Biological enzyme treatment method for improving yield and quality of sheep cheese

Abstract

The invention relates to the technical field of food, in particular to a biological enzyme treatment method for improving the yield and quality of goat cheese, the biological enzyme treatment method takes fresh goat milk as raw milk, biological enzyme and phenolic acid are adopted for treatment, and the biological enzyme is laccase or tyrosinase. According to the biological enzyme treatment method disclosed by the invention, the sheep cheese is produced and processed by adopting combined treatment of specific types of biological enzymes and phenolic acids, the prepared cheese product has the characteristics of high yield and high milk solid matter recovery rate, the economic value is higher, the quality of the product is well maintained in the storage period, and the shelf life is obviously prolonged. The sheep cheese produced and processed by adopting the biological enzyme treatment method disclosed by the invention is flat and glossy in surface, fine and smooth in tissue state, harmonious in milk flavor, golden in surface after being baked, moderate in hardness and excellent in sensory quality.

Description

Technical Field

[0001] The invention relates to the field of food technology, and in particular to a biological enzyme treatment method for improving the yield and quality of goat cheese. Background Art

[0002] Goat milk is one of the three major sources of milk in the world. It has a unique flavor, is easy to digest and absorb, and has low allergenicity. It is also rich in nucleotides, epidermal growth factor, insulin-like growth factor and other active ingredients. It is recognized as a nutritional product that is closer to human milk than cow's milk. As consumers' awareness of the nutritional value and health functions of goat milk increases, the goat milk market has increasingly become a focus of competition for dairy companies. However, the current domestic market has a single variety of goat milk products, mainly adult goat milk powder and infant formula goat milk powder. There is a lack of products that can meet the diversified needs of consumers, which puts forward an urgent need for the creation and development of new goat milk products.

[0003] Cheese is a solid dairy product made by curdling and separating whey with proteins (mainly casein) in milk or other milk raw materials under the action of rennet or other coagulants. As a high-value dairy product with both nutritional and health characteristics, cheese is rich in protein, fat, calcium, phosphorus, potassium, carotenoids, vitamins and other nutrients. It has many physiological functions such as enhancing the body's immunity, promoting bone health, protecting eyes, maintaining intestinal health, and preventing cardiovascular diseases. It is known as the "gold of milk". However, influenced by traditional dietary habits and residents' cognitive concepts, there are only a small number of ethnic cheeses and cow cheese products in circulation in the domestic cheese market. The goat cheese market is almost completely blank, and there is a lack of goat cheese products suitable for Chinese consumption. Due to the obvious differences in nutritional composition between goat milk and cow milk, especially the casein content and proportion, there are many differences between goat cheese and cow cheese in terms of coagulation characteristics, processing technology, product taste and texture. There are technical problems such as low product yield, poor coagulation performance, insufficient functional characteristics, and short shelf life in the production and processing of goat cheese. At present, different methods have been reported, including adding whey protein or other cheese by-products and applying physical treatment methods (such as ultrafiltration, high hydrostatic pressure, ultra-high pressure homogenization, etc.) to increase cheese production, improve product texture or extend shelf life, but these treatments may also damage the cheese structure, flavor or sensory characteristics, and increase investment and operation and maintenance costs. Therefore, the development of new technologies with high efficiency and low cost to increase the production and quality of goat cheese is of great significance and role in improving the economic value of the goat milk industry and accelerating the development of goat cheese. Summary of the invention

[0004] The invention provides a biological enzyme treatment method for improving the yield and quality of goat cheese, which is used to solve the problems of low product yield, poor quality, short shelf life and the like in the existing goat cheese preparation method.

[0005] According to a first aspect of the present invention, the present invention provides a bio-enzyme treatment method for improving the yield and quality of goat cheese, using fresh goat milk as raw milk, and using bio-enzyme and phenolic acid for combined treatment, wherein the bio-enzyme is laccase or tyrosinase.

[0006] In the above scheme, polyphenol oxidases such as laccase and tyrosinase can react with proteins through covalent bonds mediated by active substances produced by enzymatic catalysis, thereby generating a protein network, and can further promote the cross-linking reaction between laccase and tyrosinase and proteins under the action of phenolic acid small molecule redox substances. The present invention provides a biological enzyme treatment method for improving the yield and quality of goat cheese, using fresh goat milk as raw milk, and using a specific type of biological enzyme and phenolic acid for combined treatment for production and processing. The prepared goat cheese has the characteristics of high yield and high milk solid recovery rate, and has higher economic value. The goat cheese produced and processed by the biological enzyme treatment method of the present invention has a smooth and shiny surface, a delicate texture, and a coordinated milk flavor. After baking, the surface is golden, the hardness is moderate, and the sensory quality is excellent.

[0007] Furthermore, the phenolic acid comprises one or more of chlorogenic acid, caffeic acid and ferulic acid, preferably chlorogenic acid or caffeic acid.

[0008] In some specific embodiments, when the biological enzyme is laccase, the phenolic acid is chlorogenic acid. In other specific embodiments, when the biological enzyme is tyrosinase, the phenolic acid is caffeic acid.

[0009] Experiments have found that the performance of goat cheese produced by the combined treatment of laccase and chlorogenic acid, or tyrosinase and caffeic acid, is better.

[0010] Further, the following steps are included: The raw milk is filtered to remove impurities, heated at 70-75°C for 10-20s, and then cooled to 35-40°C; the pH is adjusted to 6-6.5, and then biological enzymes and phenolic acid are added and incubated for 0.5-1.5h; rennet and calcium chloride are added, and the curd is cut after standing for 20-40min; the curd is stood for 3-8min, and then heated to 40-50°C within 10-20min and continuously stirred, the whey is discharged, and the whey is pressed in a mold for 0.5-1.5h; the cheese is blanched in 85-95°C whey for 20-40min to obtain cheese; after removing the moisture on the surface of the cheese, edible salt is evenly applied, and the cheese is stored in a vacuum at 3-5°C.

[0011] Furthermore, the concentration of the biological enzyme is 1-30 U / g, preferably 6-20 U / g.

[0012] In some specific embodiments, when the biological enzyme is laccase, the concentration is preferably 10-30 U / g, more preferably 15-25 U / g, and more preferably 20 U / g.

[0013] In some specific embodiments, when the biological enzyme is tyrosinase, the concentration is preferably 1-10 U / g, more preferably 5-7 U / g, and more preferably 6 U / g.

[0014] In the above scheme, by limiting the addition amount of the biological enzyme within a reasonable range, it is beneficial to improve the yield and recovery rate of goat cheese, and at the same time, it can also improve the sensory quality of the goat cheese.

[0015] Furthermore, the amount of phenolic acid added is 1-4 mM, preferably 1.5-2.5 mM, and more preferably 2 mM relative to the raw milk.

[0016] In the above scheme, by limiting the addition amount of phenolic acid within a reasonable range, it is beneficial to improve the yield and recovery rate of goat cheese, and at the same time, it can also improve the sensory quality of goat cheese.

[0017] Furthermore, relative to the raw milk, the added amount of rennet is 0.03-0.05 g / L.

[0018] In the above scheme, rennet is a complex enzyme, mainly including pepsin and gastric lipase. Rennet can coagulate goat milk, form a curd network, determine cheese texture, promote cheese maturation, increase cheese yield, accelerate the cheese production process, and affect cheese melting characteristics in the production of goat cheese. By limiting the amount of rennet added within a reasonable range, the quality and consistency of the cheese can be ensured.

[0019] Furthermore, relative to the raw milk, the added mass percentage of calcium chloride is 0.005-0.015%.

[0020] In the above scheme, calcium chloride is used as an auxiliary agent in the production process of goat cheese, which can enhance curdling, improve cheese texture, promote cheese maturation, increase cheese yield, adjust cheese melting characteristics, stabilize microorganisms in cheese, reduce whey production and improve the nutritional value of cheese. By limiting the addition amount of calcium chloride to a reasonable range, the final quality of cheese, including taste, flavor and appearance, can be improved.

[0021] Furthermore, the amount of edible salt added is 1-3% of the weight of the final cheese product.

[0022] Furthermore, before the vacuum storage, the product is wrapped with an edible composite film of chitosan-whey protein-mint essential oil.

[0023] In the above scheme, edible salt plays a role in enhancing flavor, inhibiting microbial growth, promoting cheese maturation, improving cheese preservation, improving cheese texture and structure, promoting whey discharge and increasing the nutritional value of cheese during the production process of goat cheese. By limiting the amount of edible salt added within a reasonable range, it is beneficial to improve the taste and shelf life of the cheese, and ensure that the desired preservation and flavor effects are achieved.

[0024] Furthermore, the yield of the cheese is greater than or equal to 9%.

[0025] In some specific embodiments, the yield of goat cheese obtained by treating with laccase and chlorogenic acid is 10.39±0.06%.

[0026] In other specific embodiments, the yield of goat cheese obtained by treating tyrosinase with caffeic acid is 9.28±0.08%.

[0027] According to the second aspect of the present invention, the present invention also provides a goat cheese prepared by the above-mentioned biological enzyme treatment method.

[0028] Preferably, in some specific embodiments, the yield of goat cheese produced by laccase combined with chlorogenic acid treatment is 10.39±0.06%, and the nutritional indicators are moisture content 45.54±0.74%, total solid content 54.46±0.74%, fat content 25.87±0.20%, protein content 24.00±0.12%, and pH 6.30±0.01.

[0029] In other specific embodiments, the yield of goat cheese produced by tyrosinase combined with caffeic acid treatment is 9.28±0.08%, and the nutritional indicators are moisture content 36.25±0.78%, total solid content 63.75±0.78%, fat content 29.03±0.22%, protein content 25.63±0.11%, and pH 6.47±0.03.

[0030] Beneficial effects of the present invention: The method for preparing goat cheese of the present invention uses fresh goat milk as raw milk, and combines laccase and chlorogenic acid, or tyrosinase and caffeic acid treatment to produce and process goat cheese. The prepared goat cheese has the characteristics of high yield and high milk solid recovery rate, and has higher economic benefits.

[0031] The sheep cheese produced and processed by the invention has a smooth and glossy surface, a fine texture, a harmonious milk flavor, a golden surface after baking, moderate hardness and softness, and excellent sensory quality.

[0032] The method for preparing goat cheese of the present invention can effectively slow down the growth of microorganisms, protein hydrolysis and fat oxidation during the cold storage of goat cheese, delay the softening of cheese, improve the storage quality of cheese, and extend the shelf life of goat cheese under cold storage conditions from 40 days to more than 50-55 days. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] Example 1

[0035] This embodiment provides a biological enzyme treatment method for improving the yield and quality of goat cheese, comprising the following steps: Filter the raw milk to remove impurities → heat at 72℃ for 15s → cool to 38℃ → adjust pH to 6.0 → add laccase (20U / g protein) and phenolic acid (chlorogenic acid 2mM) and incubate for 1h → add rennet (0.035 g / L milk) and 0.01% calcium chloride → stand for 30min and cut into 1cm 3 Curd → let stand for 5 minutes, heat to 45℃ within 15 minutes and stir continuously → discharge whey, squeeze in mold for 1 hour → scald in 90℃ whey for 30 minutes → remove moisture from cheese surface and evenly apply 2% edible salt → directly store at 4℃ in vacuum.

[0036] The nutritional indicators of the goat cheese obtained in this example are: moisture content 45.54±0.74%, total solid content 54.46±0.74%, fat content 25.87±0.20%, protein content 24.00±0.12%, and pH 6.30±0.01.

[0037] Example 2

[0038] This embodiment provides a bio-enzyme treatment method for improving the yield and quality of goat cheese, which is different from Embodiment 1 in that caffeic acid of the same concentration is used instead of chlorogenic acid.

[0039] Example 3

[0040] This embodiment provides a bio-enzyme treatment method for improving the yield and quality of goat cheese, which is different from Embodiment 1 in that ferulic acid of the same concentration is used instead of chlorogenic acid.

[0041] Comparative Example 1

[0042] This comparative example provides a biological enzyme treatment method for improving the yield and quality of goat cheese, which is different from Example 1 in that laccase and phenolic acid are not added.

[0043] Comparative Example 2

[0044] This comparative example provides a biological enzyme treatment method for improving the yield and quality of goat cheese, which is different from Example 1 in that the amount of phenolic acid added is 0.

[0045] Example 4

[0046] This embodiment provides a bio-enzyme treatment method for improving the yield and quality of goat cheese, which is different from Example 1 in that the pH after sterilization and cooling is adjusted to 6.3, and 6 U / g protein tyrosinase is used instead of 20 U / g protein laccase.

[0047] Example 5

[0048] This embodiment provides a bio-enzyme treatment method for improving the yield and quality of goat cheese, which is different from Example 4 in that caffeic acid of the same concentration is used instead of chlorogenic acid.

[0049] The nutritional indicators of the goat cheese obtained in this example are as follows: moisture content 36.25±0.78%, total solid content 63.75±0.78%, fat content 29.03±0.22%, protein content 25.63±0.11%, and pH 6.47±0.03.

[0050] Example 6

[0051] This embodiment provides a bio-enzyme treatment method for improving the yield and quality of goat cheese, which is different from Example 4 in that ferulic acid of the same concentration is used instead of chlorogenic acid.

[0052] Comparative Example 3

[0053] This comparative example provides a biological enzyme treatment method for improving the yield and quality of goat cheese, which is different from Example 4 in that the amount of phenolic acid added is 0.

[0054] The effects of the treatment methods of Examples 1-6 and Comparative Examples 1-3 on the yield and recovery rate of goat cheese are shown in Table 1.

[0055] Table 1 Effect of enzyme combined with phenolic acid treatment on yield and recovery rate of goat cheese

[0056] Note 1: Different superscript lowercase letters indicate significant differences between samples in the same column ( p <0.05).

[0057] The appearance of the goat cheese obtained by laccase combined with caffeic acid treatment was an unacceptable dark green, which seriously affected the sensory organs, so no follow-up research was conducted; the cheeses in the laccase combined with chlorogenic acid and ferulic acid treatment groups all showed normal goat cheese conditions, but only the laccase combined with chlorogenic acid treatment group could significantly improve the yield and nutrient recovery rate of goat cheese. It can be seen from the results in Table 1 that compared with the control group (CK), the yield, corrected yield, fat recovery rate, protein recovery rate, and total solid recovery rate were increased by 1.69%, 0.77%, 10.9%, 10.13%, and 3.92%, respectively; compared with laccase treatment alone, the yield, corrected yield, fat recovery rate, protein recovery rate, and total solid recovery rate were increased by 0.36%, 0.48%, 5.06%, 3.7%, and 2.45%, respectively.

[0058] The cheeses treated with tyrosinase combined with phenolic acid all showed normal goat cheese state, but compared with the group treated with tyrosinase alone, the yield of goat cheese obtained by tyrosinase combined with chlorogenic acid and ferulic acid treatment decreased. Only the group treated with tyrosinase combined with caffeic acid could significantly improve the yield and nutrient recovery rate of goat cheese. Compared with the control group (CK), the yield, corrected yield, fat recovery rate, protein recovery rate and total solid recovery rate were increased by 0.58%, 1.24%, 11.41%, 6.24% and 6.35%, respectively; compared with tyrosinase alone, the yield, corrected yield, fat recovery rate, protein recovery rate and total solid recovery rate were increased by 0.25%, 0.93%, 8.84%, 4.12% and 4.79%, respectively.

[0059] It can be seen that laccase combined with chlorogenic acid treatment, or tyrosinase combined with caffeic acid treatment showed obvious advantages in improving goat cheese yield and nutrient recovery rate.

[0060] The combined treatment of biological enzymes and phenolic acid affects the sensory quality of goat cheese in terms of appearance, texture, flavor, and function. The goat cheese in the CK group had a harder texture, average chewing feel, average color brightness, a lighter milky aroma, and a higher oil yield after baking. The goat cheese treated with laccase alone had a smoother surface, a slightly softer texture, an average chewing feel, no obvious goat milk smell, and a moderate amount of oil on the surface of the cheese after baking. The appearance of goat cheese treated with laccase combined with caffeic acid was an unacceptable dark green, which seriously affected the senses. The surface of goat cheese treated with laccase combined with chlorogenic acid or ferulic acid was bright and shiny, with a delicate taste and harmonious milky aroma. The cheese was moderately soft and hard after baking, and the oil yield was moderate, but the laccase combined with chlorogenic acid treatment group had a more obvious advantage in texture, and the tissue state was more delicate, uniform and elastic.

[0061] The surface of goat cheese treated with tyrosinase alone, tyrosinase combined with chlorogenic acid, caffeic acid or ferulic acid was bright and shiny, and the cheese was golden yellow after baking, with moderate oil yield and no charring. However, the milk flavor of goat cheese treated with tyrosinase combined with chlorogenic acid was lighter, the texture of goat cheese treated with tyrosinase combined with ferulic acid was slightly harder, and the milk flavor of goat cheese treated with tyrosinase combined with caffeic acid was strong, with moderate hardness and softness, and delicate taste.

[0062] Example 7

[0063] This embodiment provides a biological enzyme treatment method for improving the yield and quality of goat cheese, which is different from Example 1 in that the addition amount of laccase is 10 U / g protein.

[0064] Example 8

[0065] This embodiment provides a biological enzyme treatment method for improving the yield and quality of goat cheese, which is different from Example 1 in that the addition amount of laccase is 30 U / g protein.

[0066] The effects of the treatment methods of Examples 7-8 on the yield and recovery rate of goat cheese are shown in Table 2.

[0067] Table 2 Effects of different concentrations of laccase combined with chlorogenic acid on the yield and recovery of goat cheese

[0068] Note 2: Different superscript lowercase letters indicate significant differences between samples in the same column ( p <0.05).

[0069] As shown in Table 2, the laccase treatment concentration has a significant difference in the yield and recovery rate of goat cheese: the yield of goat cheese can be significantly increased by appropriately increasing the laccase treatment concentration. Compared with the control, when the laccase treatment amount was 10U / g protein, the yield, corrected yield and total solid recovery rate did not increase significantly; when the laccase treatment amount was 20U / g protein, the goat cheese yield was 1.69% higher than that of the CK group (8.70±0.13%), the corrected yield was 0.77% higher than that of the CK group (9.66±0.06%), and the total solid recovery rate was 3.92% higher than that of the CK group (49.49±0.33%). However, when the laccase treatment amount continued to increase to 30U / g protein, obvious flocculation and precipitation appeared at the bottom of the material, and normal uniform coagulants could not be formed, and the yield was significantly reduced. It can be seen that the appropriate laccase treatment concentration (20U / g protein) combined with chlorogenic acid to produce and process goat cheese can maximize the cheese yield and recovery rate.

[0070] In addition, there are obvious differences in the sensory properties of goat cheese produced by different concentrations of laccase combined with chlorogenic acid. Compared with low concentrations, when the laccase treatment concentration is 20U / g protein, the surface of the produced and processed goat cheese is smoother, brighter and more lustrous, with a uniform texture, moderate hardness, rich flavor, and no obvious goat milk smell. After baking, the surface of the cheese is golden yellow, the oil yield is moderate, and there is no coking phenomenon; when the laccase treatment concentration is increased to 30U / g protein, the cheese is difficult to form and the surface is uneven.

[0071] Examples 9-11

[0072] This example provides a biological enzyme treatment method for improving the yield and quality of goat cheese, which is different from Example 5 in that the addition amount of tyrosinase is 1.5U / g protein, 3U / g protein, and 10U / g protein, respectively. The effects of the treatment methods of Examples 9-11 on the yield and recovery rate of goat cheese are shown in Table 3.

[0073] Table 3 Effects of different concentrations of tyrosinase combined with caffeic acid treatment on the yield and recovery rate of goat cheese

[0074] Note 3: Different superscript lowercase letters indicate significant differences among samples in the same column (p < 0.05).

[0075] As shown in Table 3, the tyrosinase treatment concentration has a significant difference in the yield and recovery rate of goat cheese: the yield of goat cheese can be significantly increased by appropriately increasing the tyrosinase treatment concentration. Compared with the control, when the tyrosinase treatment amount is less than 3U / g protein, the yield, corrected yield and total solid recovery rate did not increase significantly; when the tyrosinase treatment amount is 6U / g protein, the goat cheese yield is 0.58% higher than that of the CK group (8.70±0.13%), the corrected yield is 1.24% higher than that of the CK group (9.66±0.06%), and the total solid recovery rate is 6.35% higher than that of the CK group (49.49±0.33%). However, when the tyrosinase treatment amount continues to increase to 10U / g protein, the yield of goat cheese does not increase significantly, and the corrected yield and recovery rate even decrease slightly. It can be seen that the appropriate tyrosinase treatment concentration (6U / g protein) combined with caffeic acid to produce and process goat cheese has a significant beneficial effect on improving cheese yield and recovery rate.

[0076] In addition, there are obvious differences in the sensory properties of goat cheese produced by treating different concentrations of tyrosinase with caffeic acid. Compared with low concentrations, when the tyrosinase treatment concentration is 6U / g protein, the surface of the processed goat cheese is brighter and more lustrous, with a uniform texture, moderate hardness, and delicate tissue. It smells of obvious milk flavor and no goat milk smell. After baking, the cheese is golden yellow, with moderate oil yield and no charring. When the tyrosinase treatment concentration is further increased to 10U / g protein, the sensory properties of the cheese do not change much, but the color brightness is slightly worse than that of the 6U / g protein treatment group.

[0077] Examples 12-13

[0078] This example provides a bio-enzyme treatment method for improving the yield and quality of goat cheese, which is different from Example 1 in that the addition amount of chlorogenic acid is 1 mM and 4 mM respectively. The effects of the treatment methods of Examples 12-13 on the yield and recovery rate of goat cheese are shown in Table 4.

[0079] Table 4 Effects of laccase combined with different concentrations of chlorogenic acid on the yield and recovery of goat cheese

[0080] Note 4: Different superscript lowercase letters indicate significant differences between samples in the same column ( p <0.05).

[0081] As shown in Table 4, the chlorogenic acid treatment concentration has a significant difference in the yield and recovery rate of goat cheese: the yield of goat cheese can be significantly increased by appropriately increasing the chlorogenic acid treatment concentration. Compared with the control, when the chlorogenic acid treatment concentration was 1mM, the yield increased by 1.08% compared with the CK group (8.70±0.13%), and the increase in the corrected yield and total solid recovery rate was not significant; when the chlorogenic acid treatment concentration was 2mM, the goat cheese yield increased by 1.69% compared with the CK group, the corrected yield increased by 0.77% compared with the CK group (9.66±0.06%), and the total solid recovery rate increased by 3.92% compared with the CK group (49.49±0.33%). However, when the chlorogenic acid treatment concentration continued to increase to 4mM, the yield, corrected yield and total solid recovery rate of goat cheese did not change significantly.

[0082] In addition, there are obvious differences in the sensory properties of goat cheese produced by laccase combined with different concentrations of chlorogenic acid. Compared with low concentrations, when the chlorogenic acid treatment concentration is 2mM, the surface of the processed goat cheese is brighter and more lustrous, with a uniform texture, moderate hardness, more elastic chewing, moderate milk flavor, and no obvious goat milk smell. After baking, the surface of the cheese is golden yellow, the oil yield is moderate, and there is no coking phenomenon. When the chlorogenic acid concentration is increased to 4mM, the appearance of the cheese becomes darker and the milk flavor becomes lighter.

[0083] Taking into account the impact on goat cheese yield, recovery rate, sensory quality and other indicators, laccase combined with 2mM concentration of chlorogenic acid was selected to produce and process goat cheese.

[0084] Examples 14-15

[0085] This example provides a bio-enzyme treatment method for improving the yield and quality of goat cheese, which is different from Example 5 in that the addition amount of caffeic acid is 1 mM and 4 mM respectively. The effects of the treatment methods of Examples 14-15 on the yield and recovery rate of goat cheese are shown in Table 5.

[0086] Table 5 Effects of tyrosinase combined with different concentrations of caffeic acid treatment on the yield and recovery rate of goat cheese

[0087] Note 5: Different superscript lowercase letters indicate significant differences between samples in the same column ( p <0.05).

[0088] As shown in Table 5, the concentration of caffeic acid treatment had a significant effect on the yield and recovery rate of goat cheese: the yield of goat cheese could be significantly increased by appropriately increasing the concentration of caffeic acid treatment. Compared with the control, when the concentration of caffeic acid treatment was 1mM, the yield increase was not significant, and the corrected yield and total solid recovery rate increased by 0.80% and 4.10%, respectively; when the concentration of caffeic acid treatment was 2mM, the yield of goat cheese was 0.58% higher than that of the CK group (8.70±0.13%), the corrected yield was 1.24% higher than that of the CK group (9.66±0.06%), and the total solid recovery rate was 6.35% higher than that of the CK group (49.49±0.33%). However, when the concentration of caffeic acid treatment continued to increase to 4mM, the yield, corrected yield and total solid recovery rate of goat cheese did not increase significantly.

[0089] In addition, there are obvious differences in the sensory properties of goat cheese produced by tyrosinase combined with different concentrations of caffeic acid. Compared with low concentrations, when the caffeic acid concentration is 2mM, the surface of the processed goat cheese is brighter and more lustrous, with a uniform texture, moderate hardness, and delicate tissue. It smells of obvious milk flavor and no goat milk smell. After baking, the cheese is golden yellow, with moderate oil yield and no charring. When the caffeic acid concentration is increased to 4mM, the sensory properties of the cheese do not change much.

[0090] Taking into account the impact on goat cheese yield, recovery rate, sensory quality and other indicators, tyrosinase combined with 2mM concentration of caffeic acid was selected to produce and process goat cheese.

[0091] The treatment of biological enzymes combined with phenolic acid also has a significant beneficial effect on the quality maintenance of goat cheese during storage. As shown in Table 6: After ordinary goat cheese is refrigerated at 4℃ for 40-45 days, the total bacterial count, coliform group, and psychrophilic bacteria will exceed the standard, the product surface will be obviously sticky, and abnormal phenomena such as discoloration and taste change will occur; after treatment with laccase combined with chlorogenic acid and tyrosinase combined with caffeic acid, the microbial growth rate is significantly slowed down, and the number of various microorganisms will exceed the standard after 60 days of refrigeration, and the sensory quality will be abnormal. Therefore, the treatment of laccase combined with chlorogenic acid and tyrosinase combined with caffeic acid can extend the shelf life of goat cheese under refrigerated conditions from 40 days to more than 50-55 days. In addition, the treatment of biological enzymes combined with phenolic acid also has a significant slowing effect on the degree of proteolysis and fat oxidation during the storage of goat cheese. After 40 days of vacuum packaging storage at 4℃, compared with CK, the degree of proteolysis of goat cheese produced by laccase combined with chlorogenic acid and tyrosinase combined with caffeic acid was reduced by 0.15 mg·mL -1 and 0.17 mg mL -1 , the degree of fat oxidation decreased by 0.15 mg·g -1 and 0.26 mg·g -1 It can be seen that laccase combined with chlorogenic acid, tyrosinase combined with caffeic acid treatment can effectively slow down the microbial growth, protein hydrolysis and fat oxidation of goat cheese during storage, delay cheese softening, improve cheese storage quality, and extend the shelf life of the product.

[0092] Comparative Example 4

[0093] This comparative example provides a biological enzyme treatment method for improving the yield and quality of goat cheese, which is different from comparative example 1 in that the cheese is wrapped with an edible chitosan-whey protein-mint essential oil composite film and then stored in a vacuum at 4°C.

[0094] Example 16

[0095] This embodiment provides a bio-enzyme treatment method for improving the yield and quality of goat cheese, which is different from Embodiment 1 in that the cheese is wrapped with an edible composite film of chitosan-whey protein-mint essential oil and then stored in a vacuum at 4°C.

[0096] Embodiment 17

[0097] This embodiment provides a bio-enzyme treatment method for improving the yield and quality of goat cheese, which is different from Embodiment 5 in that the cheese is wrapped with an edible composite film of chitosan-whey protein-mint essential oil and then stored in a vacuum at 4°C.

[0098] The effects of the treatment methods of Comparative Example 4 and Examples 16-17 on the quality changes of goat cheese during storage are shown in Table 6. It can be seen that when the goat cheese produced by biological enzyme treatment is wrapped in the chitosan-whey protein-mint essential oil edible composite film for storage and preservation, the total bacterial count, the growth of coliform bacteria, psychrophilic bacteria and other microorganisms, as well as the degree of protein hydrolysis and fat oxidation during refrigeration can be further reduced, so that the cheese maintains better product quality and further extends the shelf life.

[0099] Table 6 Effects of enzyme combined with phenolic acid treatment on quality changes of goat cheese during storage

[0100] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A biological enzyme treatment method for improving the yield and quality of goat cheese, characterized in that: Fresh goat milk is used as raw milk, and biological enzyme and phenolic acid are used for joint treatment, wherein the biological enzyme is laccase or tyrosinase.

2. The bio-enzyme treatment method according to claim 1, characterized in that: The phenolic acids include one or more of chlorogenic acid, caffeic acid and ferulic acid.

3. The bio-enzyme treatment method according to claim 2, characterized in that: The steps include: The raw milk is filtered to remove impurities, heated at 70-75°C for 10-20s, and then cooled to 35-40°C; the pH is adjusted to 6-6.5, and then biological enzymes and phenolic acid are added and incubated for 0.5-1.5h; rennet and calcium chloride are added, and the mixture is allowed to stand for 30-60min and then cut into curds; the curds are allowed to stand for 3-8min, and then heated to 40-50°C within 10-20min and continuously stirred, the whey is discharged, and the mixture is pressed in a mold for 0.5-1.5h; the cheese is blanched in whey at 85-95°C for 20-40min to obtain cheese; after removing moisture from the surface of the cheese, edible salt is evenly applied, and the cheese is stored in a vacuum at 3-5°C.

4. The bio-enzyme treatment method according to claim 3, characterized in that: When the biological enzyme is laccase, the phenolic acid is chlorogenic acid; preferably, the concentration of the laccase is 10-30 U / g, and the addition amount of the chlorogenic acid is 1-4 mM relative to the raw milk.

5. The bio-enzyme treatment method according to claim 3, characterized in that: When the biological enzyme is tyrosinase, the phenolic acid is caffeic acid; preferably, the concentration of the tyrosinase is 1-10 U / g, and the added amount of the caffeic acid is 1-4 mM relative to the raw milk.

6. The bio-enzyme treatment method according to claim 3, characterized in that: The added amount of the rennet is 0.03-0.05 g / L relative to the raw milk.

7. The bio-enzyme treatment method according to claim 3, characterized in that: Relative to the raw milk, the added mass percentage of calcium chloride is 0.005-0.015%; And / or, the amount of edible salt added is 1-3% of the weight of the final cheese product.

8. The bio-enzyme treatment method according to claim 3, characterized in that: Before vacuum storage, the product was wrapped with an edible composite film of chitosan-whey protein-peppermint essential oil.

9. The bio-enzyme treatment method according to claim 3, characterized in that: The yield of the cheese is greater than or equal to 9%.

10. A sheep cheese, characterized in that: The product is prepared by the bio-enzyme treatment method according to any one of claims 1 to 9.

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