JPS6366190B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a technology for continuous fermentation of alcoholic beverages using immobilized yeast, which is provided with a pre-tank, and is capable of producing alcoholic beverages of excellent quality stably for a long period of time while preventing bacterial contamination of the raw sugar solution. Concerning the manufacturing method for producing. [Prior Art] Continuous production of alcohol using immobilized yeast is already at the stage of practical application. Regarding the continuous production of alcoholic beverages, attempts have been made to continuously brew wine and beer. In the continuous brewing of these alcoholic beverages, countermeasures against bacterial contamination and quality of the final product are particularly problematic. As a countermeasure against contamination by various bacteria (especially bacteria) during conventional continuous fermentation, boiling sterilization of the raw sugar solution (beer, etc.)
Alternatively, a method is used in which acid is added to the raw sugar solution to lower the pH to below 4.0 (alcohol, wine). However, in the field, it is difficult to continuously pass boiling-sterilized raw sugar solution aseptically for a long period of time.
This is quite difficult and costly. Furthermore, when the pH of the raw sugar solution is lowered, the acidity of the alcoholic beverage that is not distilled increases, resulting in a product with a strong sour taste. Furthermore, in either method, storage of the sugar solution before sending it to the continuous fermentation column poses a problem. Especially in the case of alcoholic beverages that use solid starchy raw materials,
Since saccharification is performed in batches and the saccharified solution is continuously passed through the column, storage of the saccharide solution is a major problem. [Problems to be Solved by the Invention] The problems to be solved by the present invention are to solve the problems of the above-mentioned conventional techniques and to provide a continuous fermentation production method that can be applied to all alcoholic beverages. That is,
To provide a method in which sugar solution can be stored without boiling sterilization or pH adjustment of the raw material sugar solution, and continuous brewing can be carried out for a long period of time without bacterial contamination. [Means for solving the problem] The above problem can be solved by installing a pre-tank containing free yeast in front of the immobilized yeast column used for continuous fermentation, and collecting a large number of necessary yeast in the presence of the generated alcohol. This is achieved by keeping it in a maintained state and adding sugar solution to the pre-tank. Furthermore, in the immobilized yeast column following this pre-tank, the alcohol concentration and number of yeast can be kept higher than in the conventional system without a pre-tank, so there is no bacterial contamination and the final alcoholic beverage is Alcohol concentration also increases. The present invention is basically a manufacturing method in which a pre-tank containing free yeast is provided in front of an immobilized yeast column, and continuous fermentation of alcoholic beverages is carried out. , contains a method of keeping it in a suspended state by stirring. In the present invention, the free yeast contained in the pre-tank may be cultured separately and added, but the immobilized yeast may be immobilized by circulating the immobilized yeast column and the pre-tank before starting continuous fermentation. More effective is a method in which free yeast eluted from propagating yeast is grown in a pre-tank. When yeast grows in the front tank, alcohol is produced, but by keeping the alcohol concentration at 4% or more, it is possible to prevent bacterial contamination in the front tank and, by extension, in the immobilized yeast column. The yeast used in the present invention may be any yeast commonly used in alcohol fermentation or brewing, but it also includes a method using killer yeast that has killer activity against wild yeast. [Effect of the invention] According to the continuous fermentation method of the present invention, solid raw materials can be
The saccharified liquid that has been saccharified in batches is sterilized by boiling and the pH is
Since continuous production without bacterial contamination is possible for a long period of time without adjusting the temperature below 4.0, stable alcoholic beverages can be produced at low cost even on an on-site scale. Furthermore, even in the case of alcoholic beverages with low acidity, such as sake, it is possible to continuously brew products with low acidity. Further, according to the present invention, there is no discernible difference in the components of the continuously brewed alcoholic beverages compared to products produced by the conventional batch method, and the alcoholic beverages are rather superior in terms of sensory experience. [Example] Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited thereto. Example 1 According to a conventional method, rice flour was liquefied and saccharified using an enzyme agent, and then carbon-filtered, and a koji saccharification liquid obtained by saccharifying rice malt and carbon-filtering was mixed. The pH of approximately 5.5 was adjusted to 4.0 using lactic acid, and a saccharification solution for continuous fermentation was prepared. See Figure 1. Killer Association No. 10 yeast, bred according to conventional methods,
100ml of Killer No. 10 immobilized yeast gel obtained by immobilization with sodium alginate by a known method
was packed into a 300ml column. 600ml of saccharification liquid in the front tank
was connected to the immobilized yeast column and the saccharification solution was circulated. The temperature of the pre-tank was 15°C, and the temperature of the immobilized yeast column was 20°C. After 4 days of circulation, the fermentation solution eluted from the immobilized yeast column was collected into another vessel when the alcohol concentration exceeded 4%, and continuous fermentation was started. The flow rate was kept constant at 10 ml/hr (SV0.1). The amount of saccharification solution (240 ml) that decreased each day from the next day was added to the front tank. When the alcohol concentration in the front tank was maintained at 1 to 5% (average 3%), there was bacterial contamination and the acidity increased; When maintained at 4 to 8% (average 6%), there was no bacterial contamination and the acidity remained constant even after long operating days. Furthermore, no contamination with wild yeast was observed. Under these conditions, the alcohol concentration of the continuous fermentation solution eluted from the immobilized yeast column was 12-13% (v/
v), which was a high value and remained stable for more than a month.
See Figures 2a to 2d. Example 2 The pH of the rice flour saccharification solution adjusted in the same manner as in Example 1 was
Three types of saccharification solutions were prepared: 4.0, 4.5, and 5.5 (unadjusted). Three reactors were prepared in which an immobilized yeast column prepared in the same manner as in Example 1 was connected to a front tank equipped with a stirring device, and 400 ml of three types of saccharification solutions with different pHs were added to each front tank. In the same manner as in Example 1,
The alcohol concentration in the front tank is all 4-8% (average 6%).
%). Under the conditions of pre-tank temperature 15℃, immobilized yeast column 20℃, flow rate 10ml/hr (SV0.1),
12% alcohol was produced stably over 1.5 months. The production of acidity was constant in all cases and no increase was observed. See Figures 3a to 3d. When the eluate during continuous fermentation was examined, no bactea or wild yeast was detected when the pre-tank was stirred, regardless of whether the saccharification solution at pH 4.0, 4.5, or 5.5 was used. See Table 1. After storing the continuous fermentation eluate at 5° C. for one week, yeast was removed by centrifugation and analysis and alcohol consumption were performed.
No difference was observed in terms of composition compared to the batch-produced control. In the sensory test, PH
The classification using a saccharification solution of 5.5 (PH not adjusted) and stirring in the front tank was also excellent in terms of durability. See Table 2.

【table】

【table】 [Brief explanation of drawings]

Figure 1 is a flowchart showing the method for preparing the saccharified rice flour solution in Example 1, and Figure 2a is a flowchart showing the method for preparing the saccharified rice flour solution in Example 1.
Figures 2b to 2d are graphs showing the properties of the continuous fermentation liquid, Figure 3a is a diagram of the continuous fermentation apparatus in Example 2, and Figures 3b to 3.
Figure d is a graph showing the properties of the continuous fermentation solution.

Claims (1)

[Scope of Claims] 1. Alcoholic beverages produced by immobilized yeast, characterized in that when producing alcoholic beverages by a continuous fermentation method using immobilized yeast, a front tank containing free yeast is provided in front of the immobilized yeast column. continuous fermentation method. 2. By stirring the pretank containing free yeast,
The method according to claim 1, wherein the yeast in the front tank is kept in a suspended state. 3. The yeast contained in the front tank is used by refluxing free yeast eluted from the immobilized yeast column.
A method according to claim 1. 4 Alcohol concentration in the front tank containing free yeast is 4%
The method according to claim 1, which is the above. 5. The method according to claim 1, wherein the sugar solution used is unsterilized. 6. The method according to claim 1, wherein the yeast used for immobilization is killer yeast.