JPH0251587B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing yeast extract. Yeast extracts have long had problems such as yeast odor, strong coloring, and bacterial contamination during the manufacturing process. Although many methods to solve this problem have been proposed and implemented, and some results have been achieved, the above problem still hinders the expansion of the use of yeast extract. I can say that. Furthermore, when producing yeast extract by the autolysis method, solvents such as ethyl acetate and toluene are added, but the use of such solvents is not preferable from the viewpoint of the purpose and quality of the yeast extract, and from the viewpoint of flame resistance. Undesirable. moreover,
When brewer's yeast is used as a raw material for producing yeast extract, a step is required to remove hop bitter substances. In view of the above circumstances, the present inventors conducted repeated studies to improve the method for producing yeast extract. As a result, they discovered that the above-mentioned problems could be solved at once by pre-treating the raw material yeast with an aqueous ethyl alcohol solution, and based on this knowledge, they completed the present invention. The present invention is a method for producing a yeast extract, which is characterized in that, in producing the yeast extract, raw yeast is pretreated with an aqueous ethyl alcohol solution having a concentration of 10 to 40%. There are various methods for producing yeast extract, such as acid hydrolysis, enzymatic methods, and autolysis, and the present invention can be applied to any known production method. Similarly, the raw material yeast to be used is not limited, and any yeast can be used. The method for producing yeast extract by autolysis is widely practiced, and because it relies on the action of intracellular enzymes, it is a method that is limited in the processing of raw yeast. Therefore, the present invention will be explained below by taking as an example a method for producing yeast extract using an autolysis method. In the present invention, raw material yeast is pretreated using an aqueous ethyl alcohol solution with a concentration of 10 to 40%. In addition to adding ethyl alcohol from the outside, ethyl alcohol produced by fermentation of raw material yeast can be used as part or all of the ethyl alcohol. As mentioned above, when the alcohol aqueous solution is mixed with the raw material yeast, it is brought into contact with the pressed yeast (moisture 75%) at a concentration of 10 to 40% to act on it.
This refers to the overall concentration after addition of ethyl alcohol, since yeast is often handled in slurry form. In addition, the economically effective concentration of ethyl alcohol for each purpose is 20% or more for removing yeast odor, about 40% for lightening coloring, 10% or more for controlling germs, and 10% or more for solvent replacement. 10% for
The amount above is about 40% for removing bitter substances. There are no particular restrictions on the temperature of pretreatment, but
In general, the temperature should not be above 40℃, where autolysis occurs, but should be at the temperature of the normal manufacturing environment, that is, below 40℃.
Usually, a sufficient effect can be obtained at a temperature of about 0 to 30°C. The treatment time ranges from a short period of time, such as mixing and stirring the alcoholic aqueous solution with yeast and immediately separating it, to 8 hours, usually within 1 hour, preferably 5 hours.
The duration ranges from a minute to an hour. After pre-treating the raw material yeast by contacting it with ethyl alcohol in this way, the ethyl alcohol aqueous solution and the yeast are separated,
Yeast is used for producing yeast extract. Note that harmful components such as odorous components and coloring components in the yeast are transferred to the ethyl alcohol side by this treatment. According to the present invention, the yeast odor is removed from the raw material yeast and the coloring is also lightened, so the obtained yeast extract does not have the unpleasant odor or coloration that is conventional. Moreover, contaminating bacteria from raw yeast are removed, and there is no need to use solvents such as ethyl acetate or toluene.
Hop bitterness is also reduced or eliminated.
By applying the method of the present invention, the number of dead yeast cells may increase, the yeast may become bacteriostatic, or dehydration may occur, but these may affect the progress of yeast autolysis and the yield of yeast extract. has no effect. Further, the used ethyl alcohol aqueous solution can be recovered and reused. Next, the present invention will be explained with reference to examples. Example 1 A predetermined amount of 99.5% ethyl alcohol was added to muddy yeast produced as a by-product from a beer factory (containing 40% pressed yeast) to adjust the ethyl alcohol concentration as shown in the table below, and the mixture was heated for 5 minutes. After stirring, yeast was collected by centrifugation. This yeast was weighed, and a portion was used for water content measurement and measurement of the number of contaminant bacteria, and the remaining yeast was suspended in 10 times the amount of water, and a yeast extract was produced by a conventional autolysis method. However, 0.5% ethyl acetate (to liquid) was added to untreated yeast, and no ethyl acetate was added to yeast treated with ethyl alcohol aqueous solution. In addition, the ethyl alcohol concentration is determined by the specific gravity method.
The extract content was determined using a refractometer method, the number of bacteria was determined using standard agar medium supplemented with actidione, and the degree of coloration of the extract was determined using autolysis liquid.
The absorbance at 420 mm was measured after filtration with a 0.45μ membrane. To determine the extent of enzyme action, total nitrogen and amino nitrogen were measured using the Kjeldahl method and the formol method, respectively. Furthermore, the yeast odor and bitterness evaluations of the yeast extract were based on the consensus opinion of five yeast extract manufacturing engineers. For comparison, a yeast extract was produced using untreated yeast that was not pretreated with an aqueous ethyl alcohol solution. The results are shown in Table 1.

【table】

[Table] Yeast odor present weak
None None None
Bitterness present little
Weak Almost none None
*1 Weight ratio before and after pretreatment

Claims (1)

[Claims] 1. In producing yeast extract, yeast is
A method for producing yeast extract, characterized by pretreatment with a 10-40% ethyl alcohol aqueous solution. 2. The method according to claim 1, wherein the pretreatment is to separate the ethyl alcohol aqueous solution and the yeast after contacting them at a temperature of 40° C. or less for a period of up to 1 hour.