JPH0218814B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an ice coating composition containing modified xanthan gum. When preserving fresh foods such as fish for a long period of time,
Oxidation and volatilization of food ingredients occur, and food during frozen storage tends to deteriorate. In order to prevent food deterioration during frozen storage, a method is used to cover the surface of the food to be frozen with a thin ice coating (glaze). It is desirable that the ice coating be thin and yet strong over a long period of time.
As a method for obtaining such an ice coating, various substances, especially xanthan gum, guar gum, locust bean gum, etc., are dissolved in ice coating water, the food to be frozen is soaked in the solution, and this is frozen, and then the surface of the food is coated. A method of forming an ice coat has been adopted. Xanthan gum is produced by xanthan gum-producing bacteria belonging to the genus Xanthomonas, such as
It is an extracellular polysaccharide produced by fermentation of Campestris. Xanthan gum has the property of being highly soluble in water and forming a viscous aqueous solution at low concentrations. This aqueous solution is stable even when left on ice, is not easily decomposed by enzymes, shows little change in viscosity even when the pH changes or changes in temperature, and exhibits high pseudoplasticity. . In this respect, xanthan gum is unique among conventional natural or processed gums. Therefore, xanthan gum is expected to have a wide range of uses as a thickener. In particular, xanthan gum has excellent freezing resistance, so it is used as an ice coating composition (Special Publication No. 56-22508
Publication No.). However, conventional xanthan gum has a drawback: in the presence of common salt, xanthan gum rapidly becomes difficult to dissolve in water. In general, seawater is often used as ice water because it is used at fishing ports, on ships, etc. Therefore, in addition to local gel-like substances remaining in the solution, insoluble residues such as fissures are generated. When these undissolved parts migrate to the ice coat, it weakens the ice coat and causes it to separate from the frozen object. Therefore, it was necessary to improve this point. The present invention was created in response to such a need. The present inventor has conducted extensive research in search of xanthan gum that easily dissolves in seawater and forms a homogeneous ice coat.
Rather than using conventional xanthan gum as it is, an attempt was made to modify the xanthan gum and change its viscous properties by subjecting it to appropriate physical treatments. As a result, it has been found that when the viscosity and fluidity index of xanthan gum reach specific values, the xanthan gum becomes extremely easy to dissolve in water for ice coating and exhibits appropriate viscosity at an early stage. For example, conventional xanthan gum is made into an aqueous solution, placed in a high-pressure homogenizer and subjected to shearing force, and then an organic solvent such as acetone or isopropyl alcohol is added to precipitate it, and the precipitate is separated and made into a powder. When this powder was taken out, it was confirmed that the viscosity and fluidity index of the powder were significantly different from those of the conventional powder. That is, based on a 0.5% xanthan gum aqueous solution dissolved at 25°C,
When measured using a type viscometer at a shear rate of 10 sec ^-1 , the viscosity of conventional xanthan gum is 260 CPS ~
It was confirmed that the xanthan gum modified as above has a viscosity of 50 CPS to 240 CPS and a fluidity index n of 1.25 to 2.50. The present inventor has also discovered that xanthan gum modified as described above easily dissolves transparently and quickly exhibits an appropriate viscosity even when it is added as a powder to water for ice coating. Ta. Furthermore, it was confirmed that the modified xanthan gum thus obtained had no adverse effect on the ice coating composition in other respects. This invention was made based on the above-mentioned knowledge and confirmation. It is known that xanthan gum can be specially treated and used in the production of foods (Japanese Unexamined Patent Publication No. 85256/1983). According to this publication, when conventional xanthan gum is added to a mixture of water and oil and subjected to high shear force to form an emulsion, the emulsion turns into a semi-gel or clubber, but when an aqueous solution of xanthan gum is passed through a homogenizer, The xanthan gum thus obtained will not semi-gel or clubber even when added to a mixture of water and oil and emulsionized under high shear force. That is, the above-mentioned publication is directed to foods to be emulsified by adding xanthan gum and then applying high shear force to the product. Therefore, the publication does not provide any teaching regarding the use of xanthan gum in ice coating compositions or regarding the viscous properties of xanthan gum. The present invention uses a 0.5% aqueous solution using an E-type viscometer,
The viscosity when measured at 25℃ at a shear rate of 10sec ^-1 is
This invention relates to an ice coating composition containing modified xanthan gum having a concentration of 50 CPS to 240 CPS. In the present invention, modification is performed by physical treatment. The physical treatment includes, for example, applying high shear force or ultrasonic treatment. During modification, xanthan gum is made into an aqueous solution. This aqueous solution may be a culture solution of a microorganism belonging to the genus Xanthomonas, or may be a powder obtained by purifying and drying this culture solution and dissolving it in water. The modified xanthan gum used in the present invention is
For example, 0.1 to 3% of conventional xanthan gum
An aqueous solution, preferably a 0.5 to 2% aqueous solution, is prepared using a pressure homogenizer (Manton-Gorlin model).
15M) of 50Kg/ ^cm2 or more, preferably 200
After passing through a homogenizer once or twice under a high pressure of ~600 Kg/cm ² , acetone is added thereto, a precipitate is taken out, and the precipitate is dried or pulverized if necessary. When using ultrasonic treatment, for example, use a Tomy Seiko model UR-200P, 200W ultrasonic processor,
It can be obtained by processing at 20 KHz and 0 to 4°C for an appropriate time. It can also be obtained by passing it through a colloid mill. Dissolve modified xanthan gum powder at 25℃.
When the viscosity of a 0.5% by weight aqueous solution is measured at 25℃ using an E-type viscometer at a shear rate of 10sec ^-1 , the value is
50CPS to 240CPS, and when the value of the fluidity index n is measured, the fluidity index n of this powder is
The value of is small, 1.25 to 2.50. Conventional xanthan gum has a viscosity of 260 CPS or more when it is a 0.5% by weight aqueous solution.
Moreover, the liquidity index n was 2.61 or more as mentioned above. Therefore, the modified xanthan gum is significantly different from the conventional one in terms of viscosity and the value of the fluidity index n. The fluidity index n mentioned here generally refers to the Herschel-Non-Newtonian fluid flow behavior of polymeric non-Newtonian fluids.
This is the index n used in Bukley's formula D=K(S-S ₀ ) ⁿ (Journal of Industrial Chemistry, Vol. 67, No. 10, 1964, P1624). This index n is
Simply put, it represents the distance from Newtonian flow, and the closer it is to 1, the closer it is to Newtonian flow. In the above formula, S is shear stress (dynes/cm ² ), S ₀ is yield value (dynes/cm ² ), K is viscosity constant, and D is shear rate (sec ⁻¹ ). The fluidity index n in this invention is determined by the shear rate measured using an E-type viscometer.
It is a value measured in the range of 2sec ^-1 to 100sec ^-1 . The modified xanthan gum used in the present invention can be used alone or in combination with locust bean gum and/or guar gum to prepare an ice coating solution in a conventional manner. That is, when forming an ice coating, a gummy substance is dissolved in seawater or fresh water to a concentration of 0.1 to 1.0%, preferably 0.5 to 0.8%, an ice coating solution is prepared, and a pre-frozen to-be-frozen solution is prepared. Dip objects into this ice-coating liquid and freeze them. When modified xanthan gum is used in combination with locust bean gum and/or guar gum, the blending ratio is 3 to 10 parts (preferably 4 to 6 parts) of modified xanthan gum to 3 to 10 parts (preferably 4 to 6 parts) of guar gum and locust bean gum. 1 to 5 parts (preferably 1 to 3 parts) of bean gum, or
0.3 to 0.5 parts of locust bean gum or 1 part of guar gum to 1 part of modified xanthan gum. Next, the process for obtaining the modified xanthan gum used in the present invention from conventional xanthan gum will be described below using experimental examples. While stirring the water from Experimental Example 1 and 2, 10 g of conventional xanthan gum was gradually added thereto, and stirring was continued for 30 minutes to dissolve the xanthan gum. This aqueous solution was then passed twice through a Manton-Gorlin homogenizer (model 15M) under a pressure of 400 Kg/cm ² . This permeate was concentrated under reduced pressure to one third of its volume, and then acetone was added so that the acetone content was 70% by volume, resulting in the precipitation of xanthan gum.
This precipitate was washed three times with acetone and dried under vacuum. The dried product was ground and adjusted to the same degree of powder as unmodified xanthan gum (80 mesh pass).
g of modified xanthan gum was obtained. Various physical properties of the thus obtained modified xanthan gum and unmodified xanthan gum were compared. The results are shown in Tables 1 to 8.

[Table] The viscosity η was determined by dissolving xanthan gum in distilled water at 25°C and measuring it as a 0.5% aqueous solution at each shear rate at 25°C using an E-type viscometer (manufactured by Tokyo Keiki Co., Ltd.). This is the value obtained. Intrinsic viscosity [η]
(ml/g) is gum solution concentration 0.005 to 0.015%
(contains 2% salt) using an E-type viscometer at a shear rate of 76.8 sec ^-1 and 25°C.

【table】

[Table] The values in Table 3 were measured at a shear rate of 10 sec ^-1 after a 0.5% aqueous solution dissolved at 25°C was left at room temperature. This shows that there is little change over time.

[Table] The above values are for an aqueous solution of 0.3% by weight of xanthan gum, which was heated at 120°C for 30 minutes.

[Table] The above values are the values obtained when 1% by weight of acetic acid and 2% by weight of common salt were added to a 0.3% by weight xanthan gum aqueous solution (PH 2.86) and then heated at 120°C for 30 minutes.

[Table] As the enzyme, cellulase from Nagase Sangyo Co., Ltd. was used and allowed to act at 37°C. The viscosity was measured using a B-type viscometer at 36 rpm and 37°C.

[Table] The mixing ratio of xanthan gum and locust bean gum was 1:1, and measurements were taken at 4°C.

[Table] Measured at 20℃. According to Table 1, modified xanthan gum has a lower viscosity, pseudoplasticity is closer to Newtonian flow, and lower apparent molecular weight than unmodified xanthan gum, and according to Table 2, the specific optical rotation is also different. Therefore, modified xanthan gum is considered to be different from unmodified xanthan gum. On the other hand,
According to Table 3, modified xanthan gum is stable over time like conventional xanthan gum, and Tables 4 to 6 show that the modified xanthan gum has thermal stability and
There is no change in salt tolerance, acid resistance, and enzyme resistance.
According to Tables 7 and 8, the synergy with galactomannan also has a tendency similar to that of conventional xanthan gum. In particular, when the modified xanthan gum is added to an aqueous solution containing common salt, it easily dissolves in the aqueous solution and produces a homogeneous solution free of precipitates and fisheyes. In this respect, modified xanthan gum is very different from conventional xanthan gum. Table 9 compares the solubility of modified xanthan gum and conventional xanthan gum in a saline solution.

[Table] The above values indicate an overall gum concentration of 0.4% by weight.
The viscosity was measured at 25℃ using a B-type viscometer.
The values measured at a rotation speed of 30 rpm are shown. The liquid/liquid mixture in the above table was obtained by mixing equal amounts of an aqueous solution with a gum concentration of 0.8% by weight and a saline solution of each concentration, and measuring the viscosity after standing overnight. Also,
For the powder mixture, 0.4% by weight of gum was added in powder form to an aqueous solution of each salt concentration, stirred at 25°C for 15 minutes, left overnight, and then the viscosity was measured. The viscosity development rate in the table above is the viscosity when mixing powders,
It is the value divided by the viscosity at the time of liquid mixing, expressed as a percentage. The larger the value of viscosity development rate,
Although it dissolves well, in the case of modified xanthan gum, the viscosity development rate is over 96%, whereas in the case of conventional xanthan gum, the viscosity development rate already drops to 38.2% at a salt concentration of 3%. and
This means that most of it is not dissolved. Experimental Example 2 Modified xanthan gums with various viscosities and fluidity indices were prepared by passing conventional xanthan gum through a Manton-Gorlin homogenizer (model 15M) and varying the pressure and number of treatments. Separately, conventional xanthan gum was subjected to ultrasound to prepare modified xanthan gums with various viscosities and fluidity indices. The modified xanthan gum powder obtained as described above was added at a ratio of 0.5% by weight to a 20% by weight saline solution, stirred at 25°C for 30 minutes, left overnight, and the viscosity of the solution was determined to be B-type viscosity. The viscosity was measured using a meter at 25° C. and a rotation speed of 30 rpm. The viscosity at that time and the number of fish eyes present per 2 cm square of the solution were measured.

【table】

[Table] In the above table, experiment number 1 is the case where conventional xanthan gum (unmodified) is used, experiment numbers 2 to 8 are the cases where modified xanthan gum prepared by a homogenizer is used, and experiment numbers 9 to 8 are the cases where modified xanthan gum prepared by a homogenizer is used.
No. 11 shows the case where a product with particularly low viscosity was made by ultrasonication and used. The viscosity of the aqueous solution in this table is calculated using E
The values were measured using a type viscometer at a shear rate of 10 sec ^-1 and 25°C, and the fluidity index n was the value for a 0.5% by weight aqueous solution. As can be seen from Table 10, those with a viscosity of 240 CPS or higher in a 0.5% aqueous solution do not dissolve sufficiently in a saline solution, and therefore exhibit low viscosity in an aqueous food solution, and many viscosity can be seen. , those with a viscosity of 240 CPS or less are completely dissolved and exhibit viscosity without forming a sticky eye. However, if the viscosity is less than 50 CPS, it will no longer exhibit a practical viscosity, which is undesirable. Furthermore, it is found from Experimental Example 3 below that the modified xanthan gum dissolves in seawater and does not produce local gels or insoluble residues. Experimental Example 3 When the solubility of modified xanthan gum and unmodified xanthan gum in seawater was tested, the following results were obtained. (Experimental method) 5 parts of gum were gradually added to 1000 parts of seawater using a stirrer, and after continued stirring for 5 minutes, the dissolved phase was observed.

[Table] Experimental Example 4 The ice coating adhesion rate and the evaporation amount, ie, the weight loss rate after 12 months of frozen storage, were tested for modified xanthan gum and unmodified xanthan gum. Add 50 g of modified xanthan gum powder to 6,200 g of seawater and stir by hand using an appropriate stirring rod for 3 minutes to obtain a liquid for ice coating. No undissolved portion of the modified xanthan gum powder was observed, and a uniform ice coating solution was obtained. In addition, a seawater solution of unmodified xanthan gum powder was prepared in the same manner. Although undissolved gum powder was found in the seawater solution of unmodified xanthan gum, it was used as is in the experiment as an ice coating solution. Meanwhile, prepare 20 frozen squid of known weight,
Divide into two groups of 10 animals each. One group is immersed in a modified xanthan gum seawater solution, and the remaining group is immersed in an unmodified xanthan gum seawater solution for 5 seconds each. Immediately after immersion, freeze at -20°C, and measure the weight of each group immediately after freezing and after 12 months of frozen storage at -20°C. The ice coating adhesion rate and weight loss rate of the frozen product after 12 months of frozen storage were measured as follows. Ice coating adhesion rate = A'-A/A x 100 (%) A: Weight of frozen fish before immersion in ice-coating solution A': Weight of frozen fish after immersion in ice-coating solution Weight loss rate after 12 months of frozen storage = B-B '/B x 100 (%) B: Fish weight immediately after freezing after immersion in ice coating liquid B': Experimental results of fish weight after 12 months of frozen storage after immersion in ice coating liquid

[Table] From the above experiments, the amount of ice coating of modified xanthan gum and the weight loss rate after 12 months of frozen storage are better than that of unmodified xanthan gum, so modified xanthan gum is effective in protecting fish bodies during frozen storage. It can be assumed that there is. The present invention will be explained below based on Examples. Example 1 An ice coating liquid was prepared by adding and dissolving 5 parts of modified xanthan gum in 1000 parts of seawater to obtain an ice coating liquid containing no fisheye. Tuna is immersed in this ice-coating solution, taken out, and frozen.
The ice coat did not peel off for 12 months and retained its quality for a long time. Example 2 8 parts of an ice coating composition consisting of 5 parts of modified xanthan gum, 5 parts of guar gum, and 1 part of locust bean gum was dissolved in 1000 parts of seawater. The ice coating solution contained no insoluble residue and was homogeneous. The tuna was immersed in the ice coating liquid, taken out, and the fish body was frozen. This ice coating did not peel off for 12 months and maintained the quality of the frozen product. Example 3 The same procedure as in Example 2 was carried out using unmodified xanthan gum instead of modified xanthan gum. The ice coating solution contained a large amount of ice cream and was locally gelled. The ice coat was easily peeled off.

Claims (1)

[Claims] 1 Measure the shear rate of a 0.5% aqueous solution using an E-type viscometer.
An ice coating composition comprising modified xanthan gum having a viscosity of 50 CPS to 240 CPS when measured at 10 sec ^-1 at 25°C.