Method for producing packaged beverage containing ascorbic acid

Abstract

To provide a technique for suppressing discoloration over time of a packaged beverage containing ascorbic acid and having a pH of 5.0 to 8.0 while maintaining the flavor of the beverage.SOLUTION: The heat-sterilized packaged beverage according to the present invention contains ascorbic acid or salts thereof in an amount of 20 ppm or more and caffeine in an amount of 5 ppm or more, and is produced by a method including (1) a mixing step of adding sulfites to the beverage liquid in an amount such that the concentration of sulfur dioxide (SO2) is 1 to 30 ppm, (2) a pH adjusting step of adjusting the pH of the beverage liquid to 5.0 to 8.0, and (3) a filling step of filling the beverage liquid in a package.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing a packaged beverage containing ascorbic acid. [Background technology]

[0002] In foods and beverages that are stored for long periods, color changes over time can cause significant psychological anxiety to consumers, so preventing the appearance, or discoloration of foods and beverages, is an important issue in preserving and improving the quality of foods and beverages. One cause of discoloration in foods and beverages is the oxidation of food components. Therefore, food additives such as antioxidants are used to prevent oxidation, and ascorbic acid (vitamin C) is often used in packaged beverages due to its excellent antioxidant properties and water solubility.

[0003] However, ascorbic acid is known to brown in aqueous solution due to its own oxidation and decomposition. Furthermore, ascorbic acid is prone to undergo Maillard reactions with amino acids, peptides, proteins, etc., resulting in significant browning due to this Maillard reaction (Non-Patent Document 1). Therefore, methods for inhibiting the browning of ascorbic acid itself have also been proposed. For example, there is a method for preventing the browning of ascorbic acid or its derivatives by incorporating a flavonoid glycoside such as rutin (Patent Document 1), and a method for preventing browning by adding sodium sulfite to a beverage containing sugars and ascorbic acids (Patent Document 2). Furthermore, Patent Document 3 describes a method for stabilizing ascorbic acid by adding sulfite to a liquid formulation containing reducing sugars and taurine. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 4-99771 [Patent Document 2] Japanese Patent Application Publication No. 8-256744 [Patent Document 3] Japanese Patent Application Laid-Open No. 2008-179553 [Non-patent literature]

[0005] [Non-Patent Document 1] Journal of the Agricultural Chemical Society of Japan, Vol. 50, No. 10, pp. 209-216, 1976 Summary of the Invention [Problem to be solved by the invention]

[0006] It is known that the browning of an aqueous solution of ascorbic acid increases at pH 5.0, and the browning becomes particularly pronounced as the solution becomes more alkaline (Non-Patent Document 1).

[0007] An object of the present invention is to provide a method for producing a packaged beverage that contains ascorbic acid and has a pH of 5.0 to 8.0, but that is inhibited from discoloring during storage and has a good flavor. [Means for solving the problem]

[0008] As a result of extensive research to solve the above problems, the present inventors have found that sulfite is effective in inhibiting browning in an aqueous ascorbic acid solution at a nearly neutral pH range of 5.0 to 8.0. They have also found that caffeine can reduce the off-taste caused by sulfite, which is significantly perceived in the nearly neutral range. This led to the completion of the present invention.

[0009] That is, but not limited to, the present invention relates to the following: [1] A method for producing a heat-sterilized packaged beverage containing 20 ppm or more of ascorbic acid or a salt thereof and 5 ppm or more of caffeine, (1) a mixing step of adding sulfite to a beverage liquid in an amount that results in a sulfur dioxide (SO2) concentration of 1 to 30 ppm; (2) a pH adjustment step of adjusting the pH of the beverage liquid to 5.0 to 8.0; and (3) a filling step of filling the beverage liquid into a container; The above method, comprising: [2] The method according to [1], wherein the packaged beverage contains 60 to 1000 ppm of ascorbic acid or a salt thereof and 5 to 30 ppm of caffeine. [3] The method according to [1] or [2], wherein the packaged beverage is a beverage containing tea leaf extract. [4] The drinking liquid is (a) and (b) of the following: (a) Carbohydrate content in beverages: Less than 0.5g / 100ml (b) Protein content in beverages: Less than 0.5g / 100ml The method according to any one of [1] to [3], which satisfies at least one of the above. [5] The method according to any one of [1] to [4], wherein the sulfite compound is potassium pyrosulfite. [6] The method according to any one of [1] to [5], wherein the container is a PET container. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a packaged beverage that contains ascorbic acid but is inhibited from discoloring due to browning of the ascorbic acid itself, and has a good flavor and is in a substantially neutral pH range. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a graph showing the change in color tone (ΔE) over time of an ascorbic acid-containing beverage (Experiment 2-2). [Figure 2] FIG. 2 is a graph showing the change in pH over time of the ascorbic acid-containing beverage (Experiment 2-2). [Figure 3] FIG. 3 is a graph showing the change in color tone (ΔE) over time of a green tea beverage (Experimental Example 3). [Figure 4] FIG. 4 shows photographs showing the change in color tone of a green tea drink over time (Experimental Example 3, top: control drink, bottom: test drink). DETAILED DESCRIPTION OF THE INVENTION

[0012] The beverage of the present invention is described below. Unless otherwise specified, "ppm" used in this specification refers to ppm by weight / volume (w / v). Furthermore, unless otherwise specified, numerical ranges are expressed as including their endpoints.

[0013] Mixing process The beverage of the present invention contains ascorbic acid or a salt thereof. In the present invention, a sulfite is added to the beverage liquid of the beverage containing ascorbic acid or a salt thereof to suppress discoloration of the beverage due to browning of ascorbic acid.

[0014] The ascorbic acid or a salt thereof (also simply referred to as "ascorbic acid") used in the present invention is not particularly limited as long as it is suitable for use in beverages. Specific examples include ascorbic acid, sodium ascorbate, potassium ascorbate, and calcium ascorbate, with L-ascorbic acid being particularly preferred. When blending ascorbic acid into beverages, an ascorbic acid preparation may be added, or ascorbic acid contained in raw materials such as fruit juice may be used. In a preferred embodiment, L-ascorbic acid commercially available as a food additive is used.

[0015] In the present invention, ascorbic acid or a salt thereof is added so that the ascorbic acid concentration in the beverage is 20 ppm or higher. It is preferably 40 ppm or higher, more preferably 60 ppm or higher or 80 ppm or higher, even more preferably 100 ppm or higher, particularly preferably 150 ppm or higher, and may be 200 ppm or higher. The upper limit of the ascorbic acid concentration is not particularly limited, but from the viewpoint of maintaining a good flavor of the beverage, it is usually 1000 ppm or lower, preferably 800 ppm or lower, more preferably 600 ppm or lower, even more preferably 500 ppm or lower, and particularly preferably 400 ppm or lower. The ascorbic acid concentration can be measured by a method known to those skilled in the art, such as by using HPLC (high-performance liquid chromatography), and is calculated as the sum of the contents of ascorbic acid (reduced form) and dehydroascorbic acid (oxidized form).

[0016] In the present invention, browning caused by ascorbic acid in packaged beverages can be suppressed by adding a sulfite to the beverage liquid. The type of sulfite used in the present invention is not limited, and any sulfite that can be used as a food additive in accordance with the laws of each country may be selected. Specific examples include sodium sulfite, sodium hyposulfite, sulfur dioxide, potassium metabisulfite, and sodium metabisulfite, with potassium metabisulfite being particularly preferred in terms of flavor.

[0017] The amount of sulfite to be added is calculated so that the sulfur dioxide (SO2) concentration in the beverage is 1 to 30 ppm. Here, "as sulfur dioxide concentration" means "converted into the concentration of sulfur dioxide generated when sulfite dissociates." For example, the amount of sulfite to be added can be calculated using the following chemical formula: (Potassium pyrosulfite) K2S2O5 → K2O + 2SO2 (Sodium pyrosulfite)Na2S2O5 →Na2SO3 + SO2 (Sodium sulfite)Na2SO3+2H+→2Na++H2O+SO2 Sulfite is more preferably added so that the concentration of sulfur dioxide in the beverage is 1 to 30 ppm or 2 to 25 ppm, and even more preferably 3 to 20 ppm or 4 to 20 ppm.

[0018] The effects of the present invention can be significantly achieved by adding sulfite in an amount of about 0.07 to 0.6 times the amount of ascorbic acid added. The amount of sulfite added is preferably 0.1 times or more, more preferably 0.2 times or more, and even more preferably 0.3 times or more, the amount of ascorbic acid added.

[0019] Sulfites are typically used in foods and beverages with high fat and protein content to prevent deterioration associated with oxidation, primarily in fats and oils, and spoilage (putrefaction) in protein and carbohydrate foods. However, because the flavor (off-flavor) of sulfites themselves impairs the original flavor of the beverage, sulfites are not typically added to beverages that do not contain fats, oils, proteins, or carbohydrates, such as soft drinks. Furthermore, if the beverage is acidic (pH less than 4.5), the off-flavor of sulfites tends to be reduced by the acidity, but if the beverage is approximately neutral, the off-flavor of sulfites is noticeable and may alter the beverage's flavor.

[0020] The present invention targets nearly neutral beverages that are susceptible to the browning caused by ascorbic acid and the off-taste of sulfites. Here, "nearly neutral" refers to a pH of 5.0 to 8.0. A preferred embodiment of the present invention is a beverage that typically causes the off-taste of sulfites, i.e., a beverage that does not contain at least one of fats and oils, proteins, and carbohydrates. "Not containing fats and oils, proteins, or carbohydrates" means that the content of these components in the beverage is less than 0.5 g / 100 ml. The beverage obtained by the present invention has a good flavor with reduced off-flavors derived from sulfite, even in a nearly neutral pH range. In view of the remarkable effects of the present invention, a beverage in which the liquid beverage satisfies at least one of the following requirements (a) and (b) is an example of a preferred embodiment of the present invention. (a) Carbohydrate content in beverages: Less than 0.5g / 100ml (b) Protein content in beverages: Less than 0.5g / 100ml Furthermore, the beverage according to the present invention preferably has a lipid content of less than 0.5 g / 100 ml.

[0021] The beverage obtained by the present invention has a good flavor with reduced off-flavors derived from sulfites, even in the approximately neutral range. In the present invention, the off-flavors derived from sulfites can be reduced by adding caffeine. In the present invention, caffeine is added so that the caffeine concentration in the beverage is 5 ppm or higher. To achieve a more pronounced effect, the caffeine concentration is preferably 6 ppm or higher, more preferably 7 ppm or higher, and even more preferably 8 ppm or higher. The upper limit of caffeine can be appropriately set taking into account the flavor and taste of the beverage, but is typically 60 ppm or lower, preferably 50 ppm or lower, more preferably 40 ppm or lower, even more preferably 30 ppm or lower, and particularly preferably 25 ppm or lower or 20 ppm or lower.

[0022] The caffeine used in the present invention may be a monohydrate (CH) obtained by synthesis or the like. 10 N4O2·H2O) or anhydrous (anhydrous caffeine, C8H 10 Caffeine-containing plant extracts can be used either directly or in concentrated or purified form, i.e., caffeine-containing plant extracts obtained by selectively removing components other than caffeine from the caffeine-containing plant extract. Caffeine-containing plant extracts are produced by extracting coffee beans, cola nuts, tea leaves, cacao, etc. with a solvent such as water or hot water, methanol, ethanol, isopropanol, or ethyl acetate.

[0023] As already mentioned, in the present invention, browning caused by ascorbic acid is inhibited by the use of sulfite compounds, and the effect of sulfite compounds on flavor is reduced by the use of caffeine. In addition, in beverages containing tea leaf extract, caffeine can also prevent discoloration (darkening) caused by catechins contained in the tea leaf extract. In other words, beverages containing tea leaf extract are one of the preferred embodiments of the present invention, as they can further benefit from the effect of the present invention, namely, prevention of discoloration of the liquid color.

[0024] Specifically, beverages containing tea leaf extract are beverages containing an extract from tea leaves of the tea plant (scientific name: Camellia sinensis), and include green tea beverages, black tea beverages, oolong tea beverages, etc. The content of catechins in beverages containing tea leaf extract is, for example, 50 to 1500 ppm, preferably 100 to 1400 ppm, more preferably 200 to 1300 ppm, and even more preferably 300 to 1200 ppm. In the present invention, catechins collectively refer to catechin, epicatechin, gallocatechin, epigallocatechin, catechin gallate, epicatechin gallate, gallocatechin gallate, and epigallocatechin gallate, and the catechin content is defined based on the total amount of the above eight types. The content of catechins in a beverage can be measured using high-performance liquid chromatography (HPLC) or the like.

[0025] pH adjustment process The present invention targets beverages in a nearly neutral pH range, which are typically susceptible to the browning of ascorbic acid and the unpleasant taste of sulfites. Here, the term "nearly neutral" as used herein refers to a pH range of 5.0 to 8.0. In a preferred embodiment, the beverage of the present invention preferably has a pH of 5.3 to 7.5 or 5.5 to 7.3, more preferably 5.6 to 7.0, and even more preferably 5.7 to 6.8 or 5.7 to 6.5. It is known that beverages adjusted to a pH of approximately 5.0 to 6.5 gradually decrease in pH during storage, resulting in an increased sourness. The ascorbic acid-containing beverage of the present invention, to which sulfite has been added, has the advantages of not only inhibiting browning during storage but also reducing pH changes during storage.

[0026] The production method of the present invention includes a step of adjusting the pH of the beverage liquid to the above range using a pH adjuster. As the pH adjuster, one or more of sodium bicarbonate, potassium carbonate, sodium hydroxide, and the like, which are approved as food additives, can be used. The amount of pH adjuster added can be determined depending on the type of pH adjuster so as to achieve the desired pH.

[0027] The pH adjusting step according to the present invention may be carried out separately from the mixing step, or may be carried out simultaneously with the mixing step for preparing the beverage liquid.

[0028] Heat sterilization In the present invention, the beverage liquid is heat sterilized for long-term storage at room temperature. Heat sterilization can be performed using conventional techniques, and can be appropriately selected from methods such as filling the beverage liquid into a container and then heat sterilizing (such as retort sterilization), or sterilizing the beverage liquid before filling it into a container. For example, when the container is a PET bottle, a paper carton, a bottled beverage, or a pouch beverage, the beverage liquid can be subjected to FP or UHT sterilization, in which the beverage liquid is held at, for example, 90 to 130°C for one to several tens of seconds, and then filled in a predetermined amount. Furthermore, in the case of a can container, the beverage liquid can be filled in a predetermined amount into the can container, and then sterilized together with the container (for example, at 85°C for 10 minutes).

[0029] Filling process The present invention relates to a packaged beverage that can be stored for a long period of time at room temperature, and is produced by filling a beverage liquid into a container. Here, packaged beverages refer to beverages that are packaged in a container and sealed, and include RTD beverages (RTD = Ready To Drink: beverages packaged in PET bottles, cans, glass bottles, paper bottles, etc., that can be consumed immediately after opening the lid). The beverages of the present invention also include beverages for dilution, such as RTS beverages (RTS = Ready To Serve: beverages that can be poured into a glass with the lid opened, diluted with water or soda water, etc.). There are no particular limitations on the containers used for packaged beverages, and examples include plastic containers such as polyethylene terephthalate (PET), metal cans such as aluminum cans and steel cans, paper containers, and glass bottles. The content volume of the packaged beverage is not particularly limited, but is, for example, 50 mL to 3000 mL, preferably 100 mL to 2000 mL or 200 mL to 1000 mL.

[0030] Generally, PET bottles are one of the containers that are susceptible to environmental factors (heat, light, oxygen, etc.) and tend to discolor beverages, but the present invention can effectively prevent discoloration of beverages over time. PET bottle containers are an example of a preferred embodiment of the present invention, as they can greatly benefit from the effects of the present invention.

[0031] From one perspective, the present invention is a method for suppressing discoloration of a beverage caused by ascorbic acid, and from another perspective, the present invention is a method for reducing the effect of sulfites on the flavor of a beverage while suppressing discoloration of a beverage caused by ascorbic acid. [Example]

[0032] The present invention will be specifically described in detail below by showing experimental examples, but the present invention is not limited to these examples. In the experiments below, L-ascorbic acid (food additive) was used as the ascorbic acid, potassium pyrosulfite (food additive) was used as the sulfite, and sodium bicarbonate (sodium bicarbonate, food additive) was used as the pH adjuster.

[0033] Experimental Example 1 The ingredients shown in the table below were mixed with water (90°C) to prepare a total volume of 1 L of aqueous solution, and 500 mL each was filled into PET containers (sulfur dioxide concentration of samples 1-3 and 1-4: approximately 17 ppm). All packaged beverages had a carbohydrate content, protein content, and lipid content of 0 g / 100 mL.

[0034] The stability of the packaged beverage was evaluated by storing it in an incubator set at 55°C. Stability was evaluated by visually determining the degree of coloration before storage (D0), on the 7th day (D7), the 14th day (D14), and the 21st day (D21) of storage.

[0035] As is clear from the results shown in the table below, aqueous ascorbic acid solutions tend to become discolored at high pH levels, but it was confirmed that sulfite effectively inhibits discoloration.

[0036] [Table 1]

[0037] Experimental Example 2 Experiment 2-1 Caffeine was added to the beverage (D0) of Sample 1-4 in Experimental Example 1 as a control to the concentrations shown in the table below, and the beverage was heat sterilized (130°C, 5 minutes), and then 500 mL of the beverage was filled into PET containers to produce packaged beverages. The sulfur dioxide concentration in the packaged beverage was approximately 2 ppm, and the carbohydrate, protein, and lipid contents were 0 g / 100 ml.

[0038] After storing the beverages at 55°C for 14 days, they were cooled to 20°C and subjected to a flavor evaluation by a panel of five experts. Caffeine-free and caffeinated beverages were presented in pairs, and each panelist used a two-point discrimination test to determine which of the presented beverages did not have an unpleasant sulfite-derived flavor.

[0039] As is clear from the results in the table below, in a beverage with a pH of 6.5, the flavor derived from sulfites was perceived as an off-taste, but adding 5 ppm or more of caffeine reduced this off-taste. Furthermore, in the sample with 50 ppm of caffeine added, the flavor of the caffeine itself was clearly detectable.

[0040] [Table 2-1]

[0041] Experiment 2-2 The ingredients shown in the table below were mixed with water to prepare a 1 L solution, which was then heat sterilized at 136°C for 30 seconds and filled into PET bottles to produce packaged beverages containing ascorbic acid. The sulfur dioxide concentrations of Samples 2-2 to 2-6 were 16 to 25 ppm, and the carbohydrate, protein, and lipid contents of all the beverages were 0 g / 100 ml.

[0042] [Table 2-2]

[0043] (1) Color Tone Evaluation Samples 2-1 and 2-2 were stored in an incubator set at 55°C, and the color tone of the packaged beverages was evaluated. Using a spectrophotometer (Color Meter ZE-2000, manufactured by Nippon Denshoku Industries Co., Ltd.), the samples were placed in quartz cells with a 10 mm optical path length, and the L, a, and b values ​​of the Lab color system were measured by the transmission method (the light receiving conditions of the colorimeter conformed to JIS Z 8722). The color difference (ΔE) was calculated by subtracting the Lab value before storage (D0) from the Lab value after 14 days of storage at 55°C (D14), as shown in the following formula:

[0044]

number

[0045] The ΔE value is the color difference between two colors, and the larger this value, the greater the change in color tone. As is clear from the results shown in Figure 1, adding sulfite to a nearly neutral beverage containing ascorbic acid significantly reduced the color tone change (ΔE: 11.6 for Sample 2-1, ΔE: 6.1 for Sample 2-2). This change was also visible to the naked eye.

[0046] (2) pH change Samples 2-1 and 2-2 were stored in an incubator set at 55°C for 28 days, and the changes in pH of the packaged beverages were evaluated. As is clear from the results shown in Figure 2, the pH of nearly neutral beverages containing ascorbic acid decreases during storage, but it was suggested that the addition of sulfite could alleviate this decrease in pH.

[0047] (3) Flavor evaluation Samples 2-2 to 2-6 were stored at 55°C for 14 days, then cooled to 20°C and evaluated for flavor by a five-person expert panel. A caffeine-free beverage (Sample 2-2) was presented in pairs with a caffeinated beverage, and each panelist performed a two-point discrimination test to determine which of the paired beverages they perceived as having no off-flavor derived from sulfites. The results are shown in the table below. Even in beverages with a pH of around 6.0, the sulfite-derived flavor was perceived as an off-flavor, but the off-flavor could be reduced by adding 5 ppm or more of caffeine.

[0048] [Table 2-3]

[0049] Experimental Example 3 (Green Tea Drink) A green tea beverage was prepared using a caffeine-containing green tea extract to confirm the effects of the present invention. First, 20 g of green tea leaves (low-grade sencha) were extracted with 1000 mL of hot water (70-80°C) for 5 minutes, and the tea leaves were separated. The extract was then passed through a 200-mesh sieve to remove solids such as ground tissue and tea particles. Water was then added to the resulting liquid to make the concentration 47.5 mg / 100 mL to prepare a green tea extract. The caffeine content of the green tea extract was 12 ppm, and the catechin content was 420 ppm.

[0050] Next, 250 ppm of L-ascorbic acid and 150 ppm of potassium pyrosulfite were mixed with this green tea extract, and the pH was adjusted to 6.4 with 290 ppm of sodium bicarbonate. This beverage was then heat sterilized at 125°C for 7 minutes, and 500 mL of each was filled into PET containers to produce a packaged beverage (test beverage, Sample 3-2, sulfur dioxide concentration: approximately 14 ppm). A control beverage (control beverage, Sample 3-1) was prepared in the same manner, except that the ascorbic acid concentration was 320 ppm and potassium pyrosulfite was not added. The carbohydrate, protein, and lipid contents of both the test and control beverages were less than 0.5 g / 100 ml.

[0051] (1) Color Tone Evaluation The test beverages and control beverages were stored in an incubator set at 55°C to evaluate their stability (change in color over time). The color of the beverages was evaluated by measuring the color difference (ΔE) in the same manner as in Experimental Example 2, and visually assessing the liquid color (degree of browning) of the beverages before storage (D0), on the 7th day (D7), the 14th day (D14), the 21st day (D21), and the 25th day (D25) of storage. Generally, the following is known about color difference (ΔE):

[0052]

number

[0053] The evaluation results are shown in the table below and Figure 3. As is clear from the photograph of the green tea beverage (Figure 4), the beverage (Sample 3-2) manufactured with the addition of sulfite (potassium pyrosulfite) effectively inhibited not only the browning caused by ascorbic acid but also the darkening caused by catechins, maintaining a vivid green color. The control beverage (Sample 3-1) without added sulfite had a ΔE of 16.6, and the photograph also shows that it was a different color system. On the other hand, the test beverage (Sample 3-2) with added sulfite had a ΔE of 5.7, and although there was a color change during storage, the change was clearly minimal.

[0054] [Table 3]

[0055] (2) pH and flavor evaluation The test and control beverages were stored at 55°C for 25 days, and the changes in pH of the green tea beverages were measured. The pH of both beverages decreased after storage. The degree of decrease was -0.18 for the control beverage, while the test beverage was less pronounced at -0.09. It is known that a pH change of 0.1 significantly affects the color and flavor of tea beverages. A panel of five experts evaluated the flavor of the stored green tea beverages. Compared to the test beverage, the control beverage was rated as having a sour taste and a weaker aroma, which is undesirable for a green tea beverage.

[0056] Experimental Example 4 (Oolong tea drink) An oolong tea beverage (caffeine content: 20 ppm, catechin content: 200 ppm) was prepared in the same manner as in Experimental Example 3, except that oolong tea leaves were used instead of green tea leaves, and the effects of the present invention were confirmed. The oolong tea beverage was prepared by mixing oolong tea extract with 300 ppm L-ascorbic acid and 100 ppm potassium pyrosulfite, and adjusting the pH to 6.0 with sodium bicarbonate. This beverage was heat sterilized at 136°C for 30 seconds, and then 500 mL aliquots were filled into PET containers to produce packaged beverages (sulfur dioxide concentration of the test beverage: approximately 22 ppm). When the color and flavor changes were evaluated using a beverage without added potassium pyrosulfite as a control, it was found that the addition of sulfite also suppressed changes in appearance (browning) during storage and the development of sourness in the oolong tea beverage.

[0057] Experimental Example 6 (Tea Drink) Experimental Example 3 was repeated, except that the green tea leaves were replaced with black tea leaves (decaffeinated Darjeeling) decaffeinated using supercritical carbon dioxide extraction. Three types of black tea beverages (caffeine content: 2 ppm, catechin content: 80 ppm) were prepared to confirm the effectiveness of the present invention. Three types of black tea beverages were prepared: decaffeinated black tea extract mixed with 300 ppm L-ascorbic acid and 100 ppm potassium pyrosulfite and adjusted to pH 5.8 with sodium bicarbonate (Test Beverage 6-1); test beverage 6-2 with caffeine added to a test beverage with a caffeine content of 10 ppm; and control beverage mixed with 300 ppm L-ascorbic acid and adjusted to pH 5.8 with sodium bicarbonate (Control Beverage). These beverages were heat sterilized at 136°C for 30 seconds, and then 500 mL of each was filled into PET containers to produce packaged beverages (sulfur dioxide concentrations of Test Beverages 6-1 and 6-2: 18-23 ppm). The test beverages showed less change in appearance (browning) and less sourness during storage than the control beverage. Furthermore, compared to test beverage 6-1, which contained a low concentration (2 ppm) of caffeine, test beverage 6-2, which contained 10 ppm of caffeine, exhibited less perceived sourness after storage and less noticeable off-flavors of sulfites, demonstrating superior flavor.

[0058] Experimental Example 7 (Green Tea Drink) Green tea extract was added with water to produce a green tea extract with a Brix of 3.0 (caffeine content: 190 ppm, catechin content: 3850 ppm). 1000 ml of this liquid was mixed with 0.5 g of matcha, 1.5 g of L-ascorbic acid, and 0.5 g of potassium pyrosulfite, and then 1.1 g of sodium bicarbonate was added to adjust the pH to 6.0. 190 ml of this beverage was filled into cans and sterilized by heating at 125°C for 15 minutes. A control beverage without added potassium pyrosulfite was also prepared. These beverages were stored at 55°C for 14 days, then opened, poured into glasses, and diluted with 15 times the amount of water. The color of the liquid was visually confirmed and a flavor evaluation was performed. The test beverages containing added potassium metabisulfite maintained their bright green color and suppressed the development of sourness.

Claims

1. A method for producing a heat-sterilized packaged beverage containing 20 ppm or more of ascorbic acid or a salt thereof and 5 ppm or more of caffeine, Sulfur dioxide (SO ２ a mixing step of adding sulfite to the beverage liquid in an amount such that the concentration of sulfite is 1 to 30 ppm; a pH adjustment step of adjusting the pH of the beverage liquid to 5.0 to 8.0; and a filling step of filling the beverage liquid into a container; The above method, comprising:

2. The method according to claim 1, wherein the packaged beverage contains 60 to 1000 ppm of ascorbic acid or a salt thereof and 5 to 30 ppm of caffeine.

3. The method according to claim 1, wherein the packaged beverage is a beverage containing tea leaf extract.

4. The beverage comprises the following (a) and (b): (a) Carbohydrate content in the beverage: less than 0.5 g / 100 ml (b) Protein content in the beverage: Less than 0.5g / 100ml The method according to claim 1, wherein at least one of the following is satisfied:

5. 2. The method of claim 1, wherein the sulfite compound is potassium pyrosulfite.

6. The method of claim 1 , wherein the container is a PET container.

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