Microencapsulated oil powder based on modified yeast protein-yeast dietary fiber and its preparation method and application

Abstract

The present application belongs to the technical field of food processing, and particularly relates to a microcapsule oil powder based on modified yeast protein-yeast dietary fiber as well as a preparation method and application thereof. The present application first performs heat treatment, pH shift and HPH treatment on yeast protein in combination, and the quality of the yeast protein treated by the three methods in combination is significantly improved in terms of solubility, water and oil holding capacity, particle size and the like. On this basis, the modified yeast protein-yeast dietary fiber is used as a wall material to embed plant oil components to form a microcapsule oil powder, and the embedding rate and thermal stability of the microcapsule oil powder are more excellent than the compounding effect of unmodified yeast protein or other types of protein and yeast dietary fiber. When the microcapsule oil powder is used for baking of bread, the gas retention capacity of the dough can be improved, the hardness and chewiness of the bread can be reduced, the aging of the bread can be delayed, and the shelf life can be prolonged. The microcapsule oil powder can effectively replace traditional butter and partially hydrogenated oil, and is applied to various food processing and baking fields.

Description

Technical Field

[0001] This invention belongs to the field of food processing technology, and specifically relates to a microcapsule oil powder based on modified yeast protein-yeast dietary fiber, its preparation method and application. Background Technology

[0002] Microencapsulated oil powders are powdered products with good flowability and stability, formed by encapsulating liquid oils in a wall material through processes such as emulsification, homogenization, and spray drying. They not only prevent oil oxidation and deterioration, mask undesirable flavors, and extend shelf life, but also improve the dispersibility and handling convenience of oils in food processing. Therefore, microencapsulated oil powders have broad application prospects in baked goods, meat products, dairy products, and functional foods.

[0003] In recent years, yeast protein and yeast dietary fiber have become highly promising natural raw material sources for microencapsulated oil powders due to their wide availability and rich nutritional composition of amino acids and dietary fiber, which meet the needs of functional food consumption. For example, patent CN121942773A discloses a technical solution for preparing powdered oil using yeast protein and yeast dietary fiber, and patent CN118141092A discloses a technical solution for preparing fat analogs using yeast protein and yeast dietary fiber.

[0004] However, the molecular structure of natural yeast protein is relatively dense, with insufficient exposure of hydrophobic groups, resulting in poor water solubility, emulsifying activity, and interfacial activity. It also leads to uneven dispersion in the aqueous phase. If directly used in microcapsule preparation, it easily causes problems such as low encapsulation efficiency and oil phase leakage, resulting in high oil content on the surface of the oil powder and easy oxidation and rancidity during storage. Furthermore, if applied to the preparation of baked goods such as bread, its poor thermal stability leads to denaturation and aggregation after high-temperature baking and other processes, resulting in loss of emulsifying and water-holding functions, as well as dull crust color and cracking. Therefore, it is essential to modify natural yeast protein to improve its binding effect with dietary fiber. Currently, protein modification methods mainly include physical methods (high-pressure homogenization, ultrasound, microwave), chemical methods (glycosylation, acylation, phosphorylation), biological methods (enzymatic hydrolysis), and their combined modifications. However, the performance improvement of yeast protein varies significantly after treatment by different methods, each with its own shortcomings.

[0005] Therefore, by modifying yeast protein and systematically optimizing its emulsifying and solubilizing properties, developing a modified yeast protein-yeast dietary fiber microcapsule powder oil and its preparation method is of great practical significance for expanding the high-value utilization of yeast resources, developing green and sustainable microcapsule wall material systems, and improving the quality of baked goods. Summary of the Invention

[0006] To address the above technical problems, this invention proposes a microcapsule oil powder based on modified yeast protein-yeast dietary fiber, its preparation method, and its application.

[0007] The technical solution provided by this invention specifically includes the following aspects:

[0008] The first aspect of this invention is to provide the application of yeast dietary fiber and modified yeast protein in the preparation of microcapsule oil powder, wherein the mass ratio of yeast dietary fiber to modified yeast protein is 1:1~2; the method for preparing the modified yeast protein is as follows:

[0009] (1) Take yeast protein powder, add water, stir at room temperature, and prepare a yeast protein solution;

[0010] (2) Adjust the pH of the yeast protein solution in (1) to 11.0~12.0 and perform high-pressure microjet treatment at 10~30 MPa 1~3 times;

[0011] (3) Heat the solution after (2) at a temperature of 60-95℃ for 10-40 minutes, then adjust the pH of the solution to 7.0, centrifuge, take the supernatant, freeze dry, and obtain the modified yeast protein.

[0012] In the above-mentioned applications provided by the present invention, preferably, the microcapsule oil powder uses yeast dietary fiber and modified yeast protein as wall materials, adds emulsifier mono- and diglyceride fatty acid esters, and uses vegetable oil as core material. The emulsifier is added to the vegetable oil and mixed with the wall materials dissolved in water. The mixture is stirred at 40~60℃ for 20~50 min, then homogenized at 10000~15000 rpm / min for 1~3 min, freeze-dried under vacuum into a solid, and pulverized to obtain the microcapsule oil powder.

[0013] Preferably, by weight, the microcapsule oil powder contains 10-15 parts of wall material, 1-5 parts of emulsifier, 25-40 parts of vegetable oil, and 40-60 parts of water, and the mass ratio of yeast dietary fiber to modified yeast protein in the wall material is 1:1.

[0014] Preferably, the vegetable oil is selected from any one of flaxseed oil, rice bran oil, rice bran oil, and olive oil.

[0015] A second aspect of the present invention is to provide a method for preparing a microcapsule oil powder based on modified yeast protein-yeast dietary fiber, comprising the following steps:

[0016] S1 Preparation of modified yeast protein: Modified yeast protein is prepared according to the method provided in the first aspect of the present invention;

[0017] Preparation of S2 aqueous phase: Yeast dietary fiber and modified yeast protein obtained from S1 were mixed in a 1:1 mass ratio and used as wall material. Water was added to dissolve the mixture and prepare a wall material solution.

[0018] Preparation of S3 oil phase: Vegetable oil is used as the core material, and emulsifier mono- and diglyceride fatty acid esters are added and mixed to form the oil phase. The mass ratio of the emulsifier to the vegetable oil is 1:9~12.

[0019] S4: Add the oil phase of S3 to the aqueous phase of S2, stir at 40~60℃ for 20~30 min, then homogenize at high speed at 12000~15000 rpm / min for 2~3 min, freeze dry under vacuum to form a solid, and then pulverize to obtain the final product.

[0020] In the method for preparing the microcapsule oil powder provided by the present invention, preferably, the mass percentage of each component, based on the mass of the oil powder, is as follows:

[0021] In S2, yeast dietary fiber is 6%, modified yeast protein obtained from S1 is 6%, and water is 53%.

[0022] In S3, there is 32% vegetable oil and 3% emulsifier. The vegetable oil in S3 is selected from any one of flaxseed oil, rice bran oil, and olive oil.

[0023] As a further preferred option, the vegetable oil mentioned in S3 is flaxseed oil.

[0024] A third aspect of the present invention is to provide the application of the microcapsule oil powder prepared by the above-described preparation method in bread preparation, wherein, preferably, the microcapsule oil powder is used to improve the specific volume and texture of bread.

[0025] A fourth aspect of the present invention is to provide a butter-free bread, wherein the bread uses microcapsule oil powder prepared with yeast dietary fiber and modified yeast protein powder as wall materials to replace butter.

[0026] Preferably, the bread comprises, by weight, 150-300 parts high-gluten flour, 5-20 parts white sugar, 1-3 parts edible salt, 2.5-5 parts dry yeast, 3-10 parts microcapsule oil powder, and 50-150 parts water.

[0027] As a further preferred embodiment, the bread comprises, by weight, 200 parts high-gluten flour, 16 parts white sugar, 2 parts edible salt, 3.2 parts dry yeast, 8 parts microcapsule oil powder, and 120 parts water.

[0028] Preferably, when preparing bread, the above ingredients are first mixed and kneaded, then proofed at 37°C and 80% relative humidity for 60 minutes, and finally baked in an oven at 170°C for 20 minutes.

[0029] The present invention has the following advantages and effects compared with the prior art:

[0030] (1) The microcapsule oil powder made by encapsulating vegetable oil with modified yeast protein-yeast dietary fiber as the wall material in this invention has significantly improved oil loading and oil encapsulation rate compared with the unmodified yeast protein-yeast dietary fiber group, soybean protein isolate-yeast dietary fiber group, or the group using modified yeast protein and other types of polysaccharides such as β-cyclodextrin and isomaltooligosaccharide, with an encapsulation rate of 85.35%. In addition, the microcapsule oil powder has a more uniform and smaller particle size, with an average particle size of about 1131 nm. Its stability and resolubility are also significantly improved.

[0031] (2) The modified yeast protein-yeast dietary fiber microcapsule oil powder prepared in this invention was applied to bread, which significantly improved the softness of the bread. The hardness, chewiness and other parameters of the bread were improved compared with other types of protein-polysaccharide compound, and the bread was more palatable. In addition, the degree of aging of the bread during storage was also reduced compared with other protein-polysaccharide compound systems.

[0032] (3) The present invention treats yeast protein by heat treatment, pH shifting and HPH treatment. The yeast protein treated by these three methods is significantly better than the modified yeast protein treated by single modification or combined modification by two methods in terms of solubility, water and oil holding capacity and particle size. Attached Figure Description

[0033] Figure 1 The images show the microstructure of the microcapsule oil powders prepared in Example 1 and Comparative Examples 1-8 of this invention.

[0034] Figure 2 Zeta potential diagrams of the crude emulsions of microcapsule oil powders prepared in Example 1 and Comparative Examples 1-8 of this invention;

[0035] Figure 3 Thermogravimetric analysis (TGA) curves and differential thermogravimetric analysis (DTG) curves of the microcapsule oil powders prepared in Example 1 and Comparative Examples 1-8 of this invention.

[0036] Figure 4 The microstructure and Zeta potential diagrams of the microcapsule oil powders prepared in Example 1 and Comparative Examples 1-8 of this invention after reconstitution are shown.

[0037] Figure 5 The TSI images are of the microcapsule oil powders prepared in Example 1 and Comparative Examples 1-8 of this invention after reconstitution.

[0038] Figure 6The texture diagrams are of breads made from different microcapsule oil powders in Experimental Example 1 of this invention.

[0039] Figure 7 This is a specific volume diagram of bread made from different microcapsule oil powders in Experimental Example 1 of the present invention.

[0040] Figure 8 This is an internal structure diagram of bread made from different microcapsule oil powders in Experimental Example 1 of the present invention;

[0041] Figure 9 This is a graph showing the change in hardness during storage of bread made from different microcapsule oil powders in Experiment Example 1 of the present invention.

[0042] Figure 10 The texture diagrams are of breads made from different microcapsule oil powders in Experimental Example 2 of this invention.

[0043] Figure 11 These are internal structural diagrams of different breads used in Experimental Example 2 of this invention;

[0044] Figure 12 This is a graph showing the change in hardness of bread made from different microcapsule oil powders during storage in Experiment Example 2 of the present invention.

[0045] Figure 13 The diagram shows the solubility and turbidity of the modified yeast protein obtained in Comparative Example 9 of this invention.

[0046] Figure 14 The graph shows the water-holding and oil-holding properties of the modified yeast protein obtained in Comparative Example 9 of this invention.

[0047] Figure 15 This is a microstructure diagram (magnified 8000 times) of the modified yeast protein obtained in Comparative Example 9 of the present invention.

[0048] Figure 16 This is a diagram showing the surface hydrophobicity of the modified yeast protein obtained in Comparative Example 9 of the present invention. Detailed Implementation

[0049] To enable those skilled in the art to better understand the present invention, further description is provided below in conjunction with specific embodiments. The yeast protein and yeast dietary fiber used in this invention are provided by Angel Yeast Co., Ltd. Unless otherwise specified, conditions in this invention are performed under conventional conditions or conditions recommended by the manufacturer. Unless otherwise specified, the raw materials used in the following examples are all commercially available.

[0050] The codes for the components involved in this invention are as follows:

[0051] YP: Yeast protein, MYP: Modified yeast protein, β-CD: β-cyclodextrin, IMO: Isomaltooligosaccharide, YDF: Yeast dietary fiber, FO: Flaxseed oil, B: Butter, RBO: Rice bran oil, OO: Olive oil.

[0052] Example 1

[0053] A modified yeast protein-yeast dietary fiber microencapsulated oil powder was prepared using the following method:

[0054] S1 Preparation of modified yeast protein: First, weigh a certain mass (100 mg) of yeast protein powder (YP), add 100 mL of water, and stir evenly at a rate of 500 r / min at room temperature (about 30 min) to prepare a yeast protein solution with a concentration of 1% (w / v). Then, adjust the pH of the yeast protein solution to 12.0 with 1M NaOH, perform high-pressure microjet treatment once at a pressure of 20 MPa, and then heat treat at 90℃ for 30 min. Finally, adjust the pH to 7.0 with 1M HCl, centrifuge, take the supernatant and freeze at -20℃, freeze dry for 48 hours, pulverize, and classify and sieve with a 100-mesh sieve to obtain modified yeast protein;

[0055] Preparation of S2 aqueous phase: Yeast dietary fiber (YDF) (6%, w / w) and modified yeast protein (6%, w / w) obtained in S1 were mixed and used as wall material, and dissolved in water (53%, w / w) to prepare wall material solution;

[0056] Preparation of S3 oil phase: Flaxseed oil (32%, w / w) was used as the core material, and emulsifier mono- and diglyceride fatty acid esters (3%, w / w) were added and mixed.

[0057] In this invention, the mass percentages of each component involved in S2 and S3 are calculated based on the mass of the oil powder.

[0058] S4: Add the oil phase of S3 to the aqueous phase of S2, stir at 50°C for 30 min to mix evenly, then homogenize at 13000 rpm / min for 2 min, freeze dry under vacuum to form a solid, and pulverize to obtain the final product.

[0059] Example 2

[0060] Unlike Example 1, in S3 of this example, rice bran oil (RBO) is used instead of flaxseed oil to prepare microcapsule oil powder.

[0061] Example 3

[0062] Unlike Example 1, in S3 of this example, olive oil (OO) is used instead of flaxseed oil to prepare microcapsule oil powder.

[0063] Comparative Example 1

[0064] The only difference from Example 1 is that in S2, YP and β-CD were combined to prepare microcapsule oil powder.

[0065] Comparative Example 2

[0066] The only difference from Example 1 is that in S2, YP and IMO were combined to prepare microcapsule oil powder.

[0067] Comparative Example 3

[0068] The only difference from Example 1 is that in S2, YP and YDF were combined to prepare microcapsule oil powder.

[0069] Comparative Example 4

[0070] The only difference from Example 1 is that in S2, soy protein isolate (SPI) and β-CD were combined to prepare microcapsule oil powder.

[0071] Comparative Example 5

[0072] The only difference from Example 1 is that in S2, microcapsule oil powder is prepared by combining SPI and IMO.

[0073] Comparative Example 6

[0074] The only difference from Example 1 is that in S2, SPI and YDF were combined to prepare microcapsule oil powder.

[0075] Comparative Example 7

[0076] The only difference from Example 1 is that in S2, β-CD is used instead of YDF to prepare microcapsule oil powder in combination with MYP.

[0077] Comparative Example 8

[0078] The only difference from Example 1 is that in S2, IMO is used instead of YDF to prepare microcapsule oil powder in combination with MYP.

[0079] Table 1. Oil loading, surface oil content, and encapsulation efficiency of different microcapsule oil powders Comparative Example 1 YP-β-CD <![CDATA[80.14±0.26 d ]]> <![CDATA[44.68±0.16 a ]]> <![CDATA[44.25±0.2 f ]]> Comparative Example 2 YP-IMO <![CDATA[78.54±0.58 cd ]]> <![CDATA[31.17±0.85 c ]]> <![CDATA[60.41±0.79 d ]]> Comparative Example 3 YP-YDF <![CDATA[80.63±1.00 bc ]]> <![CDATA[18.43±1.65 e ]]> <![CDATA[77.15±1.77 b ]]> Comparative Example 4 SPI-β-CD <![CDATA[78.24±0.40 d ]]> <![CDATA[24.46±2.32 d ]]> <![CDATA[68.76±2.80 c ]]> Comparative Example 5 SPI-IMO <![CDATA[77.52±0.01 d ]]> <![CDATA[25.59±0.06 d ]]> <![CDATA[66.99±0.08 c ]]> Comparative Example 6 SPI-YDF <![CDATA[79.20±0.55 bcd ]]> <![CDATA[20.43±0.60 e ]]> <![CDATA[74.21±0.57 b ]]> Comparative Example 7 MYP-β-CD <![CDATA[82.52±0.08 a ]]> <![CDATA[37.47±0.34 b ]]> <![CDATA[54.60±0.46 e ]]> Comparative Example 8 MYP-IMO <![CDATA[82.30±0.65 ab ]]> <![CDATA[14.16±0.51 f ]]> <![CDATA[82.79±0.75 a ]]> Example 1 MYP-YDF <![CDATA[83.81±0.39 a ]]> <![CDATA[12.28±0.83 f ]]> <![CDATA[85.35±0.92 a ]]>

[0080] The microstructure, crude emulsion zeta potential, and thermal stability of the microcapsule oil powders obtained in Example 1 and Comparative Examples 1-8 are as follows: Figures 1-3 As shown.

[0081] As shown in the figure, the oil droplets (red) of the YP group microcapsule oil powder are the largest and most dispersed. Among the three control protein SPI groups, SPI-YDF has larger oil droplets, while the MYP groups have smaller, more uniformly distributed oil droplets, with MYP-IMO exhibiting relatively uniform and dense oil droplet particles. Regarding particle size, the YP-YDF combination has the largest particle size at 4828 nm, while the IMO and β-CD groups generally have medium particle sizes. MYP-IMO has the smallest particle size at 1131 nm. This indicates that MYP protein is more conducive to forming small-particle-size, highly dispersible emulsions. Furthermore, referring to Table 1 and... Figures 2-3 It is evident that MYP-YDF exhibits the best embedding effect and oil retention.

[0082] In addition, 0.5 g of each oil powder sample was dispersed in deionized water, magnetically stirred for 20 min, and then filtered. The filter residue was collected, heated to constant weight at 105℃, and weighed. The solubility of the powdered oil in water was then calculated using the following formula: Solubility (%) = (Total weight of powder - Weight of filter residue) / Total weight of powder × 100. The solubility of different oil powders after reconstitution is shown in Table 2 below, and their microstructure, potential, and TSI value changes are as follows: Figure 4 , Figure 5 As shown.

[0083] Table 2. Moisture content, hygroscopicity, and solubility of different microcapsule oil powders Comparative Example 1 YP-β-CD <![CDATA[1.99±0.03 a ]]> <![CDATA[2.62±0.24 bc ]]> <![CDATA[89.02±0.51 e ]]> Comparative Example 2 YP-IMO <![CDATA[1.03±0.14 bc ]]> <![CDATA[3.04±0.58 ab ]]> <![CDATA[92.99±0.55 bcd ]]> Comparative Example 3 YP-YDF <![CDATA[0.96±0.06 c ]]> <![CDATA[2.65±0.39 bc ]]> <![CDATA[93.17±0.15 abcd ]]> Comparative Example 4 SPI-β-CD <![CDATA[1.70±0.04 a ]]> <![CDATA[2.91±0.13 bc ]]> <![CDATA[91.76±0.02 cd ]]> Comparative Example 5 SPI-IMO <![CDATA[1.84±0.01 a ]]> <![CDATA[3.74±0.26 ab ]]> <![CDATA[90.51±1.18 de ]]> Comparative Example 6 SPI-YDF <![CDATA[1.81±0.03 a ]]> <![CDATA[2.33±0.55 c ]]> <![CDATA[90.54±1.72 de ]]> Comparative Example 7 MYP-β-CD <![CDATA[1.00±0.18 c ]]> <![CDATA[3.74±0.03 bc ]]> <![CDATA[94.89±0.55 ab ]]> Comparative Example 8 MYP-IMO <![CDATA[0.49±0.04 d ]]> <![CDATA[4.26±0.02 a ]]> <![CDATA[94.26±0.35 abc ]]> Example 1 MYP-YDF <![CDATA[1.34±0.15 b ]]> <![CDATA[4.17±0.13 a ]]> <![CDATA[95.80±0.62 a ]]>

[0084] Table 2 combined with Figure 4 It can be seen that the rehydration solubility of each oil powder is 89%~95.8%, with MYP-YDF having the highest solubility, followed by MYP-IMO and MYP-β-CD. This indicates that MYP has good compatibility with YDF, IMO and β-CD and can form more stable water-soluble complexes.

[0085] in addition Figure 5 The results show that MYP-YDF has the lowest TSI value and the smallest slope, followed by the MYP-β-CD group. SPI-β-CD has a lower TSI value than the YP group, with a smooth upward curve. The YP group has the highest TSI value. When YP is combined with IMO or YDF, the system is extremely unstable. This demonstrates that the MYP obtained by modifying YP in this invention significantly improves its compatibility with functional polysaccharides. The modified protein has increased hydrophilicity, can resist the phase separation effect caused by polysaccharides, significantly reduces the TSI value, and enhances the physical stability of the composite system.

[0086] Application Example 1

[0087] A type of bread that does not contain butter is prepared using the following method:

[0088] First, mix 200 g of high-gluten flour, 16 g of white sugar, 2 g of salt, and 3.2 g of dry yeast evenly, then add them to a dough mixer and mix at low speed for 6 minutes. Next, add 120 g of water evenly to the dough mixer and mix at low speed for 6 minutes. Finally, add 8 g of the microcapsule oil powder prepared in Example 1 and mix at high speed for 6 minutes. After degassing the prepared dough, divide it into 50 g portions, roll them into balls, and place them in a proofing box at 37°C and 85% relative humidity for 60 minutes. Finally, bake them in an oven at 170°C (top and bottom heat) for 20 minutes, then remove them and let them cool at room temperature for 60 minutes.

[0089] Application Example 2

[0090] The only difference from Application Example 1 is that in this application example, bread is prepared using the microcapsule oil powders prepared in Examples 2 and 3, respectively, while bread prepared using rice bran oil and olive oil instead of the microcapsule oil powders in Examples 2 and 3 serves as a control.

[0091] Application Example 3

[0092] The only difference from Application Example 1 is that the microcapsule oil powder used in this application example was prepared according to the methods in Comparative Examples 1 to 8; at the same time, bread prepared using butter and flaxseed oil instead of microcapsule oil powder was used as a control.

[0093] Experimental Example 1

[0094] The hardness and chewiness of the bread prepared in Example 1 and Application Example 3 were analyzed using a texture analyzer, and the results are as follows: Figure 6 As shown, the specific volume and internal structure of the bread are as follows: Figure 7 , Figure 8 As shown.

[0095] Figure 6 It is evident that when microencapsulated oil powders prepared with SPI and YP are used in bread, the bread exhibits higher hardness and chewiness, resulting in an overall firmer texture. In contrast, bread made with microencapsulated oil powder containing MYP shows a significantly reduced hardness, resulting in a softer and more chewy texture. Furthermore, microencapsulated oil powders prepared by combining YDF and IMO with MYP demonstrate a greater effect on improving bread quality compared to β-CD.

[0096] Figure 7 It is evident that the bread made from the MYP-YDF microcapsule oil powder group has the highest specific volume. A higher specific volume indicates a larger bread volume and a softer texture. Figure 8 Similarly, the same conclusion can be drawn: the MYP-YDF microcapsule oil powder group has the most uniform pore distribution, moderate pore size, and loose overall structure, which is completely consistent with the result of the highest specific volume.

[0097] After baking, the bread was cooled at room temperature for 1 hour, then sealed in a bag and stored in a refrigerator at 4°C for 0, 1, 3, and 5 days. At each time point, the bread was removed and its hardness was measured using a texture analyzer. The results are shown below. Figure 9 .

[0098] Figure 9 It is evident that the bread in the MYP-YDF microcapsule oil powder group had the lowest hardness, and the hardness increased slowly over time. It was the slowest to age and had the best anti-hardening effect among all groups. Even after 5 days of storage, it still maintained a low hardness. This shows that the addition of MYP-YDF microcapsule oil powder can effectively extend the soft shelf life of bread.

[0099] Experimental Example 2

[0100] The texture, hardness, chewiness, and other qualities of the bread prepared in Example 2 were measured, among which... Figure 10 The results show the hardness, chewiness, and other parameters of bread prepared using rice bran oil and olive oil as the core material for microencapsulated oil powders. Figure 11 This is a diagram of the internal structure of bread. Figure 12 A graph showing the change in the hardness of bread after 5 days.

[0101] The results in the figure show that MYP-YDF microcapsule oil powders with different vegetable oils as core materials can effectively improve bread texture and enhance softness and palatability. Among them, the hardness, chewiness, and adhesiveness of the MYP-YDF-RBO and MYP-YDF-OO samples are generally similar, with only minor differences, indicating that the type of core material has a certain impact on the texture characteristics of bread.

[0102] In addition, from Figure 11 As can be seen, although the MYP-YDF-OO and MYP-YDF-RBO microcapsule oil powder groups have a higher number of pores, they are still inferior to the MYP-YDF-FO microcapsule oil powder group. Figure 12 After 5 days of storage, the hardness of the MYP-YDF-OO and MYP-YDF-RBO microcapsule oil powder groups changed significantly more than that of the MYP-YDF-FO microcapsule oil powder group.

[0103] In addition to the experiments mentioned above, the inventors also conducted the following experiments during the modification of yeast protein. However, due to unsatisfactory parameters obtained from the obtained yeast protein, the inventors did not continue to use the following experimental conditions to modify the yeast protein and prepare microcapsule oil powder. Some of the experiments and data are as follows:

[0104] Comparative Example 9

[0105] A modified yeast protein, prepared by the following method:

[0106] 100 mg YP was dispersed in 100 mL of water and stirred at 500 r / min at room temperature for about 30 min to prepare a 1% (w / v) yeast protein solution. The solution was then divided into four groups: heat treatment group, pH shift group, heat treatment-pH shift combined group, pH shift-HPH group (i.e., pH shift-high pressure microfluidic treatment group), and heat treatment-pH shift-HPH group. The specific treatment conditions for each group are shown in the table below.

[0107] Table 3. Treatment groups and corresponding modification conditions Heat Treatment Group-1 The yeast protein solution was heated at 60°C for 30 min and then cooled. Heat Treatment Group-2 The yeast protein solution was heated at 90°C for 30 min and then cooled. pH offset group After adjusting the pH of the yeast protein solution to 12.0, stir for 2 hours, then adjust back to neutral. Heat treatment-pH shift composite group-1 The yeast protein solution was first adjusted to pH 12.0, stirred for 2 hours, heated at 60℃ for 30 minutes, and then adjusted back to neutral. Heat treatment-pH shift composite group-2 The yeast protein solution was first adjusted to pH 12.0, stirred for 2 hours, heated at 90℃ for 30 minutes, and then adjusted back to neutral. pH Shift - HPH Group The yeast protein solution was first adjusted to pH 12.0 and stirred for 2 h, then subjected to a pH treatment at 20 MPa once to bring it back to neutral. Heat treatment - pH shift - HPH group - 1 The yeast protein solution was first adjusted to pH 12.0 and stirred for 2 hours, then subjected to a pH treatment at 20 MPa once, followed by a heat treatment at 60℃ for 30 minutes, and finally adjusted back to neutral. Heat treatment - pH shift - HPH group - 2 The yeast protein solution was first adjusted to pH 12.0 and stirred for 2 hours, then subjected to a pH treatment at 20 MPa once, followed by a heat treatment at 90℃ for 30 minutes, and finally adjusted back to neutral.

[0108] The solubility and turbidity, water-holding capacity and oil-holding capacity, microstructure (8000x magnification), and surface hydrophobicity of the modified yeast proteins obtained by the above different treatments are as follows: Figures 14-16 As shown.

[0109] The comparison of the above results shows that the combined treatment of pH shift with HT and / or HPH can alter the secondary structure and molecular conformation of yeast proteins, promoting the full unfolding of the protein structure, reducing protein particle size, increasing the content of small molecules, and exposing hydrophobic / hydrophilic groups, thereby improving its solubility, water-holding capacity, and oil-holding capacity. Among these, the modification method of pH 12-HPH-90℃ achieved the highest values ​​for YP's solubility, water-holding capacity, and oil-holding capacity; therefore, this condition was adopted as the optimal condition for yeast protein modification in this invention.

[0110] The above are merely preferred embodiments of the present invention and do not limit the scope of the patent. All equivalent changes and modifications made within the scope of the present invention should still fall within the scope of the present invention.

Claims

1. The application of yeast dietary fiber and modified yeast protein in the preparation of microencapsulated oil powder, characterized in that, The mass ratio of yeast dietary fiber to modified yeast protein is 1:1~2; The modified yeast protein is prepared as follows: (1) Take yeast protein powder, add water, stir at room temperature, and prepare a yeast protein solution; (2) Adjust the pH of the yeast protein solution in (1) to 11.0~12.0 and perform high-pressure microjet treatment at 10~30 MPa 1~3 times; (3) Heat the solution after (2) at a temperature of 60-95℃ for 10-40 min, then adjust the pH of the solution to 7.0, centrifuge and take the supernatant, freeze dry to obtain the modified yeast protein.

2. The application as described in claim 1, characterized in that, The microcapsule oil powder uses yeast dietary fiber and modified yeast protein as wall materials, adds emulsifier mono- and diglyceride fatty acid esters, and uses vegetable oil as core material. The emulsifier is added to the vegetable oil and mixed with the wall materials dissolved in water. The mixture is stirred at 40~60℃ for 20~50 min, then homogenized at 10000~15000 rpm / min for 1~3 min, freeze-dried under vacuum into a solid, and pulverized to obtain the microcapsule oil powder.

3. The application as described in claim 2, characterized in that, By weight, the microcapsule oil powder contains 10-15 parts wall material, 1-5 parts emulsifier, 25-40 parts vegetable oil, and 40-60 parts water. In the wall material, the mass ratio of yeast dietary fiber to modified yeast protein is 1:

1.

4. The application as described in claim 2, characterized in that, The vegetable oil is selected from any one of flaxseed oil, rice bran oil, rice bran oil, and olive oil.

5. A method for preparing microencapsulated oil powder based on modified yeast protein-yeast dietary fiber, characterized in that, The steps include the following: S1 Preparation of modified yeast protein: Prepare modified yeast protein according to the method of claim 1; Preparation of S2 aqueous phase: Yeast dietary fiber and modified yeast protein obtained from S1 were mixed in a 1:1 mass ratio and used as wall material. Water was added to dissolve the mixture and a wall material solution was prepared. Preparation of S3 oil phase: Vegetable oil is used as the core material, and emulsifier mono- and diglyceride fatty acid esters are added and mixed to form the oil phase. The mass ratio of the emulsifier to the vegetable oil is 1:9~12. S4: Add the oil phase of S3 to the aqueous phase of S2, stir at 40~60℃ for 20~30 min, then homogenize at high speed at 12000~15000 rpm / min for 2~3 min, freeze dry under vacuum to form a solid, and then pulverize to obtain the final product.

6. The preparation method according to claim 5, characterized in that, Based on the mass of the oil powder, the mass percentage of each component is as follows: In S2, yeast dietary fiber is 6%, modified yeast protein obtained from S1 is 6%, and water is 53%. In S3, there is 32% vegetable oil and 3% emulsifier. The vegetable oil in S3 is selected from any one of flaxseed oil, rice bran oil, and olive oil.

7. The application of the microcapsule oil powder prepared by the method according to any one of claims 5 to 6 in bread preparation.

8. The application as described in claim 7, characterized in that, The microcapsule oil powder is used to improve the specific volume and texture of bread.

9. A type of bread that does not contain butter, characterized in that, Microencapsulated fat powder prepared using yeast dietary fiber and modified yeast protein powder as wall materials is used to replace butter.

10. The bread as described in claim 9, characterized in that, By weight, it includes 150-300 parts high-gluten flour, 5-20 parts white sugar, 1-3 parts edible salt, 2.5-5 parts dry yeast, 3-10 parts microcapsule oil powder, and 50-150 parts water.

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