Composite strain leavening agent and application of composite strain leavening agent in making of baked cakes

Abstract

The invention relates to a composite strain leavening agent and application thereof in baking cake making. The composite strain leavening agent is composed of six microorganisms according to a specific ratio, including saccharomyces cerevisiae, lactobacillus rolfsii, lactobacillus curvatus, lactobacillus plantarum, acetic acid bacteria and associated lactobacillus casei, the optimal volume ratio of fresh and wet thalli of all the strains is 1: 0.3: 0.2: 0.1: 0.2: 0.2, and the viable count of all the strains is larger than or equal to 1.0 * 10 < 7 > CFU / g. According to the composite strain leavening agent, through the synergistic effect of a specific flora combination, the dual technical effects are achieved in the baked cake making process, on one hand, metabolites of different strains act together, and the texture characteristics of dough are remarkably improved; and on the other hand, various flavor substances generated by the composite flora endow the baked cakes with unique flavor characteristics. The method is of great significance in realizing industrial production of traditional leavening agent fermented food, inheriting ethnic diet culture and promoting and developing ethnic spirit.

Description

Technical Field

[0001] The present invention relates to the technical field of microbial fermentation, and specifically provides a compound strain fermentation agent, a preparation method thereof, and an application in making baked cakes. Background Art

[0002] As an important carrier of Chinese food culture, traditional fermentation agents in China (such as yeast, old dough, old leaven, etc.) have a long historical inheritance and rich microbial diversity. The mixed fermentation system with multiple co-existing strains can produce a variety of flavor substances such as alcohols, esters, aldehydes, and phenols through complex biochemical reactions such as saccharification, fermentation, and esterification, endowing flour products with unique flavor characteristics and excellent texture properties, and being deeply loved by consumers. Baked cake is one of the traditional fermented flour products in China, with a history of inheritance of over a thousand years and occupies a very important position in people's daily diet. At present, the baked cake industry faces problems such as low industrialization level and insufficient product standardization. Most commercially available products adopt a small-scale on-site production and sales model, resulting in uneven quality. Commercial yeast has the advantage of high fermentation efficiency but a single flavor. Traditional fermentation agents can give better taste, flavor, and quality to pasta, but due to differences in different geographical and climatic conditions, there are problems such as unstable bacterial community structure and lack of standard production processes, which restrict industrial development. The international academic community has studied the fermentation system of sourdough for more than a hundred years and has established a complete theoretical system in aspects such as the composition of microbial flora, the metabolic mechanisms of dominant strains, and fermentation characteristics. In contrast, the systematic research on traditional fermentation agents in China is still in its infancy, and the existing work mainly focuses on basic aspects such as process optimization, isolation and screening of strains, and the influence of fermentation agents on the quality of baked cakes. By conducting scientific and systematic research on the microbial flora in traditional fermentation agents, their gas production, acid production capabilities, and the flavor substances generated by fermentation, so as to understand the flavor substances and their formation mechanisms in traditional fermentation agent-fermented foods, and then produce safe, healthy, and nutritious old dough fermented foods, which is of great significance for realizing the industrial production of traditional fermentation agent-fermented foods, inheriting national food culture, and carrying forward national spirit. In view of the current situation in the market where single-strain fermentation agents dominate and compound strain products are in short supply and cannot meet market demand, the present invention innovatively proposes a compound strain fermentation agent with a unique flavor for making baked cakes and a preparation method thereof, which is applied to the production of baked cakes, providing reference and significance for the analysis and application of compound strain fermentation, and further promoting the modern application process of traditional fermentation technology. Summary of the Invention

[0003] Technical Problem to be Solved: The technical problem to be solved by the present invention is to provide a compound strain fermentation agent and a preparation method thereof, which are applied to the production of baked cakes. The compound strain fermentation agent has the effect of improving the texture of the dough and makes the produced baked cakes have a unique flavor. To achieve the above technical objectives, the present invention is specifically realized through the following technical solutions.

[0004] Technical solution: A composite strain fermenting agent, comprising Saccharomyces cerevisiae, Lactobacillus furfuratus, Lactobacillus curvatus, Lactobacillus plantarum, Acetobacter and Lactobacillus crustorum. Preferably, the volume ratio of the fresh and wet bacterial bodies of Saccharomyces cerevisiae, Lactobacillus furfuratus, Lactobacillus curvatus, Lactobacillus plantarum, Acetobacter and Lactobacillus crustorum is 1:(0.1 - 0.3):(0.1 - 0.3):(0.1 - 0.3):(0.1 - 0.3):(0.1 - 0.3). Further, the volume ratio of the fresh and wet bacterial bodies of Saccharomyces cerevisiae, Lactobacillus furfuratus, Lactobacillus curvatus, Lactobacillus plantarum, Acetobacter and Lactobacillus crustorum is 1:0.3:0.2:0.1:0.2:0.2. Preferably, the viable count of Saccharomyces cerevisiae ≥ 1.0×10 7 CFU / g. Preferably, the viable count of Lactobacillus furfuratus ≥ 1.0×10 7 CFU / g. Preferably, the viable count of Lactobacillus curvatus ≥ 1.0×10 7 CFU / g. Preferably, the viable count of Lactobacillus plantarum ≥ 1.0×10 7 CFU / g. Preferably, the viable count of Acetobacter ≥ 1.0×10 7 CFU / g. Further, the viable counts of Saccharomyces cerevisiae, Lactobacillus furfuratus, Lactobacillus curvatus, Lactobacillus plantarum, Acetobacter and Lactobacillus crustorum are (1.0 - 5.0)×10 7 CFU / g. Preferably, the preparation method of the fresh and wet bacterial body of Saccharomyces cerevisiae is as follows: Streak Saccharomyces cerevisiae on WL nutrient agar medium and culture it at 26 - 30°C for 2 - 3 d; then pick single colonies on the plate and inoculate them into YPD liquid medium, and shake them on a shaker at 26 - 30°C for 18 - 22 h to obtain the fresh and wet bacterial body of Saccharomyces cerevisiae. Preferably, the preparation method of the fresh and wet bacterial bodies of Lactobacillus furfuratus, Lactobacillus curvatus, Lactobacillus plantarum and Lactobacillus crustorum is as follows: Streak Lactobacillus furfuratus, Lactobacillus curvatus, Lactobacillus plantarum and Lactobacillus crustorum on MRS solid medium and culture them at 34 - 38°C for 2 - 3 d; then pick single colonies on each plate and inoculate them into MRS liquid medium, and shake them on a shaker at 34 - 38°C for 18 - 22 h to obtain the fresh and wet bacterial bodies of Lactobacillus furfuratus, Lactobacillus curvatus, Lactobacillus plantarum and Lactobacillus crustorum. Preferably, the method for preparing the fresh and wet cells of the acetic acid bacteria is as follows: streak the acetic acid bacteria on a GYC solid medium and culture at 28 - 34 °C for 2 - 3 d; then pick single colonies on the plate and inoculate them into a GYC liquid medium, and shake at 28 - 34 °C for 18 - 22 h to obtain the fresh and wet cells of the acetic acid bacteria. Preferably, the method for making the baked cake includes the following steps: add 92 g of distilled water to 200 g of wheat flour, and then add the Saccharomyces cerevisiae, Lactobacillus rhamnosus furanicus, Lactobacillus curvatus, Lactobacillus plantarum, acetic acid bacteria and Lactobacillus crustorum as claimed in claim 1 and mix evenly, and place the dough in a constant temperature incubator for fermentation. Preferably, the fermentation conditions include: fermentation temperature of 28 - 32 °C, fermentation humidity of 75% - 90%, and fermentation time of 5 - 8 h. Beneficial effects Compared with the prior art, the present invention has the following advantages and positive effects: The compound starter prepared by the present invention scientifically compound six selected functional strains, which are Saccharomyces cerevisiae, Lactobacillus rhamnosus furanicus, Lactobacillus curvatus, Lactobacillus plantarum, acetic acid bacteria and Lactobacillus crustorum. 1. Gas production and efficiency improvement: During the fermentation process, Saccharomyces cerevisiae can rapidly decompose glucose to generate CO2. However, relying solely on Saccharomyces cerevisiae, a lag phenomenon is likely to occur in the later stage of fermentation. Lactobacillus rhamnosus furanicus and Lactobacillus curvatus generate additional CO2 through heterofermentation pathways using specific sugar substrates, further enhancing the gas production efficiency. The generated CO2 is intercepted by the gluten in the dough in a network structure. As the CO2 accumulates continuously, fine pores gradually form inside the dough, causing the dough to quickly puff up and forming a porous texture after baking. This "dual-path gas production" mode effectively overcomes the shortcoming of single-strain fermentation in gas production sustainability and provides a solid guarantee for the gas production requirements of the product. 2. Flavor synergy: During the fermentation process, acetic acid bacteria metabolize to produce acetic acid, giving the baked cake a fresh sour aroma; Lactobacillus plantarum metabolizes to generate lactic acid, increasing the mellow feeling of the baked cake flavor; Lactobacillus crustorum generates trace amounts of esters (such as fruit esters), adding a unique fruity flavor to the baked cake. A variety of flavor substances are intertwined and synergistically act, making the aroma of the baked cake rich and hierarchical, greatly enhancing the flavor dimension and tasting value of the baked cake. 3. Texture optimization: The exopolysaccharides produced by Lactobacillus rogosae, Lactobacillus curvatus, and Lactobacillus plantarum can significantly improve the gluten network structure, making it more uniform and fine, thereby enhancing the softness and volume of bread. During baking, this stable pore structure serves as a support, effectively preventing collapse caused by gas escape or unstable structure, thus ensuring that the baked scone forms a porous, plump, and fluffy appearance and excellent texture after baking. In addition, exopolysaccharides can also protect the gluten network structure by reducing ice crystal formation, further improving the quality of frozen dough. By virtue of the perfect integration of the three major advantages of efficient gas production, flavor synergy, and texture optimization, the composite strain starter of the present invention completely breaks through the limitations of traditional fermentation processes, successfully creating high-quality scones with more excellent fluffiness, rich and mellow aroma, and diverse taste, bringing new technological breakthroughs and product upgrade directions to the scone industry. Detailed implementation methods To further understand the present invention, the preferred implementation schemes of the present invention will be described below in conjunction with examples. The specific preferred examples are as follows: Example 1 This example is for the preparation of scones with a volume ratio of Saccharomyces cerevisiae, Lactobacillus rogosae, Lactobacillus curvatus, Lactobacillus plantarum, Acetobacter, and Lactobacillus crustorum in the composite strain starter of 1:0.1:0.3:0.3:0.2:0.1, and includes the following steps: S1. Isolate the colonies of Saccharomyces cerevisiae, Lactobacillus rogosae, Lactobacillus curvatus, Lactobacillus plantarum, Acetobacter, and Lactobacillus crustorum: Take 10 g of traditional starter sample in 90 mL of sterile physiological saline and homogenize for 30 min. Select 10 -3 -10 -6 Gradient dilutions are respectively spread and cultured on WL nutrient agar medium, MRS solid medium, and GYC solid medium for 2 - 3 d, and then the colonies of Saccharomyces cerevisiae, Lactobacillus rogosae, Lactobacillus curvatus, Lactobacillus plantarum, Acetobacter, and Lactobacillus crustorum are picked; S2. Prepare the fresh and wet cells of Saccharomyces cerevisiae: Inoculate Saccharomyces cerevisiae on WL nutrient agar medium by streaking, culture at 28 °C for 2 - 3 d, then pick single colonies on the plate into YPD liquid medium, and shake at 28 °C for 20 h to obtain the fresh and wet cells of Saccharomyces cerevisiae; S3. Prepare the fresh and wet cells of Lactobacillus rogosae: Inoculate Lactobacillus rogosae on MRS solid medium by streaking, culture at 36 °C for 2 - 3 d, then pick single colonies on the plate into MRS liquid medium, and shake at 36 °C for 20 h to obtain the fresh and wet cells of Lactobacillus rogosae; S4. Preparation of fresh and wet cells of Lactobacillus curvatus: Streak Lactobacillus curvatus on MRS solid medium, and after culturing at 36 °C for 2 - 3 days, pick single colonies on the plate and inoculate them into MRS liquid medium, and shake at 36 °C for 20 h to obtain fresh and wet cells of Lactobacillus curvatus; S5. Preparation of fresh and wet cells of Lactobacillus plantarum: Streak Lactobacillus plantarum on MRS solid medium, and after culturing at 36 °C for 2 - 3 days, pick single colonies on the plate and inoculate them into MRS liquid medium, and shake at 36 °C for 20 h to obtain fresh and wet cells of Lactobacillus plantarum; S6. Preparation of fresh and wet cells of Lactobacillus crustorum: Streak Lactobacillus crustorum on MRS solid medium, and after culturing at 36 °C for 2 - 3 days, pick single colonies on the plate and inoculate them into MRS liquid medium, and shake at 36 °C for 20 h to obtain fresh and wet cells of Lactobacillus crustorum; S7. Preparation of fresh and wet cells of Lactobacillus crustorum: Streak Acetobacter on GYC solid medium, and after culturing at 30 °C for 2 - 3 days, pick single colonies on the plate and inoculate them into GYC liquid medium, and shake at 30 °C for 20 h to obtain fresh and wet cells of Lactobacillus crustorum; S8. Preparation of fermented dough: Add 92 g of distilled water to 200 g of wheat flour, then add Saccharomyces cerevisiae, Lactobacillus rogosae, Lactobacillus curvatus, Lactobacillus plantarum, Acetobacter and Lactobacillus crustorum and mix evenly to form dough. The volume ratio of each bacterium is 1:0.1:0.3:0.3:0.2:0.1, and the viable count of each strain is 1.0×10 7 CFU / g; Place the dough in an incubator at a temperature of 30 °C and a humidity of 85% and ferment for 6 h to obtain fermented dough; S9. Preparation of cake blanks and secondary fermentation: Re - add alkali and knead the dough. After repeatedly pressing to exhaust the air, divide the dough into 100 - g portions. Use a round cake press to make the dough into round cake blanks with a diameter of 10 cm and a thickness of 10 mm, and then place them in a proofing box at a temperature of 30 °C and a humidity of 85% for secondary fermentation for 40 min; S10. Baking: Place the cake blanks in an oven with a surface fire temperature of 180 °C and a bottom fire temperature of 200 °C and bake for 16 h. After baking, take out the baked cakes and let them cool naturally at room temperature for 30 min for standby. Example 2 The difference between Example 2 and Example 1 is that the volume ratio of Saccharomyces cerevisiae, Lactobacillus rogosae, Lactobacillus curvatus, Lactobacillus plantarum, Acetobacter and Lactobacillus crustorum in the compound strain starter is different. In this example, the volume ratio of Saccharomyces cerevisiae, Lactobacillus rogosae, Lactobacillus curvatus, Lactobacillus plantarum, Acetobacter and Lactobacillus crustorum in the compound strain starter is 1:0.2:0.1:0.3:0.2:0.2. Example 3 Example 3 is different from Example 1 in that the volume ratios of Saccharomyces cerevisiae, Lactobacillus furfuratus, Lactobacillus curvatus, Lactobacillus plantarum, Acetobacter, and Lactobacillus crustorum in the compound strain fermenting agent are different. In this example, the volume ratios of Saccharomyces cerevisiae, Lactobacillus furfuratus, Lactobacillus curvatus, Lactobacillus plantarum, Acetobacter, and Lactobacillus crustorum in the compound strain fermenting agent are 1:0.3:0.3:0.2:0.1:0.1. Example 4 Example 4 is different from Example 1 in that the volume ratios of Saccharomyces cerevisiae, Lactobacillus furfuratus, Lactobacillus curvatus, Lactobacillus plantarum, Acetobacter, and Lactobacillus crustorum in the compound strain fermenting agent are different. In this example, the volume ratios of Saccharomyces cerevisiae, Lactobacillus furfuratus, Lactobacillus curvatus, Lactobacillus plantarum, Acetobacter, and Lactobacillus crustorum in the compound strain fermenting agent are 1:0.3:0.2:0.1:0.2:0.2. The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention. To further illustrate the technical effects of the present invention, the present invention also sets up comparative examples, which are specifically as follows: Comparative Example 1 Comparative Example 1 is for the preparation of scones with a compound strain fermenting agent without adding Saccharomyces cerevisiae. Specifically, the volume ratios of Lactobacillus furfuratus, Lactobacillus curvatus, Lactobacillus plantarum, Acetobacter, and Lactobacillus crustorum in the compound strain fermenting agent are 0.3:0.2:0.1:0.2:0.2. Prepare a compound strain fermenting agent without adding Saccharomyces cerevisiae according to the steps described in Example 4. Comparative Example 2 Comparative Example 2 is for the preparation of scones with a compound strain fermenting agent without adding Lactobacillus furfuratus. Specifically, the volume ratios of Saccharomyces cerevisiae, Lactobacillus curvatus, Lactobacillus plantarum, Acetobacter, and Lactobacillus crustorum in the compound strain fermenting agent are 1:0.2:0.1:0.2:0.2. Prepare a compound strain fermenting agent without adding Lactobacillus furfuratus according to the steps described in Example 4. Comparative Example 3 Comparative Example 3 is for the preparation of scones with a compound strain fermenting agent without adding Lactobacillus curvatus. Specifically, the volume ratios of Saccharomyces cerevisiae, Lactobacillus furfuratus, Lactobacillus plantarum, Acetobacter, and Lactobacillus crustorum in the compound strain fermenting agent are 1:0.3:0.1:0.2:0.2. Prepare a compound strain fermenting agent without adding Lactobacillus curvatus according to the steps described in Example 4. Comparative Example 4 Comparative Example 4 was the preparation of scones with a compound starter without Lactobacillus plantarum. Specifically, the volume ratio of Saccharomyces cerevisiae, Lactobacillus furfuratus, Lactobacillus curvatus, Acetobacter, and Lactobacillus parafarraginis in the compound starter was 1:0.3:0.2:0.2:0.2. The compound starter without Lactobacillus plantarum was prepared according to the steps described in Example 4. Comparative Example 5 Comparative Example 5 was the preparation of scones with a compound starter without Lactobacillus parafarraginis. Specifically, the volume ratio of Saccharomyces cerevisiae, Lactobacillus furfuratus, Lactobacillus curvatus, Lactobacillus plantarum, and Acetobacter in the compound starter was 1:0.3:0.2:0.1:0.2. The compound starter without Lactobacillus parafarraginis was prepared according to the steps described in Example 4. Comparative Example 6 Comparative Example 5 was the preparation of scones with a compound starter without Acetobacter. Specifically, the volume ratio of Saccharomyces cerevisiae, Lactobacillus furfuratus, Lactobacillus curvatus, Lactobacillus plantarum, and Lactobacillus parafarraginis in the compound starter was 1:0.3:0.2:0.1:0.2. The compound starter without Acetobacter was prepared according to the steps described in Example 4. Comparative Example 7 Comparative Example 7 was the preparation of scones fermented with commercial yeast. The scones fermented with commercial yeast were prepared according to the steps described in Example 4, and the addition amount of the commercial high-activity yeast dry powder was 0.2 g. Table 1 Sensory scoring criteria for scones Table 2 Sensory scoring records of scones prepared in Examples 1 - 4 and Comparative Examples 1 - 7 Note: Different lowercase letters in the same column indicate significant differences between different samples (P < 0.05). Table 3 Texture properties of scones prepared in Examples 1 - 4 and Comparative Examples 1 - 7 Sample Hardness Elasticity Cohesiveness Chewiness Resilience Example 1 <![CDATA[2881.11±141.42 bc > <![CDATA[0.92±0.01 b > <![CDATA[0.86±0.02 b > <![CDATA[2462.91±55.03 bc > <![CDATA[0.51±0.01 a > Example 2 <![CDATA[2913.29±129.53 bc > <![CDATA[0.93±0.02 b > <![CDATA[0.87±0.01 b > <![CDATA[2432.32±103.67 bc > <![CDATA[0.52±0.01 a > Example 3 <![CDATA[2908.31±98.99 bc > <![CDATA[0.93±0.02 b > <![CDATA[0.88±0.02 b > <![CDATA[2435.±127.35 bc > <![CDATA[0.53±0.01 a > Example 4 <![CDATA[2805.11±121.38 c > <![CDATA[0.93±0.03 b > <![CDATA[0.88±0.01 b > <![CDATA[2379.47±75.33 bc > <![CDATA[0.52±0.01 a > Comparative Example 1 <![CDATA[11429.38±187.28 a > <![CDATA[0.71±0.05 a > <![CDATA[0.91±0.03 a > <![CDATA[9942.81±187.67 a > <![CDATA[0.42±0.01 b > Comparative Example 2 <![CDATA[2909.52±62.95 bc > <![CDATA[0.92±0.01 b > <![CDATA[0.87±0.02 b > <![CDATA[2481.65±110.27 bc > <![CDATA[0.52±0.01 a > Comparative Example 3 <![CDATA[2887.67±79.74 bc > <![CDATA[0.92±0.01 b > <![CDATA[0.88±0.01 b > <![CDATA[2496.92±71.60 bc > <![CDATA[0.52±0.01 a > Comparative Example 4 <![CDATA[2967.53±48.75 bc > <![CDATA[0.92±0.01 b > <![CDATA[0.86±0.02 b > <![CDATA[2487.64±93.97 bc > <![CDATA[0.52±0.01 a > Comparative Example 5 <![CDATA[3098.56±83.48 b > <![CDATA[0.92±0.01 b > <![CDATA[0.86±0.02 b > <![CDATA[2548.88±81.84 b > <![CDATA[0.51±0.01 a > Comparative Example 6 <![CDATA[3024.45±120.21 b > <![CDATA[0.93±0.03 b > <![CDATA[0.86±0.02 b > <![CDATA[2597.53±97.02 b > <![CDATA[0.51±0.01 a > Comparative Example 7 <![CDATA[3118.19±96.84 b > <![CDATA[0.93±0.03 b > <![CDATA[0.87±0.01 b > <![CDATA[2607.66±49.91 b > <![CDATA[0.53±0.01 a > Note: Different lowercase letters in the same column indicate significant differences between different samples (P < 0.05). A sensory evaluation panel consisting of 10 food professionals conducted a sensory evaluation and scoring of the scones prepared in Examples 1 - 4 and Comparative Examples 1 - 7 from 7 dimensions: specific volume, surface color, surface morphology, internal structure, viscoelasticity, taste, and smell. As can be seen from Table 2, there are significant differences in the scores of each sensory item of the scones prepared in Example 4 and Comparative Example 1. When comparing Example 4 with Comparative Examples 2 - 7, there are no significant differences in the scores of specific volume, internal structure, and viscoelasticity of the scones, but there are significant differences in the scores of surface morphology, surface color, taste, and smell of the scones. The surface color of the scones prepared in Example 4 is golden yellow, the color is more uniform, the surface morphology is more complete, the taste is softer, the taste is sweet, and there is an obvious fermentation fragrance. Its total sensory score is the highest, which is 84.9 points. The texture characteristics of the scones prepared in Examples 1 - 4 and Comparative Examples 1 - 7 were analyzed, and 5 indexes including hardness, elasticity, cohesiveness, chewiness, and resilience were measured. As can be seen from Table 3, there are significant differences in hardness, elasticity, cohesiveness, chewiness, and resilience of the scones prepared in Example 4 and Comparative Example 1. There are no significant differences in elasticity, cohesiveness, and resilience of the scones prepared in Example 4 and Comparative Examples 2 - 7, but there are significant differences in hardness and chewiness. The hardness of the scones prepared in Example 4 is the smallest and the chewiness is better. Based on the above results, the quality, flavor, and texture characteristics of the scones prepared by the preparation method described in Example 4 are the best. The volume ratio of Saccharomyces cerevisiae, Lactobacillus rhamnosus furanicus, Lactobacillus curvatus, Lactobacillus plantarum, Acetobacter, and Lactobacillus crustorum in the compound strain starter is 1:0.3:0.2:0.1:0.2:0.2. The compound fermentation agent prepared in this proportion has the best improvement effect on the quality, flavor, and texture characteristics of the scones. The present invention provides an important theoretical basis and technical support for the optimization design and industrial application of the compound strain fermentation system. Through the strain co-fermentation mechanism, the quality of the scone product is improved, providing a new technical path and industrial transformation direction for the modernization upgrade of traditional flour-made foods.

Claims

1. A compound strain fermenting agent, characterized in that, It includes Saccharomyces cerevisiae, Lactobacillus rhamnosus furanicus, Lactobacillus curvatus, Lactobacillus plantarum, Acetobacter and Lactobacillus crustorum; the volume ratio of the fresh and wet cells of Saccharomyces cerevisiae, Lactobacillus rhamnosus furanicus, Lactobacillus curvatus, Lactobacillus plantarum, Acetobacter and Lactobacillus crustorum is 1:(0.1 - 0.3):(0.1 - 0.3):(0.1 - 0.3):(0.1 - 0.3):(0.1 - 0.3).

2. The compound strain fermenting agent according to claim 1, wherein, The volume ratio of the fresh and wet cells of Saccharomyces cerevisiae, Lactobacillus rhamnosus furanicus, Lactobacillus curvatus, Lactobacillus plantarum, Acetobacter and Lactobacillus crustorum is 1:0.3:0.2:0.1:0.2:0.

2.

3. A composite strain fermenter according to claim 1, characterized in that, The viable counts of the Saccharomyces cerevisiae, Lactobacillus rhamnosus furfurylis, Lactobacillus curvatus, Lactobacillus plantarum, Acetobacter and Lactobacillus crustorum are ≥ 1.0×10 7 CFU / g.

4. The composite strain fermenting agent according to claim 3, characterized in that The viable counts of the Saccharomyces cerevisiae, Lactobacillus rogosae, Lactobacillus curvatus, Lactobacillus plantarum, Acetobacter and Lactobacillus crustorum are (1.0 - 5.0)×10 7 CFU / g.

5. A composite strain fermenting agent according to claim 1, characterized in that The preparation method of the fresh and wet cells of Saccharomyces cerevisiae is as follows: streak Saccharomyces cerevisiae on WL nutrient agar medium and culture at 26 - 30 °C for 2 - 3 d; then pick single colonies on the plate and inoculate them into YPD liquid medium, and shake them on a shaker at 26 - 30 °C for 18 - 22 h to obtain the fresh and wet cells of Saccharomyces cerevisiae.

6. The compound strain fermenting agent according to claim 1, wherein The preparation method of the fresh and wet cells of Lactobacillus rhamnosus furanicus, Lactobacillus curvatus, Lactobacillus plantarum and Lactobacillus crustorum is as follows: streak Lactobacillus rhamnosus furanicus, Lactobacillus curvatus, Lactobacillus plantarum and Lactobacillus crustorum on MRS solid medium and culture at 34 - 38 °C for 2 - 3 d; then pick single colonies on each plate and inoculate them into MRS liquid medium, and shake them on a shaker at 34 - 38 °C for 18 - 22 h to obtain the fresh and wet cells of Lactobacillus rhamnosus furanicus, Lactobacillus curvatus, Lactobacillus plantarum and Lactobacillus crustorum.

7. A composite strain fermenting agent according to claim 1, characterized in that, The preparation method of the fresh and wet cells of Acetobacter is as follows: streak Acetobacter on GYC solid medium and culture at 28 - 34 °C for 2 - 3 d; then pick single colonies on the plate and inoculate them into GYC liquid medium, and shake them on a shaker at 28 - 34 °C for 18 - 22 h to obtain the fresh and wet cells of Acetobacter.

8. Application of a composite strain fermenting agent according to any one of claims 1 - 7 in the production of scones.

9. The application according to claim 8, wherein The method for producing scones includes the following steps: add 92 g of distilled water to 200 g of wheat flour, then add the Saccharomyces cerevisiae, Lactobacillus rhamnosus furanicus, Lactobacillus curvatus, Lactobacillus plantarum, Acetobacter and Lactobacillus crustorum according to claim 1 and mix them evenly, and place the dough in a constant temperature incubator for fermentation.

10. The fermentation conditions according to claim 9 include: The fermentation temperature is 28 - 32 °C, the fermentation humidity is 75% - 90%, and the fermentation time is 5 - 8 h.

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