Preparation method of calcium fortified plant oil body self-aggregates based on charge response

Abstract

The application discloses a preparation method of a calcium fortified plant oil body self-aggregate based on charge response, and the calcium fortified plant oil body self-aggregate based on charge response is prepared by the following steps: obtaining soybean oil bodies through mild / deep purification, suspending milk calcium powder in the oil bodies, stirring and uniformly dispersing, and adjusting the pH of the system to 4.5 and 5.0 respectively. The main method comprises the following steps: (1) extracting soybean oil bodies through mild / deep centrifugation; (2) adsorbing calcium through oil bodies, and uniformly dispersing milk calcium in the oil bodies; and (3) based on the charge response characteristic, preparing the calcium fortified plant oil body self-aggregate based on charge response by reducing the pH. The calcium fortified plant oil body self-aggregate based on charge response prepared by the application has the following advantages: based on the charge response, no additional polysaccharide is needed, and high viscosity can be obtained only by adjusting the acidic condition; the milk calcium is uniformly dispersed in the soybean oil body lipid self-aggregate and serves as a calcium fortified preparation; and the calcium fortified plant oil body self-aggregate based on charge response can be applied to salad dressing and serves as a fat substitute to endow food with good thixotropic recovery.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of food colloid and food industry, and particularly relates to a preparation method of calcium fortified plant oil body self-aggregates based on charge response. BACKGROUND

[0002] Soybean is an important oil crop in China and an important raw material for plant-based food, providing high-quality protein and oil for human diet. Soybean oil body, as a natural subcellular organelle in soybean, stores a variety of unsaturated fatty acids, fat-soluble vitamins, soybean isoflavones and other bioactive substances in soybean, has strong physical and chemical stability, and is a natural emulsifier for improving the stability of food raw materials. At the same time, it is more healthy and economical than general emulsifiers. Soybean oil body is in the form of a small spherical droplet with a diameter of 0.5 to 2 μm, and its internal structure is mainly composed of liquid triacylglycerol, and its surface is covered with a biological membrane composed of a single layer of phospholipid and endogenous protein. It is widely used in the production, processing and development of foods such as thousand island sauce, edible film, tofu and soy-based whipped cream.

[0003] The process of oil body extraction begins with the immersion of seeds in an aqueous medium. Subsequent mechanical agitation or pressing operations are performed to disrupt the cell wall and release the intracellular contents. The extraction process forms an emulsion that retains exogenous storage proteins and cell wall components that significantly affect the properties of the emulsion. For purified oil body emulsions, these exogenous materials can be effectively removed by multiple centrifugal washes. The introduction of oil bodies can save energy-intensive emulsification processes and eliminate the need for emulsifiers. In addition, the naturally occurring protein-phospholipid interface helps to protect the oil from oxidation, thereby avoiding the need for antioxidants. Therefore, how to effectively regulate the interaction between lipids and protein systems and then adjust the physicochemical properties of natural emulsions becomes a key to their application.

[0004] The rheological properties of sauce food are very important and play a decisive role in the acceptance of consumers. Traditional sauce foods such as salad dressing have a high oil content of about 30%-50%. With the increasing attention of consumers to "high-calorie, high-fat, high-cholesterol" foods, soybean plant oil bodies, due to their specific structural composition and rich nutritional value, have become a research hotspot as a fat substitute in high-fat foods in recent years. SUMMARY

[0005] The application aims to provide a calcium fortified plant oil body self-aggregate preparation method based on charge response, obtain soybean oil bodies through light / depth purification, add milk calcium to be uniformly adsorbed at the interface of the oil bodies, adjust pH to obtain calcium fortified plant oil body self-aggregate, the raw material is green and natural, the emulsion is simple to prepare and low in energy consumption, no additional polysaccharide is needed, the calcium is rich in nutrition, the thixotropic recovery is good, and the calcium can be applied to salad dressing and other foods.

[0006] The application is realized by the following technical scheme:

[0007] A calcium fortified plant oil body self-aggregate preparation method based on charge response comprises the following steps:

[0008] (1) Light / depth purification of soybean oil bodies: soybean is mixed with 0.1M NaHCO3 solution at a mass ratio of 1:7, soaked at 4℃ for 18h, stirred for 6min by a cell wall breaking machine, adjusted to pH 11, stirred at 50℃ water bath for 2h, filtered to obtain an oil body suspension, and prepared by centrifugation at 4℃.

[0009] (2) Oil body adsorption of milk calcium: the light / depth purified soybean oil bodies are uniformly mixed with deionized water, 150mg / 100ml of milk calcium powder is added to the oil body emulsion, and the sample is sheared to uniformly disperse the milk calcium;

[0010] (3) Charge response plant oil body self-aggregate: the pH of the oil body emulsion is adjusted by using a hydrochloric acid solution, so that the originally strong flowability of the emulsion is instantaneously changed into high viscosity cream.

[0011] Further, in step (1), the centrifugal speed is 5000rpm and the centrifugal time is 15min under light purification conditions; the centrifugal speed is 10000rpm and the centrifugal time is 30min under depth purification conditions. Low speed and short time centrifugation can obtain more exogenous proteins, and the system is a mixture of soybean oil bodies and exogenous proteins; high speed and long time centrifugation can obtain high-purity soybean oil bodies, and the system is mainly composed of endogenous proteins and lipids in the oil bodies.

[0012] Further, in step (2), the light / depth purified soybean oil bodies are mixed with deionized water at a volume ratio of 1:1 to prepare an oil body emulsion. When the water content is too low (<1:1), the viscosity of the emulsion is too high, the uniformity and dispersibility of the milk calcium in the system are poor; when the water content is too high (>1:1), the distance between the particles in the emulsion components is far, the interaction between the particles is weak, effective crosslinking cannot be formed, the system has low viscosity, and the formation of the soybean oil body lipid self-aggregate is affected.

[0013] Furthermore, in step (2), milk calcium powder is added to the grease emulsion and dispersed at a shear rate of 8000 rpm. The use of a shear dispersion device can stably adsorb milk calcium onto the interface of the grease body based on the system energy, thereby improving the dispersibility of milk calcium. If the shear rate is too low (<8000 rpm), the milk calcium is unevenly dispersed, the system is unstable, and precipitation is prone to occur; if the shear rate is too high (>8000 rpm), the grease emulsion particles produced are too small and are also prone to demulsification, which in turn causes milk calcium precipitation and system instability.

[0014] Furthermore, in step (3), hydrochloric acid solution is used to adjust the pH of the lightly purified soybean grease body emulsion loaded with milk calcium to 4.5, and the pH of the deeply purified soybean grease body emulsion loaded with milk calcium to 5.0. Lightly purified soybean grease bodies contain a high content of exogenous proteins (mainly glycinin and β-conglycinin), and their isoelectric point is close to that of soy protein isolate at around 4.5, and they also have the highest viscosity; deeply purified soybean grease bodies mainly contain endogenous proteins (oleosin, caleosin, and steroleosin), and their isoelectric point is close to that of soy protein isolate at around 5.0. If the pH is not within this range, self-aggregates will not form, and the viscosity and rheology are not suitable for salad dressing applications.

[0015] Beneficial effects

[0016] The present application provides a method for preparing calcium-fortified plant oil body autopolymers based on charge response. Soybean oil bodies rich in different exogenous / endogenous protein contents can be obtained by light / deep centrifugation, thereby enhancing the charge sensitivity of the system. Calcium is adsorbed by the oil bodies, and milk calcium powder is added to the oil body emulsion at 150 mg / 100 ml and evenly dispersed in the oil body emulsion with good stability, thereby playing a calcium strengthening role. Based on the charge responsiveness, no external polysaccharide is required, and high viscosity and good rheological properties can be obtained by adjusting the acidic conditions. The product can be used in salad dressings as a fat substitute to give food good thixotropic recovery. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is an SDS-PAGE image of endogenous and exogenous proteins in light / deep purification of lipid bodies in Example 1;

[0018] Figure 2 This is a microscopic structure diagram of the milk calcium powder of Example 2 dispersed in lightly / deeply purified oil bodies;

[0019] Figure 3 This is a microscopic structure diagram of the calcium-fortified vegetable oil autopolymer based on charge response in Example 3;

[0020] Figure 4 This is a viscosity comparison chart of the calcium-fortified vegetable oil autopolymer based on charge response in Example 3;

[0021] Figure 5 This is a graph showing the rheological properties of the calcium-fortified vegetable oil autopolymer based on charge response in Example 3;

[0022] Figure 6 This is a sample diagram of the charge-responsive calcium-fortified vegetable oil autopolymer used in salad dressing according to Example 4;

[0023] Figure 7 This is a hysteresis curve diagram of the charge-responsive calcium-fortified vegetable oil autopolymer used in salad dressing according to Example 4;

[0024] Figure 8 The three-zone thixotropic diagram of the charge-responsive calcium-fortified vegetable oil autopolymer of Example 5 and the comparative example applied to salad dressing. DETAILED DESCRIPTION

[0025] The following is a detailed description of an embodiment of the present invention. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process. However, the protection scope of the present invention is not limited to the following embodiment.

[0026] Example 1

[0027] (1) Extraction of soybean oil bodies by light / deep purification: Soybeans were mixed with 0.1M NaHCO3 solution at a mass ratio of 1:7, soaked at 4°C for 20 h, and then blended with a wall breaker for 6 min. The pH was adjusted to 11.0 and stirred in a 50°C water bath for 2 h. The oil body suspension was filtered and centrifuged at 4°C (the centrifugal speed was 5000 rpm and the centrifugal time was 15 min under light / medium purification conditions. The centrifugal speed was 10000 rpm and the centrifugal time was 30 min under deep purification conditions).

[0028] Example 2

[0029] (1) Light / deep purification of soybean oil bodies: soybeans were mixed with 0.1M NaHCO3 solution at a mass ratio of 1:7, soaked at 4°C for 20 h, and then blended with a wall-breaking machine for 6 min. The pH was adjusted to 11.0, stirred in a 50°C water bath for 2 h, and filtered to obtain an oil body suspension. The suspension was centrifuged at 4°C (the centrifugal speed was 5000 rpm and the centrifugal time was 15 min under light / medium purification conditions. The centrifugal speed was 10000 rpm and the centrifugal time was 30 min under deep purification conditions).

[0030] (2) Lightly / deeply purified soybean oil bodies were mixed with deionized water in a volume ratio of 1:1 to prepare an oil body emulsion. Milk calcium powder was added to the oil body emulsion at a concentration of 150 mg / 100 ml at a shear rate of 8000 rpm to allow the milk calcium to be adsorbed on the emulsion interface and then dispersed evenly.

[0031] Example 3

[0032] (1) Light / deep purification of soybean oil bodies: soybeans were mixed with 0.1M NaHCO3 solution at a mass ratio of 1:7, soaked at 4°C for 20 h, and then blended with a wall-breaking machine for 6 min. The pH was adjusted to 11.0, stirred in a 50°C water bath for 2 h, and filtered to obtain an oil body suspension. The suspension was centrifuged at 4°C (the centrifugal speed was 5000 rpm and the centrifugal time was 15 min under light / medium purification conditions. The centrifugal speed was 10000 rpm and the centrifugal time was 30 min under deep purification conditions).

[0033] (2) Lightly / deeply purified soybean oil bodies were mixed with deionized water in a volume ratio of 1:1 to prepare an oil body emulsion. Milk calcium powder was added to the oil body emulsion at a concentration of 150 mg / 100 ml at a shear rate of 8000 rpm to allow the milk calcium to be adsorbed on the emulsion interface and then dispersed evenly.

[0034] (3) Using hydrochloric acid solution, the pH of the slightly purified soybean oil body emulsion loaded with milk calcium was adjusted to 4.5, and the pH of the deeply purified soybean oil body emulsion loaded with milk calcium was adjusted to 5.0.

[0035] Example 4

[0036] (1) Light / deep purification of soybean oil bodies: soybeans were mixed with 0.1M NaHCO3 solution at a mass ratio of 1:7, soaked at 4°C for 20 h, and then blended with a wall-breaking machine for 6 min. The pH was adjusted to 11.0, stirred in a 50°C water bath for 2 h, and filtered to obtain an oil body suspension. The suspension was centrifuged at 4°C (the centrifugal speed was 5000 rpm and the centrifugal time was 15 min under light / medium purification conditions. The centrifugal speed was 10000 rpm and the centrifugal time was 30 min under deep purification conditions).

[0037] (2) Lightly / deeply purified soybean oil bodies were mixed with deionized water in a volume ratio of 1:1 to prepare an oil body emulsion. Milk calcium powder was added to the oil body emulsion at a concentration of 150 mg / 100 ml at a shear rate of 8000 rpm to allow the milk calcium to be adsorbed on the emulsion interface and then dispersed evenly.

[0038] (3) Using hydrochloric acid solution, the pH of the slightly purified soybean oil body emulsion loaded with milk calcium was adjusted to 4.5, and the pH of the deeply purified soybean oil body emulsion loaded with milk calcium was adjusted to 5.0.

[0039] (4) The calcium-fortified vegetable oil autopolymer was mixed evenly with white sugar and salt, and soybean oil was slowly added in batches and beaten quickly, white vinegar was added in batches and beaten at medium speed, and finally defoamed at low speed to prepare the oil salad dressing sample (refer to Table 1 for the ingredient ratio).

[0040] Comparative Example 1

[0041] The whole eggs were shelled, the egg white and yolk were mixed evenly, white sugar and salt were added and mixed evenly, soybean oil was slowly added in batches and beaten quickly, white vinegar was added in batches and beaten at medium speed, and finally defoamed at low speed to prepare the oil-based salad dressing sample (refer to Table 1 for the ingredient ratio).

[0042]

[0043] 1. Physical and chemical properties testing

[0044] 1. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE)

[0045] The interfacial protein solution was heat-denatured after adding 5× protein loading buffer (containing DTT). Electrophoresis was performed at 80 V, 5% stacking gel concentration and 120 V, 12% separation gel concentration. The gel was stained with Coomassie Brilliant Blue R250 and then destained.

[0046] 2. Microstructure Testing Method: Add Nile Red and Nile Blue dyes to the sample in the appropriate proportions and stir for 40 minutes in the dark to stain the protein and oil phases, respectively. Next, place 0.1 μL of the sample solution on the center of a dry glass slide. Gently cover with a glass slide and apply gentle pressure to prevent air bubbles. Observe under an FV3000 confocal laser microscope, adjusting the excitation wavelengths to 488 nm and 576 nm. Adjust the microscope to locate the target location, observe and record the results, and then photograph the confocal laser image.

[0047] 3. Sample Viscosity Test Method: The apparent viscosity of the samples was determined by continuous shear testing using a Haake RheoStress rheometer. Shear viscosity: Parameters: Spindle CC27 DG / Ti, shear rate 0.1-100 s⁻¹, time 60 s, 65 data points, test temperature 25°C, three replicates. Frequency sweep: Parameters: Spindle CC27 DG / Ti, shear stress 0.1 Pa, frequency sweep parameter 1-15 Hz, 60 data points, test temperature 25°C, three replicates. Amplitude sweep: Parameters: Spindle CC27 DG / Ti, strain sweep parameter 0.1%-100%, 60 data points, test temperature 25°C, three replicates.

[0048] 4. Three-zone Thixotropy (3ITT) test method:

[0049] The three-zone thixotropy adopts a low-high-low oscillatory shear program, and the thixotropy test is carried out in three intervals at a constant angular frequency of 1 rad / s. The first and third intervals are carried out at a low stress value of 0.001 Pa for 120s and 240s respectively. The second interval selects different stress values ​​of 0.01Pa, 0.05Pa, 0.1Pa and 0.5Pa, and high shear is carried out at a constant angular frequency of 1 rad / s for 120s in the second interval.

[0050] 5. Hysteresis test method:

[0051] The hysteresis experiments used shear rates from low to high and from high to low of 0.001–100 (1 / s) with different durations (10s, 100s).

[0052] from Figure 1 It can be seen that the protein composition of soybean oil bodies extracted by light centrifugation and deep centrifugation is quite different. The number of protein bands in deep centrifugation is relatively small, and the content of exogenous protein is low; the content of protein bands in light centrifugation is relatively large, and the content of exogenous protein is high.

[0053] from Figure 2 It can be seen that milk calcium is adsorbed on the interface layer of soybean oil bodies extracted by light centrifugation and deep centrifugation;

[0054] from Figure 3 It can be seen that compared with the unadjusted pH of liposomes, light centrifugation and deep centrifugation lowered the pH to 4.5 and 5.0, respectively, and the liposome proteins were cross-linked to form a network structure;

[0055] from Figure 4 It can be seen that after lowering the pH value, the viscosity of the calcium-fortified vegetable oil autopolymer based on charge response is significantly increased compared with the untreated oil autopolymer;

[0056] from Figure 5 It can be seen that the calcium-fortified vegetable oil self-aggregates based on charge response have greater viscoelasticity, and the frequency sweep and strain sweep show semi-solid characteristics, while the untreated oil body shows low-viscosity liquid characteristics;

[0057] from Figure 6 It can be seen that compared with the whole egg salad dressing of the control, the salad dressing prepared by the charge-responsive calcium-fortified plant oil autopolymer has a brighter color, moderate viscosity, and good eating and spreading properties.

[0058] Figure 7The hysteresis curve represents the hysteresis phenomenon that occurs between the rising and falling stages of the sample's steady-state flow curve. As can be seen from the figure, at the same shear rate, the stress value during the rising stage is always greater than the stress value during the falling stage. The stress-shear rate curve for the entire cycle forms a complete closed loop, indicating that all samples exhibit thixotropy. The salad dressing prepared from the charge-responsive calcium-fortified vegetable oil autopolymers and the whole egg control sample exhibit distinct curves after cycling from low to high and from high to low shear rates. The salad dressing prepared from the vegetable oil autopolymers has a larger hysteresis area and stronger recovery.

[0059] Figure 8 This is a three-stage thixotropic recovery experiment. This test method can better simulate the relationship between shear stress and shear rate during the delivery and instantaneous stirring of food materials during processing. The figure shows that the G' and G'' values ​​of the whole egg control salad dressing are smaller and G' <G’’,在0.05Pa、0.1Pa,0.5Pa应力下G’和G’’均出现明显的变小,这表示施加的压力使油脂体沙拉酱变形,而通过植物油脂体自聚体所制备沙拉酱的G’值均大于G’’,表明样品具有明显的粘弹性特质,且在0.01Pa、0.05Pa、0.1Pa应力下无明显变化;

[0060] It should be noted that charge-responsive calcium-fortified vegetable oil autopolymers were prepared through light / deep centrifugation. Milk calcium was stably adsorbed at the emulsion interface, significantly increasing shear viscosity and maintaining a relatively smooth viscosity curve. Frequency sweeps showed elasticity with G' > G'', while amplitude sweeps demonstrated enhanced deformation resistance, forming a permeable, isolating network structure. Application of this in salad dressings imparts excellent thixotropic recovery, facilitating spreadability. The salad dressing exhibits complete structural recovery, allowing more time to return to a relaxed state after being disrupted during shear rate increases. This product can be used as a calcium fortifier and, in salad dressings, as a fat substitute, imparting favorable rheological properties to foods.

[0061] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. A method for preparing calcium-fortified vegetable oil autopolymers based on charge response, characterized in that: The following steps are involved: (1) Light / deep purification of soybean oil bodies: soybeans were mixed with 0.1M NaHCO3 solution at a mass ratio of 1:7, soaked at 4°C for 18 h, blended with a wall-breaking machine for 6 min, adjusted to pH 11, stirred in a 50°C water bath for 2 h, filtered to obtain an oil body suspension, and centrifuged at 4°C; (2) Adsorption of milk calcium by grease bodies: lightly / deeply purified soybean grease bodies were mixed with deionized water, milk calcium powder was added to the grease body emulsion, and the sample was sheared to disperse the milk calcium uniformly; lightly / deeply purified soybean grease bodies were mixed with deionized water in a volume ratio of 1:1; milk calcium powder was added to the grease body emulsion at a rate of 150 mg / 100 ml, and the shear rate was 8000 rpm; (3) Charge-responsive plant oil-based self-polymer fat substitute: Using hydrochloric acid solution to adjust the pH of the oil-based emulsion, the originally highly fluid emulsion is instantly transformed into a highly viscous cream; The pH of the slightly purified soybean oil emulsion loaded with lactic calcium was adjusted to 4.5 using a hydrochloric acid solution; The pH of the deeply purified soybean oil emulsion loaded with milk calcium was adjusted to 5.0 using hydrochloric acid solution.

2. The method for preparing calcium-fortified vegetable oil autopolymers based on charge response according to claim 1, characterized in that: In step (1), the centrifugal speed is 5000 rpm and the centrifugal time is 15 min under the mild purification condition; the centrifugal speed is 10000 rpm and the centrifugal time is 30 min under the deep purification condition.

Images