Fermented butter and preparation method thereof

Abstract

The invention discloses fermented butter and a preparation method thereof, and the preparation method comprises the following steps: adding lipase into butter for enzymolysis, centrifuging to obtain supernate, adding whey powder, and adding protease for enzymolysis. Adding a rosemary extract and a compound fermentation strain A into the obtained enzymatic hydrolysate for fermentation, then adding a compound fermentation strain B for fermentation, centrifuging the fermentation liquor, collecting an oil layer, and adding the rosemary extract into the oil layer to obtain a primary product of the fermented butter; and preserving heat of the obtained primary fermented butter product at 12-18 DEG C for 2-10 hours, cooling to 4-6 DEG C at a rate of 1-4 DEG C / h, continuously preserving heat for 6-12 hours, and sterilizing to obtain the fermented butter. The fermented butter prepared by the method disclosed by the invention is free from rancidity, strong in aroma intensity and flavor durability, and good in flavor layering sense and stability.

Description

Technical Field

[0001] This invention belongs to the field of dairy product technology, and particularly relates to a fermented butter and its preparation method. Background Technology

[0002] Dairy products are an indispensable part of people's daily diet, providing comprehensive and easily absorbed nutrients. The flavor of dairy products is a crucial factor affecting their quality, primarily manifested in their milky aroma and taste. Butter, a solid fat processed from fresh milk, is an important dairy product. Its core quality depends on the richness and balance of its milk fat flavor; however, natural butter often lacks aroma intensity, flavor complexity, and stability.

[0003] Currently, the two most commonly used biological methods for flavor improvement in dairy products are enzymatic hydrolysis and microbial fermentation. Enzymatic hydrolysis mainly involves lipase hydrolysis of milk fat and protease hydrolysis of milk protein, thereby generating various flavor components for aroma enhancement; however, enzymatic hydrolysis is prone to producing oily and rancid tastes. Microbial fermentation utilizes microorganisms to ferment and hydrolyze milk proteins and milk fats in dairy products, thereby producing characteristic aroma components of dairy products; however, the aroma intensity of fermentation is poor, the aroma profile is not rich, and the flavor is easily lost. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing fermented butter, which produces fermented butter without rancidity, and with strong aroma intensity and flavor persistence, as well as good flavor layering and stability.

[0005] The technical solution of this invention is: a method for preparing fermented butter, comprising the following steps: Step 1, enzymatic hydrolysis Mix butter and water in a mass ratio of 1:1-6, add lipase for enzymatic hydrolysis; inactivate the enzyme, centrifuge, and collect the supernatant to obtain hydrolysate A; Based on enzymatic hydrolysate A, add whey powder with a mass content of 5-15% and mix well to obtain a mixture. Add protease for enzymatic hydrolysis; inactivate the enzyme, centrifuge, collect the supernatant to obtain butter whey enzymatic hydrolysate B. Step 2, Fermentation Rosemary extract was added to the butter whey hydrolysate B, the amount of which was 0.1-0.5% of the mass of the butter whey hydrolysate B; compound fermentation strain A was added, and the mixture was stirred at a constant temperature of 35-42℃ for 6-36 h to obtain fermentation liquid A; fermentation liquid A was cooled to 25-35℃, compound fermentation strain B was added, and the mixture was stirred at a constant temperature for 4-24 h to obtain fermentation liquid B; The compound fermentation strain A is a mixture of at least one of Lactococcus lactis, Lactobacillus casei, Lactobacillus bulgaricus, and Streptococcus thermophilus, and is added at 0.01-0.1% of the mass of the butter whey hydrolysate B; the compound fermentation strain B is a mixture of Lactobacillus plantarum and at least one of Kluyveromyces martensii, Saccharomyces cerevisiae, and Pichia pastoris, and is added at 0.01-0.1% of the mass of the butter whey hydrolysate B. Step 3, centrifugation Centrifuge fermentation broth B, collect the oil layer, add the rosemary extract to the oil layer, the amount added is 0.1-0.5% of the mass of fermentation broth B, mix well to obtain the initial product of fermented butter; Step 4, Post-ripening The obtained initial fermented butter product is kept at 12-18℃ for 2-10 h, then cooled to 4-6℃ at a rate of 1-4℃ / h, and kept at the temperature for another 6-12 h for sterilization to obtain fermented butter. The rosemary extract is prepared by the following method: fresh rosemary branches and leaves are refluxed with steam at 85-95℃ for 20-30 min; after cooling, 0.01-0.05 wt% of an enzyme preparation based on fresh rosemary branches and leaves is added, and enzymatic hydrolysis is carried out at 40-50℃ for 3.0-6.0 h; the enzyme is inactivated at 85℃ for 15-20 min, the filtrate is collected by centrifugation, and concentrated to a solid content of 2.0-10 wt% to obtain the rosemary extract; wherein the enzyme preparation is at least one of cellulase, pectinase, and hemicellulase.

[0006] The present invention discloses a method for preparing fermented butter. First, lipase is used to enzymatically hydrolyze the fat in the butter. After enzyme inactivation, whey powder is added, followed by enzymatic hydrolysis with protease. This step-by-step dual enzymatic hydrolysis fully utilizes the inherent components of butter—milk fat, milk protein, and lactose—resulting in a butter whey hydrolysate B rich in natural milky flavor compounds. In step two, rosemary extract is added to the butter whey hydrolysate B. This reduces the oxidation and flavor loss of aroma compounds during fermentation and harmonizes the flavor, reducing the sour and rancid taste of the finished fermented butter. After centrifuging the fermentation broth B obtained in step two, rosemary extract is added again to the collected oil layer to further harmonize the flavor and provide a favorable non-oxidative microenvironment for the post-ripening process in step four, preventing the formation of a sour and rancid taste. In step four, the initial fermented butter obtained by centrifugation after fermentation is first incubated at 12-18℃ for 2-10 h. This process stimulates the activity of aroma-producing bacteria in the initial fermented butter, promoting the further synthesis of aromatic substances during incubation. Subsequent stepwise cooling at a rate of 1-4℃ / h facilitates the orderly crystallization of fat crystals, allowing flavor substances to be fully distributed and integrated within the fat phase during crystal formation. The orderly crystallized small fat particles are more stable, effectively encapsulating the flavor substances within the droplets. This ensures the flavor substances are fully embedded in the fat crystal network, locking in the flavor and slowing down the release rate during storage. Consequently, the prepared fermented butter has a longer-lasting, more stable, and richer flavor. Furthermore, the stepped cooling process can inhibit the excessive acidification caused by the growth of harmful microorganisms and prevent the growth of heat-resistant bacteria. Therefore, it can appropriately extend the biochemical reaction time, providing sufficient time for low-temperature biochemical reactions such as enzymatic reactions to occur. This allows enzymes secreted by some bacteria that remain active only at lower temperatures to have time, sustainably, and gently modify the flavor of the finished fermented butter, improving the flavor profile and persistence.

[0007] Preferably, in step three, the fermentation broth B is centrifuged at a speed of 2000-10000 rpm for 10-20 min.

[0008] Preferably, the amount of lipase added in step one is 0.05-0.3% based on the total mass of butter and water, and the enzymatic hydrolysis conditions are to maintain 30-50℃ and stir for 3-24 hours.

[0009] Preferably, the amount of protease added in step one is 0.05-0.3% of the mass of the mixture, and the enzymatic hydrolysis conditions are 30-50°C with stirring for 3-24 hours.

[0010] Preferably, the enzyme preparation used in the preparation of the rosemary extract is a mixture of cellulase, pectinase and hemicellulase in a mass ratio of 1:0.1-0.5:0.1-0.5.

[0011] This invention provides a fermented butter, which is made using the method described above.

[0012] The beneficial effects of this invention are as follows: The method of this invention prepares fermented butter by using lipase and protease for dual enzymatic hydrolysis, and then fermenting with a complex strain after adding rosemary extract. This reduces the oxidation and loss of flavor of aroma substances and the generation of sour and rancid tastes during fermentation. The addition of rosemary extract to the initial product of fermented butter provides a non-oxidative microenvironment, preventing excessive acidification and the growth of miscellaneous bacteria. Furthermore, the stepwise cooling at a rate of 1-4℃ / h during the post-ripening process slows down the rate of biochemical reactions, allowing enzymes that remain active at lower temperatures time to sustainably and gently modify the flavor of the finished fermented butter, thereby improving the complexity and persistence of the flavor. Detailed Implementation

[0013] The present invention will now be described in detail with reference to the embodiments. Example 1

[0014] The method for preparing fermented butter is as follows: Preparation work, preparation of rosemary extract: Fresh rosemary branches and leaves were refluxed with steam at 85-90℃ for 20 min; after cooling, 0.01 wt% of an enzyme preparation based on fresh rosemary branches and leaves was added, and enzymatic hydrolysis was carried out at 40℃ for 3.0 h; the enzyme was inactivated at 85℃ for 15 min, the filtrate was collected by centrifugation, and concentrated to a solid content of 2.0 wt% to obtain rosemary extract. The enzyme preparation was a compound enzyme mixed in a mass ratio of cellulase:pectinase:hemicellulase = 1:0.1:0.1.

[0015] Step 1, enzymatic hydrolysis Mix butter and water in a 1:1 mass ratio, sterilize, and add lipase at 30°C with a mass content of 0.05% based on the total mass of butter and water. Stir at 30°C for 3 hours. Inactivate the enzyme at 85°C for 15 minutes, centrifuge at 2000 rpm for 10 minutes, and collect the supernatant to obtain enzyme hydrolysate A.

[0016] Using enzymatic hydrolysate A as a reference, 5% whey powder was added and mixed thoroughly to obtain a mixture, which was then sterilized at 85°C for 15 min. At 40°C, 0.05% protease (based on the mixture) was added, and the mixture was stirred and reacted at 40°C for 8 h. The enzyme was then inactivated at 85°C for 15 min, centrifuged at 2000 rpm for 10 min, and the supernatant was collected to obtain butter whey enzymatic hydrolysate B.

[0017] Step 2, Fermentation Add the rosemary extract prepared above to the butter whey hydrolysate B, the amount added being 0.1% of the mass of the butter whey hydrolysate B; add the compound fermentation strain A, stir at 35℃ for 6 h to obtain fermentation liquid A; cool fermentation liquid A to 25℃, add compound fermentation strain B, stir at 25℃ for 4 h to obtain fermentation liquid B.

[0018] The compound fermentation strain A is a mixture of Lactococcus lactis, Lactobacillus casei, and Lactobacillus bulgaricus in a 1:1:1 mass ratio, and is added at 0.01% of the mass of the butter whey hydrolysate B; the compound fermentation strain B is a mixture of Lactobacillus plantarum and Kluyveromyces martensii in a 1:1 mass ratio, and is added at 0.01% of the mass of the butter whey hydrolysate B.

[0019] Step 3, centrifugation The fermentation broth B was centrifuged at 2000 rpm for 10 min, and the oil layer was collected. The rosemary extract was added to the oil layer at an amount of 0.1% of the mass of the fermentation broth B. The mixture was then stirred to obtain the initial product of fermented butter.

[0020] Step 4, Post-ripening The obtained initial fermented butter was placed in a full-temperature incubator and kept at 12-15℃ for 2 hours. Then, it was cooled to 4℃ at a rate of 1℃ / h and kept at 4℃ for 6 hours to sterilize, thus obtaining fermented butter. Example 2

[0021] The method for preparing fermented butter is as follows: Preparation work, preparation of rosemary extract: Fresh rosemary branches and leaves were refluxed with steam at 90-95℃ for 25 minutes; after cooling, 0.05wt% of an enzyme preparation based on fresh rosemary branches and leaves was added, and enzymatic hydrolysis was carried out at 45℃ for 4.0 hours; the enzyme was inactivated at 85℃ for 20 minutes, and the filtrate was collected by centrifugation and concentrated to a solid content of 7.0 wt% to obtain rosemary extract. The enzyme preparation was a compound enzyme mixed in a mass ratio of cellulase:pectinase:hemicellulase = 1:0.5:0.1.

[0022] Step 1, enzymatic hydrolysis Mix butter and water at a mass ratio of 1:2, sterilize, and add lipase at 40℃ with a mass content of 0.15% based on the total mass of butter and water. Stir at 40℃ for 8 hours; inactivate the enzyme at 85℃ for 15 minutes, and centrifuge at 2000 rpm for 10 minutes to collect the supernatant to obtain enzyme hydrolysate A.

[0023] Using enzymatic hydrolysate A as a reference, 15% whey powder was added and mixed thoroughly to obtain a mixture, which was then sterilized at 85°C for 15 min. At 50°C, 0.15% protease (based on the mixture) was added, and the mixture was stirred and reacted at 50°C for 15 h. The enzyme was then inactivated at 85°C for 15 min, centrifuged at 2000 rpm for 10 min, and the supernatant was collected to obtain butter whey enzymatic hydrolysate B.

[0024] Step 2, Fermentation Add the rosemary extract prepared above to the butter whey hydrolysate B, the amount added being 0.5% of the mass of the butter whey hydrolysate B; add the compound fermentation strain A, and stir at a constant temperature of 42℃ for 36 h to obtain fermentation liquid A. Cool fermentation liquid A to 30℃, add compound fermentation strain B, and stir at a constant temperature of 30℃ for 24 h to obtain fermentation liquid B.

[0025] The compound fermentation strain A is a mixture of Lactococcus lactis, Lactobacillus casei, Lactobacillus bulgaricus, and Streptococcus thermophilus in a mass ratio of 1:1:1:1, and is added at 0.05% of the mass of the butter whey hydrolysate B; the compound fermentation strain B is a mixture of Lactobacillus plantarum, Kluyveromyces martensii, and Saccharomyces cerevisiae in a mass ratio of 1:1:1, and is added at 0.05% of the mass of the butter whey hydrolysate B.

[0026] Step 3, centrifugation The fermentation broth B was centrifuged at 10,000 rpm for 15 minutes, and the oil layer was collected. The rosemary extract was added to the oil layer at a rate of 0.5% of the mass of the fermentation broth B. The mixture was then stirred to obtain the initial product of fermented butter.

[0027] Step 4, Post-ripening The obtained initial fermented butter was placed in a full-temperature incubator and kept at 15-18℃ for 10 hours. Then, it was cooled to 5℃ at a rate of 2℃ / h and kept at 5℃ for 12 hours for sterilization, thus obtaining fermented butter. Example 3

[0028] The method for preparing fermented butter is as follows: Preparation work, preparation of rosemary extract: Fresh rosemary branches and leaves were refluxed with steam at 85-90℃ for 30 minutes; after cooling, 0.03wt% of an enzyme preparation based on fresh rosemary branches and leaves was added, and enzymatic hydrolysis was carried out at 45℃ for 5.0 hours; the enzyme was inactivated at 85℃ for 15 minutes, the filtrate was collected by centrifugation, and concentrated to a solid content of 10.0 wt% to obtain rosemary extract. The enzyme preparation was a compound enzyme mixed in a mass ratio of cellulase:pectinase:hemicellulase = 1:0.1:0.5.

[0029] Step 1, enzymatic hydrolysis Mix butter and water at a mass ratio of 1:3, sterilize, and add lipase at 50℃ with a mass content of 0.2% based on the total mass of butter and water. Stir at 50℃ for 15 hours; inactivate the enzyme at 85℃ for 15 minutes, and centrifuge at 2000 rpm for 10 minutes to collect the supernatant to obtain enzyme hydrolysate A.

[0030] Based on enzymatic hydrolysate A, 10% whey powder was added and mixed thoroughly to obtain a mixture, which was then sterilized at 85°C for 15 min. At 45°C, 0.20% protease (based on the mixture) was added, and the mixture was stirred and reacted at 45°C for 24 h. The enzyme was then inactivated at 85°C for 15 min, centrifuged at 2000 rpm for 10 min, and the supernatant was collected to obtain butter whey enzymatic hydrolysate B.

[0031] Step 2, Fermentation Add the rosemary extract prepared above to the butter whey hydrolysate B, the amount added being 0.3% of the mass of the butter whey hydrolysate B; add compound fermentation strain A, stir at 40℃ for 20 h to obtain fermentation liquid A; cool fermentation liquid A to 35℃, add compound fermentation strain B, stir at 35℃ for 16 h to obtain fermentation liquid B.

[0032] The compound fermentation strain A is a mixture of Lactococcus lactis, Lactobacillus casei, and Streptococcus thermophilus in a 1:1:1 mass ratio, and is added at 0.1% of the mass of the butter whey hydrolysate B; the compound fermentation strain B is a mixture of Lactobacillus plantarum and Saccharomyces cerevisiae in a 1:1 mass ratio, and is added at 0.1% of the mass of the butter whey hydrolysate B.

[0033] Step 3, centrifugation The fermentation broth B was centrifuged at 8000 rpm for 20 min, and the oil layer was collected. The rosemary extract was added to the oil layer at a rate of 0.3% of the mass of the fermentation broth B. The mixture was then stirred to obtain the initial product of fermented butter.

[0034] Step 4, Post-ripening The obtained initial fermented butter was placed in a full-temperature incubator and kept at 13-15℃ for 6 hours. Then, it was cooled to 6℃ at a rate of 3℃ / h and kept at 6℃ for 10 hours to sterilize, thus obtaining fermented butter. Example 4

[0035] The method for preparing fermented butter is as follows: Preparation work, preparation of rosemary extract: Fresh rosemary branches and leaves were refluxed with steam at 90-95℃ for 25 minutes; after cooling, 0.02wt% of an enzyme preparation based on fresh rosemary branches and leaves was added, and enzymatic hydrolysis was carried out at 50℃ for 6.0 hours; the enzyme was inactivated at 85℃ for 20 minutes, and the filtrate was collected by centrifugation and concentrated to a solid content of 5.0 wt% to obtain rosemary extract. The enzyme preparation was a compound enzyme mixed in a mass ratio of cellulase:pectinase:hemicellulase = 1:0.5:0.5.

[0036] Step 1, enzymatic hydrolysis Mix butter and water at a mass ratio of 1:4, sterilize, and then add lipase at 45℃ with a mass content of 0.3% based on the total mass of butter and water. Stir at 45℃ for 24 hours. Inactivate the enzyme at 85℃ for 15 minutes, and centrifuge at 2000 rpm for 10 minutes to collect the supernatant to obtain enzyme hydrolysate A.

[0037] Using enzymatic hydrolysate A as a reference, 5% whey powder was added and mixed thoroughly to obtain a mixture, which was then sterilized at 85°C for 15 min. At 30°C, 0.3% protease (based on the mixture) was added, and the mixture was stirred and reacted at 30°C for 3 h. The enzyme was then inactivated at 85°C for 15 min, centrifuged at 2000 rpm for 10 min, and the supernatant was collected to obtain butter whey enzymatic hydrolysate B.

[0038] Step 2, Fermentation Add the rosemary extract prepared above to the butter whey hydrolysate B, the amount added being 0.2% of the mass of the butter whey hydrolysate B; add compound fermentation strain A, stir at 41℃ for 15 h to obtain fermentation liquid A; cool fermentation liquid A to 25℃, add compound fermentation strain B, stir at 25℃ for 10 h to obtain fermentation liquid B.

[0039] The compound fermentation strain A is a mixture of Lactobacillus casei, Lactobacillus bulgaricus, and Streptococcus thermophilus in a 1:1:1 mass ratio, and is added at 0.02% of the mass of the butter whey hydrolysate B; the compound fermentation strain B is a mixture of Lactobacillus plantarum and Pichia pastoris in a 1:1 mass ratio, and is added at 0.02% of the mass of the butter whey hydrolysate B.

[0040] Step 3, centrifugation The fermentation broth B was centrifuged at 5000 rpm for 15 min, and the oil layer was collected. The rosemary extract was added to the oil layer at a rate of 0.4% of the mass of the fermentation broth B. The mixture was then stirred to obtain the initial product of fermented butter.

[0041] Step 4, Post-ripening The obtained initial fermented butter was placed in a full-temperature incubator and kept at 12-15℃ for 5 hours. Then, it was cooled to 5℃ at a rate of 4℃ / h and kept at 5℃ for 8 hours to sterilize, thus obtaining fermented butter.

[0042] Example 5 The method for preparing fermented butter is as follows: Preparation work, preparation of rosemary extract: Fresh rosemary branches and leaves were refluxed with steam at 85-90℃ for 20 minutes; after cooling, 0.03wt% of an enzyme preparation based on fresh rosemary branches and leaves was added, and enzymatic hydrolysis was carried out at 40℃ for 3.0 hours; the enzyme was inactivated at 85℃ for 15 minutes, the filtrate was collected by centrifugation, and concentrated to a solid content of 5.0 wt% to obtain rosemary extract. The enzyme preparation was a compound enzyme mixed in a mass ratio of cellulase:pectinase:hemicellulase = 1:0.5:0.5.

[0043] Step 1, enzymatic hydrolysis Mix butter and water at a mass ratio of 1:5, sterilize, and add lipase at 35℃ with a mass content of 0.10% based on the total mass of butter and water. Stir at 35℃ for 20 hours. Inactivate the enzyme at 85℃ for 15 minutes, centrifuge at 2000 rpm for 10 minutes, and collect the supernatant to obtain enzyme hydrolysate A.

[0044] Using enzymatic hydrolysate A as a reference, 15% whey powder was added and mixed thoroughly to obtain a mixture, which was then sterilized at 85°C for 15 min. At 40°C, 0.1% protease (based on the mixture) was added, and the mixture was stirred and reacted at 40°C for 20 h. The enzyme was then inactivated at 85°C for 15 min, centrifuged at 2000 rpm for 10 min, and the supernatant was collected to obtain butter whey enzymatic hydrolysate B.

[0045] Step 2, Fermentation Add the rosemary extract prepared above to the butter whey hydrolysate B, the amount added being 0.4% of the mass of the butter whey hydrolysate B; add the compound fermentation strain A, and stir at a constant temperature of 42℃ for 25 h to obtain fermentation liquid A. Cool fermentation liquid A to 30℃, add compound fermentation strain B, and stir at a constant temperature of 30℃ for 15 h to obtain fermentation liquid B.

[0046] The compound fermentation strain A is a mixture of Lactococcus lactis, Lactobacillus bulgaricus, and Streptococcus thermophilus in a 1:1:1 mass ratio, and is added at 0.03% of the mass of the butter whey hydrolysate B; the compound fermentation strain B is a mixture of Lactobacillus plantarum, Kluyveromyces martensii, Saccharomyces cerevisiae, and Pichia pastoris in a 1:1:1:1 mass ratio, and is added at 0.08% of the mass of the butter whey hydrolysate B.

[0047] Step 3, centrifugation The fermentation broth B was centrifuged at 3000 rpm for 15 min, and the oil layer was collected. The rosemary extract was added to the oil layer at a rate of 0.3% of the mass of the fermentation broth B. The mixture was then stirred to obtain the initial product of fermented butter.

[0048] Step 4, Post-ripening The obtained initial fermented butter was placed in a full-temperature incubator and kept at 15-18℃ for 8 hours. Then, it was cooled to 4℃ at a rate of 2℃ / h and kept at 4℃ for 7 hours to sterilize, thus obtaining fermented butter.

[0049] Example 6 The method for preparing fermented butter is as follows: Preparation work, preparation of rosemary extract: Fresh rosemary branches and leaves were refluxed with steam at 90-95℃ for 25 min; after cooling, 0.04 wt% of an enzyme preparation based on fresh rosemary branches and leaves was added, and enzymatic hydrolysis was carried out at 45℃ for 4.0 h; the enzyme was inactivated at 85℃ for 15 min, the filtrate was collected by centrifugation, and concentrated to a solid content of 6.0 wt% to obtain rosemary extract. The enzyme preparation was a compound enzyme mixed in a mass ratio of cellulase:pectinase:hemicellulase = 1:0.5:0.5.

[0050] Step 1, enzymatic hydrolysis Mix butter and water at a mass ratio of 1:6, sterilize, and add lipase at 50℃ with a mass content of 0.25% based on the total mass of butter and water. Stir at 50℃ for 10 hours; inactivate the enzyme at 85℃ for 15 minutes, and centrifuge at 2000 rpm for 10 minutes to collect the supernatant to obtain enzyme hydrolysate A.

[0051] Based on enzymatic hydrolysate A, 10% whey powder was added and mixed thoroughly to obtain a mixture, which was then sterilized at 85°C for 15 min. At 40°C, 0.25% protease (based on the mixture) was added, and the mixture was stirred and reacted at 40°C for 10 h. The enzyme was then inactivated at 85°C for 15 min, centrifuged at 2000 rpm for 10 min, and the supernatant was collected to obtain butter whey enzymatic hydrolysate B.

[0052] Step 2, Fermentation Add the rosemary extract prepared above to the butter whey hydrolysate B, the amount added being 0.3% of the mass of the butter whey hydrolysate B; add the compound fermentation strain A, and stir at a constant temperature of 43℃ for 30 h to obtain fermentation liquid A. Cool fermentation liquid A to 35℃, add compound fermentation strain B, and stir at a constant temperature of 35℃ for 20 h to obtain fermentation liquid B.

[0053] The compound fermentation strain A is a mixture of Lactococcus lactis, Lactobacillus bulgaricus, and Streptococcus thermophilus in a 1:1:1 mass ratio, and is added at 0.02% of the mass of the butter whey hydrolysate B; the compound fermentation strain B is a mixture of Lactobacillus plantarum, Saccharomyces cerevisiae, and Pichia pastoris in a 1:1:1 mass ratio, and is added at 0.1% of the mass of the butter whey hydrolysate B.

[0054] Step 3, centrifugation The fermentation broth B was centrifuged at 6000 rpm for 15 min, and the oil layer was collected. The rosemary extract was added to the oil layer at an amount of 0.2% of the mass of the fermentation broth B. The mixture was then stirred to obtain the initial product of fermented butter.

[0055] Step 4, Post-ripening The obtained initial fermented butter was placed in a full-temperature incubator and kept at 13-15℃ for 9 hours. Then, it was cooled to 4℃ at a rate of 3℃ / h and kept at 4℃ for 8 hours to sterilize, thus obtaining fermented butter.

[0056] Comparative Example 1 Prepare a fermented butter.

[0057] The method for preparing fermented butter in this comparative example differs from that in Example 1 in steps two, three, and four, as detailed below: In step two of this comparative example, rosemary extract was not added to the butter whey hydrolysate B, and everything else was exactly the same as in Example 1.

[0058] In step three of this comparative example, no rosemary extract was added to the oil layer collected by centrifugation; otherwise, it was exactly the same as in Example 1.

[0059] In this comparative example of preparing fermented butter, step four was omitted, and the process was stopped once the initial fermented oil was obtained; this was taken as the fermented butter.

[0060] Comparative Example 2 Prepare a fermented butter.

[0061] The method for preparing fermented butter in this comparative example differs from that in Example 1 only in step two. In step two of this comparative example, rosemary extract is not added to the butter whey hydrolysate B; otherwise, it is exactly the same as in Example 1.

[0062] Comparative Example 3 Prepare a fermented butter.

[0063] The method for preparing fermented butter in this comparative example differs from that in Example 1 only in step three. In step three of this comparative example, rosemary extract is not added to the oil layer collected by centrifugation; otherwise, it is exactly the same as in Example 1.

[0064] Comparative Example 4 Prepare a fermented butter.

[0065] The difference between this comparative method for preparing fermented butter and Example 1 lies in steps two and three.

[0066] In step two of this comparative example, rosemary extract was not added to the butter whey hydrolysate B, and everything else was exactly the same as in Example 1.

[0067] In step three of this comparative example, no rosemary extract was added to the oil layer collected by centrifugation; otherwise, it was exactly the same as in Example 1.

[0068] Comparative Example 5 Prepare a fermented butter.

[0069] The method for preparing fermented butter in this comparative example differs from that in Example 1 in that step four is omitted; otherwise, it is identical to Example 1. The resulting initial product of fermented butter is the fermented butter itself.

[0070] Detection: The fermented butter prepared in each embodiment and comparative example was tested using the following methods: 1. Component analysis: The fermented butter prepared in Examples 1-6 and Comparative Examples 1-5 was analyzed by headspace gas chromatography-mass spectrometry.

[0071] Testing instruments: Agilent 7693A automatic headspace sampler; Agilent GC / MS 8890 / 5976B coupled system.

[0072] Weigh 5g of sample into an extraction flask and perform headspace adsorption for 30 min at 60℃ and 200rpm using an aged SPME extraction head. Then, thermally desorb the SPME extraction head at 280℃ for 5 min in the GC-MS inlet.

[0073] Chromatographic conditions: HP-INNOWAX column; He carrier gas; flow rate 1.0 mL / min; constant pressure column temperature: initial temperature 35℃, ramped up to 240℃ at 5℃ / min and held for 10 min; injection port temperature 200℃; split ratio 20:1; transfer line temperature 280℃.

[0074] Table 1 shows the detection results of aroma substances in the products prepared in each embodiment and comparative example.

[0075] 2. Sensory evaluation: The fermented butter prepared in Examples 1 to 6 and Comparative Examples 1 to 5 was subjected to sensory evaluation.

[0076] A sensory evaluation team of 10 people was formed. Fermented butter was melted and cooled to (10±1)℃, with 5g of each sample placed in a brown glass bottle. At room temperature, the samples were evaluated and scored for their sour aroma, milky aroma, fat aroma, flavor complexity, richness, and rancidity. Each evaluator was given 5g of each sample in a brown glass bottle. The evaluators first smelled the sample and evaluated its sour aroma, milky aroma, and ester aroma; then, each sample was consumed three times consecutively, and its flavor complexity, richness, and rancidity were evaluated.

[0077] Scoring method: Appropriate sourness and aroma: 10 points; inappropriate sourness and aroma: 0 points; rich milky aroma: 10 points; weak milky aroma: 0 points; rich ester aroma: 10 points; weak ester aroma: 0 points; strong flavor complexity: 10 points; lack of complexity: 0 points; rich and full-bodied flavor: 10 points; weak and full-bodied flavor: 0 points; no rancidity: 0 points; strong rancidity: 10 points. The average score from 10 ratings is the final score. See Table 2 for detailed evaluation results.

[0078] Table 1

[0079] Table 2 Example Sour and fragrant Milk flavor Ester aroma Layers of flavor Rich and mellow Rancidity Example 1 6 5 7 5 4 0 Example 2 7 7 7 6 7 0 Example 3 8 9 8 8 8 0 Example 4 6 6 7 6 5 0 Example 5 6 6 7 7 7 0 Example 6 7 6 7 7 6 0 Comparative Example 1 4 3 4 3 3 2 Comparative Example 2 5 3 5 4 3 1 Comparative Example 3 5 3 5 4 3 1 Comparative Example 4 4 3 4 3 2 2 Comparative Example 5 5 4 4 4 2 0

[0080] The results in Table 1 show that: In Examples 1 to 6, which prepared fermented butter using the method of the present invention, the contents of butyric acid, hexanoic acid, octanoic acid, and decanoic acid were all higher than in the comparative examples; while the contents of other acids were lower than in the comparative examples. The contents of aromatic esters in each example were significantly higher than in the comparative examples. Among ketones, the content of 3-hydroxy-2-butanone (also known as acetoin) in the fermented butter prepared in each example was also significantly higher than in the comparative examples; while the contents of aldehydes in the comparative examples were significantly higher than in the examples. It is evident that the method of the present invention increases the content of important aroma compounds in dairy products such as butyric acid, hexanoic acid, octanoic acid, and decanoic acid in the prepared fermented butter, giving it a cheese and sour flavor; the characteristic flavor compounds represented by acetoin and diacetyl in the produced ketones also give the finished fermented butter a rich creamy and buttery aroma. The addition of rosemary extract effectively reduces the oxidation and flavor loss of aroma compounds during enzymatic hydrolysis, fermentation, and post-fermentation, inhibits the formation of undesirable flavor compounds such as pentanal, hexanal, and acids caused by fat oxidation, and avoids the development of a sour or rancid taste, while harmonizing and balancing the flavor. The addition of rosemary extract increases the amount of lactones with creamy, coconut, and fruity aromas, such as butylated octyl lactone and butylated decyl lactone. Simultaneously, the addition during the post-fermentation process significantly increases the accumulation of esters, enhancing the flavor complexity and warmth. Therefore, adding rosemary extract before and after fermentation of butter, through its powerful antioxidant mechanism, protects and stabilizes key aroma components that are easily oxidized and destroyed during fermentation, processing, and storage, thereby reducing the overall formation of undesirable flavor compounds and enhancing or preserving the creamy aroma, improving the sourness, milkiness, ester aroma, flavor complexity, and richness of the fermented butter, as can be seen from the data in Table 2.

[0081] It should be noted that the descriptions of these embodiments are for the purpose of aiding understanding the present invention, but do not constitute a limitation thereof. Furthermore, the technical features involved in the various embodiments of the present invention described above can be combined with each other as long as they do not conflict with each other. In addition, the above are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

Claims

1. A method for preparing fermented butter, characterized in that, Includes the following steps: Step 1, enzymatic hydrolysis Mix butter and water in a mass ratio of 1:1-6, and add lipase for enzymatic hydrolysis; Inactivate the enzyme, centrifuge, and collect the supernatant to obtain enzyme hydrolysate A; Based on enzymatic hydrolysate A, add 5-15% whey powder and mix well to obtain a mixture, then add protease for enzymatic hydrolysis; Inactivate the enzyme, centrifuge, collect the supernatant to obtain butter whey hydrolysate B; Step 2, Fermentation Rosemary extract was added to the butter whey hydrolysate B, the amount of which was 0.1-0.5% of the mass of the butter whey hydrolysate B; compound fermentation strain A was added, and the mixture was stirred at a constant temperature of 35-42℃ for 6-36 h to obtain fermentation liquid A; fermentation liquid A was cooled to 25-35℃, compound fermentation strain B was added, and the mixture was stirred at a constant temperature for 4-24 h to obtain fermentation liquid B; The compound fermentation strain A is at least three of the following: Lactococcus lactis, Lactobacillus casei, Lactobacillus bulgaricus, and Streptococcus thermophilus, and is added in an amount of 0.01-0.1% of the mass of the butter whey hydrolysate B; the compound fermentation strain B is a mixture of Lactobacillus plantarum and at least one of Kluyveromyces martensii, Saccharomyces cerevisiae, and Pichia pastoris, and is added in an amount of 0.01-0.1% of the mass of the butter whey hydrolysate B. Step 3, centrifugation Centrifuge fermentation broth B, collect the oil layer, add the rosemary extract to the oil layer, the amount added is 0.1-0.5% of the mass of fermentation broth B, mix well to obtain the initial product of fermented butter; Step 4, Post-ripening The obtained initial fermented butter product is kept at 12-18℃ for 2-10 h, then cooled to 4-6℃ at a rate of 1-4℃ / h, and kept at the temperature for another 6-12 h for sterilization to obtain fermented butter. The rosemary extract is prepared by the following method: fresh rosemary branches and leaves are refluxed with steam at 85-95℃ for 20-30 min; after cooling, 0.01-0.05 wt% of an enzyme preparation based on fresh rosemary branches and leaves is added, and enzymatic hydrolysis is carried out at 40-50℃ for 3.0-6.0 h; the enzyme is inactivated at 85℃ for 15-20 min, the filtrate is collected by centrifugation, and concentrated to a solid content of 2.0-10 wt% to obtain the rosemary extract; wherein the enzyme preparation is at least one of cellulase, pectinase, and hemicellulase.

2. The method for preparing fermented butter as described in claim 1, characterized in that, In step three, the fermentation broth B is centrifuged at a speed of 2000-10000 rpm for 10-20 minutes.

3. The method for preparing fermented butter as described in claim 1, characterized in that, The amount of lipase added in step one is 0.05-0.3% based on the total mass of butter and water, and the enzymatic hydrolysis conditions are to maintain 30-50℃ and stir for 3-24 hours.

4. The method for preparing fermented butter as described in claim 1, characterized in that, The amount of protease added in step one is 0.05-0.3% of the mass of the mixture, and the enzymatic hydrolysis conditions are to maintain the temperature at 30-50℃ and stir for 3-24 hours.

5. The method for preparing fermented butter as described in claim 1, characterized in that, The enzyme preparation used in the preparation of the rosemary extract is a mixture of cellulase, pectinase and hemicellulase in a mass ratio of 1:0.1-0.5:0.1-0.

5.

6. A fermented butter, characterized in that, It is made by any one of the methods described in claims 1-5.

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