
First, fry over medium heat, and when it begins to fry, turn it to a high heat and finish it.
The timing for removing the fried cutlet from the oil was substantially the same as in Example 1.
As in Example 1, the tasting. At first, the sound of evaporation of moisture and moisture changes into a crackling and dry sound, and small bubbles become larger.
The tasting and comparative sample electrode A were performed in the same manner as in Example 1.
The fried food was used in comparison with this case and 6 pieces each.
The results are shown in Table 2 below.

DESCRIPTION OF SYMBOLS 100 ... Experimental apparatus 101 ... DC power supply 102 ... Measurement oil tank part 103 ... Ammeter 104 ... Temperature controller 105 ... Oil tank 106 ... Mantle heater 107 ... Oil 108 ..Counter electrode 109 ... sample electrode 110 ... K thermocouple 111, 112, 113, 114, 115 ... wiring 116 ... grounding electrode 117 ... negative electrode 200a, 200b ... sample electrode 201a, 201b, 301 ... electrode substrate 202a, 202b, 302 ... first film 203a, 203b, 303 ... second film 300 ... sample electrode 301 ... electrode substrate 304 ... Transition layer 305 ... Undercoat layer 306 ... Al layer 307 ... Zr layer 308 ... Hf layer 309 ... La layer
310 ... Er layer 311 ... Ba layer

Claims (3)

  An electrode structure for a food fryer that is used in a food fryer that heats cooking oil in an oil tank and fries the food in a predetermined temperature range, and has an electrode surface for applying a voltage to the cooking oil while frying the food. An electrode structure for a food fryer comprising a film of a material having a low work function on the electrode surface. The electrode structure according to claim 1 is embedded in oil poured into an oil tank of a food fryer, and a frying operation process is performed while applying a negative DC potential or an AC potential to the electrode structure. How to fry food.   An electrode structure for a food fryer comprising an electrode substrate and an electron emission film formed on at least one surface of the electrode substrate.

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