Lactobacillus plantarum powder, preparation method and application thereof
By using resistant starch and whey protein as protective carriers, combined with heat-resistant protectants, the problem of low probiotic survival rate in spray drying was solved, and a *Lactobacillus plantarum* powder with high viable count and good powder properties was prepared. It is suitable for fermented foods such as yogurt and maintains stability in acidic environments.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- ACADEMY OF PLANNING & DESIGNING OF THE MINIST OF AGRI
- Filing Date
- 2023-02-02
- Publication Date
- 2026-05-26
AI Technical Summary
In existing technologies, spray drying has the problem of low bacterial survival rate in the preparation of probiotic powder, especially at high airflow temperatures. Improving the survival rate of probiotics and their stability in acidic environments is crucial.
Using resistant starch and whey protein as protective carriers, combined with heat-protective agents such as trehalose, Lactobacillus plantarum powder was prepared by spray drying to form a dense protective body, reducing the damage of high-temperature airflow to the bacteria and maintaining a high viable count in an acidic environment.
It achieves high viable count and low moisture content of Lactobacillus plantarum powder during spray drying, possesses good powder properties, can be used in foods such as yogurt, and maintains a high viable count in the digestive system to reach the colon, with a theoretical shelf life of 233 days.
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Figure CN116004477B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of probiotic powder technology, specifically relating to a Lactobacillus plantarum powder, its preparation method, and its application. Background Technology
[0002] In recent years, the beneficial effects of probiotics have been increasingly confirmed, and the global scientific and industrial communities have reached a consensus on the role of probiotics in regulating human health, making probiotics a focus of attention. Currently, the downstream products of the probiotic industry span multiple fields such as fermented dairy products, dairy beverages, snacks, dietary supplements, daily chemical products, and animal feed, with a wide variety of product categories. These can be mainly divided into three categories: probiotic functional foods (85.9%), health foods and pharmaceuticals (8.6%), and probiotic raw materials (5.6%).
[0003] Leveraging the beneficial functions of probiotics, the ultimate goal of probiotic research is to develop products that regulate bodily functions and promote human health. Incorporating probiotics into shelf-stable foods and beverages is a significant innovation. The beneficial effects of probiotics are closely related to daily intake; studies have reported that a higher viable count of probiotics in the gut is associated with better results. 6 -10 7 Probiotics can only exert their beneficial effects when their concentration reaches CFU / mL. However, probiotics have extremely demanding requirements for their survival environment. Heat stress during processing and storage, pH and enzyme stress in the digestive system during consumption, and many other adverse factors can lead to varying degrees of activity loss, severely restricting their application and development. Therefore, probiotic cell preservation technology has become a focus of industry attention. Currently, the most common preservation method is to encapsulate and stabilize probiotics before drying them into powder. While freeze-drying, as the most commonly used drying technique, can maximize cell activity preservation, its production process is time-consuming and costly, making it the most energy-intensive step in probiotic powder preparation, and it cannot be done continuously. In comparison, spray drying has the advantages of continuous production, strong processing capacity, and low cost, and is widely used in the food industry. However, its high airflow temperature and rapid dehydration process can easily cause probiotic inactivation. Improving the cell survival rate of spray-dried probiotic powder is crucial. Designing a reasonable probiotic protection carrier and selecting appropriate spray drying parameters are strategies to improve the cell survival rate of probiotics during spray drying.
[0004] For example, the invention patent CN 11514112 A, entitled "A Method for Preparing Enteric-Coated Composite Microcapsules Using Spray Drying Technology," specifically discloses a method suitable for encapsulating solid drug powders such as probiotics or diclofenac sodium. It uses natural polymer materials such as casein and collagen as the wall material for enteric-coated microcapsules, and prepares uniformly sized enteric-coated composite microcapsules at room temperature using a combination of coagulation and spray drying. This method requires the particle size of the probiotic solution system to be ≤500μm. However, the wall materials used, such as xanthan gum, pectin, and gelatin, are not easily soluble or have low solubility at room temperature, making it difficult to guarantee their solubility after simple mixing with the protein solution. Summary of the Invention
[0005] To address the aforementioned shortcomings in existing technologies, the present invention aims to provide a *Lactobacillus plantarum* bacterial powder, its preparation method, and its applications. This method utilizes the advantages of resistant starch—its high gelatinization temperature, stable crystal structure, and prebiotic properties—combined with the excellent gel-forming properties of whey protein, and supplemented with a heat-resistant protectant. These three elements are well coupled to form a good heat-resistant carrier for probiotics, enabling *Lactobacillus plantarum* cells to maintain good viability during spray drying. The resulting *Lactobacillus plantarum* bacterial powder has a high viable count and low moisture content, meeting relevant standards for probiotic foods. It also possesses good sensory characteristics and powder properties, allowing for direct consumption by reconstitution with warm water. Furthermore, this bacterial powder exhibits a high cell survival rate in acidic environments and can be added to foods such as yogurt. The powder also demonstrates good digestive system tolerance, enabling a sufficient number of live bacteria to reach the colon.
[0006] To achieve the above-mentioned objectives, the technical solution adopted by this invention is as follows:
[0007] In a first aspect, a *Lactobacillus plantarum* powder is provided. The wall material of the powder includes resistant starch, whey protein, and a heat protectant. The bacterial cells of the powder are *Lactobacillus plantarum* TH103. The TH103 strain has been disclosed in Chinese invention patent application number 201510385613.6 (A *Lactobacillus plantarum* TH103 and its uses), with accession number CGMCC10739.
[0008] The mass percentages of resistant starch, whey protein, and heat protectant are 7-23%, of which the total mass percentages of resistant starch and whey protein are 3-15%, and the mass percentages of heat protectant are 4-8%; the viable count of the bacterial culture powder is (3.5-9.0) × 10⁻¹⁰. 9 CFU / g, moisture content 5~7%.
[0009] Furthermore, the resistant starch is RS2, RS3, or RS4, preferably RS3; the heat protectant is sucrose or trehalose, preferably trehalose;
[0010] Furthermore, the mass ratio of resistant starch to whey protein is 1:3 to 1:9.
[0011] Secondly, a method for preparing Lactobacillus plantarum powder is provided, the method comprising the following steps:
[0012] (1) Cultivate activated Lactobacillus plantarum TH103 at an inoculation rate of 1%, and after culturing for 12 hours, centrifuge the bacterial solution at low temperature, wash the bacterial cells with physiological saline, and obtain concentrated Lactobacillus plantarum suspension for later use.
[0013] (2) The resistant starch aqueous solution was boiled for 10 min and then cooled to room temperature to obtain solution A;
[0014] (3) Mix whey protein aqueous solution with heat protectant, treat in a 60°C water bath for 30 min, and cool to room temperature to obtain solution B;
[0015] (4) After thoroughly mixing solution A and solution B, add the concentrated Lactobacillus plantarum suspension obtained in step (1) and mix evenly to obtain Lactobacillus plantarum bacterial solution;
[0016] (5) The *Lactobacillus plantarum* bacterial solution obtained in step (4) is spray-dried while being stirred to obtain *Lactobacillus plantarum* bacterial powder. The inlet air temperature for spray drying is 100-140℃, the inlet air volume is 30%-70%, and the feed flow rate is 5-10 mL / min.
[0017] Further, in step (1), the activated Lactobacillus plantarum TH103 was obtained by slowly thawing the frozen Lactobacillus plantarum TH103 under an environment of about 37°C, streaking it in MRS solid medium for 24 hours, then picking well-shaped colonies from the plate and inoculating them into MRS liquid medium. After culturing at about 37°C for 24 hours, a seed culture was obtained. The seed culture was inoculated into MRS liquid medium at a ratio of 1%, and the cells were collected by centrifugation after 12 hours. The cells were washed and suspended with sterile physiological saline to obtain a concentrated Lactobacillus plantarum suspension with a concentration of 10 times.
[0018] Further, in step (2), resistant starch is first added to sterilized deionized water, stirred evenly, and then treated in a boiling water bath for 10 minutes before cooling to room temperature for later use; the concentration of resistant starch is 0.3-3.75%.
[0019] Further, in step (3), whey protein is first added to sterilized deionized water and fully hydrated overnight at 4°C. Then, a certain proportion of heat protectant is added to the hydrated whey protein solution, stirred evenly, and treated in a 60°C water bath for 30 min. The solution is then cooled to room temperature for later use. The concentration of the whey protein solution is 2.25-13.5%, and the amount of heat protectant added is 4-8%.
[0020] Further, in step (4), the obtained Lactobacillus plantarum powder is collected and stored at 4°C for later use.
[0021] Thirdly, an application of Lactobacillus plantarum powder is provided, which can be directly brewed as a powder or used in fermented foods such as yogurt.
[0022] The beneficial effects of this invention are as follows:
[0023] (1) This invention uses resistant starch and whey protein as protective carriers, supplemented with heat-resistant protective agents, to achieve the preparation of *Lactobacillus plantarum* powder by spray drying. The obtained *Lactobacillus plantarum* powder has a viable count and moisture content that meet the relevant requirements for probiotic foods, and has good powder properties. It can be directly prepared as a powder or applied to fermented foods such as yogurt. It is recommended that this powder be refrigerated or frozen, with a theoretical shelf life of 233 days at 4°C.
[0024] (2) The high gelatinization temperature of resistant starch and the good film-forming and gelling properties of whey protein together form a relatively dense and thick protective body around the bacteria, reducing the damage to the bacteria caused by the high-temperature airflow during spray drying; at the same time, the enzyme resistance and prebiotic properties of resistant starch enable the obtained Lactobacillus plantarum powder to pass smoothly through the gastrointestinal digestive system and reach the colon with a high number of live bacteria; furthermore, the unfolding of peptide chains after protein denaturation exposes the active groups inside the molecules, giving the powder better brewing properties. Attached Figure Description
[0025] Figure 1 This is a schematic diagram of the surface structure of Lactobacillus plantarum powder provided in an embodiment of the present invention;
[0026] Figure 2 A schematic diagram of the cross-sectional structure of Lactobacillus plantarum powder provided in an embodiment of the present invention;
[0027] Figure 3 The brewing characteristics and effects of Lactobacillus plantarum powder provided in the embodiments of the present invention are shown in the figure.
[0028] Figure 4 A curve showing the change in the number of viable bacteria in yogurt provided in an embodiment of the present invention using Lactobacillus plantarum powder;
[0029] Figure 5 This is a schematic diagram illustrating the digestive system release characteristics of Lactobacillus plantarum powder provided in an embodiment of the present invention. Detailed Implementation
[0030] The specific embodiments of the present invention are described below to enable those skilled in the art to understand the present invention. However, it should be understood that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, various changes are obvious as long as they are within the spirit and scope of the present invention as defined and determined by the appended claims. All inventions utilizing the concept of the present invention are protected.
[0031] The MRS liquid culture medium used in the following examples can be purchased commercially; all raw materials are food-grade, non-toxic, and safe and nutritious for consumption.
[0032] Example 1 uses resistant starch RS3, whey protein, and trehalose as protective carriers.
[0033] (1) Preparation of concentrated Lactobacillus plantarum culture: The frozen TH103 was slowly thawed at 37°C, and then the culture was inoculated into 100 mL of MRS liquid medium in a clean bench and cultured at 37°C for 12 h in a constant temperature and humidity chamber. Then, a single colony was picked and inoculated into 100 mL of liquid medium and cultured at 37°C and 150 r / min for 24 h to obtain activated Lactobacillus plantarum. The activated Lactobacillus plantarum was inoculated into MRS liquid medium at a volume ratio of 1%, placed in a constant temperature and humidity chamber, cultured at 37°C for 12 h, centrifuged at 4000 r / min for 15 min to collect the cells, washed once with physiological saline, and then resuspended in 10 mL of sterile physiological saline.
[0034] (2) Weigh 3.33g of RS3 resistant starch and add it to 50mL of sterile water. Shake well, place it in a boiling water bath for 10min, and then cool it to room temperature for later use.
[0035] (3) Weigh 16.67g of whey protein and add it to 150mL of sterile water. Stir to dissolve and place in a 4℃ refrigerator overnight. After fully hydrating, add 12g of trehalose and stir for 10min. Then place the whey protein-trehalose mixture in a 60℃ water bath for 30min and then cool to room temperature.
[0036] (4) Mix the cooled RS3 resistant starch solution with whey protein-trehalose solution, stir evenly, add concentrated Lactobacillus plantarum solution and stir.
[0037] (5) The above mixed bacterial solution was spray-dried with an inlet air temperature of 120℃, an inlet air volume of 30%, and a material flow rate of 7mL / min to obtain a milky white Lactobacillus plantarum powder with a viable count of approximately 8.93×10⁻⁶. 9 CFU / g, moisture content is approximately 6.2%.
[0038] Example 2: Using resistant starch RS2, whey protein, and trehalose as protective carriers
[0039] Weigh 3.33g of RS2 resistant starch and add it to 50mL of sterile water. Shake well, place in a boiling water bath for 10min, and then cool to room temperature for later use.
[0040] Other preparation methods are the same as in Example 1 above. A milky-white *Lactobacillus plantarum* powder was obtained, with a viable count of approximately 8.46 × 10⁻⁶. 9 CFU / g, moisture content is approximately 6.26%.
[0041] Example 3: Using resistant starch RS4, whey protein, and trehalose as protective carriers
[0042] Weigh 3.33g of RS4 resistant starch and add it to 50mL of sterile water. Shake well, place in a boiling water bath for 10min, and then cool to room temperature for later use.
[0043] Other preparation methods are the same as in Example 1 above. A milky-white *Lactobacillus plantarum* powder was obtained, with a viable count of approximately 8.52 × 10⁻⁶. 9 CFU / g, moisture content is approximately 6.31%.
[0044] Example 4: Using resistant starch RS3, whey protein, and trehalose as protective carriers
[0045] The specific preparation method is the same as in Example 1, but the content and ratio of resistant starch RS3 and whey protein protective carrier are changed. Specifically, the total mass percentage of resistant starch RS3 and whey protein is 3%, and the ratio of resistant starch to whey protein is 1:9. The resulting *Lactobacillus plantarum* powder has a viable cell count of approximately 6.74 × 10⁻⁶. 9 CFU / g, moisture content is approximately 6.4%.
[0046] Example 5: Using resistant starch RS3, whey protein, and trehalose as protective carriers
[0047] The specific preparation method is the same as in Example 1, but the content and ratio of resistant starch RS3 and whey protein protective carrier are changed. Specifically, the total mass percentage of resistant starch RS3 and whey protein is 15%, and the ratio of resistant starch to whey protein is 1:3. The resulting *Lactobacillus plantarum* powder has a viable cell count of approximately 3.52 × 10⁻⁶. 9 CFU / g, moisture content is approximately 6.18%.
[0048] In addition, other specific embodiments include the combination of resistant starch RS2, RS3, whey protein and other heat-resistant drying protectants such as sucrose, and are not limited to the examples listed above.
[0049] Example 6
[0050] The *Lactobacillus plantarum* powder prepared in the above examples was evaluated according to the following methods:
[0051] 1. Determination of particle size, powder properties and microstructure of Lactobacillus plantarum powder
[0052] 1.1 The particle size distribution of the *Lactobacillus plantarum* powder obtained in Example 1 was analyzed using a wet method with Mastersizer 2000 dynamic light scattering; the angle of repose of the powder was also measured. The results are as follows:
[0053]
[0054] The results show that the Lactobacillus plantarum powder obtained by this invention has a small particle size and good powder flowability (angle of repose < 40°).
[0055] 1.2 The *Lactobacillus plantarum* powder obtained in the above embodiments was surface-sprayed with gold, and its surface morphology was observed using an SU8020 field emission scanning electron microscope. Figure 1 As shown; next, the mycelium powder was resin-embedded and sectioned, and then its cross-section was observed to further understand the internal structure of the mycelium powder, such as... Figure 2 As shown.
[0056] Depend on Figure 1 It can be seen that the Lactobacillus plantarum TH103 bacterial powder obtained by spray drying is microscopically composed of spherical particles with an intact overall structure, surface wrinkles and dents but no cracks, and no probiotic residues; further, considering the internal structure of the bacterial powder, namely Figure 2 It can be seen that after the TH103 bacteria and the wall material are mixed together, they are encapsulated in the protective wall material, thus forming a complete bacterial powder.
[0057] 2. Investigation into the optimal brewing temperature of Lactobacillus plantarum powder
[0058] The optimal brewing temperature of the *Lactobacillus plantarum* powder obtained in Examples 1, 2, and 3 above was studied. Ice water at 4℃, room temperature water, warm water at 40℃, hot water at 75℃, and boiling water were selected as brewing temperatures. 0.5g of *Lactobacillus plantarum* powder was weighed and quickly added to Erlenmeyer flasks containing 50mL of sterile water at different temperatures. After slowly shaking for 15 minutes on a shaker, 1mL of the brewed solution was taken for decapsulation treatment, followed by plate counting, with the initial viable count of *Lactobacillus plantarum* powder serving as a control.
[0059] After testing, the number of viable bacteria in Lactobacillus plantarum powder after being dissolved in water at different temperatures was as follows: Figure 3 As shown. By Figure 3 It can be seen that the viable bacteria count of the three types of Lactobacillus plantarum powder decreased to 10 after being brewed with boiling water. 7 Compared to the previous method, although the number of live bacteria remained at 10 after being brewed with 75℃ water, the result was different.7 The number of probiotics is around 75°C, but this is two orders of magnitude lower than the original *Lactobacillus plantarum* powder. Correspondingly, brewing with water at other temperatures can maintain a relatively high number of probiotics. Therefore, if intended as a ready-to-drink product, a brewing temperature below 75°C is recommended. Furthermore, blending with other fruit and vegetable powders can create different flavors of *Lactobacillus plantarum* powder.
[0060] 3. Application of Lactobacillus plantarum powder in yogurt
[0061] The *Lactobacillus plantarum* powder obtained in Examples 1, 2, and 3 above was added to yogurt. Specifically, 1g of *Lactobacillus plantarum* powder was weighed and placed in 100g of yogurt and stored for 21 days. On days 0, 2, 5, 10, 15, and 21, viable cell counts were performed on plates. An equal amount of naked *Lactobacillus plantarum* culture was directly added to 100g of yogurt as a control.
[0062] The change curve of viable bacteria count of Lactobacillus plantarum powder during the shelf life of yogurt was determined as follows: Figure 4 As shown. By Figure 4 It can be seen that the number of viable bacteria in the group with directly added *Lactobacillus plantarum* cells (i.e., the naked bacteria group) decreased to the order of 6.7 after day 7, and no viable bacteria were detected after day 21. While the viable bacteria counts of the three *Lactobacillus plantarum* powders all showed a certain downward trend during the shelf life of yogurt (4˚C, 21 days), the viable bacteria counts remained at the order of 9 after 21 days of storage. Comparing the survival of *Lactobacillus plantarum* powders in the yogurt system of Examples 1, 2, and 3, it can be found that the *Lactobacillus plantarum* powder of Example 1 had the highest number of viable bacteria during the shelf life, but there was no significant difference compared with the other two *Lactobacillus plantarum* powders. Therefore, the *Lactobacillus plantarum* powder obtained by this invention can effectively improve the survival ability of probiotic cells in fermented foods such as yogurt.
[0063] 4. Digestive system release characteristics of Lactobacillus plantarum powder
[0064] The *Lactobacillus plantarum* powder obtained in Examples 1, 2, and 3 was used to study the continuous release characteristics in a digestive system. Specifically, 0.5 g of *Lactobacillus plantarum* powder was added to 20 mL of simulated gastric juice (pH 2.0, containing pepsin), and treated with a constant temperature water bath at 37°C and 130 rpm for 2 hours. Samples were taken every 0.5 hours (0.5h, 1h, and 2h) for viable cell counts on platelets. Then, the pH of the treated gastric juice was adjusted to 7.2, and 10 mL was added to 10 mL of intestinal juice (pH 7.4, containing pancreatic enzymes), and treated with a constant temperature water bath at 37°C and 130 rpm for 4 hours. Samples were taken every hour for viable cell counts on platelets. Finally, 10 mL of the treated intestinal juice was added to 10 mL of simulated colonic juice (0.1 mL) and treated for 2 hours. Samples were taken every hour for direct plate counts. The results were compared with those of *Lactobacillus plantarum* cells (naked bacteria group).
[0065] The survival rate of *Lactobacillus plantarum* powder in a simulated digestive system was measured as follows: Figure 5 As shown. By Figure 5 It was observed that the bacteria in the naked bacterial group were rapidly inactivated upon entering the simulated gastric fluid, and no viable bacteria could be detected after 1 hour, indicating that the probiotic bacteria could not survive in the simulated gastric fluid environment. In contrast, the *Lactobacillus plantarum* powder obtained in this invention maintained a viable count of 9 orders of magnitude throughout the simulated digestion process. Specifically, the viable count of the *Lactobacillus plantarum* powder gradually decreased over time during simulated gastric fluid treatment, but the decrease was less than 1 order of magnitude after 2 hours, indicating that the *Lactobacillus plantarum* powder has good resistance to gastric acid, meaning the powder provides necessary protection for *Lactobacillus plantarum*. At this point, the microstructure of the powder showed some damage, exposing a certain amount of probiotic bacteria. Subsequently, in simulated intestinal and colonic fluids, the viable count of the *Lactobacillus plantarum* powder remained relatively stable without a significant decrease in order of magnitude. After 2 hours of colonic fluid treatment, the viable count of all three *Lactobacillus plantarum* powders was above 7.5 orders of magnitude, indicating that the *Lactobacillus plantarum* powder has good digestive system release characteristics and stability, maintaining a large number of viable bacteria in the intestine and colon.
[0066] 5. Accelerated Storage Experiment of Lactobacillus plantarum Probiotic Powder
[0067] Taking the Lactobacillus plantarum powder of Example 1 as an example, an accelerated storage experiment was conducted. A certain amount of Lactobacillus plantarum powder was placed in environmental conditions of 50℃, 60℃, 70℃, and 80℃, and samples were taken at 2h, 4h, 6h, 8h, 10h, and 12h for decapsulation plate counting. The inactivation rate constant of Lactobacillus plantarum powder under each temperature condition was obtained according to the Arrhenius equation, and the theoretical shelf life of Lactobacillus plantarum powder was estimated accordingly.
[0068] The inactivation rate of Lactobacillus plantarum powder was determined and is shown in the table below:
[0069]
[0070] Based on this, the theoretical shelf life of the Lactobacillus plantarum powder obtained by the present invention is calculated to be 233 days at 4°C.
[0071] This invention utilizes resistant starch and whey protein as protective carriers, supplemented with heat-resistant agents, to achieve the preparation of *Lactobacillus plantarum* powder via spray drying. The obtained *Lactobacillus plantarum* powder meets the relevant requirements for probiotic foods in terms of viable cell count and moisture content, and possesses excellent powder properties, allowing for direct reconstitution or application in fermented foods such as yogurt. Refrigeration or freezing is recommended for storage; the theoretical shelf life at 4°C is 233 days.
[0072] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.
[0073] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.
Claims
1. A Lactobacillus plantarum powder, characterized in that, The cell wall material of the bacterial powder is composed of resistant starch, whey protein, and a heat protectant; the resistant starch is RS2, RS3, or RS4; the heat protectant is sucrose or trehalose; the bacterial cells of the bacterial powder are *Lactobacillus plantarum* TH103, with the preservation number CGMCC10739; the viable count of the bacterial powder is (3.5-9.0) × 10⁻⁶. 9 CFU / g, moisture content 5~7%; In the wall material solution system before spray drying of the prepared microbial powder, the total mass-volume percentage of the resistant starch, whey protein and heat protectant is 7~23 g / 100 mL, wherein the total mass-volume percentage of the resistant starch and whey protein is 3~15 g / 100 mL, and the mass-volume percentage of the heat protectant is 4~8 g / 100 mL; and the mass ratio of the resistant starch to the whey protein is 1:3-1:
9.
2. The *Lactobacillus plantarum* powder according to claim 1, characterized in that, The resistant starch is RS3; the heat protectant is trehalose.
3. A method for preparing *Lactobacillus plantarum* powder according to any one of claims 1-2, characterized in that, Includes the following steps: (1) Cultivate activated Lactobacillus plantarum TH103 at an inoculation rate of 1%, and after culturing for 12 hours, centrifuge the bacterial solution at low temperature, wash the bacterial cells with physiological saline, and obtain concentrated Lactobacillus plantarum suspension for later use. (2) The resistant starch aqueous solution was boiled for 10 min and then cooled to room temperature to obtain solution A; (3) Mix whey protein aqueous solution with heat protectant, treat in a 60°C water bath for 30 min, and cool to room temperature to obtain solution B; (4) After thoroughly mixing solution A and solution B, add the concentrated Lactobacillus plantarum suspension obtained in step (1) and mix evenly to obtain Lactobacillus plantarum bacterial solution; (5) The Lactobacillus plantarum liquid obtained in step (4) is spray-dried while stirring to obtain Lactobacillus plantarum powder.
4. The method for preparing Lactobacillus plantarum powder according to claim 3, characterized in that, In step (5), the inlet air temperature of the spray dryer is 100-140℃, the inlet air volume is 30%-70%, and the feed flow rate is 5-10mL / min.
5. The application of the *Lactobacillus plantarum* powder according to any one of claims 1-2, characterized in that, The bacterial powder can be directly brewed as a powder or used in fermented foods.