JPH0566083B2 - - Google Patents

Description

[Detailed description of the invention]

TECHNICAL FIELD The present invention relates to a method for producing frozen sea urchin that enables long-term storage by freezing raw sea urchin. "Prior art and its problems" Traditionally, raw sea urchins made from the gonads of sea urchins have been eaten as sushi seeds, sashimi, etc., and are relatively expensive foods. Raw sea urchin loses its freshness quickly during transportation and storage, so freshness is of paramount importance in order to obtain a good taste. For this reason, as soon as raw sea urchins are harvested, they must be put through the distribution process and put on the market, making it difficult to maintain a constant amount of market circulation, making the product subject to rapid price fluctuations. In addition, one of the reasons why it is expensive is that it is difficult to preserve. Therefore, attempts have been made to freeze and preserve raw sea urchins, but when raw sea urchins are frozen using the normal quick-freezing method, the sea urchins become shriveled and look like they have melted when thawed, which reduces the commercial value of the sea urchins. Usually, most of it disappeared. In raw sea urchins, the eggs inside the gonads are attached to the mucus tube.
Furthermore, it is wrapped in an outer thin membrane to form a single reproductive form. The water content in the gonad is 60.5 for eggs.
%, and the surrounding mucus is about 81%.
Moreover, the thickness of the egg membrane is about 0.002 to 0.005 μm.
In this way, when items with different moisture contents are frozen using the normal quick freezing method, the tissue destruction due to ice crystals becomes significant, and the original shape cannot be maintained when thawed. JP-A-62-14740 proposes a method in which raw sea urchin is treated with a moisturizing chemical solution and an ammonium alum solution and then frozen. However, in this method, the raw sea urchin is immersed in a chemical solution having a moisturizing effect such as sugars, which has a negative effect on the taste and tends to reduce the original flavor of the raw sea urchin. ``Object of the Invention'' An object of the present invention is to provide a method for producing frozen sea urchin that does not cause the sea urchin to crumble during thawing and that does not impair the original flavor of raw sea urchin. "Structure of the Invention" As a result of intensive research to achieve the above object, the present inventors have found that by treating raw sea urchins with microwaves for a very short period of time and then freezing them, the sea urchins can be effectively prevented from deforming during thawing. They have discovered that this can be prevented and have completed the present invention. That is, the method for producing frozen sea urchin according to the present invention is characterized in that raw sea urchin is treated with microwaves until its surface temperature reaches 30 to 50°C and internal protein denaturation does not occur, and then rapidly frozen. . According to the present invention, it is possible to prevent the product from crumbling during thawing, and to provide a product with high commercial value even when stored frozen. Furthermore, since there is no need to use special chemicals for processing before freezing, the original flavor of raw sea urchin can be retained. The reason why the method of the present invention prevents the body from collapsing during thawing is not clear, but it is speculated that it is as follows. In other words, when raw sea urchin is treated with microwaves for a very short period of time, the water on the surface (free water) evaporates, and the gelatinous mucus contained in the water turns into a gel, resulting in particles with a thickness of about 0.007 to 9 μm. A thin film is formed that wraps around the gonads of raw sea urchins and is thought to prevent them from disintegrating during thawing. The microwave treatment must be carried out to an extent that does not cause protein denaturation within the raw sea urchin.
This is because if the protein is denatured to the inside, the flavor as a fresh food will be lost. For this reason, the present invention provides that the microwave treatment is
Do this so that the surface temperature of the raw sea urchin is 30-50℃. When the surface temperature exceeds 50°C, flavor deterioration is likely to occur due to internal protein denaturation, and when the surface temperature is below 30°C, the effects of the present invention cannot be sufficiently obtained. The microwave processing time varies depending on the output of the microwave heating device and the amount of raw sea urchin to be processed, but for example,
When processing 50 to 60 cases containing 150 g of raw sea urchin using a device with a frequency of 2450 MHz, rated high-frequency output of 1500 W, and rated power consumption of 1 kW x 3, approximately 6 to
A treatment time of about 15 seconds was appropriate. According to a further preferred embodiment of the present invention, the microwave treatment is carried out while blowing gas at -20°C or lower onto the raw sea urchin. In this way, by blowing cold gas onto raw sea urchin and treating it with microwaves, the moisture on the surface evaporates more quickly while preventing internal protein denaturation caused by heating.
Film formation by gelatinous mucilage can be promoted. In this case, the gas below -20℃ is
Gasified liquefied nitrogen gas, liquefied carbon dioxide, or the like may be used, or air cooled by an air blast refrigerator or the like may be used. Further, the rapid freezing after the microwave treatment is preferably carried out at -20°C or lower, and more preferably at -40°C or lower. Therefore, although a normal air blast refrigerator or the like may be used, it is more preferable to freeze by blowing liquefied nitrogen gas, liquefied carbon dioxide gas, or the like. The product after rapid freezing may be stored in a normal freezer, preferably at -10°C or lower, more preferably at -20°C or lower. This allows storage for several months to over a year. If you take out this raw sea urchin and thaw it, 5 to 10
It is sufficient to thaw the sea urchin at ℃, thereby restoring the raw sea urchin that maintains the same freshness as freshly harvested raw sea urchin. In this case, there is very little loss of body parts during thawing, and the product value does not decrease.
Also, the flavor is well maintained. "Embodiment of the Invention" The figure shows an example of a microwave processing apparatus used to implement the present invention. This microwave processing apparatus 11 has a processing chamber 12, and a belt conveyor 13 passing through the processing chamber 12 is installed. Belt conveyor 1
3 carries a case 14 containing raw sea urchin,
It passes through the processing chamber 12 continuously at a predetermined speed. Three microwave heating devices 15 are installed in the processing chamber 12, and the raw sea urchin placed in the case 14 is irradiated with microwaves by these devices.
Further, the processing chamber 12 is connected with an introduction pipe 16 for low-temperature nitrogen gas taken out from a liquefied nitrogen cylinder, and is also provided with an exhaust pipe 17 for the nitrogen gas. Using this apparatus, raw sea urchin was subjected to microwave treatment under the following conditions. As the microwave heating device 15, one with a frequency of 2450 MHz, a rated high-frequency output of 1500 W, and a rated power consumption of 1 kW x 3 units was used. Belt conveyor 1
Speed of 3 is 1.6 to 4m/m (variable type)
And so. The size of case 14 is D90mm x W180
mm×H20mm, and there are 150 raw sea urchins in the case 14.
I put in each g. Then, from the introduction pipe 16 -30 to -
A low-temperature nitrogen gas of 40° C. was introduced into the processing chamber 12 and, after flowing through the processing chamber 12, was exhausted from the exhaust pipe 17. Under the above conditions, the raw sea urchins placed in the case 14 are placed on the belt conveyor 13 and continuously transported to the processing chamber 1.
2, and was irradiated with microwaves using a microwave heating device 15. The processing time using the microwave heating device 15 is 6 to 15 seconds. Through this treatment, the surface temperature of raw sea urchin can be reduced to 30~30
The temperature was around 50℃. After performing microwave treatment in this way,
Raw sea urchins were rapidly frozen by blowing liquefied nitrogen gas at -60°C. The frozen sea urchin obtained in this way was heated to −20°C.
The samples were stored in a freezer for 3 months, and then taken out and allowed to thaw naturally before being subjected to a sensory test. In other words, thawed raw sea urchin was stored in a refrigerator at 5°C, taken out after 1, 2, and 3 days, and sampled by 45 panelists. They were asked to evaluate the items. The evaluation was as follows: +3...very good, +2...good, +1...slightly good, 0...slightly bad, -1...poor, -2...quite bad, -3...very bad, and the average of each panelist was taken. For comparison, raw sea urchins were directly blown with liquefied nitrogen gas at -60°C to freeze them, stored at -20°C for 3 months in the same manner as in the above example, and then taken out and allowed to thaw naturally. A sensory test similar to the above was conducted using sea urchin (raw sea urchin obtained by normal freezing) and raw sea urchin that had just been collected without being frozen at all (raw sea urchin that had not been frozen). The results are shown in the table below. As is clear from the table, raw sea urchin frozen and thawed using the method of the present invention maintains comparable quality compared to raw sea urchin that is not frozen, whereas raw sea urchin frozen using the normal quick freezing method maintains a quality comparable to raw sea urchin that is not frozen. The thawed raw sea urchin is
It can be seen that the quality is inferior even after thawing.

【table】

[Table] Note that the above example is an example in which microwave processing was performed while blowing low-temperature nitrogen gas, but in the apparatus shown in the figure, only microwave processing was performed without flowing low-temperature nitrogen gas, and then the above-mentioned It was confirmed that even with frozen sea urchin frozen in the same manner as in the example, the thawed product maintained good quality. "Effects of the Invention" As explained above, according to the present invention, raw sea urchin is treated with microwaves until the surface temperature reaches 30 to 50°C and internal protein denaturation does not occur.
Since the sea urchin is rapidly frozen, it is possible to prevent the sea urchin from deforming during thawing, and to restore raw sea urchin having good quality and no deterioration in flavor. Therefore, raw sea urchin can be stored for a long period of time, and the market price can be stabilized.

[Brief explanation of the drawing]

The figure is a schematic diagram showing an example of an apparatus for carrying out the present invention. In the figure, 11 is a microwave processing device, 12
13 is a processing chamber, 13 is a belt conveyor, 14 is a case, 15 is a microwave heating device, 16 is a low temperature nitrogen gas introduction pipe, and 17 is a discharge pipe.

Claims (1)

[Scope of Claims] 1. A method for producing frozen sea urchin, which comprises treating raw sea urchin with microwaves until its surface temperature reaches 30 to 50°C and does not cause internal protein denaturation, and then rapidly freezing the sea urchin. . 2. The method for producing frozen sea urchin according to claim 1, wherein the microwave treatment is performed while blowing a gas at -20°C or lower onto the raw sea urchin. 3. The method for producing frozen sea urchin according to claim 1 or 2, wherein the rapid freezing is carried out at -20°C or lower.