JP2000157225A - Agar-agar - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an agar-agar realizing a low jelly strength without cleaving molecules and having both an excellent viscosity and an excellent water-holding capacity. SOLUTION: This agar-agar has a stress of >=20,000 Pa at a share rate of 0.005 (1/s) and at a deformation of 20% in rheology characteristics in the compression mode of the agar-agar gel, and further has a stress relaxation time of >=8 sec until an inner stress becomes a half of an initial stress.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to agar having low jelly strength and excellent water retention and viscosity.

[0002]

2. Description of the Related Art Agar is extracted from seaweeds of red algae, such as Ogonori, Amakusa and Oberusa, by hot water, filtered, gelled, and so on.
It is dried through a dehydration and drying process. The main components of agar are agarose and agaropectin, of which agarose plays a major role in gelling power (concept including gel-forming ability and jelly strength). That is, the ratio of agarose to agaropectin is one factor that determines the gelling power. Therefore, it has been known that agaropectin should be removed when a large gelling power is desired. Usually, in order to produce agar having a large gelling power, the raw material seaweed is subjected to alkali treatment prior to the extraction step with hot water. By this alkali treatment, deesterification occurs as shown in FIG.
Anhydro-L-galactose is formed. As a result, the ratio of the agarose component increases, and this increases the gelling power.

[0003] Another factor that determines the gelling power of agar is the molecular weight. In the production of agar, molecules are generally cut by the addition of an acid to obtain agar having a desired gelling power, including the purpose of facilitating extraction.
Furthermore, when it is desired to obtain agar with lower jelly strength (hereinafter referred to as low-strength agar) in foods and other uses, a considerable amount of acid treatment is performed during hot water extraction or thereafter at an appropriate stage to cut agar molecules. Has already been proposed by the present applicant (Japanese Patent Application No. 4-1488).
No. 55). In addition, it is known that, if an acid treatment is not performed and extraction is performed without cutting molecules, a high strength and a high melting point are obtained (Japanese Patent No. 2560027).

[0004]

However, alkali treatment is carried out at the stage of raw seaweed, and agar is generally used for hot water extraction by adding an acid. The low-strength agar obtained by this method has a low molecular weight, and therefore has insufficient viscosity for some applications, is brittle, and does not have a large water retention capacity. Therefore, an object of the present invention is to provide an agar that achieves low jelly strength without breaking molecules and has both excellent viscosity and water retention ability.

[0005]

The agar according to the present invention comprises:
In the rheological properties of the agar gel in the compression mode, the stress relaxation time until the stress at a shear rate of 0.005 (1 / s) at 20% deformation is 20,000 Pa or more and the stress becomes half of the initial stress Is 8 seconds or more.

The agar according to the present invention is also characterized in that, in the rheological characteristics of the agar gel in the compression mode, the stress after 20 seconds is at least 1/3 of the initial stress in the stress relaxation measurement when a 20% deformation stress is applied. It is characterized by.

[0007] Such agar has, for example, a sulfate content of 1%.
The agar component is extracted and filtered by treating 10% of the raw seaweed with neutral hot water to extract and filter the agar component. The gel has a jelly strength of 600 g / cm ² or less (more preferably, 400 g / cm ² or less), and
It satisfies at least one of (a) a sol having a 1.5% agar concentration having a viscosity of 15 cp or more at 85 ° C., and (b) an average molecular weight in a range of 400,000 to 2,000,000. However, in practice, the gel with a 1.5% agar concentration has a jelly strength of 10 g / cm ² or more,
The viscosity at 85 ° C. of the 1.5% agar sol is preferably 200 cp or less.

The agar according to the present invention is obtained, for example, by subjecting a raw seaweed to an alkali treatment whose degree is adjusted in accordance with the sulfate content thereof, and then sufficiently removing the alkali by washing with water, and then using hot water near neutrality. The agar component can be produced by extraction filtration, gelation, dehydration and drying.
Further, the alkali treatment is performed using a treatment solution selected from caustic soda, caustic potash, slaked lime, quick lime, and ammonium hydroxide at a treatment solution concentration of 0.1 to 10.0% and a treatment temperature of 0%.
The processing degree may be adjusted within a range of from 100 ° C. to a processing time of from 1 to 180 minutes.

The present invention is based on the findings of the present inventors that there is a certain correlation between the content of sulfate groups contained in the raw seaweed and the degree of alkali treatment of the raw seaweed, and the gelling power. . FIG. 2 conceptually shows the correlation. That is, although the raw material seaweed has a different sulfate content depending on the type, the gelling power increases as the content decreases (that is, as the agarose content increases), and the gelling power increases as the molecular weight increases. Further, when these two factors are combined, a larger gelling force is obtained as shown in FIG.
On the other hand, since the sulfate is desulfated by the alkali treatment as shown in FIG. 1, the sulfate content is, as shown in FIG.
It will be inversely proportional to the degree of alkali treatment. Therefore, when the degree of alkali treatment is high, the gelling power is increased.

As a result of further experiments based on the above findings, it was found that, in the case of a raw seaweed having a sulfate content of 1 to 10%, the raw seaweed was not subjected to alkali treatment and was not subjected to acid treatment after extraction. Extraction with neutral hot water, the rheological properties of the agar gel in the compression mode, the stress at 20% deformation at a shear rate of 0.005 (1 / s) is 20,000 Pa or more, and the stress relaxation time In the agar in which the time until becomes half of the initial stress is 8 seconds or more, and the rheological properties in the compression mode of the agar gel,
The stress relaxation measurement when 20% deformation stress was applied revealed that agar with a stress after 20 seconds that was 1/3 or more of the initial stress could be obtained. When alkali treatment or acid treatment is performed,
As a result of desulfurization by alkali treatment and molecular cleavage by acid treatment, the agar gel becomes cloudy and has low transparency, but if neither alkali treatment nor acid treatment is performed, a transparent gel is obtained.

Further, as can be understood from FIGS. 2 and 3, after the raw seaweed is subjected to an alkali treatment whose degree is adjusted in accordance with its sulfate content, the agar component is further neutralized with hot water. By extracting and filtering, agar having a constant gelling power can be obtained regardless of the type of raw material seaweed.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 4 shows an agar production process according to an embodiment of the present invention. As shown in the figure, the raw seaweed is first treated with an alkali, if necessary. The degree of the alkali treatment is determined by the sulfate content of the raw seaweed, the details of which will be described later. After that, extraction with neutral hot water is performed, followed by filtration, gelation, freeze-drying, and drying steps according to the usual steps to produce dry agar.

The degree of the alkali treatment is adjusted by the type and concentration of the alkaline aqueous solution used, the treatment temperature and the treatment time. Specifically, FIG. 5 shows changes in the sulfate content of seaweeds (Ogonori C and Amakusa C) when the treatment temperature was fixed at 50 ° C. and the treatment time was a factor, and the degree of alkali treatment was changed. is there. FIG. 6 shows that the processing time is 6
It is the same data when the degree of alkali treatment is changed with the treatment temperature as a factor, which is fixed at 0 minutes. When the sulfate content of the raw material is 4 or less, a product having a jelly strength of 200 g / cm ² or more and a sol viscosity of 15 cp or more can be obtained without alkali treatment of seaweed.

Actually, Amakusa A (from South Africa), Amakusa B (from Chile), Ogonori A (from Argentina), and Ogonori B (from Chile) as raw seaweed are not subjected to alkali treatment according to the flow of FIG. Table 1 shows the physical properties of the agar obtained when the agar was subjected to the alkali treatment (40 ° C., 1 hour and 80 ° C., 1 hour).

[0015]

[Table 1]

From Table 1, Amakusa A is untreated, Amakusa B is untreated and treated at 40 ° C., and Ogonori A is untreated and treated at 40 ° C.
In the treatment, the target properties of each of Ogonori B are obtained at 40 ° C. In the case of the examples, the physical properties change under each condition, and in order to obtain the target physical properties, the degree of alkali treatment is changed depending on the content of the sulfate group of the seaweed, and the molecule is further cut by extracting near neutrality. This can be achieved by increasing the molecular weight without any increase. As a result, 1.
The jelly strength is 600 g / cm ² or less at 5% agar concentration, and the physical properties of the sol having a viscosity of 15 cp or more at 85 ° C. are obtained.

Table 2 shows that Amakusa C (Mediterranean) and Ogonori C (Brazil) were untreated, as in Table 1.
After the alkali treatment at 40 ° C. for 1 hour, the extract was extracted with neutral hot water, the extract was extracted with alkali treatment under the condition of a conventional commercially available agar, and the same jelly strength was obtained. This is a comparison of the molecular weight and the sol viscosity of agar with a reduced extraction pH.

[0018]

[Table 2]

As is apparent from Table 2, the agar according to the present invention has a large molecular weight and a high sol viscosity, despite the same jelly strength as the conventional agar. Further, as shown in Table 1, it was confirmed that the agar according to the present invention was lower in the amount of syneresis as compared with those having a jelly strength of 600 g / cm ² or more, and was excellent in water retention. Further, agar (a) obtained by treating Amakusa C at 40 ° C. for 1 hour and neutral extraction, and treating at 80 ° C. for 1 hour, pH 6
The agar (b) obtained by the extraction described above was adjusted to a gel having a thickness of 1 mm at a concentration of 1.5% agar and RSA manufactured by Rheometrics Co., Ltd.
2 and a parallel plate having a diameter of 4.75 mmφ, in the compression mode, (1) share rate (Sharer).
ate) Stress at 20% deformation when stress-strain measurement is performed at 0.005 (1 / s), and (2) Time until stress is reduced from 20% deformation state and initial stress is reduced to half. And were measured. Table 3 shows the results.

[0020]

[Table 3] Time until the stress is reduced by half Stress at the time of 20% deformation (a) 10.3 sec 24,600 Pa (b) 5.25 sec 16,500 Pa

Similarly, Table 4 shows the results of a similar test conducted on a conventional commercially available agar (trade name (Ina agar) manufactured by Ina Food Industry Co., Ltd.).

[0022]

Table 4 Time until the stress is reduced by half Stress at the time of 20% deformation Ina agar M-7 4.25 sec 17,800 Pa Ina agar S-9 5.25 sec 18,700 Pa Ina agar UM-11 1.25 sec 9,880 Pa Ina agar UP-37 5.25 sec 17,700 Pa Ina agar KT 6.75 sec 19,400 Pa

Table 5 below shows changes in stress (unit: gmf) with respect to the stress relaxation time (horizontal is sec) in the stress relaxation measurement when a 20% deformation stress is applied.

[0024]

[Table 5]

As is clear from Tables 3 and 4, the agar according to the present invention [Table 3 (a)] has a stress at 20% deformation of 2%.
It can be seen that the rheological properties of the two agars are significantly different from those of the conventional agar [Table 3 (b), Table 4], which is less than 20,000 Pa. As is clear from Table 5, in the agar according to the present invention, the stress after 20 seconds was 1/3 or more of the initial stress in the stress relaxation measurement when a 20% deformation stress was applied. Was less than / 3. Therefore, this agar has a new property in which the gel is sticky and imparts a rubber-like property to the fragility of the conventional agar, and its extensibility and handleability are improved, and it has many potential applications. are doing.

FIG. 7 summarizes the relationship between the jelly strength and the molecular weight obtained for various agars extracted from more seaweeds. From FIG. 7, the specificity of the agar according to the present invention, which has low jelly strength and excellent viscosity and water retention, can be understood.

[0027]

As described above, according to the present invention, it is possible to obtain an agar having a large difference in rheological characteristics from the conventional agar, a low jelly strength, and an excellent viscosity and water retention.

[Brief description of the drawings]

FIG. 1 is a diagram showing deesterification of agar by alkali treatment.

FIG. 2 is a graph showing the relationship between the sulfate content of raw seaweed and the gelling power.

FIG. 3 is a graph showing the relationship between the degree of alkali treatment and the content of sulfate groups.

FIG. 4 is a diagram showing processing steps of an example.

FIG. 5 is data showing the relationship between alkali treatment time and sulfate content.

FIG. 6 is data showing the relationship between alkali treatment temperature and sulfate content.

FIG. 7 shows the relationship between jelly strength and molecular weight of various agars.

Continued on the front page (72) Inventor Yuji Utsuhashi 5074 Nishiharuka, Ina-shi, Nagano F-term (reference) in Ina Food Industry Co., Ltd. 4B019 LK05 LP02 LP05 LP08 LP09 LP13

Claims (2)

[Claims] The rheological characteristics of the agar gel in the compression mode are as follows.
agar, wherein the stress at 20% deformation in s) is 20,000 Pa or more, and the stress relaxation time until the stress becomes half of the initial stress is 8 seconds or more. 2. The agar characterized in that in the compression mode of the agar gel, the stress after 20 seconds is at least 1/3 of the initial stress in a stress relaxation measurement when a 20% deformation stress is applied.