JP7426651B2 - Method for producing sweet potato juice and sweet potato juice - Google Patents

Description

The present invention relates to a method for producing sweet potato juice and sweet potato juice using sweet potato as a raw material.

BACKGROUND ART Juice obtained by squeezing sweet potato and sweet potato juice using the same have been known. The natural oligosaccharides contained in sweet potatoes, and some colored sweet potatoes contain a high content of anthocyanidins, a purple pigment, and β-carotene, a yellow/orange pigment, making it easy to ingest these nutrients. It is attracting attention as a food material.

Generally, pressing methods and centrifugation methods are used to separate the juice from vegetables and fruits, but sweet potatoes are rich in fiber and starch, and in order to maintain a suitable viscosity, It was necessary to remove these effectively and separate the juice. However, simply removing the fibers and starch by centrifugation or filtration does not bring out the sweetness and flavor from the sweet potato, and there is a problem in that the yield rate further deteriorates.

In relation to such problems, for example, Patent Document 1 discloses a sweet potato beverage characterized by containing an enzymatic decomposition product of sweet potato degraded using a combination of a fiber-degrading enzyme and a starch-degrading enzyme. . Furthermore, for example, Patent Document 2 discloses that under conditions that substantially inactivate the polyphenol oxidase contained in sweet potato but activate amylase, the maltose content of sweet potato becomes 1.0 to 10% by weight. A first step of heat-treating the sweet potato, a second step of squeezing the heat-treated sweet potato, and treating the squeezed juice to reduce the viscosity caused by starch granules in the squeezed juice. A method for producing sweet potato juice is disclosed, which is characterized by passing through a third step of:

Japanese Patent Application Publication No. 9-107934 Japanese Patent Application Publication No. 10-215835

According to the above-mentioned Patent Documents 1 and 2, sweet potato juice and sweet potato juice of good quality can be obtained by a method using enzymes for fibrous and starch substances.

However, according to the research conducted by the present inventors, it is difficult to adjust the sweetness due to sugars produced by enzymatic decomposition, and there is a problem in that it affects the flavor when sweet potato juice is prepared.

Therefore, the object of the present invention is to provide a method for producing sweet potato juice, which uses the squeezed juice obtained by squeezing sweet potato, and which has a moderate sweetness. The purpose is to provide a manufacturing method.

The present inventors have conducted extensive research to achieve the above object and have completed the present invention.

That is, in its first aspect, the present invention is a method of producing sweet potato juice by subjecting sweet potato to blanching, hydration, and crushing processes, and then squeezing the obtained processed product after enzyme treatment to obtain a squeezed liquid. The present invention provides a method for producing sweet potato juice, characterized in that the enzyme treatment is performed using maltotriose-producing amylase.

In the method for producing sweet potato juice, the enzyme treatment is preferably performed using a fiber-degrading enzyme in addition to the maltotriose-producing amylase.

In the method for producing sweet potato juice, the juice contains carbohydrates in an amount of 70% by mass or more and 98% by mass or less based on the total solid content, and the starch content is 10% by mass or less based on the total solid content. It is preferable to obtain a juice having a glucose content of 10% by mass or less based on the total solid content.

In the method for producing sweet potato juice, it is preferable to obtain a juice containing 0.75% by mass or more of anthocyanin compounds based on the total solid content in terms of aglycone.

In the method for producing sweet potato juice, it is preferable to concentrate the juice after the juice is squeezed to obtain a juice having a Brix value of 45 or more and 55 or less.

In a second aspect, the present invention provides a method for producing sweet potato juice, which includes a step of mixing the sweet potato juice obtained by the above-described production method with other raw materials. .

In the method for producing sweet potato juice, the other raw material is preferably one or more selected from the group consisting of water, lemon juice, acidulant, and flavor.

According to the present invention, since maltotriose-generating amylase is used to prepare sweet potato juice, the content of glucose, which is a sweet component among sugars produced by starch decomposition, can be reduced without causing a decrease in flavor or nutritional components. It is possible to provide sweet potato juice with suppressed Therefore, it is possible to provide sweet potato juice that exhibits moderate sweetness.

There is no particular restriction on the variety of sweet potato used as a raw material in the present invention. For example, commonly available products such as Beniasuma and Benisatsuma may be used, or Ayamurasaki, Murasakimasari, Yamakawa Murasaki, Tanegashima Murasaki, Chiran Murasaki, Kyushu 109, J-Red, Benihayato, Sunny Red, and Akemurasaki, which are rich in anthocyanin compounds. The so-called colored sweet potatoes may be used, such as purple sweet potatoes such as , and orange sweet potatoes such as Benihayato, Healthy Red, Kyushu No. 120, and Higashiyama, which are rich in carotene compounds. Among these, Ayamurasaki, which is rich in anthocyanin compounds known to have various physiological effects, is preferably exemplified.

In the method for producing sweet potato juice according to the present invention, sweet potato is first subjected to blanching, hydration, and crushing treatments.

By subjecting the sweet potato to blanching, enzymes inherent in the sweet potato can be deactivated and starch contained in the sweet potato can be gelatinized. Thereby, it is possible to suppress the disordered decomposition of sweet potato components and obtain a squeezed liquid with stable quality. In addition, by gelatinizing starch, it becomes easier to react with enzymes, promoting efficient decomposition. The conditions for blanching are not particularly limited, and typically, for example, the center of the raw sweet potato is steamed or soaked in steam or water heated to 90 to 100°C. This can be carried out by treating for 5 to 30 minutes at a temperature of preferably 70°C or higher, more preferably 75°C or higher.

Furthermore, by adding water to the sweet potato, the enzyme treatment can be carried out efficiently. The amount of water added is not particularly limited, and typically, for example, it is preferably 0.5 to 20 times the amount of sweet potato raw material, more preferably 1 to 10 times, and 3 to 10 times the amount of sweet potato raw material. Even more preferred is 6 times the amount.

Furthermore, by subjecting the sweet potato to crushing treatment, the treatment with enzymes can be carried out efficiently. The means of crushing is not particularly limited, and typically, for example, a hammer crusher, mixer, chopper, stone mill type crusher, cutter such as a disk cutter, fruit cutter, ultra-precision high-speed crusher, etc. are used. Bye. Although the degree of crushing may be carried out as appropriate, it is preferable to crush the treated product that has been subjected to the above-mentioned water addition treatment until it has fluidity to the extent that the contents can be well mixed and dispersed. is preferred. Furthermore, in order to allow the enzyme to act uniformly, it is desirable to select a method that can be ground more finely. In addition, "crushing" in such a crushing process includes cases generally referred to as "pulverization", "grinding", "shredding", etc.

There is no particular restriction on the order of processing the raw materials, but from the viewpoint of work efficiency, it is preferable to perform blanching first, and more preferably blanching, hydration, and crushing in this order. These processes may be performed at timings that overlap with each other.

The raw sweet potato may be cut into a suitable shape. For example, it may be cut into strips with a thickness of 20 to 40 mm using a device such as a slicer, or it may be cut into pieces of a predetermined size. Furthermore, as a treatment for the raw sweet potato, it may be peeled using a device such as a steam peeler. By subjecting the raw sweet potato to such a processing treatment, it is possible to increase the efficiency of preparing the processed product obtained through at least the above-described blanching, hydration, and crushing treatments. The timing of processing the raw sweet potato to give it this shape is not particularly limited, and typically, for example, it may be before the above-mentioned blanching process, or before the above-mentioned hydration process. The process may be performed before the above-mentioned crushing process. However, if it is desired to recover components contained in or near the skin of sweet potato, it is preferable not to perform peeling treatment.

Note that the raw sweet potato after the above-mentioned blanching treatment can be temporarily frozen or stored for use in producing sweet potato juice at any other time.

In the method for producing sweet potato juice according to the present invention, the treated product obtained through the above-described blanching, hydration, and crushing treatments is subjected to enzyme treatment with maltotriose-generating amylase.

The maltotriose-producing amylase used in the enzyme treatment may be any enzyme that has the activity of acting on starch to mainly produce maltotriose. Specifically, any enzyme that has the activity of producing maltotriose using a polysaccharide having an α(1→4)-glucan structure such as amylose, amylopectin, or glycogen as a substrate may be used. is glucan
It may be an enzyme belonging to 1,4-α-maltotriohydrolase (EC 3.2.1.116, also known as maltotriose-forming enzyme). For example, Japanese Patent Publication No. 57-6915 describes a maltotriose-producing amylase derived from a microorganism belonging to Streptomyces griseus. Furthermore, Japanese Patent Publication No. 15315/1983 describes a maltotriose-producing amylase derived from a microorganism belonging to the genus Bacillus. Further, JP-A-3-251173 describes a maltotriose-producing amylase derived from a microorganism belonging to the genus Microbacterium. Furthermore, JP-A-2012-016309 describes a maltotriose-producing amylase derived from a microorganism belonging to Streptomyces sinnamonensis. Furthermore, as a commercially available enzyme preparation, for example, the product name "AMT1.
2L" (manufactured by Amano Enzyme Co., Ltd.) are on the market.

Enzymatic treatment with maltotriose-producing amylase breaks down the starch contained in sweet potatoes and produces low-molecular sugars, but maltotriose-producing amylase has a low production efficiency, at least for glucose, and this results in Sweetness can be suppressed.

One type of maltotriose-producing amylase may be used singly, or two or more types may be used in combination.

The conditions for enzyme treatment are not particularly limited, and may be carried out under conditions suitable for the enzyme used. Typically, for example, the processed raw material sweet potato is placed in a suitable container such as a tank together with the enzyme used, and heated to 35 to 65° C., more typically, by a heating means while being stirred by a stirring means. This can be carried out by reacting for 15 to 120 minutes at a temperature in the range of 50 to 60°C. After the enzyme treatment, a treatment may be performed to inactivate the used enzyme, such as raising the temperature to 70°C or higher, more preferably 90°C or higher. As another example, the enzyme may be added first, the liquid may be gradually accumulated over 15 to 60 minutes, and the juice may be started when the entire amount has accumulated. In addition, when using two or more types of enzymes in combination, treatment with different types of enzymes may be performed in stages, or enzyme treatment may be performed by adding different types of enzymes together to the processed raw material sweet potato. can.

In the method for producing sweet potato juice according to the present invention, in a preferred embodiment, enzyme treatment is performed with maltotriose-generating amylase and an enzyme that decomposes fibers and proteins (hereinafter sometimes simply referred to as "fiber-degrading enzyme"). ) may also be used. According to this, the fibers of sweet potato are efficiently decomposed, and the amount of juice obtained from the raw material, that is, the juice extraction rate (yield in terms of solid content) is improved, and the yield is improved. Examples of fiber-degrading enzymes include cellulases, hemicellulases, pectinases, proteases, and the like. One type of fiber-degrading enzyme may be used alone, or two or more types may be used in combination.

The conditions for the enzyme treatment when using the above-mentioned fiber-degrading enzyme are not particularly limited, similar to the conditions for the enzyme treatment with the maltotriose-generating amylase described above, and are suitable for the enzyme used. Just go. Typically, for example, the processed raw material sweet potato is placed in a suitable container such as a tank together with the enzyme used, and heated to 35 to 65° C., more typically, by a heating means while being stirred by a stirring means. This can be carried out by reacting for 15 to 120 minutes at a temperature in the range of 50 to 60°C. After the enzyme treatment, a treatment may be performed to inactivate the used enzyme, such as raising the temperature to 70°C or higher, more preferably 90°C or higher. As another example, the enzyme may be added first, the liquid may be gradually accumulated over 15 to 60 minutes, and the juice may be started when the entire amount has accumulated. In addition, when using two or more types of enzymes in combination, treatment with different types of enzymes may be performed in stages, or enzyme treatment may be performed by adding different types of enzymes together to the processed raw material sweet potato. can. When maltotriose-producing amylase and fibrous degrading enzyme are treated separately, the order of these treatments is arbitrary, and the treatment with maltotriose-producing amylase and fibrous degrading enzyme may be repeated.

Note that the use of enzymes other than the above-mentioned maltotriose-producing amylase or the above-mentioned enzyme treatment with degrading enzymes for fibers or proteins is not excluded, and it is also possible to use other enzymes as desired.

In the method for producing a sweet potato juice according to the present invention, the processed sweet potato obtained through the processes of blanching, hydration, and crushing is subjected to the enzyme treatment as described above, and then the juice is squeezed. The juice processing yields a juice from which juice residues such as pulp are removed.

The means for squeezing the juice is not particularly limited, and examples include centrifugal juice extractors such as decanters and separators, and squeeze-type juice extractors such as filter presses, belt presses, and screw presses. Therefore, you can select one from among them according to your purpose.

After the juice processing, various treatments such as sterilization, concentration, filtration, and homogenization may be performed to obtain the juice according to the present invention.

In a preferred embodiment of the method for producing sweet potato juice according to the present invention, the juice is concentrated after squeezing and the Brix value is 45 or more and 55 or less, more preferably the Brix value is 47.5 or more and 52.5 or less, and even more. Preferably, a squeezed liquid having a Brix value of 49 or more and 51 or less may be obtained. According to this, it is convenient for use, for example, as a concentrated squeezed liquid for sweet potato juice, which is temporarily stored by freezing or the like and used for producing sweet potato juice at any time. In this case, the quality of each lot of squeezed juice is inspected to control the quality of the sweet potato juice product, or in some cases, different lots are mixed to adjust the quality of the sweet potato juice product. It is also possible.

The means of concentration is not particularly limited, and for example, concentrators such as single-effect cans and multi-effect cans are known, and any one of them may be selected depending on the purpose.

The sweet potato juice obtained as described above typically contains carbohydrates from 70% by mass to 98% by mass, and preferably from 80% by mass to 97% by mass, based on the total solid content. is more typical, and it is even more typical that the content is 90% by mass or more and 96% by mass or less. In addition, maltotriose is typically contained as a product resulting from the action of maltotriose-generating amylase, and typically contains 1% by mass or more and 20% by mass or less based on the total solid content, and 1% by mass or more. It is more typical to contain 15% by mass or less, it is even more typical to contain 2% by mass or more and 7.5% by mass or less, and it is especially typical to contain 3% by mass or more and 5% by mass or less. It is. The starch content in such sweet potato juice is preferably 10% by mass or less based on the total solid content, and the glucose content is preferably 10% by mass or less based on the total solid content. It is more preferable that the content is 7.5% by mass or less based on the total solid content, and the content of glucose is 7.5% by mass or less based on the total solid content. Further, it is preferable that the anthocyanin compound is contained in an amount of 0.75% by mass or more, and more preferably 1% by mass or more, based on the total solid content in terms of its aglycone. There is no particular restriction on the lower limit of the content of starch or glucose, but normally, if it is starch, it is at least 1% by mass or more, more typically at least 3% by mass or more, based on the total solid content of sweet potato juice. Some degrees may be included. Alternatively, in the case of glucose, it may be contained in an amount of about 0.5% by mass or more, more typically at least 1% by mass or more, based on the total solid content of the sweet potato juice. Furthermore, there is no particular restriction on the upper limit of the content of anthocyanin compounds, but based on the content naturally contained in sweet potatoes, the amount of anthocyanin compounds in terms of their aglycones is at most the total solid content of sweet potato juice. An upper limit of about 5% by weight, more typically about 3% by weight at most, is considered.

The sweet potato juice obtained as described above has the flavor and nutritional components derived from sweet potato, and since the starch content is within the above range, the juice does not have a powdery taste when prepared. Moreover, since the content of glucose is within the above range, sweet potato juice having a moderate sweetness without being too sweet can be obtained. In addition, if the carbohydrate content per solid content of the sweet potato juice is less than the above range, it will tend to be difficult to retain the sweet potato flavor generally exhibited by the sweet potato-derived components.

On the other hand, in the method for producing sweet potato juice according to the present invention, sweet potato juice is produced using the sweet potato juice obtained as described above. The raw materials used for producing the sweet potato juice are not particularly limited as long as they are the raw materials generally used for producing juice products. Typically, examples include water, lemon juice, flavor, plant-derived extract, acidulant, thickener, sweetener, citrus juice, and the like. Among these, from the viewpoint of compatibility with the flavor of sweet potato, it is preferable to use lemon juice, an acidulant, and a flavoring agent. In addition, from the viewpoint of improving storage stability, it is preferable to add a pH adjuster such as an organic acid as necessary to adjust the pH to 3.60 to 4.00. In addition, in order to obtain a straight sweet potato flavor, the sweet potato juice obtained as described above should be at least 30% by mass and less than 100% by mass (as a Brix value of 50) in the total mass of the raw materials for sweet potato juice. It is preferably 40% by mass or more and 80% by mass or less, and even more preferably 40% by mass or more and 70% by mass or less.

The sweet potato juice obtained as described above may be provided in a container for one serving, for example, in a container having a capacity of 65 mL or more and 300 mL or less. In this case, it is preferably provided in the form of a packaged beverage containing 200 mg or more and 550 mg or less of anthocyanin compounds in terms of aglycone, and preferably provided in the form of a packaged beverage containing 230 mg or more and 450 mg or less of the anthocyanin compound in one container. It is more preferable that

Note that the contents of various components in this specification can be analyzed, for example, as follows.

・Moisture: 105℃ constant weight drying method ・Carbohydrates: Other than the total amount of quantitative values for moisture, protein (by Kjeldahl method), lipids (by acid decomposition method), and ash (by ashing method) out of the total mass , treated with carbohydrate content.
・Starch: Modified Somogyi method ・Glucose: HPLC method ・Anthocyanin compounds: Bilberry extract According to the food standards, the amount of anthocyanidins after desugarizing glycosides by heating under reflux in hydrochloric acid, based on the amount of delphinidin. It is calculated from the specific absorbance using the absorbance method.
・Maltotriose: HPLC method

Further, the Brix value can be measured using a commercially available saccharimeter or the like.

The present invention will be specifically described below with reference to Examples, but these Examples do not limit the scope of the present invention.

(enzyme)
Table 1 summarizes the contents of the enzyme preparations used in the test.

(Brix value)
The Brix of the sample at 20° C. was measured using a sugar meter (Atago RX-5000α, manufactured by Atago).

(Preparation example 1-1)
A concentrated juice for sweet potato juice (set Brix value: Bx50) was produced using Ayamurasaki, a colored sweet potato, as a raw material. Specifically, the raw sweet potato was washed with a drum type washing machine, peeled using a steam peeler, and further cut into 20 mm thick pieces using a slicer. This was put into a blanching tank and blanched by heating at 93° C. for 15 minutes. After adding water to the same amount as the raw material, it was crushed with a hammer crusher. After crushing, the solution was sent to a tank and subjected to enzyme treatment. Among the enzyme preparations shown in Table 1, (1) the product name "Glukuzyme AF6" (manufactured by Amano Enzyme Co., Ltd.), (2) the product name "Gluku SBG" (manufactured by Amano Enzyme Co., Ltd.), and (3) the enzyme products. Using Hemicellulase M (manufactured by HBI Co., Ltd.), 0.125 parts by mass of enzyme preparation (1) was added to 100 parts by mass of raw sweet potato, and enzyme preparation (2) was added to 100 parts by mass of raw sweet potato. 0.125 parts by mass of the enzyme preparation (3) was added to 100 parts by mass of raw sweet potato. After reacting for 15 minutes at 50 to 55°C while stirring with a stirring device provided in the tank, the juice is squeezed using a decanter-type juicer, and the obtained primary juice is sterilized with UHT and then sterilized using a triple-effect can. It was concentrated to a value of Bx50 (final Brix value approximately Bx50.10-50.30).

(Preparation example 1-2)
A concentrated juice for sweet potato juice (set Brix value: Bx50) was produced using Ayamurasaki, a colored sweet potato, as a raw material. Specifically, the raw sweet potato was washed with a drum type washing machine, peeled using a steam peeler, and further cut into 20 mm thick pieces using a slicer. This was put into a blanching tank, heated at 93° C. for 15 minutes to perform blanching treatment, water was added so that the amount was three times that of the raw material, and then crushed with a hammer crusher. After crushing, the solution was sent to a tank and subjected to enzyme treatment. Among the enzyme preparations shown in Table 1, (4) brand name "AMT1.2L" (manufactured by Amano Enzyme Co., Ltd.) and (5) brand name "Cellulase TP-5" (manufactured by Kyowa Kasei Co., Ltd.) were used as enzymes. Then, 0.125 parts by mass of enzyme preparation (4) was added to 100 parts by mass of raw sweet potato, and 0.125 parts by mass of enzyme preparation (5) was added to 100 parts by mass of raw sweet potato. After reacting at 50 to 55°C for 15 minutes, the juice was squeezed using a decanter-type juicer, and the obtained primary juice was sterilized with UHT and then concentrated in a triple-effect can to a set Brix value of Bx50 ( Final Brix value is approximately Bx50.10-50.30).

(Preparation example 1-3)
Concentrated juice for sweet potato juice (set Brix value: Bx50) was produced in the same manner as in Preparation Example 1-2, except that raw materials harvested at different times were used as Ayamurasaki raw materials (final Brix value was approximately Bx50.10). ~50.30).

(Preparation example 1-4)
A concentrated juice for sweet potato juice (set Brix value: Bx50) was produced using Ayamurasaki, a colored sweet potato, as a raw material. Specifically, the raw sweet potato was washed with a drum washer, peeled using a steam peeler, and further cut into 40 mm thick pieces using a slicer. This was put into a blanching tank and blanched by heating at 93° C. for 15 minutes, and after adding water to an amount six times the amount of the raw material, it was crushed with a hammer crusher. After crushing, the solution was sent to a tank and subjected to enzyme treatment. Among the enzyme preparations shown in Table 1, (4) brand name "AMT1.2L" (manufactured by Amano Enzyme Co., Ltd.) and (5) brand name "Cellulase TP-5" (manufactured by Kyowa Kasei Co., Ltd.) were used as enzymes. Then, 0.125 parts by mass of enzyme preparation (4) was added to 100 parts by mass of raw sweet potato, and 0.03 part by mass of enzyme preparation (5) was added to 100 parts by mass of raw sweet potato. After reacting at 50 to 55°C for 15 minutes, the juice was squeezed using a decanter-type juicer, and the obtained primary juice was sterilized with UHT and then concentrated in a triple-effect can to a set Brix value of Bx50 ( Final Brix value is approximately Bx50.10-50.30).

(Preparation example 1-5)
Concentrated juice for sweet potato juice (set Brix value: Bx50) was produced in the same manner as in Preparation Example 1-4, except that raw materials harvested at different times were used as Ayamurasaki raw materials (final Brix value was approximately Bx50.10). ~50.30).

(Preparation example 1-6)
Concentrated juice for sweet potato juice (set Brix value: Bx50) was produced in the same manner as Preparation Example 1-5, using raw materials harvested at the same time as in Preparation Example 1-5, and without peeling. (Final Brix value approximately Bx50.10-50.30).

Table 2 shows the combinations and amounts of enzyme preparations used in the preparation of the concentrated juices obtained in Preparation Examples 1-1 to 1-6.

<Test Example 1>
The concentrated juice obtained in Preparation Examples 1-1 to 1-6 was analyzed for sugar composition and anthocyanin content. As for the analysis method, the starch content was determined by the modified Somogyi method, and the content of various sugars such as glucose, fructose, galactose, sucrose, lactose, and maltose was determined by the HPLC method. Further, the total solid content was determined by determining the moisture content by a constant weight drying method at 105° C., and determining the total solid content as the difference from the total amount. Furthermore, for carbohydrates, the sum of quantitative values for moisture (by constant weight drying method at 105°C), protein (by Kjeldahl method), lipid (by acid decomposition method), and ash (by ashing method) out of the total mass. Anything other than quantity was treated as carbohydrate content. On the other hand, regarding the anthocyanin content, in accordance with the Bilberry Extract Food Standards, the amount of anthocyanidins after desugarizing the glycosides by heating under reflux under acidic hydrochloric acid is determined from the specific absorbance using the absorbance method based on the amount of delphinidin. Calculated. The results are shown in Table 3.

As a result, in Preparation Example 1-1 in which glucoamylase and α-amylase were used for enzyme treatment, the glucose content was 29.0g/100g (60.3% by mass based on the total solid content), whereas In Preparation Examples 1-2 to 1-6 in which maltotriose-generating amylase and cellulase were used for enzyme treatment, the glucose content was 1.0 g/100 g to 2.9 g/100 g (relative to the total solid content). 2.1% by mass to 6.03% by mass). When the obtained concentrated squeezed juice was diluted with water to the concentration of sweet potato juice and the taste was separately evaluated, it was found that Preparation Example 1-1 had a strong sweetness, whereas Preparation Examples 1-2 to 1 -6 had a moderate sweetness. On the other hand, the anthocyanidin content was 345 mg/100g (0.7% by mass based on the total solid content) in Preparation Example 1-1, while in Preparation Examples 1-2 to 1-6. was 505 mg/100g to 669 mg/100g (1.0% by mass to 1.4% by mass based on the total solid content).

<Test Example 2>
From the results of Test Example 1, it was considered that the taste and anthocyanin content of sweet potato juice may be affected by the type of enzyme used when producing sweet potato juice. Therefore, we investigated the influence of the type of enzyme by adjusting various conditions such as the amount of water added to the raw material and the amount of enzyme preparation added during enzyme treatment. Therefore, in this test example, we investigated the sugar composition and anthocyanin content of sweet potato juice prepared on a laboratory scale, rather than using equipment for producing concentrated juice for sweet potato juice, when the type of enzyme was changed.

Specifically, 1 to 2 kg of the raw material Ayamurasaki (without peeling) is washed by hand, sliced with a knife into approximately 40 mm thick slices, soaked in boiling water and heated at 98°C for 15 minutes for blanching treatment. After adding water to double the amount, the mixture was crushed using a twin-screw crusher and then a mixer. After crushing, they were transferred to a container and subjected to enzyme treatment using the combinations and amounts of enzymes shown in Table 4.

Among the enzyme preparations shown in Table 1, the enzymes include (2) brand name "Gluk SBG" (manufactured by Amano Enzyme Co., Ltd.), (4) brand name "AMT1.2L" (manufactured by Amano Enzyme Co., Ltd.), and (5) ) The product name "Cellulase TP-5" (manufactured by Kyowa Kasei Co., Ltd.) was used in the combinations and amounts shown in Table 4. After reacting at 55°C for 1 hour while stirring with a tabletop stirrer, the supernatant was recovered by centrifugation (3,000 rpm, 10 minutes), passed through a 60 mesh sieve to obtain a crude filtrate, and then incubated at 95°C. The enzymes were inactivated by heat treatment to obtain a sweet potato juice.

The obtained juice was evaluated for the following properties: Brix value (Bx sugar content), pH, and juice extraction rate (according to formula (1) below). In addition, in order to simply examine the presence or absence of starch decomposition, the degree of color change was sensory evaluated using a titrant solution for iodine starch reaction. Furthermore, regarding the taste, the level of off-taste and sweetness was sensory evaluated.

(juice extraction rate)
Squeezing rate (%) = (mass of obtained juice/total mass after adding water when water is added to raw materials) x 100...(1)

(starch decomposition)
A color change due to the addition of a titrant solution for iodine starch reaction (a 95% aqueous ethanol solution containing 10 w/v % iodine) was observed.

○ No change △ Slight change × Change

(taste)
○ Good △ Slightly poor × Poor

The results are shown in Table 5.

As a result, in Preparation Example 2-1 in which maltotriose-producing amylase, cellulase, esterase, and tannase were used in combination as enzymes used in the enzyme treatment, and in Preparation Example 2-2 in which only maltotriose-producing amylase was used, the obtained There was no difference in the properties of the sweet potato juice, with good starch decomposition and taste.

On the other hand, in Preparation Example 2-3, in which only cellulase, esterase, and tannase were used together as the enzymes used in the enzyme treatment, and maltotriose-generating amylase was not used, starch decomposition was poor and the viscosity was too high for use in juice. It was considered too much. In addition, regarding the taste, it was felt that it had a slightly different taste compared to Preparation Example 2-1 and Preparation Example 2-2.

On the other hand, in Preparation Example 2-4 in which glucoamylase and α-amylase were used as the enzymes used in the enzyme treatment, the obtained sweet potato juice had a strong sweet taste, and it was considered that the sweet potato juice was too sweet to be used for juice ( The proportion of glucose is 16.2% by mass in solid content).

The juice of Preparation Example 2-1 and the juice of Preparation Example 2-4 were examined for their sugar composition and anthocyanidin content in the same manner as in Test Example 1. In addition, the content in terms of Bx50 was calculated by multiplying the Brix value of the prepared juice by a factor such that it becomes Bx50. The results are shown in Table 6.

As a result, in Preparation Example 2-1 in which maltotriose-producing amylase was used as the enzyme used in the enzyme treatment, the content in the prepared juice was the same as in Preparation Example 2-4 in which glucoamylase was used. Despite the extent, when converted to Bx50, the anthocyanidin content was about 1.6 times higher. This was thought to be because the enzyme had a high Brix value, and when converted to Bx50, the concentration was low.

<Test Example 3>
Sweet potato juice was prepared on a laboratory scale in the same manner as in Test Example 2, except that the combinations and amounts of enzymes shown in Table 7 were used.

The obtained juice was evaluated for the following properties: Brix value (Bx sugar content), pH, and juice extraction rate (according to formula (1) above). The results are shown in Table 8.

As a result, in Preparation Example 3-1 in which maltotriose-producing amylase and cellulase were used in combination as enzymes used in the enzyme treatment, the obtained sweet potato yield was lower than in Preparation Example 3-2 in which only maltotriose-producing amylase was used. Although there were no major differences in the Brix value or pH properties of the juice, the juice extraction rate was 89.9% in Preparation Example 3-2, whereas the juice extraction rate was 89.9% in Preparation Example 3-1. It was 97.5%, which was significantly high.

From the above, it has become clear that by increasing the amount of cellulase added, it is possible to improve the juice extraction rate and, by extension, the yield.

Claims (7)

In a method for producing sweet potato juice, in which sweet potato is subjected to blanching, hydration, and crushing treatments, and the obtained processed product is squeezed after enzyme treatment to obtain a squeezed juice, the enzyme treatment is performed using maltotriose-generating amylase. A method for producing a sweet potato juice , characterized in that the sweet potato juice contains maltotriose, which is a product of the action of the maltotriose-producing amylase, in a ratio of 1% to the total solid content. A method for producing a sweet potato juice containing % by mass or more and 20% by mass or less . 2. The method for producing sweet potato juice according to claim 1, wherein the enzyme treatment is performed using a fiber-degrading enzyme in addition to the maltotriose-producing amylase. Squeezed juice containing 70% by mass or more and 98% by mass or less of carbohydrates based on the total solid content, the starch content is 10% by mass or less based on the total solid content, and the glucose content is less than the total solid content. The method for producing a sweet potato juice according to claim 1 or 2, wherein the juice has a content of 10% by mass or less. The method for producing a sweet potato juice according to any one of claims 1 to 3, wherein a juice containing anthocyanin compounds in an amount of 0.75% by mass or more based on the total solid content in terms of aglycone thereof is obtained. The method for producing a sweet potato juice according to any one of claims 1 to 4, wherein the juice is concentrated after the juice is squeezed to obtain a juice having a Brix value of 45 or more and 55 or less. A method for producing sweet potato juice, comprising a step of mixing the sweet potato juice obtained by the production method according to any one of claims 1 to 5 with other raw materials. 7. The method for producing sweet potato juice according to claim 6, wherein the other raw material is one or more selected from the group consisting of water, lemon juice, acidulant, and flavoring agent.