JP2011172598A - Delicious shrimp and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a processing method for preparing fresh shrimps having improved taste which can be easily introduced during a processing procedure while keeping freshness independent of natural or cultured articles and kinds of shrimps, and to provide general processed articles including fresh, frozen and heated shrimps having improved taste. <P>SOLUTION: There are provided shrimps containing 5'-inosinic acid (IMP) at a ratio of ≥40% based on nucleic acid-relating substances and having improved taste and a method for producing the shrimps containing 5'-inosinic acid (IMP) at a ratio of ≥40% based on nucleic acid-relating substances and having improved taste by keeping shrimps at 10-50°C for 0.1-24 hours. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to shrimps having a high IMP content and improved taste. The present invention also relates to a treatment method for enhancing the umami of fresh products or frozen shrimps.

  In Japan, various and various forms of shrimp are imported and produced regardless of natural farming, processed and consumed as side dishes such as sushi, tempura, and fries. Japan has long been a world-class shrimp consumer.

  The reason why shrimp are preferred in Japan is that the unique taste and texture of shrimp match the taste of Japanese people.

  The taste of shrimp is free amino acids such as glycine, alanine, and glutamic acid, IMP, nucleic acid-related substances such as adenosine-phosphate (AMP), betaine, and organic acids. The shrimp has a strong sweetness and umami, and is preferred.

  Therefore, in order to increase the commercial value of shrimp at the processing site, they are immersed in a seasoning liquid (dipping solution) containing glycine, alanine, glutamic acid, etc., among the free amino acids contained in shrimp, and these components are processed at the processing stage. A method for increasing the content and improving the taste has been attempted.

  However, shrimp seasoned by this method have disadvantages that the flavor is not like the original shrimp and that the taste is easily lost during cooking.

  On the other hand, shrimp with a high free amino acid content and improved sweetness and umami have been invented by breeding livestock shrimp immediately after landing with breeding water having a higher salt concentration than breeding water for a certain period of time (Patent Document 1). reference). The shrimp obtained by this method has more free amino acids than the conventional livestock shrimp and has a natural flavor.

  However, in the present invention, there is a case where it is molted by high osmotic pressure stress, the shrimp that can be targeted is limited to live shrimp in livestock farming, and a farm with a series of processes from aquaculture to processing It is not a method that can be applied to edible shrimp processing in general from a variety of production forms, such as being unable to implement unless it is not possible (generally, the aquaculture pond is often separated from the processing plant and is not versatile).

  Next, regarding nucleic acid-related substances that greatly affect the taste of fish apart from free amino acids, IMP in nucleic acid-related substances generally accumulated in fish is synergistic with glutamic acid (Glu), a free amino acid. It is already well known that it has the effect of enhancing umami. In fish, the adenosine triphosphate (ATP) in the body is rapidly decomposed into post-mortem adenosine diphosphate (ADP) → AMP → IMP by being left at low temperature, and is temporarily accumulated as IMP. Taste is enhanced. However, when time passes for a long time or when left at high temperature, decomposition into inosine (HxR) and hypoxanthine (Hx) proceeds, the freshness decreases, and the K value, which is an index of freshness, also increases.

  By the way, when shrimp are left at a low temperature, both AMP and IMP accumulate, and only IMP does not become rich like fish. AMP, which is temporarily accumulated in shrimps, also has a synergistic effect of umami with Glu. However, the effect is greatly different from IMP, and it is known that the synergistic effect of AMP is limited to 18% when IMP is set to 100% (see Non-Patent Document 1).

  As a result of research reports on the changes in nucleic acid components after the death of prawns (see Non-Patent Document 2), the accumulation rate (%) of IMP at each temperature in the longest storage time is 144 hours at -3 ° C storage (%) 42% for 6 days), 43% for 144 hours at 0 ° C (6 days), 36% for 48 hours (2 days) at 5 ° C, 33% for 24 hours (10 days) at 10 ° C, 10 ° C It is known that IMP does not accumulate at the following low temperatures unless a very long time is required. However, in actual manufacturing, if stored for such a long time, the blackening problem peculiar to shrimp occurs, and the K value, which is an index of freshness, is considered to exceed 20%, and there is a risk that the commercial value may be lost. Microbial problems are also a concern in actual production situations.

  Furthermore, in the case of prawns, the above-mentioned documents have already been reported, but for the two types of commercially important shrimp, black tiger and vanamae shrimp, publicly known information related to changes in nucleic acid components after death There was no situation at all.

Japanese Unexamined Patent Publication No. 07-170886

SHINGO IKEDA and TSUNEHIKO NINOMIYA, JOURNAL OF FOOD SCIENCE-VOLUME36 (1971) Misuzu Matsumoto, Hideaki Yamanaka, "Study on post-mortem stiffness of prawns", Nippon Suisan Gakkaishi, 57 (11), 2121-2126 (1991)

  The problem to be solved by the present invention is to provide a treatment method for producing fresh shrimp with enhanced taste that can be easily introduced into the processing process while maintaining freshness regardless of the type of natural, aquaculture or shrimp. , Provides all processed shrimp products such as fresh, frozen and heated products with enhanced umami.

  First, the inventors focused on the difference in taste even in the same kind of shrimp, and investigated the relationship between the shrimp's taste component and taste. As a result, it was discovered that the difference in the composition ratio of the nucleic acid-related substances affects the taste, particularly umami, from the amount of free amino acids and the total amount of free amino acids exhibiting taste. Specifically, in the case of frozen and fresh shrimp, the total amount of nucleic acid-related substances is 8 to 12 μmol / g, most of which (> 80%) is AMP and IMP. It was discovered that IMP tends to contain more AMP than AMP.

  Therefore, as a result of intensive research on processing methods to create an IMP rich state using shrimp with a high ATP, ADP, AMP and IMP content, that is, a state with a K value of 20% or less, the shrimp is kept in a certain temperature range for a certain period of time. By holding, the present invention for obtaining shrimp with a small increase in K value (small accumulation of HxR / Hx) and significantly increased IMP has been completed. That is, the inventors have invented a method for accumulating a high concentration of IMP in a shrimp body by suppressing the reaction of IMP → HxR while promoting the reaction of AMP → IMP.

  The shrimp with increased IMP in this invention has a strong umami advantage compared to the shrimp before the increase, and it is easier to become a shrimp with a strong flavor with the original flavor of shrimp than the method of increasing free amino acids that has been done so far I found it.

That is, the aspects of the present invention are as follows.
[1] Shrimp with enhanced umami taste in which the proportion of 5'-inosinic acid (IMP) in nucleic acid-related substances is 40% or more.
[2] The shrimp according to [1], which has a K value of 20% or less.
[3] The shrimp according to [1] or [2], wherein the absolute concentration of IMP is 3 μmol / g or more.
[4] A fresh product, a frozen product, or a heat-processed product using the shrimp of any one of [1] to [3].
[5] The shrimp according to any one of [1] to [4], wherein the shrimp belongs to the genus Penaeus.
[6] The shrimp of [5], wherein the shrimp belonging to the genus Penaeus is any one of black tiger (Penaeus monodon), tiger prawn (Penaeus japonicus), Thai shrimp (Penaeus chinensis), and Banamei (Penaeus vannamei). .
[7] The shrimp according to any one of [1] to [4], wherein IMP is accumulated in the shrimp body by holding the shrimp at a temperature of 10 to 50 ° C. for 0.1 to 24 hours. Production method.
[8] The method for producing shrimp according to [7], wherein IMP is accumulated in the shrimp body by holding the shrimp at a temperature of 15 to 40 ° C. for 0.1 to 10 hours.
[9] The method for producing a shrimp according to [7] or [8], wherein the K value of the shrimp is further suppressed to 20% or less.
[10] Nucleic acid-related ATP → ADP → AMP → IMP → HxR → Hx occurring after death in shrimp, characterized by holding shrimp at a temperature of 10-50 ° C. for 0.1-24 hours In the reaction of substances, AMP → IMP reaction is promoted, IMP → HxR reaction is suppressed, and IMP is accumulated in shrimps.
[11] The method according to [10], wherein the shrimp is maintained at a temperature of 15 to 40 ° C. for 0.1 to 10 hours.
[12] Shrimp produced by the method of [10] or [11].

  According to the present invention, by maintaining various shrimp at an intermediate temperature of 15 to 40 ° C., high concentration of IMP can be accumulated in a relatively short time, and the flavor of shrimp can be further enhanced. Shrimp, unlike fish, have the property that IMP is difficult to accumulate, and it takes a long time at temperatures below 10 ° C, and conversely, problems such as blackening occur. Alternatively, at a high temperature of 40 ° C. or higher, IMP increases even by treating for a very short time, but HxR is also generated, and conversely, it is not efficient in the sense of accumulating a high concentration of IMP. The present invention provides a method capable of accumulating a high concentration of IMP by setting just an intermediate temperature to the storage temperature after shrimp death, and also provides a savory shrimp containing a high concentration of IMP. Is.

It is a figure which shows the change of AMP and IMP density | concentration which occur when the frozen product with cultured black tiger shrimp headless shell is stored at 0 degreeC. It is a figure which shows the change of AMP and IMP density | concentration which occur when the frozen product with cultured black tiger shrimp headless shell is stored at 25 degreeC. It is a figure which shows the change of AMP and IMP density | concentration which occur when the frozen product with cultured black tiger shrimp headless shell is stored at 45 degreeC. It is a figure which shows the relationship between IMP% and K value which occur during each temperature storage of black tiger frozen shrimp. It is a figure which shows the storage temperature dependence of K value at the time of 40% IMP accumulation | storage of black tiger frozen shrimp. It is a figure which shows the change of the AMP and IMP density | concentration which occur when the frozen product with a cultured shrimp headless shell is stored at 0 degreeC. It is a figure which shows the change of AMP and IMP density | concentration which occur when the culture | cultivated vaname shrimp uncrashed frozen goods are stored at 25 degreeC. It is a figure which shows the change of AMP and IMP density | concentration which occur when the culture | cultivation vanamae shrimp uncrashed frozen product is stored at 55 degreeC. It is a figure which shows the relationship between IMP% and K value which occur during each temperature storage of frozen frozen shrimp. It is a figure which shows the storage temperature dependence of K value at the time of 40% IMP accumulation | storage of vaname frozen shrimp. It is a figure which shows the change of AMP and IMP density | concentration which occurs when the frozen product with a prawn headless shell is stored at 10 degreeC. It is a figure which shows the change of AMP and IMP density | concentration which occurs when the frozen product with a prawn headless shell is stored at 25 degreeC. It is a figure which shows the change of AMP and IMP density | concentration which occurs when the frozen product with a head shrimp of prawns is stored at 45 degreeC. It is a figure which shows the change of AMP and IMP density | concentration which occurs when a prawn with a headless shell is stored at 10 degreeC. It is a figure which shows the change of AMP and IMP density | concentration which occur when a prawn with a headless shell is stored at 20 degreeC. It is a figure which shows the change of AMP and IMP density | concentration which occurs when a black tiger shrimp with a headless shell is stored at 7 degreeC. It is a figure which shows the change of AMP and IMP density | concentration which occurs when a black tiger shrimp with a headless shell is stored at 20 degreeC. It is a figure which shows the change of AMP and IMP density | concentration which arises when a vanilla shrimp with a headless shell is stored at 7 degreeC. It is a figure which shows the change of AMP and IMP density | concentration which arises when a vanilla shrimp with a headless shell is stored at 20 degreeC.

  The shrimp used as a raw material in the present invention is a non-livestock aquaculture, a natural edible shrimp, which may be a fresh product or a frozen product, and may be any form of decapitation / headed, shelled / dehulled product, What dropped the head is preferable. The type of shrimp is not limited, but shrimp belonging to the genus Penaeus is preferable, and black tiger (Penaeus monodon), prawn (Penaeus japonicus), Thai shrimp (Penaeus chinensis), and Banamei (Penaeus vannamei) are more preferable.

  For shrimp, frozen products are thawed, fresh products are left as they are, live ones are cooked, and the product temperature is 10 to 50 ° C., preferably 15 to 40 ° C., 0.1 to 24 hours, preferably Keep for 0.1-10 hours. In the case of black tiger, 15 ° C to 25 ° C is preferable, and in the case of Banamei, 15 ° C to 40 ° C is preferable. Examples of suitable combinations of temperature and time during shrimp storage include combinations at 25 ° C. for 1 hour or 2 hours or more.

  By maintaining the above temperature for the above time, IMP can be accumulated without accumulating AMP. That is, after shrimp death, the nucleic acid-related substance in the shrimp changes mainly from ATP → ADP → AMP → IMP → HxR → Hx. In addition, there is a route in which the reaction proceeds in the middle of the reaction route from AMP → adenosine → HxR without going through IMP. According to the method of the present invention, the AMP → IMP reaction is promoted in the shrimp and the IMP → HxR reaction is suppressed, so that shrimp having a high IMP content and a low HxR and Hx content can be produced. In this case, the suppression of the reaction of IMP → HxR means that the reaction of AMP → IMP proceeds relatively preferentially over the reaction of IMP → HxR in a series of reactions of AMP → IMP → HxR. Say. Conversely, at temperatures below 10 ° C or above 50 ° C, the IMP → HxR reaction occurs preferentially over the AMP → IMP reaction, so the IMP content does not increase.

  At this time, it is preferably sealed in a plastic bag or the like for the purpose of preventing drying. Alternatively, in order to quickly bring the product temperature to the target temperature, immerse it in a solution containing 3-20% salt adjusted to 30 ° C to 40 ° C and wait for the shrimp temperature to reach the target temperature. Then, drain the solution and leave it at room temperature.

  In this process, the amount of IMP, which is an umami enhancing component among the nucleic acid-related substances in shrimp, increased predominately, becoming 40% or more of all nucleic acid-related substances, ie, nucleic acid components, and enhancing the umami of glutamic acid contained in shrimp In the meantime, you can make shrimp with a strong taste. That is, the shrimp of the present invention is a shrimp in which the amount of IMP in the total nucleic acid-related substance is 40% or more, preferably 42% or more, more preferably 45% or more. Here, the nucleic acid-related substances include ATP, ADP, AMP, HxR (inosine), Hx (hypoxanthine) and IMP. The amount of IMP in shrimp refers to the amount of IMP in shrimp muscles.For example, the back and intestines are removed at the same time while separating the chest and abdomen, and the crust that covers the abdomen is removed. What is necessary is just to analyze as the analysis part the part which removed the node part, the sixth part part, and the muscle part of the tail joint. In the present invention, the amount of nucleic acid-related substance in shrimp is a value analyzed in this way.

Further, the absolute amount of IMP in the shrimp of the present invention is 3 μmol / g or more.
Also, by this treatment, there is almost no elution of components such as free amino acids in shrimp, and no change in the total amount of free amino acids is observed.

  Furthermore, the shrimp of the present invention is a shrimp having a K value of 20 or less. Here, the K value is a value that serves as an index of freshness, and is represented by K value (%) = (HxR + Hx) / (ATP + ADP + AMP + IMP + HxR + Hx) × 100. Generally, when the K value is 20 or less, it is suitable for raw eating, and the shrimp of the present invention can be eaten raw.

  Furthermore, examples of the composition of the shrimp nucleic acid-related substance of the present invention include a composition in which the amount of IMP is 40 to 60%, AMP is 20 to 40%, and HxR + Hx is 20% or less.

  The shrimp of the present invention has a feature that umami is enhanced or whether umami is enhanced is determined by performing a sensory test such as a two-point discrimination test method or a quantitative description analysis method. be able to.

  The shrimp processed in this way may be frozen as it is after cooking, to make a frozen product, or of course, cooked as it is. When the shrimp obtained in the present invention is processed into sushi shrimp, it enhances the umami of glutamic acid in soy sauce, and becomes sushi shrimp with a stronger umami. In addition, even if it is processed into tempura and fried food, it becomes a processed product with strong taste as well, or even when used in ingredients such as Chinese ingredients and soup, the taste of the whole cooked product is increased, making it extremely simple and sufficient. It is a useful technique that can improve the taste.

  The present invention will be specifically described by the following examples, but the present invention is not limited to these examples.

Example 1
Analysis of the composition of nucleic acid components in shrimp was carried out by the following method. First, an analytical sample was collected from shrimp by removing the back and intestines at the same time while separating the thorax and abdomen, and then removing the crust covering the abdomen. Furthermore, the site | part which removed the 1st node site | part of the abdomen, the 6th node site | part, and the muscle site | part of the tail node was sampled as an analysis site | part.

  Next, the nucleic acid component was extracted by adding 20% of 5% trichloroacetic acid cooled in ice water to the weight of the collected shrimp and immediately homogenizing to obtain a suspension. The obtained suspension is centrifuged (3,000 rpm for 15 minutes (4 ° C) in a domestic swing centrifuge), and the liquid part obtained as a supernatant is filtered (0.2 μm) for nucleic acid analysis. It used for HPLC (high performance liquid chromatography).

As for the contents of HPLC, the column used (temperature used) is GS-320HQ (30 ° C) manufactured by Shodex Asahipak, the eluent composition is 200 mM phosphoric acid solution pH 2.9, the flow rate is 0.6 ml / min, and it is absorbed by the UV detector. Detection was performed at a wavelength of 260 nm. For calculation of quantitative values, Windows compatible software EZChrom Elite was used. The K value or IMP (%) was calculated from the quantitative value (μmol / g) of each nucleic acid component according to the following formula.
K value (%) = (HxR + Hx) / (ATP + ADP + AMP + IMP + HxR + Hx) x 100
IMP (%) = IMP / (ATP + ADP + AMP + IMP + HxR + Hx) × 100

Example 2
IQF-frozen (frozen one-by-one frozen) cultured black tiger shrimp frozen products with headless shells (size 31/41 tails) were thawed in running water at 20 ° C for 20 minutes, drained and then iced When cooled and boiled for 3 minutes in boiling water (unripe section) and when shredded shrimp are sealed in a plastic bag and stored for 2 hours in a thermostat set at 20 ° C (aged section) The free amino acids and nucleic acid components were analyzed for) and shown in Table 1.

  As a result, the total free amino acid concentration, the total nucleic acid concentration, and the K value were not significantly different. On the other hand, in terms of nucleic acid composition, AMP was 53.6% and IMP was 27% in the immature group, but AMP was 26.8% and IMP 55.4% in the matured group. The ratio was reversed and IMP accumulation was clearly observed.

Example 3
In both test sections of Example 2, sensory evaluation was performed by a two-point discrimination test method. As a result of comparing the umami according to Table 2, 20 people out of 26 evaluated that the shrimp in the aged area had stronger umami. It was confirmed that the shrimp in the ripening zone was statistically strong at 1% significance level.

Example 4
When IQF-frozen cultured vanname prawns (31/41 tails) are thawed in running water at 20 ° C for 20 minutes, drained and then ice-cooled and heated in boiling water for 3 minutes ( When the 5% saline solution prepared at 30 ° C, which is twice the amount, is added to the shrimp after draining, and left to stand for 2 hours, drained again and heated (aging) Table 3 shows the analysis of free amino acids and nucleic acid components.

  As a result, there was no significant difference in the total free amino acid concentration and the total nucleic acid concentration, and an increase in the matured area was observed in the K value, but the value was 10% or less. On the other hand, in terms of nucleic acid composition, AMP was 77.4% and IMP 7.6% in the immature group, but it was AMP 33.6% and IMP 51% in the matured group. The ratio of IMP to IMP was reversed, and IMP accumulation was clearly observed.

Example 5
For the boiled lobster in both test areas of Example 4, a quantitative descriptive analysis method (“Current Status and Prospect of Sensory Evaluation Technology” by Goro Aijima, Monthly Food Chemical, Vol.18, No1, ( 2002)). In other words, 13 specific panels were gathered in one place, eaten shrimp in both test areas, and discussed the appropriate evaluation words to evaluate the taste difference between the two shrimp. 2 items of sweetness and umami were appropriate, and it was confirmed that the evaluation words can be recognized by everyone. And again, sensory evaluation by individual panelists was conducted for these two items. The results are shown in Table 4, and it was evaluated that shrimp in the matured area clearly felt stronger in all two items of sweetness and umami. As a result, a clear sensory difference was confirmed at a significance level of 5% for umami and 1% for sweetness.

  From the above results, it was demonstrated that by increasing the amount of IMP in various nucleic acid components contained in shrimp, the umami taste of the shrimp was clearly enhanced functionally.

Example 6
Next, we examined in detail the storage temperature at which IMP was efficiently accumulated using frozen products of each shrimp.
IQF frozen cultured black tiger shrimp with a headless shell (size 31/41 tails) was thawed in running water at 20 ° C for 20 minutes, drained and then ice-cooled, 0 ° C, 25 ° C, 45 ° C In Fig. 1-1 to Fig. 1-3, the changes over time of the nucleic acid components were traced and the changes over time of the nucleic acid components were traced. Although there is a difference in speed depending on the storage temperature, AMP (◯) decreased with the passage of storage time at any temperature. On the other hand, IMP (●) and IMP% (△) increased only slightly at 0 ° C and 45 ° C, and IMP did not reach 40%. At 25 ° C, it increased with time, and IMP (%) reached 55% at maximum.

Example 7
In addition to the data of Example 6, the data stored at temperatures of 5 ° C., 10 ° C., 15 ° C., 20 ° C., 30 ° C., 35 ° C., 40 ° C., 50 ° C. and 55 ° C. are also added to the IMP (% ) And the accompanying increase in the K value are shown in FIG. As a result, at 15 ° C to 25 ° C, the IMP (%) reaches a maximum at a little less than 60% when the K value is in the range of 10 to 15%, and as the temperature goes away from the storage temperature, the accumulated IMP (%) The maximum value was lowered. Further, from the result of FIG. 2, the K value when the IMP reached 40% was read, and the relationship with the storage temperature is shown in FIG. However, the temperature at which IMP did not reach 40% is indicated by a circle, and the longest storage time and the K value at that time are entered in () next to each symbol. According to this result, IMP did not reach 40% at temperatures of 0 ° C., 5 ° C., 45 ° C., 50 ° C. and 55 ° C. In the temperature range from 10 ° C. to 40 ° C. where IMP (%) reached 40%, U-shaped dependence on temperature was exhibited. In other words, in the case of black tiger shrimp, IMP reaches 40% at a low K value (5 to 10%) in the temperature range of 15 ° C to 25 ° C. As the temperature increased and the temperature further increased, only the K value increased, but IMP became difficult to increase.

Example 8
IQF-frozen cultivated vaname shrimp with a headless shell (size 31/41 tails) is thawed in running water at 20 ° C for 20 minutes, drained and stored at 0 ° C, 25 ° C and 55 ° C for a specified time. The change with time of the nucleic acid component was traced, and the results are shown in FIGS. 4-1 to 4-3. Although there is a difference in speed depending on the storage temperature, AMP (◯) decreased with the passage of storage time at any temperature. On the other hand, IMP (●) and IMP% (△) increased only slightly at 0 ° C and 45 ° C, and IMP did not reach 40%. At 25 ° C, it increased with time, and IMP (%) reached a maximum of slightly less than 55%.

Example 9
In addition to the data of Example 8, the data stored at temperatures of 5 ° C., 10 ° C., 15 ° C., 20 ° C., 30 ° C., 35 ° C., 40 ° C., 45 ° C. and 50 ° C. are also added to the IMP (% ) And the accompanying increase in K value is shown in FIG. As a result, at 20 ° C to 40 ° C, the K value is in the range of 10% to 15%, the IMP (%) becomes a maximum just over 60%, and the maximum value of the IMP (%) increases as the temperature goes higher and lower than that range. Became lower. Moreover, the value of K value when IMP reached 40% was read from the result of FIG. 5, and the relationship with the storage temperature was shown in FIG. However, the temperature at which IMP did not reach 40% is indicated by a circle, and the longest storage time and the K value at that time are entered in () next to each symbol. According to this result, the IMP did not reach 40% at temperatures of 0 ° C., 5 ° C., and 55 ° C. In the temperature range from 10 ° C. to 50 ° C. where IMP (%) reached 40%, U-shaped dependence on temperature was exhibited. In other words, in the case of shrimp, IMP reaches 40% at a low K value (5 to 10%) in the temperature range of 15 ° C to 40 ° C. As the temperature further increased, only the K value increased, but IMP was less likely to increase.

Example 10
IQF-frozen frozen prawns (size 31/41 tails) were thawed in running water at 20 ° C for 20 minutes, drained, and stored at 10 ° C, 25 ° C, 45 ° C for a specified period of time. Changes in the components over time were traced, and the results are shown in FIGS. 7-1 to 7-3. At any temperature, AMP (◯) once reached its maximum value at the beginning of storage. This is because the shrimp immediately after thawing used in this experiment contained a large amount of ATP, and ATP rapidly decomposed in the early stage of storage, and AMP temporarily accumulated in the initial stage of storage. Thereafter, AMP decreased with time. On the other hand, IMP (●) increased with the passage of time from the beginning of storage, and at 10 ° C and 25 ° C storage, the absolute concentration and ratio increased to the same level, but at 45 ° C the increase in IMP was small. .

  From the above results, as an effective treatment method for efficiently storing IMP in frozen shrimp, by adjusting the storage temperature after thawing, decomposition reaction from AMP to IMP occurs efficiently, and as a result It was found that IMP can accumulate at high concentration. Although there is a difference of around 5 ° C depending on the kind of shrimp, the optimum temperature range is 10 ° C to 50 ° C, and the temperature at which higher concentration of IMP can be accumulated in that range is 15 ° C to 40 ° C Met. In other words, it was found that in the storage at a lower temperature or higher temperature, the increase in the K value accompanying the increase in the amount of accumulated IMP occurs, so that it is difficult to efficiently accumulate IMP and the maximum amount of accumulation decreases.

Example 11
Live prawns were killed by ice for 1 hour, and the head and back intestine were removed to make shrimp with a headless shell. This was stored at 10 ° C. and 20 ° C., and changes with time of the nucleic acid components were followed. The results are shown in FIGS. 8-1 and 8-2. When stored at 10 ° C, AMP (◯) was hardly produced, but IMP (●) accumulated after 400 minutes (about 6.5 hours) of storage. This is because immediately after the killing of live prawns, most of the ATP was contained in the nucleic acid composition and maintained that state until 400 minutes of storage, after which a sharp decrease in ATP occurred, and IMP started accumulating accordingly. . On the other hand, at 20 ° C, ATP was mostly at the beginning of storage, but IMP accumulation started from a shorter storage time than 10 ° C storage, and up to 70% of IMP (%) accumulated at the maximum.

Example 12
Black tiger shrimps that have been killed in ice after raising the ponds and stored for 5 to 5 hours are stored at 7 ° C and 20 ° C. The results are shown in FIGS. 9-1 and 9-2. At any temperature, AMP increased once at the beginning of storage, and IMP (●) was accumulated as AMP (○) decreased. However, the maximum concentration of AMP was 20 ° C rather than 7 ° C. And the composition ratio increased.

Example 13
After ponding, the shrimp with the head and back intestine, with the head and back intestines removed, is stored at 7 ° C and 20 ° C, and changes over time in the nucleic acid components are traced. The results are shown in FIGS. 10-1 and 10-2. At any temperature, AMP (○) once increased at the beginning of storage, and IMP (●) was accumulated as AMP decreased. However, when viewed at the maximum value, the absolute concentration of IMP was 20 ° C rather than 7 ° C. And the composition ratio increased.

  From the above results, even in the case of various types of unfrozen shrimp, accumulation of IMP at a higher concentration was confirmed at the optimum storage temperature examined with frozen shrimp.

Claims (7)

  Shrimp with enhanced umami, in which the proportion of 5'-inosinic acid (IMP) in the ATP-related substance is 50% or more and IMP is contained more than AMP.   The shrimp according to claim 1, obtained by holding the shrimp at a temperature of 15 to 25 ° C for 0.1 to 24 hours.   The shrimp according to claim 1 or 2, having a K value of 20% or less.   The shrimp according to any one of claims 1 to 3, wherein the absolute concentration of IMP is 3 µmol / g or more.   The shrimp according to any one of claims 1 to 4, wherein the shrimp belongs to the genus Penaeus.   The shrimp according to claim 5, wherein the shrimp belonging to the genus Penaeus is any one of black tiger (Penaeus monodon), tiger shrimp (Penaeus japonicus), tiger shrimp (Penaeus chinensis), and Penaeus vannamei.   A processed product selected from the group consisting of a fresh product, a frozen product, and a heat-processed product using the shrimp according to any one of claims 1 to 6.