JPS6296073A - Method of preserving quality of laver - Google Patents

Abstract

PURPOSE:To preserve improved flavor of laver for a long period while preventing deterioration in quality, by drying raw layer in two stages to adjust water content to <= a given value, sealing the laver within an inert gas and preserving it. CONSTITUTION:Raw laver is primarily dried at <=45 deg.C to adjust water content to 8-16wt% and secondarily dried at <=45 deg.C to adjust water content to <=6wt%. Then, the dried laver is sealed within one or more inert gases such as N2, CO2, etc., and preserved at <=20 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention 1] The present invention relates to a method for preserving the quality of seaweed that can improve the flavor of seaweed and preserve the flavor for a long period of time.

[Technical background of the invention and its problems] The most common process for collecting seaweed fronds from the sea and manufacturing them into seaweed products sold on the market is a conventional method. That is, seaweed leaves picked at a fishing ground are cut into sheets and then dried until the moisture content is approximately 8 to 12% by weight to form dried seaweed.

This is called secondary drying. This dried seaweed cannot be stored as it is, so it is subjected to a drying process called secondary drying or pasteurization to reduce the moisture content to about 3 to 5% by weight, and then stored in a moisture-proof bag etc. at room temperature. In recent years, frozen storage has also been attempted in some cases. This secondary drying usually involves blowing hot air at a temperature of 60 to 80 degrees Celsius, and the product temperature is about 5 degrees.
It is carried out under conditions such that the temperature is 0°C or higher.

By the way, seaweed can only be harvested during the winter at fishing grounds, so in order to sell it throughout the year, it is necessary to maintain its quality close to that at the time of production for at least one year. However, with conventional methods, it has been impossible to preserve seaweed for a long period of time while retaining its fresh flavor.

[Object of the Invention] The present invention has been made in response to the above-mentioned situation, and an object of the present invention is to provide a method for maintaining the quality of seaweed that can improve the flavor of seaweed compared to the past and maintain the flavor for a long period of time. This is the purpose.

[Structure of the Invention] As a result of research into a method for preserving the good flavor of seaweed for a long period of time, the present inventors found that the secondary drying and secondary drying were carried out at a temperature of 4.
If the temperature is below 5℃, the original flavor of the seaweed will not be lost, and in order to retain this flavor for a long period of time, the seaweed that has undergone this secondary drying process should be heated with one or more types of inert gas. The present inventors discovered that it is necessary to seal the container inside the container or store it at a temperature of 20° C. or lower, leading to the present invention.

That is, in the present invention, after drying raw seaweed at a product temperature of 45°C or lower and adjusting the water content to 8 to 16% by weight,
Re-dried at a temperature of 5°C or below to adjust the moisture content to 6% or less, and store it sealed in one or more inert gases or at a temperature of 20°C or below. This invention relates to a method for maintaining the quality of seaweed, which improves the flavor of seaweed and maintains its quality for a long period of time by preserving it. Here, the material temperature refers to the surface temperature of the seaweed. Further, as the inert gas, nitrogen gas or carbon dioxide gas is preferable.

[Examples of the Invention] Experimental Example 1 Primary drying and secondary drying were performed at various product temperatures, and the flavor of seaweed was tested immediately after secondary drying, after 6 months of storage, and after 12 months of storage. Testing was performed using both panel testing and gas chromatography.

In the experiment, the temperature of the seaweed was 35℃, 40'C, 45℃25
Primary drying is performed by setting conditions such that the temperature is 0°C, 160°C, and then the temperature of the seaweed is 35°C, 240°C, 45°C, 50°C, and 60°C after each primary drying. Secondary drying was performed. obtained in this way)
A panel test was conducted on the flavor of moss when it was stored in nitrogen gas at an ambient temperature of 10°C or 25°C (hereinafter referred to as "N2 storage") and when it was stored in air (hereinafter referred to as "aerated storage"). At the same time, the methyl mercaptan content was measured using a gas chromatograph.

The results of the panel test are shown in the table below. The evaluation is on a 5-level scale, and the higher the value, the better the quality.

As is clear from the above table, the flavor is excellent when the product temperature is 45°C or lower during both primary drying and secondary drying, and when this is stored with N2 and air-filled storage at 10°C. In this case, the flavor was well retained over a long period of time.

On the other hand, the results of measuring the methyl mercaptan content in Sea H by gas chromatography are shown in Figures 1-5. The reason why we focused on the content of methyl mercaptan in determining the quality of seaweed is that as the quality of seaweed deteriorates, the levels of volatile sulfur-containing compounds such as hydrogen sulfide, methyl mercaptan, and dimethyl sulfide change. The quality of seaweed can be determined by measuring methyl mercaptan, especially in the case of methyl mercaptan, which is hardly present in fresh seaweed and its amount increases as the quality deteriorates. This is based on the results of the present inventor's discovery that it is possible to know directly, and when methyl mercaptan is 21)t)m or more, it can be determined that quality deterioration is obvious.

Figure 1 shows the relationship between the temperature of the secondary dried product and the amount of methyl mercaptan when the product is primarily dried at a temperature of 35° C. for various storage methods. When a is stored with air at 25°C, b is stored with N2 at 25°C, C is stored with air at 10°C, d is io'c and N2. The results are obtained after storage for 12 months. Figure e shows the result immediately after the secondary drying. Figure 2 shows the case of primary drying at a product temperature of 40°C, and Figure 3 shows the case of primary drying at a product temperature of 45°C.
Figure 4 shows the relationship between the amount of methyl mercaptan and the secondary drying temperature when primary drying is performed at a product temperature of 50°C, and Figure 5 shows the relationship between the amount of methyl mercaptan and secondary drying temperature when primary drying is performed at a product temperature of 60°C. , b, C, da and e have the same meanings as in FIG.

As is clear from Figures 1 to 5, when primary drying and secondary drying are performed under conditions where the product temperature is 45°C or lower, the amount of methyl mercaptan immediately after drying is 1 Dp.
m or less and save them N2 or 10
When stored in air at 12°C, the amount of methyl mercaptan did not increase even after 12 months, and the quality did not deteriorate.

Example 1 Seaweed that was primarily dried to a temperature of 35°C, 40°C, and 45°C was heated to a temperature of 35°C, 40'C, and 45°C, respectively.
Secondary drying at 5℃ i: 4% moisture content
dried seaweed. These dried seaweed were placed in bags made of aluminum laminated film, 10 sheets each, until the residual oxygen concentration was 1.
% or less, the air in the bag was replaced with nitrogen gas, sealed, and stored at air temperature (22° C.) for 12 months. The aluminum laminate film used has an oxygen gas permeability of 0.1 Cm3/m2/24 hours/atll at 40'C.
l, water vapor permeability 0. I Cm3 /m2 /24 hours/atm. The results showed that all seaweeds retained good flavor without deteriorating in quality. For comparison, dry seaweed was prepared with primary and secondary drying temperatures of 50'C and 60C and stored in the same manner for 12 months, but the quality had deteriorated.

Comparative Example] Ten sheets of dried seaweed dried in the same manner as in Example 1 were placed in the same aluminum laminate bags as in Example 1, sealed and stored at 25° C. for 12 months without gas replacement. As a result, the taste and aroma were not good regardless of the drying temperature.

In particular, all seaweeds had an altered odor.

Example 2 10 pieces of dried seaweed dried in the same manner as in Example 1 were placed in the same aluminum laminate bags as in Example 1, sealed and stored at 10° C. for 12 months without gas replacement. As a result, no deterioration of quality was observed in any of the seaweeds, and in particular, the taste and aroma were better the lower the temperature during both secondary drying and secondary drying.

[Brief explanation of drawings]

Figure 1 shows the relationship between the secondary drying temperature and methyl mercaptan content of dried seaweed that was first dried at a temperature of 35°C, then secondary dried at various temperatures, and then stored. Product temperature 40
Figure 3 shows the relationship between the secondary v2 drying temperature and methyl mercaptan content of dried seaweed that was first dried at 45℃ and then stored after secondary drying at various temperatures. Figure 4 shows the relationship between the secondary drying temperature and methyl mercaptan content of dried seaweed that was first dried and then stored after secondary drying at various temperatures. Next, Figure 5 shows the relationship between the secondary drying temperature and methyl mercaptan content of dried seaweed that was stored after secondary drying at various temperatures. 172' of dried seaweed that was stored after secondary drying at the product temperature! jA is a diagram showing the relationship between product temperature and methyl mercaptan content. a... When stored with air for 12 months at 25°C b...2
When stored in N2 at 5℃ for 12 months C...12 at 10℃
When stored in air for 1 month d... When stored with N2 at 10℃ for 12 months e... Immediately after secondary drying (8733) Agent: Yoshiaki Inomata, Patent Attorney (Baka)
1 person) 2〉Shokuyo 1-Mizuichi JiC) Figure 1 Figure 2

Claims (4)

[Claims] (1) Dry raw seaweed at a temperature of 45°C or lower to adjust the moisture content to 8 to 16% by weight, then re-dry at a temperature of 45°C or lower to reduce the moisture content to 6% by weight or less. A method for preserving the quality of seaweed, which comprises adjusting the seaweed and storing it sealed in one or more inert gases or at a temperature of 20° C. or lower. (2) The method for preserving the quality of seaweed according to claim 1, wherein the re-dried seaweed is stored at a temperature of 15° C. or lower. (3) The method for preserving the quality of seaweed according to claim 2, wherein the re-dried seaweed is stored at a temperature of 10° C. or lower. (4) The method for preserving the quality of seaweed according to claim 1, wherein the re-dried seaweed is stored sealed in nitrogen gas.