Corn juice composite beverage and preparation method thereof

Abstract

The invention relates to the technical field of beverage processing, in particular to a corn juice compound beverage and a preparation method thereof. The feed comprises the following raw materials: corn, black rice, oat, carrots, corncob powder, orange peel, compound enzyme, beta-cyclodextrin, Arabic gum, inulin, a yeast extract, monopotassium phosphate, vitamin B and compound strains. The compound enzyme seed is prepared from the following components: alpha-amylase, pullulanase, tannase and neutral protease; the composite strain is prepared from the following components: saccharomycetes, lactobacillus plantarum and monascus purpureus. According to the corn juice composite beverage and the preparation method thereof, through multi-dimensional synergistic interaction, the beverage realizes a layering flavor with both freshness, fruity flavor and cereal sweetness and fragrance, an anti-oxidation network constructed by polyphenol, carotenoid and ferulic acid and an intestinal tract nursing effect brought by complementation of soluble-insoluble fibers form the corn juice composite beverage with functional value and sensory experience.

Description

Technical Field

[0001] The present invention relates to the technical field of beverage processing, and particularly relates to a corn juice composite beverage and a preparation method thereof. Background Art

[0002] As the world's highest-yielding C4 grass crop, the unique physiological structure and chemical components of corn endow it with irreplaceability in the field of food deep processing. From a histological perspective, corn kernels consist of an endosperm, germ, and seed coat to form a three-dimensional composite system. The endosperm is rich in amylose / amylopectin and prolamin, forming a unique semi-crystalline granule structure. This tightly packed carbohydrate-protein complex is difficult to fully dissolve in conventional water extraction processes but provides a slow-release carbon source for microbial fermentation. The germ, as the part with the highest nutritional density in the whole grain, not only contains functional oils (rich in tocopherols, phytosterols, and linoleic acid), but its glutathione peroxidase also confers natural oxidative stability. The seed coat layer aggregates the main dietary fibers of corn, β-glucan and arabinoxylan, and its reticular fiber structure forms micron-sized pores after mechanical fragmentation, constructing an ideal biological reaction interface for bacterial colonization.

[0003] In the traditional field of corn beverage processing, processes such as physical crushing, high-temperature gelatinization, or enzymatic saccharification are usually used to prepare corn juice. Although these methods can achieve the functions of basic beverages, they have significant limitations in terms of nutrient retention, flavor enhancement, and function expansion. Existing technologies mostly rely on high-temperature sterilization to ensure the product shelf life, resulting in a large loss of heat-sensitive active ingredients in corn (such as vitamin B group, γ-aminobutyric acid, and phenolic substances). At the same time, high-temperature treatment is prone to cause the Maillard reaction, making the beverage produce a burnt smell and masking the natural sweetness of corn. In addition, the utilization rate of dietary fiber and germ protein in parts such as corn germ and seed coat by conventional processes is insufficient, and solid substances are often removed by filtration, resulting in waste of resources and nutritional deficiencies. Mainstream corn beverages on the market generally have the problems of bland taste and single flavor. To make up for the defects, sucrose, flavorings, and stabilizers are often added, which not only does not conform to the clean label consumption trend but also weakens the health value of corn as a whole grain raw material. Moreover, under existing technologies, corn fermentation has problems such as poor stability, easy stratification and precipitation, serious nutrient loss, and easy oxidation resulting in appearance defects. Therefore, based on the above problems, it is extremely necessary to utilize the advantages of corn in the fermentation field and combine fermentation technology to prepare a nutritious, rich-tasting corn juice composite beverage without chemical preservatives. Summary of the Invention

[0004] Aiming at the defects of the existing technology, the purpose of the present invention is to provide a corn juice composite beverage and a preparation method thereof.

[0005] The technical effects of the present invention are achieved through the following technical solutions: A corn juice composite beverage, the composition of which includes the following raw materials by weight: 30-40 parts of corn, 5-8 parts of black rice, 4-7 parts of oats, 8-12 parts of carrots, 1-3 parts of corn cob powder, 0.5-1.5 parts of orange peel, 0.4-0.6 parts of composite enzyme species, 0.3-0.5 parts of β-cyclodextrin, 0.1-0.2 parts of arabic gum, 1-2 parts of inulin, 0.05-0.15 parts of yeast extract, 0.02-0.04 parts of potassium dihydrogen phosphate, 0.001-0.003 parts of vitamin B, and 0.25-0.4 parts of composite bacterial species.

[0006] Preferably, the corn consists of 95% corn kernels and 5% corn silk; Preferably, the corn cob powder is obtained by crushing corn cobs and screening through a 200-mesh sieve; Preferably, the composition of the composite enzyme species includes the following components by weight: 0.15-0.25 parts of α-amylase, 0.07-0.12 parts of pullulanase, 0.03-0.05 parts of tannase, and 0.05-0.08 parts of neutral protease; the α-amylase has an activity of 18000 U / g; the pullulanase has an activity of 2200 U / g; the tannase has an activity of 1000 U / g; the neutral protease has an activity of 65000 U / g; Preferably, the composition of the composite bacterial species includes the following components by weight: 0.07-0.1 parts of yeast, 0.15-0.25 parts of Lactobacillus plantarum, and 0.03-0.05 parts of Monascus purpureus; the inoculation activity of the yeast is 1×10 9 ~1×10 10 CFU / g; the inoculation activity of the Lactobacillus plantarum is 1×10 10 ~5×10 10 CFU / g; the inoculation activity of the Monascus purpureus is 1×10 8 ~5×10 8 CFU / g; Preferably, on the other hand, the present invention provides a preparation method of a corn juice composite beverage, and the specific preparation steps are as follows: S1: After cleaning the corn, add it to water and boil it under normal pressure for 15-30 min, then steam it at 0.15 MPa for 20-30 min, naturally depressurize and keep it for 10-20 min, and cool it to 60 °C at a rate of 5 °C / min to obtain pretreated corn and corn cooking water; S2: Soak black rice in 0.5wt% citric acid solution for 2 - 3 h. After filtering and draining, mix it with oatmeal and treat at 60 °C for 10 min, then heat up to 85 °C at a rate of 5 °C / min and treat for 15 - 30 min. Grind and sieve through a 300 - mesh sieve to obtain pretreated black rice - oatmeal; S3: Dice carrots and mix them evenly with the corn cooking water prepared in step S1. Rotate and bake at 120 °C for 12 - 15 min, then filter and drain to obtain pretreated carrots; Air - dry orange peel at 50 °C until the water content is less than 8% to obtain pretreated orange peel; S4: Add the pretreated corn prepared in step S1, the pretreated black rice - oatmeal prepared in step S2, the pretreated carrots and pretreated orange peel prepared in step S3, α - amylase, pullulanase, neutral protease and tannase into a fermenter for staged fermentation. After the staged fermentation is completed, heat up to 85 - 90 °C for inactivation treatment for 10 - 15 min, immediately cool to 35 °C, and sieve through a 120 - mesh sieve to obtain an enzymolysis solution; S5: Add yeast, Lactobacillus plantarum, corncob powder, Monascus purpureus, yeast extract, potassium dihydrogen phosphate and vitamin B into the enzymolysis solution prepared in step S4 for staged fermentation to obtain a fermentation broth; S6: Add β - cyclodextrin and arabic gum into the fermentation broth prepared in step S5, stir for 1 - 2 h, sieve through a 100 - mesh sieve and then through a 200 - mesh sieve, perform homogenization treatment, maintain at 72 °C for 15 - 30 s for pasteurization treatment, and quickly cool to 25 °C in an ice bath to obtain a corn juice compound beverage; Preferably, in step S4, the specific operation of the staged fermentation is as follows: Add the pretreated corn prepared in step S1, α - amylase and pullulanase into a fermenter, adjust the pH to 5.8 - 6.2, ferment at 55 - 60 °C for 10 - 20 min, then add the pretreated black rice - oatmeal prepared in step S2 and continue to ferment for 20 - 30 min; Then add the carrots prepared in step S3, adjust the pH to 7, reduce the temperature to 45 - 50 °C at a rate of 0.5 °C / min, and ferment for 30 - 50 min; Then add tannase and the pretreated orange peel prepared in step S3, adjust the pH to 5.5, and continue to ferment for 30 - 50 min; Preferably, in step S5, the specific operation of the staged fermentation is as follows: Add yeast, Monascus purpureus, ammonium sulfate, potassium dihydrogen phosphate and vitamin B into the enzymolysis solution prepared in step S4, control the temperature to 28 °C, charge dissolved oxygen at 8 - 10 mg / L, ferment for 16 - 24 h, then add Lactobacillus plantarum and corncob powder, heat up to 37 °C, and ferment under anaerobic conditions for 24 - 30 h; Preferably, in step S6, the specific operation of the homogenization treatment is as follows: homogenization treatment is performed once at 25 MPa and then once at 40 MPa.

[0007] The beneficial effects of the present invention are as follows: Through the functional synergy of raw material components and the synergy of process stages, the present invention constructs a multi-level synergistic effect system. First, the slight bitterness of limonene in orange peel forms a sweet-bitter balance with the natural reducing sugars in corn and carrots; terpene substances (such as linalool) in orange peel essential oil react with ethanol produced by yeast metabolism in an acidic fermentation environment to generate floral and fruity ester compounds such as linalyl acetate, and the pyrazine and furanone precursors formed by soluble amino acids in corn cooking water and carrot reducing sugars under high-temperature and humid heat treatment are superimposed, and the aromas are intertwined, giving the drink a fresh and baked composite flavor and effectively masking the fishy smell of corn starch and the green smell of carrots. Secondly, orange peel flavonoids (hesperidin, nobiletin) and black rice anthocyanins, zeaxanthin and β-carotene produce an additive antioxidant effect at the hydroxyl hydrogen-donating and conjugated double bond sites; the free ferulic acid released during the enzymatic hydrolysis-fermentation process binds to the phenolic hydroxyl group of anthocyanins through hydrogen bonds to form a molecular complex to delay the degradation of anthocyanins and increase the free radical scavenging rate, constructing a composite polyphenol-carotenoid antioxidant network. In terms of digestion and conditioning, the soluble pectin in orange peel complements the insoluble fiber in corn cob powder and oat β-glucan, and can produce short-chain fatty acids in the colon segment to maintain the intestinal microecology; the lactic acid generated by fermentation and the citric acid in orange peel together constitute a composite acid system to promote the secretion of bile salts, and at the same time rely on the emulsification of the native oil in corn germ to improve the micellization rate of β-carotene and zeaxanthin, effectively enhancing the bioavailability of fat-soluble nutrients. In terms of physical stability, ferulic acid and β-glucan form a hydrophobic complex at neutral pH to embed amylose and inhibit starch retrogradation; after high-pressure double-stage homogenization, the particle size is effectively controlled, and combined with the encapsulation of volatile aroma by β-cyclodextrin and the charge repulsion provided by arabic gum, a stable and synergistic suspension system is constructed to effectively prevent precipitation and stratification. The tandem high-temperature and medium-temperature α-amylase and pullulanase synergistically deconstruct the cereal starch network to provide oligosaccharide substrates for subsequent microbial utilization; neutral protease directionally cleaves zein in corn to generate taste peptides, and tannase eliminates the astringency of black rice and releases soluble polysaccharides at the final stage; in the co-culture stage of Monascus purpureus-yeast, exogenous amylase continues to degrade residual starch, yeast simultaneously produces esters and imparts the natural color of Monascus purpureus; subsequent anaerobic fermentation of Lactobacillus plantarum preferentially utilizes inulin to produce lactic acid, and β-glucosidase methylates anthocyanins into more stable peonidin-3-glucoside, further consolidating the color and antioxidant properties.

[0008] In summary, through the above multi-dimensional synergistic enhancement, the beverage of the present invention achieves a hierarchical flavor with the coexistence of freshness - fruity aroma - cereal sweet aroma, an antioxidant network constructed by polyphenols - carotenoids - ferulic acid, and an intestinal conditioning effect brought by the complementarity of soluble - insoluble fibers, forming a corn juice composite beverage with both functional value and sensory experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only those of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0010] Figure 1 It is a graph showing the antioxidant test results of the corn juice composite beverages prepared in Example 2 and Comparative Examples 1 - 4 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0011] The following will clearly and completely describe the technical solutions of the present invention in combination with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention. It should be noted that unless otherwise specified, the raw materials involved in the present invention are purchased through conventional commercial channels.

[0012] Example 1: A corn juice composite beverage, the composition of which includes the following raw materials by weight: 30 parts of corn, 5 parts of black rice, 4 parts of oats, 8 parts of carrots, 1 part of corn cob powder, 0.5 part of orange peel, 0.4 part of composite enzyme species, 0.3 part of β - cyclodextrin, 0.1 part of arabic gum, 1 part of inulin, 0.05 part of yeast extract, 0.02 part of potassium dihydrogen phosphate, 0.001 part of vitamin B, and 0.25 part of composite bacterial species.

[0013] The corn consists of 95% corn kernels and 5% corn silk; The corn cob powder is obtained by crushing corn cobs and screening through a 200 - mesh sieve; The composite enzyme species includes the following components by weight: 0.15 part of α - amylase, 0.07 part of pullulanase, 0.03 part of tannase, and 0.05 part of neutral protease; the α - amylase has an activity of 18000 U / g; the pullulanase has an activity of 2200 U / g; the tannase has an activity of 1000 U / g; the neutral protease has an activity of 65000 U / g; The composition of the composite strain includes the following components by weight: 0.07 parts of yeast, 0.15 parts of Lactobacillus plantarum, and 0.03 parts of Monascus purpureus; the inoculation activity of the yeast is 1×10 9 CFU / g; the inoculation activity of the Lactobacillus plantarum is 1×10 10 CFU / g; the inoculation activity of the Monascus purpureus is 1×10 8 CFU / g; The specific preparation steps of the corn juice composite beverage are as follows: S1: After cleaning the corn, add it to water and boil it at normal pressure for 15 min, then steam it at 0.15 MPa for 30 min, naturally depressurize and keep it for 20 min, and cool it to 60 °C at a rate of 5 °C / min to obtain pretreated corn and corn cooking water; S2: Soak the black rice in a 0.5 wt% citric acid solution for 3 h, filter and drain it, then mix it with oatmeal and treat it at 60 °C for 10 min, then heat it to 85 °C at a rate of 5 °C / min and treat it for 15 min, grind and sieve it through a 300-mesh sieve to obtain pretreated black rice-oatmeal; S3: Dice the carrots and mix them evenly with the corn cooking water prepared in step S1, rotate and bake them at 120 °C for 12 min, filter and drain them to obtain pretreated carrots; air-dry the orange peel at 50 °C until the water content is less than 8% to obtain pretreated orange peel; S4: Add the pretreated corn, α-amylase, and pullulanase prepared in step S1 to the fermenter, adjust the pH to 6.2, ferment at 60 °C for 10 min, then add the pretreated black rice-oatmeal prepared in step S2 and continue to ferment for 25 min; then add the carrots prepared in step S3, adjust the pH to 7, lower the temperature to 50 °C at a rate of 0.5 °C / min, and ferment for 30 min; then add tannase and the pretreated orange peel prepared in step S3, adjust the pH to 5.5, and continue to ferment for 30 min. After the staged fermentation is completed, heat it to 85 °C for inactivation treatment for 15 min, immediately cool it to 35 °C, and sieve it through a 120-mesh sieve to obtain the enzymolysis solution; S5: Add yeast, Monascus purpureus, yeast extract, potassium dihydrogen phosphate, and vitamin B to the enzymolysis solution prepared in step S4, control the temperature to 28 °C, charge dissolved oxygen at 8 mg / L, ferment for 16 h, then add Lactobacillus plantarum and corn cob powder, heat it to 37 °C, and ferment under anaerobic conditions for 24 h to obtain the fermentation broth; S6: Add β - cyclodextrin and gum arabic into the fermentation broth prepared in step S5, stir for 1 h, sieve through a 100 - mesh sieve, then through a 200 - mesh sieve, homogenize once at 25 MPa, then homogenize once at 40 MPa, and then maintain at 72 °C for 15 s for pasteurization treatment, and quickly cool to 25 °C in an ice bath to obtain the corn juice composite beverage.

[0014] Example 2: A corn juice composite beverage, the composition of which includes the following raw materials by weight: 38 parts of corn, 7.5 parts of black rice, 6 parts of oats, 11 parts of carrots, 2 parts of corn cob powder, 1.3 parts of orange peel, 0.55 part of composite enzyme species, 0.45 part of β - cyclodextrin, 0.18 part of gum arabic, 1.8 parts of inulin, 0.12 part of yeast extract, 0.035 part of potassium dihydrogen phosphate, 0.0025 part of vitamin B, and 0.35 part of composite bacterial species.

[0015] The corn consists of 95% corn kernels and 5% corn silk. The corn cob powder is obtained by crushing corn cobs and sieving through a 200 - mesh sieve. The composite enzyme species consists of the following components by weight: 0.22 part of α - amylase, 0.1 part of pullulanase, 0.04 part of tannase, and 0.07 part of neutral protease; the activity of the α - amylase used is 18000 U / g; the activity of the pullulanase used is 2200 U / g; the activity of the tannase used is 1000 U / g; the activity of the neutral protease used is 65000 U / g. The composite bacterial species consists of the following components by weight: 0.08 part of yeast, 0.2 part of Lactobacillus plantarum, and 0.04 part of Monascus purpureus; the inoculation activity of the yeast is 1×10 10 CFU / g; the inoculation activity of the Lactobacillus plantarum is 5×10 10 CFU / g; the inoculation activity of the Monascus purpureus is 5×10 8 CFU / g. The specific preparation steps of the corn juice composite beverage are as follows: S1: After cleaning the corn, add it to water and boil at normal pressure for 18 min, then steam - press at 0.15 MPa for 25 min, naturally depressurize and keep for 15 min, and cool to 60 °C at a rate of 5 °C / min to obtain pretreated corn and corn cooking water. S2: Soak the black rice in a 0.5 wt% citric acid solution for 2.5 h, filter and drain, then mix with oatmeal and treat at 60 °C for 10 min, then heat up to 85 °C at a rate of 5 °C / min and treat for 20 min, grind and sieve through a 300 - mesh sieve to obtain pretreated black rice - oats. S3: Dice the carrots and mix them evenly with the corn steaming water prepared in step S1. Rotate and bake at 120°C for 13 min, then filter and drain to obtain pretreated carrots; air-dry the orange peel at 50°C until the water content is less than 8% to obtain pretreated orange peel; S4: Add the pretreated corn, α-amylase, and pullulanase prepared in step S1 to the fermentation tank, adjust the pH to 6, and ferment at 58°C for 15 min. Then add the pretreated black rice-oat prepared in step S2 and continue to ferment for 20 min; then add the carrots prepared in step S3, adjust the pH to 7, and reduce the temperature to 47°C at a rate of 0.5°C / min and ferment for 40 min; then add tannase and the pretreated orange peel prepared in step S3, adjust the pH to 5.5, and continue to ferment for 40 min. After the staged fermentation is completed, raise the temperature to 88°C for inactivation treatment for 12 min, immediately cool to 35°C, and screen through a 120-mesh sieve to obtain the enzymolysis solution; S5: Add yeast, Monascus purpureus, yeast extract, potassium dihydrogen phosphate, and vitamin B to the enzymolysis solution prepared in step S4, control the temperature to 28°C, and charge dissolved oxygen at 9 mg / L and ferment for 20 h. Then add Lactobacillus plantarum and corncob powder, raise the temperature to 37°C, and ferment under anaerobic conditions for 27 h to obtain the fermentation broth; S6: Add β-cyclodextrin and arabic gum to the fermentation broth prepared in step S5, stir for 2 h, screen through a 100-mesh sieve, then screen through a 200-mesh sieve, homogenize once at 25 MPa, and then homogenize once at 40 MPa. Then maintain at 72°C for 20 s for pasteurization treatment, and quickly cool to 25°C in an ice bath to obtain the corn juice composite beverage.

[0016] Example 3: A corn juice composite beverage, the composition of which includes the following raw materials by weight: 40 parts of corn, 8 parts of black rice, 7 parts of oats, 12 parts of carrots, 3 parts of corncob powder, 1.5 parts of orange peel, 0.6 part of composite enzyme species, 0.5 part of β-cyclodextrin, 0.2 part of arabic gum, 2 parts of inulin, 0.15 part of yeast extract, 0.04 part of potassium dihydrogen phosphate, 0.003 part of vitamin B, and 0.4 part of composite bacterial species.

[0017] The corn consists of 95% corn kernels and 5% corn silk; The corncob powder is obtained by crushing the corncob and screening through a 200-mesh sieve; The composition of the composite enzyme species includes the following components by weight: 0.25 parts of α-amylase, 0.12 parts of pullulanase, 0.05 parts of tannase, and 0.08 parts of neutral protease; the α-amylase has an activity of 18000 U / g; the pullulanase has an activity of 2200 U / g; the tannase has an activity of 1000 U / g; the neutral protease has an activity of 65000 U / g; The composition of the composite bacterial species includes the following components by weight: 0.1 part of yeast, 0.25 parts of Lactobacillus plantarum, and 0.05 parts of Monascus purpureus; the inoculation activity of the yeast is 5×10 9 CFU / g; the inoculation activity of the Lactobacillus plantarum is 3×10 10 CFU / g; the inoculation activity of the Monascus purpureus is 3×10 8 CFU / g; The specific preparation steps of the corn juice composite beverage are as follows: S1: After cleaning the corn, add it to water and boil it at normal pressure for 30 min, then steam it at 0.15 MPa for 20 min, keep it for 10 min after natural pressure reduction, and cool it to 60 °C at a rate of 5 °C / min to obtain pretreated corn and corn cooking water; S2: Soak the black rice in a 0.5 wt% citric acid solution for 2 h, filter and drain it, then mix it with oatmeal and treat it at 60 °C for 10 min, then heat it to 85 °C at a rate of 5 °C / min and treat it for 30 min, grind and crush it, and sieve it through a 300-mesh sieve to obtain pretreated black rice-oatmeal; S3: Dice the carrots and mix them evenly with the corn cooking water prepared in step S1, roast them at 120 °C for 15 min while rotating, filter and drain to obtain pretreated carrots; air-dry the orange peel at 50 °C until the water content is less than 8% to obtain pretreated orange peel; S4: Add the pretreated corn, α-amylase, and pullulanase prepared in step S1 to the fermentation tank, adjust the pH to 5.8, ferment at 55 °C for 20 min, then add the pretreated black rice-oatmeal prepared in step S2 and continue to ferment for 30 min; then add the carrots prepared in step S3, adjust the pH to 7, reduce the temperature to 45 °C at a rate of 0.5 °C / min, and ferment for 50 min; then add tannase and the pretreated orange peel prepared in step S3, adjust the pH to 5.5, and continue to ferment for 50 min. After the staged fermentation is completed, heat it to 90 °C for inactivation treatment for 10 min, immediately cool it to 35 °C, and sieve it through a 120-mesh sieve to obtain the enzymolysis solution; S5: Add yeast, Monascus purpureus, yeast extract, potassium dihydrogen phosphate, and vitamin B into the enzymolysis solution prepared in step S4, control the temperature to 28°C, charge dissolved oxygen at 10 mg / L, conduct fermentation treatment for 24 h, then add Lactobacillus plantarum and corncob powder, raise the temperature to 37°C, and conduct fermentation treatment for 30 h under anaerobic conditions to obtain a fermentation broth; S6: Add β-cyclodextrin and arabic gum into the fermentation broth prepared in step S5, stir for 2 h, sieve through a 100-mesh sieve, then sieve through a 200-mesh sieve, conduct homogenization treatment once at 25 MPa, then conduct homogenization treatment once at 40 MPa, and then maintain at 72°C for 30 s for pasteurization treatment, and quickly cool to 25°C in an ice bath to obtain a corn juice composite beverage.

[0018] Comparative Example 1: The process operations of Comparative Example 1 and Example 2 are basically the same, the difference is that in Comparative Example 1, the raw materials orange peel and black rice are not added.

[0019] Comparative Example 2: The process operations of Comparative Example 2 and Example 2 are basically the same, the difference is that in Comparative Example 2, only α-amylase is used for enzymatic hydrolysis in the first stage, and pullulanase is removed.

[0020] Comparative Example 3: The process operations of Comparative Example 3 and Example 2 are basically the same, the difference is that in Comparative Example 3, all enzyme preparations (α-amylase, pullulanase, neutral protease, and tannase) are added synchronously at 55°C, and the enzymatic hydrolysis time is the same as that in Example 2.

[0021] Comparative Example 4: The process operations of Comparative Example 4 and Example 2 are basically the same, the difference is that in Comparative Example 4, Lactobacillus plantarum is removed.

[0022] Performance Test: Microbiological Test: Test the citrinin content of the corn juice composite beverage samples prepared in Examples 1 to 3 and Comparative Examples 1 to 4 according to GB 5009.222-2016; detect Escherichia coli according to GB 4789.38-2012; detect Salmonella according to GB 4789.4-2016; detect Staphylococcus aureus according to GB 4789.10-2016; the test results are shown in Table 1 below.

[0023] Table 1. Microbiological test results of corn juice composite beverage

[0024] As can be seen from the results in Table 1, no obvious pathogenic bacteria were detected in the corn juice composite beverage prepared by the present invention, which has excellent safety and meets the food safety standards.

[0025] Antioxidant test: Take 2 mL of DPPH solution and 2 mL of the sample solution to be tested (for the corn juice composite beverage prepared in Example 2 and Comparative Examples 1-4, take 1 mL and dissolve it in 5 mL of absolute ethanol). Mix well and place in the dark for 30 min. Using the absolute ethanol solution as a reference, measure the absorbance value at 517 nm. The DPPH solution is a solution with a concentration of 0.1 mM prepared with absolute ethanol as the solvent. Calculate the DPPH free radical scavenging rate (%) = [1 - (absorbance of the sample and DPPH mixture - absorbance of the sample solution without DPPH) / absorbance of the DPPH solution only] × 100%), and the results are as Figure 1 shown.

[0026] As can be Figure 1 seen from the results, the corn juice composite beverage prepared by the present invention exerts an excellent antioxidant effect through the synergistic action of multiple raw materials and multi-level processes; from the results of Comparative Example 1 and Example 2, it can be seen that orange peel is rich in flavonoids and limonene, and black rice contains anthocyanins. After removal, the main antioxidant substances in the beverage are only zeaxanthin in corn and β-carotene in carrots. The antioxidant network is broken, and the antioxidant effect is significantly reduced; from the results of Comparative Example 2 and Example 2, it can be seen that the lack of pullulanase leads to incomplete deconstruction of amylopectin, affecting the metabolism of Monascus purpureus. As a result, Monascus purpureus needs to secrete more amylase, extending the metabolic cycle, and may generate more secondary antioxidant products. Starch residues may inhibit the dissolution of polyphenols in orange peel / black rice, affecting the production of antioxidant products, and thus affecting the antioxidant effect; from the results of Comparative Example 3 and Example 2, it can be seen that neutral protease hydrolyzes corn protein prematurely, resulting in incomplete deconstruction of the starch network and insufficient reduction of sugars. The metabolism of Monascus purpureus and yeast turns to lipids or amino acids, reducing the production of antioxidant products. Moreover, the residual tannic acid chelates with metal ions, significantly reducing the DPPH free radical scavenging ability; from the results of Comparative Example 4 and Example 2, it can be seen that the lack of Lactobacillus plantarum leads to insufficient lactic acid production, resulting in an increase in pH. The degradation rate of black rice anthocyanins increases due to pH sensitivity; the activity of β-glucosidase decreases, and flavonoid glycosides in orange peel (such as hesperidin) cannot be converted into aglycones (such as hesperetin), thereby reducing the antioxidant activity.

[0027] Flavor test: Select 25 volunteers and randomly divide them into 5 groups with 5 people in each group. Give the corn juice composite beverage prepared in Example 2 and Comparative Examples 1-4 to each group for tasting. Each person scores the corn juice composite beverage prepared in Example 2 and Comparative Examples 1-4 respectively. Among them, Comparative Example 4 is only tasted. Score from three aspects: aroma (30% proportion), appearance (30% proportion), and taste (40% proportion). The score ranges from 1 to 10, with 10 being the best. The results are shown in Table 2 below.

[0028] Table 2. Flavor test results of corn juice composite beverage

[0029] As can be seen from the results in Table 2, the corn juice composite beverage prepared by the present invention has excellent flavor, appearance and taste; from the results of Comparative Example 1 and Example 2, it can be seen that there is only the cereal aroma of corn and carrot, lacking the fresh aroma of orange peel and the compound aroma of black rice. Maybe the sweetness is too high and the flavor is weak. Although more reducing sugars are retained, the short peptides are insufficient and the lubrication feeling is slightly weak. There is no orange peel tannic acid, but the incomplete hydrolysis of corn protein may lead to the residue of bitter peptides; in Comparative Example 2, tannic acid was not degraded in advance, and the residual tannic acid may inhibit the activity of neutral protease, resulting in an increase in the generation of bitter peptides; in Comparative Example 3, amylase and protease attacked the substrate simultaneously, and the macromolecular starch-protein complex hindered the enzyme-substrate binding efficiency. Tannase did not preferentially degrade tannic acid, and the residual tannic acid bound to neutral protease, reducing its activity. The dextrin produced by starch hydrolysis wrapped the protease, reducing the degree of protein hydrolysis, resulting in significant impacts on various aspects of the flavor; from the results of Comparative Example 4 and Example 2, the absence of Lactobacillus plantarum led to an increase in the pH of the product, accelerated degradation of anthocyanins, decreased color stability, and the flavor was affected to a certain extent.

[0030] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principle and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A corn juice compound beverage, characterized in that, It consists of the following raw materials by weight: 30 - 40 parts of corn, 5 - 8 parts of black rice, 4 - 7 parts of oats, 8 - 12 parts of carrots, 1 - 3 parts of corn cob powder, 0.5 - 1.5 parts of orange peel, 0.4 - 0.6 parts of composite enzyme species, 0.3 - 0.5 parts of β-cyclodextrin, 0.1 - 0.2 parts of arabic gum, 1 - 2 parts of inulin, 0.05 - 0.15 parts of yeast extract, 0.02 - 0.04 parts of potassium dihydrogen phosphate, 0.001 - 0.003 parts of vitamin B, and 0.25 - 0.4 parts of composite bacterial species.

2. The corn juice composite beverage according to claim 1, wherein The corn consists of 95% corn kernels and 5% corn silk.

3. A corn juice composite beverage according to claim 2, characterized in that, The composite enzyme species consists of the following components by weight: 0.15 - 0.25 parts of α-amylase, 0.07 - 0.12 parts of pullulanase, 0.03 - 0.05 parts of tannase, and 0.05 - 0.08 parts of neutral protease.

4. A corn juice compound beverage according to claim 3, characterized in that The composite bacterial species consists of the following components by weight: 0.07 - 0.1 parts of yeast, 0.15 - 0.25 parts of Lactobacillus plantarum, and 0.03 - 0.05 parts of Monascus purpureus.

5. A method for preparing the corn juice composite beverage according to any one of claims 1-4, characterized in that, The specific preparation steps are as follows: S1: After cleaning the corn, add it to water and boil it under normal pressure, then perform autoclaving treatment. After natural pressure reduction, maintain the treatment and cool it down to obtain pretreated corn and corn cooking water; S2: Soak the black rice in a citric acid solution, filter and drain it, then mix it with oatmeal, and then heat it up, grind, crush and screen to obtain pretreated black rice - oats; S3: Dice the carrots and mix them evenly with the corn cooking water prepared in step S1, perform high-temperature rotary baking treatment, filter and drain to obtain pretreated carrots; Air-dry the orange peel to obtain pretreated orange peel; S4: Add the pretreated corn prepared in step S1, the pretreated black rice - oats prepared in step S2, the pretreated carrots and pretreated orange peel prepared in step S3, α-amylase, pullulanase, neutral protease and tannase into a fermentation tank for staged fermentation. After the staged fermentation treatment is completed, heat up for inactivation treatment, immediately cool it, and screen through a sieve to obtain an enzymolysis solution; S5: Add yeast, Lactobacillus plantarum, corn cob powder, Monascus purpureus, yeast extract, potassium dihydrogen phosphate and vitamin B into the enzymolysis solution prepared in step S4 for staged fermentation to obtain a fermentation broth; S6: Add β-cyclodextrin and arabic gum into the fermentation broth prepared in step S5, stir, screen through a sieve, then screen through a finer sieve, perform homogenization treatment, sterilization treatment, and quickly cool in an ice bath to obtain a corn juice composite beverage.

6. A preparation method of the corn juice composite beverage according to claim 5, characterized in that, In step S4, the specific operation of the staged fermentation is as follows: Add the pretreated corn prepared in step S1, α-amylase, and pullulanase into the fermentation tank, adjust the pH to 5.8 - 6.2, ferment at 55 - 60 °C for 10 - 20 min, then add the pretreated black rice-oat prepared in step S2, and continue to ferment for 20 - 30 min; then add the carrots prepared in step S3, adjust the pH to 7, reduce the temperature to 45 - 50 °C at a rate of 0.5 °C / min, and ferment for 30 - 50 min; then add tannase and the pretreated orange peel prepared in step S3, adjust the pH to 5.5, and continue to ferment for 30 - 50 min.

7. A preparation method of the corn juice composite beverage according to claim 6, characterized in that, In step S5, the specific operation of the staged fermentation is as follows: Add yeast, Monascus purpureus, ammonium sulfate, potassium dihydrogen phosphate, and vitamin B into the enzymatic hydrolysate prepared in step S4, control the temperature at 28 °C, charge dissolved oxygen at 8 - 10 mg / L, ferment for 16 - 24 h, then add Lactobacillus plantarum and corncob powder, raise the temperature to 37 °C, and ferment under anaerobic conditions for 24 - 30 h.

8. A preparation method of the corn juice composite beverage according to claim 7, characterized in that, In step S6, the specific operation of the homogenization treatment is as follows: Homogenize once at 25 MPa and then homogenize once at 40 MPa.

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