Salt-reduced cream cheese and preparation method thereof

Abstract

The invention provides salt-reduced cream cheese and a preparation method thereof, the salt-reduced cream cheese comprises cream cheese, cream, salt and ternary composite particles, and the ternary composite particles are obtained by adding a zein nanoparticle dispersion liquid into a locust bean gum and nOSA starch mixed solution, stirring until the reaction is complete and then freeze-drying. According to the invention, amphiphilic zein-nOSA starch-locust bean gum ternary composite nanoparticles are introduced into a casein-dominated reproduced cream cheese matrix, so that the hot filling viscosity during processing can be remarkably improved, the fat particle size of a salt-reduced cheese product is effectively reduced, a uniform and firm net structure is formed, and the salt-reduced cheese has a good salt-reduced effect. Therefore, the viscoelasticity, the smearing property and the lubricity of the cheese are enhanced, the texture property and the rheological property of the salt-reduced cream cheese are greatly improved, and the stability of the product in the shelf life is improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of food technology, and in particular relates to a salt-reduced cream cheese and a preparation method thereof. BACKGROUND

[0002] Cheese is rich in nutrients such as protein, calcium, and vitamins, and is one of the fastest growing dairy product categories, with a market size of nearly 10 billion yuan. Processed cheese is the main part of the cheese consumption market in China, accounting for more than 90% of cheese consumption. Among them, processed cream cheese (PCC) is widely favored by consumers due to its light flavor, delicate texture, and multi-functional processing characteristics. In particular, its high fat content (usually up to 30-40%) gives it a rich milk fragrance and smooth mouthfeel, making it an ideal raw material in the fields of baking and dipping sauce.

[0003] PCC is a cheese product produced by crushing, heating and melting, and then emulsifying natural cream cheese as the main raw material. In the production process of PCC, emulsifying salts such as citrate and phosphate are often added to chelate insoluble casein in natural cheese to form a uniform emulsion system of processed cheese. However, the combination of high-fat systems and the need for room-temperature storage poses a double challenge to the construction of the emulsion system of PCC: on the one hand, fat globules are prone to coalescence during heat treatment and long-term storage, leading to deterioration of product texture; on the other hand, the addition of emulsifying salts (such as phosphate and citrate) is necessary for the conventional processed cheese process to effectively stabilize the system, but the health risks caused by excessive sodium salt intake have become an important bottleneck restricting the development of the industry. The texture of cream cheese is an important indicator for evaluating its quality, and spreadability is a unique texture indicator of cream cheese in dairy products, which is often used as a fingerprint feature of cream cheese. It not only reflects the hardness and viscosity of the product, but also reflects the uniformity and continuity of the micro-fatty tree network of cream cheese.

[0004] The emulsion stability of PCC is essentially derived from the reactivation of insoluble casein in natural cheese. Insoluble casein in natural cheese is deconstructed into dispersed hydrated casein under the action of melting shear and chelation of emulsifying salts, and covers the surface of dispersed free fat droplets in the form of emulsifiers, thereby forming a stable oil-in-water emulsion. During the subsequent cooling process, part of the dispersed casein matrix forms "flocs", and under the action of static electricity, a uniform and dense emulsion gel is formed. However, when the emulsifying salt content is reduced to 30-50% of the traditional amount, the sudden decrease in sodium ion concentration will result in insufficient soluble casein, which in turn causes instability of the emulsion system. Existing researches have focused on the compounding of hydrophilic colloids or the optimization of homogenization process, but these technical routes are difficult to fundamentally make up for the lack of interfacial emulsifiers caused by salt reduction.

[0005] Therefore, developing a new auxiliary emulsification system to reduce the amount of emulsification salt while maintaining or even improving product stability has become the core issue of current PCC improvement research. SUMMARY

[0006] Therefore, the present application aims to provide a salt-reduced cream cheese and a preparation method thereof, which improves the texture and rheological properties of PCC by adding ZOLPs (a ternary composite particle of zein-nOSA starch-lentil gum).

[0007] To achieve the above-mentioned purposes, the technical scheme of the present application is as follows: In a first aspect, the present application provides a salt-reduced cream cheese, which comprises cream cheese, butter, salt and a ternary composite particle.

[0008] Further, the mass ratio of the cream cheese, butter, salt and ternary composite particle is 30-70:20-30:0.5-1:1-45; preferably 50-70:20-25:0.5:1-5; further preferably 50:22:0.5:1-2. Preferably, the salt-reduced cream cheese further comprises a preservative and water; preferably, the mass ratio of the cream cheese, butter, salt, preservative, ternary composite particle and water is 30-70:20-30:0.5-1:0.1-0.5:1-45:0-30; preferably 50-70:20-25:0.5:0.1:1-5:20-30; further preferably 50:22:0.5:0.1:1-2:20-30.

[0009] Further, the zein nanoparticle dispersion is prepared by an anti-solvent method.

[0010] Further, the concentration of the zein nanoparticle dispersion is 0.1% to 2%, for example, it can be 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.0%; the concentration of nOSA starch in the mixed solution of locust bean gum and nOSA starch is 0.1% to 2%, for example, it can be 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.0%; the concentration of locust bean gum is 0.1% to 1%, for example, it can be 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%.

[0011] Further, the mass ratio of zein nanoparticles, nOSA starch and locust bean gum is 1 to 9:1 to 9:0.25 to 3, for example, it can be 1:9:3, 2:8:2, 3:7:1.75, 1:2:0.5, 4:6:1.5, 5:5:1.25, 6:4:1, 2:1:0.25, 7:3:0.75, 8:2:0.5, 9:1:0.25.

[0012] Further, the cream cheese is obtained by heating, homogenizing, sterilizing, fermenting, centrifuging and cold maturing cow milk.

[0013] Further, the preservative is potassium sorbate.

[0014] In a second aspect, the application provides a preparation method of the salt-reduced cream cheese as described in the first aspect, which comprises the following steps: S1, obtaining a cream cheese by heating, homogenizing, sterilizing, fermenting, centrifuging and cold maturing cow milk; S2, adding a zein nanoparticle dispersion into a mixed solution of locust bean gum and nOSA starch, stirring until the reaction is complete, and freeze-drying to obtain ternary composite particles; S3, shearing and emulsifying the melted butter, salt and ternary composite particles to obtain an emulsified premix; S4, shearing and emulsifying the emulsified premix and softened cream cheese, adjusting the pH to 5.0, sterilizing, degassing and cold maturing to obtain the salt-reduced cream cheese.

[0015] Further, the preparation method comprises the following steps: S1, heating, homogenizing, sterilizing, fermenting, centrifuging milk, and then obtaining cream cheese by cold storage and maturation; S2, adding zein nanoparticle dispersion to a mixed solution of locust bean gum and nOSA starch, stirring until the reaction is complete, and then freeze-drying to obtain ternary composite particles; S3, shearing and emulsifying the melted cream, salt, preservative, ternary composite particles, and water to obtain an emulsified premix; S4, shearing and emulsifying the emulsified premix and softened cream cheese, adjusting the pH to 5.0, sterilizing, degassing, and cold storage and maturation to obtain the reduced-salt cream cheese.

[0016] Further, the temperature for heating and homogenization in step S1 is 60-65°C, the first-stage pressure is 200-500 bar, and the second-stage pressure is 50-100 bar. Preferably, the fermentation is to a pH of 4.8-5.2; further preferably, the starter culture comprises at least one of Lactococcus lactis and Lactococcus cremoris; Preferably, the cold storage and maturation temperature is 2-5°C, and the time is 24-48 h.

[0017] Further, in step S2, the concentration of the zein nanoparticle dispersion is 0.1%-2%, the concentration of nOSA starch in the mixed solution of locust bean gum and nOSA starch is 0.1%-2%, and the concentration of locust bean gum is 0.5%.

[0018] Further, in step S2, the zein nanoparticle dispersion is prepared by an anti-solvent method; preferably, the method for preparing the zein nanoparticle dispersion comprises the following steps: mixing and stirring zein and ethanol until complete dissolution, adjusting the pH to 8.0, then adding water dropwise, and then removing the ethanol by rotary evaporation to obtain the zein nanoparticle dispersion; further preferably, the ethanol is 75% (v / v) ethanol; further preferably, the stirring speed is 500-1000 rpm, for example, it can be 500 rpm, 600 rpm, 700 rpm, 800 rpm, 900 rpm, or 1000 rpm, and the stirring time is 0.5-2 h, for example, it can be 0.5 h, 1 h, 1.5 h, or 2 h.

[0019] Further, in step S2, the mass ratio of zein nanoparticles, nOSA starch, and locust bean gum is 1-9:1-9:0.25-3, for example, it can be 1:9:3, 2:8:2, 3:7:1.75, 1:2:0.5, 4:6:1.5, 5:5:1.25, 6:4:1, 2:1:0.25, 7:3:0.75, 8:2:0.5, or 9:1:0.25.

[0020] Further, in step S2, the freeze-drying method is: pre-freezing for 12 hours in a -80℃ refrigerator, and then vacuum freeze-drying (-40℃) for 48 hours.

[0021] Further, in step S3, the shearing speed of shearing emulsification is 500-2000 rpm, the time is 1-5 minutes, and the temperature is 40-60℃; preferably, the shearing speed of shearing emulsification is 1000 rpm, the time is 2 minutes, and the temperature is 50℃.

[0022] Further, in step S4, the shearing speed of shearing emulsification is 500-2000 rpm, and the time is 5-20 minutes; preferably, the shearing speed of shearing emulsification is 1000 rpm, and the time is 10 minutes. Preferably, in step S4, the sterilization is pasteurization at 70-75℃. Preferably, in step S4, the degassing is vacuum degassing to eliminate air bubbles in the system.

[0023] Preferably, in step S4, the refrigeration ripening temperature is 2-5℃, and the time is 24-48 hours.

[0024] In a third aspect, the application provides application of the zein-nOSA starch-glucomannan ternary composite particles in improving the texture properties and / or rheological properties of the reduced-salt cream cheese or the reduced-salt cream cheese prepared by the preparation method of the second aspect.

[0025] Preferably, the application includes at least one of the following: (1) increasing the filling viscosity of the processed cream cheese; (2) increasing the spread hardness of the processed cream cheese; (3) increasing the shear work of the processed cream cheese; (4) increasing the adhesion of the processed cream cheese; (5) increasing the viscoelastic modulus of the processed cream cheese; (6) reducing the fat particle size of the processed cream cheese; (7) increasing the stability of the processed cream cheese; (8) prolonging the shelf life of the processed cream cheese; (9) improving the mouthfeel of the processed cream cheese.

[0026] Compared with the prior art, the reduced-salt cream cheese and the preparation method thereof have the following advantages: The application introduces the zein-nOSA starch-glucomannan ternary composite nanoparticles with amphiphilic properties into the PCC matrix dominated by casein, which can significantly improve the hot filling viscosity during processing, effectively reduce the fat particle size of the reduced-salt cheese product, form a uniform and firm network structure, thereby enhancing the viscoelasticity, spreadability and lubricity of the cheese, and improving the shelf stability of the product. BRIEF DESCRIPTION OF DRAWINGS

[0027] The accompanying drawings, which form a part of the present application, are used to provide further understanding of the application, and are incorporated herein for explanatory purposes. The illustrative embodiments of the present application and their description serve the purpose of explanations and are not intended to limit the present application. In the drawings: Figure 1 It is a preparation process schematic diagram of the reprocessed cream cheese; Figure 2 It is a texture analysis process schematic diagram of the reprocessed cream cheese; Figure 3 It is a texture analysis result schematic diagram of the product prepared by the reprocessed cream cheese preparation example 1; Figure 4 It is a rheological small deformation experiment result schematic diagram of the product prepared by the reprocessed cream cheese preparation example 1; Figure 5 It is a rheological large deformation experiment result schematic diagram of the product prepared by the reprocessed cream cheese preparation example 1; Figure 6 It is a particle size determination result schematic diagram of the product prepared by the reprocessed cream cheese preparation example 1; Figure 7 It is a stability analysis result schematic diagram of the product prepared by the reprocessed cream cheese preparation example 1; Figure 8 It is a schematic diagram of the mechanism of ZOLPs improving the spreadability of reduced-salt PCC; Figure 9 It is a texture analysis result schematic diagram of the product prepared by the reprocessed cream cheese preparation example 2; Figure 10 It is a rheological small deformation experiment result schematic diagram of the product prepared by the reprocessed cream cheese preparation example 2; Figure 11 It is a rheological large deformation experiment result schematic diagram of the product prepared by the reprocessed cream cheese preparation example 2; Figure 12 It is a stability analysis result schematic diagram of the product prepared by the reprocessed cream cheese preparation example 2; Figure 13 It is a mouth tribology test result schematic diagram of the product prepared by the reprocessed cream cheese preparation example 2; Figure 14 It is a laser confocal scanning result schematic diagram of the product prepared by the reprocessed cream cheese preparation example 2; Figure 15The scanning electron microscope results of the product prepared in Example 2 for reconstituted cream cheese are shown in the schematic diagram. DETAILED DESCRIPTION

[0028] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0029] The experimental results in the present embodiment are expressed as mean ± standard deviation (Mean ± SD), and the data and graphs are processed using Excel and Origin software, and the experiments are measured in triplicate. SPSS 28.0 statistical software is used for factor variance analysis, and the differences between different treatment groups are analyzed by Duncan's new multiple range method, and the significant level is set as P<0.05.

[0030] The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0031] The terms in the embodiments are as follows: ZPs refers to zein particles; ZOPs refers to zein-nOSA starch binary composite particles; ZOLPs refers to zein-nOSA starch-llocandamendola gum ternary composite nanoparticles.

[0032] Example 1 Preparation of zein nanoparticle dispersion 4g of zein was weighed and dissolved in 250mL of 75% (v / v) ethanol, and a magnetic stirrer was used to stir at a speed of 600rpm for 1h to fully dissolve the zein. A 1M NaOH standard solution was used to adjust the zein solution to pH 8.0. Then under continuous stirring, zein nanoparticles were formed by dropwise addition to 200mL of deionized water by anti-solvent method. The ethanol in the system was removed by rotary evaporation, and the system was concentrated to 200mL to obtain a zein nanoparticle dispersion, wherein the mass concentration of zein colloidal particles was 2.0% (w / v).

[0033] Example 2 Preparation of binary composite particles Preparation of zein nanoparticles: 4 g of zein was dissolved in 250 mL of 75% (v / v) ethanol, and the zein was fully dissolved by stirring at 600 rpm for 1 h using a magnetic stirrer. The zein was then adjusted to pH 8.0 using a 1 M NaOH standard solution. Zein nanoparticles were then formed by dropwise addition to 200 mL of deionized water under continuous stirring by an anti-solvent method. The ethanol in the system was removed by rotary evaporation, and the system was concentrated to 200 mL to obtain a zein nanoparticle dispersion. The mass concentration of the zein colloidal particles in the final solution system was 2.0% (w / v).

[0034] 4 g of nOSA starch was dissolved in 180 mL of deionized water, and the nOSA starch was adjusted to pH 8.0 using a 1 M NaOH standard solution. The nOSA starch solution was diluted to 200 mL with deionized water to obtain a nOSA starch solution with a concentration of 2.0% (w / v). Different proportions of the zein nanoparticle dispersion prepared in the preparation example were added to the obtained nOSA starch solution to obtain a mass ratio of zein to nOSA starch of 9:1. The nOSA starch and zein were fully reacted to form binary composite particles ZOPs by stirring for 1 h.

[0035] Example 3 Preparation of ternary composite particles 4 g of nOSA starch was dissolved in 180 mL of deionized water, and 1 g of locust bean gum (LBG) was added to the system. The nOSA starch was adjusted to pH 8.0 using a 1 M NaOH standard solution, and the system was diluted to 200 mL with deionized water to obtain a mixed solution of locust bean gum and nOSA starch. The concentration of nOSA starch in the mixed solution was 2.0% (w / v), and the concentration of locust bean gum was 0.5% (w / v). Different proportions of the zein nanoparticle dispersion prepared in the preparation example were added to the mixed solution of locust bean gum and nOSA starch by a reverse titration method to obtain a mass ratio of zein to nOSA starch of 1:9, 1:2, 2:1, and 9:1, respectively. The zein, nOSA starch, and locust bean gum were fully reacted to form ternary composite particles by stirring for 1 h, and the ternary composite particles were labeled as ZOLPs1:9, ZOLPs1:2, ZOLPs2:1, and ZOLPs9:1, respectively, according to the mass ratio of zein to nOSA starch.

[0036] Example 4 Preparation of raw cream cheese The standardized fresh milk was heated to 60-65°C and homogenized at 200 / 50 bar. After homogenization, the emulsion was pasteurized at 75°C for 15 s and cooled to 30-32°C. The emulsion was inoculated with starter culture at 32°C. The starter culture used in this example was a commercially available product comprising Lactococcus lactis and Lactococcus cremoris, and the fermentation was carried out until the pH reached 4.8-5.2. After the fermentation reached the target acidity, the emulsion formed curd, and then centrifugal bag filtration was performed to remove whey, to obtain the desired cheese curd. The cheese curd was packaged and sealed, and then ripened at 2-5°C for 24 h to fully mature the flavor, to obtain the final product of the original cream cheese. The protein content of the final product of the original cream cheese was 11.9%, and the fat content was 16.0%.

[0037] Example 5 Preparation of the reprocessed cream cheese As shown in Figure 1 , the original cream cheese prepared in the preparation of the original cream cheese was first placed in a shearing thermomix emulsification heater, and preheated and softened at a temperature of 40-50°C to make the texture uniform.

[0038] Secondly, the zein nanoparticles, ZOPs and ZOLPs (ZOLPs 9:1) composite nanoparticles were weighed according to the formula in Table 1, and the melted anhydrous butter, salt, potassium sorbate, emulsifying salt (sodium citrate and sodium hexametaphosphate), deionized water and other ingredients were added at 50°C, and high shear emulsification was performed (shear speed 1,000 rpm, shear time 2 min) to form an emulsified premix.

[0039] Subsequently, the premix was slowly added to the softened original cream cheese, and emulsified for 10 min at a high shear speed to ensure that the components were fully mixed and homogenized. The pH was measured and adjusted to 5.0 using a 1 mol / L HC1 standard solution.

[0040] The temperature was controlled at 70-75°C during the emulsification process to complete pasteurization. Then, the uniformly mixed PCC slurry was subjected to vacuum degassing treatment to eliminate the gas bubbles present in the system.

[0041] After degassing, the PCC slurry was quickly cooled to 4°C and ripened at this temperature for 24-48 h to form a stable emulsion gel structure, and finally a PCC product with delicate texture, soft flavor and stable structure was obtained.

[0042] Table 1 Formulation of PCC with different amounts of ZOLPs added to cheese

[0043] Performance test 1 Viscosity test of the reprocessed cream cheese Immediately after the end of the pasteurization of the cheese, 100 g of cheese sample was weighed for viscosity test. A Brookfield LV viscometer was used with spindle S64, rotation speed of 10 rpm, test time of 1 min, and the change of real-time viscosity was recorded.

[0044] The results are shown in Table 2. The hot filling viscosity of the cheese samples in different groups was in the range of 1579-7223 cp, which belonged to the normal and low filling viscosity range. The viscosity data showed that the ternary nanoparticle ZOLPs could replace emulsifying salt to improve the semi-finished product viscosity during hot filling of cheese, which was helpful for the product forming after filling. When the butter cheese was added at 50% and 70%, the hot filling viscosity was in the ideal filling viscosity range, which could meet the requirements of filling viscosity limit and minimum forming viscosity.

[0045] Table 2 Effect of ZOLPs on the hot filling viscosity of PCC

[0046] Mean ± SD, different letters a-e in the same row indicate significant differences.

[0047] Performance test 2 Texture analysis of reconstituted butter cheese According to the texture profile analysis (TPA) method of Brighenti, a TTC Spreadability Rig (HDP / SR) diamond type kit was used as the texture probe (as shown in Figure 2 The spreadability and stickiness of the sample were tested. The distance of 25 mm above the bottom of the test groove was used as the starting point of the test, the compression distance was 23 mm, the down pressure speed was 3.0 mm / s, the lifting speed was 10.0 mm / s, and the probe returned to the starting point. The reaction force of the probe on the sample was used as the vertical coordinate, and the down pressure time was used as the horizontal coordinate for data analysis. The sample was added to the sample groove, smoothed, and placed in 4°C for temperature balance, and then measured immediately after 1 h.

[0048] The TPA texture profile is shown in Figure 3 At the cheese content of 30%, 50%, and 70% addition, all PCC samples showed certain spreadability. With the down pressure of the cone-shaped probe, the maximum value of the reaction force, i.e. the hardness of the spread, indicated the softness and hardness of the cheese. The area enclosed by the force curve and the time axis during the down pressure process was the shear work, which indicated the size of the energy required for the cheese to spread. During the return process of the probe, the absolute value of the reaction force reached another maximum value, i.e. the adhesion, and the area enclosed by the time axis and the force curve was the adhesion work.

[0049] According to Figure 3The texture profile analysis can be used to calculate the texture evaluation indexes in Table 3. From the spread hardness, the cheese samples added with ZOLPs are significantly higher than the emulsified salt group cheese samples, and with the decrease of cheese content, the hardness shows a gradually decreasing trend. The shear work can reflect the work done in one spreading process. As shown in Table 3, the shear work of cheese content of 30% and 50% is significantly lower than that of 70% cheese content, which may be related to the soft texture and loose structure. The adhesion data shows that for samples with different cheese contents, the addition of ZOLPs can significantly reduce the adhesion size. At the same time, the adhesion work of different groups of cheese samples is in the range of-228~ -764 g·s, indicating that the adhesion of the sample is low, the adhesion is weak, and the texture of the cheese is delicate. In actual processing, it is necessary to balance the hardness and shear work, so that the butter cheese has good spreadability under certain hardness conditions.

[0050] Table 3 Effect of ZOLPs on the texture of PCC

[0051] Mean ± SD, the same row marked with different letters a-f, indicating significant difference.

[0052] Performance test 3 Rheological properties of reprocessed butter cheese Rheological small deformation experiment: referring to the method of Ningtyas et al. for determining the rheology of cheese, the rheometer was used to determine the changes of G' and G'' of PCC. The sample was taken out from the refrigerator and placed at room temperature for 30 min. The sample was made into a thin piece with a clamp diameter of 60 mm and a gap of 1 mm, and the temperature was controlled by a Peltier plate system HAAKE VTiQ-T. The temperature oscillation scanning test was carried out. Cover to prevent evaporation, angular frequency 1 Hz, stress 1 Pa (verified to be in the linear viscoelastic region). Set the temperature rising speed to 2℃ / min, the temperature range to 20-80℃, and collect data every 45s.

[0053] As shown in Figure 4 , for butter cheese with different cheese contents, the addition of ternary composite particles significantly increases the G' and G'' of cheese. Among them, under the conditions of cheese content of 50% and 70%, G' and G'' are significantly higher than those of other groups of samples, indicating that they have stronger viscoelasticity and more obvious bonding between protein molecules. When the temperature rises to 40℃, since it is higher than the melting point of anhydrous butter, the G' and G'' of cheese reach the minimum value, indicating that the cheese sample has obvious softening. With the further increase of temperature, the sample added with ZOLPs does not change significantly, while the sample without ZOLPs has a significant increase in viscoelasticity when the temperature exceeds 60℃, indicating that the addition of ZOLPs helps to improve the heat resistance of PCC, and its structure is less affected by temperature, more firm and stable.

[0054] Rheology large deformation experiment: according to the method of Safarik et al., the sample was taken out from the refrigerator and placed at room temperature for 30 min, the sample was made into a thin piece with a clamp diameter of 60 mm and a gap of 1 mm, and the temperature was controlled by a Peltier plate system HAAKE VTiQ-T, and stress scanning was performed to monitor the changes of G', G'' of cheese rheology parameters.

[0055] As shown in Figure 5 , the results of stress scanning show that the G' of cheese samples with 50%, 70% cheese content and adding ternary particles is significantly higher than that of other group samples, indicating that it has more solid properties. At the same time, for samples with 50%, 70% cheese content, the mutation value of viscoelastic modulus (G' and G'') is significantly higher than that of other group samples. And this mutation value is directly related to the structural stability of cheese samples, the lower the mutation value, the more unstable the structure, therefore, the 50%, 70% cheese samples added with ZOLPs have relatively stable structure and are not easy to be damaged by external force.

[0056] Therefore, combined with the previous basic data, in the follow-up experiment, 50% cheese addition amount is selected as the model for further verification.

[0057] Performance test 4 determination of fat particle size of reprocessed cream cheese A certain amount of PCC sample was dissolved in deionized water, 4% SDS solution was added to make the cheese structure collapse, and the fat particles were dispersed, and Malvern Zetasizer Nano-ZS90 was used for detection. The refractive index of continuous phase water at 25°C is 1.330, the viscosity is 0.8872 mPa·s, and the dielectric constant is 78.5; the refractive index of dispersed phase anhydrous butter is 1.50, and the absorption rate is 0.001. The program is set to balance for 120 s before sample particle size test, and the general mode is selected for particle size analysis, the particle size sample tank is used, and the particle size of the dispersed phase is obtained. Each sample is tested in triplicate, and each parallel is measured three times.

[0058] As shown in Figure 6 , the addition of ternary composite nanoparticles ZOLPs can significantly reduce the fat particle size of cheese, indicating that within the range of 30-70% cheese content, ZOLPs can effectively enhance the emulsification effect of cream cheese system and promote the dispersion of fat particles. Therefore, the higher emulsification of ZOLPs can replace the use of emulsifying salt in cheese system, thereby reducing the sodium content in cheese products, and providing a basis for the development of salt-reduced cheese.

[0059] Performance test 5 stability analysis of reprocessed cream cheese The stability of the prepared PCC was analyzed by centrifugal acceleration using a LUMISizer stability analyzer. The refrigerated sample was equilibrated at room temperature for 30 min, then a suitable amount of cheese sample was taken with a needle and added to the sample cell, then symmetrically placed in the designated sample slot, set the temperature to 25°C, centrifugal speed to 3000 rpm, scan once every 10 s, scan 255 profile lines, run for 3600 s, light factor 1.00, wavelength 865 nm, and measure the profile line of the change in transmitted light with time.

[0060] As shown in Figure 7 , the prepared cheese samples all showed different degrees of change in transmitted light, which was manifested as an increase in the transmitted light at the top of the centrifugal tube, indicating that the cheese samples had different degrees of water separation. First, by adding ternary composite particles ZOLPs, the migration and separation of water can be significantly reduced, the change in transmitted light is reduced, and the shelf life stability of PCC is improved. Second, as the cheese content decreases, the transmitted light also increases significantly, which is related to the ability of casein to improve hydration.

[0061] Example 6 Preparation of reduced-salt processed cheese according to preparation example 2 According to the preparation method of the prepared reduced-salt processed cheese according to preparation example 1, the reduced-salt processed cheese was prepared according to the formula in Table 4.

[0062] Table 4 Formulation of zein particles (ZPs), zein-nOSA starch binary composite particles (ZOPs), and ZOLPs (ZOLPs 9:1) in reduced-salt PCC

[0063] Referring to performance tests 1-5, the product prepared in Example 2 was subjected to viscosity testing, texture analysis, rheological property analysis, particle size determination, stability analysis, microstructure observation, and oral tribology testing, respectively.

[0064] The viscosity test results are shown in Table 5. The viscosity of the cheese hot-filled with ZOPs and ZOLPs particles was significantly higher than that of the other groups, indicating that ZOPs and ZOLPs particles had a significant effect on the improvement of the viscosity of the cheese hot-filled. The hot-filled viscosity of the processed cheese with only LBG, or Zein, or nOSA starch was in the range of 1621-3793 cp, which was significantly lower than that of the cheese sample with binary ZOPs or ternary ZOLPs nanoparticles. Therefore, the addition of ZOPs and ZOLPs particles can meet the processing applicability requirements of PCC.

[0065] Table 5 Effect of ZPs, ZOPs, and ZOLPs particles on the hot-filled viscosity of reduced-salt PCC

[0066] Mean ± SD, with different letters ae in the same row indicating significant differences.

[0067] Texture analysis results are as follows Figure 9 As shown in Table 6, the 50% cheese content samples prepared by adding mono-, binary, and ternary particles met the basic characteristics of cream cheese, possessing a certain degree of hardness and spreadability. Table 6 also shows that there were no significant differences in spreadability, shear work, and adhesiveness between cheese samples prepared with ZOPs and ZOLPs, indicating that at a cheese content of 50%, binary and ternary composite particles promoted the formation of a stable PCC structure, resulting in similar cheese textures. Meanwhile, single particles, such as LBG, ZPs, or nOSA starch, resulted in lower hardness and adhesiveness, indicating a thinner texture, making it impossible to achieve the ideal cream cheese texture and state with a single particle. Therefore, ZOPs and ZOLPs particles are effective in promoting the formation of PCC texture.

[0068] Table 6. Effects of ZPs, ZOPs, and ZOLPs on the textural properties of reduced-salt PCC

[0069] Mean ± SD, with different letters ae in the same row indicating significant differences.

[0070] The rheological property analysis results are as follows Figures 10-11 As shown, the G′ values ​​of different cream cheeses are significantly greater than G′′, indicating that the samples conform to typical cheese gel characteristics, that is, they tend to be elastic solids, which is beneficial for maintaining the shape and three-dimensional network structure of the cheese. At the same time, as the temperature gradually increases, the G′ of the cream cheeses all show a trend of decreasing first, and the lowest G′ values ​​all appear around 40℃.

[0071] As the temperature further increased, the G′ value remained low in cream cheese with added ternary particles and cream cheese with added nOSA starch or Zein alone, while the G′ value gradually increased with the addition of LBG, binary particles, and G′, indicating that the structure underwent some degree of damage under high-temperature conditions. This result further verifies that the use of LBG and ZOPs alone has poor emulsification stability and certain limitations. The temperature scanning results show that the addition of ternary nanoparticles ZOLPs to PCC significantly improved the structural stability and heat resistance of the cheese.

[0072] With increasing shear stress, the G' and G'' values ​​of most cream cheeses did not change significantly. However, when the stress exceeded a certain value, G' and G'' suddenly decreased, indicating that the cheese's structure began to break down. Figure 11It can be seen that the stress values ​​of the mutations in G' and G'' of cheese with added ternary particles are significantly greater than those of other cheeses, indicating that the cheese with added ternary particles has the most stable structure. For the ZOLPs sample, its elastic modulus shows a trend of first increasing and then decreasing with increasing temperature. This change reflects that the interaction force between protein molecules inside the cheese is strengthened due to the increase in temperature, thus increasing the elastic modulus, but its viscous modulus does not increase significantly.

[0073] Furthermore, a comparison between ZOLPs and ZOPs shows that the addition of LBG significantly increases the G' and G'' values ​​of PCC, indicating that LBG enhances emulsion stability by improving the interfacial adsorption of ZOPs, thus forming a polymer with stronger viscoelasticity.

[0074] The particle size determination results are shown in Table 7. With the addition of ZPs, ZOPs, and ZOLPs, the particle size of cheese fat showed a significant decreasing trend. For cheese samples with added ZOLPs ternary particles, the particle size was in the small range of 2-3 μm. The smaller particle size is beneficial to the uniform distribution of protein and fat in cheese, thereby forming a uniform three-dimensional network structure and increasing the stability of the cheese structure.

[0075] Table 7. Effects of ZPs, ZOPs, and ZOLPs on the particle size of reduced-salt PCC

[0076] Mean ± SD, with different letters ae in the same row indicating significant differences.

[0077] Stability analysis such as Figure 12 As shown, when the cheese content is 50%, the transmitted light changes of the reduced-salt cheese samples with added ZOLPs and ZOPs are small, while the reduced-salt cheese samples with added LBG, ZPs and nOSA starch alone show obvious changes in transmitted light at the top, proving that the samples may have significant water separation during the shelf life, affecting the stability of the product's shelf life.

[0078] Determination of the microstructure of processed cream cheese: Laser confocal scanning observation: The microstructure of cheese was observed using a confocal laser scanning microscope. Cheese samples were stained with a mixed staining solution containing Nile Blue (0.1%) and Nile Red (0.1%). Nile Blue stained ZOLPs (helium-neon laser, excitation wavelength 633 nm), and Nile Red stained the oil phase (anhydrous butter) (argon laser, excitation wavelength 488 nm). The cheese samples were then placed in the groove of a concave microscope slide and gently covered with a coverslip before observation.

[0079] Scanning electron microscopy observation: TM40000 Plus desktop scanning electron microscope (SEM) was used to observe the microstructure of PCC. According to the method of Macdougall et al., after rapid freezing in liquid nitrogen, cooling and sublimation drying, the freeze-dried cheese was cut into 1 mm slices, fixed on the cylindrical sample table using conductive double-sided tape, then vacuumized and gold sprayed; the prepared sample was placed into the SEM, and the micro-morphology was observed at a voltage of 15 kV using Conduct (H) and backscattered electron imaging (BSE), with a magnification of 3000.

[0080] As shown in Figure 14 and 15 , it was detected that the fat phase in the three-dimensional network structure of butter cheese showed a dendritic morphology. These structures can effectively reduce the interfacial tension and balance the amphiphilic characteristics of fat globules and ZOLPs particles with different sizes, and can form micron-sized oil droplets under limited shear action. The size ratio of fat globules and ZOLPs particles is close to 10:1, which meets the size characteristics of Pickering emulsion. Based on the above experimental results, it can be inferred that ZOLPs construct a branched interconnected network at the microscale by physical contact steric hindrance and bridging effect of polysaccharide nOSA starch and LBG, which enhances the viscoelasticity and structural compactness of the system (as shown in Figure 8 ), and gives butter cheese its unique spreadability.

[0081] Oral tribology test: A pressure-controlled rheometer was used to determine the tribological properties of the simulated oral salt-reduced cheese samples. 2.0 g of cheese sample was placed in a three-plate ball carrier and evenly coated on the PDMS rubber plate to start the test. The sliding rate was set to 0.01-1000 mm / s, the stress was 3.0 N, and the temperature was 25℃.

[0082] As shown in Figure 13 , the friction coefficients of the 5 groups of salt-reduced cheese samples showed a trend of first increasing and then decreasing, which is consistent with the characteristics of butter cheese spreadability. When the sliding rate is greater than 0.1 mm / s and less than 2 mm / s, the protein and fat in the contact area of the cheese continuously enter the gap, causing the friction coefficient to gradually increase. Within the sliding rate range of 2-20 mm / s, the friction coefficients of different cheese samples have significant differences. When the sliding rate is greater than 100 mm / s, the fat gradually aggregates, increasing the fat lubricating layer and gradually reducing the friction coefficient. The friction coefficient at a sliding rate of 5 mm / s was extracted for comparison, and the friction coefficients of the 5 groups of samples were sorted as ZOLPs < ZOPs ≤ LBG ≤ nOSA starch < ZPs (as shown in Table 8).

[0083] Table 8 Effect of ZPs, ZOPs and ZOLPs on the friction coefficient of reduced-salt PCC

[0084] Mean ± SD, different letters a-e in the same row indicate significant differences.

[0085] In addition, the friction coefficient of reduced-salt cheese added with ZOLPs and ZOPs was significantly lower than that of other group samples, indicating that the lubricity of the surface was stronger, which was related to the smaller fat globule size. Uniform and smaller fat globule particles help the friction deformation of fat particles. Therefore, improving the emulsification performance by ZOPs or ZOLPs composite nanoparticles and controlling the particle size of cheese help to improve the sensory properties such as delicacy of the product.

[0086] In summary, the application verifies the application effect of ZOLPs in reduced-salt PCC and the influence of unary, binary and ternary composite nanoparticles on reduced-salt PCC, determines the viscosity during PCC processing, product texture properties, rheological properties, shelf life stability, particle size, microstructure and tribology, and draws the following conclusions: (1) ZOLPs in PCC with different cheese contents can significantly improve the hot filling viscosity during processing, effectively reduce the fat particle size of reduced-salt cheese products, form a uniform and firm network structure, thereby enhancing the viscoelasticity, spreadability and lubricity of cheese, and improving the shelf life stability of the product.

[0087] (2) The reduced-salt PCCs prepared by ZPs, ZOPs and ZOLPs have obvious differences in physicochemical characteristics. Among them, the addition of ZOLPs conforms to the typical cream cheese texture characteristics, the viscoelasticity is appropriate, and the microstructure is relatively uniform. ZOPs mainly differ from ZOLPs in viscoelastic modulus and microstructure, and cheese added with LBG, Zein or nOSA starch alone does not have typical cream cheese characteristics.

[0088] (3) Mechanism of ZOLPs composite particles in improving the spreadability of reduced-salt PCC. PCC prepared by adding ZOLPS composite particles has good spreadability. In the cream cheese system, the non-polar lipophilic end of Zein and nOSA fully contacts and combines with fat during homogenization, and the original Zein-nOSA composite particle structure is destroyed. It adheres to the oil interface on the surface of the fat globule according to the principle of similar polarity and similar affinity, forming a chain-like wrapping on the surface of the fat globule, thereby giving good spreadability.

[0089] The above described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments of the present application, other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present application.

Claims

1. A low-salt cream cheese, characterized in that: The reduced-salt cream cheese includes cream cheese, cream, salt, and ternary composite particles. The ternary composite particles are obtained by adding a dispersion of zein nanoparticles to a mixed solution of locust bean gum and nOSA starch, stirring until the reaction is complete, and then freeze-drying.

2. The low-sodium cream cheese according to claim 1, characterized in that: The mass ratio of the cream cheese, cream, salt, and ternary composite particles is 30~70:20~30:0.5~1:1~45.

3. The low-sodium cream cheese according to claim 1, characterized in that: The mass ratio of the zein nanoparticles, nOSA starch, and locust bean gum is 1~9:1~9:0.25~3.

4. The low-sodium cream cheese according to claim 1, characterized in that: The cream cheese is obtained by heating, homogenizing, sterilizing, fermenting, and centrifuging milk, followed by refrigeration and maturation.

5. The application of ternary composite particles of zein-nOSA starch-locust bean gum in improving the textural properties and / or rheological properties and / or stability of processed cream cheese as described in any one of claims 1-3; Preferably, the application includes at least one of the following: (1) Increase the filling viscosity of processed cream cheese; (2) Improve the spreadability of processed cream cheese; (3) Improve the shearing work of processed cream cheese; (4) Improve the adhesiveness of processed cream cheese; (5) Increase the viscoelastic modulus of processed cream cheese; (6) Reduce the fat particle size of processed cream cheese; (7) Improve the stability of processed cream cheese; (8) Extend the shelf life of processed cream cheese; (9) Improves the texture of processed cream cheese.

6. The application according to claim 5, characterized in that, The method for preparing the reduced-salt cream cheese includes the following steps: S1. After heating, homogenizing, sterilizing, fermenting, and centrifuging the milk, the cream cheese is obtained by refrigerating and maturing it. S2. Add the corn glycerin nanoparticle dispersion to the mixed solution of locust bean gum and nOSA starch, stir until the reaction is complete, and freeze dry to obtain ternary composite particles. S3. The melted butter, salt and ternary composite particles are sheared and emulsified to obtain an emulsion premix; S4. The emulsified premix and softened cream cheese are sheared and emulsified, the pH is adjusted to 5.0, sterilized, degassed, and refrigerated to mature, thus obtaining the reduced-salt cream cheese.

7. The application according to claim 6, characterized in that, In step S1, the heating and homogenization temperature is 60~65℃, the first-stage pressure is 200~500 bar, and the second-stage pressure is 50~100 bar; Preferably, the fermentation is carried out until the pH is 4.8-5.2; Preferably, the refrigeration and maturation temperature is 2~5℃ and the time is 24~48h.

8. The application according to claim 6, characterized in that, In step S2, the concentration of the zein nanoparticle dispersion is 0.1%~2%, and the concentration of nOSA starch in the mixed solution of locust bean gum and nOSA starch is 0.1%~2%, and the concentration of locust bean gum is 0.1%~1%. Preferably, the preparation method of the zein nanoparticle dispersion includes the following steps: mixing zein with ethanol and stirring until completely dissolved, adjusting the pH to 8.0, adding it dropwise to water, then removing the ethanol by rotary evaporation, and concentrating to obtain the zein nanoparticle dispersion.

9. The application according to claim 6, characterized in that, In step S3, the shearing rate of the shear emulsification is 500~2000 rpm, the time is 1~5 min, and the temperature is 40~60℃.

10. The application according to claim 6, characterized in that, In step S4, the shear rate for shear emulsification is 500~2000 rpm, and the time is 5~20 min; Preferably, the refrigeration and maturation temperature is 2~5℃ and the time is 24~48h.

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