JP7762403B2 - Fermented fruit juice - Google Patents

Description

The present invention relates to fermented fruit juice products and the like.

Fruit juice from tart sweet oranges such as lemons and limes, and plums, is not often consumed as is because it contains a lot of organic acids such as citric acid and malic acid and has a strong sour taste. It is often used as a secondary ingredient to enhance the palatability of food and drink.

Furthermore, in order to respond to the diversification of preferences, various studies have been conducted regarding the fermentation of fragrant and sour citrus juices. With regard to fermentation by lactic acid bacteria, a method for producing lemon juice fermented liquid (Patent Document 1) has been disclosed, which includes a fermentation step of fermenting lemon juice with lactic acid bacteria, and the lactic acid concentration of the lemon juice fermented liquid is 1000 mass ppm or more based on the total amount. With regard to fermentation by yeast, a method has been disclosed in which invert sugar syrup is added to lime juice, and Saccharomyces cerevisiae is inoculated at a pH of 8.1 to cause fermentation (Patent Document 2).

JP 2015-171341 A Special Publication No. 2015-535425

An object of the present invention is to provide a highly acidic fruit juice fermented product obtained by fermenting fruit juice containing citric acid and/or malic acid using yeast, and a method for producing the same.

The inventors have discovered that a highly acidic fermented fruit juice product can be produced using yeast belonging to the genus Metschnikowia, and have completed the present invention.

That is, the present invention relates to the following aspects [1] to [9].
[1] A fermented fruit juice product having an acidity of 3.0% by weight or more, obtained by fermenting a fruit juice containing citric acid and/or malic acid with a yeast belonging to the genus Metschnikowia that is capable of fermenting the fruit juice.
[2] The fermented fruit juice according to [1], wherein the fruit juice containing citric acid and/or malic acid is a tart sweet orange juice or a fruit juice belonging to the Prunus subgenus.
[3] The fermented fruit juice according to [1] or [2], wherein the ethanol concentration is 1.0% by volume or less.
[4] The fermented fruit juice according to any one of [1] to [3], wherein the content of isoamyl alcohol and/or phenethyl alcohol is increased compared to before fermentation.
[5] A method for producing a fermented fruit juice having an acidity of 3.0% by weight or more, obtained by inoculating a fruit juice containing citric acid and/or malic acid with a yeast belonging to the genus Metschnikowia that can ferment the fruit juice and fermenting the fruit juice.
[6] The method according to [5], wherein the pH at the time of yeast inoculation is 4.0 or less.
[7] The method of manufacturing according to [5] or [6], wherein the fruit juice containing citric acid and/or malic acid is a sour sweet orange juice or a fruit juice belonging to the Prunus subgenus.
[8] The method for producing the lactic acid bacteria according to any one of [5] to [7], characterized in that activated yeast is inoculated.
[9] A food or drink containing the fermented fruit juice according to any one of [1] to [4].

The present invention makes it possible to produce a fermented fruit juice with high acidity by inoculating a yeast belonging to the genus Metschnikowia. It also makes it possible to provide a fermented fruit juice with improved flavor through fermentation. It also provides a production method that allows for the simple production of a fermented fruit juice with high acidity.

The fermented fruit juice of the present invention is a fruit juice fermented product having an acidity of 3.0% by weight or more, obtained by inoculating a fruit juice containing citric acid and/or malic acid with a yeast belonging to the genus Metschnikowia that is capable of fermenting the fruit juice, and fermenting the fruit juice. The yeast to be inoculated is not particularly limited as long as it is a yeast belonging to the genus Metschnikowia that is capable of fermenting a fruit juice containing citric acid and/or malic acid. However, yeast that can grow at an acidity of 3% by weight is preferred, yeast that can grow at an acidity of 4% by weight is more preferred, yeast that can grow at an acidity of 5% by weight is even more preferred, yeast that can grow at an acidity of 6% by weight is even more preferred, and yeast that can grow within a pH range of 2.0 to 3.0 is preferred. Examples of such yeast include Metschnikowia pulcherrima and Metschnikowia agaves, and one or more types may be used.

The yeast belonging to the genus Metschnikowia to be inoculated is not particularly limited as long as it is capable of fermenting fruit juice containing citric acid and/or malic acid, but it is preferable that it has been activated by pre-culture or the like, for example, by shaking a dried, refrigerated, or frozen stock yeast in liquid, preferably at 20 to 40°C, more preferably at 25 to 35°C, for preferably 1 to 72 hours, more preferably 5 to 24 hours, and it is preferable to use a general liquid medium for microorganisms that contains a carbon source, a nitrogen source, inorganic substances, other trace nutrients required by the yeast, etc. Activation means bringing the yeast into a state that facilitates proliferation.

In the present invention, the inoculation of the yeast belonging to the genus Metschnikowia can be carried out by inoculating the yeast into fruit juice containing citric acid and/or malic acid. The amount of inoculation is not particularly limited, but is preferably 0.2 to 10% by volume, more preferably 0.5 to 5% by volume, based on the fruit juice. As fermentation conditions, aerobic fermentation is preferred by aeration, shaking, stirring, etc. The fermentation temperature can be, for example, 10 to 40°C, and preferably 20 to 35°C. The culture time can be, for example, 2 to 72 hours, with 4 to 48 hours being preferred and 6 to 36 hours being more preferred.

The fruit juice to be fermented in the present invention is not particularly limited as long as it contains citric acid and/or malic acid and has a strong sour taste, and preferably has an acidity of 1.0% by weight or more at the start of fermentation, preferably 2.0% by weight or more, more preferably 3.0% by weight or more, more preferably 4.0% by weight or more, even more preferably 5.0% by weight or more, particularly preferably 5.5% by weight or more, and preferably 11% by weight or less. Acidity refers to the content of organic acids in a liquid measured by neutralization titration with sodium hydroxide and converted into citric acid.

The pH at the time of yeast inoculation is not particularly limited, but is preferably 4.0 or less, more preferably 3.5 or less, and even more preferably 3.0 or less. The pH of fruit juice containing citric acid and/or malic acid is usually 4.0 or less, approximately within the range of 2.0 to 3.5. The pH may be adjusted, but since yeast belonging to the genus Metschnikowia can grow even at this pH, there is no particular need to adjust the pH to 5.0 or more. It is preferable not to adjust the pH, since pH adjustment reduces the amount of undissociated citric acid and/or malic acid and lowers the acidity.

The fruit juice containing citric acid and/or malic acid used in the present invention is not particularly limited to any particular raw material as long as it is a fruit juice with a high acidity, and examples thereof include fruit juices with a high content of citric acid and/or malic acid, such as the juice of fragrant citrus fruits such as lemon, lime, tangerine, yuzu, sudachi, kabosu, and bitter orange, and the juice of fruits belonging to the Plum subgenus such as plum, apricot, and plum, and one or more types may be used; for example, concentrated fruit juice may be diluted to the above-mentioned acidity level and used.

Furthermore, fruit juice containing citric acid and/or malic acid preferably has a low sugar content, preferably 8% by weight or less, more preferably 6% by weight or less, even more preferably 5% by weight or less, and particularly preferably 4% by weight or less. It is most preferable that the sugar content is derived from the fruit juice alone, with no added sugars. For example, the sugar content/acidity ratio is preferably 2.0 or less, more preferably 1.5 or less, even more preferably 1.0 or less, and particularly preferably 0.8 or less. Using fruit juice with a low sugar content not only reduces calories but also reduces the concentration of ethanol produced. In the case of high-acidity fruit juice, the sum of acidity and sugar content is measured approximately as Brix sugar content (refractive sugar content), so the sugar content is calculated by subtracting acidity from Brix sugar content to obtain the sugar content/acidity ratio.

In the present invention, nitrogen compounds, minerals, and the like may be used as fermentation aids. Examples of nitrogen compounds that can be used include inorganic nitrogen compounds such as ammonium chloride, ammonium nitrate, ammonium sulfate, and ammonium phosphate; amino acids such as DL-alanine and L-glutamic acid; and organic nitrogen compounds such as peptone, meat extract, yeast extract, malt extract, and corn steep liquor. Examples of minerals that can be used include sodium phosphate, potassium phosphate, manganese sulfate, zinc sulfate, copper sulfate, magnesium sulfate, iron chloride, calcium chloride, ferric chloride, and sodium molybdate. Furthermore, to further increase the acidity of the resulting fruit juice fermented product, fruit juice may be added during fermentation, preferably in one or more divided additions after the logarithmic growth phase.

The fermented fruit juice of the present invention, obtained by fermenting a high-acidity fruit juice, is not particularly limited as long as it has a high acidity, but an acidity of 3.0% by weight or more is preferred, 5.0% by weight or more is more preferred, 7.0% by weight or more is even more preferred, and 9.0% by weight or more is particularly preferred. Furthermore, the flavor is improved compared to the fruit juice before fermentation due to the proliferation of yeast.

The ethanol concentration in the fruit juice fermentation product of the present invention is not particularly limited as long as it is low, but is preferably 1% by volume or less, more preferably 0.8% by volume or less, even more preferably 0.6% by volume or less, particularly preferably 0.4% by volume or less, and most preferably 0.2% by volume or less.Because it is a low-concentration ethanol fermentation product, it can be used in products other than alcoholic beverages and can be used in a wide range of foods.

Furthermore, the fermented fruit juice product of the present invention preferably contains isoamyl alcohol and/or phenethyl alcohol, and it is preferable that the amount of isoamyl alcohol and/or phenethyl alcohol is increased compared to before fermentation, with either one being at least 1.2 times the amount before fermentation, more preferably at least 1.3 times the amount, particularly preferably at least 1.5 times the amount, and most preferably at least 2 times the amount. By containing isoamyl alcohol and/or phenethyl alcohol, a floral flavor can be perceived, and it is thought that the flavor is improved compared to the fruit juice before fermentation.

The fermented fruit juice product of the present invention can be added to various foods and beverages, etc., to impart the flavor of high-acidity fruit juice, and is also expected to be used as a health food due to its high content of naturally occurring organic acids such as citric acid and malic acid. The amount added to various foods and beverages is not particularly limited, but is preferably 0.01 to 20% by weight, more preferably 0.05 to 10% by weight, and even more preferably 0.1 to 5% by weight. The foods and beverages to which the fermented fruit juice product can be added are not particularly limited, but the product can be used in beverages such as non-alcoholic beverages and alcoholic beverages, frozen desserts such as ice cream, fresh sweets such as jellies and yogurt, seasonings such as dressings and sauces, health foods, etc.

The present invention will be specifically explained below by showing examples, but the present invention is not limited to the following examples.

[Preparation 1]
Concentrated lemon juice (Preparation 1) was obtained by mixing 143 g of concentrated lemon juice (citric acid acidity: 31.8 wt %, Brix: 35°) and 357 g of tap water.

50 g of lemon juice from Preparation 1 was placed in a 200 mL baffled Erlenmeyer flask, and pre-cultured Metschnikowia agaves (NBRC10860 strain) was inoculated at 1% by volume. The mixture was then shaken and fermented at 30°C for 24 hours to obtain a lemon juice fermentation product (Example 1).
The preculture medium used was a sterilized liquid medium containing reduced starch syrup at a final concentration of 10% by weight and yeast extract at a final concentration of 2% by weight, in which the yeast was cultured with shaking at 30°C for 20 hours.

[Comparative Example 1]
Comparative products 1-1 to 1-3 were obtained in the same manner as in Example 1, except that Torulaspora delbrueckii (BIODIVA; manufactured by LALLEMAND) (Comparative Example 1-1), Saccharomyces cerevisiae (NBRC2346 strain) (Comparative Example 1-2), or Kluyveromyces lactis (NBRC1267 strain) (Comparative Example 1-3) was used as the yeast.

[Evaluation Test 1]
For Example Product 1, Preparation 1, and Comparative Products 1-1 to 1-3, pH, Brix (using a sugar refractometer), acidity (measured by neutralization titration and converted into citric acid), glucose concentration (F-kit D-glucose, manufactured by Roche), and ethanol concentration (F-kit Ethanol, manufactured by Roche) were measured and are shown in Table 1. Furthermore, for yeast growth, samples in which growth was observed were marked with an O, and samples in which growth was not observed were marked with an X. For Preparation 1, which is a high-acidity juice, the sum of acidity and sugar content is roughly measured as Brix, so the sugar content was calculated from Brix and acidity to calculate the sugar content/acidity ratio, and the results are shown in Table 1. Furthermore, for Example Product 1, Preparation 1, and Comparative Products 1 to 3, diluted 10-fold with tap water, were subjected to sensory evaluation. Those with a refreshing acidity or floral flavor were marked with an O, and those lacking this flavor were marked with an X. These results are shown in Table 1.

In Example 1, yeast growth was observed, and a high-acidity lemon juice fermented product was obtained, but yeast growth was not observed in Comparative Examples 1-1 to 1-3. There was no difference in acidity or ethanol concentration between Example Product 1, Preparation 1, and Comparative Products 1-1 to 1-3, and no change was observed due to the presence or absence of fermentation. However, the glucose concentration of Example Product 1 was lower than that of Preparation 1, which is thought to have decreased due to fermentation. Furthermore, Example Product 1 had a refreshing acidity as well as a floral flavor. The addition of the floral flavor resulted in a more pleasant, improved flavor in addition to the acidity, despite the high acidity. Therefore, it was found that a high-acidity fruit juice fermented product with improved flavor can be obtained by inoculating Metschnikowia agaves, which belongs to the genus Metschnikowia.

A fermented lemon juice product (Product 2) was obtained in the same manner as in Example 1, except that Metschnikowia pulcherrima FLAVIA (manufactured by LALLEMAND) was used as the yeast.

[Evaluation Test 2]
The Example Product 2 and the Preparation 1 were evaluated in the same manner as in Evaluation Test 1, and the aroma component concentrations were measured using gas chromatography (hereinafter referred to as GC) under the following measurement conditions. The results are shown in Table 2.

<GC measurement conditions>
Detector: FID (250°C)
Column: InertCap Pure-WAX
(ID: 0.25 mm x 30 m, df: 0.25 μm, manufactured by GL Science Co., Ltd.)
Column temperature: 40°C (held for 5 minutes) → heated at 10°C/min → 250°C (held for 3 minutes)
Carrier gas: Helium (100 kPa), 1.3 ml/min Injection temperature: 250°C
Internal standard: cyclohexanol. Sample: The sample was extracted with diethyl ether according to a conventional method.

Yeast growth was observed in Example 2, resulting in a highly acidic lemon juice fermented product. There was no difference in acidity or ethanol concentration between Example 2 and Preparation 1, and no change was observed with or without fermentation. However, the glucose concentration of Example 2 was lower than that of Preparation 1, presumably due to a decrease due to fermentation. Furthermore, Example 2 contained isoamyl alcohol and phenethyl alcohol, which are presumably produced by fermentation, and had a refreshing acidity as well as a floral flavor. The addition of the floral flavor resulted in a more pleasant, improved flavor in addition to the acidity, despite the high acidity. Therefore, it was found that a highly acidic fruit juice fermented product with improved flavor can be obtained by inoculating Metchnikowia pulcherrima, a species of the genus Metchnikowia.

[Preparation 2]
A concentrated reconstituted plum juice (Preparation 2) was obtained by mixing 33 g of concentrated plum juice (citric acid acidity: 18.5 wt %, Brix: 30°) and 67 g of tap water.

A fermented plum juice product (Product 3) was obtained in the same manner as in Example 1, except that Preparation 2, which is plum juice, was used instead of Preparation 1 and that Metschnikowia pulcherrima was used as the yeast.

[Evaluation Test 3]
Example Product 3 and Preparation 2 were evaluated in the same manner as in Evaluation Test 2. The results are shown in Table 3.

In Example 3, yeast growth was observed, and a highly acidic fermented plum juice product was obtained. There was no difference in acidity between Example 3 and Preparation 2, and no change was observed with or without fermentation. However, the glucose concentration of Example 2 was lower than that of Preparation 2, while the ethanol concentration was higher than that of Preparation 2. This suggests that fermentation reduced glucose and increased ethanol. Furthermore, Example 3 contains isoamyl alcohol and phenethyl alcohol, which are thought to be produced by fermentation, and has a refreshing acidity as well as a floral flavor. The addition of the floral flavor resulted in a more pleasant, improved flavor in addition to the acidity, despite the high acidity of the plum juice. Therefore, it was found that even with highly acidic plum juice, a highly acidic fermented juice product with improved flavor can be obtained by inoculating it with Metchnikowia pulcherrima, which belongs to the Metchnikowia genus.

[Test Example]
Concentrated lemon juice (citric acid acidity: 31.8 wt %, Brix: 35°) was diluted with tap water to prepare lemon juices of Test Example 1-1 (acidity 4.5 wt %, Brix 5°), Test Example 1-2 (acidity 9.1 wt %, Brix 10°), Test Example 1-3 (acidity 10.9 wt %, Brix 12°), and Test Example 1-4 (acidity 13.6 wt %, Brix 15). Furthermore, concentrated plum juice (citric acid acidity: 18.5 wt %, Brix: 30°) was diluted with tap water to prepare plum juices of Test Example 2-1 (acidity 3.1 wt %, Brix 5°), Test Example 2-2 (acidity 6.2 wt %, Brix 10°), Test Example 2-3 (acidity 9.3 wt %, Brix 15°), and Test Example 2-4 (acidity 12.4 wt %, Brix 15°). Except for using each of the prepared fruit juices, an attempt was made to obtain each fruit juice fermentation product by inoculating Metchnikowia pulcherrima, which belongs to the genus Metchnikowia, in the same manner as in Example 2. Furthermore, lemon juice of Test Example 1-5 (acidity 4.5% by weight, Brix 5°) and plum juice of Test Example 2-5 (acidity 3.1% by weight, Brix 5°) were prepared and inoculated with Torulaspora delbrueckii to attempt to obtain fermented juices of each.

[Evaluation Test 3]
After yeast inoculation, those in which yeast grew well were marked with a circle, those in which yeast grew slightly were marked with a triangle, and those in which yeast did not grow at all were marked with an x, and these are shown in Table 4. In addition, the pH and ethanol concentration were measured and are shown in Table 4. The Brix and acidity of each fruit juice at the time of yeast inoculation are also summarized in Table 4.

Yeast growth was observed in Test Examples 1-1 to 1-3 and 2-1 to 2-3, but no yeast growth was observed in Test Examples 1-4, 1-5, 2-4, and 2-5.
Test Examples 1-1 to 1-3 and 2-1 to 2-3 had an acidity of 4.5 to 10.9 wt %, and Test Examples 1-4 and 2-4 had an acidity of 12.4 wt % or more. Test Examples 1-5 and 2-5 used Torulaspora delbrueckii.
From the above, it is believed that there is a relationship between acidity and yeast growth, and it was found that by lowering the acidity at the start of fermentation to less than 12% by weight, highly acidic fruit juice can be fermented by yeast belonging to the genus Metschnikowia.

Claims (8)

A fermented fruit juice product having an acidity of 3.0% by weight or more and an ethanol concentration of 1.0% by volume or less, obtained by fermenting fruit juice containing citric acid and/or malic acid and having a sugar content of 5% by weight or less with a yeast belonging to the genus Metschnikowia that is capable of fermenting said fruit juice. The fermented fruit juice according to claim 1, wherein the fruit juice containing citric acid and/or malic acid is sour sweet orange juice or juice from a fruit belonging to the subgenus Prunus. 3. The fermented fruit juice product according to claim 1, wherein the content of isoamyl alcohol and/or phenethyl alcohol is increased compared to before fermentation. A method for producing a fermented fruit juice product having an acidity of 3.0% by weight or more and an ethanol concentration of 1.0 % by volume or less, obtained by inoculating a fruit juice containing citric acid and/or malic acid and having a sugar content of 5% by weight or less with a yeast belonging to the genus Metschnikowia that is capable of fermenting said fruit juice, and fermenting the fruit juice. The method according to claim 4 , wherein the pH at the time of inoculation with the yeast is 4.0 or less. 6. The method according to claim 4 or 5 , wherein the fruit juice containing citric acid and/or malic acid is a sour sweet orange juice or a fruit juice belonging to the subgenus Prunus. The method according to any one of claims 4 to 6 , wherein activated yeast is inoculated. A food or drink comprising the fermented fruit juice according to any one of claims 1 to 3 .