A method for producing a hawthorn fruit jujube peel fermented by probiotics

Abstract

This invention discloses a method for producing probiotic-fermented hawthorn fruit leather. Using hawthorn as raw material, the method involves probiotic fermentation, which not only preserves the nutritional and functional components of hawthorn but also endows the probiotics with health benefits, combining the flavor of the raw material with the flavor of fermentation. Simultaneously, the probiotics utilize the sugars and organic acids in hawthorn as a carbon source to promote their growth and proliferation, reducing the reducing sugar content in the fruit pulp. The resulting fermentation products, such as extracellular polysaccharides and short-chain fatty acids, contribute to human health. The probiotic-fermented hawthorn fruit leather prepared by this invention meets the demands of the modern health industry and is conducive to the sustainable development of modern industry. This product is produced in cooperation with Chengde Yida Food Co., Ltd., facilitating industrial-scale production.

Description

Technical Field

[0001] This invention relates to a method for producing probiotic-fermented hawthorn fruit leather. Background Technology

[0002] Hawthorn (Crataegus pinnatifida Bunge), a plant belonging to the genus Crataegus in the Rosaceae family, is rich in nutrients and contains bioactive compounds such as polyphenols, phenylalanine, and flavonoids, which have antioxidant, anti-inflammatory, and lipid-lowering effects. Hawthorn fruit leather is a candied fruit product made primarily from hawthorn, which is rich in pectin and organic acids. It is produced through processes such as making jam, slicing, drying, and shaping, resulting in a thin, long, rolled, peel-like appearance. Hawthorn preserves, represented by fruit leather, are a key product in hawthorn processing and are very popular with consumers. Because hawthorn contains high levels of organic acids such as malic acid, citric acid, and succinic acid, a large amount of sucrose needs to be added to adjust the flavor of traditional hawthorn fruit leather, giving it a high-sugar characteristic. Diets characterized by high-sugar foods are considered a major cause of the rapid increase in obesity and metabolic diseases such as diabetes in recent years, severely limiting the consumption of high-sugar foods, including fruit leather, and hindering the sustainable development of the industry. In addition, using functional oligosaccharides and sugar alcohols to replace sucrose in the preparation of hawthorn fruit leather can reduce its sugar content, but the nutritional flavor is limited. Furthermore, fermentation with probiotics not only preserves the nutritional and functional components of the raw materials but also imparts health benefits to the probiotics, giving the product both the flavor of the raw materials and the flavor of fermentation.

[0003] The organic acids and special enzyme systems produced during probiotic fermentation, along with lactic acid metabolism, can improve blood lipids and delay aging. The resulting extracellular polysaccharides possess antioxidant, anticancer, immunomodulatory, antibacterial, hypoglycemic, hypotensive, and cholesterol-lowering properties. Therefore, probiotics are widely used in the food fermentation industry. Currently, the main probiotic fermentation strains used in food include lactic acid bacteria, bifidobacteria, yeast, probiotic Bacillus, and Clostridium butyricum. These are used not only in the fermentation of fruit and vegetable juices made from grapes, apples, carrots, tomatoes, lychees, and blueberries, but also in jam fermentation. Researchers have discovered that lactic acid bacteria fermentation can be used to prepare candied fruit products; for example, fermenting green plums with lactic acid bacteria to reduce acidity produces low-acid green plum candied fruit.

[0004] Currently, there are many processed hawthorn products on the market, with probiotic fermentation-related products mainly concentrated in beverages and yogurt. To date, there are no products using probiotic fermentation to prepare candied hawthorn. Summary of the Invention

[0005] The purpose of this invention is to provide a method for producing probiotic fermented hawthorn fruit leather.

[0006] This invention first protects a method for preparing hawthorn fruit leather, which includes the following steps: using hawthorn as raw material, and fermenting it with probiotics to obtain hawthorn fruit leather.

[0007] In the method, the probiotics can be a single bacterium or a compound bacterium.

[0008] The probiotics may be one or more of lactic acid bacteria, bifidobacteria, and yeast.

[0009] The lactic acid bacteria may be one or more of Lactobacillus bulgaricus, Streptococcus thermophilus, Lactobacillus acidophilus, Lactobacillus plantarum, and Lactobacillus casei.

[0010] Any of the probiotics mentioned above can exist in the form of probiotic powder.

[0011] In one embodiment of the present invention, the probiotics are lactic acid bacteria. The lactic acid bacteria include *Lactobacillus bulgaricus*, *Streptococcus thermophilus*, *Lactobacillus acidophilus*, *Lactobacillus plantarum*, and *Lactobacillus casei*. The lactic acid bacteria exist in the form of lactic acid bacteria powder. In the lactic acid bacteria powder, the mass ratio of *Lactobacillus bulgaricus*, *Streptococcus thermophilus*, *Lactobacillus acidophilus*, *Lactobacillus plantarum*, and *Lactobacillus casei* is 1:1:1:1:1. Specifically, the lactic acid bacteria powder is a lactic acid bacteria yogurt starter powder (classic five-strain type) (10 billion live bacteria / g) purchased from Beijing Chuanxiu Technology Co., Ltd.

[0012] In one embodiment of the present invention, the probiotic is *Lactobacillus plantarum*. The *Lactobacillus plantarum* exists in the form of *Lactobacillus plantarum* powder. Specifically, the *Lactobacillus plantarum* powder (10 billion live bacteria / g) purchased from Xi'an Xinshan Biotechnology Co., Ltd., product number xs-0906.

[0013] In one embodiment of the present invention, the probiotics are a compound of lactic acid bacteria and bifidobacteria. The lactic acid bacteria include *Lactobacillus bulgaricus*, *Streptococcus thermophilus*, *Lactobacillus acidophilus*, *Lactobacillus plantarum*, and *Lactobacillus casei*. The lactic acid bacteria exist in the form of lactic acid bacteria powder. In the lactic acid bacteria powder, the mass ratio of *Lactobacillus bulgaricus*, *Streptococcus thermophilus*, *Lactobacillus acidophilus*, *Lactobacillus plantarum*, and *Lactobacillus casei* is 1:1:1:1:1. Specifically, the lactic acid bacteria powder is lactic acid bacteria yogurt starter powder (classic five-strain type) (10 billion live bacteria / g) purchased from Beijing Chuanxiu Technology Co., Ltd. The bifidobacteria exist in the form of bifidobacteria powder. Specifically, the bifidobacteria powder can be Lizhu Chang Le (bifidobacteria live bacteria capsules) (0.5 billion live bacteria / 0.35g) purchased from Guangdong Lizhu Pharmaceutical Group Co., Ltd., product number 307040018. The mass ratio of the lactic acid bacteria powder to the bifidobacteria powder is 1:1.

[0014] In one embodiment of the present invention, the probiotic is yeast. The yeast exists in the form of yeast powder. Specifically, the yeast powder may be high-activity dry yeast powder (20 billion live bacteria / g) purchased from Hubei Angel Yeast Co., Ltd.

[0015] In the method, the raw materials also include sugars and / or sugar alcohols.

[0016] In the method, the raw materials also include water; the mass ratio of hawthorn, water, sugar and / or sugar alcohol, and probiotics is 100:50-70:10-70:1-5.

[0017] In one embodiment of the present invention, the mass ratio of hawthorn, water, sugar and / or sugar alcohol, and probiotics is 100:55:70:2.

[0018] In one embodiment of the present invention, the mass ratio of hawthorn, water, sugar and / or sugar alcohol, and probiotics is 100:55:70:3.

[0019] In one embodiment of the present invention, the mass ratio of hawthorn, water, sugar and / or sugar alcohol, and probiotics is 100:55:70:5.

[0020] In the raw materials, the sugar is sucrose or oligosaccharide.

[0021] In the raw materials, the sugar alcohol is xylitol, mannitol or sorbitol.

[0022] The oligosaccharide is xylooligosaccharide, konjac mannan oligosaccharide, or fructooligosaccharide.

[0023] In one embodiment of the present invention, the raw material includes sugar, wherein the sugar is sucrose.

[0024] In one embodiment of the present invention, the raw materials include sugar and sugar alcohol, wherein the sugar is an oligosaccharide (specifically konjac mannan oligosaccharide) and the sugar alcohol is xylitol. The mass ratio of the sugar to the sugar alcohol is 1:1.

[0025] In one embodiment of the present invention, the raw materials are hawthorn, water, sucrose and lactic acid bacteria, in a mass ratio of 100:55:70:2.

[0026] In one embodiment of the present invention, the raw materials are hawthorn, water, konjac mannan oligosaccharide, xylitol and lactic acid bacteria, in a mass ratio of 100:55:35:35:3.

[0027] In one embodiment of the present invention, the raw materials are hawthorn, water, konjac mannan oligosaccharide, xylitol and Lactobacillus plantarum, in a mass ratio of 100:55:35:35:3.

[0028] In one embodiment of the present invention, the raw materials are hawthorn, water, konjac mannan oligosaccharide, xylitol, lactic acid bacteria and bifidobacteria, in a mass ratio of 100:55:35:35:1.5:1.5.

[0029] In one embodiment of the present invention, the raw materials are hawthorn, water, sucrose, and yeast, in a mass ratio of 100:55:70:5.

[0030] In the method described above, the fermentation is anaerobic fermentation.

[0031] The fermentation temperature is 30℃-45℃, specifically 38℃.

[0032] The fermentation time is 4 to 16 hours, specifically 4 hours.

[0033] In the method, before anaerobic fermentation, all raw materials are steamed (the specific time can be 25 minutes) and then crushed evenly.

[0034] In the method described, after anaerobic fermentation, the fermented material is pulped, seeds are removed, and then filtered through a 20-mesh sieve. After filtration, the material is spread into sheets, dried, and then unpacked to obtain the hawthorn fruit leather. The moisture content of the hawthorn fruit leather is less than 30%.

[0035] This invention also protects hawthorn fruit leather prepared by any of the methods described above.

[0036] This invention also protects products used in the preparation of hawthorn fruit leather, including hawthorn and any of the probiotics described above.

[0037] The hawthorn mentioned above can specifically be iron hawthorn, with a water content of 60%-70%.

[0038] This invention uses hawthorn as raw material and ferments it with probiotics. This process not only preserves the nutritional and functional components of hawthorn but also endows the probiotics with health benefits, combining the flavor of the raw material with the flavor of fermentation. Simultaneously, the probiotics utilize the sugars and organic acids in hawthorn as a carbon source to promote their growth and proliferation, reducing the reducing sugar content in the fruit pulp. The resulting fermentation products, such as extracellular polysaccharides and short-chain fatty acids, contribute to human health. The probiotic-fermented hawthorn fruit leather prepared by this invention meets the demands of the modern health industry and is conducive to the sustainable development of modern industry. This product is produced in cooperation with Chengde Yida Food Co., Ltd., which facilitates industrial-scale production. Attached Figure Description

[0039] Figure 1 The images show the appearance of the hawthorn fruit leather fermented with lactic acid bacteria in Example 1; A: after drying; B: after packaging. Detailed Implementation

[0040] The following examples are provided to better understand the present invention, but do not limit the invention. Unless otherwise specified, the experimental methods in the following examples are conventional methods. Unless otherwise specified, the experimental materials used in the following examples were purchased from conventional biochemical reagent stores. All quantitative experiments in the following examples were performed in triplicate, and the results were averaged.

[0041] In this embodiment of the invention, the fresh hawthorn used to prepare hawthorn fruit leather is iron hawthorn, which was purchased from Xinglong County, Hebei Province, and has a moisture content of 60%-70%.

[0042] The lactic acid bacteria powder in this embodiment of the invention is a lactic acid bacteria yogurt starter powder (classic five-strain type) purchased from Beijing Chuanxiu Technology Co., Ltd., including Lactobacillus bulgaricus, Streptococcus thermophilus, Lactobacillus acidophilus, Lactobacillus plantarum and Lactobacillus casei (mass ratio of 1:1:1:1:1), 10 billion live bacteria / g.

[0043] The Lactobacillus plantarum powder used in this embodiment of the invention was purchased from Xi'an Xinshan Biotechnology Co., Ltd., with product number XS-0906 and a count of 10 billion live bacteria / g.

[0044] The Bifidobacterium powder in this embodiment of the invention is Lizhu Chang Le (Bifidobacterium live bacteria capsules) purchased from Guangdong Lizhu Pharmaceutical Group Co., Ltd., with product number 307040018 and 0.5 billion live bacteria / 0.35g.

[0045] The yeast powder used in this embodiment of the invention is a high-activity dry yeast powder purchased from Hubei Angel Yeast Co., Ltd., with 20 billion live bacteria per gram.

[0046] Example 1: Lactic acid bacteria fermented hawthorn fruit leather

[0047] I. Preparation of Hawthorn Fruit Leather by Lactic Acid Bacteria Fermentation

[0048] 1. Raw material pretreatment: Select 100g of fresh hawthorn as raw material, wash and drain the water.

[0049] 2. Preparation: Dissolve 70g of sucrose in 55g of water, then add the hawthorn fruit processed in step 1.

[0050] 3. Steaming and pulping: After pouring the mixture obtained in step 2 into a container, place the container in a pressure cooker (pressure of 70 kPa, add 300g of water to the pot) and steam for 20 minutes, then pulp evenly.

[0051] 4. Lactic acid bacteria fermentation: Inoculate 2g of lactic acid bacteria powder into the crushed material obtained in step 3, and anaerobic ferment at 38℃ for 4 hours. Then, pulp and remove seeds from the fermented material and filter it with a 20-mesh filter.

[0052] 5. Spreading: Pour the fruit pulp obtained from filtering in step 4 onto the aluminum foil, fix the height between the scraper and the aluminum foil (3-5mm), and drag the aluminum foil to complete the spreading.

[0053] 6. Drying: After completing step 5, place the spread fruit pulp into the oven, set the oven temperature to 60℃ for both the top and bottom heat, and bake for 8 hours until the moisture content of the sample drops below 30%.

[0054] 7. Removing the sheet: Peel the dried fruit leather from the foil and cut it.

[0055] 8. Packaging and Warehousing: Roll up the cut fruit leather and pack it into storage.

[0056] II. Parameter Detection

[0057] 1. Sensory evaluation

[0058] Ten sensory evaluators were invited to conduct sensory evaluation of lactic acid bacteria fermented hawthorn fruit leather. The evaluation criteria were based on the reference: Li Mo, Liu Fang, Wen Xin, et al. Effect of iron-enriched fermented soybean flour on the quality of fruit leather [J]. Food Industry, 2015(11):147-151. The total score was 100 points, with color accounting for 30 points, taste for 30 points, mouthfeel for 20 points, and texture for 20 points. The results are shown in Table 1. Lactic acid bacteria fermented hawthorn fruit leather showed no significant difference in color, texture, mouthfeel, and total score compared with traditional hawthorn fruit leather (sucrose hawthorn fruit leather prepared without lactic acid bacteria fermentation, whose preparation method is the same as step one, the only difference being the absence of probiotics) (P>0.05).

[0059] Table 1. Comparison of sensory evaluation scores between lactic acid bacteria fermented hawthorn fruit leather and traditional hawthorn fruit leather.

[0060]

[0061] Note: In the same column, data marked with different letters indicate significant differences (P < 0.05). The significance analysis of the data between groups was performed using Duncan(D) multiple comparisons in one-way ANOVA.

[0062] 2. Appearance

[0063] By observing the appearance of the fruit leather, one can determine its color and transparency.

[0064] The appearance of the lactic acid bacteria fermented hawthorn fruit leather prepared according to the process in Example 1 is as follows: Figure 1 As shown. Figure 1 A represents the product after drying. Figure 1 B represents the packaged product. Results showed that the lactic acid bacteria-fermented hawthorn fruit leather had a bright red color and high transparency, closely resembling the color and transparency of traditional hawthorn fruit leather.

[0065] 3. Texture

[0066] Texture parameters of hawthorn fruit leather fermented with lactic acid bacteria were collected using a texture analyzer (method reference: Sun Haitao, Shao Xinru, Jiang Ruiping, et al. Response surface methodology optimization of ultrasonic sugar infiltration process for preparing wild jujube kiwi fruit preserves and its texture analysis [J]. Food Science, 2015, 36(20):49-55.). The results are shown in Table 2. Among the texture characteristics, hardness is a very important indicator for measuring the quality of fruit leather. As can be seen from Table 2, lactic acid bacteria fermentation has a significant effect on the hardness of hawthorn fruit leather, and fermentation reduces the hardness value of hawthorn fruit leather. It can be seen from the table that lactic acid bacteria fermentation has no significant effect on the cohesiveness and elasticity of hawthorn fruit leather (P>0.05). Adhesion is the negative peak area formed by the force and time of the probe, reflecting the adhesiveness of fruit leather. Extracellular polysaccharides are polymers with high molecular weight, produced by probiotic metabolism. When dissolved in water, they form a colloid, which can increase the viscosity of fermented products. Therefore, compared to traditional hawthorn fruit leather, the viscosity of hawthorn fruit leather prepared after lactic acid bacteria fermentation was significantly increased (P<0.05). Chewability is generally a combination of the hardness, cohesiveness, and elasticity of solid foods, and its magnitude represents the energy required to chew the solid food into a swallowable state. As shown in Table 2, the chewability of hawthorn fruit leather prepared by lactic acid bacteria fermentation was not significantly different from that of traditional hawthorn fruit leather (P>0.05). In conclusion, the textural properties of lactic acid bacteria fermented hawthorn fruit leather are similar to those of traditional hawthorn fruit leather.

[0067] Table 2. Structure of Hawthorn Fruit Juice Fermented with Lactic Acid Bacteria

[0068]

[0069]

[0070] Note: Data are expressed as mean ± standard deviation (n=3); in the same column, identical letters indicate no significant difference (P>0.05), while different letters indicate significant difference (P<0.05).

[0071] 4. Color difference

[0072] Color difference data of hawthorn fruit leather fermented with lactic acid bacteria were collected using a colorimeter [Method reference: Li Wenhao, Shen Qun, Jia Yukun, et al. Effects of temperature and light on the color of fruit leather [J]. Journal of Agricultural Product Processing, 2009(5):22-23.], and the results are shown in Table 3. Regarding the L value, there was no significant difference between the hawthorn fruit leather prepared by lactic acid bacteria fermentation and the traditional hawthorn fruit leather (P>0.05). Regarding the a and b values, the size of both values ​​changed in the lactic acid bacteria fermented hawthorn fruit leather compared to the traditional hawthorn fruit leather. ΔE characterizes the color difference and is fitted by L / a / b. Compared to the traditional hawthorn fruit leather, the ΔE of the hawthorn fruit leather prepared by lactic acid bacteria fermentation increased significantly (P<0.05). In conclusion, the color characteristics of the hawthorn fruit leather prepared by lactic acid bacteria fermentation are similar to those of the traditional hawthorn fruit leather.

[0073] Table 3 Color difference of hawthorn fruit leather fermented with lactic acid bacteria

[0074]

[0075] Note: Data are expressed as mean ± standard deviation (n=3); in the same column, identical letters indicate no significant difference (P>0.05), while different letters indicate significant difference (P<0.05).

[0076] 5. Physicochemical properties

[0077] The physicochemical indicators (moisture, ash, and total sugar) of candied hawthorn products were determined according to GB / T 31318-2014 "Candied Hawthorn Products". The results are shown in Table 4. The moisture, ash, and total sugar content of both groups of hawthorn fruit leather met the national standards [moisture content (%) ≤ 30.0; ash content (%) ≤ 1.5; total sugar content (%, calculated as glucose) ≤ 75.0]. In the intestine, sucrose is degraded into glucose and fructose by α-glucosidase, which leads to an increase in blood glucose levels after absorption. Lactic acid bacteria utilize sucrose, glucose, etc., to produce lactic acid and other metabolites, reducing the reducing sugar content. The results showed that the total sugar content of hawthorn fruit leather prepared after lactic acid bacteria fermentation was significantly reduced (P<0.05), with a reduction of 15.4%.

[0078] Table 4 Physicochemical properties of hawthorn fruit leather fermented with lactic acid bacteria

[0079]

[0080] Note: Data are expressed as mean ± standard deviation (n=3); in the same column, identical letters indicate no significant difference (P>0.05), while different letters indicate significant difference (P<0.05).

[0081] 6. Microbiological indicators

[0082] The microbiological indicators (total bacterial count, mold count, and Escherichia coli count) of candied hawthorn products were determined according to GB / T 31318-2014 "Candied Hawthorn Products". The results are shown in Table 5. The total bacterial count, mold count, and Escherichia coli count of both groups of hawthorn leather products met the national standards.

[0083] Table 5 Microbiological Indicators of Lactic Acid Bacteria-Fermented Hawthorn Fruit Leather

[0084]

[0085] Note: × indicates that it was not detected.

[0086] 7. Organic acid content

[0087] Short-chain fatty acids (such as acetic acid, propionic acid, and butyric acid) and organic acids such as lactic acid can lower the pH of the intestinal environment, inhibit the proliferation of harmful bacteria, and thus maintain the balance of the intestinal microecology. The fermentation and nutritional functions of hawthorn fruit leather were assessed by measuring the organic acid content in lactic acid bacteria-fermented fruit leather, and the results are shown in Table 6. Traditional hawthorn fruit leather does not contain lactic acid or butyric acid. After lactic acid bacteria fermentation, the contents of lactic acid, acetic acid, and propionic acid in hawthorn fruit leather increased by 28.0%, 76.8%, and 51.7%, respectively, compared to traditional hawthorn fruit leather.

[0088] The specific detection method is as follows: Weigh 0.2g of hawthorn fruit leather and add it to 0.8mL of distilled water. After homogenization, centrifuge at 12000rpm for 10min and collect the supernatant. Add 100μL of concentrated hydrochloric acid to the supernatant, then add 5mL of diethyl ether and mix thoroughly. Extract at room temperature for 20min and centrifuge at 3500rpm for 10min. Transfer the upper organic phase to another tube, add 500μL of 1M NaOH solution, mix thoroughly, extract at room temperature for 20min and centrifuge at 3500rpm for 10min. Collect the lower aqueous phase, add 100μL of concentrated hydrochloric acid, mix well, and filter the resulting extract through a 0.22μm aqueous filter membrane for high-performance liquid chromatography (HPLC) detection. The detection conditions are as follows: The HPLC column used is a hydrogen ion exchange column (Agilent Hi-Plex H 250, 300×6.5mm). 5 mM sulfuric acid was prepared as mobile phase A, and pure water was used as mobile phase B, with a mixing ratio of 3:2. An autosampler was used for injection, with an injection volume of 25 μL. The flow rate was 0.5 mL / min, the column oven temperature was 55℃, and the UV detector wavelength was 210 nm. Water-soluble fatty acid mixed standard solution (containing acetic acid, propionic acid, and butyric acid) was purchased from the China National Standard Material Network (Catalog No. BWZ6946-2016); lactic acid standard reagent (prepared as a 100 μg / mL aqueous solution) was purchased from Sigma-Aldrich, CAS No. 867-55-0. The peak elution times of the standards were: lactic acid (11.488 min); acetic acid (13.270 min); propionic acid (15.863 min); and butyric acid (19.977 min).

[0089] Table 6. Organic acid content in lactic acid bacteria fermented hawthorn fruit leather

[0090]

[0091]

[0092] Note: Data are expressed as mean ± standard deviation (n=3); in the same column, identical letters indicate no significant difference (P>0.05), while different letters indicate significant difference (P<0.05); × indicates no detection.

[0093] Example 2: Lactic acid bacteria fermented functional oligosaccharide hawthorn fruit leather

[0094] I. Preparation of Konjac Mannan Oligosaccharide Hawthorn Fruit Leather by Lactic Acid Bacteria Fermentation

[0095] 1. Raw material pretreatment: Select 100g of fresh hawthorn as raw material, wash and drain the water.

[0096] 2. Preparation: Dissolve 35g of konjac mannan oligosaccharide (purchased from Xi'an Yuansen Biotechnology Co., Ltd., CAS No. 37220-17-0) and 35g of xylitol (purchased from Shandong Futian Pharmaceutical Co., Ltd., CAS No. 63-42-3) in 55g of water, then add the hawthorn fruit treated in step 1.

[0097] 3. Steaming and pulping: After pouring the mixture obtained in step 2 into a container, place the container in a pressure cooker (pressure of 70 kPa, add 300g of water to the pot) and steam for 25 minutes, then pulp evenly.

[0098] 4. Lactic acid bacteria fermentation: Inoculate 3g of lactic acid bacteria powder into the crushed material obtained in step 3, and anaerobic ferment at 38℃ for 4 hours. Then, pulp and remove seeds from the fermented material and filter it with a 20-mesh filter.

[0099] 5. Spreading: Pour the fruit pulp obtained from filtering in step 4 onto the aluminum foil, fix the height between the scraper and the aluminum foil (3-5mm), and drag the aluminum foil to complete the spreading.

[0100] 6. Drying: After completing step 5, place the spread fruit pulp into the oven, set the oven temperature to 65℃ for both the top and bottom heat, and bake for 7 hours until the moisture content of the sample drops below 30%.

[0101] 7. Removing the sheet: Peel the dried fruit leather from the foil and cut it.

[0102] 8. Packaging and Warehousing: Roll up the cut fruit leather and pack it into storage.

[0103] II. Parameter Detection

[0104] Sensory evaluation, appearance, texture, color difference, physicochemical properties, microbiological indicators and organic acid content of lactic acid bacteria fermented konjac mannan oligosaccharide hawthorn fruit leather were tested according to the method described in Part II of Example 1.

[0105] The sensory evaluation results are shown in Table 7. As shown in Table 7, the lactic acid bacteria fermented konjac mannan oligosaccharide hawthorn fruit leather showed no significant difference in color, texture, taste, and total score compared to traditional hawthorn fruit leather (sucrose hawthorn fruit leather prepared without lactic acid bacteria fermentation, whose preparation method is the same as step one in Example 1, the only difference being the absence of probiotics) (P>0.05). This indicates that the lactic acid bacteria fermented konjac mannan oligosaccharide hawthorn fruit leather prepared in Example 2 can highly simulate the sensory quality of traditional hawthorn fruit leather.

[0106] Table 7. Comparison of sensory evaluation scores between lactic acid bacteria fermented konjac mannan oligosaccharide hawthorn fruit leather and traditional hawthorn fruit leather.

[0107]

[0108] Note: Data marked with different letters in the same column indicate significant differences (P<0.05). The significance analysis of the data between groups was performed using Duncan(D) multiple comparisons in one-way ANOVA.

[0109] The results of the morphological analysis showed that the color and transparency of the lactic acid bacteria fermented konjac mannan oligosaccharide hawthorn fruit leather were good, and the appearance was similar to that of traditional hawthorn fruit leather.

[0110] The textural analysis results are shown in Table 8. Table 8 shows that the hardness and adhesiveness of the lactic acid bacteria-fermented konjac mannan oligosaccharide hawthorn fruit leather are significantly improved compared to traditional hawthorn fruit leather (P<0.05). This is attributed to the inherent texture characteristics of konjac mannan oligosaccharide and the metabolic products generated during lactic acid bacteria fermentation. Table 8 also shows that the cohesiveness, elasticity, and chewiness of the lactic acid bacteria-fermented konjac mannan oligosaccharide hawthorn fruit leather are not significantly different from those of traditional hawthorn fruit leather (P>0.05). In conclusion, the textural properties of the lactic acid bacteria-fermented konjac mannan oligosaccharide hawthorn fruit leather are similar to those of traditional hawthorn fruit leather.

[0111] Table 8. Lactic acid bacteria fermentation of konjac mannan oligosaccharide hawthorn fruit leather composition

[0112]

[0113] Note: Data are expressed as mean ± standard deviation (n=3); in the same column, identical letters indicate no significant difference (P>0.05), while different letters indicate significant difference (P<0.05).

[0114] The color difference test results are shown in Table 9. As can be seen from Table 9, in terms of L and a values, there was no significant difference between the lactic acid bacteria fermented konjac mannan oligosaccharide hawthorn fruit leather and the traditional hawthorn fruit leather (P>0.05). However, in terms of b and ΔE, the lactic acid bacteria fermented konjac mannan oligosaccharide hawthorn fruit leather was significantly higher than that of the traditional hawthorn fruit leather (P<0.05). In conclusion, the color characteristics of the lactic acid bacteria fermented konjac mannan oligosaccharide hawthorn fruit leather are quite similar to those of the traditional hawthorn fruit leather.

[0115] Table 9 Color Difference of Lactic Acid Bacteria Fermented Konjac Manna Oligosaccharide Peel

[0116]

[0117] Note: Data are expressed as mean ± standard deviation (n=3); in the same column, identical letters indicate no significant difference (P>0.05), while different letters indicate significant difference (P<0.05).

[0118] The physicochemical properties were tested and the results are shown in Table 10. As can be seen from Table 10, the moisture, ash, and total sugar content of both groups of hawthorn fruit leather met the national standards [moisture content (%) ≤ 30.0; ash content (%) ≤ 1.5; total sugar content (%, calculated as glucose) ≤ 75.0]. The total sugar content of the konjac mannan oligosaccharide hawthorn fruit leather prepared after lactic acid bacteria fermentation was significantly lower than that of traditional hawthorn fruit leather (P<0.05), with a reduction of 76.7%.

[0119] Table 10 Physicochemical properties of lactic acid bacteria fermented konjac mannan oligosaccharide and peony bark

[0120]

[0121] Note: Data are expressed as mean ± standard deviation (n=3); in the same column, identical letters indicate no significant difference (P>0.05), while different letters indicate significant difference (P<0.05).

[0122] The results of the microbial index tests are shown in Table 11. As shown in Table 11, the total bacterial count, mold count, and Escherichia coli count of both groups of fruit leather met the national standards.

[0123] Table 11 Microbiological Indicators of Lactic Acid Bacteria Fermented Konjac Mannan Oligosaccharide Hawthorn Fruit Leather

[0124]

[0125] Note: × indicates that it was not detected.

[0126] The organic acid content is shown in Table 12. The content of lactic acid, acetic acid, and propionic acid in the konjac mannan oligosaccharide hawthorn fruit leather prepared after lactic acid bacteria fermentation increased by 42.0%, 808.5%, and 23.7%, respectively, compared with the traditional hawthorn fruit leather.

[0127] Table 12 Organic Acid Content in Lactic Acid Bacteria Fermented Konjac Mannan Oligosaccharide and Hawthorn Fruit Leather

[0128]

[0129] Note: Data are expressed as mean ± standard deviation (n=3); in the same column, identical letters indicate no significant difference (P>0.05), while different letters indicate significant difference (P<0.05); × indicates no detection.

[0130] Example 3: Hawthorn Fruit Leather Fermented with Lactobacillus plantarum Functional Oligosaccharides

[0131] Example 3 provides a hawthorn fruit leather fermented with *Lactobacillus plantarum* and functional oligosaccharides, prepared using a method essentially consistent with that of Example 2, except that 3g of *Lactobacillus plantarum* powder (10 billion live bacteria / g, purchased from Xi'an Xinshan Biotechnology Co., Ltd., catalog number XS-0103) is used instead of 3g of lactic acid bacteria powder. The sensory qualities of the prepared *Lactobacillus plantarum* fermented functional oligosaccharides hawthorn fruit leather, including color, texture, and taste, showed no significant difference from traditional hawthorn fruit leather (P>0.05), and its texture and color difference were similar to traditional hawthorn fruit leather. The moisture, ash, total sugar content, and microbiological indicators of the *Lactobacillus plantarum* fermented functional oligosaccharides hawthorn fruit leather all met national standards, with the total sugar content decreasing by 26.7% compared to traditional hawthorn fruit leather. The contents of lactic acid, acetic acid, and propionic acid in the fermented hawthorn fruit leather increased by 31.0%, 345.3%, and 45.6%, respectively, compared to traditional hawthorn fruit leather.

[0132] Example 4: Fermentation of functional oligosaccharides by lactic acid bacteria and bifidobacteria in hawthorn fruit leather

[0133] Example 4 provides a functional oligosaccharide hawthorn fruit leather fermented with lactic acid bacteria and bifidobacteria, which is prepared in a manner that is basically the same as that provided in Example 2, except that 3g of mixed bacterial powder is used instead of 3g of lactic acid bacteria powder.

[0134] The mixed bacterial powder is obtained by mixing lactic acid bacteria powder and bifidobacteria powder in a mass ratio of 1:1.

[0135] The sensory qualities of the prepared hawthorn fruit leather fermented with functional oligosaccharides by lactic acid bacteria and bifidobacteria, including color, texture, and taste, showed no significant difference from those of traditional hawthorn fruit leather (P>0.05), and the texture and color difference were similar to those of traditional hawthorn fruit leather. The moisture, ash, total sugar content, and microbiological indicators of the hawthorn fruit leather fermented with functional oligosaccharides by lactic acid bacteria and bifidobacteria all met national standards, with the total sugar content decreasing by 79.3% compared to traditional hawthorn fruit leather. The contents of lactic acid, acetic acid, and propionic acid in the hawthorn fruit leather fermented with lactic acid bacteria and bifidobacteria increased by 46.0%, 728.4%, and 30.8%, respectively, compared to traditional hawthorn fruit leather.

[0136] Example 5: Yeast fermentation of hawthorn fruit leather

[0137] Example 5 provides a yeast-fermented hawthorn fruit leather preparation method that is basically the same as that provided in Example 1, except that 5g of yeast powder is used instead of 2g of lactic acid bacteria powder.

[0138] The prepared yeast-fermented hawthorn fruit leather exhibits similar sensory qualities (color, texture, and taste) as well as similar texture and color difference to traditional hawthorn fruit leather. The moisture, ash, total sugar content, and microbiological indicators of the yeast-fermented hawthorn fruit leather all meet national standards, with the total sugar content decreasing by 22.5% compared to traditional hawthorn fruit leather. The content of lactic acid, acetic acid, and propionic acid in the yeast-fermented hawthorn fruit leather increases by 17.0%, 53.7%, and 11.2%, respectively, compared to traditional hawthorn fruit leather.

Claims

1. A method for preparing hawthorn fruit leather, comprising the following steps: using hawthorn as raw material, fermenting with probiotics to obtain hawthorn fruit leather; The probiotic is lactic acid bacteria powder; or, the probiotic is a compound bacteria obtained by mixing lactic acid bacteria powder and bifidobacteria in a mass ratio of 1:

1. The lactic acid bacteria powder is obtained by mixing Lactobacillus bulgaricus, Streptococcus thermophilus, Lactobacillus acidophilus, Lactobacillus plantarum and Lactobacillus casei in a mass ratio of 1:1:1:1:

1. The raw materials also include sugar, sugar alcohols, and water; The sugar is konjac mannan oligosaccharide; The sugar alcohol is xylitol; The mass ratio of hawthorn, water, sugar, sugar alcohol, and probiotics is 100:50-70:10-70:1-5.

2. The method of claim 1, wherein: The fermentation is anaerobic fermentation.

3. Hawthorn fruit leather prepared by the method described in claim 1 or 2.

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