CN113755399B - A strain screening method and its application with the functional characteristics of producing aroma and suppressing mutton - Google Patents

Abstract

The invention discloses a strain screening method with the function of inhibiting the smell of mutton and application thereof. The strain screening method comprises the following steps: activating a bacterial sample, enriching and culturing, separating pure seeds, preparing fermented milk and measuring the aroma production performance; the screening basis comprises the following aspects: taking the identification results of artificial sensory and key aroma compounds as indexes, and analyzing the compounds with fruity, nutty, milk aroma and other aroma notes by GC-MS to be 2-heptanone, benzaldehyde, ethyl butyrate, ethyl caproate, isoamylol and the like; fatty acid compounds such as caprylic acid and caproic acid have characteristic smell of mutton smell; the invention screens out strains with the characteristic of producing fragrance and inhibiting the smell of mutton by utilizing the strain screening method, wherein the strains comprise lactococcus lactis SD-3, pediococcus acidilactici DN-1 and lactobacillus plantarum GM-6.

Description

A strain screening method and its application with the functional characteristics of producing aroma and suppressing mutton

technical field

The invention relates to a strain screening method with the functional characteristics of producing aroma and suppressing mutton and an application thereof, belonging to the technical field of microbes.

Background technique

Goat milk has high nutritional value and is rich in vitamins, mineral elements and active substances. Its protein and amino acid content are generally higher than cow's milk. In addition, its lactose content is low and easy to absorb. It is a good nutritional product for modern human health and is known as the "king of milk". However, the flavor of goat milk and its dairy products is relatively unique, and the corresponding products often have the problem of excessive smell, which further reduces the acceptance of consumers and restricts the further development of the goat milk industry.

In order to improve and enhance the flavor quality of goat dairy products, at present, exogenous addition and endogenous aroma enhancement are mainly used to regulate. However, compared with exogenous aroma enhancement methods such as conventional chemical aroma enhancement and flavoring agents, endogenous aroma enhancement through microbial fermentation is safer and healthier, and is not limited by raw materials.

Aroma-producing microorganisms refer to microorganisms that can ferment and metabolize aroma substances during the growth process. Most of them are lactic acid bacteria, bifidobacteria, yeasts and molds. Different aroma-producing microorganisms produce different aroma substances. Through the identification of the characteristic flavor and aroma quality research of the traditional sourdough cheese goat milk cake, we found that the milk flavor and fruity flavor attributes are easy to be accepted by consumers, while the smell of mutton and excessive sourness are not easy to accept. At the same time, methyl ketone substances such as 2-heptanone and 2-nonanone with milk flavor, benzaldehyde with nut and almond flavor, and ethyl butyrate with fruity flavor can inhibit the smell of mutton.

Therefore, for the fermentation strains, the screening of flavor-enhancing (increasing flavor substances such as milky and fruity flavors) and mutton-inhibiting (decreasing fatty acid content such as caproic acid and octanoic acid) strains can be used to improve and enhance the flavor of goat dairy products quality.

Contents of the invention

The technical problem to be solved by the present invention is to provide a strain screening method with the functional characteristics of producing aroma and suppressing mutton, aiming at the problem of heavy mutton smell of goat dairy products under traditional technology.

In order to solve the above problems, the invention provides a strain screening method with the functional characteristics of producing aroma and suppressing mutton, comprising the following steps:

Step 1: In a sterile environment, take samples from multiple fresh milk cakes and put them into sterile test tubes, add sterile water to fully shake and dissolve them evenly to obtain a bacterial suspension, and dilute the bacterial suspension with sterile water to form Bacterial liquids of different concentrations were spread on MRS agar medium in turn and cultivated at constant temperature. After the colonies grew, single colonies were picked, streaked, purified and cultivated to obtain a single strain;

Step 2: Inoculate the above-mentioned single strains obtained in the MRS liquid medium, and carry out constant temperature fermentation to obtain the fermentation liquid of the single strains;

Step 3: Centrifuge the fermented broth obtained above, and wash the precipitates obtained by the centrifugation with sterile water for several times, and then add sterile water equal to the volume of the bacterial suspension in step 1 to the cleaned precipitates, Vortex to obtain the fermentation broth;

Step 4: Inoculate the fermentation culture solution obtained in Step 3 into sterile goat milk, carry out fermentation culture at 37°C until the fermentation is completed at pH=4.6, and then naturally cool to room temperature to obtain the fermented milk to be tested;

Step 5: Take the fermented milk samples to be tested and carry out sensory evaluation primary screening and GC-MS aroma determination respectively, and after strain identification, obtain the strains with the functional characteristics of aroma production and suppression of mutton.

Preferably, the components of the MRS agar medium in step 1 include: peptone 10.0g/L, beef extract powder 8.0g/L, yeast extract powder 4.0g/L, glucose 20.0g/L, dipotassium hydrogen phosphate 2.0 g/L, diammonium hydrogen citrate 2.0g/L, sodium acetate 5.0g/L, magnesium sulfate 0.2g/L, manganese sulfate 0.04g/L, agar 14.0g/L and Tween 801.0g/L; The components of the MRS liquid medium in step 2 include: peptone 10.0g/L, beef extract powder 10.0g/L, yeast extract powder 5.0g/L, glucose 20.0g/L, magnesium sulfate 0.1g/L, sodium acetate 5.0 g/L, dipotassium hydrogen phosphate 2.0g/L, ammonium citrate 2.0g/L, manganese sulfate 0.05g/L and Tween 801.0g/L.

Preferably, the concentration of the bacterial suspension in the step 1 is 0.1 g/mL; the different concentrations of the bacterial liquid include concentrations of 10 ^-2 , 10 ^-3 , 10 ^-4 , 10 ^-5 and 10 ^-6 of bacteria liquid.

Preferably, the conditions for culturing at constant temperature in step 1 are: temperature 37°C, time 12h; the conditions for constant temperature fermentation in step 2 are: temperature 37°C, time 12h.

Preferably, the centrifugation conditions in step 3 are: temperature 4°C, rotation speed 6000 rpm, time 15 min; the shaking conditions are: rotation speed 6000 rpm, time 10 min.

Preferably, the volume ratio of the fermentation broth to the aseptic goat milk in step 4 is 5%.

Preferably, the sensory evaluation in step 5 includes aroma acceptance and aroma intensity evaluation indicators; the GC-MS aroma measurement includes: using headspace solid-phase microextraction to extract the flavor substances in the fermented milk to be tested, using GC-MS MS analyzes and identifies the flavor substances, and analyzes the generation and content changes of key aroma components.

Preferably, the key aroma components include 2-heptanone, benzaldehyde, caproic acid and octanoic acid.

The present invention also provides a bacterial strain with the functional characteristics of aroma production and suppression of mutton, which is obtained by screening the above-mentioned strains with the functional characteristics of aroma production and suppression of mutton, including Lactococcus lactis SD-3, Pediococcus lactis DN- 1 and Lactobacillus plantarum GM-6;

The preservation number of the Lactococcus lactis SD-3 is CCTCC M 2021743, and the Latin name is Lactococcuslactis SD-3. The preservation unit is the China Typical Culture Collection Center, and the preservation time is June 23, 2021. The preservation address is Wuhan, Hubei Province Preservation Center of Wuhan University, Luojia Mountain, Wuchang City;

The preservation number of the Pediococcus lactis DN-1 is CCTCC M 2021794, the Latin name is Pediococcuslactis DN-1, the preservation unit is the China Center for Typical Culture Collection, the preservation time is June 28, 2021, and the preservation address is Wuhan, Hubei Province Preservation Center of Wuhan University, Luojia Mountain, Wuchang City;

The preservation number of the Lactobacillus plantarum GM-6 is CCTCC M 2021744, and the Latin name is Lactobacillusplantarum GM-6. The preservation unit is the China Typical Culture Collection Center, and the preservation time is June 23, 2021. The preservation address is Wuhan, Hubei Province Preservation Center of Wuhan University, Luojia Mountain, Wuchang City.

The present invention also provides the application of the above-mentioned strains with the functional characteristics of producing aroma and suppressing mutton in fermenting goat milk.

GC-MS aroma measurement showed that the content of 2-heptanone, benzaldehyde and ester compounds in the fermented milk sample prepared by Lactococcus lactis lactic acid SD-3 was relatively high, the sensory evaluation results were the best, and the overall acceptance and aroma acceptance The sensory scores are all the highest, among which the milk flavor is the richest, and the types and total amount of aroma compounds are more abundant;

GC-MS aroma measurement shows that the fermented milk sample prepared by the Pediococcus lactis DN-1 contains a large amount of key aroma compounds such as 2-heptanone and isoamyl alcohol, and the content of fatty acid compounds such as butyric acid, caproic acid and octanoic acid is relatively low ;

GC-MS aroma measurement showed that the fermented milk sample prepared by Lactobacillus plantarum GM-6 had higher aroma acceptance, higher content of aldehyde compounds, and obvious nutty flavor.

Compared with prior art, the beneficial effect of the present invention is:

1. A strain screening method with the functional characteristics of producing aroma and suppressing mutton of the present invention, the strain obtained by screening can ensure that the fermentation sample can endogenously produce more milk-flavored and fruity-flavored substances that have an inhibitory effect on mutton odor, And to a certain extent, it reduces the production of mutton-flavored fatty acid components, optimizes the flavor quality of fermented milk products on the basis of not needing to add aroma substances from external sources, and reduces the production cost of fermented milk products;

2. The three strains screened by the screening method of the present invention have the bacterial classification Lactococcus lactis (Lactococcus lactis) SD-3, Pediococcus lactis (Pediococcus lactis) DN-1 and Lactobacillus plantarum (Lactobacillus plantarum) with the functional characteristics of producing fragrance and suppressing mutton. ) GM-6 fermented goat milk, the content of 3-hydroxy-2-butanone, 2-heptanone, 2-octanone and 2-nonanone is relatively high. The above ketone aroma substances have the characteristics of cream, cheese, coconut It also contains high content of almond-flavored benzaldehyde and fruity-flavored isoamyl alcohol, which are used in the identification of the characteristic flavor of sourdough cheese goat milk cake as a depressant. , positively affecting aroma components; at the same time, by analyzing the aroma components of samples fermented by different strains, it can also be seen that the fatty acids with a strong smell produced by the samples fermented by SD-3, DN-1 and GM-6 , compared with the fermented milk sample prepared by commercial bacterial powder YF-L811 in the comparative example, its content is also lower. That is to say, from the perspective of the production of aroma substances, the three strains of lactic acid bacteria have obvious characteristics of producing aroma and suppressing mutton when they are applied to ferment goat milk;

3. The goat milk fermented by Lactococcus lactis lactic acid SD-3, Pediococcus lactis DN-1 and Lactobacillus plantarum GM-6 screened by the present invention has the characteristics of color, texture, taste acceptance, aroma acceptance and overall acceptance, etc. The evaluation indicators of sensory acceptance were higher than those of fermented milk samples prepared from commercial bacterial powder YF-L811.

Description of drawings

Figure 1 is a sensory evaluation radar chart of fermented goat milk in Examples 2, 3, 4 and a comparative example.

Preservation instructions

The preservation number of Lactococcus lactis SD-3 is CCTCC M 2021743, and the Latin name is Lactococcus lactisSD-3. The preservation unit is the China Center for Typical Culture Collection, and the preservation time is June 23, 2021. The preservation address is Wuchang, Wuhan City, Hubei Province Luojia Mountain Preservation Center of Wuhan University;

The preservation number of Pediococcus lactis DN-1 is CCTCC M 2021794, and the Latin name is Pediococcus lactisDN-1. The preservation unit is the China Center for Type Culture Collection, and the preservation time is June 28, 2021. The preservation address is Wuchang, Wuhan City, Hubei Province Luojia Mountain Preservation Center of Wuhan University;

The preservation number of Lactobacillus plantarum GM-6 is CCTCC M 2021744, and the Latin name is Lactobacillusplantarum GM-6. The preservation unit is the China Center for Typical Culture Collection. The preservation time is June 23, 2021. The preservation address is Wuchang, Wuhan City, Hubei Province Luojia Mountain Collection Center of Wuhan University.

detailed description

In order to make the present invention more comprehensible, preferred embodiments are described in detail below with accompanying drawings.

The components of the MRS agar medium used in each embodiment of the present invention include: peptone 10.0g/L, beef extract powder 8.0g/L, yeast extract powder 4.0g/L, glucose 20.0g/L, dipotassium hydrogen phosphate 2.0g/L, diammonium hydrogen citrate 2.0g/L, sodium acetate 5.0g/L, magnesium sulfate 0.2g/L, manganese sulfate 0.04g/L, agar 14.0g/L and Tween 801.0g/L.

The components of the MRS liquid medium used in each embodiment of the present invention include: peptone 10.0g/L, beef extract powder 10.0g/L, yeast extract powder 5.0g/L, glucose 20.0g/L, magnesium sulfate 0.1g /L, sodium acetate 5.0g/L, dipotassium hydrogen phosphate 2.0g/L, ammonium citrate 2.0g/L, manganese sulfate 0.05g/L and Tween 801.0g/L.

Aroma compounds in fermented milk obtained in each embodiment of the present invention are extracted by headspace solid-phase microextraction (HS-SPME), analyzed and determined by gas chromatography-mass spectrometry (GC-MS), and the steps are as follows:

Accurately weigh 4.0g of fermented milk into a 15mL extraction bottle, add 100μL of 20mg/L 2-octanol as an internal standard, put it into the rotor, equilibrate it in a constant temperature water bath at 60°C for 5min, and extract the aged 20min The head device (75μm CAR/PDMS) was inserted into a 15mL extraction bottle, and extracted at 60°C for 40min. Then, after the extraction is completed, the extraction head is pushed into the gas phase inlet at 250°C for analysis for 5 minutes, and the extracted volatile compounds are analyzed and identified in combination with GC-MS.

The gas chromatography conditions are as follows: Chromatographic column: HP-INNOWAX (60m×0.25mm×0.25μm); inlet temperature: 250°C; temperature program: 40°C for 4min, 4°C/min to 100°C, hold for 2min, 3 ℃/min rises to 150°C, and finally rises to 230°C at 10°C/min and keeps for 5 minutes; carrier gas: helium (99.99% pure); flow rate: 1mL/min; sampling method: splitless injection. Mass spectrometry conditions: electron ionization energy: 70eV; ion source temperature: 230°C; quadrupole temperature: 150°C; emission current: 35μA; scanning speed: 1.9scans/s; mass scanning range: 30-450amu. After each analysis is completed, the extraction head needs to be aged in an aging instrument at 250°C for 20 minutes. Each sample was analyzed 3 times.

The characterization of all volatile compounds was first searched by NIST11 and Wiley7n.1 mass spectral libraries, and the compounds were preliminarily determined according to information such as matching degree and ion fragments. Retention index (RI) was calculated by using the retention time of C6-C30 n-paraffin standard substance. Combining the above two methods finally completes the characterization of volatile compounds.

The sensory evaluation descriptors and reference standards in the fermented milk obtained by screening bacterial strains in each embodiment of the present invention are as follows:

(1) Sensory acceptance test: 10 evaluators who have the habit of eating and consuming goat dairy products conducted an acceptance test on three-digit random-coded fermented milk samples in an independent sensory compartment, and the indoor temperature was maintained at 20 ℃. The five indicators of color, texture, aroma, taste and overall acceptance of the samples were evaluated respectively. Samples are scored on a 9-point preference scale (numbers 1-9 represent extremely dislike, very dislike, somewhat dislike, somewhat dislike, neither dislike nor like, somewhat like, somewhat like, very like, extremely like ).

(2) Sensory evaluation process: 15 sensory evaluators who have been screened and trained evaluate the 10 aroma attributes of fermented milk. Wine", "Sulphur", "Sour", "Animal (goat)", "Fat", "Nutty" and "Cheese". The definitions and reference samples of these 10 aroma descriptors are as follows: "Milk fragrance", 0.002% diacetyl aqueous solution; "sour taste", 0.06% lactic acid aqueous solution; "fruity fragrance", 0.002% ethyl hexanoate aqueous solution; " "Wine taste", 30% ethanol water solution; "Sulphur taste", smashed egg shell; "Sour taste", 0.1% butyric acid water solution; ", salad oil; "nutty", raw nuts; "cheese", fresh coconut meat or butter. The samples to be tested are randomly coded with numbers, each sample is cut into particles of uniform size and weighed 5g, and stored in a covered, odorless glass container (total capacity 50mL). Arrange them in random order and submit them to the evaluators for sensory evaluation test. Each aroma attribute is classified on an intensity scale of 0-10 points (intensity description: 0 = no intensity or no aroma perceived, 5 = moderate intensity, 10 = very strong).

In each embodiment of the present invention, the identification of bacterial classification adopts following method:

The strains were identified by 16S rDNA sequence. Before identification, the DNA sequence was amplified by PCR. The reaction system was: 2 μL of 27F primer (5'-GAGAGTTTGATCCTGGCTCAG-3') (SEQ ID NO: 1); 2 μL of 1492r primer (5'-TACGGCTACCTTGTTACGAC-3' ) (SEQ ID NO:2); 2 μL bacterial liquid; 19 μL of ddH2O; 25 μL of 2×Gold StarBest Mixed. The PCR reaction program is: (1) 10min at 95°C, (2) 30s at 94°C, (3) 30s at 55°C, (4) 1.5min at 72°C, repeat steps (2) to (4) for 30 cycles, (5) 72°C for 5 minutes, (6) Store at 4°C. Then the PCR product was detected by gel electrophoresis with 1.0% agarose, electrophoresed in 0.5×TAE electrophoresis solution at 100V for 20min, and then the extraction effect was detected on a gel imager, if a clear band could be seen, and If there is no obvious non-specific amplification, it can be judged that the PCR is successful. Then the 16S rDNA sequence of the strain was compared with the known strain sequence in GenBank.

Example 1

Isolate strains from fermented milk samples and prepare fermented milk, the steps are as follows:

(1) Take 1g of samples in a sterile environment (the samples mentioned are some fresh milk cakes collected from Dali, Yunnan (the ingredients of the milk cakes are goat milk and fermented whey acid water), take them back to the laboratory after sampling, and place Store in a sealed refrigerator and process as soon as possible) into a sterile test tube, add 9mL of normal saline to the test tube, fully shake and dissolve to obtain a bacterial solution with a dilution of ^10-1 ;

(2) Take 1 mL of the bacterial solution obtained in step (1) with a dilution of 10 ^-1 in another sterile test tube, add 9 mL of normal saline to the test tube, fully shake and dissolve to obtain a bacterial solution with a dilution gradient of 10 ^-2 ;

Repeat the above steps 4 times to obtain the dilutions of 10 ^-3 bacterial solution, 10 ^-4 bacterial solution, 10 ^-5 bacterial solution and 10 ^-6 bacterial solution in turn;

(3) Take 0.2 mL of the bacterial solution from the five test tubes obtained in step (2) and spread it on the MRS agar medium plate, and culture it at a constant temperature of 37°C for 2 to 3 days;

(4) Use an inoculation needle to pick up the single colonies of 60 isolates obtained after plate culture in step (3), inoculate them in MRS liquid medium respectively, and control the temperature to 37°C for constant temperature fermentation for 12 hours to obtain the fermentation liquid of 60 isolates respectively ;

(5) Centrifuge the fermented liquid of 60 isolates corresponding to step (4) at 4°C and 6000rpm for 15min, wash the precipitates obtained by centrifugation with sterile water for 2-3 times, and then place them in the cleaned precipitates Add sterile water equal to the volume of the original bacterial suspension, vortex and shake at 6000rpm for 10min, and set aside;

(6) Take about 1L of goat milk and stir it with a stirrer at 50°C for 30 minutes; then raise the temperature to 60°C, set the volume to 1L, and homogenize at 180bar; then put it in a water bath at 95°C, and when the sample temperature is 85°C, time it for 10 minutes; Then, cool to 44°C with ice cubes.

(7) Get 60 parts of the aseptic goat milk of step (6) gained, respectively calculate and insert the strain culture solution of step (5) gained by the ratio of 5% by volume, meanwhile, add commercial bacteria powder YF-L811 (5mg/ L, used to assist curdling), the temperature was controlled at 37°C for fermentation until the end of curdling fermentation (pH=4.6), and then naturally cooled to 25°C to obtain fermented milk.

Example 2

Screening bacterial strains from fermented milk samples comprises the following steps:

(1) Preparation of separation of bacterial strains and fermented milk: the same operation steps as in Example 1;

(2) The fermented milk samples obtained in step (1) were subjected to sensory evaluation preliminary screening and GC-MS aroma determination, and the lactic acid bacteria SD-3 with the functional characteristics of aroma production and odor suppression were screened, and the 16S rDNA sequence identification of the strain SD-3 was carried out. The sequence is shown as SEQ ID NO: 3, and compared with the sequence of known strains in GenBank, SD-3 is Lactococcus lactis, and the deposit number is CCTCC M2021743.

Example 3

Screening bacterial strains from fermented milk samples comprises the following steps:

(1) Preparation of separation of bacterial strains and fermented milk: the same operation steps as in Example 1;

(2) The fermented milk samples obtained in step (1) were subjected to sensory evaluation preliminary screening and GC-MS aroma determination, and the lactic acid bacteria DN-1 with the functional characteristics of aroma production and smell suppression were obtained by screening, and the 16S rDNA sequence identification of the strain DN-1 was carried out, The sequence is shown as SEQ ID NO: 4, and compared with the sequence of known strains in GenBank, DN-1 is Pediococcus lactis, and the deposit number is CCTCC M 2021794.

Example 4

Screening bacterial strains from fermented milk samples comprises the following steps:

(1) Preparation of separation of bacterial strains and fermented milk: the same operation steps as in Example 1;

(2) The fermented milk sample obtained in step (1) was subjected to sensory evaluation and GC-MS aroma determination, and was screened to obtain lactic acid bacteria GM-6 with the functional characteristics of producing aroma and suppressing mutton. The 16S rDNA sequence of strain GM-6 was identified, the sequence is shown as SEQ ID NO: 5, and compared with the sequence of known strains in GenBank, GM-6 is Lactobacillus plantarum, and the preservation number is CCTCC M 2021744.

comparative example

Commercial bacterial powder YF-L811 was inoculated into aseptic goat milk, fermented at 37°C until curd fermentation was completed (pH=4.6), cooled naturally to 25°C to obtain control fermented milk. The control fermented milk samples were screened for sensory evaluation and GC-MS aroma determination, and the changes in the content of key aroma compounds such as 2-heptanone and isoamyl alcohol and fatty acid compounds such as butyric acid, caproic acid and octanoic acid were analyzed and identified. Sensory evaluation results of aroma, fruity aroma, nutty and stinky, sour, sour taste.

The sensory indicators and aroma components of the fermented goat milk in the above-mentioned examples 2, 3, 4 and comparative examples were measured, the GC-MS identification results are shown in Table 1, and the sensory acceptance of fermented goat milk with different strains was evaluated, the results are as follows Table 2 shows.

Table 1 GC-MS determination results of fermented goat milk with different strains

Table 2 Evaluation results of sensory acceptance of fermented goat milk with different strains

color texture Taste acceptance Aroma acceptance overall acceptance SD-3 5.4±0.52 5.6±0.70 5.4±0.52 7.4±0.84 7.5±0.97 DN-1 5.5±0.53 6.0±0.82 4.7±0.95 6.9±0.74 6.7±0.67 GM-6 5.6±0.70 4.1±0.74 6.6±0.84 6.8±0.92 7.0±0.67 comparative example 5.3±0.67 4.3±0.67 5.0±0.94 5.4±0.70 5.2±0.63

As can be seen from Table 1, goat milk fermented by Lactococcus lactis SD-3, Pediococcus lactis DN-1 and Lactobacillus plantarum GM-6 produced 3 -Hydroxy-2-butanone, 2-heptanone, 2-octanone and 2-nonanone are all high in content, and the above ketone aroma substances have aroma characteristics such as cream, cheese, coconut, fruity and sweet; at the same time It also contains a high content of almond-flavored benzaldehyde and fruity-flavored isoamyl alcohol, which are used as aroma components with a suppressing effect and positive influence in the characteristic flavor identification process of curd cheese goat milk cake. At the same time, by analyzing the aroma components of the fermentation samples of different strains, it can also be seen that the fatty acids with mutton produced by the samples fermented by SD-3, DN-1 and GM-6 are different from those produced by the commercial bacteria in the comparative example. Compared with the fermented milk sample prepared by powder YF-L811, its content was also lower. That is to say, from the perspective of the production of aroma substances, the three strains of lactic acid bacteria have obvious characteristics of producing aroma and suppressing mutton when they are used to ferment goat milk.

As can be seen from Table 2, the goat milk fermented by Lactococcus lactis SD-3, Pediococcus lactis DN-1 and Lactobacillus plantarum GM-6 has a color The sensory acceptance evaluation indicators such as texture, taste acceptance, aroma acceptance and overall acceptance were all higher than the fermented milk samples prepared by commercial bacterial powder YF-L811.

According to the determined descriptive sensory analysis index, the sensory evaluation radar charts of Examples 2, 3, 4 and comparative examples are as shown in Figure 1, and it can be seen from Figure 1 that the SD-3, DN-1 and GM -6 Fermented yoghurt has higher milky, fruity and nutty flavors. According to the evaluation of the aroma quality of curd cheese goat quiche, milky aroma, fruity aroma and nutty flavor are the three types of aroma attributes accepted and loved by consumers. In addition, the muttony, sour and sour tastes of the fermented milk fermented by the three strains were also lower than those of the fermented milk fermented by commercial bacterial powder. This shows that the aroma-producing and odor-inhibiting properties of the lactic acid bacteria are good.

To sum up, the present invention provides a screening method for strains with the functional characteristics of producing aroma and suppressing mutton. The strains obtained through screening can ensure that fermentation samples can endogenously produce more milk-like aroma, Fruit aroma substances, and to a certain extent, reduce the production of muttony fatty acid components. On the basis of not needing to add aroma substances from external sources, the flavor quality of fermented milk products is optimized, and the production cost of fermented milk products is reduced.

Although the foregoing embodiments have described the present invention in detail, it is only a part of the embodiments of the present invention, rather than all embodiments, and does not limit the present invention in any form and in essence. It should be pointed out that for ordinary people in the technical field Those skilled in the art can also make some improvements and supplements without departing from the present invention, and these improvements and supplements should also be regarded as the protection scope of the present invention.

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ataagggttg cgctcgttgc gggacttaac ccaacatctc acgacacgag ctgacgacaa 420

ccatgcacca cctgtcattc tgtccccgaa gggaacgcct aatctcttag gttggcagaa 480

gatgtcaaga cctggtaagg ttcttcgcgt agcttcgaat taaaccacat gctccaccgc 540

ttgtgcgggc ccccgtcaat tcttttgagt ttcaaccttg cggtcgtact ccccaggcgg 600

attacktaat gcgttagctg cagcactgaa gggcggaaac cctccaacac ttagtaatca 660

tcgtttacgg catggactac cagggtatct aatcctgttc gctacccatg ctttcgagcc 720

tcagcgtcag ttacagacca gacagccgcc ttcgccactg gtgttcttcc atatatctac 780

gcatttcacc gctacacatg gagttccact gtcctcttct gcactcaagt ctcccagttt 840

ccaatgcact tcttcggttg agccgaaggc tttcacatta gacttaaaag accgcctgcg 900

ctcgctttac gcccaataaa tccggataac gcttgccacc tacgtattac cgcggctgct 960

ggcacgtagt tagccgtggc tttctggtta aataccgtca ctgggtgaac agttactctc 1020

accacgttc ttctttaaca acagagcttt acgagccgaa acccttcttc actcacgcgg 1080

cgttgctcca tcagacttgc gtccattgtg gaagattccc tactgctgcc tcccgtagga 1140

gtctgggccg tgtctcagtc ccaatgtggc cgattaccct ctcaggtcgg ctacgcatca 1200

tcgccttggt gagccgttac ctcaccaact agctaatgcg ccgcgggtcc atccagaagt 1260

gatagcagag ccatctttta aaagaaaacc aggcggtttt ctctgttata cggtattagc 1320

atctgtttcc aggtgttatc ccctgcttct gggcaggtta cccacgtgtt actcacccgt 1380

ccgccactca cttcgtgtta aaatctcatt cagtgcaagc acgtcctgat caattaacgg 1440

aagttcgtcg actgcattat agcgccccat tgag 1474

<210> 5

<211> 1444

<212>DNA

<213> Artificial Sequence (Artificial Sequence)

<400> 5

ttaggcggct ggttcctaaa aggttacccc accgactttg ggtgttacaa actctcatgg 60

tgtgacgggc ggtgtgtaca aggcccggga acgtattcac cgcggcatgc tgatccgcga 120

ttactagcga ttccgacttc atgtaggcga gttgcagcct acaatccgaa ctgagaatgg 180

ctttaagaga ttagcttact ctcgcgagtt cgcaactcgt tgtaccatcc attgtagcac 240

gtgtgtagcc caggtcataa ggggcatgat gatttgacgt catccccacc ttcctccggt 300

ttgtcaccgg cagtctcacc agagtgccca acttaatgct ggcaactgat aataagggtt 360

gcgctcgttg cgggacttaa cccaacatct cacgacacga gctgacgaca accatgcacc 420

acctgtatcc atgtccccga agggaacgtc taatctctta gatttgcata gtatgtcaag 480

acctggtaag gttcttcgcg tagcttcgaa ttaaaccaca tgctccaccg cttgtgcggg 540

cccccgtcaa ttcctttgag tttcagcctt gcggccgtac tccccaggcg gaatgcttaa 600

tgcgttagct gcagcactga agggcggaaa ccctccaaca cttagcattc atcgtttacg 660

gtatggacta ccagggtatc taatcctgtt tgctacccat actttcgagc ctcagcgtca 720

gttacagacc agacagccgc cttcgccact ggtgttcttc catatatcta cgcatttcac 780

cgctacacat ggagttccac tgtcctcttc tgcactcaag tttcccagtt tccgatgcac 840

ttcttcggtt gagccgaagg ctttcacatc agacttaaaa aaccgcctgc gctcgcttta 900

cgcccaataa atccggacaa cgcttgccac ctacgtatta ccgcggctgc tggcacgtag 960

ttagccgtgg ctttctggtt aaataccgtc aatacctgaa cagttactct cagatatgtt 1020

cttctttaac aacagagttt tacgagccga aacccttctt cactcacgcg gcgttgctcc 1080

atcagacttt cgtccattgt ggaagattcc ctactgctgc ctcccgtagg agtttgggcc 1140

gtgtctcagt cccaatgtgg ccgattaccc tctcaggtcg gctacgtatc attgccatgg 1200

tgagccgtta ccccaccatc tagctaatac gccgcgggac catccaaaag tgatagccga 1260

agccatcttt caagctcgga ccatgcggtc caagttgtta tgcggttatta gcatctgttt 1320

ccaggtgtta tcccccgctt ctgggcaggt ttcccacgtg ttactcacca gttcgccact 1380

cactcaaatg taaatcatga tgcaagcacc aatcaatacc agagttcgtt cgacttgcat 1440

gtat 1444

Claims (4)

1. A bacterial strain with the functional characteristics of producing aroma and suppressing mutton is characterized in that it is Lactococcus lactis SD-3, and the preservation number of said Lactococcus lactis SD-3 is CCTCC M 2021743, and its Latin name is Lactococcus lactis SD- 3. The preservation unit is the China Typical Culture Collection Center, the preservation time is June 23, 2021, and the preservation address is the Wuhan University Collection Center, Luojia Mountain, Wuchang, Wuhan City, Hubei Province. 2. A strain with the functional characteristics of producing aroma and suppressing mutton, characterized in that it is Pediococcus lactis DN-1, and the preservation number of said Pediococcus lactis DN-1 is CCTCC M 2021794, and its Latin name is Pediococcus lactis DN-1. 1. The preservation unit is the China Typical Culture Collection Center, the preservation time is June 28, 2021, and the preservation address is the Wuhan University Collection Center, Luojia Mountain, Wuchang, Wuhan City, Hubei Province. 3. A strain with the functional characteristics of producing aroma and suppressing mutton, characterized in that it is Lactobacillus plantarum GM-6, and the preservation number of said Lactobacillus plantarum GM-6 is CCTCC M 2021744, and its Latin name is Lactobacillus plantarum GM-6. 6. The preservation unit is the China Typical Culture Collection Center, the preservation time is June 23, 2021, and the preservation address is the Wuhan University Collection Center, Luojia Mountain, Wuchang, Wuhan City, Hubei Province. 4. The application of the bacterial strain with the functional characteristics of producing aroma and suppressing mutton described in any one of claims 1 to 3 in fermented goat milk.

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