JP2008000048A - Carrier-system freezing method and device for meat - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a carrier-system freezing method for meat enabling production of high-quality frozen scallop eyes the surfaces after frozen and the cut surfaces of which are whitened and cause no crack in body: and to provide a carrier-system freezing device for meat also enabling production of high-quality frozen scallop eyes the surfaces after frozen and the cut surfaces of which are whitened and cause no crack in body. <P>SOLUTION: The carrier-system freezing device for meat has the following structure: a conveyor belt 15 conveying meat 20 into a cooling space 2 provided with a cold-air supply means is extended; the belt surface of the conveyor belt 15 is made of material having high heat conductivity; a nozzle 7 jetting or spraying cool air toward the under surface of the belt is mounted at the under surface side of the conveyor belt 15; a stirring means 10 is mounted at the cooling space above the belt, so that the amount of the cool air blown through the nozzle 7 and coming in contact with the belt under surface is larger than the amount of the cool air supplied to the top surface of the meat 20 placed on the conveyor belt 15. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a collision jet cooling technique in which meat such as scallops, fish fillets, and livestock meat is conveyed by a conveyor and continuously cooled by jetting cold air, and in particular, the meat can be frozen uniformly and high quality. The present invention relates to a meat transporting type freezing method and apparatus capable of producing a frozen product.

  As a generally used method for freezing meat, a brine type freezer using a liquid refrigerant (brine) described in Patent Document 1 (Japanese Patent Laid-Open No. 2003-322452) or the like, or Patent Document 2 (Japanese Patent Laid-Open No. 2004-169960). There is a collision jet type freezer described in the publication. The brine type freezer performs rapid freezing of food by spraying brine such as ethylene glycol and propylene glycol from above and below the object to be frozen, and enables relatively uniform freezing in a short time. However, some of the brines used in the brine type freezer have a harmful effect on the human body, and there is a problem that the management of the brine is complicated in order to prevent adhesion to food or leakage to the outside.

On the other hand, the impinging jet freezer is a method of freezing by injecting cooling air, and has the advantage that it is safe and easy to handle. The transport-type cooling device described in Patent Document 2 is placed on a conveyor belt by placing a slit nozzle directly above and below the conveyor belt so as to cool the food while it is placed on the conveyor and transported. The food is cooled by cold air that is ejected from the upper and lower slit nozzles. In this way, the food can be efficiently cooled in a short time by spraying the cold air from above and below the food. Patent Document 3 (Japanese Patent Laid-Open No. 2003-116505) also proposes a freezing device that supplies cold air only from above the article to be frozen.
However, in order to quickly freeze with a collision jet type freezer, it is necessary to increase the wind speed, and because extremely low temperature cold air is used, the frozen state of the meat may become uneven or cracked. It has been found that quality is degraded. As shown in FIG. 10 (b), in the frozen state by the brine type freezer, the unfrozen part or the freezing line exists in the upper part of the frozen product, whereas, as shown in (a), by the impinging jet type freezer. It exists at the bottom in the frozen state. As a result, there is a problem that cracking of the body is promoted.

  Here, as an example, freezing technology for scallop pillars will be described. Frozen scallops in general circulation are called ball-cooled and are widely used because they can be stored for a long time and various cooking methods can be applied after thawing. Technology. The production method of the ball cooling is to wash scallops from which raw shells, scales, etc. have been removed from raw scallops, and after removing and removing scallops that have collapsed and dead scallops from the scallops, they are washed again and drained. Later, it is quickly frozen in a freezer. Patent Document 4 (JP-A-3-254632) proposes a method for producing a frozen scallop clam. This is because the debris once cut off from the shell is washed and sterilized, then placed on the shell, instantly frozen with a refrigerant such as liquid nitrogen, and further, this stripped shell is glazed and then -30 ° C or lower. This is a method of complete freezing in a freezer for 4 hours or more. In this way, the freshness of the flesh can be maintained for a long time by instant freezing.

  Factors that determine the quality of such frozen scallops include quality factors such as color, cracking, and blooming (with frost). As shown in FIG. 11 (a), the high quality scallop frozen in a good frozen state is uniformly whitened on the surface and cut surface, and is not cracked. If the frozen state is bad, the surface becomes dark as shown in FIG. 11 (b), the surface is cracked as shown in (c), or the inside is not frozen as shown in (d). Part remains. When a scallop is rapidly frozen by a conventional impinging jet freezer, such an unfavorable scallop exists and it is difficult to obtain a uniform and good frozen state.

Japanese Patent Laid-Open No. 2003-322452 JP 2004-169960 A JP 2003-116505 A JP-A-3-254632

  Therefore, in view of the above-mentioned problems of the prior art, the present invention is capable of freezing meat evenly and efficiently, and transporting meat capable of producing high-quality frozen meat products, particularly frozen scallops that are free of cracks. An object of the present invention is to provide a freezing method and apparatus.

As a result of repeated freezing experiments on meat such as scallops, tuna, and livestock meat, the present invention relates to the cooling ratio of the upper and lower surfaces of the meat as a cause of cracking, and the color of the frozen product is related to the air volume of the lower surface of the meat. It was found that the cooling temperature is related.
Therefore, in order to solve the above-described problems, the present invention has a conveyor belt extending in the cooling space, and transporting the meat placed on the conveyor belt, while the meat is fed by the cold air supplied into the cooling space. In the freezing method for transporting frozen meat,
The cold air is brought into contact with the lower surface of the belt from the nozzle provided on the lower surface side of the conveyor belt, and the cold air supplied to the cooling space above the belt is stirred by the stirring means,
The amount of cool air to be brought into contact with the lower surface of the belt is set larger than the amount of cool air supplied to the upper surface of the belt.

  According to the present invention, within the range of input energy equivalent to that of a conventional impingement jet freezer, the surface color, the position of the slow freezing part, the surface It is possible to control factors related to commercial value such as cracks and surface frost. In addition, compared with the known brine type freezer, the conventional impinging jet type freezer was inferior in refrigeration capacity, but by adopting the configuration of the present invention, it can have the same level of capacity as the brine type freezer. The quality of the product can be improved. In addition, since the impact jet type freezer can obtain the same quality as the conventional brine type freezer, it is possible to give superiority in terms of the environment and the cleaning surface compared to the brine type freezer.

The cooling air is supplied so that the temperature in the cooling space is −38 ° C. or lower.
Further, the air volume balance of the cold air is characterized in that the belt lower surface side: belt upper surface side is 9: 1 to 7: 3.
Furthermore, the meat is scallops.

In addition, as an invention of the apparatus, a conveyor belt that conveys meat is extended in a cooling space provided with cold air supply means, and the conveyor belt is formed of a material having a high heat transfer rate,
The lower surface of the conveyor belt is provided with a nozzle for bringing cold air into contact with the lower surface of the belt, and the cooling space above the belt is provided with stirring means for stirring the supplied cold air.
The amount of cool air to be brought into contact with the lower surface of the belt is set larger than the amount of cool air supplied to the upper surface of the belt.
Further, the cold air supply means supplies cold air so that the temperature in the cooling space is −38 ° C. or lower.

Further, the cold air supply means sets the air volume balance of the cold air so that the belt lower surface side: belt upper surface side is 9: 1 to 7: 3.
Further, the cold air supply means includes a feed duct that feeds the cold air generated by the cold air generator to the nozzle, and a return duct that circulates the cold air contacted from the nozzle to the cold air generator,
A bypass passage is provided on a side surface of the feed duct, and a structure in which cold air having a predetermined air volume flows into the space above the belt from the bypass passage is provided.
Furthermore, the meat is scallops.

As described above, according to the present invention, meat can be frozen uniformly and efficiently, the color of the meat after freezing is good, and cracking can be prevented, and a high-quality frozen meat product, particularly a frozen scallop. It is possible to provide a method and apparatus for transporting meat that can produce scallops.
In addition, the impact jet type freezer is used, so it is highly safe and easy to handle, and has the same refrigerating capacity as the conventional brine type freezer with the same or less input energy as the conventional brine type freezer. Obtainable.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, but are merely illustrative examples. Not too much.
1 is a side view of a transport type freezing apparatus according to an embodiment of the present invention, FIG. 2 is a plan view of the transport type freezing apparatus of FIG. 1, and FIG. 3 is a cross-sectional view of the transport type freezing apparatus of FIG. It is.
In the present embodiment, scallops will be described as an example of freezing. However, the present invention can be applied to seafood such as fish fillets and crab meat and livestock such as beef and pork internal organs.

As shown in FIGS. 1 to 3, in the transport type freezing apparatus 1 of the present embodiment, a conveyor belt 15 that transports scallops 20 is extended in a casing 2 that forms a cooling space. The conveyor belt 15 is formed of a material having a high heat transfer rate, and for example, a steel belt is preferably used. The scallop 20 is placed on the conveyor belt 15 and rapidly frozen when passing through the freezing apparatus 1 and is discharged from the freezing apparatus 1 as a frozen scallop 20 '. For example, scallops having a central temperature of about 10 ° C. are supplied on the inlet side of the freezing device 1, and are frozen to about −20 ° C. and discharged on the outlet side of the freezing device 1.
A cold air generator 3 is provided at the upper part of the casing 2, and a feed duct 4 extends from the cold air generator 3 downward. A fan 5 is installed in the feed duct 4 to send the cool air generated by the cool air generator 3 downward.

An end of the feed duct 4 is connected to a lower cooling space 6 installed below the conveyor belt 15. The lower cooling space 6 is provided with a slit nozzle 7 for vertically ejecting cold air toward the lower surface of the conveyor belt 15. A plurality of the slit nozzles 7 are arranged at predetermined intervals in the transport direction of the transport conveyor 15.
An agitator fan 10 is installed above the conveyor belt 15 to agitate the upper cooling space 11 of the conveyor belt 15.
In addition, a return duct 13 is disposed on the side of the casing 2, and cool air blown to the conveyor belt 15 from the upper cooling space 11 and / or the slit nozzle 7 of the conveyor belt 15 is circulated to the cold air generator 3. It is supposed to let you.

The scallop pillar 20 conveyed by the conveyor belt 15 is cooled and collided (contacted) with the slit nozzle 7 on the lower surface of the conveyor belt 15 to cool the belt 15, and the lower surface of the scallop pillar 20 is rapidly cooled by the heat transfer. On the other hand, the upper cooling space 11 is agitated by the agitator fan 10, and cool air is supplied to the upper surface of the scallop pillar 20 to cool the entire scallop pillar.
Further, in this embodiment, the air volume supplied to the lower surface side of the conveyor belt 15 is set to be larger than the air volume supplied to the upper surface side.
At this time, the air volume balance of the cold air supplied to each is preferably 9: 1 to 7: 3 on the belt lower surface side: belt upper surface side, and more preferably about 9: 1 on the belt lower surface side: belt upper surface side. And
Moreover, it is preferable that the temperature in the casing 2 is −38 ° C. or lower. Thereby, uniform and good freezing is possible, and it is possible to produce a high-quality frozen scallop that is white and does not break.

Further, as shown in FIG. 3, a bypass passage that leads to the upper cooling space 11 of the conveyor belt 15, that is, the upper cooling space 11 may be provided as the air volume adjusting means. This can be achieved, for example, by forming a feed duct wall facing the upper cooling space 11 with a material having a hole such as a punching metal 14.
Thereby, since a part of cold wind branches through the punching metal 14 and flows into the upper cooling space 11, the air volume on the upper surface of the scallop pillar can be secured.

In order to verify the freezing ability in the transport-type freezing apparatus 1 having the above-described configuration, a verification experiment using a test machine was performed. 4 is a table showing the condition factors of each test piece, FIG. 5 is a table showing measured values of RGB with respect to the condition factors of each test piece, FIG. 6 is a table showing the contribution ratio of the condition factors to RGB, and FIG. 8 is a graph showing the position of the freezing line from the lower surface of the test piece, FIG. 8 is a diagram showing the surface color state of the frozen scallop column with respect to the lower wind speed and the cold air temperature, and FIG. 9 is the surface color of the frozen scallop column with respect to the upper wind speed and the cold air temperature. It is a figure which shows the state of.
Evaluation items for frozen scallops include surface color, body cracking, slow freezing, and flower bloom (with frost). In this experiment, the surface color and body cracking are verified.
Although cracks were confirmed visually, the surface color is evaluated by an evaluation method using a color difference meter, which will be described later, because it is difficult to make a quantitative determination visually.

First, in the surface color, the effect of each condition factor such as the internal temperature, the upper wind speed, the lower wind speed, and the total air volume on the surface color was verified.
The method of measuring the surface color is to measure the surface color of frozen scallops using a color difference meter, digitize it as color difference meter data such as L * a * b, XYZ, etc., and convert this color difference meter data to the RGB color system This makes it possible to quantitatively evaluate the surface color with an expression color close to that seen with the naked eye. Although the surface color was digitized using a Munsell color sample, it was difficult to make a precise determination. Therefore, a measurement method using such a color difference meter was used.
In this surface color evaluation method, in the case of slow freezing, transparent ice is formed on the surface, so when measuring with a color difference meter, the light for measurement emitted from the color difference meter is absorbed or scattered in the ice layer, and the actual color It is measured as a darker color than the data. On the other hand, in the case of rapid cooling, since the ice crystals on the surface are small, the measurement light is reflected and detected as a white color. Therefore, it can be used as an effective objective evaluation because it can be an indicator of the quality of a frozen product, in particular, whether quick freezing is good or bad.

The test piece was a raw scallop and a dummy with a konjac cut into a cylinder like a shell as a test piece for confirming the tendency of the unfrozen position. Nine raw scallops and dummies are arranged in parallel on the tester, and the tester's operating conditions are “condition in the chamber”, “upper wind speed”, “lower wind speed”, “air volume ≒ belt speed” according to the L9 assignment in the experimental design method. The experiment was conducted. FIG. 4 is a table assigned to condition factors and levels in accordance with the experimental design method.
For the experimental evaluation of the surface color, the surface color of the frozen scallop column is digitized using a color difference meter (Lab color method), and the obtained a * b * L * value is converted into the RGB color system value. After conversion, the contribution ratio to the parameters “R”, “G” and “B” and the values of “internal temperature”, “upper wind speed”, “lower wind speed”, “belt speed≈air volume” were obtained.
As a result, the table shown in FIG. 5 was obtained. In addition, although it is desirable that the level of each condition factor is shaken at equal intervals, in this experiment, measurement was performed using approximate values because of the configuration of the tester. From the experimental results of FIG. 5, the contribution ratio of each factor of FIG. 6 was obtained. According to this, it was confirmed that the upper wind speed, the lower wind speed, and the internal temperature contributed to the improvement in the color (whiteness) of the frozen scallops. Therefore, it can be seen that by adjusting the upper wind speed, the lower wind speed, and the internal temperature, it is possible to manufacture a frozen scallop having a white surface color and a good frozen state.

As for the experimental evaluation of cracks, when observing a frozen scallop with cracks, the upper part of the scallop (on the side opposite the belt contact surface) was opened. I know that there is.
Since the scallop muscle fibers have a direction in the vertical direction, when rapidly freezing from the surroundings, the scallop muscle fibers will open unless the freezing and expansion force is released.
When carrying type freezing by a belt conveyor as in this embodiment, scallops are aligned on the upper surface of the belt and muscle fibers are arranged in the vertical direction. Since the freezing also proceeds from the lower surface of the belt, when the freezing is performed rapidly from the upper surface, the upper part of the scallop is opened without releasing the freezing expansion force on the lower surface. As shown to Fig.10 (a), when frozen using a collision jet-type freezer, an unfrozen part or a freezing line is located below. This means that freezing on the upper side is fast. As a result, the freezing and expanding force cannot be released upward, and the freezing and expanding force cannot be released to the side in contact with the belt.

For this reason, it is necessary to supply a freezing force that does not cause cracks on the upper surface of the scallop column, and the freezing force = "inside temperature""upwindspeed""downwindspeed""belt speed ≒ air volume" It was necessary to have a method of rapidly releasing freezing and expansion to the upper surface by parameters, and this tendency was obtained.
As a result, the graph shown in FIG. 7 was obtained. As shown in the test piece 9, when the lower surface freezing was promoted, it was confirmed that the freezing expansion progressed to the upper surface by extremely loosening the upper surface freezing.

8 and 9 show the results of further freezing tests based on the above-described experimental evaluation of surface color and cracking. In addition, after RGB conversion of the color difference meter data, it has been found that the scallop shell that has been uniformly whitened in a good frozen state expresses the RGB value brightly, so the RGB value (230, 205, 185) of the scallop that appears whitest ), And the total RGB value 620 is the target value of the surface color.
As a result, the tendency of “color and crack” with respect to the freezing method of the upper and lower surfaces is summarized as follows.

From the above experimental evaluation, it can be seen that the lower surface side wind speed affects the color of the lower surface of the frozen product, and the upper surface side wind speed affects the color and cracks of the upper surface. In addition, when the temperature curve and the color of the ball cooling are associated with each other, when the time passing through the ball cooling submarine is early, it tends to be bright ≈ white.
Therefore, the freezing method finished in white without cracking is cold air temperature -38 ° C or lower, bottom surface freezing air speed 20m / s impinging jet type), top surface freezing air speed 5m / s (stirring method), freezing time 12 minutes / shell weight It has been found that conditions of 20-30 g are preferred. Therefore, as in this embodiment, by making the air volume of the cold air on the lower surface side of the belt larger than that on the upper surface side, and preferably keeping the temperature in the casing 2 at −38 ° C. or lower, the surface color is good and there is no crack. It has become clear that high quality frozen products can be produced.

  Thus, according to the present embodiment, compared to the conventional collision jet type belt freezer, the input energy is equal or less, and by changing the distribution of the upper air volume and the lower air volume, there is no cracking, It becomes possible to form a frozen state with a good surface color, and a high-quality frozen meat product can be produced.

It is a side view of the conveyance type freezing apparatus which concerns on the Example of this invention. It is a top view of the conveyance type freezing apparatus of FIG. It is XX sectional drawing of the conveyance type freezing apparatus of FIG. It is a table | surface which shows the conditional factor in each test piece. It is a table | surface which shows the measured value of RGB with respect to the conditional factor of each test piece. It is a table | surface which shows the contribution rate to RGB of a conditional factor. It is a graph showing the position of the freezing line from the lower surface of each test piece. It is a figure which shows the state of the surface color of the frozen scallop pillar with respect to a lower wind speed and cold air temperature. It is a figure which shows the state of the surface color of the frozen scallop pillar with respect to an upwind speed and cold wind temperature. The position of an unfrozen part or a freezing line is shown, respectively, (a) shows a frozen state by a conventional impingement jet freezer, and (b) shows a frozen state by a conventional brine type freezer. A photograph of frozen scallops is shown, (a) is in a good freezing state, (b) is in a surface color, (c) is in a cracked state, (d) is in an unfrozen part inside Represents the state to perform.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Conveyance freezing apparatus 2 Casing 3 Cold wind production | generation part 4 Feeding duct 5 Fan 6 Lower cooling space 7 Slit nozzle 10 Agitator fan 11 Upper cooling space 14 Punching metal 15 Conveyor belt 20 Scallop pillar

Claims (9)

A conveyor belt freezing method in which a conveyor belt is extended in the cooling space and the meat is frozen by the cold air supplied into the cooling space while transporting the meat placed on the conveyor belt.
Cold air is sprayed or dispersed (hereinafter referred to as contact) from the nozzle provided on the lower surface side of the conveyor belt, and the cold air supplied to the cooling space above the belt is stirred by a stirring means,
A method for freezing meat transport, characterized in that the amount of cold air to be brought into contact with the lower surface of the belt is larger than the amount of cold air supplied to the upper surface of the belt.   The method of claim 1, wherein cold air is supplied so that the temperature in the cooling space is -38 ° C or lower.   2. The meat transport freezing method according to claim 1, wherein the cold air volume balance is 9: 1 to 7: 3 on the belt lower surface side: belt upper surface side.   The method for freezing meat according to any one of claims 1 to 4, wherein the meat is a scallop. A conveyor belt that conveys meat is extended in a cooling space provided with cold air supply means, and the conveyor belt is formed of a material having a high heat transfer coefficient,
The lower surface of the conveyor belt is provided with a nozzle for bringing cold air into contact with the lower surface of the belt, and the cooling space above the belt is provided with stirring means for stirring the supplied cold air.
A meat freezing apparatus characterized in that the amount of cold air brought into contact with the belt lower surface is larger than the amount of cold air supplied to the belt upper surface.   6. The meat transporting type freezing apparatus according to claim 5, wherein the cold air supply means supplies cold air so that the temperature in the cooling space is −38 ° C. or lower.   6. The meat conveying type freezing apparatus according to claim 5, wherein the cold air supply means sets the air volume balance of the cold air so that the belt lower surface side: belt upper surface side is 9: 1 to 7: 3. The cold air supply means includes a feed duct that feeds the cold air generated by the cold air generator to the nozzle, and a return duct that circulates the cold air contacted from the nozzle to the cold air generator,
6. The meat conveying type freezing apparatus according to claim 5, wherein a bypass passage is provided on a side surface of the feed duct, and a cold air having a predetermined airflow flows into the space above the belt from the bypass passage. The meat freezing apparatus according to any one of claims 5 to 8, wherein the meat is a scallop.

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