Fresh corn fermented beverage and preparation method thereof

Abstract

The invention relates to the technical field of microbial fermentation and food production, and particularly provides a fresh corn fermented beverage and a preparation method thereof. The fresh corn fermented beverage is uniform, free of layering and sour and sweet in taste, has corn fragrance, has the pH value of 3.2-4.5, has the living bacteria quantity exceeding 10 < 11 > CFU / mL after leaving a factory, can still maintain the level of 10 < 10 > CFU / mL after being stored for 6 months at normal temperature, and is high in storage stability. The fresh corn fermented beverage does not contain starch, is rich in organic acid and polysaccharide, is high in oxidation resistance, has the effects of conditioning intestinal health, enhancing organism immunity and the like, and is wide in market prospect.

Description

Technical Field

[0001] The invention relates to the technical field of microbial fermentation and food production, and in particular to a fresh corn fermented beverage and a preparation method thereof. Background Art

[0002] Fresh corn refers to young corn with special flavor and quality. Compared with ordinary corn, fresh corn has full grains, bright and natural luster, and produces a lot of sugar, starch, crude fat, and a variety of vitamins and amino acids during the milky stage. It has comprehensive advantages and fashionable characteristics such as high nutritional value, good taste, high added value, good benefits, low fat and high fiber.

[0003] In fresh corn, palatability is the most critical indicator to measure the quality of the variety. Palatability is also called taste. As the name suggests, it refers to the feeling when eating in the mouth. Regarding the palatability of fresh corn, my country defines it as cooking quality and formulates corresponding indicators, which mainly include: sweetness, stickiness, tenderness, smell, flavor, color and thickness of the skin. Among these indicators, sweetness and stickiness are undoubtedly one of the important indicators, but due to simple genetics, abundant resources, and relatively easy breeding of traits. The pericarp is a trait controlled by multiple genes and has a complex genetic relationship, so it is most difficult to improve the palatability of the pericarp. Therefore, in a certain sense, the core of the quality improvement of fresh corn is the improvement of the pericarp. The palatability of the pericarp is the feeling of the skin residue when chewing. Varieties with good pericarp palatability give people a feeling of softness, crispness, no skin residue, and no fiber when chewing.

[0004] At present, the main forms of fresh corn products on the Chinese market are fresh cobs and quick-frozen processing. With the trend of urbanization, consumption patterns have been upgraded. In recent years, the market share of fresh corn deep-processing products such as corn flakes and corn drinks has increased year by year. Among them, corn drinks are suitable for consumers of all ages due to their refreshing taste and healthy properties, especially among young people. Due to their fashionable and healthy characteristics, they are gradually becoming a new favorite in daily life. The market is growing rapidly and the demand is large.

[0005] Strengthening the research and development of corn beverages, improving their nutritional value, and enriching product flavor can not only improve the market structure of corn, but also have important significance in improving the safety level of the corn industry and optimizing the industrial structure of the national economy. Summary of the invention

[0006] The purpose of the present invention is to provide a fresh corn fermented beverage and a preparation method thereof. The fresh corn fermented beverage has a sweet and sour taste, has the aroma of fresh corn, is rich in organic acids and polysaccharides, has a high content of live bacteria, can effectively regulate intestinal health, enhance body immunity, and has broad market prospects.

[0007] In one aspect, the present invention provides a fresh corn fermented beverage, comprising Lactobacillus casei and Bacillus coagulans.

[0008] The Lactobacillus casei is Lactobacillus casei KDB-LC, which has been deposited in the China Center for Type Culture Collection of Wuhan University, Wuhan, China on August 29, 2016, with a deposit number of CCTCCNO: M2016431.

[0009] The Bacillus coagulans is Bacillus coagulans KDB-18, which was deposited in the China Type Culture Collection of Wuhan University, Wuhan, China on July 1, 2024, and its deposit number is CCTCCNO: M20241408.

[0010] The present invention also provides a method for preparing a fresh corn fermented beverage, comprising the following steps:

[0011] (1) preparing fresh corn steep liquor;

[0012] (2) preparing a fermentation medium containing fresh corn steep liquor, sterilizing it, and cooling it;

[0013] (3) inoculating Lactobacillus casei seed liquid into a fermentation medium, culturing in a closed manner at 30-35° C. for 18-24 hours, then inoculating Bacillus coagulans seed liquid, and fermenting aerobically at 36-38° C. for 24-36 hours; after the fermentation is completed, cooling the fermentation liquid to below 10° C.;

[0014] (4) Add prebiotics to the fermentation liquid, perform aseptic filling and packaging, and obtain a fresh corn fermented beverage.

[0015] Further preferably, the fermentation medium in step (2) contains fresh corn steep liquor, skim milk powder, K 2 HPO 4 , KH 2 PO 4 MgSO 4 .

[0016] Further preferably, the components and their mass volume ratios in the fermentation medium in step (2) are: fresh corn steep liquor 80-95 g / L, skim milk powder 100-120 g / L, K 2 HPO 4 25-30g / L, KH 2 PO 4 15-25g / L, MgSO 4 20-30g / L.

[0017] Further preferably, the prebiotic in step (4) is fructooligosaccharide.

[0018] Further preferably, the method for preparing the fresh corn fermented beverage comprises the following steps:

[0019] (1) fresh corn is cleaned and threshed, and corn cobs are discarded to obtain fresh corn kernels; fresh corn kernels and purified water are added into a colloid mill in a mass ratio of 1:2-5, crushed and homogenized, and filtered to obtain fresh corn pulp;

[0020] (2) Add appropriate amount of water to the fermentation tank, add fresh corn syrup, skim milk powder, K 2 HPO 4 , KH 2 PO 4 MgSO 4 After stirring and dissolving, the volume was fixed to obtain a fermentation medium, wherein the contents of the components were 80-95 g / L fresh corn steep liquor, 100-120 g / L skim milk powder, and K 2 HPO 4 25-30g / L, KH 2 PO 4 15-25g / L, MgSO 4 20-30g / L; the initial pH value of the culture medium is 5.5-6.5; high-temperature steam is used to control the pressure in the fermentation tank to 0.09-0.10MPa, the temperature is controlled at 115℃-121℃, sterilize for 25-45min, and then cool down to 37℃;

[0021] (3) inoculating Lactobacillus casei seed liquid into a fermentation medium at a volume ratio of 5-10%, and culturing in a closed manner at 30-35° C. for 18-24 hours; then inoculating Bacillus coagulans seed liquid at a volume ratio of 5-10%, and fermenting aerobically at 36-38° C. for 24-36 hours; after the fermentation is completed, cooling the fermentation liquid to below 10° C.;

[0022] (4) Add sterilized oligofructose and mix evenly to a final concentration of 10-15 g / L; aseptically fill, package, and store in a refrigerator at 2-10° C. to obtain a fresh corn fermented beverage.

[0023] Further preferably, the method for preparing the fresh corn fermented beverage comprises the following steps:

[0024] (1) fresh corn is cleaned and threshed, and the corn cobs are discarded to obtain fresh corn kernels; the fresh corn kernels and purified water are added into a colloid mill in a mass ratio of 1:4, crushed and homogenized, and filtered to obtain fresh corn pulp;

[0025] (2) Add appropriate amount of water to the fermentation tank, add fresh corn syrup, skim milk powder, K 2 HPO 4 , KH 2 PO 4 MgSO 4 After stirring and dissolving, the volume was fixed to obtain a fermentation medium, in which the contents of each component were 90 g / L fresh corn steep liquor, 115 g / L skim milk powder, and K 2 HPO 4 27g / L, KH 2 PO 4 18g / L, MgSO 4 22g / L; the initial pH value of the culture medium is 5.5-6.5; high-temperature steam is used to control the pressure in the fermenter to 0.09-0.10MPa, the temperature is controlled at 115℃-121℃, sterilize for 25-45min, and then cool down to 37℃;

[0026] (3) inoculating Lactobacillus casei KDB-LC seed liquid into the fermentation medium at a volume ratio of 8%, and incubating at 33° C. in a closed culture for 22 h, and then inoculating Bacillus coagulans KDB-18 seed liquid at a volume ratio of 6%, and fermenting aerobically at 38° C. for 35 h; after the fermentation is completed, cooling the fermentation liquid to below 10° C.;

[0027] (4) Add sterilized oligofructose and mix well to a final concentration of 12 g / L; aseptically fill, package, and store at 2-10°C.

[0028] Beneficial effects of the present invention:

[0029] The fresh corn fermented beverage prepared by the probiotic two-step fermentation method of the present invention is dark brown or brownish yellow, uniform and without stratification, sweet and sour in taste, with a strong corn flavor, and a sensory evaluation of up to 90 points; the pH value is 3.2-4.5, and the number of live bacteria at the factory exceeds 10 11 CFU / mL, and the number of viable bacteria can still maintain 10 after 6 months of storage at room temperature. 10 CFU / mL level, strong storage stability.

[0030] The fresh corn fermented beverage does not contain starch, but is rich in organic acids and polysaccharides, wherein the lactic acid content reaches 6.72-7.26 g / L, the acetic acid content reaches 5.04-5.77 g / L, and the polysaccharide content reaches 2.88-3.32 g / L, achieving unexpected technical effects.

[0031] The fresh corn fermented beverage has a scavenging rate of 85.01%-87.33% for DPPH free radicals, 73.21%-75.25% for hydroxyl free radicals and 82.26%-83.51% for superoxide anions, respectively, has a significant antioxidant effect and achieves unexpected technical effects.

[0032] In summary, the fresh corn fermented beverage provided by the present invention has a sweet and sour taste, has a corn aroma, is rich in organic acids and polysaccharides, has a high content of live bacteria, has the effects of regulating intestinal health, enhancing the body's immunity, and anti-oxidation, is beneficial to promoting physical health, and has broad market prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is the colony morphology of Bacillus coagulans KDB-18. DETAILED DESCRIPTION

[0034] The following examples are provided to better illustrate the present invention, and those skilled in the art can better understand and grasp the present invention with the help of the examples. However, the protection and claims of the present invention are not limited to the examples provided.

[0035] The Lactobacillus casei KDB-LC selected in the embodiment of the present invention was screened from naturally fermented sauerkraut juice collected from Sujiatun Rural Area in Shenyang, and was deposited in the China Type Culture Collection of Wuhan University, Wuhan, China on August 29, 2016, with a deposit number of CCTCC NO: M2016431.

[0036] The Bacillus coagulans KDB-18 selected in the embodiment of the present invention was screened from naturally fermented soybean paste and was deposited in the China Type Culture Collection of Wuhan University, Wuhan, China on July 1, 2024, with a preservation number of CCTCC NO: M20241408.

[0037] The present invention will be further described below in conjunction with the accompanying drawings and specific implementation methods so that those skilled in the art can better understand the present invention, but the present invention is not limited thereto.

[0038] Example 1 Isolation, screening, identification and performance analysis of Bacillus coagulans KDB-18

[0039] The present invention isolates and screens a mucilage- and sugar-producing Bacillus from a naturally fermented soybean paste sample in Huacun Village, Dalian, and the extracellular crude polysaccharide yield in the fermentation broth reaches 3.64 g / L. Combined with the colony morphology, physiological and biochemical characteristics and molecular biological identification results of the Bacillus, it is determined to be a new type of coagulant Bacillus, named Bacillus coagulans KDB-18, which has been deposited in the China Type Culture Collection of Wuhan University, Wuhan, China on July 1, 2024, and its deposit number is CCTCC NO: M20241408.

[0040] The colony morphology of the Bacillus coagulans KDB-18 is as follows Figure 1 As shown, the diameter of a single colony is 2-3mm, white and shiny, with a moist, flat surface and neat edges. Observation under a microscope shows that the strain is rod-shaped, arranged singly, in pairs or chains, and the spores are terminal. The strain is sensitive to common antibiotics such as erythromycin, gentamicin, tetracycline, and ampicillin, and has good biosafety.

[0041] The bacillus coagulans KDB-18 has a strong antioxidant capacity, and the scavenging rates of the supernatant thereof on DPPH free radicals, hydroxyl free radicals and superoxide anions reach 89.35%, 70.19% and 80.56% respectively.

[0042] The Bacillus coagulans KDB-18 can efficiently remove cholesterol, with an in vitro removal rate of up to 85.21%.

[0043] Example 2 Analysis of antibacterial ability of Bacillus coagulans KDB-18

[0044] Staphylococcus aureus, Escherichia coli, Shigella, and Salmonella were inoculated into LB liquid culture medium at a volume ratio of 1%, and then cultured at 37°C for 12 h. The suspension of pathogenic bacteria was adjusted to 10% with sterile saline. 6 -10 7 CFU / mL.

[0045] The activated Bacillus coagulans KDB-18 was inoculated into LB liquid medium at a volume ratio of 1% and cultured at 37°C for 24 hours. 100 μL of pathogenic bacteria suspension was evenly spread on LB solid medium, a sterile Oxford cup was vertically placed in the solid medium and punched, then taken out, 200 μL of Bacillus coagulans KDB-18 fermentation liquid was added to the hole, and a commercially available Bacillus coagulans was used as a control, cultured at 37°C for 24 hours, and the diameter of the inhibition zone was measured. The experiment was repeated three times and the average value was taken.

[0046] The specific results are shown in Table 1.

[0047] Table 1 Bacillus coagulans KDB-18 antibacterial results

[0048]

[0049]

[0050] It can be seen from the data in Table 1 that compared with commercially available Bacillus coagulans, the Bacillus coagulans KDB-18 provided by the present invention has a stronger inhibitory effect on four pathogenic bacteria, Staphylococcus aureus, Escherichia coli, Salmonella and Shigella, and the diameters of the inhibition zones for Escherichia coli and Salmonella are as high as 28.32 and 31.43 mm, respectively, achieving unexpected technical effects.

[0051] Example 3 Analysis of protease production ability of Bacillus coagulans KDB-18

[0052] The activated Bacillus coagulans KDB-18 was inoculated into LB liquid culture medium, and cultured at 37°C and 160 rpm for 24 hours; centrifuged at 4°C and 12000 rpm for 15 minutes, and the supernatant was collected.

[0053] The protease activity of the obtained fermentation supernatant was determined by referring to Appendix B "Determination of protease activity by Folin method" in the national standard GB / T 23527-2009 "Protease preparations".

[0054] The test results show that the protease activity in the fermentation supernatant of Bacillus coagulans KDB-18 provided by the present invention reaches 358.8 U / mL, achieving an unexpected technical effect.

[0055] Example 4 Evaluation of in vitro hypoglycemic activity of Bacillus coagulans KDB-18

[0056] In this example, α-amylase and glucosidase inhibition experiments were used to evaluate the in vitro hypoglycemic activity of Bacillus coagulans KDB-18. The inhibition rates of α-amylase and glucosidase of the fermentation supernatant of Bacillus coagulans KDB-18 were determined according to the instructions of the kit.

[0057] The results showed that the inhibition rates of Bacillus coagulans KDB-18 on α-amylase and glucosidase were 82.28% and 34.06%, respectively, indicating that the Bacillus coagulans KDB-18 provided by the present invention has high in vitro hypoglycemic activity, has potential application prospects in hypoglycemic treatment, and has achieved unexpected technical effects.

[0058] Example 5 Effect of Bacillus coagulans KDB-18 on intestinal health of mice

[0059] The experimental animals were Kunming male mice, 5 weeks old, weighing (22±3) g.

[0060] The mice used in this example were acclimatized to the environment for one week before the experiment. The temperature was 23±2°C and the humidity was 50%.

[0061] ±10%, 12h light-dark cycle, normal supply of drinking water and diet.

[0062] The experimental mice were randomly divided into 3 groups, namely normal control group, Escherichia coli group and Bacillus coagulans KDB-18 group, with 10 mice in each group. The mice were fasted for 24 hours before the experiment. The treatment methods of mice in each group are as follows:

[0063] The mice in the E. coli group and the Bacillus coagulans KDB-18 group were gavaged with 400 μL of an equal proportion of E. coli O157 and E. coli H7 suspension (10 9 After the inflammation model was successfully established, the mice in the E. coli group were gavaged with 400 μL of normal saline daily, and the mice in the Bacillus coagulans KDB-18 group were gavaged with 400 μL of Bacillus coagulans KDB-18 suspension daily (10 8 CFU / mL) for 5 consecutive days. The mice in the normal control group were gavaged with 400 μL of normal saline every day.

[0064] During the experiment, mice were free to eat and drink water, and their body weight and food intake were measured every day.

[0065] After the experiment, the mice were fasted for 12 h and then killed by anesthesia.

[0066] Blood was collected from the eyeballs of all mice and centrifuged at 4°C and 3500 rpm for 15 minutes to obtain serum. The enzyme-linked immunosorbent assay (ELISA) method was used to detect the expression of biochemical indicators and inflammatory factors in the serum of mice in each group.

[0067] Colon tissues were collected from all mice, and feces in the cecal contents were collected. The feces and ether were mixed in a 1:1 ratio, vortexed for 2 minutes, ultrasonicated for 3 minutes to extract short-chain fatty acids, centrifuged for 10 minutes to remove the precipitate, and the supernatant was passed through a 0.22-micron organic filter membrane, wrapped with a sealing film and stored in a -20°C refrigerator for determination. A short-chain fatty acid standard curve was prepared using a gas chromatograph to determine the content of short-chain fatty acids in the cecal contents of mice in different groups.

[0068] 1. Effect of Bacillus coagulans KDB-18 on the body weight of mice

[0069] Compared with the normal control group, the body weight of mice in the Escherichia coli group was significantly reduced, and the body weight of mice showed a significant decline on the 4th day, while the body weight of mice in the Bacillus coagulans KDB-18 group was significantly higher than that in the Escherichia coli group.

[0070] 2. Regulatory effect of Bacillus coagulans KDB-18 on immune response in mice

[0071] Compared with the normal control group, the concentrations of pro-inflammatory factors IL-6, TNF-α, IL-1β, and C-reactive protein in the serum of mice in the E. coli group were significantly increased; while the concentrations of IL-1β, IL-6, and TNF-α in the serum of mice in the Bacillus coagulans KDB-18 group were significantly lower than those in the E. coli group. This shows that the Bacillus coagulans KDB-18 provided by the present invention can effectively reduce the expression of pro-inflammatory factors in the serum of mice, reduce the level of C-reactive protein, and effectively enhance the body immunity of mice.

[0072] 3. Effects of Bacillus coagulans KDB-18 on the level of short-chain fatty acids (SCFAs) in the cecum of mice

[0073] Compared with the normal control group, the contents of acetic acid, propionic acid and butyric acid in the cecal contents of the Escherichia coli group mice were significantly reduced, while the contents of three short-chain fatty acids, acetic acid, propionic acid and butyric acid, in the cecal contents of the Bacillus coagulans KDB-18 group were increased by 88.6%, 60.2% and 130.3% respectively compared with the Escherichia coli group. It is thus shown that the Bacillus coagulans KDB-18 provided by the present invention can significantly increase the content of short-chain fatty acids in the intestine of mice, which is beneficial to promote digestion and absorption, improve the body's anti-inflammatory level, maintain intestinal health, and achieve unexpected technical effects.

[0074] In summary, the Bacillus coagulans KDB-18 obtained by the present invention is sensitive to common antibiotics, has good biosafety, strong resistance to the gastrointestinal environment, can produce high amounts of extracellular polysaccharides and proteases, has strong antibacterial and antioxidant abilities, can efficiently degrade cholesterol, and lower blood sugar. Animal experimental results show that the strain can effectively reduce the expression of pro-inflammatory factors in mouse serum and significantly increase the content of short-chain fatty acids in the intestine, thereby promoting digestion and absorption, improving the body's anti-inflammatory level and immunity, and maintaining intestinal health.

[0075] Example 6 A fresh corn fermented beverage and its preparation method

[0076] A fresh corn fermented beverage is prepared by the following steps:

[0077] (1) fresh corn is cleaned and threshed, and corn cobs are discarded to obtain fresh corn kernels; fresh corn kernels and purified water are added into a colloid mill in a mass ratio of 1:2, crushed and homogenized, and filtered to obtain fresh corn pulp;

[0078] (2) Add appropriate amount of water to the fermentation tank, add fresh corn syrup, skim milk powder, K 2 HPO 4 , KH 2 PO 4 MgSO 4After stirring and dissolving, the volume was fixed to obtain a fermentation medium, in which the contents of each component were 80 g / L fresh corn steep liquor, 120 g / L skim milk powder, and K 2 HPO 4 25g / L, KH 2 PO 4 25g / L, MgSO 4 20g / L; the initial pH value of the culture medium is 5.5-6.5; high-temperature steam is used to control the pressure in the fermenter to 0.09-0.10MPa, the temperature is controlled at 115℃-121℃, sterilize for 25-45min, and then cool down to 37℃;

[0079] (3) inoculating Lactobacillus casei KDB-LC seed liquid into the fermentation medium at a volume ratio of 5%, and culturing in a closed manner at 35° C. for 18 h, and then inoculating Bacillus coagulans KDB-18 seed liquid at a volume ratio of 10%, and fermenting aerobically at 36° C. for 36 h; after the fermentation is completed, cooling the fermentation liquid to below 10° C.;

[0080] (4) Add sterilized oligofructose and mix well to a final concentration of 15 g / L; aseptically fill, package, and store at 2-10°C.

[0081] Example 7 A fresh corn fermented beverage and its preparation method

[0082] A fresh corn fermented beverage is prepared by the following steps:

[0083] (1) fresh corn is cleaned and threshed, and corn cobs are discarded to obtain fresh corn kernels; fresh corn kernels and purified water are added into a colloid mill in a mass ratio of 1:5, crushed and homogenized, and filtered to obtain fresh corn pulp;

[0084] (2) Add appropriate amount of water to the fermentation tank, add fresh corn syrup, skim milk powder, K 2 HPO 4 , KH 2 PO 4 MgSO 4 After stirring and dissolving, the volume was fixed to obtain a fermentation medium, in which the contents of each component were 95 g / L fresh corn steep liquor, 100 g / L skim milk powder, and K 2 HPO 4 30g / L, KH 2 PO 4 15g / L, MgSO 4 30g / L; the initial pH value of the culture medium is 5.5-6.5; high-temperature steam is used to control the pressure in the fermenter to 0.09-0.10MPa, the temperature is controlled at 115℃-121℃, sterilize for 25-45min, and then cool down to 37℃;

[0085] (3) inoculating Lactobacillus casei KDB-LC seed liquid into the fermentation medium at a volume ratio of 10%, and culturing in a closed manner at 35° C. for 24 h, and then inoculating Bacillus coagulans KDB-18 seed liquid at a volume ratio of 5%, and fermenting aerobically at 38° C. for 24 h; after the fermentation is completed, cooling the fermentation liquid to below 10° C.;

[0086] (4) Add sterilized oligofructose and mix well to a final concentration of 10 g / L; aseptically fill, package, and store at 2-10°C.

[0087] Example 8 A fresh corn fermented beverage and its preparation method

[0088] A fresh corn fermented beverage is prepared by the following steps:

[0089] (1) fresh corn is cleaned and threshed, and the corn cobs are discarded to obtain fresh corn kernels; the fresh corn kernels and purified water are added into a colloid mill in a mass ratio of 1:4, crushed and homogenized, and filtered to obtain fresh corn pulp;

[0090] (2) Add appropriate amount of water to the fermentation tank, add fresh corn syrup, skim milk powder, K 2 HPO 4 , KH 2 PO 4 MgSO 4 After stirring and dissolving, the volume was fixed to obtain a fermentation medium, in which the contents of each component were 90 g / L fresh corn steep liquor, 115 g / L skim milk powder, and K 2 HPO 4 27g / L, KH 2 PO 4 18g / L, MgSO 4 22g / L; the initial pH value of the culture medium is 5.5-6.5; high-temperature steam is used to control the pressure in the fermenter to 0.09-0.10MPa, the temperature is controlled at 115℃-121℃, sterilize for 25-45min, and then cool down to 37℃;

[0091] (3) inoculating Lactobacillus casei KDB-LC seed liquid into the fermentation medium at a volume ratio of 8%, and incubating at 33° C. in a closed culture for 22 h, and then inoculating Bacillus coagulans KDB-18 seed liquid at a volume ratio of 6%, and fermenting aerobically at 38° C. for 35 h; after the fermentation is completed, cooling the fermentation liquid to below 10° C.;

[0092] (4) Add sterilized oligofructose and mix well to a final concentration of 12 g / L; aseptically fill, package, and store at 2-10°C.

[0093] Example 9 Performance Analysis of Fresh Corn Fermented Beverage

[0094] The fresh corn fermented beverages prepared in Examples 6-8 of the present invention were subjected to sensory evaluation, pH value determination, and organic acid, starch, viable bacteria count, and polysaccharide content determination, and their antioxidant properties were evaluated. The fresh corn fermented beverage was centrifuged at 4° C. and 12,000 rpm for 15 minutes to obtain a supernatant.

[0095] 1. Sensory evaluation

[0096] The sensory evaluation method for fresh corn fermented beverages is to randomly invite 10 young people aged 18-25 to serve as tasters, formulate a sensory evaluation form according to the agricultural industry standard NY / T434-2016 of the People's Republic of China, and provide each person with a sample for tasting. After tasting a sample, rinse your mouth, rest for one minute, and then taste the next sample to avoid overlapping tastes and the risk of sensory dullness due to continuous tasting of beverages with similar flavors. The score is 100 points, subtract one high score and one low score to get the average score. The evaluation criteria are scored according to Table 2.

[0097] Table 2 Sensory evaluation standards

[0098]

[0099]

[0100] The sensory evaluation of the fresh corn fermented beverages prepared in Examples 6-8 was performed with reference to the above method.

[0101] The results showed that the fresh corn fermented beverage provided by the present invention was dark brown or brownish yellow in color, tasted sweet and sour, had a strong corn aroma, normal viscosity, was a uniform liquid, and had a sensory score higher than 87 points. Among them, the fresh corn fermented beverage prepared in Example 8 had the highest score of 90 points, achieving unexpected results.

[0102] 2. pH value

[0103] The pH value of the supernatant of fresh corn fermented beverage was measured using a handheld pH meter.

[0104] The results showed that the pH value of the fresh corn fermented beverage provided by the present invention was 3.2-4.5.

[0105] 3. Organic acid content

[0106] The organic acid content in the supernatant of fresh corn fermented beverage was detected by high performance liquid chromatography, the detector was an ultraviolet detector, and the determination conditions were: wavelength 210nm; mobile phase: 0.1% phosphoric acid aqueous solution. Blank RCM culture medium was filtered through a 0.22μm filter before loading as a blank control group.

[0107] The results showed that the lactic acid content in the fresh corn fermented beverage provided by the present invention was 6.72-7.26 g / L, and the acetic acid content was 5.04-5.77 g / L.

[0108] 3. Starch content and live bacteria content

[0109] The method described in GB 5009.9-2016 was used to detect the starch content in the supernatant of fresh corn fermented beverages. The plate count method was used to detect the number of viable bacteria (CFU / mL) in fresh corn fermented beverages.

[0110] The results show that the starch content of the fresh corn fermented beverage provided by the present invention is 0, and the number of live bacteria leaving the factory is more than 10 11 CFU / mL, and the number of viable bacteria can still maintain 10 after 6 months of storage at room temperature. 10 The level of CFU / mL is stable.

[0111] 4. Polysaccharide content

[0112] Add at least 3 times the volume of anhydrous ethanol to the supernatant of fresh corn fermented beverage, let it stand, centrifuge, and collect the precipitate, which is the crude extracellular polysaccharide.

[0113] The crude extracellular polysaccharide was washed with 95% ethanol by volume, centrifuged at about 10,000 rpm and 4°C for 15 minutes, the supernatant was discarded, and the precipitate was washed again with 95% ethanol by volume, centrifuged at about 10,000 rpm and 4°C for 15 minutes, the supernatant was discarded, and the final precipitate was dissolved in 85°C distilled water. After removing the protein in the crude polysaccharide using the Sevage method, pure water was used as the dialysate in a dialysis bag with a molecular weight cutoff of 7000 for 48 hours, and the dialysate was replaced every 12 hours. The polysaccharide solution in the dialysis bag was freeze-dried using a freeze dryer. The freeze dryer had a condensation temperature of -40°C, a vacuum degree of 20 Pa, and a freezing time of about 20 hours to obtain dry powdered extracellular polysaccharides.

[0114] The results showed that the extracellular polysaccharide content in the fresh corn fermented beverage provided by the present invention reached 2.88-3.32 g / L.

[0115] 4. Antioxidant capacity analysis

[0116] The scavenging ability of the supernatant of fresh corn fermented beverage on DPPH free radicals, hydroxyl free radicals and superoxide anions was measured respectively to indicate the comprehensive antioxidant capacity of the beverage.

[0117] (1) DPPH free radical scavenging rate

[0118] 2 mL of the supernatant of the fresh corn fermented beverage was thoroughly mixed with 2 mL of 0.2 mmol / L DPPH 95% ethanol solution, respectively, and then placed at room temperature for 30 minutes, and the absorbance was measured at 517 nm.

[0119] DPPH free radical scavenging rate = (1-(A 1 -A 2 ) / A 3 )×100%.

[0120] Where: A 1 A is the absorbance value measured by the reaction between DPPH solution and sample; 2 A is the absorbance value measured when 95% ethanol replaces DPPH solution and reacts with the sample; 3 It is the absorbance value measured when distilled water replaces the sample and reacts with DPPH solution.

[0121] (2) Hydroxyl free radical scavenging rate:

[0122] The operation was carried out according to the instructions of the hydroxyl free radical determination kit (Fenton colorimetric method), the absorbance was measured at 550 nm and the scavenging ability of the fermentation supernatant of the strain on hydroxyl free radicals was calculated.

[0123] (3) Superoxide anion clearance rate:

[0124] The superoxide anion scavenging ability of the strain was determined by the pyrogallol auto-oxidation method. 1 mL of 150 mmol / L Tris-HCl (pH 8.2), 1.2 mmol / L pyrogallol and 3 mmol / L diethylenetriaminepentaacetic acid were added to the sample, kept at 25°C for 10 min, and the absorbance was measured at 325 nm.

[0125] The calculation formula is as follows:

[0126] Superoxide anion clearance rate (%) = [1-(A b -A c ) / (A d -A e )]×100%.

[0127] Where: A b is the absorbance value without sample and pyrogallol; A c A is the absorbance value without sample and containing pyrogallol; d A is the absorbance value of the sample without pyrogallol; e is the absorbance value of the sample and pyrogallol.

[0128] The above test results show that the fresh corn fermented beverage provided by the present invention has a scavenging rate of 85.01%-87.33% for DPPH free radicals, 73.21%-75.25% for hydroxyl radicals, and 82.26%-83.51% for superoxide anions, respectively, has a significant antioxidant effect, and has achieved unexpected technical effects.

[0129] In summary, the fresh corn fermented beverage provided by the present invention has a sweet and sour taste, has a corn aroma, is rich in organic acids and polysaccharides, has a high content of live bacteria, has the effects of regulating intestinal health, enhancing the body's immunity, and anti-oxidation, is beneficial to promoting physical health, and has broad market prospects.

Claims

1. A fresh corn fermented beverage, characterized in that: The fresh corn fermented beverage contains Lactobacillus casei ( Lactobacillus casei and Bacillus coagulans ( Bacillus coagulans ).

2. The fresh corn fermented beverage according to claim 1, characterized in that: The preservation number of the Lactobacillus casei is CCTCC NO: M2016431.

3. The fresh corn fermented beverage according to claim 1 or 2, characterized in that: The deposit number of the Bacillus coagulans is CCTCC NO: M20241408.

4. The method for preparing the fresh corn fermented beverage according to claim 3, characterized in that: The preparation method comprises the following steps: (1) preparing fresh corn steep liquor; (2) preparing a fermentation medium containing fresh corn steep liquor, sterilizing it, and cooling it; (3) Inoculate the Lactobacillus casei seed liquid into the fermentation medium, culture it in a closed environment at 30-35°C for 18-24 hours, then inoculate the Bacillus coagulans seed liquid, and ferment it aerobically at 36-38°C for 24-36 hours; after the fermentation is completed, cool the fermentation liquid to below 10°C; (4) Add prebiotics to the fermentation liquid, perform aseptic filling and packaging, and obtain a fresh corn fermented beverage.

5. The method for preparing the fresh corn fermented beverage according to claim 4, characterized in that: The fermentation medium in step (2) contains fresh corn steep liquor, skimmed milk powder, K2HPO4, KH2PO4 and MgSO4.

6. The method for preparing the fresh corn fermented beverage according to claim 5, characterized in that: The components and their mass volume ratios in the fermentation medium in step (2) are: fresh corn syrup 80-95 g / L, skim milk powder 100-120 g / L, K2HPO4 25-30 g / L, KH2PO4 15-25 g / L, and MgSO4 20-30 g / L.

7. The method for preparing a fresh corn fermented beverage according to claim 5 or 6, characterized in that: The prebiotics in step (4) are oligofructose.

8. The method for preparing the fresh corn fermented beverage according to claim 7, characterized in that: The preparation method comprises the following steps: (1) Cleaning and threshing fresh corn, discarding corn cobs, and obtaining fresh corn kernels; adding the fresh corn kernels and purified water in a colloid mill at a mass ratio of 1:2-5, crushing and homogenizing, and filtering to obtain fresh corn pulp; (2) Add appropriate amount of water to the fermentation tank, add fresh corn syrup, skim milk powder, K2HPO4, KH2PO4, and MgSO4 respectively, stir to dissolve and then adjust the volume to obtain a fermentation medium, wherein the content of each component is 80-95 g / L of fresh corn syrup, 100-120 g / L of skim milk powder, 25-30 g / L of K2HPO4, 15-25 g / L of KH2PO4, and 20-30 g / L of MgSO4; the initial pH value of the medium is 5.5-6.5; use high-temperature steam to control the pressure in the fermentation tank to 0.09-0.10 MPa, control the temperature at 115℃-121℃, sterilize for 25-45 minutes, and cool down to 37℃ after completion; (3) Inoculate the Lactobacillus casei seed liquid into the fermentation medium at a volume ratio of 5-10%, and culture it in a closed environment at 30-35°C for 18-24 hours; then inoculate the Bacillus coagulans seed liquid at a volume ratio of 5-10%, and ferment it aerobically at 36-38°C for 24-36 hours; after the fermentation is completed, cool the fermentation liquid to below 10°C; (4) Add sterilized oligofructose and mix evenly to a final concentration of 10-15 g / L; aseptically fill, package, and store in a refrigerator at 2-10°C to obtain a fresh corn fermented beverage.

9. The method for preparing the fresh corn fermented beverage according to claim 8, characterized in that: The preparation method comprises the following steps: (1) Cleaning and threshing fresh corn, discarding corn cobs, and obtaining fresh corn kernels; adding the fresh corn kernels and purified water in a colloid mill at a mass ratio of 1:4, crushing and homogenizing, and filtering to obtain fresh corn pulp; (2) Add appropriate amount of water to the fermentation tank, add fresh corn syrup, skim milk powder, K2HPO4, KH2PO4, and MgSO4 respectively, stir to dissolve and then adjust the volume to obtain a fermentation medium, wherein the content of each component is 90 g / L fresh corn syrup, 115 g / L skim milk powder, 27 g / L K2HPO4, 18 g / L KH2PO4, and 22 g / L MgSO4; the initial pH value of the medium is 5.5-6.5; use high-temperature steam to control the pressure in the fermentation tank to 0.09-0.10 MPa, control the temperature at 115℃-121℃, sterilize for 25-45 minutes, and then cool to 37℃; (3) Inoculate the Lactobacillus casei KDB-LC seed liquid into the fermentation medium at a volume ratio of 8%, culture it in a closed environment at 33°C for 22 hours, then inoculate the Bacillus coagulans KDB-18 seed liquid at a volume ratio of 6%, and ferment it aerobically at 38°C for 35 hours; after the fermentation is completed, cool the fermentation liquid to below 10°C; (4) Add sterilized oligofructose and mix evenly to a final concentration of 12 g / L; aseptically fill, package, and store in a refrigerator at 2-10°C to obtain a fresh corn fermented beverage.

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