CN115777790A

CN115777790A - Method for preparing dairy product by removing bitter milk fat and product

Info

Publication number: CN115777790A
Application number: CN202211621869.9A
Authority: CN
Inventors: 何剑; 王豪; 杜辉; 邱永乾
Original assignee: Inner Mongolia Yili Industrial Group Co Ltd
Current assignee: Inner Mongolia Yili Industrial Group Co Ltd
Priority date: 2017-01-26
Filing date: 2017-01-26
Publication date: 2023-03-14
Also published as: CN108354015A; CN108354015B

Abstract

The invention provides a method for preparing a dairy product by removing bitter milk fat and a product. The method comprises the following steps: (1) sterilizing milk fat; the milk fat is cream or cream; (2) cooling the sterilized milk fat, and then preserving heat for enzymolysis; (3) heating the milk fat subjected to enzymolysis to inactivate enzyme; (4) Cooling the enzyme-inactivated milk fat, and removing the water phase to obtain a milk fat phase; preferably when the milk fat is cream, the aqueous phase is removed by centrifugation; when the milk fat is cream, cooling the enzyme-deactivated milk fat, and pumping into a stirrer to remove water phase; (5) Storing the obtained cooled cream phase for later use or directly filling; preferably, when the milk fat is cream, the step (5) is to cool the milk fat phase obtained in the step (4) to 6-8 ℃ and store the cooled milk fat phase; when the milk fat is cream, the step (5) is to directly store the milk fat phase obtained in the step (4).

Description

Method for preparing dairy product by removing bitter milk fat and product

The application is a divisional application with the application number of 201710057382.5, the application date of 2017, 1 month and 26 days, and the invention name of the method for preparing the dairy product by removing the bitter milk fat and the product.

Technical Field

The invention relates to the field of dairy product processing, in particular to a method for preparing a dairy product by removing bitter milk fat and a product.

Background

Common dairy products in the market, such as liquid milk, yoghourt, cheese and the like, are prepared by taking raw cow (sheep) milk as a raw material and performing pasteurization or ultrahigh temperature sterilization, fermentation and other processes. The flavor of a milk product is largely affected by the original flavor of milk, and an important factor constituting the flavor of milk is milk fat. The natural milk flavor is affected by many factors such as ingredients of feed, breeds of cattle and sheep, health conditions, water quality, seasonal temperature, etc., so that milk products vary greatly in flavor from place to place. During the processing of the dairy product, heat treatment causes a series of reactions, such as esterification to form lactone, decarboxylation to form methyl ketone, maillard reaction and the like, which change the original fragrance of the milk. The flavors of dairy products of different brands and regions in the market have obvious difference, and the corresponding preference degrees of consumers also have difference. However, for most consumers, the strong flavour profile is a positive factor in dairy products.

In order to meet the demands of consumers for savoury dairy products, many recombined milk products with added essences exist in the market. In recent years, with the introduction of the global health trend of the food market, more and more consumers are pursuing dairy products without additives and essences. More and more manufacturers are then trying to enhance the flavour of milk by more natural methods, such as concentrating the milk by removing water, selecting a milk source with a higher original flavour. A modern science and technology, namely an enzymolysis technology for extracting the fragrance of the milk fat, is widely concerned because of the advantages of lower cost and no control by milk sources. The lipase acts on milk fat to specifically enzyme-cut ester bonds of triglyceride, and hydrolysis products and derivatization products have strong flavor attributes, including butyric acid with cheese aroma, ketone substances with cream aroma, butyrolactone with fresh fruit aroma and cream aroma and the like. In recent years, many researches on the enzymolysis optimization of different combinations of lipases on cream such as cream and cream have been made, but the actual commercial application is mainly limited to the preparation of essence, and the commercial examples of directly applying the enzymolysis cream to dairy products are rare. For this reason, a significant obstacle we have found in the actual product development process is that lipases often lead to the development of bitter taste, which in turn leads to the inevitable concomitant unpleasant taste of the final product while enhancing its flavor. Meanwhile, the bitter taste is retained at the root of the tongue for a long time, and the bitter taste of the finished product is enhanced due to the additive effect after the finished product is drunk in a large amount. Therefore, the removal of the bitter taste caused by the enzymolysis is a key condition for helping the industrialization of the dairy products subjected to the enzymolysis for flavor extraction.

Disclosure of Invention

One object of the present invention is to provide a method for preparing a dairy product by removing bitter milk fat;

the invention also aims to provide the dairy product prepared by the method.

To achieve the above object, in one aspect, the present invention provides a method for preparing a dairy product by removing bitter milk fat, wherein the method comprises:

(1) Sterilizing milk fat; the milk fat is cream or cream;

(2) Cooling the sterilized milk fat, and then performing heat preservation and enzymolysis;

(3) Heating the milk fat subjected to enzymolysis to inactivate enzyme;

(4) Cooling the enzyme-inactivated milk fat, and removing the water phase to obtain a milk fat phase;

(5) The resulting cooled cream phase is stored for later use or directly filled.

According to some embodiments of the invention, wherein, when the milk fat is cream, step (4) removes the aqueous phase by centrifugation.

The aqueous phase in the invention refers to other components in the milk fat except oil-soluble components such as fat.

The materials are separated after centrifugation, and the removal of the water phase can be completed through a discharge port carried by an online centrifuge.

The obtained supernatant is the supernatant of the enzymatic cream after the water phase is removed.

Pumping the supernatant into a temporary storage tank, and then cooling and storing.

The pump is a production pump which is conventional in the field of dairy production, and preferably is a pressurizing pump or a centrifugal pump.

According to some embodiments of the invention, when the milk fat is cream, the step (4) is to pump the enzyme-inactivated milk fat into a mixer after cooling to remove the aqueous phase.

According to some embodiments of the invention, wherein, when the milk fat is cream, the centrifugation of step (4) is centrifugation at a centrifugation speed of 1000-1500 g.

According to some embodiments of the invention, step (4) is centrifugation using a horizontal centrifuge.

According to some embodiments of the invention, wherein, when the milk fat is cream, the centrifugation of step (4) is centrifugation at 1000-1500g for 5-10min.

According to some embodiments of the invention, wherein, when the milk fat is cream, the step (4) is to pump the milk fat into the mixer by using a centrifugal pump or a pressurizing pump.

The operation stirrer is preferably a batch stirrer or a continuous stirrer, the operation method and parameters are the same as those of the conventional cream production process in the field, and the principle is that the enzymolysis cream is subjected to cold concentration, namely, the enzymolysis cream is stirred to break fat balls and promote the fat balls to be polymerized into fat aggregates, so that the buttermilk is discharged, and then the butter is subjected to pressure refining to remove water among the fat aggregates to obtain a blocky finished product.

According to some embodiments of the invention, wherein step (1) is sterilization at 75-90 ℃.

According to some embodiments of the invention, step (1) is sterilization at 75-90 ℃ for 30s-5min.

In the step (1), the acceptance of the milk fat refers to GB19646 standard and the internal control requirement of enterprise self-construction.

According to some embodiments of the present invention, the enzyme for enzymolysis in step (2) is lipase and/or phospholipase.

According to some embodiments of the present invention, the enzyme for enzymolysis in step (2) is a combination of lipase and phospholipase.

According to some embodiments of the invention, wherein the ratio of lipase to phospholipase is 2.

According to some embodiments of the invention, the enzyme is used in the amount of 1% to 3% in step (2); the percentages are based on the total mass of milk fat and enzyme as 100%.

According to some embodiments of the invention, the enzyme is used in an amount of 1% to 2% in step (2).

According to some embodiments of the present invention, the enzymatic hydrolysis in step (2) is performed at 44-46 ℃, and the end point of the enzymatic hydrolysis reaction is to control the pH value at 5.0-5.2.

According to some embodiments of the invention, the enzymolysis time in the step (2) is 4.5-6.5h.

According to some embodiments of the invention, when the milk fat is cream, the enzymolysis time in step (2) is 4.5-5.5h.

According to some embodiments of the invention, when the milk fat is cream, the enzymolysis time in step (2) is 5.5-6.5h.

According to some embodiments of the present invention, the cooling in step (2) is to a temperature of 44 ℃ to 46 ℃.

The equipment used for cooling in the step (2) is preferably a jacket heat preservation cylinder, a plate heat exchanger or a tubular heat exchanger.

According to some embodiments of the present invention, the enzymolysis process in step (2) further requires stirring, preferably continuous stirring, and the stirring parameter is preferably 30rpm to 50rpm.

The equipment used in the enzymolysis in the step (2) is preferably a jacket heat preservation cylinder. The jacket heat preservation cylinder needs to be connected with a CIP (on-line cleaning)/SIP (on-line disinfection) system in series.

According to some embodiments of the invention, wherein step (3) is inactivating the enzyme at 90-95 ℃.

According to some embodiments of the invention, step (3) is inactivating the enzyme at 90-95 ℃ for 15-20min.

According to some specific embodiments of the present invention, the enzyme deactivation operation in step (3) is preferably in-cylinder heating.

According to some embodiments of the invention, step (4) is cooling the enzyme-inactivated milk fat to 10-50 ℃ and removing the aqueous phase.

According to some embodiments of the invention, wherein, when the milk fat is cream, the step (4) is cooling the enzyme-inactivated milk fat to 45-50 ℃, and then removing the aqueous phase.

The cooled material is then pumped to an in-line centrifuge for separation.

Wherein, when the milk fat is cream, the cooling operation in the step (4) is preferably in-cylinder cooling.

According to some embodiments of the invention, when the milk fat is cream, the step (4) is cooling the enzyme-inactivated milk fat to 10-20 ℃, and then removing the aqueous phase.

Wherein, when the milk fat is cream, the cooling operation in the step (4) is preferably a plate heat exchanger or a tube heat exchanger.

According to some embodiments of the invention, when the milk fat is cream, the milk fat phase obtained in step (4) is cooled to 6-8 ℃ and stored for later use or directly filled in step (5).

The cooling operation is preferably in-cylinder cooling.

According to some embodiments of the invention, when the milk fat is cream, the step (5) is to directly store the milk fat phase obtained in the step (4) for use or directly fill.

The cream phase obtained in step (5) of the invention can be further added with other substances to prepare dairy products, and can also be directly filled to obtain the dairy products.

The filling is performed in compliance with the requirements of health standards operating procedures (SSOP), good Manufacturing Practice (GMP) and Hazard Analysis and Critical Control Points (HACCP).

The milk fat provided by the invention is the milk fat meeting the requirements of the national GB19646 standard in the field, and comprises cream, butter and anhydrous butter, and preferably the cream or the butter.

The enzyme provided by the invention is an enzyme meeting the requirements of national GB25594 and GB2760 standards in the field, preferably one or more of lipase and phospholipase, and most preferably lipase and phospholipase.

On the other hand, the invention also provides the dairy product prepared by the method.

In conclusion, the invention provides a method for preparing a dairy product by removing bitter milk fat and a product. The method of the invention has the following advantages:

(1) The bitter factors are inevitably introduced in the traditional process of carrying out milk fat enzymolysis, and the bitter factors remained in the milk fat enzymolysis system can be effectively eliminated through the innovation of the process, and meanwhile, the loss of aromatic substances is not caused, so that the application value of the milk fat enzymolysis is ensured. The design essence of the innovative process is to use the similar compatibility principle of solutes to separate bitter substances. In the preparation method of the invention, no special limitation is needed to be carried out on the enzymolysis substrate, and the enzymolysis substrate can be cream with lower emulsification stability in a liquid state or dilute cream with higher emulsification stability in a liquid state, wherein the former needs to be stirred in the enzymolysis process to maintain the temporary stability of a water-oil two-phase interface so as to ensure the enzymolysis effect. In the bitter removing process, the water phase and the oil phase are separated by centrifugation, and then the water phase dissolved with bitter substances is discharged, so that the separation is realized; the latter is separated by using a unique whipping type device to discharge the buttermilk containing bitter substances. During the separation process, most of the flavor substances generated based on the enzymolysis of the milk fat are fatty acid and derivatives thereof, so that the flavoring effect of the enzymolysis of the milk fat can be ensured by retaining the oil phase part.

(2) The method for performing enzymolysis on the milk fat is a natural aroma-enhancing mode based on biotechnology, avoids the addition of the traditional edible essence, and is more in line with the pursuit of consumers on healthy food. Because the final product does not contain essence, and the lipase can be used as a processing aid after inactivation without marking, the ingredients with the fragrance enhancing function in the label only need to mark the milk fat part. On the basis, the method is further characterized in that raw milk is used as a raw material, the cream is prepared on line and then is subjected to enzymolysis, so that the mark of the cream part can be further removed from the label, and the label is cleaner.

(3) Although there are many reports on the aspect of enzymolysis of milk fat, the present invention further optimizes the enzymolysis time based on the combination of lipase and phospholipase, thereby maximizing the production and retention of aromatic hydrolysate and inactivating enzyme to stop reaction before excessive enzymolysis and rancidity of fat generate unpleasant smell. The enzymatic hydrolysate is rich in pleasant cream aroma and does not have any pungent smell.

(4) The enzymolysis cream can comprehensively improve the head aroma, body aroma and tail aroma of the final product, and further improve the preference of consumers. Therefore, besides dairy products, the enzymatic hydrolysis milk fat prepared by the invention can also be applied to wider foods, such as baked desserts, ice cream, spread sauce, candies and the like, so that the taste level of the products is enriched.

(5) Because the milk fat and the enzyme preparation are standardized raw materials, and the reaction conditions are controllable factors, the flavor stability of the obtained enzymolysis products among batches is high. On the other hand, the flavor intensity of the enzymolysis milk fat is far higher than that of the original milk, so that the application of the enzymolysis milk fat can overcome the flavor fluctuation of finished products caused by the milk source difference in different regions, and the stability of the sensory quality of the products in different regions under the industrial production condition is ensured.

Drawings

FIG. 1 is a flowchart of example 1;

FIG. 2 is a flowchart of example 2;

FIG. 3 is a flowchart of example 3;

FIG. 4 is a flow chart of comparative example 1;

FIG. 5 is a flowchart of comparative example 2;

FIG. 6 is a flowchart of comparative example 3;

FIG. 7 is an optimized graph of enzymolysis time of the enzymolysis cream;

FIG. 8 is a comparison graph of flavor analysis of cream supernatant at different enzymatic hydrolysis times.

Fig. 9 and 10 are particle size distribution diagrams of comparative example 1 and example 1.

Detailed Description

The following detailed description is provided for the purpose of illustrating the embodiments and the advantageous effects thereof, and is not intended to limit the scope of the present disclosure.

Example 1 (milk)

1. The raw material formula is as follows:

94.0 percent of whole milk, 5.0 percent of concentrated milk protein and 1.0 percent of enzymolysis cream supernatant. The percentage is the mass ratio of each component relative to the milk.

The performance indexes of the raw materials meet the requirements of the conventional quality standard in the field. The enzymatic cream supernatant is obtained by the method of the invention, and the technological parameters are as follows:

1. and (3) checking and accepting cream: acceptance is required according to the standard of GB 19646;

2. cream sterilization: heating cream to 75 ℃ by using an in-cylinder heating device of a jacket heat-preservation cylinder, and preserving heat for 30 seconds to carry out sterilization treatment;

3. cooling cream and carrying out enzymolysis: cooling the sterilized cream to 44-46 ℃ by using an in-cylinder cooling device of a jacket water heat preservation cylinder, then adding lipase and phospholipase in proportion for heat preservation and enzymolysis, and opening continuous stirring in the tank during the enzymolysis process, wherein the rotating speed is controlled at 30-50 rpm. The enzymolysis reaction time is controlled to be 4.5 hours to 5.5 hours, and the pH value at the enzymolysis end point is controlled to be 5.0 to 5.2;

4. enzyme deactivation treatment and cooling: heating the cream subjected to enzymolysis to 90 ℃ by using an in-cylinder heating device of a jacket heat-preservation cylinder, preserving the heat for 20 minutes for enzyme deactivation, and then cooling to 45-50 ℃ in the cylinder;

5. extracting and preserving supernatant of the enzymatic cream: and pumping the enzyme-hydrolyzed cream which is subjected to enzyme deactivation to an online horizontal centrifuge for separation operation, wherein the centrifugal parameter is 1300g/7 min, removing the water phase, pumping the supernatant of the enzyme-hydrolyzed cream to a cylinder to be filled, refrigerating the supernatant to 6-8 ℃, and storing the supernatant for later use or directly filling the supernatant.

2. The product of this example was produced according to the following process:

1. the process flow is shown in figure 1.

2. The process is as follows:

2.1 checking and accepting raw milk: and the standard requirement of GB19301 is accepted.

2.2, preparing materials: heating the raw milk to 40-45 ℃, adding the concentrated milk protein and the supernatant of the enzymolysis cream, and circularly stirring for 30-60 minutes.

2.3, homogenizing: two-stage homogenization is carried out, the homogenization temperature is 60-65 ℃, and the homogenization pressure is 19-21 MPa.

2.4, sterilization: the sterilization temperature is 125-130 ℃; the sterilization time was 4 seconds.

2.5, cooling: cooling to 6-8 ℃, and pumping into a cylinder to be filled for filling.

2.6 filling: filling is carried out under the specified hygienic requirements.

2.7, cold storage: the product is refrigerated at 2-6 ℃ to obtain the product of the embodiment.

Example 2 (yogurt)

1. The raw material formula is as follows:

70.996 percent of skim milk, 8.0 percent of cane sugar, 20 percent of cream, 1.0 percent of enzymolysis cream supernatant and 0.004 percent of zymophyte. The percentage is the mass ratio of each component to the yoghourt.

The performance indexes of the raw materials meet the requirements of the conventional quality standard in the field. The enzymatic cream supernatant is obtained by the method, and the technological parameters are as follows:

3. cooling cream and performing enzymolysis: cooling the sterilized cream to 44-46 ℃ by using an in-tank cooling device of a jacketed water heat preservation tank, then adding lipase and phospholipase in proportion for heat preservation and enzymolysis, and opening continuous stirring in the tank during enzymolysis, wherein the rotating speed is controlled at 30-50 rpm. The enzymolysis reaction time is controlled to be 4.5 hours to 5.5 hours, and the enzymolysis end point pH is controlled to be 5.0 to 5.2;

5. extracting and preserving supernatant of the enzymatic cream: and pumping the enzyme-hydrolyzed cream which is subjected to enzyme deactivation to an online horizontal centrifuge for separation operation, wherein the centrifugal parameter is 1500g/5 min, removing the water phase, pumping the supernatant of the enzyme-hydrolyzed cream to a cylinder to be filled, refrigerating the supernatant to 6-8 ℃, and storing the supernatant for later use or directly filling the supernatant.

2. The product of this example was produced according to the following process:

1. the process flow is shown in figure 2.

2. The process is as follows:

2.2 centrifugal degreasing: an online degreasing separator is used, and the operating temperature is 50-55 ℃; the fat content of the exported cream is 42 percent, the exported cream is cooled to 6 to 8 ℃, and the exported cream is temporarily stored in a jar.

2.3 temporary storage of the skim milk: cooling the skimmed milk at the outlet to 6-8 ℃, and temporarily storing in a cylinder.

2.4, preparing materials: heating to 40-45 ℃, adding sucrose, cream and enzymolysis cream supernatant, and circularly stirring for 15-30 minutes.

2.5, homogenizing: and carrying out two-stage homogenization at 60-65 ℃ and 19-21 MPa.

2.6, sterilization: the sterilization temperature is 90-95 ℃; the sterilization time was 5 minutes.

2.7 fermentation: cooling to 40-44 deg.c, adding the fermented bacteria into the emulsion and stirring in the fermentation tank for 10-15 min to disperse the bacteria homogeneously into the emulsion. Fermenting for 7-10 hours at 40-44 ℃.

2.8, cylinder turning cooling: when the pH value reaches 4.5-4.6, the temperature is reduced to 16-22 ℃, and the mixture is injected into a temporary storage cylinder for preparation of filling.

2.9 filling: filling is carried out under the specified hygienic requirements.

2.10 after-ripening in cold storage: the product is refrigerated and then cooked at the temperature of 2-6 ℃ for more than 12 hours, and the product of the embodiment is obtained.

Example 3 (fresh cheese)

1. The raw material formula is as follows:

(1) Base material: 99.994% of skim milk, 0.004% of zymophyte and 0.002% of chymosin. The percentage is the mass ratio of each component relative to the base material

(2) Fresh cheese: 88% of whey-free base material, 7.0% of sucrose syrup, 4.0% of cream and 1.0% of enzymolysis cream (subjected to pressure refining). The percentages are mass ratios of the ingredients relative to fresh cheese.

The performance indexes of the raw materials meet the requirements of the conventional quality standard in the field. The enzymatic dilute cream (subjected to pressure refining) is obtained by the method, and the process parameters are as follows:

1. and (3) acceptance of the cream: acceptance is required according to the standard of GB 19646;

2. and (3) sterilizing cream: heating cream to 90 ℃ by using a plate heat exchanger or a tubular heat exchanger, and preserving heat for 5 minutes for sterilization treatment;

3. cooling and enzymolysis of the dilute milk oil: and (2) cooling the sterilized cream to 44-46 ℃ by using a plate heat exchanger or a tubular heat exchanger, then adding lipase and phospholipase in proportion for heat preservation and enzymolysis, and opening continuous stirring in a tank during enzymolysis, wherein the rotating speed is controlled at 30-50 rpm. The enzymolysis reaction time is controlled to be 5.5 hours to 6.5 hours, and the enzymolysis end point pH is controlled to be 5.0 to 5.2;

4. enzyme deactivation treatment and cooling: heating the diluted cream subjected to enzymolysis to 95 ℃ by using an in-cylinder heating device of a jacket heat preservation cylinder, preserving the heat for 15 minutes for enzyme deactivation treatment, and then cooling to 10-20 ℃ by using a plate heat exchanger or a tubular heat exchanger;

5. and (3) pressure refining and preservation of the enzymolysis cream: pumping the enzyme-inactivated enzymolysis dilute cream to an online stirrer for beating and refining, controlling the beating rotation speed at 50-80 rpm, removing buttermilk, pumping to a cylinder to be filled for storage or directly filling.

2. The product of this example was produced according to the following process:

1. the process flow is shown in figure 3.

2. The process is as follows:

2.2 centrifugal degreasing: the operation is carried out by using an online degreasing separator, and the operation temperature is 50-55 ℃. The protein index of the skim milk reaches 3.2 percent.

2.3 sterilization of the skim milk: the temperature of the skimmed milk is raised to 90-95 ℃, and the sterilization time is 5 minutes.

2.4 fermentation of base material: after the skim milk is cooled to 28-32 ℃, zymophyte and rennin are added, and the mixture is stirred in a fermentation tank for 10-15 minutes to uniformly disperse the strains. Fermenting for 12-16 hours at the temperature of 28-32 ℃.

2.5, removing whey: when the pH value of the base material reaches 4.5-4.6, the curd is heated to 40-44 ℃ after being stirred, the curd is pumped into a nozzle type centrifuge for centrifugal separation until the whey removal rate reaches 60 percent (the percentage is the mass ratio of the whey removed from the base material relative to the base material), and simultaneously the protein concentration is concentrated to 8.0 percent (the percentage is the mass ratio of the protein in the whey-removed base material relative to the whey-removed base material).

2.6, cylinder overturning cooling: cooling to 12-16 ℃, and putting into a temporary storage cylinder for filling.

2.7 secondary batching: the sterilized sucrose syrup, the dilute cream and the enzymolysis dilute cream are added by a metering pump (after pressure refining treatment) and are dynamically mixed with the whey-removed base material.

2.8 filling: filling is carried out under the specified hygienic requirements.

2.9 after-ripening in cold storage: the product is refrigerated and then cooked at the temperature of 2-6 ℃ for more than 12 hours, and the product of the embodiment is obtained.

COMPARATIVE EXAMPLE 1 (milk)

1. The raw material formula is as follows:

94.0 percent of whole milk, 5.0 percent of concentrated milk protein and 1.0 percent of cream supernatant. The percentage is the mass ratio of each component relative to the milk.

The performance indexes of the raw materials meet the requirements of the conventional quality standard in the field. The preparation of the cream supernatant refers to the procedure of example 1 of the present invention, but the enzyme preparation according to the present invention is not added during the preparation.

2. The product of this example was produced according to the following process:

1. the process flow is shown in figure 4.

2. The process is as follows:

2.1 checking and accepting raw milk: and (4) acceptance is required according to the standard of GB 19301.

2.2, preparing materials: heating the raw milk to 40-45 ℃, adding the concentrated milk protein and the cream supernatant, and circularly stirring for 30-60 minutes.

2.6 filling: filling is carried out under the specified hygienic requirements.

COMPARATIVE EXAMPLE 2 (yogurt)

1. The raw material formula is as follows:

70.996 percent of skim milk, 8.0 percent of cane sugar, 20 percent of cream, 1.0 percent of cream supernatant and 0.004 percent of zymophyte. The percentage is the mass ratio of each component to the yoghourt.

The performance indexes of the raw materials meet the requirements of the conventional quality standard in the field. The preparation of the cream supernatant refers to the procedure of example 2 of the present invention, but the enzyme preparation according to the present invention is not added during the preparation.

2. The product of this example was produced according to the following process:

1. the process flow is shown in figure 5.

2. The process is as follows:

2.2 centrifugal degreasing: an online degreasing separator is used, and the operation temperature is 50-55 ℃; the fat content of the exported cream is 42 percent, the exported cream is cooled to 6 to 8 ℃, and the exported cream is temporarily stored in a jar.

2.4, preparing materials: heating to 40-45 ℃, adding cane sugar, cream and cream supernatant, and circularly stirring for 15-30 minutes.

2.9 filling: filling is carried out under the specified hygienic requirements.

2.10 after-ripening in refrigeration: the product is refrigerated and then cooked at the temperature of 2-6 ℃ for more than 12 hours, and the product of the embodiment is obtained.

COMPARATIVE EXAMPLE 3 (fresh cheese)

1. The raw material formula is as follows:

(1) Base material: 99.994% of skim milk, 0.004% of zymophyte and 0.002% of chymosin. The percentage is the mass ratio of each component relative to the base material.

(2) Fresh cheese: 88% of whey-free base material, 7.0% of sucrose syrup, 4.0% of cream and 1.0% of cream (subjected to pressure refining). The percentages are mass ratios of the ingredients relative to fresh cheese.

The performance indexes of the raw materials meet the requirements of the conventional quality standard in the field. The preparation of cream (subjected to the milling treatment) refers to the procedure of example 3 of the present invention, but the enzyme preparation according to the present invention is not added during the preparation process.

2. The product of this example was produced according to the following process:

1. the process flow is shown in figure 6.

2. The process is as follows:

2.4, fermenting the base material: after the skim milk is cooled to 28-32 ℃, zymophyte and rennin are added, and the mixture is stirred in a fermentation tank for 10-15 minutes to uniformly disperse the strains. Fermenting for 12-16 hours at the temperature of 28-32 ℃.

2.5 whey removal: when the pH value of the base material reaches 4.5-4.6, demulsifying, heating to 40-44 ℃, pumping into a nozzle type centrifuge for centrifugal separation until the whey removal rate reaches 60% (the percentage is the mass ratio of the whey removed from the base material relative to the base material), and simultaneously concentrating the protein concentration to 8.0% (the percentage is the mass ratio of the protein in the whey-removed base material relative to the whey-removed base material).

2.7 secondary batching: the sterilized sucrose syrup, cream and cream (through pressure refining) are added by a metering pump and dynamically mixed with the whey-removed base material.

2.8 filling: filling is carried out under the specified hygienic requirements.

Effect example 1

Sensory test evaluation analysis shows that the enzymatic cream precipitate has a very strong bitter character, while the enzymatic cream supernatant has no bitter character. Further, the proteolysis rate analysis is carried out on the supernatant of the enzymatic cream and the precipitate of the enzymatic cream, the proteolysis rate analysis is determined by an o-phthalaldehyde (OPA) color development method, the determination principle is that the OPA and free alpha-amino can form a yellow compound in the presence of beta-mercaptoethanol, the yellow compound has characteristic absorption at 340nm, and the OD value of the yellow compound can be detected by a spectrophotometer. The results are shown in Table 1.

TABLE 1

	Enzymatic cream supernatant	Enzyme-hydrolyzed cream precipitate
			Hydrolysis ratio of protein (%)	5.1	68

From the above data analysis, it can be seen that the enzymatic cream precipitate has a higher proteolysis rate, which is consistent with the sensory evaluation test results. The higher the proteolytic rate, the higher the content of oligopeptides produced by hydrolysis in the system and the higher the corresponding content of bitter peptides, which supports the inventors' previous hypothesis that bitter factors are present in the precipitate of enzymatically hydrolyzed milk fat.

Effect example 2

And (3) carrying out a time gradient experiment on the enzymolysis time related to the first method of the invention, and analyzing the aroma intensity and the pH value of the enzymolysis cream, thereby optimizing the reaction time of enzymolysis. Wherein, the experimenters participating in the evaluation of the aroma intensity all receive professional sensory training for 6 persons in total, the scoring interval is 1 to 6 points, and the scoring is carried out according to the intensity degree of the senses.

From the analysis of fig. 7, it can be seen that the pH of the cream decreased significantly in the first 3 hours and decreased gradually in the subsequent 4 hours as the enzymatic reaction proceeded. After 5 hours of enzymolysis, the pH value of the product is stable. From sensory analysis, the enzymolyzed cream supernatant with the enzymolysis time of 5 hours has the highest tail scent/aftertaste score, while the tail scent/aftertaste of the enzymolyzed cream supernatant with the enzymolysis time of 3 hours is slightly insufficient, and the tail scent/aftertaste of the enzymolyzed cream supernatant with the enzymolysis time of 7 hours is too strong to generate convergence.

The data corresponding to fig. 7 is shown in the following table:

time (h)	0	3	5	7
					pH value	6.63	5.5	5.37	5.32
Sensory scoring	0	4.5	5	4.2

In summary, for the method one of the present invention, the optimized enzymatic time was determined to be 5 hours.

Effect example 3

The method of the invention I analyzes the free fatty acid component of the enzymolysis cream supernatant fluid with different enzymolysis time, and objectively reflects the corresponding sensory analysis result in figure 2 through qualitative and quantitative analysis of flavor substances. The detection method for analyzing the free fatty acid component refers to GB 5413.27-2010, and the related detection results are shown in figure 8.

From the analysis of the above graph, it can be seen that the content of free fatty acid in the supernatant of cream subjected to 5 hours of enzymatic hydrolysis was higher. The free fatty acid can give unique cream and cream fragrance to the finished product, and the data analysis result proves that the cream supernatant subjected to enzymolysis for 5 hours has better flavor.

Effect example 5

The products produced in inventive example 1 and comparative example 1 were subjected to an in-system particle size distribution test analysis, which was referred to the specification of Malvern particle size Analyzer Hydro2000 Mu. The particle size analysis chart of comparative example 1 is shown in FIG. 9, and the particle size analysis chart of example 1 is shown in FIG. 10.

From the analysis of fig. 9, it can be seen that the particle size distribution of the system of the product without using the enzyme-hydrolyzed cream supernatant is in a distinct gaussian distribution, i.e. the average value, the median value and the mode value are exactly at the same position, which indicates that the system is in a relatively stable state. As can be seen from the analysis in fig. 10, the particle size distribution of the product obtained using the enzyme-hydrolyzed cream supernatant was different from that of fig. 4, and the system did not exhibit a gaussian distribution. Nevertheless, the particle size distribution of fig. 10 is only unimodal and does not result in bimodal or multimodal states, indicating that the product stability is also better. The reason for this is that, since the supernatant of the enzyme-hydrolyzed cream contains a large amount of free fatty acids, a curve superposition effect occurs in a particle size range smaller than the average particle size.

Claims

1. A preparation method of debittered milk fat, wherein the method comprises the following steps:

(1) Sterilizing milk fat; the milk fat is cream or cream;

(2) Cooling the sterilized milk fat, and then performing heat preservation and enzymolysis; the enzyme for enzymolysis is the combination of lipase and phospholipase;

(3) Heating the milk fat subjected to enzymolysis to inactivate enzyme;

(4) Cooling the enzyme-inactivated milk fat, and removing the water phase to obtain a milk fat phase; preferably when the milk fat is cream, the aqueous phase is removed by centrifugation; when the milk fat is cream, cooling the enzyme-deactivated milk fat, and pumping into a stirrer to remove water phase;

(5) Storing the obtained cooled cream phase for later use or directly filling; preferably, when the milk fat is cream, the step (5) is to cool the milk fat phase obtained in the step (4) to 6-8 ℃ and store the cooled milk fat phase; when the milk fat is cream, the step (5) is to directly store the milk fat phase obtained in the step (4).

2. The method according to claim 1, wherein the method comprises at least one of the following features (a), (b), (c), (d):

(a) Sterilizing at 75-90 deg.C for 30s-5min;

(b) The ratio of the lipase to the phospholipase in the step (2) is 2:1;

(c) The dosage of the enzyme in the step (2) is 1 to 3 percent; preferably 1% -2%; the percentage is based on the total mass of the milk fat and the enzyme being 100%;

(d) The enzymolysis in the step (2) is carried out at 44-46 ℃, and the reaction end point of the enzymolysis is to control the pH value to be 5.0-5.2; the preferred enzymolysis time is 4.5-6.5h; preferably, when the milk fat is cream, the enzymolysis time in the step (2) is 4.5-5.5h; when the milk fat is cream, the enzymolysis time in the step (2) is 5.5-6.5h.

3. The method according to claim 1 or 2, wherein the method further comprises at least one of the following features (e), (f):

(e) When the milk fat is cream, the centrifugation in the step (4) is carried out for 5-10min at the centrifugation rotating speed of 1000-1500 g; preferably, the step (4) is performed by using a horizontal centrifuge;

(f) Step (4) cooling the enzyme-inactivated milk fat to 10-50 ℃, and then removing the water phase; preferably, when the milk fat is cream, the step (4) is to cool the milk fat after enzyme deactivation to 45-50 ℃; when the milk fat is cream, the step (4) is to cool the milk fat after enzyme deactivation to 10-20 ℃.

4. The method according to any one of claims 1 to 3, wherein the method further comprises at least one of the following features (g), (h):

(g) Step (3) inactivating enzyme at 90-95 deg.C for 15-20min;

(h) When the milk fat is cream, the step (4) is to pump the milk fat into the mixer by using a centrifugal pump or a pressurizing pump.

5. The method according to claim 1, wherein the bitter taste is predominantly a residual bitter taste in an enzymolysed milk fat system.

6. The method of claim 1, wherein the method does not include the step of adding a fragrance.

7. Debittered milk fat prepared by the process of any one of claims 1 to 6.

8. A dairy product comprising the debittered milk fat of claim 7; preferably the dairy product is liquid milk, yoghurt or cheese; preferably the dairy product contains aroma substances produced by the enzymatic hydrolysis of milk fat.

9. A food product comprising the de-bittered milk fat of claim 7 or the dairy product of claim 8; preferably, the food product is a baked dessert, ice cream, spread or candy.

10. Use of the milk fat according to any of claims 7 to 9 for overcoming the fluctuations in the final flavor due to differences in milk sources in different regions, thereby ensuring the stability of the organoleptic quality of the product between different regions under industrial production conditions.