Manufacturing method of nata de coco sheet

Abstract

Provided is a new method for producing a Nata de Coco sheet that can suppress the formation of irregularities on the surface of the Nata de Coco sheet. A method for producing a nata de coco sheet comprising the following steps (A) and (B). (A) A seed culture step in which a seed medium containing acetic acid bacteria having cellulose-producing ability is used to carry out agitation culture with an agitation power requirement per unit volume of 8.0 W or more. (B) A main culture step in which a portion of the seed medium obtained in the step (A) is inoculated into a main culture medium and static culture is performed.

Description

[Technical Field]

[0001] The present invention relates to a method for producing a Nata de Coco sheet. In particular, the present invention relates to a method for producing a Nata de Coco sheet, which includes a seed culture step and a main culture step of inoculating a part of the seed medium obtained by the seed culture step into a main culture medium and performing static culture. [Background technology]

[0002] Nata de coco is a traditional fermented food originating in the Philippines. It is a biocellulose produced by fermenting coconut milk or coconut water using cellulose-producing acetic acid bacteria. Nata de coco is a low-calorie food rich in dietary fiber and is widely used in diet foods and foods for specified health uses. In recent years, its excellent water-retaining properties due to its reticular structure have led to its widespread use in cosmetics, such as face masks (face sheets) impregnated with beauty serums.

[0003] The method for producing such Nata de Coco typically involves static culture (flat plate culture) in a tray. When acetic acid bacteria are inoculated into the main medium in the tray, a cellulose film forms on the liquid surface of the static medium as the bacteria grow. Thereafter, cellulose is continuously produced near the liquid surface, and the cellulose film gradually increases in thickness. After about 10 days, a sheet-like Nata de Coco having a thickness of about 15 to 20 mm (hereinafter, the sheet-like Nata de Coco will be referred to as a "Nata de Coco sheet") is obtained.

[0004] In this regard, acetic acid bacteria are aerobic bacteria, and during static culture, bacterial growth occurs near the liquid surface. Therefore, in order to mass-cultivate acetic acid bacteria, for example, it is necessary to increase the surface area of ​​the culture medium (i.e., the tray area), which poses a problem in production efficiency.

[0005] In addition, since static culture is not a completely sealed culture, the probability of microbial contamination from the air increases as the surface area of ​​the culture medium (i.e., the tray area) increases. For example, if microbial contamination occurs in the seed culture process, microbial contamination will occur in all main culture media inoculated with the contaminated seed medium. Therefore, preventing microbial contamination is an important issue in the method for producing nata de coco sheets.

[0006] In response to this problem, the present applicant has already proposed a method for producing nata de coco sheets that combines a seed culture process in which seed culture is performed by shaking culture and a main culture process in which a portion of the seed medium obtained by the shaking culture is inoculated into a main medium and static culture is performed (Patent Document 1).

[0007] According to the method for producing Nata de Coco sheets described in Patent Document 1, the bacterial cell concentration at the end of the seed culture process can be significantly increased compared to conventional static culture. In addition, in conventional static culture, the bacterial cell concentration is about 20 m per 1,000 L of seed medium. 2 However, according to the method for producing Nata de Coco sheets described in Patent Document 1, for example, one culture tank with a capacity of 1,000 L is sufficient, which reduces the risk of microbial contamination in the seed culture process. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-11818 Summary of the Invention [Problem to be solved by the invention]

[0009] However, as described in Patent Document 1, when shaking culture (reciprocating shaking culture) is performed at a shaking speed of 125 rpm in the seed culture step, large cellulose lumps with a major axis diameter of 150 μm or more are generated in the culture solution, and when these cellulose lumps are mixed into the main medium, the surface of the obtained Nata de Coco sheet (in the Nata de Coco sheet (N) shown in FIG. 7, the surface (N) facing the bottom side of the tray (T) containing the culture solution (C)) becomes dirty. S )) results in large irregularities (see Patent Document 1, Figure 5(b)). In the production method described in Patent Document 1, in order to suppress the formation of such irregularities, it is necessary to interpose a filtration step between the seed culture step and the main culture step to remove cellulose aggregates with a major axis diameter of 150 μm or more. It is also envisioned that, instead of the filtration step, a slicing step can be carried out using a cutter or the like to remove the irregularities. The manufacturing method and the method of performing the slicing process described in Patent Document 1 have concerns about increased manufacturing costs due to increased man-hours and reduced yields, and the slicing process also has concerns about increased waste of cut pieces, so there is still room for improvement. Therefore, it is desirable to develop a culture method that does not generate cellulose lumps with a major axis diameter of 150 μm or more in the culture solution during the seed culture process.

[0010] On the other hand, the surface of the Nata de Coco sheet obtained by conventional static culture using a medium containing coconut milk as a raw material (surface (N S )) forms a milky white thin film containing coconut milk components, also known as a milk film. The milk film not only poses the risk of being perceived as a foreign substance contamination and impairs the aesthetic appearance of the product, but also adversely affects, for example, the texture (crispness), so the milk film is usually peeled off from the Nata de Coco sheet obtained by static culture. However, this work is performed manually using tools such as spatulas, which not only increases production costs, but also makes the peeling process even more labor-intensive if the milk film is firmly formed on the surface of the Nata de Coco sheet. There is also concern that some of the milk film may remain on the Nata de Coco sheet even after the peeling process. Therefore, in order to reduce manufacturing costs by reducing the number of steps, it is necessary to develop a method that can easily peel off and remove the milk film.

[0011] The present invention has been made against the background of the above circumstances, and in a method for producing a Nata de Coco sheet, it is possible to suppress the generation of cellulose lumps having a major axis diameter of 150 μm or more in the culture solution in the seed culture step, and in particular, it is possible to suppress the generation of cellulose lumps having a major axis diameter of 50 μm or more, and to provide a new method that can suppress the formation of unevenness on the surface of the Nata de Coco sheet.

[0012] Furthermore, one embodiment of the present invention further provides a new method for easily peeling and removing the milk film. [Means for solving the problem]

[0013] In view of the above circumstances, the present inventor has conducted extensive research and has found that in a method for producing Nata de Coco sheets, which includes a seed culture step of performing seed culture by stirring culture and a main culture step of inoculating a main culture medium with a portion of the seed culture medium obtained in the seed culture step and performing static culture, the stirring power required per unit volume (P V ) within a specific range, it is possible to suppress the generation of cellulose lumps with a major axis diameter of 150 μm or more in the seed culture process, particularly the generation of cellulose lumps with a major axis diameter of 50 μm or more. It has been found that this can suppress the formation of unevenness on the surface of the nata de coco sheet.

[0014] That is, the present invention provides the following [1] to [5]. [1] A method for producing a nata de coco sheet comprising the following steps (A) and (B). (A) A seed culture step in which a seed medium containing acetic acid bacteria having cellulose-producing ability is used to carry out agitation culture with an agitation power requirement per unit volume of 8.0 W or more. (B) A main culture step in which a portion of the seed medium obtained in the step (A) is inoculated into a main culture medium and static culture is performed. [2] The method for producing a nata de coco sheet according to [1], wherein the stirring power required in the step (A) is 9.0 W or more and 3,000 W or less. [3] The method for producing a Nata de Coco sheet according to [1] or [2], wherein the average particle diameter of the cellulose lumps contained in the seed medium obtained by the step (A) is 50 μm or less. [4] The method for producing a nata de coco sheet according to [1] or [2], wherein the average particle diameter of the cellulose lumps contained in the seed medium obtained by the step (A) is less than 30 μm. [5] The method for producing a nata de coco sheet according to any one of [1] to [4], wherein the main medium in the step (B) is a main medium containing coconut milk. [Effects of the Invention]

[0015] According to the method for producing a Nata de Coco sheet of the present invention, the formation of unevenness on the surface of the Nata de Coco sheet can be suppressed.

[0016] In one embodiment of the method for producing a Nata de Coco sheet of the present invention, the milk film can be easily peeled off and removed. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a photograph of the Nata de Coco sheet of Reference Example 1. [Figure 2] 1 is a photograph of the Nata de Coco sheet of Comparative Example 1. [Figure 3] 1 is a photograph of a Nata de Coco sheet according to Example 2 of the present invention. [Figure 4] 1 is a photograph of a Nata de Coco sheet according to Example 3 of the present invention. [Figure 5] 1 is a photograph of the Nata de Coco sheet of Example 7 of the present invention. [Figure 6] 1 is a photograph of the Nata de Coco sheet of Example 9 of the present invention. [Figure 7] FIG. 1 is a schematic cross-sectional view illustrating a Nata de Coco sheet obtained after static culture using a tray. DETAILED DESCRIPTION OF THE INVENTION

[0018] The present invention will be described below based on examples of embodiments for carrying out the present invention, but the present invention is not limited to the embodiments described below.

[0019] As used herein, "main culture" means the final stage of culture in which the obtained Nata de Coco sheet is used as a raw material for product production after the completion of the culture. "Seed culture" is a culture other than the main culture that is carried out before the main culture, for example, a culture before being transferred to the main culture, which is a larger-scale culture.

[0020] Furthermore, in this specification, when the expression "X to Y" (X and Y are any numbers) is used, unless otherwise specified, it means "X or more and Y or less," as well as "preferably larger than X" or "preferably smaller than Y." Furthermore, in this specification, when it is expressed as "X or more" (X is any number) or "Y or less" (Y is any number), it also means that "it is preferably greater than X" or "it is preferably less than Y."

[0021] The method for producing a Nata de Coco sheet according to one embodiment of the present invention (hereinafter sometimes referred to as "this production method") is characterized by including steps (A) and (B). (A) A seed culture step in which a seed medium containing acetic acid bacteria having cellulose-producing ability is used to carry out agitation culture with an agitation power requirement per unit volume of 8.0 W or more. (B) A main culture step in which a portion of the seed medium obtained in the step (A) is inoculated into a main culture medium and static culture is performed.

[0022] This production method includes (A) a seed culture step and (B) a main culture step, and in (A) the seed culture step, stirring culture is performed using a stirring blade. In this production method, the stirring power required per unit volume (liquid volume) in (A) the seed culture step (P VIt is important to perform agitation culture with a power requirement of 8.0 W (watts) or more. V ) to 8.0 W or more, it is possible to suppress the generation of cellulose lumps having a major axis diameter of 150 μm or more (particularly a major axis diameter of 50 μm or more), and the formation of irregularities on the surface of the Nata de Coco sheet can be suppressed. It is possible to easily peel off and remove the milk film.

[0023] The required stirring power (P V Although the reason why the above-mentioned excellent effect is achieved by setting the shear force of the stirring blade to a value equal to or greater than the above-mentioned predetermined value is not entirely clear, the inventors' considerations suggest that by making the cellulose lumps smaller than the conditions described in Patent Document 1 (removing cellulose lumps with a major axis diameter of 150 μm or more) due to the shear force of the stirring blade, the formation of cellulose lumps with a major axis diameter of 50 μm or more in the seed culture process is suppressed, for example, and the incorporation of cellulose lumps with a major axis diameter of 50 μm or more into the main medium is effectively prevented, thereby suppressing the formation of unevenness on the surface of the nata de coco sheet. Furthermore, it is speculated that the cellulose lumps having a major axis diameter of 50 μm or less and the shear strength of the stirring blade reduce the crystallinity of the cellulose and increase the amorphous portion, thereby making it possible to easily peel off and remove the milk film.

[0024] According to this manufacturing method, the degree of unevenness on the surface of the Nata de Coco sheet can be reduced, for example, the filtration process and slicing process as described above can be eliminated. Furthermore, according to this manufacturing method, the labor required to peel off the milk film can be reduced, for example, the process of peeling off the milk film can be almost eliminated. Therefore, according to this manufacturing method, compared to conventional manufacturing methods, it is possible to reduce the number of steps, improve yield, and reduce waste. It is extremely useful in that it can.

[0025] Steps (A) and (B) of this production method will be explained in more detail below.

[0026] <(A) Process> Step (A) is a step of inoculating a seed medium with acetic acid bacteria capable of producing cellulose, and carrying out agitation culture using a culture device equipped with an agitator blade.

[0027] Examples of acetic acid bacteria capable of producing cellulose include, but are not limited to, species of the genus Acetobacter, such as Acetobacter xylinum and Acetobacter pasteurianus, and species of the genus Gluconacetobacter, such as Gluconacetobacter xylinus.

[0028] The seed culture medium in the seed culture step can be made of conventional ingredients used in culturing Nata de Coco. For example, coconut milk, coconut water, carbon sources, nitrogen sources, mineral sources, pH adjusters, etc. can be used as appropriate, but are not limited to these. Specifically, for example, a liquid medium can be prepared by appropriately blending carbon sources such as sugars such as fructose, glucose, galactose, and sucrose, nitrogen sources such as yeast extract and soybean hydrolysate, mineral sources such as phosphates, magnesium salts, and calcium salts, and medium components such as ethanol, and adjusting the pH by adding a pH adjuster such as sodium hydroxide solution.

[0029] The pH of the seed medium is adjusted appropriately depending on the bacterial species, but can usually be adjusted appropriately within the range of pH 2.5 to 7. When increasing the number of bacteria in a short period of time, a pH of 4.5 to 7 is preferable. 6 When a concentration of about cells / mL is acceptable, the pH of the seed medium may be in the range of 2.5 to 7. From the viewpoint of suppressing microbial contamination, it is preferable to appropriately adjust the pH to within the range of 2.5 to 4.5.

[0030] (Culture equipment) The culture apparatus may be a conventional culture apparatus equipped with agitating blades. Specifically, for example, a culture apparatus having a culture tank and an agitating blade attached to a vertically extending shaft or a fixed shaft that can be rotated by a drive source such as a motor is used. A baffle plate may be installed inside the culture tank.

[0031] Examples of stirring blades that can be used include, but are not limited to, paddle blades, pitched paddle blades, screw blades, propeller blades, anchor blades, turbine blades, etc. The number of stirring blade stages is, but is not limited to, typically about 1 to 5 stages. The number of blades is, but is not limited to, typically about 2 to 6 blades per stage.

[0032] (agitated culture) As mentioned above, this production method is clearly different from the static culture in conventional Nata de Coco sheet production methods and the shake culture in which the culture vessel is shaken (reciprocating shake culture, gyratory shake culture) in that acetic acid bacteria having cellulose-producing ability are inoculated into a seed medium and agitation culture is performed using a culture device equipped with an agitator blade. Furthermore, this production method suppresses the formation of irregularities on the surface of the Nata de Coco sheet and, from the viewpoint of easily peeling and removing the milk film, reduces the required agitation power (P per unit volume (liquid volume)) in the seed culture step. V ) to 8.0W (watts) or more.

[0033] The required stirring power (P V The stirring power (P) is preferably 8.0 to 10,000 W, more preferably 8.5 to 5,000 W, even more preferably 9.0 to 3,000 W, and even more preferably 9.7 to 2,800 W. V By controlling the stirring power (P) within the above range, it is possible to suppress the formation of irregularities on the surface of the Nata de Coco sheet and to enhance the effect of easily peeling and removing the milk film. V If the stirring power (P) is too low, it tends to be difficult to suppress the formation of irregularities on the surface of the Nata de Coco sheet, and it tends to be difficult to easily peel off and remove the milk film. VIf the value of ) is too high, the effect of suppressing the formation of surface irregularities tends to be reduced.

[0034] The required stirring power (P V ) can be set appropriately within the above range, but from the viewpoint of more effectively suppressing the formation of unevenness on the surface of the Nata de Coco sheet, for example, 8.0 to 55 W is preferable, and more preferably 9.0 to 30 W. It can also be about.

[0035] The required stirring power (P V :W / m 3 ) is the unit volume (liquid volume) (m 3 ) is used as an index of the degree of stirring in chemical engineering, and can be determined by a known method. V ) can be calculated using the following formula (1): [Formula] Mixing power required (P V )=P / V=Np×ρ×n 3 ×d 5 / V ···(1) P: Mixing power required [W] V:Liquid capacity [m 3 ] Np: Power number ρ: Liquid density [kg / m 3 ] n: Rotation speed of the stirring blade [rps] d: stirring blade diameter [m]

[0036] The "Np: power number" is calculated, for example, based on Table 3 in "Importance of mixing power requirements in the design and operation of mixing vessels" (Collection of Chemical Engineering Papers, Vol. 35, No. 2, pp. 211-215, 2009).

[0037] In this production method, the liquid volume (V) (liquid volume of the seed medium containing acetic acid bacteria) contained in the culture tank is, but is not limited to, 0.0001 to 10 m 3 It is preferable to set the thickness in the range of 0.01 to 5 m. 3 , more preferably 0.1 to 1 m3 is. In the present production method, the liquid density (ρ) in the culture tank (the liquid density of the seed medium containing acetic acid bacteria at 30°C) is not limited to the following, but is usually 1,000 to 1,225 kg / m 3 From the viewpoint of the culture rate and assimilation efficiency, it is preferably 1,000 to 1,123 kg / m 3 , more preferably 1,000 to 1,078 kg / m 3 is.

[0038] In this production method, the rotation speed (n) of the stirring blade is preferably 125 to 2,000 rpm, more preferably 140 to 1,500 rpm, and even more preferably 150 to 1,200 rpm, when the liquid volume is 0.1 to 1.0 L, from the viewpoint of suppressing the formation of irregularities on the surface of the Nata de Coco sheet and enhancing the effect of easily peeling and removing the milk film.

[0039] Furthermore, in the present production method, the ratio (d / D) of the impeller diameter (d) of the stirring impeller to the vessel diameter (D) of the culture vessel is not limited to the following, but is usually 0.1 to 1. From the viewpoints of uniform stirring and damage to acetic acid bacteria, it is preferably 0.2 to 0.8, more preferably 0.3 to 0.7.

[0040] In this production method, the ratio (H / D) of the liquid level height (H) of the culture medium to the vessel diameter (D) of the culture vessel is not limited to the following, but is usually 0.5 to 2.0, and from the viewpoint of uniform stirring, is preferably 1.0 to 1.5.

[0041] The temperature condition for step (A) is usually 20 to 40°C, preferably 25 to 35°C.

[0042] The culture time in step (A) is usually 24 to 96 hours, and from the viewpoint of production efficiency, it is preferably 24 to 72 hours, more preferably 24 to 48 hours.

[0043] The viable cell count [CFU / g] at the end of the seed culture in step (A) is usually, but not limited to, 1.0 x 10 3 ~1.0×109 CFU / g, and from the viewpoint of production efficiency, preferably 1.0 × 10 5 ~1.0×10 9 CFU / g, more preferably 1.0 × 10 6 ~1.0×10 9 CFU / g.

[0044] The average particle size of the cellulose mass contained in the seed medium after completion of the seed culture in step (A) is preferably 50 μm or less, more preferably less than 30 μm, even more preferably less than 25 μm, and particularly preferably less than 15 μm, from the viewpoint of suppressing the formation of irregularities on the surface of the Nata de Coco sheet. The average particle size can be measured by the method described in the examples below.

[0045] <(B) Process> Step (B) is a main culture step in which a portion of the seed medium obtained by the seed culture step (A) is inoculated into the main medium poured into the tray to perform static culture, and is a step for obtaining a nata de coco sheet.

[0046] The medium used in step (B) can be a liquid medium containing various conventionally used ingredients such as coconut milk, coconut water, and various medium components, similar to the seed medium used in step (A).

[0047] In step (B), the amount of seed medium to be inoculated into the main medium depends on the bacterial concentration of the seed medium. For example, 6 For CFU / g, approximately 1 / 100 to 10 / 100 of the volume of the medium is appropriate.

[0048] In step (B), the pH of the medium is adjusted appropriately depending on the bacterial species, but can usually be adjusted appropriately within the range of pH 2.5 to 7. From the viewpoint of suppressing microbial contamination, it is preferable to adjust the pH appropriately within the range of pH 2.5 to 4.5.

[0049] The temperature conditions in step (B) are, for example, preferably 20 to 40°C, more preferably 25 to 35°C.

[0050] The culture time in step (B) is, for example, 4 to 20 days. From the viewpoint of the thickness of the Nata de Coco sheet and production efficiency, it is preferable to appropriately adjust the culture time within the range of 4 to 14 days.

[0051] <Nata de Coco Sheet> The size of the Nata de Coco sheet obtained by this production method is not limited to the following, but for example, from the viewpoint of ease of handling, a length of 10 to 100 cm, a width of 10 to 100 cm, and a thickness of 2 to 30 mm is preferable. For food use, a length of 0.5 to 75 cm, a width of 0.5 to 50 cm, and a thickness of 5 to 20 mm is preferable.

[0052] The hardness (puncture strength) of the Nata de Coco sheet obtained by this production method is not limited to, but is preferably 100 to 1,800 kgf, more preferably 300 to 1,500 kgf, and even more preferably 600 to 1,200 kgf. The puncture strength can be measured using a creep meter (for example, Yamaden RE2-33005C).

[0053] The Nata de Coco sheet obtained by this production method has suppressed formation of unevenness on the surface, and the milk film can be easily peeled off and removed. The evaluation of the unevenness on the surface of the Nata de Coco sheet and the peeling and removal of the milk film can be evaluated by the method described in the examples below.

[0054] After step (B), the Nata de Coco sheet can be cut into a desired shape to obtain a final product such as a food product.

[0055] According to this manufacturing method, the degree of unevenness on the surface of the Nata de Coco sheet can be reduced, for example, the filtration process and slicing process can be eliminated. In addition, the labor required to peel off the milk film can be reduced, for example, the process of peeling off the milk film can be almost eliminated. Therefore, according to this manufacturing method, compared to conventional manufacturing methods, it is possible to reduce the number of steps, improve the yield, and reduce the amount of waste. It is extremely useful.

[0056] In addition, if coconut milk, fruit puree, vegetable puree, etc. are not used as raw materials for Nata de Coco, for example, if a synthetic medium or coconut water is used as the sole raw material, a milk film is not formed. However, according to this manufacturing method, the formation of unevenness in the Nata de Coco sheet can be suppressed, which is still useful. In other words, according to this manufacturing method, the formation of unevenness in the Nata de Coco sheet can be suppressed, and the filtration process and slicing process can be eliminated, which reduces the number of steps and improves the yield. It is still useful.

[0057] In this production method, when coconut milk is used as a raw material for Nata de Coco, for example, the amount added to the culture medium can be reduced, and it is easy to obtain and inexpensive, so it has high cost benefits. From this viewpoint, there is an advantage that Nata de Coco sheets can be produced at lower cost.

[0058] <Application> The Nata de Coco sheet obtained by this production method can be used for food applications, cosmetics, quasi-drug applications, pharmaceutical applications, etc. [Example]

[0059] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples as long as it does not depart from the gist of the invention. In the examples, "%" means by mass.

[0060] Example 1: Stirred culture First, acetic acid bacteria (Gluconacetobacter xylinus) were pre-cultured, and the bacteria were grown in an acetic acid culture medium (10 5 The CFU / g was adjusted. Specifically, 1 g of the inoculum was dissolved and suspended in 9 mL of 0.9% sterilized saline, and the suspension was serially diluted and then cultured in HS (Hestrin-Schram) liquid medium (0.5% polypeptone, 0.5% yeast extract, 2.0% D-glucose, 0.115% citric acid, 0.3% disodium hydrogen phosphate) at 30°C for 48 hours to prepare an acetic acid culture medium.

[0061] (A) Seed culture process 20 mL of the acetic acid culture solution was inoculated into 180 mL of the medium shown in Table 1 below, and agitation culture was carried out using the following culture apparatus. The agitation culture conditions were a culture temperature of 30°C, a culture time of 48 hours, and agitation power requirement per unit volume (P V ) 9.9 W, and the rotation speed of the stirring blade was 150 rpm.

[0062] [Table 1]

[0063] Stirring culture equipment Culture tank: 300 mL cylindrical beaker [tank diameter (D): 7.6 cm] Agitator blade: propeller blade [blade diameter (d): 5.0 cm, blade width (b): 1.0 cm, blade width (b) / blade diameter (d) = 0.2] Blade diameter (d) / tank diameter (D)=0.66

[0064] In agitation culture, the liquid density [kg / m 3 ] is 1,015 kg / m 3 The liquid level (H) was 4.9 cm, and the ratio (H / D) of the liquid level (H) to the tank diameter (D) was 0.65.

[0065] (B) Main culture process 30 mL of the seed medium obtained in step (A) was inoculated into a tray filled with 270 mL of the medium shown in Table 1, and static culture was performed to obtain a nata de coco sheet. The culture temperature was 30 ° C. and the culture time was 10 days. The tray used for static culture had inner dimensions of 131 mm length x 93 mm width x 53 mm depth.

[0066] [Evaluation test of the surface irregularities of Nata de Coco sheets] The surface of the obtained Nata de Coco sheet was rinsed with running water (or gently stroked), and then visually observed, and the degree of surface unevenness was evaluated according to the following criteria. The results are shown in Table 2. (Evaluation criteria) ◎(excellent)...The surface is very smooth and looks great. ◯ (very good): The surface is smooth or has minimal irregularities and looks good. × (poor): The surface is not smooth or has large irregularities, making it look unattractive.

[0067] [Evaluation test for peeling and removal of milk film] The surface of the obtained Nata de Coco sheet was rinsed with running water (or gently stroked), and the state of the milk film afterwards was visually observed and evaluated according to the following criteria. The results are shown in Table 2. (Evaluation criteria) ◎ (Excellent)...The milk film peels off easily and does not remain on the surface at all. 〇 (very good)...The milk film peels off easily, but a small amount remains on the surface. × (poor) ...The milk film does not peel off and remains on the entire surface.

[0068] [(A) Measurement test of the average particle size of cellulose aggregates after the seed culture process] Using a laser diffraction / scattering particle size distribution analyzer (HORIBA, model LA-960V2), the particle size distribution of the major axis diameter of the cellulose aggregates contained in the seed medium after the seed culture step (A) was determined, and the particle size at 50% cumulative frequency (median diameter) was measured as the average particle size. The results are shown in Table 2.

[0069] [(A) Measurement test of viable cell count after seed culture process] After step (A), 1 g of the seed medium was dissolved and suspended in 9 mL of 0.9% sterilized saline, and the suspension was serially diluted and then cultured at 30°C for 48 hours on HS (Hestrin-Schram) agar medium (0.5% polypeptone, 0.5% yeast extract, 2.0% D-glucose, 0.115% citric acid, 0.3% disodium hydrogen phosphate, 1.5% agar), and the number of colonies was counted. The results are shown in Table 2.

[0070] <Examples 2 to 7: Stirred Culture> (A) Agitation power required in the seed culture process (P V ) and the rotation speed of the stirring blade were changed as shown in Table 2. A Nata de Coco sheet was obtained in the same manner as in Example 1. Various tests were performed on the obtained Nata de Coco sheet in the same manner as in Example 1. The results are shown in Table 2.

[0071] <Reference example 1: Stationary culture> 20 mL of the acetic acid culture solution was inoculated into a culture vessel containing 180 mL of the medium shown in Table 1, and static culture was carried out (seed culture step) at a culture temperature of 30°C for 48 hours. The culture tank used in the seed culture step was a 300 mL cylindrical beaker [tank diameter (D): 7.6 cm]. 30 mL of the seed medium obtained in the seed culture step was inoculated into a tray filled with 270 mL of the medium shown in Table 1, and static culture was performed to obtain Nata de Coco sheets (main culture step). The culture temperature was 30 ° C. and the culture time was 10 days. The tray used in the main culture step had inner dimensions of 131 mm long x 93 mm wide x 53 mm deep. Various tests were performed on the obtained Nata de Coco sheet in the same manner as in Example 1. The results are shown in Table 2.

[0072] Comparative Example 1: Shaking Culture 20 mL of the acetic acid culture solution was inoculated into 180 mL of the medium shown in Table 1, and shake culture was carried out using a shaker (Bw-201, manufactured by Yamato Co., Ltd.) (seed culture step). The culture conditions were a shaking speed of 125 rpm, a culture temperature of 30°C, and a culture time of 48 hours. The culture vessel used in the seed culture step was a 300 mL Erlenmeyer flask [vessel diameter (D): 9.0 cm]. 30 mL of the seed medium obtained in the seed culture step was inoculated into a tray filled with 270 mL of the medium shown in Table 1, and static culture was performed to obtain Nata de Coco sheets (main culture step). The culture temperature was 30 ° C. and the culture time was 10 days. The tray used for static culture had inner dimensions of 131 mm long x 93 mm wide x 53 mm deep. Various tests were performed on the obtained Nata de Coco sheet in the same manner as in Example 1. The results are shown in Table 2.

[0073] [Table 2]

[0074] (Static culture evaluation) It was confirmed that the milk film was difficult to peel off and remove from the Nata de Coco sheet obtained by static culture alone, as in Reference Example 1. Specifically, Figure 1 is a photograph showing the appearance of the Nata de Coco sheet of Reference Example 1, which was taken by placing the Nata de Coco sheet on the floor and placing a camera above it. As shown in Figure 1, the milk film on the surface of the Nata de Coco sheet did not peel off easily and remained throughout.

[0075] (Evaluation of shaking culture) As in Comparative Example 1, the Nata de Coco sheet obtained through the seed culture process by shaking culture and the main culture process by static culture was confirmed to have significant surface irregularities. Specifically, Figure 2 is a photograph showing the appearance of the Nata de Coco sheet of Comparative Example 1, which was taken by placing the Nata de Coco sheet on the floor and installing a camera above it. As shown in Figure 2, the surface of the Nata de Coco sheet was significantly uneven, not smooth, and looked unattractive.

[0076] (Evaluation of agitation culture: Agitation power requirement (P V ) is 8.0W or more) As in Examples 1 to 7, the stirring power required (P V The nata de coco sheets obtained through a seed culture process in which stirring culture is performed to a predetermined value or more and a main culture process by static culture have suppressed the formation of surface irregularities and the milk film is easily peeled off and removed. Specifically, FIG. 3 is a photograph showing the appearance of the Nata de Coco sheet of Example 2, which was taken by placing the Nata de Coco sheet on a floor surface and placing a camera above it. FIG. 4 is a photograph showing the appearance of the Nata de Coco sheet of Example 3, which was taken by placing the Nata de Coco sheet on a floor surface and placing a camera above it. FIG. 5 is a photograph showing the appearance of the Nata de Coco sheet of Example 7, which was taken by placing the Nata de Coco sheet on a floor surface and placing a camera above it. As shown in FIGS. 3 to 5, according to Examples 2, 3, and 7, it was confirmed that there was almost no unevenness on the surface and the milk film was easily peeled off and removed. In other words, the surface of the Nata de Coco sheet was smooth and had a good appearance. In addition, the milk film on the surface of the Nata de Coco sheet was easily peeled off.

[0077] Furthermore, photographs were similarly taken of Examples 1 and 4 to 6 to confirm that there were almost no irregularities on the surface and that the milk film was easily peeled off and removed.

[0078] <Example 8: Scale-up test> (A) Seed culture process 30 L of the acetic acid culture solution was inoculated into 270 L of the medium shown in Table 1, and agitation culture was carried out using the following culture apparatus. The agitation culture conditions were a culture temperature of 30°C, a culture time of 48 hours, and agitation power requirement (P V ) 14.1 W, and the rotation speed of the stirring blade was 50 rpm.

[0079] Stirring culture equipment Fermentation tank: 500L tank [tank diameter (D): 95cm] Mixing blades: Pitch paddle blades, 2 blades, 2 stages [blade diameter (d): 50 cm, blade width (b): 15 cm, blade width (b) / blade diameter (d) = 0.3] Blade diameter (d) / tank diameter (D)=0.53

[0080] In agitation culture, the liquid density [kg / m 3 ] is 1,015 kg / m 3 The liquid level (H) was 42.3 cm, and the ratio (H / D) of the liquid level (H) to the tank diameter (D) was 0.45.

[0081] (B) Main culture process 500 mL of the seed medium obtained in step (A) was inoculated into a tray filled with 4,500 mL of the medium shown in Table 1, and static culture was performed to obtain Nata de Coco sheets. The culture temperature was 30 ° C. and the culture time was 10 days. The tray used for static culture had inner dimensions of 599 mm length x 373 mm width x 63 mm depth.

[0082] Various tests were performed on the obtained Nata de Coco sheet in the same manner as in Example 1. As a result, as in Examples 1 to 7, the formation of surface irregularities was suppressed and the milk film was easily peeled off and removed. It was confirmed that.

[0083] From the above, (A) a seed culture step (A) in which a seed culture medium containing acetic acid bacteria having cellulose-producing ability is used and a stirring culture is performed with a stirring power requirement of 8.0 W or more per unit volume, and a main culture step (B) in which a portion of the seed culture medium obtained by the step (A) is inoculated into the main culture medium and static culture is performed. It was confirmed that the formation of surface irregularities can be suppressed and the milk film can be easily peeled off and removed.

[0084] <Example 9: When coconut water is used as an ingredient> Nata de Coco sheets were obtained in the same manner as in Example 1, except that the medium used in (A) the seed culture step and (B) the main culture step was changed to replace coconut milk with an equal amount of coconut water. 6 is a photograph showing the appearance of the Nata de Coco sheet of Example 9. The Nata de Coco sheet was placed on the floor and photographed with a camera placed above it. The surface of the obtained Nata de Coco sheet was smooth and had a good appearance. In addition, no milk film was formed on the surface of the Nata de Coco sheet.

[0085] <Example 10: Preparation of face mask-shaped nata de coco sheet> (A) Agitation power required in the seed culture process (P V ), the rotation speed of the stirring blade was the same as in Example 1, (B) the shape of the tray used for static culture in the main culture step was changed to the shape of a face mask (an oval with internal dimensions of 200 mm length x 250 mm width x 63 mm depth), and the culture time was changed to 5 days. Except for this, a face mask-shaped Nata de Coco sheet was obtained in the same manner as in Example 1. The obtained Nata de Coco sheet was washed with water to deacidify it, then lightly dehydrated and immersed in a cosmetic liquid to create a cosmetic face mask.

[0086] Although the above examples show specific embodiments of the present invention, the examples are merely illustrative and should not be construed as limiting. Various modifications that are obvious to those skilled in the art are intended to fall within the scope of the present invention. [Industrial Applicability]

[0087] The Nata de Coco sheet obtained by the production method of the present invention can be used for foods, cosmetics, quasi-drugs, pharmaceuticals, etc.

Claims

1. A method for producing a nata de coco sheet comprising the following steps (A) and (B). (A) A seed culture step in which a seed medium containing acetic acid bacteria having cellulose producing ability is used to perform agitation culture with an agitation power requirement of 8.0 W or more per unit volume. (B) A main culture step in which a portion of the seed medium obtained in the step (A) is inoculated into a main culture medium and static culture is performed.

2. The method for producing a nata de coco sheet according to claim 1, wherein the stirring power required in the step (A) is 9.0 W or more and 3,000 W or less.

3. The method for producing a nata de coco sheet according to claim 1 or 2, wherein the average particle diameter of the cellulose lumps contained in the seed medium obtained in the step (A) is 50 μm or less.

4. The method for producing a nata de coco sheet according to claim 1 or 2, wherein the average particle diameter of the cellulose lumps contained in the seed medium obtained in the step (A) is less than 30 μm.

5. The method for producing a nata de coco sheet according to claim 1 or 2, wherein the medium in the step (B) is a medium containing coconut milk.

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