JP3962585B2 - Stevia extract manufacturing method - Google Patents

Description

[0001]
[Technical field to which the invention belongs]
The present invention relates to a method for producing stevia extract.
[0002]
[Prior art]
Stevia extract is widely used as a growth material for growth of useful microorganisms in soil in the agricultural field, as a growth-promoting activator, as a nutritional supplement feed additive in the livestock field, and as an active ingredient in health foods and various cosmetics. Has been done. As a method for producing this stevia extract, a method proposed in Japanese Patent No. 2577105 is known. In this method, the dried stevia leaves and stems are pulverized and powdered, put into water and boiled to obtain a stevia extract, and the extract is concentrated, fermented and matured.
[0003]
[Problems to be solved by the invention]
However, the above method requires a lot of labor for the boiling and concentration steps, and has a high production cost such as low energy efficiency when concentrating. In addition, many boilings occur in the boiling and concentrating steps, which have problems such as inhibiting fermentation and remaining as impurities to lower the quality.
The present invention has been conceived from such a fact, and an object of the present invention is to provide a method for producing a stevia extract with improved quality, simple production, and reduced production costs.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the method for producing a stevia extract according to the present invention comprises boiling stevia stem powder under a pressure higher than atmospheric pressure, and then removing solids to obtain an extract; The extract is heated while being decompressed to a pressure lower than atmospheric pressure, and concentrated while scooping or scooping out impurities, and the concentrated extract is applied to a pressure of 0.2 ± 0.02 MPa by a fermenter. It is characterized by having a step of primary fermentation in a pressed state and a step of fermenting and aging the concentrated solution subjected to primary fermentation at a temperature of 25 ° C to 40 ° C.
[0006]
Moreover, the process which dries the liquid stevia extract in any one of the above to a powder form can also be added.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be specifically described based on examples. Stevia used as a raw material is grown by pesticide-free organic cultivation in any of plant seedlings, cutting seedlings, or seeded seedlings, and a matured one is harvested once a year (early October). The mowing is performed by removing the stevia leaf by hand picking and then cutting the stevia stem at a location about 10 cm from the root. Since stevia leaves generate a lot of boiling when boiled, and this drilling has been found to cause fermentation inhibition and purity reduction, stevia leaves are not used in the present invention.
[0008]
The stevia stalks after cutting in this way are naturally dried or dried with a drier to bring the moisture content to 5% to 10%. Stevia stems dried in this way are pulverized to about 20 mesh to obtain Stevia stem powder.
[0009]
This stevia stem powder is boiled with water and extracted. Conventionally, this extraction process has been carried out at atmospheric pressure using an atmospheric kettle. However, hot water extraction and heat concentration with an atmospheric pressure kettle took time and effort for the amount of heat. Therefore, in the present invention, the extraction process is performed as follows.
[0010]
First, 100 liters of water is added to 20 kg of the above stevia stem powder, and the mixture is left to stand for about 30 minutes at room temperature. As a result, the dried stevia stem powder absorbs moisture and becomes soft, and the active ingredients can be easily taken out.
[0011]
Then, it is boiled by heating at a temperature of 125 ± 10 ° C. under a pressure of about 0.15 ± 0.02 MPa, which is higher than atmospheric pressure, in a pressure cooker. Since it is pressurized to atmospheric pressure or higher with a pressure cooker, the boiling point rises to 125 ± 10 ° C., which promotes the elution of active ingredients contained in stevia stem and can be efficiently extracted into hot water. The extraction time varies depending on the state of stevia stem powder, but is about 30 minutes to 1 hour.
[0012]
The extract thus obtained is dehydrated to obtain an extract containing no solids. The dehydration method is not particularly limited, but in this embodiment, it is put in a cotton bag and dehydrated by a rotary dehydrator or a screw dehydrator to obtain about 80 liters of a complete extract containing no solids.
[0013]
Conventionally, the step of obtaining this extract was performed under atmospheric pressure. For this reason, it has been very troublesome to extract active ingredients. Briefly, stevia leaves and stem powder are boiled for about 1 hour in a boiled state, squeezed with a squeezing machine to obtain the first extract, and the squeezed residue is again simmered for about 1 hour and The extract was obtained twice, and the first and second extracts were mixed to obtain an extract. On the other hand, in the method of the present invention, the pressure is increased to the atmospheric pressure or higher by the pressure cooker, so that the active ingredient can be extracted in a short time due to high temperature.
[0014]
Next, about 80 liters of the extract from which the solid content has been removed is put into a vacuum concentrator, and the pressure is reduced to less than atmospheric pressure at a temperature of 80 ± 5 ° C. and a pressure of 0.06 ± 0.01 MPa. Concentrate for a time to obtain about 60 liters of concentrated liquid having a concentrated specific gravity of 1.3.
[0015]
Conventionally, this step has been performed by a method in which the mixed extract is boiled and concentrated under atmospheric pressure. Therefore, the concentration did not proceed unless the temperature was raised to 100 ° C., which is the normal boiling point of water.
[0016]
However, in the present invention, the heat concentration is performed under a reduced pressure lower than the atmospheric pressure, so that the boiling point of the extract is lowered and the latent heat of vaporization is reduced, so that both the time required for concentration and the amount of heat can be saved.
[0017]
During the concentration process, a crack occurs on the surface of the extract. It has been found that this crack is a cause of inhibiting fermentation and inhibiting active ingredients. Therefore, in the present invention, the net is scooped by rotating a net of about 50 mesh. When the concentration has progressed, the sugar content of the concentrate is measured, and when it reaches 8 to 25 degrees, the concentration is stopped.
[0018]
The concentrated solution thus obtained is put into a fermenter and subjected to primary fermentation over 24 hours in a state of being pressurized to about twice the atmospheric pressure at a temperature of 30 ° C. and a pressure of 0.2 ± 0.02 MPa. Stevia fermentation is basically natural fermentation in which stevia is fermented in a natural state without adding yeast from outside. Conventionally, the above concentrated liquid is directly fermented in an aging tank. However, in this method, the amount of yeast contained in stevia is small and easily contaminated with bacteria. Therefore, only the contaminated bacteria grow and the concentrated solution may rot, and the stability of fermentation is lacking. On the other hand, in this invention, since a concentrate is put into a fermenter and it ferments under predetermined temperature and predetermined pressure, it can prevent rot and can ferment stably. That is, many of the miscellaneous bacteria do not have pressure resistance, and thus are easy to kill or suppress proliferation. On the other hand, yeast required for fermentation has pressure resistance, and can be preferentially grown. As a result, it has become possible to suppress the propagation of various bacteria and allow stable fermentation.
[0019]
When a fermenter is used, the fermentation period can be shortened from about 1/2 to about 1/3 of the normal time, but a large number of fermenters are required. Therefore, only the primary fermentation, that is, the stage in which the yeast is proliferated preferentially is performed in the fermenter, and the subsequent fermentation and aging are performed in the aging tank.
[0020]
After the completion of primary fermentation, the concentrate is transferred to an aging tank and aged at 25 to 40 ° C. for 30 to 360 days. The reason for the aging period is that the longer the aging time, the higher the sugar content. In the above-mentioned Patent No. 2577105, the ripening temperature was 20 ° C. to 25 ° C., but in the present invention, there are few varieties, there is no miscellaneous bacteria after primary ripening, and the yeast is increasing. For this reason, ripening can be performed at a temperature of 25 ° C. or higher, and the ripening period shown in the above-mentioned Japanese Patent No. 2577105 can be shortened to about half of the ripening period. Impurities such as dead bodies and crystals of yeast are generated during the fermentation and ripening, so a net of about 70 mesh was rotated into the liquid so that these could be removed.
[0021]
As described above, the fermentation of stevia is natural fermentation without adding yeast, but when promoting the fermentation, the yeast previously cultured is added to the concentrate, and then the primary fermentation process or the fermentation / ripening process is performed. It may be done.
[0022]
The fermented ripening liquid thus obtained is stevia extract. This stevia extract is used as it is or diluted with water or the like. Since the stevia extract manufactured by the method of the present invention has high purity, the dilution ratio can be made larger than the conventional one. For example, foliar spraying is carried out on various fruit trees for agricultural use or soil irrigation is used, but conventional stevia extract has been diluted about 700 to 1000 times. On the other hand, the stevia extract by the manufacturing method of this invention was diluted 1500 to 2000 times, and the equivalent effect has been confirmed.
[0023]
The above stevia extract is a liquid, but this liquid may be dried to form a powder. By making the extract into a dry powder form, it is possible to simplify storage and use. The powdered stevia extract may be used as it is, or may be used by dissolving in water or the like. As a drying method, hot air drying may be used, but freeze drying is preferable because it hardly causes a change in quality.
[0024]
【The invention's effect】
As described above, according to the present invention, the stevia stem powder is boiled in a state of being pressurized to a pressure higher than atmospheric pressure, and then the solid is removed to obtain an extract, and the extract is subjected to atmospheric pressure. Heating at a lower pressure and concentrating while scooping or scooping out impurities with a net, and primary fermentation in a state where the concentrated extract is pressurized to about twice the atmospheric pressure by a fermenter And the step of fermenting and aging the concentrated fermented liquid at a temperature of 25 ° C. to 40 ° C. By scooping out impurities and impurities, the number of miscellaneous bacteria is reduced, which is higher than conventional 25 ° C. Aging at ~ 40 ° C is possible. Furthermore, by performing primary fermentation in a state where the pressure is higher than atmospheric pressure, it becomes easy to kill germs and suppress growth, and a high quality stevia extract can be obtained at low cost.

Claims (2)

After boiling Stevia stalk powder under a pressure higher than atmospheric pressure, the solid is removed to obtain an extract, and the extract is heated to a pressure lower than atmospheric pressure and heated to a net. The step of concentrating while scooping out impurities or impurities, the step of primary fermentation of the concentrated extract under a pressure of 0.2 ± 0.02 MPa by a fermenter, and the concentration subjected to primary fermentation And a step of fermenting and aging the liquid at a temperature of 25 ° C to 40 ° C.   A method for producing a stevia extract, comprising a step of drying the stevia extract according to claim 1 into a powder form.