How to prepare plums

Abstract

The goal is to artificially ripen unripe green plums in a short period of time, enabling the production of plums equivalent to naturally ripened, fully matured plums. [Solution] In the decomposition step S4, the decomposition of cyanogenic glycosides such as amygdalin contained in the pulp of raw plums promotes the production of hydrogen cyanide and benzaldehyde. In the detoxification step S5, the produced hydrogen cyanide and benzaldehyde are detoxified. In the high-temperature sterilization step S7, the detoxified plums are sterilized at high temperature. In the ultraviolet irradiation step S8, the plums are further ripened by ultraviolet irradiation. As a result, unripe green plums can be artificially ripened in a short period of time, such as a few days, and plums equivalent to naturally ripened yellow plums that mature over about a month can be obtained.

Description

Technical Field

[0005]

[0001] This invention relates to a method for processing plums that artificially ripen harvested unripe plums.

Background Art

[0002] Plums reach the harvest season from June to July. The flesh and seeds of freshly harvested green plums contain amygdalin, which is a cyanogenic glycoside. When amygdalin is hydrolyzed, hydrocyanic acid and benzaldehyde are produced. Hydrocyanic acid is highly toxic and eating it may cause hydrocyanic acid poisoning, and benzaldehyde is a pungent and unpleasant component with high antibacterial properties. Therefore, raw green plums are not suitable for direct consumption.

[0003] On the other hand, it is known that amygdalin is decomposed by salt or alcohol and becomes non-toxic, and that heating causes emulsin to be deactivated and amygdalin is no longer produced. Therefore, conventionally, pickling in salt to make dried plums, pickling in alcohol to make plum wine, or heating to deactivate emulsin to produce plum extract has been carried out.

[0004] By the way, the harvest time of plums is limited, and it is difficult to store green plums as they are. Therefore, previously, as described in Patent Document 1, the inventor of the present application froze the plum fruits, thawed the frozen plum fruits under predetermined conditions, then immersed them in plum vinegar solution with a predetermined salt concentration, and then dried them to make dried plums, and proposed an invention. According to the invention described in Patent Document 1, by using storable frozen plums as raw materials, it is possible to produce plums on an annual planned basis, and excellent effects such as stable quality, stable supply, and cost reduction can be obtained.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] In the case of pickled plums (umeboshi), recent consumer health consciousness has led to a demand for low-salt or salt-free umeboshi. To meet these consumer demands, methods such as washing the umeboshi with water to reduce salt content are currently employed. However, this requires adding a water-washing step to the normal umeboshi manufacturing process, which increases the number of manufacturing steps. In the case of umeboshi manufactured according to the invention described in Patent Document 1, which contains high levels of salt, a water-washing step is also required to reduce the salt content, inevitably increasing the number of steps.

[0007] Furthermore, plums are a highly nutritious fruit, containing relatively high amounts of potassium, iron, and vitamin E. For example, they contain twice, six times, and 33 times more of these nutrients than apples. Potassium, along with sodium, is a mineral that maintains and regulates the osmotic pressure of cells. Because potassium helps excrete excess salt (sodium), it is known to be a representative nutrient that lowers blood pressure. Much of the iron is used in hemoglobin in red blood cells and is known to play a role in oxygen transport. Therefore, since iron deficiency can easily lead to anemia, plums, which are rich in iron, are said to be effective. Vitamin E is one of the fat-soluble vitamins and is known to have high antioxidant power.

[0008] Thus, in order to make the most of the potassium, iron, and vitamin E contained in plums, it is desirable to develop a method for removing cyanogenic glycosides, cyanide, and benzaldehyde from raw plums, just as with mature plums. This would allow the plums to be eaten as is, or frozen for long-term storage, and would also enable the production of various processed products using salt-free plums.

[0009] Regarding the kernel of the plum seed, a method for removing cyanogenic glycosides such as amygdalin has been proposed, as described in, for example, Japanese Patent Publication No. 3605548. The specific details of this method are as follows: The seed coat is peeled off from the plum kernel with the seed coat still attached, the mixture of the peeled seed coat and plum kernel is immersed in an aqueous solution of an appropriate salt concentration, the plum kernel that floats to the top of the aqueous solution is removed, and the plum kernel from which the seed coat has been peeled is rinsed in water to remove water-soluble amygdalin and other substances. However, this method removes amygdalin and other substances from the plum kernel, and is not a method for removing cyanogenic glycosides such as amygdalin, or hydrogen cyanide and benzaldehyde produced by the decomposition of cyanogenic glycosides, from the plum fruit itself, and therefore cannot be directly applied to unripe green plums.

[0010] This invention was made to solve the above-mentioned problems, and aims to provide plums that are equivalent to naturally ripened, fully mature plums by artificially ripening unripe green plums in a short period of time. [Means for solving the problem]

[0011] To achieve the above-mentioned objectives, the plum processing method is characterized by comprising: a first step of washing harvested unripe plums with water and immersing them in warm water at 50-65°C for 10-30 minutes; a second step of heating the plums that have undergone the first step by maintaining a temperature of 55-65°C for 10-20 minutes; a third step of sterilizing the plums that have undergone the second step by placing them in a sealed container that transmits ultraviolet light and heating them at a high temperature of 85-90°C; and a fourth step of exposing the plums that have undergone the third step, along with the container, to ultraviolet light.

[0012] With this configuration, in the first step, the harvested unripe plums are washed with water and immersed in warm water at 50-65°C for 10-30 minutes, which promotes the decomposition of cyanogenic glycosides such as amygdalin by emulsin, an enzyme contained in the plum pulp. This decomposition of cyanogenic glycosides produces hydrogen cyanide and benzaldehyde.

[0013] In the second step, the plums are kept at a temperature of 55-65°C for 10-20 minutes, accelerating their ripening and detoxifying the hydrogen cyanide and benzaldehyde produced in the first step. In the third step, the plums contained in the container are sterilized at high temperature. In the fourth step, the plums, still in their container, are exposed to ultraviolet light, further accelerating the ripening of the detoxified plums. This allows raw plums to be artificially ripened in a short period of time, just like naturally ripened, fully yellow plums.

[0014] In this case, the fourth step may involve sun-drying the plums in the container for 1 to 3 days, or irradiating the plums in the container with ultraviolet light from an ultraviolet irradiation device for 20 to 40 minutes.

[0015] When drying plums in the sun, the natural flavor of the plums can be brought out more effectively. Alternatively, when using a UV irradiation device, the process can be carried out indoors, allowing the plums to mature continuously 24 hours a day, regardless of weather conditions, thus improving work efficiency.

[0016] Furthermore, the container is preferably a glass jar with a lid that is transparent to ultraviolet light. In this case, since the plums are placed inside the glass jar with a lid, they can be sterilized at high temperatures as is, and after irradiating the glass jar with ultraviolet light, the bottled plums can be stored in an airtight state.

[0017] Furthermore, it is preferable to further include a step of processing the plums that have undergone the first to fourth steps into raw materials for foods such as pickled plums, plum puree, sweet plums, plum jam, and plum wine.

[0018] By doing so, it is possible to eat artificially ripened ume as it is. However, using ume that has been artificially ripened, it is possible to process it into umeboshi with zero salt content without adding salt, or to process it into salty umeboshi by adding an appropriate amount of salt. Also, by adding sugar, etc., it can be processed into ume puree, sweet ume, ume jam, ume liquor, etc. Any of these processed products can utilize the nutrients and umami equivalent to those originally possessed by naturally ripened ume fruits, and can be finished into processed products that are different from existing umeboshi, ume puree, sweet ume, ume jam, and ume liquor.

Effects of the Invention

[0019] According to the present invention, raw ume can be artificially ripened in a short period of time to obtain ume fruits equivalent to naturally ripened yellow ripe ume. Utilizing the nutrients and umami equivalent to those originally possessed by naturally ripe ume fruits, it is possible to provide processed products that are different from existing umeboshi, ume puree, sweet ume, ume jam, and ume liquor.

Brief Description of the Drawings

[0020] [Figure 1] It is a process diagram showing the procedure of the method for processing ume according to the present invention.

Modes for Carrying Out the Invention

[0021] An embodiment of the method for processing ume according to the present invention will be described in detail with reference to FIG. 1.

[0022] As shown in FIG. 1, unripe green ume is harvested in the harvesting step S1. Subsequently, in the washing step S2, the harvested ume is washed with water to wash away soil, dust, etc. adhering to the surface of the ume to clean the ume. Then, in the sorting step S3, the ume is sorted according to grades based on ripeness, color, insect damage, wounds, etc., and each size such as S, M, L to 4L.

[0023] Subsequently, in the decomposition step S4, which is the first step in the present invention, the selected ume plums are immersed in a boiler kettle filled with warm water maintained at 50 to 65°C or a predetermined container for 10 to 30 minutes. At this time, it is desirable to appropriately set the temperature of the warm water and the immersion time according to the temperature of the water used in the washing step S2, the temperature of the air during washing, and the like.

[0024] In the decomposition step S4, the harvested ume plums are washed with water and immersed in warm water at 50 to 65°C for 10 to 30 minutes, whereby the decomposition of cyanogenic glycosides such as amygdalin by emulsin, an enzyme contained in the pulp of the ume plums, is promoted, and hydrocyanic acid and benzaldehyde are generated by the decomposition of the cyanogenic glycosides. In the decomposition step S4, when the temperature of the warm water is less than 50°C or exceeds 65°C, a sufficient effect of promoting the decomposition of amygdalin by emulsin cannot be obtained.

[0025] Thereafter, in the detoxification step S5, which is the second step in the present invention, the ume plums are maintained in a boiler kettle filled with warm water at 55 to 65°C or a predetermined container for 10 to 20 minutes.

[0026] By this detoxification step S5, the ume plums ripen, and the hydrocyanic acid and benzaldehyde generated in the decomposition step S4 disappear and are detoxified. Here, when the temperature of the warm water in the detoxification step S5 is less than 55°C or exceeds 65°C, the disappearance of hydrocyanic acid and benzaldehyde is insufficient, which is not preferable.

[0027] Subsequently, in the bottling step S6, the detoxified ume plums are hermetically stored in a glass bottle with a lid, which is a container capable of transmitting ultraviolet rays.

[0028] Then, in the high-temperature sterilization step S7, which is the third step in the present invention, the bottled ume plums are sterilized at a high temperature of 85 to 90°C together with the glass bottles.

[0029] Thereafter, as the ultraviolet irradiation step S8, which is the fourth step in the present invention, the ume plums sterilized at a high temperature together with the glass bottles are dried in the sun for 1 to 3 days and exposed to the ultraviolet rays of sunlight.

[0030] In this way, by irradiating the plums with ultraviolet light while they are still in the glass jar, the ripening of the detoxified plums can be further accelerated, and in the case of sun-drying, the original deliciousness of the ripe plums can be brought out even more.

[0031] In this way, just like fully ripened plums that naturally mature and turn yellow over about a month, it is possible to artificially ripen unripe green plums in a short period of time of just a few days.

[0032] Subsequently, in processing step S9, the artificially ripened plums are used as raw materials for processed products such as pickled plums, plum puree, sweet plums, plum jam, and plum wine. Each processed product undergoes a different processing step, resulting in the production of various products such as pickled plums, plum puree, sweet plums, plum jam, and plum wine.

[0033] At this time, artificially ripened plums can be eaten as is, but they can also be processed into salt-free pickled plums without adding salt, or into salty pickled plums with an appropriate amount of salt added. Furthermore, artificially ripened plums can be processed into plum puree, sweet plums, or plum jam by adding sugar, and they can be processed into plum wine by soaking them in alcohol and adding sugar.

[0034] All of these processed products utilize the same nutrients and flavor as naturally ripened plums, as described above, to produce products that are distinctly different from existing pickled plums, plum puree, sweet plums, plum jam, and plum wine.

[0035] Therefore, according to the above embodiment, the decomposition step S4 promotes the production of hydrogen cyanide and benzaldehyde by decomposing cyanogenic glycosides such as amygdalin contained in the pulp of raw green plums, the detoxification step S5 detoxifies the produced hydrogen cyanide and benzaldehyde, the detoxified plums are sterilized at high temperature in the high-temperature sterilization step S7, and the plums are further ripened by ultraviolet irradiation in the ultraviolet irradiation step S8. Thus, immature green plums can be artificially ripened in a short period of time, such as a few days, and plums that have ripened to the same level as naturally ripened yellow plums that have matured over about a month can be obtained. Furthermore, the ripened plums can be eaten as is, and processed products that are distinctly different from existing pickled plums, plum puree, sweet plums, plum jam, and plum wine can be provided, utilizing the same nutrients and flavor as naturally ripened plums.

[0036] It should be noted that the present invention is not limited to the embodiments described above, and various modifications other than those described above can be made without departing from the spirit of the invention.

[0037] For example, in the embodiment described above, the fourth step of the present invention, the ultraviolet irradiation step, was described as sun-drying. However, the bottled plums may also be irradiated with ultraviolet light indoors using an ultraviolet irradiation means such as an ultraviolet LED. In this case, the ultraviolet irradiation time using the ultraviolet irradiation means is typically 20 to 40 minutes. Since the ultraviolet irradiation can be done indoors, there is an advantage in that the ripening of the plums can be promoted continuously for 24 hours without being affected by the weather.

[0038] Furthermore, the present invention can be applied to a method for processing plums to artificially ripen harvested, unripe green plums. [Explanation of Symbols]

[0039] S4 ... Disassembly process (first process) S5... Detoxification process (second process) S7… High-temperature sterilization process (third process) S8... Ultraviolet irradiation process (fourth process)

Claims

1. The first step involves washing the harvested unripe plums with water and soaking them in warm water at 50-65°C for 10-30 minutes. The plums that have undergone the first step are heated to a temperature of 55-65°C for 10-20 minutes in a second step, A third step involves placing the plums that have undergone the second step into a sealed container that transmits ultraviolet light and sterilizing them at a high temperature of 85 to 90°C, The fourth step involves exposing the plum fruit, which has undergone the third step, to ultraviolet light while still in the container. A method for processing plums, characterized by including the following:

2. The method for processing plums according to claim 1, characterized in that the fourth step is to sun-dry the plums in the container for 1 to 3 days.

3. The method for processing plums according to claim 1, characterized in that the fourth step involves irradiating the plums, container and all, with ultraviolet light from an ultraviolet irradiation device for 20 to 40 minutes.

4. The method for processing plums according to claim 1, characterized in that the container is a glass bottle with a lid that is transparent to ultraviolet light.

5. The method for processing plums according to claim 1, further comprising the step of processing the plums that have undergone the first to fourth steps into raw materials for food products such as pickled plums, plum puree, sweet plums, plum jam, and plum wine.

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