Storage methods for processed seafood products
Vacuum packaging and slow freezing with boiling thawing of seafood products address the equipment and thawing challenges, maintaining quality and flavor comparable to refrigerated storage.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- WAKAMATSUYA CO LTD
- Filing Date
- 2022-05-20
- Publication Date
- 2026-07-24
AI Technical Summary
Existing methods for preserving fishery paste products like kamaboko require costly equipment and specialized thawing procedures to maintain texture and flavor, leading to quality deterioration during freezing and thawing.
A method involving vacuum packaging, slow freezing, and boiling thawing of processed seafood products within their packaging to preserve texture and flavor without special equipment, with a preferred thawing time of 10 to 40 minutes, especially 20 to 30 minutes.
This method achieves a texture and flavor similar to refrigerated storage by minimizing ice crystal damage and improving quality, reducing costs and equipment needs.
Smart Images
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Abstract
Description
Technical Field
[0004] ,
[0006]
[0001] The present invention relates to a method for preserving fishery paste products such as kamaboko and hanpen by freezing them and then thawing them.
Background Art
[0002] When attempting to store and distribute fishery paste products such as kamaboko for a long time, freezing is preferred over refrigeration due to the expiration date. However, as in the case of general foods, serious quality deterioration (freezing damage) also occurs in kamaboko during freezing.
[0003] Therefore, for example, as a method for preserving fishery paste products such as kamaboko without impairing their composition and flavor, Japanese Patent Publication No. 46-6385 (Patent Document 1) discloses a method for storing fishery paste products without deterioration for a long time, in which the paste products are rapidly frozen directly or through their packaging films with liquid nitrogen to prevent crystallization of ice generated inside the products, and then stored in a refrigerator at -20°C.
Prior Art Documents
Patent Documents
[0004]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0005] However, the technique disclosed in Patent Document 1 has a problem in that it requires a large amount of cost for introducing and maintaining the equipment because liquid nitrogen is used. Furthermore, even when fishery paste products are frozen by the above method, appropriate procedures must be followed for thawing in order to thaw them without impairing their flavor, and there are problems in freezing and thawing for long-term storage and distribution of fishery paste products.
[0006] The present invention has been made in view of the above points, and aims to provide a method for preserving processed seafood products by modifying the thawing process when freezing the processed seafood products, thereby enabling preservation in a frozen state without the use of special equipment, while achieving a texture and flavor similar to that of refrigerated storage. [Means for solving the problem]
[0007] The present invention provides a method for preserving processed seafood products. The vacuum packaging process involves vacuum packaging processed seafood products in packaging bags, A freezing process for freezing the aforementioned processed seafood product, A thawing process in which the frozen processed seafood product is boiled and thawed while still in its vacuum packaging, It is characterized by including.
[0008] A preferred example of the method for preserving processed seafood products of the present invention is: The aforementioned freezing is slow freezing.
[0009] According to these methods for preserving processed seafood products of the present invention, processed seafood products can be frozen and stored without the need for special equipment, and then thawed and consumed.
[0010] A preferred example of the method for preserving processed seafood products of the present invention is: The duration of the thawing process is between 10 minutes and 40 minutes.
[0011] A preferred example of the method for preserving processed seafood products of the present invention is: The duration of the thawing process is 20 minutes or more and 30 minutes or less.
[0012] According to the present invention's method for preserving processed seafood products, by setting the thawing time within an appropriate range, the texture and flavor after thawing can be made closer to those of products stored under refrigeration. [Effects of the Invention]
[0013] As described above, according to the method for preserving fishery paste products of the present invention, it is possible to achieve a texture and flavor similar to those during refrigerated storage while preserving the products in a frozen state without using a special device.
Brief Description of the Drawings
[0014] [Figure 1] It is a flowchart for explaining a method for preserving fishery paste products according to an embodiment of the present invention. [Figure 2] It is a diagram for explaining a cross-section of slowly frozen kamaboko. [Figure 3] It is a diagram for explaining a cross-section of thawed kamaboko. [Figure 4] It is a diagram for explaining the drip rate when thawing kamaboko. [Figure 5] It is a diagram for explaining the breaking strength and breaking distance of kamaboko. [Figure 6] It is a diagram for explaining a cross-section of kamaboko thawed by boiling at different times. [Figure 7] It is a diagram for explaining the breaking strength of kamaboko thawed by boiling at different times. [Figure 8] It is a diagram for explaining the breaking distance of kamaboko thawed by boiling at different times. [Figure 9] It is a diagram for explaining the results of sensory evaluation of kamaboko thawed by boiling at different times.
Embodiments for Carrying Out the Invention
[0015] Hereinafter, embodiments of the method for preserving fishery paste products according to the present invention will be described in detail with reference to the accompanying drawings. Examples of fishery paste products include kamaboko, hanpen, fried kamaboko, chikuwa, tsukemono, crab kamaboko, etc., and kamaboko products that particularly require a texture such as elasticity and a bite are preferred.
[0016] As shown in FIG. 1, the method for preserving fishery paste products of the present embodiment includes a vacuum packaging step, a freezing step, and a thawing step.
[0017] The vacuum packaging process involves placing processed seafood products into packaging bags and then using a vacuum pump to remove the air from the bags. The packaging bags are typically made of materials such as polyethylene or nylon, which are substantially impermeable to liquids and gases. The processed seafood products are then vacuum-packed in these bags using a known vacuum packaging machine.
[0018] The freezing process is the process of freezing processed seafood products. This includes rapid freezing, but here we will mainly explain using slow freezing. Rapid freezing is a method in which, as the food's temperature decreases, it passes through the maximum ice crystal formation temperature range, which is between -1°C (where water begins to freeze) and -5°C (where almost all water freezes), within 30 minutes. Slow freezing, on the other hand, means normal freezing, not rapid freezing. In other words, slow freezing refers to a freezing method in which, when freezing kamaboko (fish cake), the time it takes to pass through the maximum ice crystal formation temperature range exceeds 30 minutes. From here on, unless otherwise specified, "freezing" will refer to slow freezing.
[0019] The thawing process involves boiling the frozen processed seafood product while it is still in its vacuum packaging. In this embodiment, the frozen processed seafood product is thawed by placing it in boiling water. The thawing time is preferably 10 to 40 minutes, and more preferably 20 to 30 minutes.
[0020] Next, we will explain the experimental details that support the effectiveness of the preservation method for processed seafood products according to this embodiment. Here, as an example of processed seafood products, we used kamaboko (fish cake on a board) (hereinafter referred to simply as "kamaboko" unless otherwise specified) for the experiment.
[0021] First, I will explain the experiment conducted to verify the quality deterioration caused by slow freezing during the freezing process. In this experiment, kamaboko (3% starch content by weight, 6 cm in diameter x 12 cm in length) was frozen in a freezer at -20 to -80°C for 3 days, 1 week, and 2 weeks, respectively, and the frozen cross-section was observed.
[0022] For the observation of frozen cross-sections, kamaboko (fish cake) with a board attached was frozen in a plastic storage bag that could be sealed with a zipper (hereinafter sometimes simply referred to as "storage bag"), removed from the freezer, and cut into pieces using a chisel and hammer as samples. These cross-sections were then photographed. Here, the kamaboko was photographed using a stereomicroscope with a digital camera (Shimadzu Rika Co., Ltd. STZ-161-TLED-HZ) with the settings of contrast 60 and gain 45.
[0023] Figures 2(A) to 2(C) are cross-sectional photographs of kamaboko (fish cake) frozen for one week. Figure 2(A) was frozen at -20°C, Figure 2(B) at -40°C, and Figure 2(C) at -80°C. As can be seen, the kamaboko frozen at -20°C (Figure 2(A)) has the largest ice crystals. These ice crystals decrease in size from the center outwards, with the largest ice crystal in the center measuring approximately 4 mm. In the -40°C sample (Figure 2(B)), the ice crystals are smaller, and in the -80°C sample (Figure 2(C)), the number of visible ice crystals is also reduced. Since no significant differences were observed in the frozen cross-sections of the samples frozen for 3 days, 1 week, and 2 weeks, photographs of the 3-day and 2-week samples are omitted.
[0024] Next, we will describe an experiment comparing kamaboko (fish cake) that was vacuum-packed and frozen at -20°C for one week, then naturally thawed in a household refrigerator for one day, with kamaboko that was thawed by boiling as described above. For boiling, approximately 20 liters of water were placed in a 40 cm diameter pot and brought to a boil. The frozen kamaboko, still in its vacuum packaging, was then placed into the boiling water (the same procedure was followed for subsequent boiling thawing experiments). The boiling time was 20 minutes. Here, the cross-section was observed after thawing, the amount of drip was measured, the breaking strength and breaking distance were measured, and a sensory evaluation was performed. Furthermore, these observations of the cross-section, measurement of breaking strength and breaking distance, and sensory evaluation were performed after the kamaboko had returned to room temperature of 19-21°C.
[0025] In the observation of the cross-sections after thawing, kamaboko that had been naturally thawed and kamaboko that had been boiled were sliced with a knife and observed. For comparison, the cross-section of kamaboko that had been refrigerated was also photographed. Figures 3(A) to 3(C) show the cross-sectional photographs, with Figure 3(A) being kamaboko that had been naturally thawed after freezing, Figure 3(B) being kamaboko that had been boiled for 20 minutes after freezing, and Figure 3(C) being kamaboko that had been refrigerated. Looking at these, it can be seen that there are many voids in the cross-section of the naturally thawed kamaboko shown in Figure 3(A). The largest of these voids was approximately 1.2 mm. This is smaller than the approximately 4 mm of ice crystals during freezing, and it is presumed that these voids are partially restored by the elasticity of the kamaboko. Next, looking at the cross-section of the boiled kamaboko shown in Figure 3(B), it can be seen that the voids are clearly smaller and fewer in number compared to the naturally thawed kamaboko. This indicates that the pores created by ice crystals during freezing are sealed during boiling and thawing.
[0026] For measuring the amount of drip, kamaboko (fish cake) that had been naturally thawed and kamaboko that had been boiled and thawed were separated into vacuum-sealed and non-vacuum-sealed storage bags. The weight of each was measured while they were in the vacuum-sealed bag or storage bag, and after thawing, any moisture adhering to the bags and kamaboko was wiped off, and they were placed back in the bags for measurement. This is because if the kamaboko is exposed to air, the moisture will evaporate, making accurate measurement impossible. Here, the amount of drip was calculated as the drip rate using the following formula, based on the weight Wo (g) of the kamaboko before freezing and the weight W (g) of the kamaboko after wiping off the moisture after thawing. Drip rate (%) = (Wo(g) - W(g)) / Wo(g) × 100(%)
[0027] These drip rates are shown in Figures 4(A) and 4(B). Figure 4(A) shows the results for vacuum-packed products, and Figure 4(B) shows the results for non-vacuum-packed storage bags. In vacuum-packed products, the drip rate was 4.8% with natural thawing and 2.3% with boiling thawing, indicating that boiling thawing reduces the drip rate. On the other hand, in non-vacuum-packed storage bags, the drip rate was 4.2% with natural thawing and 4.3% with boiling thawing, showing no difference between natural and boiling thawing. From these results, it can be seen that vacuum packaging is effective in suppressing the drip rate.
[0028] Next, we will explain the measurement results for breaking strength and breaking distance. Here, as shown in Figures 5(A) and 5(B), we compared kamaboko stored in the refrigerator, kamaboko that was vacuum-packed and thawed naturally, and kamaboko that was vacuum-packed and thawed by boiling. Figure 5(A) shows the breaking strength, and Figure 5(B) shows the breaking distance. For these breaking strength and breaking distance measurements, the kamaboko was cut to a thickness of approximately 15 mm near the center, and then further divided into three parts as shown in Figure 5(C). A 5 mm diameter spherical plunger of a rheometer (Rheotec Co., Ltd. NRM-2010J-CW) was placed on the center of the central piece of kamaboko from these three divisions to take the measurement. Three samples were measured, and the average value of each was calculated and plotted on a graph. From these measurement results, the boiled kamaboko showed a clearly higher breaking strength than the kamaboko that was thawed naturally. A slight recovery was also observed in the breaking distance. For specific numerical values, please refer to the tables in Figures 7(A) and 8(A).
[0029] Next, we will explain the results of the sensory evaluation. In this sensory evaluation, five evaluators assessed the appearance and elasticity when chewed for kamaboko stored in the refrigerator, kamaboko that was vacuum-packed and thawed naturally, and kamaboko that was vacuum-packed and thawed by boiling. For the appearance, please refer to the observation of the cross-section after thawing and Figures 3(A)~(C) above. Regarding the elasticity when chewed, all evaluators rated the refrigerated kamaboko as the best and the naturally thawed kamaboko as the worst. The boiled and thawed kamaboko came in the middle. In particular, regarding the naturally thawed kamaboko, there were comments such as "It's spongy and unpleasant," "The drip has a salty taste and is unpleasant," and "The drip is sticky when you chew it and it's unpleasant."
[0030] Although not shown in the diagram, in the observation of the cross-section after thawing, the fracture strength, and the sensory evaluation, the kamaboko frozen at -40°C and naturally thawed yielded better results than the kamaboko frozen at -20°C and naturally thawed, and the kamaboko frozen at -80°C and naturally thawed yielded even better results. This is thought to be because the lower the freezing temperature, the closer the freezing conditions are to rapid freezing. However, even the kamaboko frozen at -80°C showed signs of deterioration due to freezing compared to refrigerated kamaboko.
[0031] Next, to investigate the optimal thawing time, we conducted experiments using kamaboko (fish cake) (3% starch content by weight, 6 cm in diameter x 12 cm in length) that had been frozen at -20°C and stored for one week, varying the boiling thawing time between 10 and 40 minutes. For evaluation, we observed the cross-section after thawing, measured the breaking strength and breaking distance, and performed a sensory evaluation. The evaluation method was the same as described above.
[0032] Figures 6(A) to 6(D) show the results of cross-sectional observation after thawing. For comparison, please refer to Figures 3(A) and 3(C) for cross-sectional observations of kamaboko thawed naturally and stored in the refrigerator. Figure 6(A), which was boiled and thawed for 10 minutes, still showed a noticeable number of voids and a rough surface appearance. Figure 6(B), which was boiled and thawed for 20 minutes, showed a decrease in the number of voids and an improvement in appearance and quality. Figure 6(C), which was boiled and thawed for 30 minutes, showed an increase in the number of voids again. Figure 6(D), which was boiled and thawed for 40 minutes, showed even larger voids. From these results, the cross-sectional observation showed that the kamaboko boiled and thawed for 20 minutes was the best, followed by the kamaboko boiled and thawed for 30 minutes.
[0033] Next, the results of the fracture strength measurements are shown in Figures 7(A) and 7(B). Figure 7(A) is a table summarizing the measured values and average values of three kamaboko (fish cakes) that were stored in the refrigerator, thawed naturally, boiled for 10 minutes, boiled for 20 minutes, boiled for 30 minutes, and boiled for 40 minutes. Figure 7(B) is a graph of the table in Figure 7(A). These results show that the fracture strength was higher in boiling thawing compared to natural thawing at all heating times. In particular, the fracture strength recovered significantly after boiling for 20 minutes and 30 minutes, and it was determined that quality deterioration could be suppressed.
[0034] Next, the measurement results of the fracture distance are shown in Figures 8(A) and 8(B). Figure 8(A) is a table similar to Figure 7(A), and Figure 8(B) is a graph of the table in Figure 8(A). These results, like the fracture strength mentioned above, also showed that the fracture distance increased in boiling thawing compared to natural thawing, regardless of the heating time. In particular, the fracture distance recovered significantly after boiling thawing for 20 minutes and 30 minutes, and it was determined that quality deterioration could be suppressed.
[0035] Next, Figure 9(A) shows the results of the sensory evaluation for appearance, and Figure 9(B) shows the results for elasticity when chewed. Here, kamaboko (fish cake) was evaluated after refrigeration, natural thawing, boiling for 10 minutes, boiling for 20 minutes, and boiling for 30 minutes. Five evaluators evaluated these samples, assigning points as follows: 5 points for 1st place, 4 points for 2nd place, 3 points for 3rd place, 2 points for 4th place, and 1 point for 5th place. In other words, the highest score was 25 points and the lowest score was 5 points. Figures 8(A) and 8(B) show the total scores as bar graphs. As shown here, for frozen and thawed kamaboko, the one boiled for 20 minutes had the best appearance and elasticity, followed by the one boiled for 30 minutes.
[0036] Based on the observation of the cross-section after thawing, the measurement of breaking strength and breaking distance, and the results of the sensory evaluation, boiling for 20 minutes yielded the best results, followed by boiling for 30 minutes. Boiling for 10 minutes and boiling for 40 minutes also yielded better results than natural thawing, indicating that boiling has the effect of recovering from freezing damage to kamaboko. In the observation of the cross-section after thawing, the measurement of breaking strength and breaking distance, and the sensory evaluation, boiling for 20 minutes and 30 minutes were optimal, but this time is thought to vary depending on the size and thickness of the kamaboko, as well as the freezing temperature. Therefore, if the kamaboko is small and the freezing temperature is high, boiling for 10 minutes will yield good results, while if the kamaboko is large and the freezing temperature is low, boiling for more than 30 minutes will yield better results.
[0037] While the mechanism of quality improvement achieved by implementing the preservation method for processed seafood products of this embodiment remains unclear, two possibilities can be hypothesized. The first is due to the thermal behavior of starch granules used as a secondary ingredient in processed seafood products. When heated, starch granules absorb surrounding free water, increasing their fluidity (gelatinization). It is quite conceivable that these gelatinized and swollen starch granules fill the holes created by ice crystals, acting as a filler to repair damage to the three-dimensional network of muscle proteins. The second possibility is repair through the expansion of the kamaboko itself due to boiling. The preservation method for processed seafood products of this embodiment requires vacuum packaging. Vacuum packaging may increase the effect of sealing holes by directing the expansion pressure inward.
[0038] As explained above, the preservation method for processed seafood products of this embodiment allows for improved quality even with slow freezing, does not require the use of special equipment or processes, and can reduce costs in distribution. Furthermore, even with rapid freezing, the quality does not fully recover after normal thawing, and some impact is expected. For example, as already mentioned, rapid freezing means passing through the maximum ice crystal formation temperature zone within 30 minutes, but there will naturally be a difference in the quality of kamaboko after thawing between kamaboko that passed through the maximum ice crystal formation temperature zone in 1 minute and kamaboko that passed through it in 29 minutes. Leaving aside freezing methods using liquid nitrogen as described in the background technology section, it is considered that even with rapid freezing, 100% quality recovery is not possible after thawing. Even in such cases, using the preservation method for processed seafood products of this embodiment makes it possible to provide higher quality processed seafood products.
[0039] The method for preserving processed seafood products in this embodiment is illustrative of the present invention, and its configuration can be appropriately modified without departing from the spirit of the invention.
Claims
1. The vacuum packaging process involves vacuum packaging processed seafood products in packaging bags, A freezing process for freezing the aforementioned processed seafood product, A thawing process in which the frozen processed seafood product is boiled and thawed while still in its vacuum packaging, A method for preserving processed seafood products, characterized by containing [a certain ingredient].
2. The method for preserving processed seafood products according to claim 1, wherein the freezing is slow freezing.
3. A method for preserving processed seafood products according to claim 1 or 2, wherein the time for the thawing step is 10 minutes or more and 40 minutes or less.
4. The method for preserving processed seafood products according to claim 1 or 2, wherein the time for the thawing step is 20 minutes or more and 30 minutes or less.