A prebiotic-rich kombucha-fermented oak jelly and its preparation method

Abstract

This invention discloses a kombucha-fermented acorn jelly rich in prebiotics, comprising, per 100 parts by weight: 40-70 parts by weight of acorn fermentation broth, 3-15 parts by weight of isomaltooligosaccharide, 1-16 parts by weight of purple sweet potato anthocyanin aqueous extract, 6-22 parts by weight of a composite coagulant, and the remainder being water. The invention also discloses its preparation method. This invention reduces the bitterness and astringency of acorns and enriches their flavor through kombucha fermentation; by adding prebiotics (purple sweet potato anthocyanins and isomaltooligosaccharide) for coloring and flavoring, it enhances both the sensory quality and health benefits of the acorn jelly; and by preparing a low-temperature composite coagulant, which eliminates the need for heating, it maximizes the preservation of probiotic activity in the jelly, further enhancing its intestinal health-improving effects. The method of this invention yields a fermented acorn jelly product that combines prebiotics and probiotics. This invention provides technical support for the development of high-value-added acorn foods.

Description

Technical Field

[0001] This invention relates to the field of food processing, specifically to a kombucha-fermented oak jelly rich in prebiotics and its preparation method. Background Technology

[0002] Castanopsis sclerophylla is one of my country's important forest food resources, possessing antioxidant, anti-inflammatory, cholesterol-lowering, brain function-delaying, cooling, skin-moisturizing, weight-loss, and anti-diarrheal effects. Castanopsis sclerophylla has a long history as a food product in my country, and currently, its main product forms include castanopsis sclerophylla wine (CN115521843A), castanopsis sclerophylla vinegar (CN108641889A), castanopsis sclerophylla vermicelli (CN108077902A), and castanopsis sclerophylla tofu (CN101258912A).

[0003] Currently, the overall processing technology of the acorn industry remains relatively simple, with limited product variety and low added value, making it difficult to effectively improve industry efficiency. Furthermore, acorns contain a significant amount of tannins, giving them a bitter and astringent taste. Therefore, processing often requires multiple soaking and washing processes to remove the bitterness and astringency, inevitably leading to the loss of soluble nutrients, significant water waste, and time and labor costs, severely restricting processing efficiency. Summary of the Invention

[0004] The purpose of this invention is to provide a prebiotic-rich kombucha-fermented oak jelly and its preparation method, in order to overcome the shortcomings of the prior art.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] A kombucha-fermented sago jelly rich in prebiotics, comprising, per 100 parts by weight: 40-70 parts by weight of sago fermentation liquid, 3-15 parts by weight of isomaltooligosaccharide, 1-16 parts by weight of purple sweet potato anthocyanin aqueous extract, 6-22 parts by weight of compound coagulant, and the remainder being water.

[0007] Furthermore, per 100 parts by weight, it includes: 45-55 parts by weight of bitter oak fermentation broth, 6-12 parts by weight of isomaltooligosaccharide, 4-12 parts by weight of purple sweet potato anthocyanin aqueous extract, 10-18 parts by weight of composite coagulant, and the remainder is water.

[0008] Furthermore, per 100 parts by weight, it includes: 55 parts by weight of bitter oak fermentation broth, 12 parts by weight of isomaltooligosaccharide, 8 parts by weight of purple sweet potato anthocyanin aqueous extract, 14 parts by weight of composite coagulant, and the remainder is water.

[0009] Furthermore, the cassia fermentation broth is prepared by the following steps:

[0010] (1) Preparation of bitter acorn pulp filtrate: After peeling and washing fresh bitter acorn fruits, mix them with water and pulp to obtain bitter acorn pulp; filter the bitter acorn pulp with multiple layers of gauze to obtain bitter acorn pulp filtrate.

[0011] (2) Sterilization of bitter oak pulp filtrate: Sterilize the bitter oak pulp filtrate and cool it;

[0012] (3) Fermentation of bitter oak pulp filtrate: Kombucha is inoculated into the sterilized and cooled bitter oak pulp filtrate and fermented to obtain bitter oak fermentation liquid.

[0013] Furthermore, in step (1), the mass ratio of peeled and washed Castanopsis sclerotium fruit to water is 1:5-1:25; in step (2), sterilize at 80-110℃ for 10-30 min and cool to room temperature; in step (3), inoculate kombucha into the sterilized and cooled Castanopsis sclerotium slurry filtrate at an inoculation rate of 1v / v%-4v / v%, and the fermentation conditions are: stand, fermentation temperature of 30℃-38℃, and fermentation time of 12 h-72 h.

[0014] Furthermore, the purple sweet potato anthocyanin aqueous extract is prepared by the following steps:

[0015] (1) Preparation of purple sweet potato pulp: Peel and wash fresh purple sweet potatoes, mix them with water and pulp to obtain purple sweet potato pulp; filter the purple sweet potato pulp with multiple layers of gauze to obtain purple sweet potato pulp filtrate;

[0016] (2) Centrifugation: Centrifuge the purple sweet potato pulp filtrate, collect the supernatant, and obtain the purple sweet potato anthocyanin aqueous extract.

[0017] Furthermore, in step (1), the mass ratio of peeled and washed purple sweet potatoes to water is 1:0.25-1.5; in step (2), the centrifugation speed is 5000-8000 rpm and the centrifugation time is 10-20 min.

[0018] Furthermore, the composite coagulant is prepared by the following steps:

[0019] (1) Preparation of fig seed pectin solution: Fresh or dried fig seeds are mixed with water, gently rubbed, and filtered through multiple layers of gauze to obtain filtrate, which is fig seed pectin solution;

[0020] (2) Preparation of composite coagulant: Konjac powder and wild lotus root powder were added to the pectin solution of fig seeds and mixed well to obtain composite coagulant.

[0021] Furthermore, in step (1), the seeds of *Ficus pumila* are mixed with water at a mass ratio of 1:10-1:20, and the mass of the seeds of *Ficus pumila* is based on the mass of dried seeds of *Ficus pumila*. The mixture is gently rubbed by hand, 20-40 times per minute, for 3-15 minutes. In step (2), the mass ratio of seeds of *Ficus pumila*, konjac powder and wild lotus root powder is 3-5:7-10:0.15-0.25, and the mass of the seeds of *Ficus pumila* is based on the mass of dried seeds of *Ficus pumila*.

[0022] Furthermore, in step (2), the mass ratio of fig seeds, konjac powder and wild lotus root powder is 5:10:0.2, and the mass of fig seeds is based on the mass of dried fig seeds.

[0023] The preparation method of the above-mentioned prebiotic-rich kombucha fermented oak jelly includes the following steps:

[0024] (1) Preparation of bitter oak fermentation liquid: Peel and wash fresh bitter oak fruit, add water to make pulp, filter, sterilize and cool, and then inoculate with kombucha to ferment and obtain bitter oak fermentation liquid;

[0025] (2) Flavoring: Add isomaltooligosaccharide to the bitter oak fermentation liquid to adjust the sweetness and acidity of the bitter oak fermentation liquid, and obtain the flavored bitter oak fermentation liquid;

[0026] (3) Color adjustment: Peel and wash fresh purple sweet potatoes, add water to make pulp, filter, centrifuge, collect the supernatant to obtain purple sweet potato anthocyanin aqueous extract; add purple sweet potato anthocyanin aqueous extract to flavored bitter oak fermentation liquid to adjust the color, and obtain flavored and flavored bitter oak fermentation liquid.

[0027] (4) Preparation of composite coagulant: Fresh or dried fig seeds are rubbed with water and filtered to obtain the filtrate, which is the fig seed pectin solution. Konjac powder and wild lotus root powder are added to the fig seed pectin solution and mixed well to obtain the composite coagulant.

[0028] (5) Solidification and shaping: Mix the composite coagulant, water and the flavored and colored sago fermentation liquid evenly, and solidify at low temperature to obtain the kombucha fermented sago jelly rich in prebiotics.

[0029] Furthermore, in step (5), the low-temperature solidification conditions are: standing, solidification temperature of 2-15℃, and solidification time of 20-60 min.

[0030] The beneficial effects of this invention are:

[0031] This invention first involves pulping and filtering fresh, peeled acorns to obtain a bitter acorn pulp filtrate, sterilizing it, and then inoculating it with kombucha for fermentation. Next, isomaltooligosaccharides are added to the fermented acorn filtrate to adjust the sweetness and acidity. Then, fresh purple sweet potatoes are peeled, pulped, filtered, centrifuged, and added to the fermented acorn filtrate for color adjustment. Finally, creeping fig seeds are kneaded, filtered, and then mixed evenly with wild lotus root powder and konjac powder to prepare a composite coagulant, which is added to the fermented acorn filtrate and solidified at low temperature to obtain a kombucha-fermented bitter acorn jelly rich in prebiotics. This invention reduces the bitterness of acorns and enriches their flavor through kombucha fermentation; by adding prebiotics (purple sweet potato anthocyanins and isomaltooligosaccharides) for color and flavor adjustment, it enhances the sensory quality and health benefits of the bitter acorn jelly; and by preparing a low-temperature composite coagulant, which eliminates the need for heating, it maximizes the activity of probiotics in the jelly, further enhancing its intestinal health-improving effects. This invention provides a fermented acorn jelly product containing both prebiotics and probiotics. This invention offers technical support for the development of high-value-added acorn foods. Its specific advantages are as follows:

[0032] 1. In the processing method of this invention, the microbial strain used for fermenting the slurry filtrate of acorn is kombucha, which is rich in probiotics such as yeast and lactic acid bacteria. It can rapidly multiply using sugars such as starch in acorn, eliminating the need for additional sucrose or saccharification steps. The operation is simple, and the fermentation process synthesizes various organic acids and esters, as well as degrading tannins, effectively reducing the astringency and bitterness of acorn, enriching its flavor, and improving the sensory quality of the product. Furthermore, kombucha, once in the intestines, can enhance the body's immunity, strengthen the intestinal microecological balance, and improve the functional activity of the product.

[0033] 2. In the processing method of this invention, purple sweet potato anthocyanin aqueous extract is added to the bitter oak fermentation broth to introduce the anthocyanins. Purple sweet potato anthocyanins are a type of natural water-soluble pigment. The kombucha fermentation of the bitter oak pulp filtrate provides an acidic environment for the anthocyanins, which significantly improves their stability. In this acidic environment, the anthocyanins exhibit a bright and appealing purplish-red color, significantly enhancing the product's color score. Simultaneously, purple sweet potato anthocyanins are a prebiotic with significant antioxidant and intestinal regulatory activities, which can significantly enhance the product's functional activity.

[0034] 3. In the processing method of this invention, by adding isomaltooligosaccharide, the fermentation broth of acorn is adjusted to a suitable sweet and sour level. The sweetness of isomaltooligosaccharide and the sourness of the organic acids in the fermentation broth of acorn provide consumers with a sweet and sour taste, enriching the flavor layers of acorn jelly and significantly improving the product's texture and palatability. At the same time, isomaltooligosaccharide is a prebiotic that can regulate intestinal flora.

[0035] 4. In the processing method of this invention, a low-temperature composite coagulant is formulated using natural food ingredients such as fig seed, konjac flour, and wild lotus root flour, which do not require heating to melt and solidify. This not only gives the bitter oak jelly a chewy gel structure, but its heat-free, low-temperature coagulation characteristic also maximizes the protection of probiotic activity, further enhancing its effect on improving intestinal health. Furthermore, it simplifies the processing and saves production costs. At the same time, the abundant natural pectin in the above three ingredients is also a type of dietary fiber with significant intestinal regulatory activity.

[0036] 5. The kombucha-fermented acorn jelly rich in prebiotics prepared by this invention uses only natural food raw materials, without any added chemical additives. The production process is simple, with low processing costs, making it suitable for industrial production. While preserving the nutritional value of acorn jelly to the greatest extent possible (as the fruit does not require multiple soaking and washing, reducing the loss of soluble nutrients), probiotics (kombucha) and prebiotics (purple sweet potato anthocyanins and isomaltooligosaccharides) are introduced. This results in a functional jelly that significantly reduces the bitterness of acorn jelly, possesses a rich fermented fruity aroma, a purplish-red color, an appealing appearance, a sweet and sour taste, and a smooth texture. Compared to ordinary jellies on the market, it has significant free radical scavenging ability and intestinal flora regulation function. This product is suitable for consumption by all types of people. This invention improves the processing performance of acorn jelly, enriches the food varieties made from acorn jelly, and is conducive to the high-value development of the acorn jelly industry. Attached Figure Description

[0037] Figure 1 The effect of the amount of strychnos nux-vomica fermentation liquid added on the sensory properties of kombucha-fermented strychnos nux-vomica jelly rich in prebiotics.

[0038] Figure 2 The effect of the amount of isomaltooligosaccharide added on the sensory properties of kombucha-fermented oak jelly rich in prebiotics.

[0039] Figure 3 The effect of the amount of purple sweet potato anthocyanin aqueous extract added on the sensory properties of kombucha-fermented oak jelly rich in prebiotics.

[0040] Figure 4 The effect of the amount of compound coagulant added on the sensory properties of kombucha-fermented oak jelly rich in prebiotics.

[0041] Figure 5 The image shows the appearance of the prebiotic-rich kombucha fermented oak jelly prepared in Example 2.

[0042] Figure 6 The total phenol content of each jelly sample was determined.

[0043] Figure 7 The antioxidant activity of each jelly sample was determined. Detailed Implementation

[0044] The present invention will be further described below with reference to the accompanying drawings and embodiments. The following embodiments do not limit the scope of the present invention, and the materials, equipment, etc. used are all commercially available unless otherwise specified.

[0045] Example 1: Process optimization of prebiotic-rich kombucha-fermented oak jelly

[0046] 1. Single-factor experiment

[0047] (1) Sensory evaluation criteria for kombucha-fermented oak jelly rich in prebiotics

[0048] The sensory evaluation team consisted of 10 members (5 male and 5 female graduate students majoring in food science and engineering, all of whom had received training in food sensory evaluation). The evaluation indicators included appearance, color, taste, flavor and texture. The specific evaluation content is shown in Table 1.

[0049] Table 1 Sensory evaluation criteria for prebiotic-rich kombucha-fermented oak jelly

[0050]

[0051] (2) Effect of the amount of bitter oak fermentation liquid added on the sensory properties of kombucha-fermented bitter oak jelly rich in prebiotics

[0052] A. Composition

[0053] Based on 100 parts by weight, the fermentation broth of Castanopsis sclerophylla was prepared as follows: 40 parts by weight, 50 parts by weight, 60 parts by weight, 70 parts by weight, 6 parts by weight of isomaltooligosaccharide, 4 parts by weight of purple sweet potato anthocyanin aqueous extract, 14 parts by weight of composite coagulant, and the remainder being purified water.

[0054] B. Preparation method

[0055] (a) Preparation of bitter acorn fermentation broth: Select fresh bitter acorn fruits, peel and wash them, accurately weigh 100 g, add 900 g of purified water and blend (Midea MJ-BL80Y21 high-speed blender, three speeds, 20 s / min, 10 min) to obtain bitter acorn slurry; filter the bitter acorn slurry through 8 layers of gauze (model 21s×32s) to obtain bitter acorn slurry filtrate; sterilize the bitter acorn slurry filtrate at 80℃ for 30 min, cool to room temperature, and then inoculate kombucha (Changsha Hepu Biotechnology Co., Ltd., liquid) into the sterilized and cooled bitter acorn slurry filtrate at an inoculation amount of 3v / v% (volume of kombucha / volume of sterilized and cooled bitter acorn slurry filtrate × 100%), and incubate at 37℃ for 36 h to obtain bitter acorn fermentation broth.

[0056] (b) Flavoring: Add 60 g of isomaltooligosaccharide (Zhejiang Nuoyi Biotechnology Co., Ltd.) to 400 g, 500 g, 600 g and 700 g of bitter oak fermentation liquid respectively, stir evenly and adjust the sweetness and sourness to obtain the flavored bitter oak fermentation liquid.

[0057] (c) Color adjustment: Select fresh purple sweet potatoes, peel and wash them, accurately weigh 600 g, add 400 g of purified water and blend (Midea MJ-BL80Y21 high-speed blender, three speeds, 20 s / min, 10 min) to obtain purple sweet potato pulp; filter the purple sweet potato pulp through 8 layers of gauze (model 21s×32s) to obtain purple sweet potato pulp filtrate; centrifuge the purple sweet potato pulp filtrate at 8000 rpm for 10 min, collect the supernatant to obtain purple sweet potato anthocyanin aqueous extract; add 40 g of purple sweet potato anthocyanin aqueous extract to 460 g, 560 g, 660 g, and 760 g of flavored bitter oak fermentation liquid respectively, stir evenly to adjust the color, and obtain flavored and color-adjusted bitter oak fermentation liquid.

[0058] (d) Preparation of composite coagulant: Accurately weigh 10 g of fig seeds (fresh or dried, dried in this example), add 170 g of purified water, gently rub by hand (about 20 times per minute, rubbing for about 5 minutes), then filter through 8 layers of gauze (model 21s×32s) to obtain filtrate, which is fig seed pectin solution. Then add 20 g of konjac powder (about 80 mesh) and 0.4 g of wild lotus root powder (about 80 mesh) to the fig seed pectin solution, mix well and obtain composite coagulant.

[0059] (e) Jelly Formation: 140 g of the composite coagulant was mixed evenly with 360 g, 260 g, 160 g, and 60 g of purified water and 500 g, 600 g, 700 g, and 800 g of color- and flavored acorn fermentation liquid, respectively (i.e., 140 g of the composite coagulant was mixed evenly with 360 g of purified water and 500 g of color- and flavored acorn fermentation liquid, 140 g of the composite coagulant was mixed evenly with 260 g of purified water and 600 g of color- and flavored acorn fermentation liquid, and so on). The mixture was then solidified at 4℃ for 30 min to produce a prebiotic-rich kombucha-fermented acorn jelly. The effect of the amount of acorn fermentation liquid added on the sensory properties of the jelly was investigated. Results are shown below. Figure 1 .

[0060] from Figure 1 It can be seen that the amount of acorn fermentation liquid added can significantly affect the sensory score of the jelly. When the amount of acorn fermentation liquid added is too low, the acorn flavor in the jelly is not strong enough and its characteristics are not obvious. When the amount of acorn fermentation liquid added is higher than 50wt%, the sensory score of the jelly begins to decline, the taste becomes more sour, the texture deteriorates, and consumer acceptance is lower. Therefore, 50wt% is selected as the optimal amount of acorn fermentation liquid added, at which point the jelly has better sensory properties.

[0061] (3) Effect of the amount of isomaltooligosaccharide added on the sensory properties of kombucha-fermented oak jelly rich in prebiotics

[0062] A. Composition

[0063] Based on 100 parts by weight, the following components were used: 50 parts by weight of bitter oak fermentation broth, 3 parts by weight, 6 parts by weight, 9 parts by weight, 12 parts by weight, and 15 parts by weight of isomaltooligosaccharides, 4 parts by weight of purple sweet potato anthocyanin aqueous extract, 14 parts by weight of composite coagulant, and the remainder being purified water.

[0064] B. Preparation method

[0065] (a) Preparation of bitter acorn fermentation broth: Select fresh bitter acorn fruits, peel and wash them, accurately weigh 100 g, add 900 g of purified water and blend (Midea MJ-BL80Y21 high-speed blender, three speeds, 20 s / min, 10 min) to obtain bitter acorn slurry; filter the bitter acorn slurry through 8 layers of gauze (model 21s×32s) to obtain bitter acorn slurry filtrate; sterilize the bitter acorn slurry filtrate at 80℃ for 30 min, cool to room temperature, and then inoculate kombucha (Changsha Hepu Biotechnology Co., Ltd., liquid) into the sterilized and cooled bitter acorn slurry filtrate at an inoculation amount of 3v / v% (volume of kombucha / volume of sterilized and cooled bitter acorn slurry filtrate × 100%), and incubate at 37℃ for 36 h to obtain bitter acorn fermentation broth.

[0066] (b) Flavoring: Add 30 g, 60 g, 90 g, 120 g and 150 g of isomaltooligosaccharide (Zhejiang Nuoyi Biotechnology Co., Ltd.) to 500 g of bitter oak fermentation liquid, stir evenly and adjust the sweetness and sourness to obtain the flavored bitter oak fermentation liquid.

[0067] (c) Color adjustment: Select fresh purple sweet potatoes, peel and wash them, accurately weigh 600 g, add 400 g of purified water and blend (Midea MJ-BL80Y21 high-speed blender, three speeds, 20 s / min, 10 min) to obtain purple sweet potato pulp; filter the purple sweet potato pulp through 8 layers of gauze (model 21s×32s) to obtain purple sweet potato pulp filtrate; centrifuge the purple sweet potato pulp filtrate at 8000 rpm for 10 min, collect the supernatant to obtain purple sweet potato anthocyanin aqueous extract; add 40 g of purple sweet potato anthocyanin aqueous extract to 530 g, 560 g, 590 g, 620 g and 650 g of flavored bitter oak fermentation liquid respectively, stir evenly to adjust the color, and obtain flavored and color-adjusted bitter oak fermentation liquid.

[0068] (d) Preparation of composite coagulant: Accurately weigh 10 g of fig seeds (fresh or dried, dried in this example), add 170 g of purified water, gently rub by hand (about 20 times per minute, rubbing for about 5 minutes), then filter through 8 layers of gauze (model 21s×32s) to obtain filtrate, which is fig seed pectin solution. Then add 20 g of konjac powder (about 80 mesh) and 0.4 g of wild lotus root powder (about 80 mesh) to the fig seed pectin solution, mix well and obtain composite coagulant.

[0069] (e) Jelly Formation: 140 g of the composite coagulant was mixed evenly with 290 g, 260 g, 230 g, 200 g, and 170 g of purified water and 570 g, 600 g, 630 g, 660 g, and 690 g of coloring and flavoring acorn fermentation liquid, respectively. The mixture was then solidified at 4°C for 30 min to produce prebiotic-rich kombucha-fermented acorn jelly. The effect of isomaltooligosaccharide addition on the sensory properties of the jelly was investigated. Results are shown below. Figure 2 .

[0070] from Figure 2 As can be seen, the amount of isomaltooligosaccharide added significantly affects the sensory score of the jelly, showing a trend of first increasing and then decreasing. When the amount of isomaltooligosaccharide added is low, the jelly flavor is more acidic, which has a significant impact on sensory quality; when the amount added is higher than 9 wt%, the sensory score of the jelly begins to decrease, and the flavor becomes sweeter. Therefore, 9 wt% is selected as the optimal amount of isomaltooligosaccharide added, at which point the jelly has better sensory properties.

[0071] (4) Effect of the amount of purple sweet potato anthocyanin aqueous extract added on the sensory properties of kombucha-fermented oak jelly rich in prebiotics

[0072] A. Composition

[0073] Based on 100 parts by weight, the following components were used: 50 parts by weight of bitter oak fermentation broth, 9 parts by weight of isomaltooligosaccharide, 1 part by weight of purple sweet potato anthocyanin aqueous extract, 4 parts by weight, 8 parts by weight, 12 parts by weight, and 16 parts by weight, respectively; 14 parts by weight of composite coagulant; and the remainder was purified water.

[0074] B. Preparation method

[0075] (a) Preparation of bitter acorn fermentation broth: Select fresh bitter acorn fruits, peel and wash them, accurately weigh 100 g, add 900 g of purified water and blend (Midea MJ-BL80Y21 high-speed blender, three speeds, 20 s / min, 10 min) to obtain bitter acorn slurry; filter the bitter acorn slurry through 8 layers of gauze (model 21s×32s) to obtain bitter acorn slurry filtrate; sterilize the bitter acorn slurry filtrate at 80℃ for 30 min, cool to room temperature, and then inoculate kombucha (Changsha Hepu Biotechnology Co., Ltd., liquid) into the sterilized and cooled bitter acorn slurry filtrate at an inoculation amount of 3v / v% (volume of kombucha / volume of sterilized and cooled bitter acorn slurry filtrate × 100%), and incubate at 37℃ for 36 h to obtain bitter acorn fermentation broth.

[0076] (b) Flavoring: Add 90 g of isomaltooligosaccharide (Zhejiang Nuoyi Biotechnology Co., Ltd.) to 500 g of bitter oak fermentation liquid, stir evenly to adjust the sweetness and sourness, and obtain the flavored bitter oak fermentation liquid.

[0077] (c) Color adjustment: Select fresh purple sweet potatoes, peel and wash them, accurately weigh 600 g, add 400 g of purified water and blend (Midea MJ-BL80Y21 high-speed blender, three speeds, 20 s / min, 10 min) to obtain purple sweet potato pulp; filter the purple sweet potato pulp through 8 layers of gauze (model 21s×32s) to obtain purple sweet potato pulp filtrate; centrifuge the purple sweet potato pulp filtrate at 8000 rpm for 10 min, collect the supernatant to obtain purple sweet potato anthocyanin aqueous extract; add 10 g, 40 g, 80 g, 120 g, and 160 g of purple sweet potato anthocyanin aqueous extract to 590 g of flavored bitter oak fermentation liquid, stir evenly to adjust the color, and obtain flavored and flavored bitter oak fermentation liquid.

[0078] (d) Preparation of composite coagulant: Accurately weigh 10 g of fig seeds (fresh or dried, dried in this example), add 170 g of purified water, gently rub by hand (about 20 times per minute, rubbing for about 5 minutes), then filter through 8 layers of gauze (model 21s×32s) to obtain filtrate, which is fig seed pectin solution. Then add 20 g of konjac powder (about 80 mesh) and 0.4 g of wild lotus root powder (about 80 mesh) to the fig seed pectin solution, mix well and obtain composite coagulant.

[0079] (e) Jelly Formation: 140 g of the composite coagulant was mixed evenly with 260 g, 230 g, 190 g, 150 g, and 110 g of purified water and 600 g, 630 g, 670 g, 710 g, and 750 g of color- and flavor-adjusted Castanopsis sclerophylla fermentation liquid, respectively. The mixture was then solidified at 4℃ for 30 min to produce prebiotic-rich kombucha-fermented Castanopsis sclerophylla jelly. The effect of the amount of purple sweet potato anthocyanin aqueous extract added on the sensory properties of the jelly was investigated. Results are shown below. Figure 3 .

[0080] from Figure 3 As can be seen, the amount of purple sweet potato anthocyanin aqueous extract added has a significant impact on the sensory score of the jelly. When the amount of purple sweet potato anthocyanin aqueous extract added is insufficient, the jelly is too light in color and has poor gloss; when the amount of purple sweet potato anthocyanin aqueous extract added is higher than 8 wt%, the sensory score of the jelly decreases and the color becomes too dark. Therefore, 8 wt% is selected as the optimal amount of purple sweet potato anthocyanin aqueous extract added, at which point the jelly has better sensory properties.

[0081] (5) Effect of compound coagulant dosage on sensory properties of kombucha-fermented oak jelly rich in prebiotics

[0082] (5.1) Determination of the amount of composite coagulant added

[0083] A. Composition

[0084] Based on 100 parts by weight, the following components were used: 50 parts by weight of bitter oak fermentation broth, 9 parts by weight of isomaltooligosaccharide, 8 parts by weight of purple sweet potato anthocyanin aqueous extract, and the composite coagulant was prepared in the following proportions: 6 parts by weight, 10 parts by weight, 14 parts by weight, 18 parts by weight, and 22 parts by weight, with the remainder being purified water.

[0085] B. Preparation method

[0086] (a) Preparation of bitter acorn fermentation broth: Select fresh bitter acorn fruits, peel and wash them, accurately weigh 100 g, add 900 g of purified water and blend (Midea MJ-BL80Y21 high-speed blender, three speeds, 20 s / min, 10 min) to obtain bitter acorn slurry; filter the bitter acorn slurry through 8 layers of gauze (model 21s×32s) to obtain bitter acorn slurry filtrate; sterilize the bitter acorn slurry filtrate at 80℃ for 30 min, cool to room temperature, and then inoculate kombucha (Changsha Hepu Biotechnology Co., Ltd., liquid) into the sterilized and cooled bitter acorn slurry filtrate at an inoculation amount of 3v / v% (volume of kombucha / volume of sterilized and cooled bitter acorn slurry filtrate × 100%), and incubate at 37℃ for 36 h to obtain bitter acorn fermentation broth.

[0087] (b) Flavoring: Add 90 g of isomaltooligosaccharide (Zhejiang Nuoyi Biotechnology Co., Ltd.) to 500 g of bitter oak fermentation liquid, stir evenly to adjust the sweetness and sourness, and obtain the flavored bitter oak fermentation liquid.

[0088] (c) Color adjustment: Select fresh purple sweet potatoes, peel and wash them, accurately weigh 600 g, add 400 g of purified water and blend (Midea MJ-BL80Y21 high-speed blender, three speeds, 20 s / min, 10 min) to obtain purple sweet potato pulp; filter the purple sweet potato pulp through 8 layers of gauze (model 21s×32s) to obtain purple sweet potato pulp filtrate; centrifuge the purple sweet potato pulp filtrate at 8000 rpm for 10 min, collect the supernatant to obtain purple sweet potato anthocyanin aqueous extract; add 80 g of purple sweet potato anthocyanin aqueous extract to 590 g of flavored bitter oak fermentation liquid, stir evenly to adjust the color, and obtain flavored and flavored bitter oak fermentation liquid.

[0089] (d) Preparation of composite coagulant: Accurately weigh 10 g of fig seeds (fresh or dried, dried in this example), add 170 g of purified water, gently rub by hand (about 20 times per minute, rubbing for about 5 minutes), then filter through 8 layers of gauze (model 21s×32s) to obtain filtrate, which is fig seed pectin solution. Then add 20 g of konjac powder (about 80 mesh) and 0.4 g of wild lotus root powder (about 80 mesh) to the fig seed pectin solution, mix well and obtain composite coagulant.

[0090] (e) Jelly Formation: 60 g, 100 g, 140 g, 180 g, and 220 g of the composite coagulant were mixed evenly with 270 g, 230 g, 190 g, 150 g, and 110 g of purified water and 670 g of coloring and flavoring acorn fermentation liquid, respectively. The mixtures were then solidified at 4°C for 30 min to produce prebiotic-rich kombucha-fermented acorn jelly. The effect of the amount of composite coagulant added on the sensory properties of the jelly was investigated. Results are shown below. Figure 4 .

[0091] from Figure 4 As can be seen, the amount of compound coagulant added has a significant impact on the sensory score of the jelly. When the amount of compound coagulant added is insufficient, the jelly has a poor gel state, uneven solidification, and poor elasticity; when the amount added is higher than 14wt%, the bitter oak jelly becomes hard, loses elasticity, and the sensory score drops significantly. Therefore, 14wt% is selected as the optimal amount of compound coagulant added, at which point the jelly has better sensory properties.

[0092] (5.2) Determination of the raw material ratio of composite coagulant

[0093] Based on the above results, the composition of the composite coagulant was determined by adjusting the proportions of the three composite coagulant raw materials.

[0094] A. Composition

[0095] Based on 100 parts by weight, the contents consist of 50 parts by weight of bitter oak fermentation broth, 9 parts by weight of isomaltooligosaccharide, 8 parts by weight of purple sweet potato anthocyanin aqueous extract, 14 parts by weight of composite coagulant, and the remainder is purified water.

[0096] B. Preparation method

[0097] (a) Preparation of bitter acorn fermentation broth: Select fresh bitter acorn fruits, peel and wash them, accurately weigh 100 g, add 900 g of purified water and blend (Midea MJ-BL80Y21 high-speed blender, three speeds, 20 s / min, 10 min) to obtain bitter acorn slurry; filter the bitter acorn slurry through 8 layers of gauze (model 21s×32s) to obtain bitter acorn slurry filtrate; sterilize the bitter acorn slurry filtrate at 80℃ for 30 min, cool to room temperature, and then inoculate kombucha (Changsha Hepu Biotechnology Co., Ltd., liquid) into the sterilized and cooled bitter acorn slurry filtrate at an inoculation amount of 3v / v% (volume of kombucha / volume of sterilized and cooled bitter acorn slurry filtrate × 100%), and incubate at 37℃ for 36 h to obtain bitter acorn fermentation broth.

[0098] (b) Flavoring: Add 90 g of isomaltooligosaccharide (Zhejiang Nuoyi Biotechnology Co., Ltd.) to 500 g of bitter oak fermentation liquid, stir evenly to adjust the sweetness and sourness, and obtain the flavored bitter oak fermentation liquid.

[0099] (c) Color adjustment: Select fresh purple sweet potatoes, peel and wash them, accurately weigh 600 g, add 400 g of purified water and blend (Midea MJ-BL80Y21 high-speed blender, three speeds, 20 s / min, 10 min) to obtain purple sweet potato pulp; filter the purple sweet potato pulp through 8 layers of gauze (model 21s×32s) to obtain purple sweet potato pulp filtrate; centrifuge the purple sweet potato pulp filtrate at 8000 rpm for 10 min, collect the supernatant to obtain purple sweet potato anthocyanin aqueous extract, add 80 g of purple sweet potato anthocyanin aqueous extract to 590 g of flavored bitter oak fermentation liquid, stir evenly to adjust the color, and obtain flavored and flavored bitter oak fermentation liquid.

[0100] (d) Preparation of composite coagulant:

[0101] Option 1: The ratio of fig seed: konjac powder: wild lotus root powder is 4:7:0.25: Accurately weigh 8 g of fig seeds (fresh or dried, dried in this example), add 170 g of purified water, gently knead by hand (kneading about 20 times per minute, kneading for about 5 minutes), then filter through 8 layers of gauze (size 21s×32s) to obtain the filtrate, which is the fig seed pectin solution. Then add 14 g of konjac powder (about 80 mesh) and 0.5 g of wild lotus root powder (about 80 mesh) to the fig seed pectin solution, mix well and obtain the composite coagulant.

[0102] Option 2: The ratio of fig seed: konjac powder: wild lotus root powder is 5:10:0.2: Accurately weigh 10 g of fig seeds (fresh or dried, dried in this example), add 170 g of purified water, and gently knead by hand (kneading about 20 times per minute for about 5 minutes). Then filter through 8 layers of gauze (size 21s×32s) to obtain the filtrate, which is the fig seed pectin solution. Then add 20 g of konjac powder (about 80 mesh) and 0.4 g of wild lotus root powder (about 80 mesh) to the fig seed pectin solution, mix well and obtain the composite coagulant.

[0103] Option 3: The ratio of fig seed: konjac powder: wild lotus root powder is 3:8:0.15: Accurately weigh 6 g of fig seeds (fresh or dried, dried in this example), add 170 g of purified water, and gently knead by hand (kneading about 20 times per minute for about 5 minutes). Then filter through 8 layers of gauze (model 21s×32s) to obtain the filtrate, which is the fig seed pectin solution. Then add 16 g of konjac powder (about 80 mesh) and 0.3 g of wild lotus root powder (about 80 mesh) to the fig seed pectin solution, mix well and obtain the composite coagulant.

[0104] (e) Jelly forming: 140 g each of the three compound coagulants were mixed evenly with 190 g of purified water and 670 g of coloring and flavoring strychnine fermentation liquid, and solidified at 4°C for 30 min to produce kombucha-fermented strychnine jelly rich in prebiotics. The effect of the ratio of compound coagulant raw materials on the sensory properties of the jelly was investigated.

[0105] The results are shown in Table 2.

[0106] Table 2 Determination of the raw material ratio of composite coagulant

[0107]

[0108] (6) Orthogonal optimization of preparation conditions for kombucha-fermented sago jelly rich in prebiotics

[0109] Using the fermentation broth of Castanopsis fargesii, isomaltooligosaccharide, anthocyanin aqueous extract of purple sweet potato, and the amount of compound coagulant added as experimental factors, represented by the letters A, B, C, and D respectively, an L9(3) coagulant design was developed. 4 The orthogonal experimental table (Table 3) was used, with the sensory score of the jelly as the indicator. The addition amounts of bitter oak fermentation liquid, isomaltooligosaccharide, purple sweet potato anthocyanin aqueous extract and composite coagulant are shown in 3. Other preparations are referred to (5.2). Among them, the mass ratio of fig seed: konjac powder: wild lotus root powder is 5:10:0.2.

[0110] Table 3. Orthogonal Factor Level Table

[0111]

[0112] The results are shown in Table 4. Table 4 shows that, based on sensory evaluation, the order of influencing factors is C > D > B > A, i.e., purple sweet potato anthocyanin aqueous extract content > composite coagulant content > isomaltooligosaccharide content > cassia fermentation broth content. Range analysis indicates that the optimal scheme is A3B3C2D2, i.e., cassia fermentation broth 55wt%, isomaltooligosaccharide 12wt%, purple sweet potato anthocyanin aqueous extract 8wt%, and composite coagulant 14wt%.

[0113] Table 4 L9 (3) 4 Sensory scoring results of orthogonal experiments

[0114]

[0115] In Table 4, K1, K2, and K3 represent the total level, k1, k2, and k3 represent the average level, and R represents the range.

[0116] Example 2: Preparation of prebiotic-rich kombucha-fermented oak jelly (the optimal technical solution screened by orthogonal experiment in Example 1)

[0117] A. Composition

[0118] Based on 100 parts by weight, the contents consist of 55 parts by weight of bitter oak fermentation broth, 12 parts by weight of isomaltooligosaccharide, 8 parts by weight of purple sweet potato anthocyanin aqueous extract, 14 parts by weight of composite coagulant, and the remainder is purified water.

[0119] B. Preparation method

[0120] (a) Preparation of bitter acorn fermentation broth: Select fresh bitter acorn fruits, peel and wash them, accurately weigh 100 g, add 900 g of purified water and blend (Midea MJ-BL80Y21 high-speed blender, three speeds, 20 s / min, 10 min) to obtain bitter acorn slurry; filter the bitter acorn slurry through 8 layers of gauze (model 21s×32s) to obtain bitter acorn slurry filtrate; sterilize the bitter acorn slurry filtrate at 80℃ for 30 min, cool to room temperature, and then inoculate kombucha (Changsha Hepu Biotechnology Co., Ltd., liquid) into the sterilized and cooled bitter acorn slurry filtrate at an inoculation amount of 3v / v% (volume of kombucha / volume of sterilized and cooled bitter acorn slurry filtrate × 100%), and incubate at 37℃ for 36 h to obtain bitter acorn fermentation broth.

[0121] (b) Flavoring: Add 120 g of isomaltooligosaccharide (Zhejiang Nuoyi Biotechnology Co., Ltd.) to 550 g of bitter oak fermentation liquid, stir evenly to adjust the sweetness and sourness, and obtain the flavored bitter oak fermentation liquid.

[0122] (c) Color adjustment: Select fresh purple sweet potatoes, peel and wash them, accurately weigh 600 g, add 400 g of purified water and blend (Midea MJ-BL80Y21 high-speed blender, three speeds, 20 s / min, 10 min) to obtain purple sweet potato pulp; filter the purple sweet potato pulp through 8 layers of gauze (model 21s×32s) to obtain purple sweet potato pulp filtrate; centrifuge the purple sweet potato pulp filtrate at 8000 rpm for 10 min, collect the supernatant to obtain purple sweet potato anthocyanin aqueous extract; add 80 g of purple sweet potato anthocyanin aqueous extract to 670 g of flavored bitter oak fermentation liquid, stir evenly to adjust the color, and obtain flavored and flavored bitter oak fermentation liquid.

[0123] (d) Preparation of composite coagulant: Accurately weigh 10 g of fig seeds (fresh or dried, dried in this example), add 170 g of purified water, gently rub by hand (about 20 times per minute, rubbing for about 5 minutes), then filter through 8 layers of gauze (model 21s×32s) to obtain filtrate, which is fig seed pectin solution. Then add 20 g of konjac powder (about 80 mesh) and 0.4 g of wild lotus root powder (about 80 mesh) to the fig seed pectin solution, mix well and obtain composite coagulant.

[0124] (e) Jelly Formation: 140 g of compound coagulant, 110 g of purified water, and 750 g of coloring and flavoring acorn fermentation liquid were mixed evenly and solidified at 4°C for 30 min to produce a prebiotic-rich kombucha-fermented acorn jelly. The jelly prepared in this example received a sensory score of 82.3. Figure 5 As shown, the jelly prepared in this embodiment has a smooth, glossy, and undamaged appearance, a delicate and chewy texture, a balanced sweet and sour taste, a unique flavor, and excellent sensory quality.

[0125] Comparative Example 1: Preparation of Castanopsis jelly without kombucha fermentation

[0126] A. Composition

[0127] Based on 100 parts by weight, the filtrate of bitter oak pulp consists of 55 parts by weight, isomaltooligosaccharide 12 parts by weight, purple sweet potato anthocyanin aqueous extract 8 parts by weight, composite coagulant 14 parts by weight, and the remainder is purified water.

[0128] B. Preparation method

[0129] (a) Preparation of bitter acorn pulp filtrate: Select fresh bitter acorn fruits, peel and wash them, accurately weigh 100 g, add 900 g of purified water and blend (Midea MJ-BL80Y21 high-speed blender, three speeds, 20 s / min, 10 min) to obtain bitter acorn pulp; filter the bitter acorn pulp with 8 layers of gauze (model 21s×32s) to obtain bitter acorn pulp filtrate.

[0130] (b) Flavoring: Add 120 g of isomaltooligosaccharide (Zhejiang Nuoyi Biotechnology Co., Ltd.) to 550 g of bitter oak pulp filtrate, stir evenly to adjust the sweetness and acidity, and obtain the flavored bitter oak pulp filtrate.

[0131] (c) Color adjustment: Select fresh purple sweet potatoes, peel and wash them, accurately weigh 600 g, add 400 g of purified water and blend (Midea MJ-BL80Y21 high-speed blender, three speeds, 20 s / min, 10 min) to obtain purple sweet potato pulp; filter the purple sweet potato pulp through 8 layers of gauze (model 21s×32s) to obtain purple sweet potato pulp filtrate; centrifuge the purple sweet potato pulp filtrate at 8000 rpm for 10 min, collect the supernatant to obtain purple sweet potato anthocyanin aqueous extract, add 80 g of purple sweet potato anthocyanin aqueous extract to 670 g of flavored bitter oak pulp filtrate, stir evenly to adjust the color, and obtain flavored and flavored bitter oak pulp filtrate.

[0132] (d) Preparation of composite coagulant: Accurately weigh 10 g of fig seeds (fresh or dried, dried in this example), add 170 g of purified water, gently rub by hand (about 20 times per minute, rubbing for about 5 minutes), then filter through 8 layers of gauze (model 21s×32s) to obtain filtrate, which is fig seed pectin solution. Then add 20 g of konjac powder (about 80 mesh) and 0.4 g of wild lotus root powder (about 80 mesh) to the fig seed pectin solution, mix well and obtain composite coagulant.

[0133] (e) Jelly forming: Mix 140 g of compound coagulant, 110 g of purified water and 750 g of styrax slurry filtrate for coloring and flavoring evenly, and solidify at 4°C for 30 min to make styrax jelly.

[0134] Comparative Example 2: Preparation of Kombucha Fermented Castanopsis Jelly without Purple Sweet Potato Anthocyanins

[0135] A. Composition

[0136] Based on 100 parts by weight, the contents consist of 55 parts by weight of bitter oak fermentation broth, 12 parts by weight of isomaltooligosaccharide, 14 parts by weight of composite coagulant, and the remainder is purified water.

[0137] B. Preparation method

[0138] (a) Preparation of bitter acorn fermentation broth: Select fresh bitter acorn fruits, peel and wash them, accurately weigh 100 g, add 900 g of purified water and blend (Midea MJ-BL80Y21 high-speed blender, three speeds, 20 s / min, 10 min) to obtain bitter acorn slurry; filter the bitter acorn slurry through 8 layers of gauze (model 21s×32s) to obtain bitter acorn slurry filtrate; sterilize the bitter acorn slurry filtrate at 80℃ for 30 min, cool to room temperature, and then inoculate kombucha (Changsha Hepu Biotechnology Co., Ltd., liquid) into the sterilized and cooled bitter acorn slurry filtrate at an inoculation amount of 3v / v% (volume of kombucha / volume of sterilized and cooled bitter acorn slurry filtrate × 100%), and incubate at 37℃ for 36 h to obtain bitter acorn fermentation broth.

[0139] (b) Flavoring: Add 120 g of isomaltooligosaccharide (Zhejiang Nuoyi Biotechnology Co., Ltd.) to 550 g of bitter oak fermentation liquid, stir evenly to adjust the sweetness and sourness, and obtain the flavored bitter oak fermentation liquid.

[0140] (c) Preparation of composite coagulant: Accurately weigh 10 g of fig seeds (fresh or dried, dried in this example), add 170 g of purified water, gently rub by hand (about 20 times per minute, rubbing for about 5 minutes), and then filter through 8 layers of gauze (model 21s×32s) to obtain filtrate, which is fig seed pectin solution. Then add 20 g of konjac powder (about 80 mesh) and 0.4 g of wild lotus root powder (about 80 mesh) to the fig seed pectin solution, mix well and obtain composite coagulant.

[0141] (d) Jelly forming: Mix 140 g of compound coagulant, 190 g of purified water and 670 g of coloring and flavoring bitter oak fermentation liquid evenly, and solidify at 4℃ for 30 min to make kombucha fermented bitter oak jelly without purple sweet potato anthocyanin addition.

[0142] Comparative Example 3: Preparation of jelly without Castanopsis sclerophylla, kombucha fermentation, and purple sweet potato anthocyanin addition

[0143] A. Raw material composition

[0144] Based on 100 parts by weight, the product contains 12 parts by weight of isomaltooligosaccharide, 14 parts by weight of composite coagulant, and the remainder is purified water.

[0145] B. Preparation method

[0146] (a) Preparation of composite coagulant: Accurately weigh 10 g of fig seeds (fresh or dried, dried in this example), add 170 g of purified water, gently rub by hand (about 20 times per minute, rubbing for about 5 minutes), and then filter through 8 layers of gauze (size 21s×32s) to obtain filtrate, which is fig seed pectin solution. Then add 20 g of konjac powder (about 80 mesh) and 0.4 g of wild lotus root powder (about 80 mesh) to the fig seed pectin solution, mix well and obtain composite coagulant.

[0147] (b) Jelly forming: Mix 120 g of isomaltooligosaccharide, 140 g of composite coagulant and 740 g of purified water evenly, and solidify at 4°C for 30 min to make jelly.

[0148] Experimental Example 1

[0149] Determination of total phenol content in jelly

[0150] The total phenol content in jelly samples was analyzed using the Folin-Ciocalteu method. The jelly samples included those prepared in Example 2, Comparative Examples 1, 2, and 3, as well as a commercially available lactic acid bacteria jelly (Xu Fu Chi, yogurt flavor). The principle of this method is to convert polyphenols into colored complexes with a characteristic absorption peak at 760 nm through a redox reaction. Gallic acid was used as a standard. 5 mg of gallic acid was weighed and dissolved in purified water to prepare a 1 mg / mL standard solution, which was then serially diluted with purified water to 20, 40, 60, 80, 100, 120, 160, and 200 μg / mL. 2 g of the pulped jelly sample was weighed, and 8 mL of anhydrous ethanol was added. The mixture was extracted by ultrasonication at 400 W for 30 min, centrifuged at 8000 rpm for 10 min, and the supernatant was collected. Take 100 μL of supernatant and diluted gallic acid standard solution, add 1.15 mL of purified water and 250 μL of Folin-Ciocalteu reagent (Sinopharm Chemical Reagent Co., Ltd., BR grade), respectively, shake well, and react at room temperature for 1 min. Then add 1 mL of 7.5 wt% Na₂CO₃ solution, shake well, and react in the dark at room temperature for 2 h. Pipette 200 μL into a 96-well plate and measure the absorbance at 760 nm using a microplate reader. Plot the gallic acid standard curve, and the regression equation is y = 0.0023x - 0.0004 (R²). 2 =0.9995), the total phenol content of each jelly sample was calculated based on the gallic acid standard curve, and the total phenol content was expressed as gallic acid equivalent (GAE mg / g). The test results of the jelly samples are as follows. Figure 6 As shown. From Figure 6As can be seen, the jelly prepared in Example 2 of this invention contains significantly higher levels of polyphenols than the jelly prepared in Comparative Examples 1-3 and commercially available ordinary jelly. This is mainly due to the abundant polyphenols in the fermented sago palm broth and the anthocyanin aqueous extract of purple sweet potato. Numerous studies have shown that natural polyphenols have significant antioxidant activity and intestinal homeostasis regulation effects, which are very beneficial to human health and align with consumers' pursuit of green and healthy foods.

[0151] Experimental Example 2

[0152] Determination of antioxidant activity of jelly

[0153] The antioxidant activity of the jelly was determined using the ABTS•+ free radical scavenging capacity. The jelly sample was the same as in Example 1. ABTS•+ has maximum absorption at 734 nm and appears blue-green. When it is scavenged, the solution color lightens, resulting in a decrease in absorbance. 200 μL of the supernatant from Example 1 was pipetted into a 1.5 mL centrifuge tube, and 800 μL of ABTS•+ solution (Sinopharm Chemical Reagent Co., Ltd.) was added and mixed. The mixture was incubated at room temperature for 6 min. 200 μL was then pipetted into a 96-well plate, and the absorbance (A1) was measured at 734 nm using a microplate reader. The blank control group was replaced with 80 v / v% ethanol solution, and the absorbance (A2) was measured. The ABTS•+ free radical scavenging rate was calculated using the following formula: ABTS•+ free radical scavenging rate R (%) = (A2 - A1) / A2 × 100%. The results are as follows: Figure 7 As shown. From Figure 7 As can be seen from the results, compared with other jelly samples, the jelly prepared in Example 2 of this invention exhibited the strongest ABTS•+ free radical scavenging ability. This indicates that the addition of Castanopsis sclerotium fermentation broth and purple sweet potato anthocyanin aqueous extract significantly increased the antioxidant activity of the jelly product, which is mainly related to its rich polyphenol content. Simultaneously, the organic acids produced by kombucha fermentation, as well as some trace amounts of bacterial enzymes, also possess certain antioxidant activity.

Claims

1. A kombucha-fermented oak jelly rich in prebiotics, characterized in that, Based on 100 parts by weight, it includes: 55 parts by weight of bitter oak fermentation broth, 12 parts by weight of isomaltooligosaccharide, 8 parts by weight of purple sweet potato anthocyanin aqueous extract, 14 parts by weight of composite coagulant, and the remainder is water. The oak fermentation broth is prepared by the following steps: (1) Preparation of bitter acorn pulp filtrate: After peeling and washing fresh bitter acorn fruits, mix them with water and pulp to obtain bitter acorn pulp; filter the bitter acorn pulp with multiple layers of gauze to obtain bitter acorn pulp filtrate; wherein, the mass ratio of peeled and washed bitter acorn fruits to water is 1:5-1:

25. (2) Sterilization of bitter oak pulp filtrate: Sterilize the bitter oak pulp filtrate and cool it; (3) Fermentation of bitter oak pulp filtrate: Kombucha is inoculated into sterilized and cooled bitter oak pulp filtrate and fermented to obtain bitter oak fermentation liquid; wherein, the kombucha is inoculated into sterilized and cooled bitter oak pulp filtrate at an inoculation rate of 1v / v%-4v / v%, and the fermentation conditions are: standing, fermentation temperature of 30℃-38℃, and fermentation time of 12 h-72 h; The purple sweet potato anthocyanin aqueous extract was prepared by the following steps: (1) Preparation of purple sweet potato pulp: Fresh purple sweet potatoes are peeled, washed, and mixed with water to make pulp; the purple sweet potato pulp is filtered through multiple layers of gauze to obtain purple sweet potato pulp filtrate; wherein, the mass ratio of peeled and washed purple sweet potatoes to water is 1:0.25-1.5; (2) Centrifugation: Centrifuge the purple sweet potato pulp filtrate, collect the supernatant, and prepare purple sweet potato anthocyanin aqueous extract; The composite coagulant is prepared by the following steps: (1) Preparation of fig seed pectin solution: Fresh or dried fig seeds are mixed with water, gently rubbed, and filtered through multiple layers of gauze to obtain filtrate, which is fig seed pectin solution; wherein, fig seeds and water are mixed at a mass ratio of 1:10-1:20, and the mass of fig seeds is based on the mass of dried fig seeds; (2) Preparation of composite coagulant: Konjac powder and wild lotus root powder were added to the pectin solution of fig seeds and mixed well to obtain composite coagulant; wherein, the mass ratio of fig seeds, konjac powder and wild lotus root powder was 5:10:0.2, and the mass of fig seeds was based on the mass of dried fig seeds.

2. The kombucha-fermented oak jelly rich in prebiotics according to claim 1, characterized in that, In step (2) of preparing the fermentation broth of Castanopsis sclerophylla, sterilize at 80-110℃ for 10-30 min and cool to room temperature.

3. The kombucha-fermented oak jelly rich in prebiotics according to claim 1, characterized in that, In step (2) of preparing purple sweet potato anthocyanin aqueous extract, the centrifugation speed is 5000-8000 rpm and the centrifugation time is 10-20 min.

4. The kombucha-fermented oak jelly rich in prebiotics according to claim 1, characterized in that, In step (1) of preparing the composite coagulant, gently knead by hand, kneading 20-40 times per minute for 3-15 minutes.

5. A method for preparing a prebiotic-rich kombucha-fermented oak jelly according to any one of claims 1-4, characterized in that, Includes the following steps: (1) Preparation of bitter oak fermentation liquid: Peel and wash fresh bitter oak fruit, add water to make pulp, filter, sterilize and cool, and then inoculate with kombucha to ferment and obtain bitter oak fermentation liquid; (2) Flavoring: Add isomaltooligosaccharide to the bitter oak fermentation liquid to adjust the sweetness and acidity of the bitter oak fermentation liquid, and obtain the flavored bitter oak fermentation liquid; (3) Color adjustment: Peel and wash fresh purple sweet potatoes, add water to make pulp, filter, centrifuge, collect the supernatant to obtain purple sweet potato anthocyanin aqueous extract; add purple sweet potato anthocyanin aqueous extract to flavored bitter oak fermentation liquid to adjust the color, and obtain flavored and flavored bitter oak fermentation liquid. (4) Preparation of composite coagulant: Fresh or dried fig seeds are rubbed with water and filtered to obtain the filtrate, which is the fig seed pectin solution. Konjac powder and wild lotus root powder are added to the fig seed pectin solution and mixed well to obtain the composite coagulant. (5) Solidification and shaping: Mix the composite coagulant, water and the flavored and colored sago fermentation liquid evenly, and solidify at low temperature to obtain the kombucha fermented sago jelly rich in prebiotics.

6. The method for preparing a prebiotic-rich kombucha-fermented oak jelly according to claim 5, characterized in that, In step (5), the low-temperature solidification conditions are: standing, solidification temperature of 2-15℃, and solidification time of 20-60 min.

Images