Fermented lactobacillus mucilaginosus FUA033 fermented cranberry juice product and preparation method thereof

Abstract

The invention belongs to the field of microbial fermentation, and particularly relates to a fermented cranberry juice product prepared from fermented lactobacillus mucilaginosus FUA033 and a preparation method of the fermented cranberry juice product. The cranberry juice is fermented by using the fermentation lactobacillus mucus FUA033 capable of converting ellagic acid to generate urolithin A, the ellagic acid in the cranberry juice is converted into urolithin A with multiple biological activities of relieving muscle decline, resisting inflammation, resisting tumors and the like, the antioxidant activity of the cranberry juice is improved, the nutritional ingredients of the cranberry juice are enriched, and the cranberry juice is rich in nutrition and rich in nutrition. The cranberry juice prepared by the preparation method disclosed by the invention not only contains a plurality of antioxidant components, but also contains urolithin A with rich biological activity, can also provide probiotics such as lactobacillus mucus FUA033 and the like for a human body, and has a good application prospect.

Description

Technical Field

[0001] The invention belongs to the field of microbial fermentation, and particularly relates to a cranberry juice product fermented by fermenting Lactobacillus mucilaginosus FUA033 and a preparation method thereof. Background Art

[0002] Fermented foods and drinks have been an important part of the human diet since ancient times, and their positive effects on health have been widely recognized. Studies have shown that fermented foods can significantly reduce the risk of diseases such as high blood pressure, diabetes, obesity, high cholesterol, diarrhea and thrombosis. These benefits are closely related to the bioactive substances generated during the fermentation process. Fermented fruit and vegetable juices are highly valued because they are rich in health-promoting antioxidants such as vitamin C and various polyphenol compounds.

[0003] Cranberries are not only delicious, but also contain a variety of ingredients that are beneficial to the human body, such as flavonoids, ellagic acid, anthocyanins, and polyphenols and organic acids derived from flavan-3-ols. Ellagic acid is a polyphenolic substance rich in berries and nuts. Due to its low solubility, it has low absorption and utilization by the human body. However, after being metabolized by intestinal microorganisms, urolithin substances are generated. Among them, urolithin A is currently the only compound clinically shown to improve muscle function through mitochondrial autophagy. It also has biological activities such as anti-cancer, anti-inflammatory, improving immunity, and improving cognitive impairment, and it is risk-free to human health. However, more than 40% of the intestinal flora of people over 31 years old cannot convert ellagic acid to urolithin A. In 2021, Amazentis will develop chemically synthesized urolithin A as a nutritional supplement to delay muscle decline in the elderly. However, chemically synthesized urolithin A pollutes the environment and is expensive. Therefore, it is urgent to develop fermented foods rich in urolithin A and probiotics so that the elderly can resist muscle decline while enjoying delicious food.

[0004] Cranberry, with good color, aroma and taste, rich nutrition, is known as the "king of fruits", and has a high content of ellagic acid. The present invention utilizes strains to ferment cranberries to convert ellagic acid into urolithin A, thereby improving the nutritional efficacy and value of cranberries, opening up a new track for healthy drinks, promoting the added value of agricultural product processing, and helping the development of the agricultural and rural economy; providing source support for the research and development of major core technologies for fruit and vegetable processing. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention provides a cranberry juice product fermented by fermented Lactobacillus mucilaginosus FUA033 and a preparation method thereof.

[0006] The technical scheme of the present invention is as follows: A method for preparing a cranberry juice product fermented by fermenting Lactobacillus mucilaginosus FUA033

[0007] 1) Activation of strains: The fermented Lactobacillus mucilaginosus FUA033 stored in a -80°C refrigerator was activated by streaking on a plate;

[0008] 2) Seed culture: Pick a single activated colony and inoculate it into MRS liquid culture medium, and culture it in static anaerobic culture to obtain seed liquid;

[0009] 3) Preparation of fermented cranberry juice sample: fresh cranberries are squeezed with a juicer, centrifuged, and the supernatant is placed in an anaerobic culture bottle; sterilized; processed cranberry juice is obtained; the seed liquid obtained in step 2) is inoculated into the processed cranberry juice at 2% (v / v), and anaerobically cultured.

[0010] Preferably, in step 2), the components of the MRS liquid culture medium include: 1% tryptone, 1% beef extract, 0.5% yeast extract and 2% glucose.

[0011] Preferably, in step 3), the method for treating cranberry juice is: centrifuging at 4000×g for 5 min, taking the supernatant into an anaerobic culture bottle, pasteurizing at 85° C. for 15 min, and cooling to room temperature.

[0012] Preferably, in step 3), the pH of the fermented cranberry-like liquid is 3.38.

[0013] Preferably, in step 3), the anaerobic culture is carried out at 37° C. for 48 hours.

[0014] The cranberry juice product prepared by the method of the present invention has a urolithin A content of 8 μM.

[0015] The cranberry juice product prepared by the method of the present invention has a DPPH free radical scavenging ability of 160.1 μg Trolox / mL.

[0016] Beneficial effects of the present invention: The cranberry products obtained by the method of the present invention have rich fruity aroma, bright color and full fragrance; the cranberry products obtained by this method have better antioxidant effects than ordinary cranberry products, and they also have unique anti-aging effects due to their ability to convert ellagic acid into urolithin A. In terms of antioxidant activity, the Trolox equivalent antioxidant capacity (TEAC) of DPPH and ABTS+ of cranberry juice fermented by strain FUA033 were 160.1μg Trolox / mL and 110μm / mL, respectively, which is more than 2.5 times the antioxidant effect of Zhang Jinlan et al. using Lactobacillus rhamnosus LGG to ferment wolfberry juice. Similarly, the superoxide anion free radical scavenging rate measured after strain FUA033 fermented cranberry juice was better than 58% of the effect of Xia Qiuxia et al. using Lactobacillus acidophilus CICC20250 to ferment Solanum nigrum fruit. In addition, in terms of the yield of urolithin A converted from ellagic acid, compared with the urolithin A content of 8.99 μmol / L when Liu Qitong et al. fermented pomegranate peel with thermophilic Streptococcus FUA329, the urolithin A content in cranberry juice fermented by strain FUA033 was significantly increased, reaching 25.08 μmol / L. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 pH measurement and colony count of cranberry sample before and after fermentation

[0018] Figure 2 Determination of total phenolic and flavonoid contents in cranberry juice samples before and after fermentation

[0019] Figure 3 Determination of antioxidant activity of fermented cranberry juice

[0020] Figure 4 Comparison of liquid chromatography and mass spectrometry of cranberry juice before and after fermentation

[0021] Figure 5 Caenorhabditis elegans survival and phenotypic assays

[0022] Figure 6 Caenorhabditis elegans stress resistance experiment

[0023] Figure 7 Measurement of mitochondrial function and content in Caenorhabditis elegans

[0024] Figure 8 Antioxidant capacity assay in Caenorhabditis elegans DETAILED DESCRIPTION

[0025] The following embodiments can enable those skilled in the art to more fully understand the present invention, but the present invention is not limited to the scope of the embodiments.

[0026] Example 1 Activation of fermented Lactobacillus mucilaginosus FUA033

[0027] Activation steps:

[0028] (1) The original strain of Lactobacillus mucosa FUA033 stored in an ultra-low temperature refrigerator at -80°C was separated and purified, and then inoculated into MRS liquid culture medium and cultured at 37°C for 18 hours with an inoculum size of 1% (v / v) to reach an appropriate growth stage. After the culture, the strains were mixed with 25% volume ratio of sterile glycerol to form a strain glycerol suspension, and immediately stored in an ultra-low temperature refrigerator at -80°C for preservation. This step ensures the activity and stability of the strains during long-term storage, facilitating future research and application. The components of MRS liquid culture medium include: 1% tryptone, 1% beef extract, 0.5% yeast extract and 2% glucose.

[0029] Example 2 Preparation of fermented cranberry juice sample

[0030] step:

[0031] Preparation of cranberry fermentation sample: fresh cranberries were extracted with a juicer. Centrifuged at 4000×g for 5 min, the supernatant was placed in an anaerobic culture bottle, pasteurized at 85°C for 15 min, and cooled to room temperature. The activated bacterial solution obtained in Example 1 was inoculated into the treated cranberry juice at 2% (v / v), and anaerobically cultured at 37°C for 48 hours.

[0032] Results: Clarified cranberry juice was obtained. This experiment was a pretreatment step for the determination of physicochemical properties.

[0033] Example 3 pH determination and colony count of fermented cranberry sample solution

[0034] step:

[0035] The pH value of the cranberry juice before and after fermentation in Example 2 was measured by a pH meter. The bacterial solution was diluted with 0.9% sodium chloride solution in a gradient manner, and the total number of colonies was counted by the agar plate method, with each group repeated three times (the specific counting scheme refers to Experiment 1).

[0036] Results: The pH value of cranberry juice increased from 3.26 to 3.38 after fermentation (p<0.01), which may be due to the fact that Lactobacillus mucilaginosus FUA033 converted some of the more acidic organic acids into weak acids during the fermentation process. At the same time, the total number of colonies reached 10 after 48 hours of fermentation. 8 The CFU / mL level indicates that the number of strains has reached the level that can play a beneficial role in the human body.

[0037] Example 4 Determination of total phenolic and flavonoid contents in fermented cranberry juice samples

[0038] Steps: The flavonoid and total phenol content determination experiment was completed using the corresponding kits produced by Beijing Solebow Technology Co., Ltd. The experimental sample solution was the fermentation sample solution prepared in Experiment 2 (0h, 48h)

[0039] Experimental results: After cranberry juice was fermented with Lactobacillus mucilaginosus FUA033, the total phenol content increased significantly from 0.76 mg / mL to 1.81 mg / mL (p<0.05), and the total flavonoid content increased from 0.16 mg / mL to 0.21 mg / mL.

[0040] Example 5 Determination of antioxidant activity of fermented cranberry juice

[0041] step:

[0042] (1) Determination of total antioxidant capacity by ABTS method: The fermentation sample solution (0H, 48H) prepared in Experiment 2 was mixed with 0.9% sodium chloride solution in a ratio of 1:9 (v / w) to prepare the test sample solution; 0.2 mL of the test sample solution was added to 1.8 mL of the pre-prepared ABTS working solution and mixed evenly; the mixture was reacted for 6 minutes in a dark environment to allow for sufficient reaction; the absorbance of the mixture was measured at a wavelength of 405 nm using an ELISA reader to evaluate the antioxidant capacity of the sample.

[0043] (2) 0.1 mL of the fermentation sample solution (0H, 48H) prepared in Experiment 2 was mixed with 3.9 mL of 0.025 g / L DPPH solution; the mixture was reacted at room temperature in the dark for 30 minutes to achieve full reaction; the absorbance of the mixture was measured using a spectrophotometer at a wavelength of 515 nm; as a blank control, 0.1 mL of anhydrous ethanol and 3.9 mL of DPPH solution were treated in the same manner as above; a standard curve was prepared: the standard powder was added to 2 mL of 80% methanol to fully dissolve, i.e., 0.5 mg / mL (Trolox) standard application solution, and then diluted with 80% methanol to 5 μg / mL, 10 μg / mL, 15 μg / mL, 20 μg / mL, and 25 μg / mL, respectively, and mixed, and allowed to stand at room temperature at 25°C in the dark for 30 min, with a wavelength of 517 nm and a 1 cm optical microscope, to measure the absorbance of each tube.

[0044] (3) The Fenton reaction is the most common chemical reaction that produces hydroxyl radicals. The amount of H2O2 and the OH produced by the Fenton reaction are proportional to each other. - The amount of OH- is proportional to the amount of OH-. When the electron acceptor is given, the red substance is developed with the Griess reagent, and its color is proportional to the amount of OH-. This experiment was completed using the hydroxyl radical (OH-) determination kit (Cat. No.: A018-1-1) produced by Nanjing Jiancheng Bioengineering Research Institute. The experimental sample solution is the fermentation sample solution (0H, 48H) prepared in Experiment 2.

[0045] Results: The DPPH free radical scavenging ability was significantly increased from 75.75 μg Trolox / mL to 160.1 μg Trolox / mL (p<0.001), and the total antioxidant capacity and hydroxyl radical scavenging rate determined by ABTS were significantly improved (p<0.01). Combined with the conclusion of Example 4, this may be due to the fact that the bioavailability of polyphenols has been significantly improved under the action of microbial glucosidase, thereby enhancing the ability of in situ free radical scavenging and activating the natural antioxidant defense system. Through the hydrolysis of the polymer (such as the decomposition of esterified phenolic compounds), the content of vitamins, minerals and phenolic compounds is increased, thereby improving the antioxidant capacity of the product.

[0046] Example 6 Quantitative Analysis of Urolithin A

[0047] step:

[0048] Urolithin A was analyzed on a Q-Exactive LC-MS / MS (Thermo Fisher) using a C18 column (Waters Ltd., Massachusetts, USA). BEH C18, 2.1×50mm, 1.7μm, flow rate 0.5mL / min. Chromatographically pure C2H3N (A) was used as the organic phase, and H2O:HCOOH (99:1, V:V) (B) was used as the aqueous phase. Chromatographic separation of culture samples was performed at a flow rate of 1mL / min. The gradient started at 20% A and 80% B; at 15 minutes, A increased to 70% and B decreased to 30%; at 20 minutes, A increased to 95% and B decreased to 5%; at 21 minutes, A reached 100% and B was 0%; at 23 minutes, A and B remained at 100% and 0%; from 24 to 25 minutes, A returned to 20% and B returned to 80%, followed by 25 to 30 minutes of post-chromatographic run time. UV chromatograms were recorded at 255 and 305nm.

[0049] Results: Urolithin A was detected at about 8.9 minutes in the fermented cranberry juice by high performance liquid chromatography (HPLC), while the baseline before fermentation tended to zero. In addition, by mass spectrometry, urolithin A was not detected in the cranberry juice before fermentation, but was detected at about 4.69 minutes after fermentation. These results indicate that Lactobacillus mucilaginosus FUA033 converted ellagic acid in cranberry juice into urolithin A during the fermentation process, and its content reached 8 μM.

[0050] The results fully demonstrate the metabolic activity of Lactobacillus mucilaginosus FUA033 during the fermentation process, which can effectively convert ellagic acid into biologically active urolithin A. This conversion process not only increases the functional component content of cranberry juice, but also improves its potential health benefits. These findings are of great significance for understanding the application potential of Lactobacillus mucilaginosus FUA033 in fermented foods, especially in improving the antioxidant capacity of foods and increasing the content of beneficial health components.

[0051] Example 7 Fermented cranberry juice intervention in Caenorhabditis elegans experiment

[0052] Procedure: C. elegans was cultured on nematode growth medium (NGM) agar plates, and E. coli OP50 was used to feed C. elegans at a temperature of 20°C. Nematodes were synchronized using the hypochlorite method: pregnant nematodes were collected in a 2 mL centrifuge tube, washed 3 times with M9 solution, and then enriched in 1 mL M9 solution. The nematodes were treated with 2 mL of a solution containing 1 M NaOH and 10% NaClO (1:1) and vortexed for 5-8 minutes until the solution in the tube was clear. At this time, all nematodes were lysed, centrifuged at 3000 × g for 3 minutes, and the supernatant was discarded. The collected nematode eggs were washed 3-4 times with M9 solution. An appropriate amount of nematode eggs were inoculated on a nematode growth medium (NGM) agar plate containing E. coli and incubated at 20°C for 4 days until adulthood (L4 stage).

[0053] 100 mL of unfermented or fermented cranberry juice was extracted using equal amounts of ether and ethyl acetate and these samples were concentrated under freeze vacuum until dryness. Unfermented cranberry juice (NFCJ) and fermented cranberry juice (FCJ) extracts were dissolved in 1 mL of DMSO, then diluted with 99 mL of E.coli OP50 bacterial culture and finally plated on NGM plates. C. elegans were exposed to these extracts throughout their life, from the L4 stage until death. Synchronized L4 adults were maintained at 20°C and plated on NGM agar plates of E.coli OP50. Different amounts of urolithin A (UA) fermented or unfermented cranberry juice were dissolved in a mixed solvent of sterile ddH2O and DMSO (V / V: ddH2O:DMSO=3:1) and added to the nematode growth medium. There were blank control group (nematodes fed with E. coli OP50 solution), positive control group (nematodes fed with E. coli OP50 solution containing different concentrations of urolithin A), and experimental group (fermented or unfermented cranberry juice). The nematodes in the plates of each group were transferred to new plates every two days until they reached the measurement day.

[0054] Example 8 Survival and phenotype determination of Caenorhabditis elegans

[0055] step:

[0056] (1) After synchronization, the nematodes were raised to the L4 stage and transferred to 25°C. After 24 h at this temperature, 100 nematodes from the NGM plates with different feeding conditions were placed into three replicate plates. After 7 days, the nematodes were transferred to fresh plates and survival scores were performed every 2 days. Lifespan was measured at 20°C.

[0057] (2) The daily egg-laying capacity of C. elegans was measured on the 1st to 5th day after the intervention of cranberry juice fermented by strain FUA033. There was only one L4 C. elegans on each plate. The number of eggs laid by the nematodes was counted every 24 h, and the nematodes were transferred to a new culture dish until the nematodes stopped laying eggs. The total number of eggs laid each day was counted and a curve was drawn.

[0058] Results: Movement ability is closely related to life span, and the body curvature of C. elegans decreases with age. From the results of the life span experiment, the life span curves of the positive group and the experimental group shifted to the right. At the same time, the body curvature of the nematodes was measured at four time points during the growth of the nematodes to study whether the fermented cranberry juice of strain FUA033 can improve the movement ability of nematodes. Compared with the control group, the intervention of the positive group and the experimental group can effectively inhibit the age-related decline in the movement ability of nematodes. In addition, the extension of the life span of C. elegans is usually associated with a decrease in fertility. The positive group and the experimental group can increase the number of eggs laid by nematodes, among which the fermented cranberry juice treatment has the highest egg-laying ability.

[0059] Example 9 Caenorhabditis elegans stress resistance experiment

[0060] step:

[0061] (1) After being treated with fermented or unfermented cranberry juice at 20°C for 8 days, C. elegans were incubated at 35°C and the number of deaths was recorded every 2 hours until all control C. elegans died.

[0062] (2) Thirty synchronized nematodes at the L4 stage were randomly selected and divided into four groups. They were inoculated into NGM medium containing cranberry juice fermented by Lactobacillus mucilaginosus FUA033 and unfermented cranberry juice, respectively. After 8 days of intervention, the nematodes were acutely exposed to 0.1% H2O2 in a 48-well plate, with 10 nematodes in each well and three replicates per group. The number of surviving nematodes was counted every 30 minutes and the survival curve was drawn until all nematodes died.

[0063] Results: To understand whether FCJ can exert anti-aging effects by enhancing the resistance of C. elegans to heat stress and oxidative stress, we conducted heat stress and oxidative stress tests in nematodes. Compared with the control group, FCJ intervention increased the survival rate of nematodes exposed to 37°C heat stress, and HO -Under the induced acute oxidative stress, FCJ still showed a higher survival rate than other control groups. In summary, FCJ treatment can effectively improve the resistance of nematodes to heat stress and oxidative stress.

[0064] Example 10 Measurement of Mitochondrial Function and Content in Caenorhabditis elegans

[0065] step:

[0066] (1) Mitochondrial membrane potential (MMP) was measured using the Mitochondrial Membrane Potential Assay Kit (M8650, Solarbio, Beijing, China) according to the manufacturer's instructions. All C. elegans individuals were collected from the plate, washed with M9 buffer solution, incubated with 2 μM JC-1 dye for 20 min, washed three times with buffer solution, and imaged using an inverted fluorescence microscope (excitation / emission of red fluorescence: 585 / 590 nm; excitation / emission of green fluorescence: 515 / 529 nm). The ratio of red fluorescence intensity (polarized) to green fluorescence intensity (depolarized) was calculated using ImageJ software as a measure of relative MMP.

[0067] (2) According to the manufacturer's instructions, adenosine triphosphate (ATP) content was measured using an ATP content kit (BC0300, Solarbio, Beijing, China). 100 Caenorhabditis elegans individuals were collected and washed with M9 buffer, and mitochondrial specific fluorescent staining was performed using MitoTrackerGreen, and then washed three times with M9 buffer; finally, the ATP level was measured using a microplate reader (excitation / emission: 490 / 516 nm).

[0068] Results: Mitochondria are the main sites for aerobic respiration and energy production, and the level of reactive oxygen species (ROS) produced by their activities is closely related to aging in nematodes. Appropriate inhibition of the activity of the mitochondrial respiratory chain may have the effect of prolonging life. Normal MMP is a prerequisite for maintaining mitochondrial oxidative phosphorylation and ATP production; in addition, MMP stability is conducive to maintaining the normal physiological function of cells. The reduction of MMP is a landmark event in the early stage of apoptosis. Therefore, this experiment used the fluorescent dye JC-1 to evaluate Caenorhabditis elegans, and further detected the MMP and ATP levels of aged Caenorhabditis elegans after 8 days of FCJ intervention (day 8). The results showed that the MMP in the FCJ group was about 30% higher than that in the control group, and the ATP level was significantly lower than that in the control group. We speculate that after FCJ intervention, dysfunctional mitochondria undergo autophagy, the mitochondrial content decreases, and thus the amount of ROS produced decreases. These results indicate that FCJ promotes autophagy of dysfunctional mitochondria.

[0069] Example 11 Determination of antioxidant capacity of Caenorhabditis elegans

[0070] step:

[0071] Transfer 200 ± 5 nematodes per group into a 1.5 ml sterile Eppendorf tube containing 1 ml PBS. Sonicate the nematodes using an ultrasonic cell disruptor (Vosin, Wuxi, China, BL92-IIDL). 24 . After centrifugation at 4000r / min for 15min, the supernatant was carefully transferred to a new sterile Eppendorf tube and incubated in a water bath at 60°C for 15min, followed by a second centrifugation at 4000r / s for 20min. The resulting supernatant was used for enzyme assays. C. elegans was collected from the plate and washed with saline. Then, C. elegans was homogenized on ice using ultrasound (Ningbo Science Biotechnology, JY92-IIDN) and centrifuged at 12000r / s for 15min. The supernatant was collected and placed on ice for further testing. Next, superoxide dismutase (SOD) activity, catalase (CAT) activity, and glutathione / glutathione disulfide (GSH / GSSG) ratio were determined using SOD (BC0175, Solarbio, Beijing, China), CAT (BC0205, Solarbio, Beijing, China), and GSH / GSSG (A061-1, Nanjing Jiancheng Bioengineering Institute, Nanjing, China) assay kits, respectively, according to the manufacturer’s instructions.

[0072] Results: Compared with the control group, the SOD activity of the experimental group was relatively high, among which the highest 40μm UroA group was 110% higher than the control group, and the CAT activity was also 66%. However, the GSH-Px activity of the experimental group was relatively small, with the maximum increase of about 33%. The sulfhydryl group in GSH can effectively inhibit the damage caused by oxidative stress, and can also serve as a reaction substrate of GSH-Px, effectively remove H2O2, and reduce the level of ROS. The above experimental results show that UA has the effect of enhancing the endogenous antioxidant defense system of nematodes and reducing the level of reactive oxygen in the body, thereby improving its ability to resist oxidative stress.

Claims

1. A method for preparing a cranberry juice product fermented by fermenting Lactobacillus mucilaginosus FUA033: 1) Activation of strains: The fermented Lactobacillus mucilaginosus FUA033 stored in a -80°C refrigerator was activated by streaking on a plate; 2) Seed culture: Pick a single activated colony and inoculate it into MRS liquid culture medium, and culture it in static anaerobic culture to obtain seed liquid; 3) Preparation of fermented cranberry juice sample: fresh cranberries were squeezed with a juicer, centrifuged, and the supernatant was placed in an anaerobic culture bottle; Sterilization; The treated cranberry juice is obtained; the seed solution obtained in step 2) is inoculated into the treated cranberry juice at 2% (v / v) and cultured anaerobically.

2. The preparation method according to claim 1, characterized in that: In the step 2), the components of the MRS liquid culture medium include: 1% tryptone, 1% beef extract, 0.5% yeast extract and 2% glucose.

3. The preparation method according to claim 1, characterized in that: In step 3), the method for treating cranberry juice is: centrifuging at 4000×g for 5 minutes, taking the supernatant into an anaerobic culture bottle, pasteurizing at 85° C. for 15 minutes, and cooling to room temperature.

4. The preparation method according to claim 1, characterized in that: In the step 3), the pH of the fermented cranberry-like liquid is 3.

38.

5. The preparation method according to claim 1, characterized in that: In the step 3), the anaerobic culture is carried out at 37° C. for 48 hours.

6. The cranberry juice product prepared by the preparation method of claim 1, wherein the content of urolithin A is 8 μM.

7. The cranberry juice product prepared by the preparation method of claim 1 has a DPPH free radical scavenging capacity of 160.1 μg Trolox / mL.

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