Fermented guava leaf composition having enhanced antioxidant efficacy by using lactic acid bacteria, and preparation method therefor

Abstract

The present invention relates to a method for preparing a fermented guava leaf composition having antioxidant efficacy superior to that of conventional guava leaves by using lactic acid bacteria fermentation in a guava leaf extract. The present invention has an excellent effect of providing: the method for preparing a guava leaf composition fermented with lactic acid bacteria, in which lactic acid bacteria of Leuconostoc mesenteroides (MGE 3138), Lactobacillus plantarum (MGE 3143), and Leuconostoc citrium Cares-1 are inoculated into a guava leaf extract and fermented; and a food composition having improved antioxidant efficacy and palatability by using the composition.

Description

Fermented guava leaf composition with enhanced antioxidant efficacy using lactic acid bacteria and method for preparing the same

[0001] This specification claims the benefit of the filing date of Korean Patent Application No. 10-2024-0201710 filed with the Korean Intellectual Property Office on December 31, 2024, the entire contents of which are incorporated into the present invention.

[0002] This invention is research conducted under the support of the National Research Foundation of Korea-2024 Industry-Academic Joint Technology Development Project, funded by the Korean government (Ministry of Education) from May 2024 to December 31, 2024 (Project No.: 1345370649).

[0003] The present invention relates to a guava leaf fermentation composition with enhanced antioxidant efficacy obtained by fermenting a guava leaf extract with lactic acid bacteria and a method for preparing the same. More specifically, the invention relates to a food composition with enhanced antioxidant efficacy containing a guava leaf fermentation composition obtained by inoculating and fermenting a guava leaf extract with lactic acid bacteria as an active ingredient, and a method for preparing the same.

[0004]

[0005] Guava (Psidium guajava) is a tropical tree belonging to the Myrtaceae family, widely cultivated in tropical and subtropical regions around the world, and is known as Guava or Kuawa. Guava leaves contain large amounts of various compounds such as limonene, β-pinene, α-pinene, rutin, flavonoids, quercetin, saponin, tannin, luteolin, camperol, and guarbolide, as well as bioactive substances such as triterpenes, alkaloids, carotenoids, vitamins, lecithin, and glycosides. For this reason, research on the pharmacological efficacy of guava has been conducted for a long time, and currently, guava extract is widely used in areas such as the management of health problems like skin diseases and diarrhea. Research on the functional properties of guava is actively underway in areas such as the quality characteristics of milk tea with added fermented guava leaves, the quality characteristics of cookies with added guava leaf powder, and the antioxidant activity of guava leaf extracts and methanol fractions obtained using column chromatography.

[0006] Lactic acid bacteria are representative microorganisms used as probiotics and have been widely utilized in fermented foods such as kimchi, dairy products, and brewed foods, as well as in the pharmaceutical and feed industries. They are known for their benefits, including preventing diarrhea, maintaining normal intestinal flora, boosting immunity, anticancer effects, and lowering blood cholesterol. Furthermore, lactic acid bacteria are known to possess antioxidant activity capable of protecting themselves from reactive oxygen species (ROS). Unlike regular oxygen, ROS are unstable oxygen molecules possessing unpaired electrons, making them the most common radicals generated within the human body. The accumulation of ROS in the body poses a significant problem, as it can lead to various diseases such as cancer, liver cirrhosis, and arthritis. To prevent this, numerous studies on antioxidants are being conducted. Antioxidants are compounds that inhibit the action of free radicals and can prevent various diseases caused by ROS. The antioxidant effects of lactic acid bacteria are known to result from the complex interplay of metal ion chelating, scavenging of reactive oxygen species, and reduction reactions.

[0007] Prior art related to the present invention includes Korean Registered Patent No. 10-1874456, which relates to a method for preparing a guava leaf fermented metabolite and a guava leaf fermented metabolite composition for improving symptoms of atopic dermatitis, and Korean Registered Patent No. 10-0836458, which relates to a method for preparing a functional food using guava.

[0008] However, to date, no technology has been disclosed regarding the enhancement of antioxidant efficacy by inoculating guava leaf extract with lactic acid bacteria and fermenting it.

[0009]

[0010] The objective of the present invention is to provide a guava leaf lactic acid bacteria fermentation composition capable of enhancing antioxidant efficacy by inoculating lactic acid bacteria into guava leaf juice.

[0011] Another objective of the present invention is to provide a food composition containing the guava leaf lactic acid bacteria fermentation composition as an active ingredient, with enhanced antioxidant and sensory efficacy.

[0012]

[0013] To achieve the objective of the above-mentioned problem, the present invention provides a method for preparing a guava leaf fermentation composition with enhanced antioxidant efficacy, comprising the steps of: (1) preparing an extract of guava leaves; and (2) inoculating the extract of the step with lactic acid bacteria to ferment it.

[0014] In addition, the present invention provides a guava leaf fermentation composition prepared by the above method.

[0015] In addition, the present invention provides a food composition comprising a guava leaf fermentation composition prepared by the above method.

[0016]

[0017] The guava leaf fermentation composition prepared by the above method exhibits superior antioxidant efficacy compared to the guava leaf extract before fermentation through lactic acid bacteria fermentation, and because it uses only natural substances, it has no side effects such as toxicity to the human body, making it effective for use as a material for health functional foods.

[0018]

[0019] Figure 1 is a process diagram showing a method for preparing a lactic acid bacteria fermentation composition of guava leaf extract according to the present invention.

[0020] Figure 2 is a graph showing the ABTS radical scavenging ability of the guava leaf lactic acid bacteria fermentation composition according to the present invention.

[0021] Figure 3 is a graph showing the DPPH radical scavenging ability of the guava leaf lactic acid bacteria fermentation composition according to the present invention.

[0022] Figure 4 is a graph showing the total polyphenol content of the guava leaf lactic acid bacteria fermentation composition according to the present invention.

[0023] Figure 5 is a graph showing the total flavonoid content of the guava leaf lactic acid bacteria fermentation composition according to the present invention.

[0024]

[0025] The present invention aims to provide a method for preparing a guava leaf fermentation composition with enhanced antioxidant efficacy using lactic acid bacteria, and a guava leaf fermentation composition using the same method.

[0026] Specifically, the present invention provides a guava leaf fermentation composition prepared by inoculating a guava leaf extract with lactic acid bacteria and then fermenting it, and a food composition with enhanced antioxidant efficacy containing the same as an active ingredient.

[0027] The present invention is a method for providing a guava leaf fermentation composition comprising the following steps.

[0028] (a) a step of obtaining a guava leaf extract by adding guava leaves to purified water and heating;

[0029] (b) a step of cooling the guava leaf extract produced in step (a) above;

[0030] (c) A step of filtering the guava leaf extract cooled in step (b) above;

[0031] (d) A step of pasteurizing the guava leaf extract filtered in step (c) above;

[0032] (e) a step of inoculating lactic acid bacteria into the guava leaf extract sterilized in step (d) above; and,

[0033] (f) A step of fermenting the guava leaf extract inoculated with lactic acid bacteria in step (e) above in a culture medium.

[0034] As an embodiment of the invention, the guava leaves of step (a) may be 1 to 20 weight %, specifically 3 to 17 weight %, and more specifically 5 to 15 weight %.

[0035] As one embodiment of the invention, the distilled water in step (a) may be 80 to 99 weight %, specifically 83 to 97 weight %, and more specifically 85 to 95 weight %.

[0036] As one embodiment of the invention, the yield of the guava leaf extract in step (a) may be 80 to 90%, specifically 82 to 87%, and more specifically 85%.

[0037] As an embodiment of the invention, in step (b), the temperature at which the guava leaf extract is cooled may be 20 to 30 ℃, specifically 22 to 27 ℃, more specifically 25 ℃, but is not limited thereto, and more specifically, may be cooled at room temperature.

[0038] As an embodiment of the invention, in step (b), the time for cooling the guava leaf extract may be 4 to 8 hours at room temperature, specifically 5 to 7 hours at room temperature, and more specifically 6 hours at room temperature.

[0039] As an embodiment of the invention, in step (c), the filtration of the guava leaf extract may be performed using one or more materials selected from the group consisting of cotton cloth, filter paper, microfilter paper, glass fiber filter paper, nanofilter paper, ceramic filter, membrane filter, sponge filter, and activated carbon filter, specifically, the filtration may be performed using one or more materials selected from the group consisting of cotton cloth, filter paper, membrane filter, and sponge filter, and more specifically, the filtration may be performed using cotton cloth and filter paper.

[0040] As an embodiment of the invention, in step (c), the filtration of the guava leaf extract may be leaf residue.

[0041] As an embodiment of the invention, in step (d), the temperature of pasteurization of the extract may be 55 to 75 ℃, specifically 58 to 70 ℃, and more specifically 60 to 68 ℃.

[0042] As an embodiment of the invention, in step (d), the pasteurization time of the extract may be 10 to 60 minutes, specifically 20 to 40 minutes, and more specifically 30 minutes.

[0043] As an embodiment of the invention, in step (e), the lactic acid bacteria may be one or more strains selected from the group consisting of strains of the genus Leuconostoc sp., Bifidobacterium sp., Streptococcus sp., Enterococcus sp., Peptostreptococcus sp., and Lactobacillus sp., specifically, one or more strains selected from the group consisting of strains of the genus Leuconostoc and Lactobacillus, and more specifically, Leuconostoc mesenteroides (MGE 3138), Lactobacillus plantarum (MGE 3143), and Leuconostoc citrium cares-1. Cares-1) is.

[0044] As an embodiment of the invention, in step (e), the amount of lactic acid bacteria inoculated may be 0.1 to 3 weight% relative to the guava leaf extract, specifically 0.5 to 2.5 weight%, and more specifically 1 to 2 weight%.

[0045] As one embodiment of the invention, in the fermentation of step (f), the fermentation may be carried out at an incubator temperature of 30 to 45 ℃, specifically at 32 to 40 ℃, and more specifically at 35 to 38 ℃.

[0046] As one embodiment of the invention, in the fermentation of step (f), the fermentation may be carried out in a culture vessel for 24 to 120 hours, specifically for 48 to 96 hours, and more specifically for 72 hours.

[0047] As one embodiment of the invention, a method for preparing a lactic acid bacteria fermentation composition of the guava leaf extract comprises the following steps: (1) purchasing guava leaves, which are the fermentation raw material, from the market or a farm, adding guava leaves and purified water in a ratio of 5-15 : 85-95 weight%, heating until the yield reaches 85%, then cooling at room temperature, and filtering the resulting guava leaf extract to remove impurities mixed in with a cotton cloth, etc. (2) The guava leaf extract filtered in step (1) above may be pasteurized at 60-68°C for 30 minutes, then separately cultured lactic acid bacteria of Leuconostoc mesenteroides (MGE 3138), Lactobacillus plantarum (MGE 3143), and Leuconostoc citrium Cares-1 are inoculated at 1-2% (w / w) relative to the guava leaf extract, and then fermented in an incubator at 35-38°C for 72 hours.

[0048] The present invention also includes a step of evaluating a fermented liquid with enhanced antioxidant efficacy by measuring the sugar content, pH, ABTS radical scavenging ability, DPPH radical scavenging ability, total polyphenol content, and total flavonoid content of the guava leaf lactic acid bacteria fermented liquid.

[0049] In addition, the present invention provides the results of measuring the number of lactic acid bacteria contained in a lactic acid bacteria fermentation liquid having antioxidant efficacy, wherein the fermentation composition obtained by fermenting guava leaf extract with lactic acid bacteria is used.

[0050] As one embodiment of the invention, the guava leaf fermentation composition fermented through the Leuconostoc mesenteroides (MGE 3138) may have a sugar content of 1 to 1.35 brix, specifically 1.1 to 1.3 brix, and more specifically 1.2 to 1.27 brix.

[0051] As one embodiment of the invention, the guava leaf fermentation composition fermented through Lactobacillus plantarum (MGE 3143) may have a sugar content of 1 to 1.35 brix, specifically 1.1 to 1.3 brix, and more specifically 1.2 to 1.23 brix.

[0052] As one embodiment of the invention, the guava leaf fermentation composition fermented through the Leuconostoc citrium Cares-1 may have a sugar content of 1 to 1.35 brix, specifically 1.1 to 1.32 brix, and more specifically 1.2 to 1.3 brix.

[0053] As one embodiment of the invention, the pH of the guava leaf fermentation composition fermented through the Leuconostoc mesenteroides (MGE 3138) may be 4.5 to 5.0, specifically the pH may be 4.7 to 4.85, and more specifically the pH may be 4.75 to 4.82.

[0054] As one embodiment of the invention, the pH of the guava leaf fermentation composition fermented through Lactobacillus plantarum (MGE 3143) may be 4.0 to 5.0, specifically the pH may be 4.3 to 4.8, and more specifically the pH may be 4.5 to 4.79.

[0055] In one embodiment of the invention, the pH of the guava leaf fermentation composition fermented through the Leuconostoc citrium Cares-1 may be 4.5 to 5.0, specifically 4.7 to 4.9, and more specifically 4.71 to 4.85. In one embodiment of the invention, the viable cell count of the guava leaf fermentation composition fermented through the Leuconostoc mesenteroides (MGE 3138) is 3.0 x 10 5 Up to 9 x 10 7 It could be, specifically, the viable cell count is 3.5 x 10 5 Up to 8.5 x 10 7 It may be, and more specifically, the viable cell count is 3.7 x 10 5 Up to 8.2 x 10 7 It is.

[0056] As one embodiment of the invention, the viable cell count of the guava leaf fermentation composition fermented with Lactobacillus plantarum (MGE 3143) is 1.0 x 10 4 Up to 3 x 10 8 It could be, specifically, the viable cell count is 1.2 x 10 4 Up to 2.5 x 10 8 It may be, and more specifically, the viable cell count is 1.3 x 10 4 Up to 2.3 x 10 8 It is.

[0057] As one embodiment of the invention, the viable cell count of the guava leaf fermentation composition fermented through Leuconostoc citrium Cares-1 is 2.5 x 10 5 Up to 7 x 10 7 It could be, specifically, the viable cell count is 3.0 x 10 5 Up to 6.5 x 10 7 It may be, more specifically, the viable cell count is 3.1 x 10 5 Up to 6.0 x 10 7 However, the number of viable cells mentioned above gradually decreases as the fermentation time progresses, resulting in a cell count of 80 or fewer.

[0058]

[0059] As one embodiment of the invention, the present invention may provide a food composition comprising a lactic acid bacteria-fermented guava leaf extract.

[0060] As an embodiment of the invention, the food composition may include food-grade acceptable food additives in addition to the active ingredient. The food additive refers to a component that can be added to food as an auxiliary component, and any food additive known in the industry that is added to the preparation of food of each formulation may be used without limitation. In the present invention, any food additive that assists in the anti-inflammatory effect of the food composition without significantly altering the properties of the food composition may be used without limitation.

[0061] As an embodiment of the invention, the food composition may be, for example, various types of food, beverages, chewing gum, tea, vitamin complexes, health functional foods, etc. Additionally, in the present invention, food includes, but is not limited to, special nutritional foods (e.g., infant formula, baby food, etc.), processed meat products, fish products, tofu products, jelly products, noodles (e.g., ramen, noodles, etc.), health supplements, seasoning foods (e.g., soy sauce, soybean paste, red pepper paste, mixed sauce, etc.), sauces, confectionery products (e.g., snacks), dairy products (e.g., fermented milk, cheese, etc.), other processed foods, kimchi, pickled foods (various types of kimchi, pickled vegetables, etc.), beverages (e.g., fruit and vegetable beverages, soy milk, fermented beverages, etc.), and natural seasonings (e.g., ramen soup mix).

[0062] Examples of food additives include various nutritional supplements, vitamins, minerals (electrolytes), flavoring agents such as synthetic and natural flavoring agents, coloring agents and fillers, pectic acid and its salts, alginic acid and its salts, organic acids, protective colloidal thickeners, pH adjusters, stabilizers, preservatives, glycerin, alcohol, and carbonating agents used in carbonated beverages.

[0063] The above food composition may be used as a health functional food having an antioxidant function. The above health functional food refers to a food manufactured and processed in the form of tablets, capsules, powders, granules, liquids, and pills using raw materials or ingredients that have functional properties useful to the human body. Here, functional properties mean obtaining effects useful for health purposes, such as regulating nutrients or physiological actions on the structure and function of the human body.

[0064] In addition, the above food composition can be used as an additive to various foods. Foods to which this food composition can be added may include meat, sausage, bread, chocolate, candies, snacks, confectionery, pizza, ramen, other noodles, chewing gum, dairy products including ice cream, various soups, beverages, tea, drinks, alcoholic beverages, and vitamin complexes, without any limitation on the type of food.

[0065] As one embodiment of the invention, the present invention may provide a lactic acid bacteria kit for producing guava leaf extract fermented with lactic acid bacteria.

[0066]

[0067] One or more specific examples are described in more detail below through embodiments. However, these embodiments are intended to illustrate one or more specific examples and the scope of the present invention is not limited to these embodiments.

[0068]

[0069] Example 1. Preparation of Guava Leaf Juice

[0070] The guava leaves used as raw materials in the present invention were purchased from the market or farms, and the guava leaves and purified water were added in a ratio of 5-15 : 85-95% by weight. The mixture was heated until the yield reached 85%, and then cooled at room temperature for 6 hours. The resulting guava leaf extract was used as the guava leaf extract by filtering out the guava leaf residue mixed in with cotton cloth, filter paper, etc.

[0071]

[0072] Example 2. Fermentation of guava leaf extract with lactic acid bacteria (MGE 3138) and preparation of fermentation composition

[0073] The guava leaf extract produced in Example 1 above was pasteurized at 60–68°C for 30 minutes, and then 1–2% (w / w) of Leuconostoc mesenteroides (MGE 3138) lactic acid bacteria cultured separately was inoculated relative to the guava leaf extract, and fermented in an incubator at 35–38°C for 72 hours (Fig. 1).

[0074]

[0075] Example 3. Fermentation of guava leaf extract with lactic acid bacteria (MGE 3143) and preparation of fermentation composition

[0076] The guava leaf extract produced in Example 1 above was pasteurized at 60–68°C for 30 minutes, and then Lactobacillus plantarum (MGE 3143) cultured separately was inoculated at 1–2% (w / w) relative to the guava leaf extract, and fermented in an incubator at 35–38°C for 72 hours.

[0077]

[0078] Example 4. Fermentation of guava leaf extract with lactic acid bacteria (Cares-1) and preparation of fermentation composition

[0079] The guava leaf extract produced in Example 1 above was pasteurized at 60–68°C for 30 minutes, and then 1–2% (w / w) of lactic acid bacteria of Leuconostoc citrium Cares-1 cultured separately was inoculated relative to the guava leaf extract, and then fermented in an incubator at 35–38°C for 72 hours.

[0080]

[0081] Experimental Example 1. Measurement of Sugar Content and pH

[0082] The sugar content was measured in 3 replicates using a refractometer at 24-hour intervals for the guava leaf extract being fermented with lactic acid bacteria, and the average value was calculated. Similarly, the pH was measured in 3 replicates using a pH meter at 24-hour intervals for the guava leaf extract being fermented with lactic acid bacteria by adding 9 ml of distilled water to 1 ml of the extract being fermented, and the average value was calculated.

[0083]

[0084] In Experimental Example 1 above, the results of the sugar content measurement of the guava leaf fermentation composition over time are shown in Table 1, and the results of the pH measurement are shown in Table 2.

[0085] Results of Brix measurement of fermented guava leaf composition Brix 0 hr 24 hr 48 hr 72 hr L. mesenteroides(MGE 3138)1.20 1.27 1.20 1.27 L. plantarum(MGE 3143)1.20 1.23 1.20 1.23 L. mesenteroidesCares-11.20 1.20 1.23 1.30

[0086]

[0087] pH measurement results of fermented guava leaf composition pH 0 Hour 24 Hour 48 Hour 72 Hour L. mesenteroides(MGE 3138) 4.8 24.8 14.7 54.75 L. plantarum(MGE 3143) 4.7 94.5 24.5 54.53 L. mesenteroidesCares-14.8 54.8 24.8 04.71

[0088]

[0089] Experimental Example 2. Measurement of viable cell count

[0090] The viable cell count was determined by adding 9 ml of sterile water to 1 ml of the extract being fermented and diluting it using the 10-fold dilution method, then plating 3 samples of each dilution factor onto MRS Agar, incubating in an incubator at 37 ℃ for 48 hours, and counting the colonies.

[0091] In Experimental Example 2 above, the results of measuring the number of viable lactic acid bacteria in the guava leaf fermentation composition over time are shown in Table 3.

[0092] Results of measuring viable lactic acid bacteria count in fermented guava leaf composition Sugar content 0 hours 24 hours 48 hours 72 hours L. mesenteroides (MGE 3138) 3.7X10 5 8.2x10 7 TFTCTFTCL. plantarum(MGE 3143)5.0Х10 5 2.3x10 8 1.3X10 4 TFTCL. mesenteroidesCares-13.1Х10 5 6.0X10 7TFTCTFTC-TNTC indicates that measurement is impossible due to the excessive number of cells. -TFTC indicates that it can be displayed when the number of cells is 30 or less.

[0093]

[0094] Experimental Example 3. ABTS radical scavenging ability

[0095] The ABTS radical cation decolorization of the fermented guava leaf composition was measured by preparing 7.0 mM ABTS (2,2-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid)) and 2.45 mM potassium persulphate, leaving the solution in the dark for 16 hours to form cations (ABTS+), and then diluting the solution to obtain an OD value of 0.7–0.9 by measuring the absorbance at 734 nm. 0.4 mL of the sample was added to 11.6 mL of the diluted ABTS+ solution, and after exactly 10 minutes, the solution was centrifuged at 12,000 rpm for 10 minutes, after which the absorbance at 734 nm was measured. A standard curve was constructed using 1 mM ascorbic acid as a standard, and the antioxidant capacity (AEAC, ascorbic acid equivalent antioxidant capacity, mg%) of the sample was calculated.

[0096]

[0097] In Experimental Example 3 above, the results regarding the ABTS radical scavenging ability of the guava leaf fermentation composition over time are shown in Table 4 (Fig. 2).

[0098]

[0099] Results of ABTS radical scavenging activity measurement of fermented guava leaf composition ABTS0 Hour 24 Hour 48 Hour 72 Hour L. mesenteroides(MGE 3138)35.15 6.54 6.04 4.1 L. plantarum(MGE 3143)34.15 4.34 6.34 4.6 L. mesenteroidesCares-135.05 5.44 6.54 5.0

[0100]

[0101] Experimental Example 4. DPPH radical scavenging activity

[0102] Radical scavenging activity against DPPH (1,1-diphenyl-2-picrylhydrtazyl) was measured using the reducing power of DPPH. Specifically, 9 mL of 0.2 mM DPPH solution (dissolved in 99.9% ethyl alcohol) was added to 1 mL of the sample and mixed for 10 seconds. The mixture was then reacted in the dark at room temperature for 10 minutes, and the absorbance was measured at a wavelength of 517 nm using a spectrophotometer (Optizen 1412V, Mecasys Co., Korea). Ascorbic acid was used as a positive control; the solution was diluted to different concentrations, a standard curve was constructed, and the results were expressed as Ascorbic acid Equivalent Antioxidant Capacity (mg AEAC / g).

[0103]

[0104] In Experimental Example 4 above, the results regarding the DPPH radical scavenging ability of the guava leaf fermentation composition over time are shown in Table 5 (Fig. 3).

[0105]

[0106] Results of DPPH radical scavenging activity measurement of fermented guava leaf composition DPPH 0 Hour 24 Hour 48 Hour 72 Hour L. mesenteroides(MGE 3138)85.377.075.876.0L. plantarum(MGE 3143)86.378.777.778.0L. mesenteroidesCares-182.176.674.775.2

[0107]

[0108] Experimental Example 5. Total polyphenol content (TPC)

[0109] Polyphenol content was analyzed by absorbance using a modified method of Lee et al., based on the principle that Folin-Ciocalteu's phenol reagent develops molybdenum blue as a result of reduction by polyphenolic compounds in the extract. 2 mL of the sample was diluted with 8 mL of distilled water, 1 mL of 2N Folin-Ciocalteu reagent (Sigma-Aldrich, USA) was added and left for 5 minutes, after which 10 mL of 7% Na2CO₃ was added. Absorbance was measured at 750 nm after 2 hours at room temperature. Gallic acid was used as a standard by serial dilution, and the total polyphenol content was calculated by constructing a calibration curve (y=0.0154x-0.7823; R²=0.9978).

[0110]

[0111] In Experimental Example 5 above, the results regarding the polyphenol content of the guava leaf fermentation composition over time are shown in Table 6 (Fig. 4).

[0112]

[0113] Results of measuring the total polyphenol content of fermented guava leaf composition TPC0 Hour 24 Hour 48 Hour 72 Hour L. mesenteroides(MGE 3138)286.9294.6308.3283.5 L. plantarum(MGE 3143)281.2294.6311.1279.5 L. mesenteroidesCares-1289.4303.4308.4282.8

[0114]

[0115] Experimental Example 6. Total flavonoid content (TFC)

[0116] Total flavonoid content was measured by modifying the method of Shin et al. 5 mL of the sample was mixed with 0.75 mL of 5% NaNO2 and left at room temperature for 6 minutes, then 1.5 mL of 10% AlCl3 was added and left for 5 minutes. After dilution by adding 5 mL of 1N NaOH solution, the absorbance was measured at 510 nm. Quercetin was used as the standard by serial dilution, and the total flavonoid content was calculated by constructing a calibration curve (y=0.3145x+0.0026; R²=0.9998).

[0117]

[0118] In Experimental Example 6 above, the results regarding the flavonoid content of the guava leaf fermentation composition over time are shown in Table 7 (Fig. 5).

[0119]

[0120] Results of measuring total flavonoid content of fermented guava leaf composition TFC0 Hour 24 Hour 48 Hour 72 Hour L. mesenteroides(MGE 3138)1337.61015.51127.51366.4 L. plantarum(MGE 3143)1334.81389.51138.01359.0 L. mesenteroidesCares-11319.31430.31128.01359.0

[0121]

[0122] The present invention has been described above with reference to its preferred embodiments. Those skilled in the art will understand that the present invention may be embodied in modified forms without departing from the essential characteristics of the invention. Therefore, the disclosed embodiments should be considered in an illustrative rather than a restrictive sense. The scope of the invention is defined by the claims, not by the foregoing description, and all variations within the scope of the claims should be interpreted as being included in the invention.

[0123]

[0124] This invention is highly useful from the perspective of the food industry because it enhances the antioxidant efficacy of guava leaves—a natural product with excellent antioxidant properties—through lactic acid fermentation, thereby incorporating the taste and aroma of guava leaves into food while simultaneously supplying nutrients beneficial to the human body, which can be expanded into the food processing and functional food markets.

Claims

1. A method for preparing a fermented guava leaf composition comprising the following steps: (a) a step of obtaining a guava leaf extract by adding guava leaves to purified water and heating; (b) a step of cooling the guava leaf extract produced in step (a) above; (c) A step of filtering the guava leaf extract cooled in step (b) above; (d) A step of pasteurizing the guava leaf extract filtered in step (c) above; (e) a step of inoculating lactic acid bacteria into the guava leaf extract sterilized in step (d) above; and, (f) A step of fermenting the guava leaf extract inoculated with lactic acid bacteria in step (e) above in a culture medium.

2. In Paragraph 1, A method in which, in step (e) above, the lactic acid bacteria is one or more strains selected from the group consisting of strains of the genus Leuconostoc sp., Bifidobacterium sp., Streptococcus sp., Leuconostoc sp., Enterococcus sp., Peptostreptococcus sp., and Lactobacillus sp.

3. In Paragraph 1, A method in which, in step (e) above, the lactic acid bacteria are inoculated in an amount of 0.1 to 3 weight % relative to the guava leaf extract.

4. A fermented guava leaf composition produced by the method of Paragraph 1.

5. A food composition comprising the guava leaf fermentation composition of Paragraph 4.

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