A broadleaf hand dietary fiber yogurt and a preparation method and application thereof

Abstract

The present application belongs to the technical field of yogurt preparation. More specifically, it relates to a kind of broadleaf hand dietary fiber yogurt and its preparation method and application. The present application introduces broadleaf hand dietary fiber into yogurt matrix before fermentation, and successfully prepares broadleaf hand dietary fiber yogurt with significant lipid-lowering function by optimizing co-fermentation process parameters. The present application innovatively introduces broadleaf hand dietary fiber into the yogurt co-fermentation system, and simultaneously realizes texture improvement, flavor optimization and weight loss and lipid-lowering function enhancement under the premise of zero addition of exogenous stabilizer and flavor modifier, significantly improving the overall quality of the product. The present application expands the high-value utilization path of broadleaf hand resources in the field of functional foods, develops natural functional dairy products with weight loss and lipid-lowering effect, meets the current market demand of consumers for healthy, natural and functional foods, and has good application prospect and application value.

Description

Technical Field

[0001] This invention belongs to the field of yogurt preparation technology. More specifically, it relates to a yogurt made with broad bean dietary fiber, its preparation method, and its application. Background Technology

[0002] Yogurt is a traditional fermented dairy product made from raw milk through lactic acid bacteria fermentation. It is highly favored by consumers due to its rich nutritional value and probiotic benefits. With the popularization of health-conscious consumption, market demand for yogurt has shifted from basic nutritional functions to "zero additives" and functional benefits. Developing new types of yogurt that use natural active ingredients to replace food additives has become an industry trend. Dietary fiber, as the "seventh essential nutrient," can improve the texture and provide health benefits when added to yogurt. However, current technologies mostly use dietary fiber derived from resistant dextrin, inulin, etc., which have limited functional activity and suffer from severe homogenization.

[0003] Buddha's Hand ( Citrus medica L. var. sarcodactylis Citrus sempervirens (Citrus medica) is a plant belonging to the Rutaceae family and the Citrus genus. It has traditional medicinal properties such as regulating qi, soothing the liver, and relieving stomach pain. Among them, Guangfo Shou (Citrus medica var. sarcodactylis), a native medicinal herb of Guangdong Province, has been listed in the "Guangdong Provincial Regulations on the Protection of Lingnan Medicinal Herbs." It is rich in resources and has high development and utilization value. Studies have shown that the dietary fiber content of dried Citrus medica fruit is as high as about 45%. However, its current applications are mainly concentrated in medicinal extraction or flavoring preparation, and the high-value utilization of dietary fiber in the functional food field has not been fully developed. More importantly, Citrus medica raw materials contain bitter substances such as limonene and naringin. If the amount added is not properly controlled, it can easily introduce obvious unpleasant flavors, leading to a decrease in the sensory acceptance of the product; while if the amount added is too low, it is difficult to exert its functional activity, making it difficult to achieve a balance between texture improvement, flavor harmony, and functional enhancement.

[0004] Therefore, there is an urgent need to develop a zero-additive functional yogurt preparation technology that uses the dietary fiber of Guangfo Shou as a functional factor. Under the premise of precise control of the amount added and fermentation process, it is necessary to simultaneously optimize the texture properties, improve the sensory quality and enhance the weight loss and lipid reduction functions, so as to provide a new way for the high-value utilization of Guangfo Shou resources. Summary of the Invention

[0005] The present invention aims to overcome the defects and deficiencies in the prior art and provide a yogurt with Guangfo Shou dietary fiber as a functional factor and its preparation method.

[0006] The first objective of this invention is to provide the application of the dietary fiber of *Gnaphalium affine* in the preparation of weight-loss and lipid-lowering yogurt.

[0007] A second objective of this invention is to provide the application of *Gynostemma pentaphyllum* dietary fiber in the preparation of yogurt that helps control body fat, or in the preparation of yogurt that helps maintain healthy blood lipid levels.

[0008] The third objective of this invention is to provide a method for preparing yogurt containing ginseng and ginseng dietary fiber.

[0009] The fourth objective of this invention is to provide a method for preparing yogurt containing the dietary fiber of *Gynostemma pentaphyllum* using the above-described preparation method.

[0010] The fifth objective of this invention is to provide the application of the above-mentioned Guangfo Shou dietary fiber yogurt in the preparation of weight loss and / or lipid-lowering products.

[0011] The above-mentioned objective of this invention is achieved through the following technical solution:

[0012] This invention provides the application of dietary fiber from *Gnaphalium affine* in the preparation of weight-loss and lipid-lowering yogurt.

[0013] Specifically, the weight loss refers to reducing body weight and reducing body fat accumulation, and the lipid reduction includes lowering serum triglyceride (TG), total cholesterol (TC), and low-density lipoprotein cholesterol (LDL-C) levels, as well as increasing high-density lipoprotein cholesterol (HDL-C) levels.

[0014] This invention provides the application of bergamot dietary fiber in the preparation of yogurt that helps control body fat.

[0015] This invention provides the application of bergamot dietary fiber in the preparation of yogurt that helps maintain healthy blood lipid levels.

[0016] This invention provides a method for preparing yogurt with Guangfo Hand dietary fiber, which involves adding Guangfo Hand dietary fiber to the yogurt fermentation raw materials.

[0017] Preferably, the amount of dietary fiber added is 13~21 mg / mL.

[0018] More preferably, the amount of dietary fiber added is 17-19 mg / mL.

[0019] More preferably, the amount of dietary fiber added is 17.5 mg / mL.

[0020] As an alternative implementation, the starter culture for the aforementioned yogurt contains Streptococcus thermophilus (Streptococcus thermophilus). Streptococcus thermophiles Lactobacillus bulgaricus ( Lactobacillus bulgaricus Bifidobacterium bifidum ( Bifidobacterium bifidum Bifidobacterium animalis ( Bifidobacterium animalis Bifidobacterium longum ( Bifidobacterium longum ), Lactobacillus acidophilus ( Lactobacillus acidophilus Lactobacillus casei ( Lactobacillus casei One or more of the following.

[0021] Preferably, the starter culture for yogurt consists of Streptococcus thermophiles, Lactobacillus bulgaricus, Bifidobacterium bifidum, Bifidobacterium animalis, Bifidobacterium longum, Lactobacillus acidophilus, and Lactobacillus casei.

[0022] As an alternative specific implementation, the starter is yogurt starter (L903) from Chr. Hansen (China) Ltd., Denmark.

[0023] Preferably, the amount of the fermenting agent added is 0.04~0.07 g / L.

[0024] More preferably, the amount of the fermenting agent added is 0.05~0.07 g / L.

[0025] More preferably, the amount of the fermenting agent added is 0.05 g / L.

[0026] As an optional specific implementation, the method for preparing the Guangfo Hand dietary fiber yogurt includes the following yogurt fermentation raw materials: Guangfo Hand dietary fiber with a concentration of 13~21 mg / mL, 0.04~0.07 g / L starter culture, 90~150 mg / mL sweetener, and the remainder being raw milk; the raw milk is one or more of raw milk, pure milk, and reconstituted milk.

[0027] The pure milk can be whole milk, low-fat milk, or skim milk.

[0028] The sweetener may be sucrose, white sugar, etc.

[0029] Preferably, in the above preparation method, the fermentation conditions for yogurt are fermentation at 41~44℃ for 3~6 h.

[0030] More preferably, the yogurt is fermented at 42-43°C for 4 hours.

[0031] More preferably, the yogurt is fermented at 42°C for 4 hours.

[0032] As an alternative implementation, the post-ripening treatment of the yogurt is to refrigerate it at 2~8 ℃ for 12~36 h.

[0033] Optionally, the post-ripening treatment of the yogurt is to refrigerate it at 4°C for 24 hours.

[0034] As an alternative implementation, the method for preparing Guangfoshou dietary fiber yogurt involves adding 13-21 mg / mL of Guangfoshou dietary fiber and 90-150 mg / mL of sugar to milk, mixing them evenly to obtain a mixed emulsion, sterilizing the mixed emulsion, inoculating it with a starter culture under sterile conditions, and then performing a post-fermentation treatment after fermentation to obtain Guangfoshou dietary fiber yogurt.

[0035] As an alternative implementation, the sugar is sucrose.

[0036] Preferably, the final concentration of sucrose in the mixed emulsion is 110 mg / mL.

[0037] Preferably, the final concentration of the dietary fiber from *Gnaphalium affine* in the mixed emulsion is 17-19 mg / mL.

[0038] More preferably, the final concentration of the dietary fiber of *Gynostemma pentaphyllum* in the mixed emulsion is 17.5 mg / mL.

[0039] Preferably, the fermentation is carried out at 41-44°C for 3-6 hours.

[0040] More preferably, the fermentation is carried out at 42°C for 4 hours.

[0041] Optionally, the post-ripening treatment is to refrigerate at 2-8 ℃ for 12-36 h.

[0042] Optionally, the post-ripening treatment is refrigeration at 4 ℃ for 24 h.

[0043] As a preferred embodiment, the preparation method of the Guangfoshou dietary fiber yogurt is as follows: milk, Guangfoshou dietary fiber and sugar are mixed to obtain a mixed emulsion. The mixed emulsion is sterilized, cooled and inoculated with a starter culture. After fermentation at 42°C for 4 hours, it is taken out and demulsified. The mixed emulsion after demulsification is resealed and placed in a refrigerator at 4°C for 24 hours for post-ripening treatment to obtain Guangfoshou dietary fiber yogurt.

[0044] Preferably, the demulsification process is a stirring demulsification process.

[0045] As an alternative implementation, the sterilization is performed using pasteurization.

[0046] As an alternative implementation, the sterilization is performed at 93-97 °C for 3-7 min.

[0047] As an alternative implementation, the sterilization is performed at 95°C for 5 minutes.

[0048] The Guangfo Shou dietary fiber yogurt prepared by the above method should also be within the scope of protection of this invention.

[0049] This invention further demonstrates through animal experiments that the Guangfo Shou dietary fiber yogurt can significantly reduce weight gain and body fat accumulation in rats, improve lipid metabolism, and achieve weight loss. In a mixed hyperlipidemia model, the yogurt can effectively reduce serum triglyceride, total cholesterol, and low-density lipoprotein cholesterol levels, while increasing high-density lipoprotein cholesterol levels, thus comprehensively improving lipid metabolism disorders.

[0050] Therefore, the present invention also provides the application of the above-mentioned Guangfo Shou dietary fiber yogurt in the preparation of weight loss and / or lipid-lowering products.

[0051] Specifically, the lipid-lowering refers to lowering blood lipids.

[0052] Specifically, the product is a health food that helps with weight loss and / or helps maintain healthy blood lipid levels.

[0053] The present invention has the following beneficial effects: This invention introduces the dietary fiber of *Gnaphalium affine* into the yogurt matrix before fermentation. By optimizing the co-fermentation process parameters, a yogurt with significant lipid-lowering function made from *Gnaphalium affine* dietary fiber was successfully prepared. The *Gnaphalium affine* dietary fiber yogurt of this invention exhibits significant inhibitory activity against pancreatic lipase, with a significantly better inhibitory effect than yogurt prepared using resistant dextrin and pumpkin seed dietary fiber. Particularly noteworthy is its significantly superior inhibitory activity compared to samples where the same dietary fiber was added via post-fermentation physical mixing. This demonstrates that the co-fermentation process can promote the synergistic effect between dietary fiber and the yogurt matrix, thereby enhancing its function in inhibiting fat digestion and absorption.

[0054] The introduction of Guangfo Shou dietary fiber significantly strengthens the three-dimensional gel network structure of yogurt, resulting in a marked improvement in the overall texture and physical stability of the yogurt. Furthermore, by precisely controlling the amount of Guangfo Shou dietary fiber added and other fermentation parameters, this invention effectively avoids unpleasant flavors that may be caused by the bitter components of Guangfo Shou, while fully preserving its lipid-lowering function. The Guangfo Shou dietary fiber yogurt of this invention has a uniform and delicate texture, a smooth mouthfeel, and no gritty feeling, exhibiting excellent overall sensory quality.

[0055] Animal experiments further validated the in vivo efficacy of the Guangfo Shou dietary fiber yogurt of this invention. In a high-fat diet-induced obesity model, the yogurt intervention significantly reduced weight gain and body fat accumulation in rats, with the weight loss effect attributed to improved lipid metabolism. In a mixed hyperlipidemia model, the yogurt effectively reduced serum triglyceride, total cholesterol, and low-density lipoprotein cholesterol levels, while increasing high-density lipoprotein cholesterol levels, comprehensively improving lipid metabolism disorders. This provides reliable in vivo experimental evidence for Guangfo Shou dietary fiber yogurt as a functional food for assisting in the regulation of weight and blood lipids.

[0056] This invention innovatively introduces the dietary fiber of *Houttuynia cordata* into a yogurt co-fermentation system. Without adding any exogenous stabilizers or flavor modifiers, it simultaneously achieves textural improvement, flavor optimization, and enhanced weight-loss and lipid-lowering functions, significantly improving the overall quality of the yogurt product. This invention expands the high-value utilization pathway of *Houttuynia cordata* resources in the functional food field, developing natural functional dairy products with weight-loss and lipid-lowering effects. This aligns with current consumer market demands for healthy, natural, and functional foods, and has significant application value. Attached Figure Description

[0057] Figure 1 To improve the water-holding capacity of Guangfo Hand Dietary Fiber Yogurt and Zero Additive Yogurt.

[0058] Figure 2 Figure A shows the rheological properties of Guangfo Shou dietary fiber yogurt and zero-additive yogurt; Figure B shows the shear scan curve of the yogurt.

[0059] Figure 3 Particle size distribution of Guangfo Shou dietary fiber yogurt and additive-free yogurt.

[0060] Figure 4 Figure A shows the infrared spectrum of protein in Guangfo Shou dietary fiber yogurt and zero-additive yogurt; Figure B shows the infrared spectrum of total protein in yogurt.

[0061] Figure 5 The results show the inhibitory activity of yogurt containing dietary fiber from different sources on pancreatic lipase.

[0062] Figure 6 The results show the in vitro pancreatic lipase inhibitory activity assays of different yogurts.

[0063] Figure 7 The effects of different treatments on the body weight of obese rats are shown in Figure A. Figure A shows the changes in body weight of rats in each group of the obese model. Figure B shows the weight gain and final body weight of rats in each group of the obese model.

[0064] Figure 8The effects of different treatments on food intake in obese rat models are shown in Figure A; Figure B shows the changes in food intake in each group of obese rat models and the total food intake and total calorie intake in each group of obese rat models. * indicates a significant difference in total food intake. P <0.05); # indicates a significant difference in total calorie intake ( P <0.05).

[0065] Figure 9 The results show the food utilization rate of obese rat models under different treatments.

[0066] Figure 10 The effects of different treatments on body fat and body fat percentage in obese rats were shown in Figure A. Figure A shows the perirenal fat content of rats in each group of the obese model; Figure B shows the epididymal fat content of rats in each group of the obese model; and Figure C shows the body fat percentage of rats in each group of the obese model.

[0067] Figure 11 The effects of different treatments on blood lipid levels in rats with mixed hyperlipidemia were shown in Figure A. TC content in serum of rats in each group of the mixed hyperlipidemia model was shown in Figure B. TG content in serum of rats in each group of the mixed hyperlipidemia model was shown in Figure C. LDL-C content in serum of rats in each group of the mixed hyperlipidemia model was shown in Figure D. HDL-C content in serum of rats in each group of the mixed hyperlipidemia model was shown in Figure D.

[0068] Figure 12 Figure 1 shows the three-dimensional response surface and contour plots of the effects of various factors on the quality of Guangfo Hand citron dietary fiber yogurt. Figure 2 shows the interaction between the amount of Guangfo Hand citron dietary fiber added and the amount of sucrose added. Figure 3 shows the contour plot of the interaction between the amount of Guangfo Hand citron dietary fiber added and the amount of sucrose added. Figure 4 shows the interaction between the amount of Guangfo Hand citron dietary fiber added and the fermentation time. Figure 5 shows the contour plot of the interaction between the amount of Guangfo Hand citron dietary fiber added and the fermentation time. Figure 6 shows the interaction between the amount of Guangfo Hand citron dietary fiber added and the fermentation time. Figure 7 shows the interaction between the amount of Guangfo Hand citron dietary fiber added and the fermentation time. Figure 8 shows the interaction between the amount of Guangfo Hand citron dietary fiber added and the fermentation time. Figure 9 shows the interaction between the amount of Guangfo Hand citron dietary fiber added and the fermentation time. Detailed Implementation

[0069] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in this technical field.

[0070] Unless otherwise specified, all reagents and materials used in the following examples are commercially available.

[0071] In this example, the commercially available yogurt (CY) is the original flavor yogurt from South China Agricultural University.

[0072] Preparation method of Guangfo Shou powder: After the dried bergamot slices are crushed, the essential oil, flavonoids and polysaccharides are extracted, and then dried, crushed and passed through a 60-mesh sieve to obtain Guangfo Shou powder.

[0073] Preparation method of Guangfo Hand dietary fiber: Guangfo Hand powder was subjected to compound enzymatic hydrolysis using α-amylase and saccharifying enzyme at a material-to-liquid ratio of 1:20 (g / mL) at 60℃ for 120 min, with an enzyme dosage of 396 U / g (enzyme activity ratio of 1:1). Subsequently, alkaline protease hydrolysis was performed at the same material-to-liquid ratio of 1:20 (g / mL), the pH was adjusted to 8.5, and hydrolysis was carried out at 60℃ for 60 min, with an enzyme dosage of 2000 U / g. After enzymatic hydrolysis, the enzyme was inactivated in a 95℃ water bath for 10 min, cooled, centrifuged at 4000 r / min for 15 min, the precipitate was collected and washed three times with distilled water, dried at 60℃ to constant weight, and pulverized through an 80-mesh sieve to obtain Guangfo Hand dietary fiber.

[0074] α-Amylase was purchased from Shanghai Yuanye Biotechnology Co., Ltd.; saccharifying enzyme was purchased from Shanghai Yuanye Biotechnology Co., Ltd.; alkaline protease was purchased from Shanghai Yuanye Biotechnology Co., Ltd.; pure milk was purchased from Inner Mongolia Mengniu Dairy Co., Ltd.; yogurt starter L903 (Lactobacillus delbrueckii subsp. bulgaricus, Streptococcus thermophilus) was purchased from Chr. Hansen (China) Ltd., Denmark; white sugar was repackaged by Taikoo Sugar Co., Ltd. (China); other reagents were commercially available analytical grade; TC reagent kit: Nanjing Jiancheng Bioengineering Institute; TG reagent kit: Nanjing Jiancheng Bioengineering Institute; LDL-C reagent kit: Nanjing Jiancheng Bioengineering Institute; HDL-C reagent kit: Nanjing Jiancheng Bioengineering Institute.

[0075] The textural properties of yogurt were determined according to the reference "ZHAO P, LI N, CHEN L, et al. Effects of Oat β-Glucan on the Textural and Sensory Properties of Low-Fat Set Type PeaProtein Yogurt[J]. Molecules, 2023,28(7): 3067.". A texture analyzer was used, with the measurement mode being Texture Profile Analysis (TPA). The probe model was P / 36R, the pre-measurement speed was 6 mm / s, the mid-measurement speed was 2 mm / s, the post-measurement speed was 2 mm / s, the test displacement was 10 mm, and the applied force was 10 g. The hardness, viscosity, and chewiness of the samples were recorded.

[0076] Determination of yogurt acidity: conducted in accordance with GB 5009 239-2016 "National Food Safety Standard - Determination of Acidity in Food".

[0077] Sensory evaluation of yogurt: Referring to the method in the reference "Zhang Minhua et al. Effects of different functional sugars on the quality and fermentation process of low-temperature stirred yogurt [J]. Food Industry Technology, 2025: 1-11.", an evaluation group of 10 people with sensory evaluation experience was selected to conduct sensory evaluation of dietary fiber yogurt. The specific standards are shown in Table 1.

[0078] Table 1 Sensory Evaluation Table for Yogurt

[0079] Determination of water-holding capacity of yogurt: The method described in the reference "Li Hui, Wu Weidu, Zhu Hui, et al. Study on viscosity and water-holding capacity of stirred yogurt [J]. Grain and Food Industry, 2018, 25(2): 56-59" was used for determination. 15 g of yogurt was weighed into a 50 mL centrifuge tube, centrifuged at 4000 r / min and 4℃ for 15 min, the supernatant was discarded and the weight was measured. The water-holding capacity of yogurt was calculated using the following formula:

[0080] In the formula: WHC represents water holding capacity, %; m2 represents the weight after discarding the supernatant, g; m1 represents the weight of the yogurt and centrifuge tube, g; m represents the weight of the centrifuge tube, g.

[0081] Determination of rheological properties of yogurt: Following the method described in the reference "Hao Shaojie, Zhou Xu, Wang Zihan, et al. Study on quality characteristics and functional activities of lotus leaf yogurt [J]. Food and Fermentation Industries, 2025: 1-11," a rheometer was used for measurement. The gap was 0.05 mm, and the measurement temperature was 25 ℃. The shear frequency was set to 0.1-10 s⁻¹, the frequency scan deformation was set to 0.5%, and the frequency range was 0.1~10 Hz.

[0082] Yogurt particle size determination: Following the method described in the reference "Zhang Lijing, Hua Yufei, Zhang Caimeng, et al. Effects of protein content on texture, rheological properties and microstructure of stirred soybean yogurt [J]. Food Industry Technology, 2024: 122-128," a nano-laser particle size analyzer was used for particle size determination. A yogurt sample solution with a concentration of 1 mg / mL was prepared using PBS. The detection parameters were: particle refractive index 1.450, dispersant refractive index 1.330, and equilibration time 60 s.

[0083] Fourier transform infrared spectroscopy (FTIR) of yogurt was determined according to the method described in the reference "Chang Xulong, Song Zhuomiao, Zhan Zhenming, et al. Effects of flavonoids from *Gynostemma pentaphyllum* on gel properties, antioxidant activity and metabolites of yogurt [J]. Food Industry Technology, 2025: 1-13." Yogurt was directly freeze-dried to obtain yogurt whole protein samples. The yogurt was centrifuged at 5500 r / min for 15 min (4℃), the upper fat layer was discarded, and the pH of the yogurt was adjusted to 4.1. It was then centrifuged at 4000 r / min for 15 min to separate the upper whey layer and the lower protein layer. The lower protein layer was washed three times with an equal volume of buffer (0.1 mmol / L PBS) and centrifuged at 4000 r / min for 15 min. The precipitate was then freeze-dried to obtain yogurt casein samples. 1 mg of the freeze-dried yogurt sample was mixed with dry potassium bromide at a ratio of 1:100, and the infrared spectrum in the range of 4000–400 cm⁻¹ was measured with a resolution of 4 cm⁻¹ and 64 scans.

[0084] Data processing: All sample measurements were repeated three times, and results are expressed as mean difference plus standard deviation. Origin 2024 software was used for graphing, and SPSS 21 was used for significance analysis. P < 0.05 indicated a significant difference (different letters represent significant differences). Design Expert 12 was used for Box-Behnken response surface methodology.

[0085] Example 1: Preparation of Guangfo Shou Dietary Fiber Yogurt Guangfo Hand Dietary Fiber Yogurt (FDFY): 11% (w / w) sucrose and 1.75% (w / w) Guangfo Hand dietary fiber were added to pure milk. After stirring evenly, the mixture was homogenized at 4000 rpm for 5 min, and then pasteurized in a 95℃ water bath for 5 min. After cooling to room temperature, 0.05‰ (w / w) of starter culture L903 was inoculated in a clean bench, and then fermented at 42℃ for 4 h. After fermentation, the mixture was removed and stirred to break the emulsion in a clean bench. The broken emulsion was resealed and refrigerated at 4℃ for 24 h for post-ripening to obtain Guangfo Hand dietary fiber yogurt. The density of pure milk was calculated to be 1.0 g / mL.

[0086] Example 2: Quality Evaluation of Guangfo Hand Dietary Fiber Yogurt Zero-additive yogurt (0Y): 11% (w / w) sucrose was added to pure milk, stirred evenly, homogenized at 4000 rpm for 5 min, and pasteurized in a 95℃ water bath for 5 min. After cooling to room temperature, 0.05‰ (w / w) of starter culture L903 was inoculated in a clean bench, and then fermented at 42℃ for 4 h. After fermentation, the milk was removed and stirred to break the emulsion in a clean bench. The broken emulsion was resealed and refrigerated at 4℃ for 24 h for post-ripening treatment to obtain zero-additive yogurt. Zero-additive yogurt was used as a control.

[0087] I. Texture Characteristics of Yogurt The textural properties of yogurt directly affect its taste, stability, and consumer acceptance. The textural properties of Guangfo Shou dietary fiber yogurt (FDFY) and additive-free yogurt (0Y) were determined, and the characteristics are shown in Table 2. Compared with 0Y, FDFY showed significantly higher hardness, viscosity, and chewiness by 12.34%, 25.94%, and 17.47%, respectively. P <0.05). Hardness reflects the firmness of the yogurt gel; its increase indicates a denser and stronger yogurt gel network, improving yogurt stability. Adhesion reflects the stickiness and residue of yogurt in the mouth; its increase indicates that the dietary fiber from *Gynostemma pentaphyllum* can enhance the adhesion of yogurt in the mouth and prolong its flavor. Chewiness is determined by both hardness and adhesion, comprehensively reflecting the overall acceptability of yogurt. Its increase may be due to the addition of dietary fiber from *Gynostemma pentaphyllum* forming a high-viscosity solution, thereby enhancing chewiness. This indicates that dietary fiber from *Gynostemma pentaphyllum* can enrich the overall taste of yogurt. Therefore, dietary fiber from *Gynostemma pentaphyllum* can improve the textural properties of yogurt by strengthening its gel structure, enhancing its oral adhesion, and enriching its taste, thereby improving yogurt stability and taste and ultimately improving yogurt quality.

[0088] Table 2 Texture characteristics of Guangfo Shou dietary fiber yogurt and zero-additive yogurt

[0089] Note: * indicates a significant difference between different rows. P <0.05) II. Water-holding capacity of yogurt Water-holding capacity is a core indicator for evaluating yogurt quality, directly reflecting the stability of the yogurt gel structure. Insufficient water-holding capacity leads to whey separation, affecting yogurt quality and consumer acceptance. The water-holding capacity of Guangfo Shou dietary fiber yogurt and zero-additive yogurt under optimal conditions was measured, and the experimental results are as follows: Figure 1 As shown, the water-holding capacity of Guangfo Shou dietary fiber yogurt reached 62.89%±1.43%, significantly higher than that of 0Y ( P <0.05).

[0090] III. Rheological Properties of Yogurt The apparent viscosity of yogurt is a macroscopic manifestation of the density of its internal network. Storage modulus G' and loss energy G'' reflect the elastic strength of the gel network and are key indicators for evaluating yogurt's firmness and structural stability. The rheological properties of yogurt are as follows: Figure 2 As shown, the apparent viscosity of both types of yogurt decreased with increasing shear rate, exhibiting shear-thinning behavior. At all shear rates, the apparent viscosity of FDFY was greater than 0Y. This indicates that the dietary fiber from *Gynostemma pentaphyllum* can enhance the gel network structure of yogurt and improve product stability.

[0091] Furthermore, at low shear rates, the apparent viscosity of both yogurts showed a trend of first increasing and then decreasing. This may be because the gel network of the yogurt was relatively intact in the initial stage, exhibiting strong resistance to flow, and the viscosity decreased as the gel network was disrupted. At all frequencies, the storage modulus of both yogurts was higher than the loss modulus, indicating an elastic-dominated yogurt gel system. Simultaneously, G' and G'' of FDFY were higher than 0Y throughout the entire process. This suggests that the interaction between the dietary fiber of *Gynostemma pentaphyllum* and yogurt protein enhanced the gel network structure of the yogurt. These results indicate that the addition of dietary fiber from *Gynostemma pentaphyllum* can improve the rheological properties of yogurt by enhancing its gel network structure.

[0092] IV. Yogurt particle size Particle size analysis of yogurt reflects the size and distribution of fat globules and protein particles, affecting the yogurt's texture, stability, and digestibility. Studies show that smaller particle sizes result in more uniform and stable texture in yogurt, while excessively large particle sizes can lead to whey separation, affecting its shelf life. Particle size analysis of FDFY and OY yielded the following results: Figure 3 As shown, the particle size distribution of both types of yogurt exhibits a bimodal pattern. The particle size distribution of 0Y is between 300 nm and 8000 nm, with an average particle size of 3467 nm. The particle size distribution of FDFY is between 100 nm and 3000 nm, with an average particle size of 1056.2 nm, which is significantly lower than that of 0Y. This indicates that the addition of *Gynostemma pentaphyllum* dietary fiber reduces the particle size of the yogurt and makes its distribution more uniform.

[0093] V. Fourier Transform Infrared Spectroscopy The results of infrared spectroscopy of yogurt are as follows Figure 4 As shown, compared to 0Y, FDFY is at 1342 cm. -1 and 1107 cm -1 The absorption peak at this point is enhanced. This is usually attributed to the CH bending vibration and CO stretching vibration, which are the main characteristic peaks of polysaccharides. It is speculated that the addition of dietary fiber from *Gynostemma pentaphyllum* may indirectly affect the vibrational intensity in this region by changing the protein conformation or hydrogen bond network.

[0094] Infrared spectroscopy results of yogurt casein showed that, compared to 0Y, FDFY had a higher concentration at 3382 cm⁻¹. -1 A broad and strong absorption peak appeared nearby, at 3382 cm⁻¹. -1 The absorption peak is usually attributed to the stretching vibration of the hydroxyl group (-OH). The appearance of this peak indicates that the sample contains hydroxyl groups or OH bonds related to water molecules and hydrogen bonds, suggesting that the dietary fiber of *Gynostemma pentaphyllum* introduces more hydrophilic groups; FDFY at 1560 cm⁻¹ -1 The absorption peak weakens and redshifts slightly at 1560 cm⁻¹ -1 The absorption peak is usually attributed to the superposition of the in-plane bending vibration of NH and the stretching vibration of CN. These two vibrational modes are very sensitive to the hydrogen bonding environment. This change indicates that the hydrogen bond network of the protein has been rearranged. It may be due to the fact that the dietary fiber of Guangfo Shou (a type of yogurt) causes a redistribution of hydrogen bonds in the main chain and side chain of yogurt protein by competing with the protein for water molecules or by interacting directly with the protein, thereby changing the network structure of yogurt protein; FDFY at 1413 cm⁻¹ -1 1049 cm -1 And 921 cm -1 The absorption peaks at these points are enhanced, and these wavenumbers correspond to CH2 bending and C, respectively. O stretch and C The out-of-plane vibration of H is the main characteristic peak of polysaccharides. This phenomenon directly indicates that the dietary fiber of *Gynostemma pentaphyllum* forms a polysaccharide structure in the yogurt matrix and interacts with other components.

[0095] Infrared data of yogurt at 1700 cm -1 -1600 cm -1 Second-order wavelength fitting yielded the secondary structure distribution of yogurt proteins, as shown in Table 3. Significant differences exist in the secondary structure distribution of proteins between the two yogurts. Compared to 0Y, FDFY shows a greater difference in the secondary structure distribution at the whole protein level. β - The content of folded structures increased by 166.7%, and the content of random curls and β - Reduced content of turn structures; at the casein level β - The folded structure improves efficiency by 120%, and the irregular curling and β - The decreased content of turn-shaped structures indicates that the addition of dietary fiber induced the secondary structure of yogurt proteins to... β - Folded structure arrangement. β - Folding is β - The folded segments form parallel or antiparallel sheet structures through regular main-chain hydrogen bonds, enabling the formation of a denser, more cross-linked protein network during yogurt coagulation. This significantly enhances gel hardness, water retention, and elasticity compared to random curling and... β - The corners offer higher rigidity and better emulsification stability. Guangfo Hand Dietary Fiber Yogurtβ The increased structure may be due to the introduction of more hydroxyl groups by the dietary fiber of *Gynostemma pentaphyllum*, leading to an increase in hydrogen bonds and thus promoting protein chain stretching. β - Folding offers greater possibilities. Furthermore, the water-absorbing properties of the dietary fiber in *Gynostemma pentaphyllum* increase the viscosity of the yogurt, which helps... β - Stability of folding.

[0096] Table 3. Protein secondary structure distribution of Guangfo Shou dietary fiber yogurt and additive-free yogurt

[0097] Example 3: Evaluation of the weight loss and lipid-lowering activity of yogurt containing dietary fiber from the Buddha's Hand citron. I. Determination of in vitro pancreatic lipase inhibitory activity 1. In vitro pancreatic lipase inhibitory activity assay method Take 20 g of yogurt sample and centrifuge at 10000 r / min for 10 min at 4℃. After centrifugation, quickly collect the supernatant and filter it through a 0.45 μm filter membrane to obtain yogurt extract. Mix 80 μL of 50 mmol / L Tris-HCl buffer (pH 8.0), 40 μL of yogurt extract, and 120 μL of 10 mg / mL pancreatic lipase solution thoroughly and incubate at 37℃ for 10 min. Immediately add 160 μL of 0.8 mmol / L p-nitrobenzene palmitate (pNPP) as substrate and react at 37℃ for 20 min. After the reaction, terminate the reaction at 100℃ for 5 min. Take 200 μL of the mixture and measure the absorbance A1 at 405 nm. Use an equal volume of distilled water instead of yogurt extract to measure absorbance A0, and use an equal volume of buffer solution instead of pancreatic lipase solution to measure absorbance A2. The pancreatic lipase inhibitory activity is calculated using the following formula: Pancreatic lipase inhibition rate (%) = ( )*100 2. Test results of different yogurts Resistant dextrin yogurt (RDFY): The difference between this and Guangfoshou dietary fiber yogurt is that Guangfoshou dietary fiber is replaced with resistant dextrin during the preparation process.

[0098] Pumpkin Seed Dietary Fiber Yogurt (PDFY): The difference between PDFY and Guangfo Shou Dietary Fiber Yogurt is that Guangfo Shou dietary fiber is replaced with pumpkin seed dietary fiber during the preparation process.

[0099] Fermented Mixed Dietary Fiber Yogurt (0+FDFY): After the zero-additive yogurt has finished fermenting, Guangfo Shou dietary fiber is added to make its concentration the same as that of Guangfo Shou dietary fiber in FDFY yogurt.

[0100] Yogurt was prepared using resistant dextrin and pumpkin seed dietary fiber to compare the effects of dietary fiber from different sources on the inhibitory activity of pancreatic lipase in yogurt. Results are as follows: Figure 5 As shown, compared with resistant dextrin yogurt (RDFY), Guangfo Shou dietary fiber yogurt (FDFY) showed a significant increase of 102.78% in pancreatic lipase inhibitory activity. P <0.05); significantly higher than pumpkin seed dietary fiber yogurt (PDFY) by 30.64% ( P The value <0.05 indicates that the yogurt prepared from the dietary fiber of *Gynostemma pentaphyllum* has superior pancreatic lipase inhibitory activity compared to dietary fiber from other sources.

[0101] The pancreatic lipase inhibitory activities of yogurt without added *Gynostemma pentaphyllum* dietary fiber (0Y), yogurt with added *Gynostemma pentaphyllum* dietary fiber (FDFY), commercially available yogurt (CY), fermented mixed dietary fiber yogurt (0+FDFY), and yogurt with added *Gynostemma pentaphyllum* dietary fiber at the same concentration (FDF) were compared. The experimental results are as follows: Figure 6 As shown in the figure, among the four types of yogurt, the pancreatic lipase inhibitory activity of the yogurt containing Guangfo Shou dietary fiber was 74.14%, which was 25.03% higher than that of yogurt mixed with the same concentration of Guangfo Shou dietary fiber after fermentation. P <0.05%, compared with the same concentration of Guangfo Shou dietary fiber, its pancreatic fat inhibition rate increased by 31.54% ( P The value <0.05 indicates that co-fermentation of Guangfo Shou dietary fiber and yogurt can significantly enhance the pancreatic lipase inhibitory activity of yogurt.

[0102] II. Obese Rat Model Experiment 1. Test Methods Obese rat model: Forty-eight male SD rats were acclimatized for one week and divided into 6 groups of 8 rats each (4 rats / cage), as shown in the table. The normal control group was fed a basal diet, while the other groups were fed a high-fat diet. After 6 weeks, their weight was measured to confirm the establishment of the model. The rats were administered medication by gavage three times daily, with free access to food and water, as shown in Table 4, for 6 weeks. During the experiment, the rats' growth was observed daily, their diet was changed and food intake was recorded, and their weight was measured weekly. The dosage was adjusted accordingly based on their weight. After the last administration, the rats were fasted for 12 hours but allowed free access to water. They were then weighed, injected intraperitoneally with anesthesia, and blood was collected from the abdominal aorta for dissection.

[0103] Preparation methods of the low-dose, medium-dose, and high-dose groups of Guangfoshou dietary fiber yogurt: The difference from the Guangfoshou dietary fiber yogurt in Example 1 is that the amount of Guangfoshou dietary fiber added is as shown in Table 4. The preparation method of the yogurt in the 0-Y group is the same as that of the zero-added yogurt (0Y) in Example 2, which is yogurt without added Guangfoshou dietary fiber, i.e., blank yogurt.

[0104] Table 4 Animal grouping and treatment

[0105] Food utilization rate determination: During the experiment, the total calories consumed by rats and the weight gain of rats were recorded, and the food utilization rate was calculated according to the following formula.

[0106]

[0107] Body fat percentage: Rats were weighed before sacrifice after fasting for 12 hours. After sacrifice, the subcutaneous fat, perirenal fat and epididymal fat were weighed separately, and the total weight was recorded as the weight of adipose tissue. Body fat percentage was calculated using the following formula.

[0108] 2. Effects of different treatment groups on the body weight of obese rat model Throughout the experiment, the rats' body weight changed as follows: Figure 7 As shown. At the end of week six, the difference in body weight between the model group and the normal control group was significant ( P <0.05, indicating that the obesity model was established. At the end of the experiment, compared with the normal group, the final body weight and weight gain of the rats in the model group were significantly higher ( P <0.05%, respectively, increasing by 46.24% and 80.07%; compared with the model group, the low, medium, and high doses of Guangfoshou dietary fiber yogurt groups showed a significant decrease in final body weight of 4.85%, 7.23%, and 10.94%, respectively. P <0.05%, and weight gain decreased significantly by 5.70%, 9.82%, and 15.91% (%). P <0.05); Compared with yogurt without added citronella dietary fiber, the low, medium, and high dose citronella dietary fiber yogurt groups showed significant final weight reductions of 6.14%, 8.49%, and 12.16%, respectively. P <0.05), and weight gain decreased significantly by 7.66%, 11.70%, and 17.67%, respectively. P <0.05%. This indicates that the weight gain of rats was significantly slowed after intervention with Guangfo Shou dietary fiber yogurt. P <0.05, which has a significant inhibitory effect on obesity induced by a high-calorie diet ( P <0.05).

[0109] 3. Effects of different treatment groups on food intake and food utilization in obese rats Changes in food intake of rats during the experiment are as follows: Figure 8 As shown, food utilization rate is as follows Figure 9As shown, the food intake of rats in each group fluctuated within a certain range. This fluctuation is a normal phenomenon caused by various environmental and physiological factors. The food intake of the NC group was significantly higher than that of the other groups, but the calorie intake was significantly lower than that of the other groups. This was mainly due to the difference in energy density between the normal diet and the high-fat diet. There was no significant difference in food intake among the other experimental groups during the experiment. P >0.05 indicates that the weight change is mainly due to improved lipid metabolism rather than reduced energy intake.

[0110] 4. Effects of different treatment groups on body fat content and body fat percentage in obese rats The body fat content and body fat percentage of rats are as follows Figure 10 As shown, the epididymal fat and perirenal fat of the model group rats were 26.84 g and 23.52 g, respectively. Compared with the normal group, the fat content and body fat percentage of the model group rats were significantly increased. P <0.05), epididymal fat and perirenal fat increased by 222.09% and 134.20%, respectively, and body fat percentage increased by 79.70%; compared with the model group, epididymal fat in rats in the medium and high dose Guangfoshou dietary fiber yogurt groups decreased by 16.21% and 21.72%, respectively ( P <0.05); perirenal fat decreased by 14.29% and 28.74% ( P <0.05); body fat percentage decreased by 9.44% and 14.65% ( P <0.05); Compared with yogurt without added Guangfoshou dietary fiber, the epididymal fat in rats in the medium- and high-dose Guangfoshou dietary fiber yogurt groups decreased by 20.68% and 25.88%, respectively ( P <0.05); perirenal fat decreased by 13.61% and 28.20% ( P <0.05); body fat percentage decreased by 11.46% and 16.55% ( P The value of <0.05 indicates that Guangfo Shou dietary fiber yogurt can effectively reduce body fat accumulation and improve obesity.

[0111] III. Effects of Guangfo Shou Dietary Fiber Yogurt on Blood Lipid Levels in Rats with Mixed Hyperlipidemia 1. Test Methods Mixed hyperlipidemia model: Forty-eight male SD rats were acclimatized for one week and divided into 6 groups of 8 rats each (4 rats / cage), as shown in the table. The normal control group was fed a basal diet, while the other groups were fed a high-cholesterol diet. After 2 weeks, serum lipid levels were measured to confirm the model's establishment. Rats were administered medication by gavage three times daily, with free access to food and water, as per Table 4, for 30 days. During the experiment, the rats' growth was observed daily, their diet was changed and food intake recorded, and their weight was measured weekly. Dosage was adjusted based on weight. After the last administration, rats were fasted for 12 hours but allowed free access to water. They were then weighed, injected intraperitoneally with anesthesia, and blood was collected from the abdominal aorta for dissection.

[0112] Blood lipid levels: After intraperitoneal injection of anesthesia into rats, blood was collected from the abdominal aorta using a blood collection needle into a blood collection tube. The tubes were allowed to stand and separate into layers, then centrifuged at 8000 r / min for 10 min. The serum was collected and stored at -80℃. The levels of TC, TG, LDL-C, and HDL-C in the serum were measured according to the kit instructions.

[0113] 2. Test Results A high-fat diet leads to abnormal lipid metabolism in rats. Serum levels of triglycerides (TG), total cholesterol (TC), LDL-C, and HDL-C are important indicators for assessing blood lipid levels. TG is the body's main form of energy storage; excessive energy intake stimulates the liver to synthesize large amounts of triglycerides. The blood lipid levels in rats are as follows: Figure 11 As shown, the TG content in the normal group (NC) rats was 0.69 mmol / L, while the TG content in the model group (HL) rats was 1.82 mmol / L, which was significantly higher than that in the normal group by 165.40%. P <0.05, the TG content in rats in the medium and high doses of Guangfo Shou dietary fiber yogurt groups was 0.95 mmol / L and 0.8 mmol / L, respectively, which were significantly reduced by 47.82% and 56.11% compared with the model group. P <0.05); compared with yogurt without added Buddha's hand dietary fiber, it significantly reduced by 35.24% and 45.53% ( P <0.05). This indicates that the Guangfo Shou dietary fiber yogurt (FDFY) can effectively reduce triglycerides in rat serum, thereby alleviating abnormal lipid metabolism.

[0114] TC is an essential sterol compound that participates in various physiological reactions and plays an important physiological role. However, excessively high TC levels can easily induce cardiovascular diseases. Figure 11 As shown, the TC content in the normal group rats was 2.64 mmol / L, while the TC content in the model group (HL) rats was 8.33 mmol / L, an increase of 147.17%. P<0.05, the TC content in rats in the medium and high dose Guangfoshou dietary fiber yogurt intervention groups was 6.74 mmol / L and 5.50 mmol / L, respectively, which were significantly reduced by 19.00% and 34% compared with the model group. P <0.05); compared with yogurt without added Guangfo Shou dietary fiber, the levels were reduced by 18.59% and 33.63% respectively ( P <0.05%. This indicates that the Guangfo Shou dietary fiber yogurt (FDFY) can effectively reduce the cholesterol level in rat serum.

[0115] LDL-C is a lipoprotein particle that carries cholesterol into peripheral tissue cells. High concentrations of LDL-C can easily lead to cholesterol accumulation on the arterial walls, thereby causing atherosclerosis. Figure 11 As shown, the LDL-C content in the normal group rats was 0.94 mmol / L, while the LDL-C content in the model group (HL) rats was 7.05 mmol / L, an increase of 518.12%. P <0.05); The LDL-C levels in rats in the medium- and high-dose Guangfo Shou dietary fiber yogurt intervention groups were 5.60 mmol / L and 4.24 mmol / L, respectively, which were significantly reduced by 20.54% and 39.90% compared with the model group. P <0.05%, which is 20.35% and 39.76% lower than that of yogurt without added Guangfo Shou dietary fiber. P <0.05%. This indicates that the Guangfo Shou dietary fiber yogurt (FDFY) can effectively reduce the level of low-density lipoprotein in rats.

[0116] HDL-C is rich in phospholipids, which can transport excess cholesterol from foam macrophages, smooth muscle cells, and peripheral tissues to the liver, promoting the conversion of cholesterol into bile acids or its excretion in bile, thus helping to lower blood lipid levels. Figure 11 As shown, the HDL-C content in the normal group rats was 0.87 mmol / L, while the HDL-C content in the model group (HL) rats was 0.49 mmol / L, a decrease of 43.95%. P <0.05, the HDL-C levels in rats in the medium- and high-dose Guangfo Shou dietary fiber yogurt intervention groups were 0.79 mmol / L and 0.817 mmol / L, respectively, which were significantly increased by 62.13% and 65.53% compared with the model group. P <0.05); compared to yogurt without added Guangfo Shou dietary fiber, it increased by 42.13% and 45.11% ( P <0.05). This indicates that the dietary fiber yogurt from Guangfo Shou can effectively increase the level of high-density lipoprotein in rat serum, thereby alleviating dyslipidemia.

[0117] Example 4: Optimization of the process for making Guangfo Shou dietary fiber yogurt I. Single-factor experiment Five influencing factors were selected: the amount of dietary fiber added from *Guangfo Shou* (a type of yogurt), the amount of sucrose added, the fermentation time, the amount of starter culture, and the fermentation time. The effects of each factor on yogurt quality were investigated using a single-factor experiment. After normalizing the weighting of texture (hardness, viscosity, and chewiness), acidity, and sensory properties, they were assigned weights of 10%, 10%, 10%, and 60%, respectively. The specific settings are as follows: The effects of different amounts of dietary fiber from *Gynostemma pentaphyllum* (1.3%, 1.5%, 1.7%, 1.9%, 2.1%) on yogurt quality were investigated using the following methods: 11% sucrose, 0.05‰ starter culture, 4 h fermentation time, and 42 ℃ fermentation temperature. Suitable factor levels were determined. Similarly, the effects of different amounts of dietary fiber from *Gynostemma pentaphyllum* (1.7%), 0.05‰ starter culture, 4 h fermentation time, and 42 ℃ fermentation temperature were investigated using the following methods: 5%, 7%, 9%, 11%, 13% sucrose, 1.7% sucrose, 11% sucrose, 0.05‰ starter culture, 42 ℃ fermentation temperature. Suitable factor levels were determined. Finally, the effects of different amounts of dietary fiber from *Gynostemma pentaphyllum* (1.7%), sucrose, 0.05‰ starter culture, and 0.07‰ starter culture were investigated using the following methods: 1.7% sucrose, 11% sucrose, 0.05‰ starter culture, and 42 ℃ fermentation temperature. The effects of fermentation time (2 h, 3 h, 4 h, 5 h, 6 h) on yogurt quality were investigated to determine the appropriate factor levels. The effects of fermentation temperature (40℃, 41℃, 42℃, 43℃, 44℃) on yogurt quality were investigated with 1.7% added shiitake mushroom dietary fiber, 11% added sucrose, 0.05‰ inoculum, and 4 h fermentation time to determine the appropriate factor levels.

[0118] II. Results of Single-Factor Experiments 1. The effect of added dietary fiber from *Gynostemma pentaphyllum* on yogurt quality The effect of added dietary fiber from *Gynostemma pentaphyllum* on yogurt quality is shown in Table 5. The overall score of the yogurt first increased and then decreased with the increase of added dietary fiber from *Gynostemma pentaphyllum*. When the added dietary fiber from *Gynostemma pentaphyllum* was 1.7%, the yogurt had a rich and fragrant aroma, uniform texture, and bright color. Its hardness, viscosity, chewiness, acidity, and sensory scores were 77.73g±1.97 g, -117.31 g•s±4.88 g•s, 49.03 g±3.04 g, 83.79°T±0.51°T, and 79.00±3.87, respectively. Its overall score reached 0.67±0.5, which was significantly higher than other groups. P<0.05); When the dietary fiber content of *Gynostemma pentaphyllum* exceeded 1.7%, the yogurt developed an unpleasant bitter taste, and the overall score decreased significantly. P <0.05). This may be due to substances such as limonene and naringin contained in the dietary fiber of Guangfo Shou (a type of citronella). Therefore, the amount of Guangfo Shou dietary fiber added (1.5%, 1.7%, and 1.9%) was selected as the optimization parameter to carry out a response surface optimization experiment on Guangfo Shou dietary fiber yogurt.

[0119] Table 5. Effects of added dietary fiber from Guangfo Hand on yogurt quality

[0120] 2. The effect of added sucrose on yogurt quality The effect of sucrose addition on yogurt quality is shown in Table 6. The overall score of yogurt first increased and then decreased with the increase of sucrose addition. When the sucrose addition was less than 11%, the yogurt tasted too sour and not sweet enough; when the sucrose addition was 11%, the yogurt had a suitable sweet and sour taste and good palatability. Its hardness, viscosity, chewiness, acidity, and sensory scores were 79.72 g±0.62 g, -138.06 g•s±3.63 g•s, 53.49 g±1.73 g, 83.75 °T±1.27 °T, and 76.50±2.94, respectively, and its overall score reached 0.73±0.08, which was significantly higher than other groups. P <0.05); When the added sucrose is greater than 11%, the sweet-sour ratio of the yogurt is unbalanced and the texture is too thick, resulting in a significant decrease in the overall score. P <0.05). Therefore, the sucrose addition amount (9%, 11%, 13%) was selected as the optimization parameter to carry out the response surface optimization experiment of Guangfo Hand dietary fiber yogurt.

[0121] Table 6. Effects of sucrose addition on yogurt quality

[0122] Note: Different letters indicate significant differences between different rows. P <0.05) 3. The effect of starter culture inoculation amount on yogurt quality The effect of starter culture inoculum amount on yogurt quality is shown in Table 7. The overall score of yogurt first increased and then stabilized with the increase of starter culture inoculum amount. When the starter culture inoculum amount was 0.05‰, the yogurt had a uniform and delicate texture and a suitable taste. Its hardness, viscosity, chewiness, acidity, and sensory scores were 73.39 g±1.88 g, -109.96 g•s±2.17 g•s, 45.83 g±0.19 g, 81.37 °T±0.80 °T, and 81.20±0.87, respectively, and its overall score reached 0.66±0.07. Further increasing the inoculum amount did not significantly change the overall score of yogurt (P>0.05). Therefore, a starter culture inoculum amount of 0.05‰ was selected as a fixed parameter to conduct a response surface methodology optimization experiment on the dietary fiber of *Gynostemma pentaphyllum*.

[0123] Table 7. Effect of starter culture inoculum amount on yogurt quality

[0124] Note: Different letters indicate significant differences between different rows. P <0.05) 4. The effect of fermentation time on yogurt quality The effect of fermentation time on yogurt quality is shown in Table 8. The overall score of yogurt first increased and then decreased with the extension of fermentation time. Both too short and too long fermentation times affect the formation of yogurt texture, resulting in poor yogurt quality. When the fermentation time is less than 4 hours, the acidity of the yogurt is insufficient, and incomplete fermentation leads to a strong milky taste and thin texture. When the fermentation time is 4 hours, the acidity of the yogurt is suitable, and the texture is delicate and uniform. Its hardness, viscosity, chewiness, acidity, and sensory scores are 73.39 g±1.88 g, -106.62 g•s±2.63 g•s, 44.03 g±1.60 g, 84.08°T±0.72°T, and 76.40±3.01, respectively. Its overall score reaches 0.74±0.06, which is significantly higher than other groups. P <0.05); When the fermentation time was greater than 4 hours, the yogurt was over-fermented, exhibiting a strong sour taste and whey separation, resulting in a significant decrease in the overall score. P <0.05). Therefore, fermentation time (3 h, 4 h and 5 h) was selected as the optimization parameter to carry out response surface optimization experiments on Guangfo Hand dietary fiber yogurt.

[0125] Table 8. Effect of fermentation time on yogurt quality

[0126] Note: Different letters indicate significant differences between different rows. P <0.05) 5. The effect of fermentation temperature on yogurt quality The effect of fermentation temperature on yogurt quality is shown in Table 9. The overall score of the yogurt first increased and then stabilized with increasing fermentation temperature. When the fermentation temperature was 42 ℃, the yogurt had a uniform texture, bright color, and good palatability. Its hardness, viscosity, chewiness, acidity, and sensory scores were 75.75 g ± 0.67 g, -107.90 g·s ± 1.61 g·s, 45.03 g ± 1.60 g, and 82.33 g, respectively. ° T±0.47 ° T and 80.90±0.70, with a comprehensive score of 0.75±0.07. However, as the fermentation temperature continued to increase, the comprehensive score of the yogurt did not change significantly. P Since the value is greater than 0.05, a fermentation temperature of 42℃ was chosen as a fixed parameter to conduct a response surface optimization experiment on Guangfo Hand dietary fiber yogurt.

[0127] Table 9. Effect of fermentation temperature on yogurt quality

[0128] Note: Different letters indicate significant differences between different rows. P <0.05) Example 5: Response Surface Design and Yogurt Quality Characteristics I. Response Surface Methodology Based on the single-factor experimental results of Example 3, with a fixed inoculum size of 0.05‰ and a fermentation temperature of 42℃, the following factors were selected: the amount of dietary fiber added from *Gynostemma pentaphyllum* (A), the amount of sucrose added (B), and the fermentation time (C). A three-factor, three-level response surface methodology was designed using the Box-Behnken principle to determine the optimal process parameters for producing *Gynostemma pentaphyllum* dietary fiber yogurt. The experimental factors and levels are shown in Table 10.

[0129] Table 10 Factors and Levels in Response Surface Analysis

[0130] II. Response Surface Experiment Results Based on the results of the single-factor experiments, three factors were selected: the amount of dietary fiber added to the Buddha's Hand fruit, the amount of sucrose added, and the fermentation time. The response surface optimization experimental design was carried out with the comprehensive score (Y) after weighting hardness, adhesiveness, chewiness, acidity, and sensory properties as the response value. The results are shown in Table 11.

[0131] Table 11 Box-Benhnken Experimental Design and Results

[0132] The data were subjected to multiple regression fitting analysis using Design-Expert software. The regression equations for the comprehensive score Y and the amount of dietary fiber, sucrose, and fermentation time of the *Gynostemma pentaphyllum* were obtained as follows:

[0133] The results of the response surface methodology analysis are shown in Table 12. The F-value of this model is 90.37. P The value <0.0001 indicates that the model factors are statistically significant. The model's lack-fit term F is 4.92. P >0.05, no significant difference. The reliability analysis of the quadratic regression equation is shown in Table 13, with a correlation coefficient R0.05. 2 =0.9915, Corrected coefficient of determination Radj 2 =0.9805. The signal-to-noise ratio (SNR) is an indicator that measures the strength of the model's predicted signal relative to the experimental error, reflecting the model's ability to identify experimental errors. A ratio greater than 4 is generally considered ideal. The coefficient of variation (CV%) is an indicator that measures the relative dispersion of experimental data or model residuals, reflecting the accuracy of the experiment or the reliability of the model. As shown in the table, the model's SNR is 26.7318, and the CV% is 4.45%, indicating a good fit and high feasibility and reliability. This model can be used to analyze and predict the quality of Guangfo Shou dietary fiber yogurt. The analysis results show that the influence of each factor on the overall score of Guangfo Shou dietary fiber yogurt in this model is in the following order: fermentation time (C) > dietary fiber addition (A) > sucrose addition (B).

[0134] Table 12 Analysis of Variance of Regression Equations

[0135] Note: P <0.05 indicates that the model or the factors under investigation have a significant impact; P A value <0.01 indicates that the influence of the model or the factors under investigation is extremely significant.

[0136] Table 13 Reliability Analysis of the Quadratic Regression Equation

[0137] II. Response Surface Analysis of Multi-Factor Interactions The three-dimensional response surface and contour lines of the effects of the interaction of various factors on the quality of Guangfo Shou dietary fiber yogurt are shown in Figure 1. Figure 12 As shown, the amount of dietary fiber and sucrose added to Guangfo Shou (a type of citrus fruit) is... Figure 12 The three-dimensional response surface plots (Figures A and B) are relatively flat, and the contour plots are approximately circular, indicating that the interaction is not significant; the amount of dietary fiber added and the fermentation time of *Gynostemma pentaphyllum* (a type of citrus fruit) are relatively stable. Figure 12The surface of the three-dimensional response plot (Figures C and D) is relatively flat, and the contour plot is slightly close to an ellipse, indicating that the interaction is not significant; the amount of sucrose added and the fermentation time (Figures C and D) Figure 12 The three-dimensional response surface plots (E and F plots) show steep surfaces and contour lines that are close to ellipses, indicating significant interactions.

[0138] Response surface methodology analysis revealed the optimal process for producing Guangfo Hand dietary fiber yogurt as follows: 1.75% Guangfo Hand dietary fiber, 11.27% sucrose, and 4.09 h fermentation time. Under these conditions, the overall score reached 0.779. Considering practical operation, the parameters were adjusted to 1.75% Guangfo Hand dietary fiber, 11% sucrose, and 4 h fermentation time. The resulting yogurt achieved an overall score of 0.78, which is close to the predicted value.

[0139] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. Application of dietary fiber from *Gnaphalium affine* in the preparation of weight-loss and lipid-lowering yogurt.

2. Application of Guangfo Shou dietary fiber in the preparation of yogurt that helps control body fat, or in the preparation of yogurt that helps maintain healthy blood lipid levels.

3. A method for preparing a yogurt made with the dietary fiber of *Gynostemma pentaphyllum*, characterized in that, Add Guangfo Shou dietary fiber to the yogurt fermentation ingredients.

4. The preparation method according to claim 3, characterized in that, The amount of dietary fiber added to the *Gynostemma pentaphyllum* is 13-21 mg / mL.

5. The preparation method according to claim 3, characterized in that, Yogurt starter contains Streptococcus thermophilus (Streptococcus thermophilus) Streptococcus thermophiles Lactobacillus bulgaricus ( Lactobacillus bulgaricus Bifidobacterium bifidum ( Bifidobacterium bifidum Bifidobacterium animalis ( Bifidobacterium animalis Bifidobacterium longum ( Bifidobacterium longum ), Lactobacillus acidophilus ( Lactobacillus acidophilus Lactobacillus casei ( Lactobacillus casei One or more of the following.

6. The preparation method according to claim 5, characterized in that, The amount of the fermentation agent added is 0.04~0.07 g / L.

7. The preparation method according to claim 3, characterized in that, The raw materials for yogurt fermentation include: 13-21 mg / mL of Guangfo Shou dietary fiber, 0.04-0.07 g / L of starter culture, 90-150 mg / mL of sweetener, and the remainder being raw milk; the raw milk is one or more of raw milk, pure milk, and reconstituted milk.

8. The preparation method according to claim 3, characterized in that, The fermentation conditions for yogurt are 41-44℃ for 3-6 hours.

9. The yogurt made from the dietary fiber of *Gynostemma pentaphyllum* prepared by any one of claims 3 to 8.

10. The use of the Guangfo Shou dietary fiber yogurt according to claim 9 in the preparation of weight loss and / or lipid-lowering products.

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