Fermented siraitia grosvenorii concentrated juice and preparation method thereof

Abstract

The invention relates to a fermented siraitia grosvenorii concentrated juice which meets the following conditions: the content of mogroside V is 0.1-10 wt%, the pH value range is 4.5-6.5, the ethanol content is less than 0.5 wt%, and the total acid content is more than 2 wt%. The fermented siraitia grosvenorii concentrated juice is a byproduct in the production process of a siraitia grosvenorii extract, and is obtained by sequentially performing high-temperature gelatinization, enzymolysis, lactobacillus fermentation, saccharomycetes fermentation, centrifugation, filtration, desalination and decoloration and concentration. The by-product is a mixture of upper column effluent of a macroporous adsorption resin column, horizontal screw centrifugal slag and disc centrifugal heavy liquid. According to the method, horizontal spiral centrifugal residues and disc type centrifugal heavy liquid which are difficult to utilize in the prior art are mixed with column effluent liquid on a macroporous adsorption resin column according to specific mass, then the mixture is prepared through a specific technology, and the obtained fermented siraitia grosvenorii concentrated juice product is light yellow transparent liquid, has fermented fruit fragrance, tastes sour and sweet and is rich in lactic acid and vitamin B.

Description

Technical Field

[0001] This invention relates to a concentrated monk fruit juice and its preparation method, specifically to a fermented monk fruit concentrated juice and its preparation method. Background Technology

[0002] Monk fruit (Siraitia grosvenorii), the fruit of a perennial vine belonging to the Cucurbitaceae family, is produced in the mountainous areas of Guilin in Guangxi, Shaoyang, Huaihua, Yongzhou in Hunan, and southeastern Guizhou. It is a precious local specialty of my country and one of the first batch of materials approved by the state for both medicinal and edible uses. Monk fruit is highly nutritious, containing abundant vitamin C, as well as mogrosides, fructose, glucose, protein, pectin, cellulose, and lipids. According to the *Chinese Materia Medica*, monk fruit is sweet and cool in nature, entering the lung and large intestine meridians. It has the effects of moistening the lungs and relieving cough, promoting body fluid production and quenching thirst, and is suitable for coughs due to lung heat or dryness, whooping cough, and thirst due to summer heat. The *Lingnan Herbal Collection* also records that monk fruit is cool in nature, sweet in taste, and enters the lung and large intestine meridians, having the effects of clearing the lungs and relieving sore throat, resolving phlegm and relieving cough, and moistening the intestines and promoting bowel movements. It is mainly used to treat cough, asthma, sore throat, constipation, and other ailments. Modern medical research has confirmed that mogrosides, found in monk fruit, are a natural sweetener 400 times sweeter than sucrose, but they produce no calories, making them a suitable sweetener for diabetics, obese individuals, and others who should limit their sugar intake. Mogrosides are safe and non-toxic as a food ingredient; the national mandatory standard GB2760, "Standard for the Use of Food Additives," stipulates that mogrosides can be used without limit in various foods. Due to its numerous excellent properties, mogrosides can completely or partially replace sucrose, thus finding widespread application in the food industry. Furthermore, mogrosides also have very broad application prospects and market potential in the pharmaceutical, cosmetic, and health food fields.

[0003] The industrial production of monk fruit extract has been implemented for many years, and industry practitioners have conducted in-depth research on monk fruit extract. However, the focus is generally on mogrosides, and there is relatively little research on the natural components of monk fruit other than mogrosides.

[0004] CN118702196A discloses a process for preparing a concentrated solution after extracting mogrosides, as well as the concentrated solution and its application. The process uses the chromatography liquid discharged from the adsorption resin column (i.e., the effluent from the macroporous adsorption resin column) of the mogroside aqueous solution as raw material, and obtains the concentrated solution through vacuum decompression concentration, sterilization, cooling and other steps.

[0005] CN116510351A discloses a method for separating mogrosides and other components, wherein the treatment of the column effluent from the macroporous adsorption resin column includes steps such as pH adjustment, secondary adsorption, acid washing, water washing, ethanol elution, and concentration to obtain mogroside pigments, polyphenols, and flavonoids.

[0006] CN110776580A discloses a method for recovering high-content acidic polysaccharides from the effluent from the column of monk fruit. The method uses the effluent from the column of monk fruit (i.e., the effluent from the macroporous adsorption resin column) as raw material and proceeds through steps such as concentration, alcohol precipitation, separation, washing, resolution, column separation, filtration, and drying to obtain monk fruit acidic polysaccharides.

[0007] CN114410411A discloses a monk fruit wine and its preparation method, which uses the effluent from a monk fruit water extract loaded onto a macroporous adsorption resin as raw material, and obtains monk fruit wine through steps such as concentration, Maillard reaction, enzymatic hydrolysis, nanofiltration, and fermentation.

[0008] CN116098249A discloses a method for preparing pure monk fruit juice with multiple sweeteners. The method uses by-products of monk fruit production (such as effluent from macroporous adsorption resin) as raw materials and proceeds through steps such as hydrolysis, glucose isomerization, microfiltration clarification, decolorization and impurity removal, blending, concentration, and sterilization to obtain monk fruit juice.

[0009] CN106923113A discloses a process for producing concentrated monk fruit juice from waste liquid discharged from a mogroside adsorption resin column. The process uses the waste liquid fed into the adsorption resin during the production of fresh monk fruit (i.e., the effluent from the macroporous adsorption resin column) as raw material, and proceeds through steps such as ceramic membrane filtration, pH adjustment with anion exchange resin, reverse osmosis membrane concentration, decolorization with decolorizing resin, activated carbon decolorization, plate and frame filtration, titanium rod fine filtration, reverse osmosis membrane concentration, low temperature cooling, ceramic membrane filtration, vacuum concentration, and sterilization to obtain concentrated monk fruit juice.

[0010] CN112244185A discloses a method for preparing a concentrated monk fruit juice with a sugar-rich flavor. The method uses the waste liquid generated during the preparation of monk fruit glycosides (i.e., the effluent from the macroporous adsorption resin column) as raw material, and obtains the concentrated monk fruit juice through steps such as membrane filtration, vacuum concentration, alcohol precipitation, decolorization, impurity removal, pH adjustment, ultrafiltration, and vacuum concentration.

[0011] CN113854533A discloses a method for preparing mogrosides, mogrophenolic acids, and concentrated mogroside juice from fresh mogroside. The description of "preparing concentrated mogroside juice (syrup) from adsorption resin effluent" involves using the effluent from a macroporous adsorption resin column as raw material, followed by desalting with cation exchange resin, removing pesticide residues with anion exchange resin, extracting with edible vegetable oil, removing plasticizers with membrane separation, stepwise clarification, and concentration to obtain a concentrated solution.

[0012] Existing technologies for processing monk fruit concentrate share a common feature: they only treat the effluent from the monk fruit macroporous adsorption resin column, without comprehensively treating other monk fruit byproducts.

[0013] In recent years, the scale of the domestic monk fruit deep processing industry has grown rapidly, with the output and value of monk fruit extracts repeatedly reaching new highs. However, this has also resulted in a considerable quantity and variety of monk fruit processing byproducts. How to rationally handle these byproducts and achieve comprehensive utilization of monk fruit resources, rather than simply and crudely treating them as industrial waste, has become a reality that those involved in the monk fruit deep processing industry must confront.

[0014] Therefore, there is an urgent need for a novel fermented monk fruit concentrate that can comprehensively utilize various byproducts generated during the production and processing of monk fruit, and is suitable for industrial-scale mass production, as well as its preparation method. Summary of the Invention

[0015] To overcome the shortcomings of existing technologies in the comprehensive utilization of by-products from monk fruit production, such as serious waste, high cost, limited application, and low added value, this invention proposes a fermented monk fruit concentrate and its preparation method. Specifically, this invention provides the following technical solutions to achieve the above objectives:

[0016] A fermented monk fruit concentrate that meets the following conditions: the content of mogroside V is 0.1-10wt%, the pH value range is 4.5-6.5, the ethanol content is <0.5wt%, and the total acid content is ≥1wt%.

[0017] Ethanol, vitamin B, and lactic acid are all produced during fermentation. Compared with traditional decolorized monk fruit concentrate, the fermented monk fruit concentrate of this invention has a unique fermented fruit aroma and a sweet and sour taste.

[0018] Furthermore, the fermented monk fruit concentrate has a monk fruit glycoside V content of 0.3-1.5%, a pH value range of 5.0-6.0, an ethanol content of 0.1-0.4 wt%, and a total acid content of ≥2%, but not exceeding 5 wt%, preferably not exceeding 4 wt%, and more preferably not exceeding 3 wt%.

[0019] Furthermore, the fermented monk fruit concentrate is a byproduct of the monk fruit extract production process, which is obtained by sequentially undergoing high-temperature gelatinization, enzymatic hydrolysis, lactic acid bacteria fermentation, yeast fermentation, centrifugation, filtration, desalting and decolorization, and concentration.

[0020] Furthermore, the byproduct is a mixture of column effluent from macroporous adsorption resin, decanter centrifuge residue, and disc centrifuge heavy liquid in a mass ratio of 1:0.01~0.15:0.01~0.15; preferably, the mass ratio of column effluent from macroporous adsorption resin, decanter centrifuge residue, and disc centrifuge heavy liquid is 1:0.05~0.1:0.05~0.1.

[0021] During the extraction of mogrosides, a large amount of pectin, crude fiber, protein, and other substances are suspended in the extract. These suspended substances can be removed by horizontal screw centrifugation, yielding mogroside centrifugation residue. This residue is a semi-solid, meat-like material (70-80% moisture content) continuously discharged from the horizontal screw centrifuge after the hot water extract of mogroside has been processed. Disc centrifugation heavy liquid is a thick, rice-water-like residue (85-95% moisture content) periodically discharged from the disc centrifuge during material processing (receiving the centrifugal liquid from the horizontal screw centrifuge).

[0022] The inventors discovered that by gelatinizing, enzymatically hydrolyzing, and fermenting a mixture of column effluent from a macroporous adsorption resin column, decanter centrifuge residue, and dish centrifuge heavy liquid in a specific ratio, a concentrated fermented monk fruit juice can be obtained. Before treatment, the decanter centrifuge residue (semi-solid) had a very poor taste and a strong astringent flavor; the dish centrifuge heavy liquid (emulsion) was turbid and contained excessive insoluble matter. After treatment using the method of this invention, the decanter centrifuge residue and dish centrifuge heavy liquid, which were originally considered waste, were partially transformed into soluble, digestible small-molecule components through enzymatic hydrolysis; and partially transformed into beneficial enzyme-like components through fermentation.

[0023] The main byproduct of monk fruit extract production is the column effluent from macroporous adsorption resin, whose main components are water, glucose, fructose, and small amounts of inorganic salts and pigments. Currently, most publicly disclosed patents related to monk fruit concentrate in the industry use this as a raw material to "turn waste into treasure." This invention application also uses the column effluent from macroporous adsorption resin as one of the raw materials, aiming not only to recover the abundant small-molecule sugars in this byproduct but also to utilize these small-molecule sugars as substrates for lactic acid bacteria and yeast fermentation. However, there is no mature utilization technology for the other two byproducts in monk fruit extract production: decanter centrifuge residue and dish centrifuge heavy liquid. Their main components, besides water, include abundant protein, pectin, and crude fiber. Due to the poor water solubility of these components and the lack of scientific comprehensive utilization technology, in the current industry production process, decanter centrifuge residue and dish centrifuge heavy liquid are generally treated as waste (even if they can be processed into feed additives, the processing cost is high and the disposal capacity is small, making it economically unfeasible). This not only increases the burden of environmental treatment but also wastes natural resources. This invention application uses both horizontal screw centrifuge residue and disc centrifuge heavy liquid, which are currently difficult to process in large quantities in the monk fruit industry, as the main raw materials. The aim is to provide a method suitable for industrial-scale batch processing, addressing industry pain points and offering a reference for the industry. However, it is necessary to reasonably control the ratio of the three raw materials and, for example, the fermentation order; otherwise, a fermented monk fruit concentrate with excellent taste and flavor cannot be obtained.

[0024] The present invention also provides a method for preparing the above-mentioned fermented monk fruit concentrate, comprising the following steps:

[0025] (1) High-temperature gelatinization: Mix various by-products in the production process of monk fruit extract according to the proportion, stir evenly, and heat, keep warm, and cool down to obtain gelatinized material;

[0026] (2) Enzymatic hydrolysis: Add a compound enzyme to the gelatinized material and hydrolyze it to obtain the hydrolyzed material;

[0027] (3) Lactic acid bacteria fermentation: Lactic acid bacteria are added to the enzymatically hydrolyzed material and fermented to obtain lactic acid bacteria fermented material;

[0028] (4) Yeast fermentation: Add yeast to the lactic acid bacteria fermentation material and ferment to obtain yeast fermentation material;

[0029] (5) Centrifugation: The yeast fermentation material was centrifuged sequentially using a horizontal screw centrifuge and a disc centrifuge to obtain a centrifuged light liquid;

[0030] (6) Post-treatment: The centrifuged light liquid is filtered through a ceramic membrane to obtain ceramic membrane filtrate; the ceramic membrane filtrate is then treated sequentially with an ion exchange resin column and an activated carbon column to obtain a decolorized liquid;

[0031] (7) Concentration: The decolorized liquid is concentrated under reduced pressure, sterilized by UHT, and packaged to obtain fermented monk fruit concentrate.

[0032] Preferably, in step (1), the various by-products in the production process of the monk fruit extract are a mixture of column effluent from macroporous adsorption resin, decanter centrifuge residue, and heavy liquid from disc centrifuge in a mass ratio of 1:0.01-0.15:0.01-0.15; preferably, the mass ratio of column effluent from macroporous adsorption resin, decanter centrifuge residue, and heavy liquid from disc centrifuge is 1:0.05-0.1:0.05-0.1.

[0033] The effluent from the macroporous adsorption resin column serves as the main liquid phase matrix and carbon source (sugar) supplier for fermentation, providing energy for microbial growth and metabolism. After enzymatic hydrolysis, the decanter residue is converted from proteins into amino acids and peptides, which are important flavor precursors. In subsequent fermentation, amino acids can generate abundant aroma compounds through microbial fermentation and other pathways; some amino acids (such as glutamic acid) also possess umami flavor. Oligosaccharides produced from the enzymatic hydrolysis of crude fiber also contribute to flavor and mouthfeel; however, the proportion of decanter residue added should not be too high, otherwise, excessive low-molecular-weight bitter peptides or certain astringent substances may be produced after enzymatic hydrolysis, leading to a poor taste. The heavy liquid from disc centrifugation is rich in pectin, some soluble proteins, and fine suspended matter. Pectin, after enzymatic hydrolysis, produces galacturonic acid and other substances that contribute a mellow acidity and richness, making the taste fuller and rounder, and increasing the flavor's saturation. However, if the proportion added is too high, it will also bring excessive turbidity and potential off-flavors, increasing the load on subsequent centrifugation and filtration. Incomplete treatment will affect the clarity and purity of the final product. Therefore, the process of this invention requires strict control of the ratio of the column effluent from the macroporous adsorption resin column, the horizontal screw centrifuge residue, and the heavy liquid from disc centrifugation to obtain a monk fruit concentrate with excellent taste and flavor and a unique fermented fruit aroma.

[0034] Preferably, in step (1), the heating temperature is 90-100℃, and the holding time is 1-3 hours. One purpose of high-temperature gelatinization is to allow the water-insoluble components in the monk fruit by-product to fully expand, which is beneficial to subsequent enzymatic hydrolysis and fermentation; the second purpose is sterilization to prevent the presence of miscellaneous bacteria from affecting fermentation.

[0035] Preferably, in step (2), the compound enzyme is a mixture of protease, pectinase, cellulase, and hemicellulase; more preferably, the weight ratio of protease, pectinase, cellulase, and hemicellulase is 1:0.5-1:0.5-1:0.1-0.5. The total amount of the compound enzyme is 0.01%-0.5% of the weight of the monk fruit by-product gelatinized material. The purpose of adding the compound enzyme is to enzymatically decompose the macromolecules in the monk fruit by-product gelatinized material into small molecules such as amino acids, galacturonic acid, oligosaccharides, and monosaccharides.

[0036] Preferably, in step (3), the lactic acid bacteria include, but are not limited to, *Lactobacillus acidophilus*, *Lactobacillus lactis*, *Lactobacillus bulgaricus*, *Streptococcus lactis*, *Streptococcus casei*, *Streptococcus thermophilus*, *Leuconostoc mesenteroides*, *Leuconostoc stomatitis*, *Bifidobacterium*, *Bifidobacterium infantis*, and *Bifidobacterium adolescentis*. The purpose of lactic acid bacteria fermentation is threefold: first, to produce lactic acid; second, to produce amino acids that improve flavor; and third, to produce B vitamins beneficial to human health. The inoculum size (cell concentration) of lactic acid bacteria is 10... 6 -10 7 CFU / mL.

[0037] Preferably, in step (4), the yeast includes, but is not limited to, *Saccharomyces cerevisiae*, *Eleocharis ellipticus*, *Kalmarella*, and *Hansenula anomala*. The purpose of yeast fermentation is twofold: first, to produce a small amount of alcohol; and second, to produce amino acids and vitamins beneficial to human health. The inoculum size (cell concentration) of yeast is 10... 5 - 10 6 CFU / mL.

[0038] The fermentation order of steps 3 and 4 cannot be reversed; changing the order will lead to a deterioration in taste. The inventors speculate that the possible reason is that during lactic acid bacteria fermentation, they can rapidly utilize sugars to produce a large amount of lactic acid, lowering the pH of the system. Low pH and microaerobic environments significantly affect their metabolic pathways. Under these conditions, the yeast's alcoholic fermentation (converting sugar into ethanol) is partially inhibited, and it tends to undergo metabolism primarily focused on producing flavor compounds (higher alcohols and esters). This ensures that the product has a low ethanol content (<0.5%), but with prominent fruit and alcohol aromas. In the acidic environment created by lactic acid bacteria, the yeast utilizes the remaining sugars and precursors for fermentation. Its metabolites interact in complex ways with the metabolites of lactic acid bacteria, forming a richer and more harmonious fermented fruit aroma. If the order is reversed, the yeast will produce ethanol first, and the lactic acid bacteria may not be able to compete effectively later, resulting in an overall flavor that leans towards alcohol rather than fermented fruit and acid aromas.

[0039] Preferably, in step (5), the separation factor of the horizontal decanter centrifuge is greater than 2500, and the separation factor of the disc centrifuge is greater than 3000. The purpose of using the horizontal decanter centrifuge and the disc centrifuge is to remove some of the insoluble matter in the fermented material, which facilitates subsequent processing.

[0040] Preferably, in step (6), the pore size of the ceramic membrane is 1-20 μm, more preferably 10-20 μm. The purpose of using ceramic membrane filtration is to further clarify the material and fully remove insoluble matter; the ion exchange resin includes cation exchange resin and anion exchange resin. Among them, the types of cation exchange resin include, but are not limited to, styrene-type and acrylic-type, and the models of cation exchange resin include, but are not limited to, 001×7, 732, 001×8, 001×16, D001, D113; the types of anion exchange resin include, but are not limited to, styrene-type and acrylic-type, and the models of anion exchange resin include, but are not limited to, 201×7, 717, 202, 213, D201, D202, D941, D945, LX-T5, LXD-762, LX-94. The purpose of using cation exchange resin is mainly for desalination, while the purpose of using anion exchange resin is mainly for decolorization. The activated carbon is granular, and the height-to-diameter ratio of the activated carbon column is 1:1-8:1. The flow rate of the material through the activated carbon column is 0.5-2.0 BV / hour. The purpose of using the activated carbon column is to remove odors.

[0041] Preferably, in step (7), the temperature of the vacuum concentration is 50-80°C, and the sugar content of the concentrated juice is 45-75 Brix.

[0042] In the method of this invention, 1 BV = 1 column volume.

[0043] The production process of monk fruit extract yields various byproducts rich in natural nutrients, making them excellent dietary supplements. However, due to the solubility and taste deficiencies of some components, their full development and utilization are hindered, instead becoming a burden on environmental protection and waste treatment. This invention provides a monk fruit concentrate rich in enzymes and its preparation method. First, enzymatic hydrolysis is used to degrade the water-insoluble natural components; then, microbial fermentation is used to convert macromolecules into small-molecule nutrients beneficial to the human body; finally, natural product separation and purification methods are used to obtain a fermented monk fruit concentrate with good solubility, pure taste, and rich nutrients.

[0044] This invention utilizes the residue from horizontal screw centrifugation and the heavy liquid from disc centrifugation, which are difficult to utilize in existing technologies, and mixes them with the effluent from a macroporous adsorption resin column according to a specific mass. Then, the mixture undergoes high-temperature gelatinization, enzymatic hydrolysis, lactic acid bacteria fermentation, yeast fermentation, centrifugation, filtration, desalting and decolorization, and concentration to obtain a high-quality fermented monk fruit concentrate. This concentrate is a light yellow, transparent liquid with a fruity aroma, a sweet and sour taste, and is rich in lactic acid and vitamin B.

[0045] This invention provides a novel method for preparing fermented monk fruit concentrate, which comprehensively utilizes various byproducts generated during the production and processing of monk fruit and is suitable for industrial-scale mass production. This method uses the horizontal screw centrifuge residue and disc centrifuge heavy liquid, which are currently difficult to process in large quantities in the monk fruit industry, as two raw materials. This solves a pain point in the industry, provides a reference for other industries, and features a continuous, simple, and highly operable process with low production costs. Attached Figure Description

[0046] Figure 1 This is a schematic diagram of the byproducts generated during the production of Luo Han Guo V50. Detailed Implementation

[0047] The present invention will be further described below with reference to the embodiments.

[0048] The various byproducts used in the production process of monk fruit extract in this embodiment of the invention (such as: column effluent from macroporous adsorption resin, decanter centrifuge residue, and disc centrifuge heavy liquid) were all taken from the monk fruit extract production workshop of Hunan Huacheng Bioresources Co., Ltd. Specifically, the decanter centrifuge residue is a semi-solid residue (78.55% moisture content) continuously discharged from the decanter centrifuge after the hot water extract of monk fruit has been processed; the disc centrifuge heavy liquid is a thick, rice-water-like residue (89.60% moisture content) periodically discharged from the disc centrifuge during material processing (collecting the centrifuge liquid from the decanter centrifuge); and the column effluent from macroporous adsorption resin refers to the liquid material (95.73% moisture content) flowing out from the bottom of the macroporous adsorption resin column after the macroporous adsorption resin adsorbs monk fruit glycosides. The horizontal screw centrifuge and disc centrifuge used in the embodiments of the invention were purchased from Jiangsu Juneng Machinery Co., Ltd.; the ceramic membrane used in the embodiments of the invention was purchased from Nanjing Fulinde Environmental Protection Technology Co., Ltd.; the anion and cation exchange resins used in the embodiments of the invention were purchased from Xi'an Lanxiao Technology New Material Co., Ltd.; the activated carbon used in the embodiments of the invention was purchased from Jiangsu Pushida Environmental Protection Technology Co., Ltd.; and the auxiliary materials or chemical reagents used in the embodiments of the invention, unless otherwise specified, were obtained through conventional commercial channels.

[0049] In this embodiment of the invention, an electronic pH meter is used to detect the pH value, gas chromatography is used to detect the ethanol content, acid-base titration is used to determine the total acid content, and high performance liquid chromatography (HPLC) external standard method is used to detect the total vitamin B content.

[0050] Example 1

[0051] (1) High temperature gelatinization: Take the following by-products from the production process of monk fruit extract: 5000 kg of column effluent from macroporous adsorption resin column, 500 kg of horizontal screw centrifuge residue, and 500 kg of heavy liquid from disc centrifuge, mix them, stir evenly, heat to 96℃, keep warm for 2 hours, and cool to room temperature to obtain the gelatinized material of monk fruit by-products.

[0052] (2) Enzymatic hydrolysis: Add 3.5 kg of compound enzyme (the weight ratio of protease, pectinase, cellulase and hemicellulase is 1:1:1:0.5) to the gelatinized material of Luo Han Guo by-products and hydrolyze for 4 hours to obtain the enzymatic hydrolysate of Luo Han Guo by-products;

[0053] (3) Lactic acid bacteria fermentation: Add Lactobacillus acidophilus to the enzymatic hydrolysate of Luo Han Guo by-products, ferment for 10 hours, and when the pH value of the fermentation liquid is <5 and the lactic acid HPLC content is ≥0.05%, stop the lactic acid bacteria fermentation and obtain the lactic acid bacteria fermented material of Luo Han Guo by-products;

[0054] (4) Yeast fermentation: Add brewing yeast to the lactic acid bacteria fermentation material of Luo Han Guo by-product, ferment for 8 hours, and when the ethanol content in the fermentation liquid is ≥0.2%, stop the yeast fermentation to obtain the yeast fermentation material of Luo Han Guo by-product;

[0055] (5) Centrifugation: The fermentation material of the by-product yeast of Luo Han Guo was centrifuged in sequence using a horizontal screw centrifuge (separation factor 2580) and a disc centrifuge (separation factor 4000) to obtain a centrifuged light liquid;

[0056] (6) Filtration: The centrifuged light liquid is filtered through a ceramic membrane (filtration pore size of 10 micrometers) to obtain ceramic membrane filtrate;

[0057] (7) Desalination, decolorization, and deodorization: The ceramic membrane filtrate is passed sequentially through an anion exchange resin column (styrene type, resin model 201×7, resin volume 200L, resin column height-to-diameter ratio = 5:1), a cation exchange resin column (styrene type, resin model 001×7, resin volume 200L, resin column height-to-diameter ratio = 5:1), and an activated carbon column (granular coconut shell activated carbon, particle size 0.6-2.36mm, volume 100L, activated carbon column height-to-diameter ratio = 6:1) at a flow rate of 1.0 BV / hour to obtain a decolorized solution;

[0058] (8) Concentration: The decolorized liquid is concentrated under reduced pressure at 70°C until the sugar content is 65°Brix. It is then sterilized by UHT and packaged to obtain the fermented monk fruit concentrate.

[0059] The fermented monk fruit concentrate obtained in this embodiment is a light yellow, transparent liquid with a fruity aroma and a sweet and sour taste. High-performance liquid chromatography (HPLC) using the external standard method showed that the content of mogroside V in the fermented monk fruit concentrate obtained in this embodiment was 1.09%; the pH value of the fermented monk fruit concentrate obtained in this embodiment was 5.5, as determined by an electronic pH meter; the ethanol content of the fermented monk fruit concentrate obtained in this embodiment was 0.23%, as determined by gas chromatography; the total acid content of the fermented monk fruit concentrate obtained in this embodiment was 2.32%, as determined by acid-base titration; and the total vitamin B content of the fermented monk fruit concentrate obtained in this embodiment was 4.12 ppm, as determined by HPLC using the external standard method.

[0060] Example 2

[0061] (1) High temperature gelatinization: Take the following by-products from the production process of monk fruit extract: 5000 kg of column effluent from macroporous adsorption resin column, 250 kg of horizontal screw centrifuge residue, and 250 kg of heavy liquid from disc centrifuge, mix them, stir evenly, heat to 96℃, keep warm for 2 hours, and cool to room temperature to obtain the gelatinized material of monk fruit by-products.

[0062] (2) Enzymatic hydrolysis: Add 3.0 kg of compound enzyme (the weight ratio of protease, pectinase, cellulase and hemicellulase is 1:1:0.5:0.5) to the gelatinized material of Luo Han Guo by-products and hydrolyze for 6 hours to obtain the enzymatic hydrolysate of Luo Han Guo by-products;

[0063] (3) Lactic acid bacteria fermentation: Lactobacillus lactis was added to the enzymatic hydrolysate of Luo Han Guo by-products and fermented for 9 hours. The pH value of the fermentation liquid was measured to be <5 and the lactic acid HPLC content was ≥0.05%. Lactic acid bacteria fermentation was stopped to obtain the lactic acid bacteria fermented material of Luo Han Guo by-products.

[0064] (4) Yeast fermentation: Elliptical yeast was added to the lactic acid bacteria fermentation material of Luo Han Guo by-product, and fermented for 10 hours. The ethanol content in the fermentation liquid was measured to be ≥0.2%. The yeast fermentation was stopped to obtain the yeast fermentation material of Luo Han Guo by-product.

[0065] (5) Centrifugation: The fermentation material of the by-product yeast of Luo Han Guo was centrifuged in sequence using a horizontal screw centrifuge (separation factor 2580) and a disc centrifuge (separation factor 4000) to obtain a centrifuged light liquid;

[0066] (6) Filtration: The centrifuged light liquid is filtered through a ceramic membrane (filtration pore size of 20 micrometers) to obtain ceramic membrane filtrate;

[0067] (7) Desalination, decolorization, and deodorization: The ceramic membrane filtrate is passed sequentially through an anion exchange resin column (resin type: acrylic, resin model: D941, resin volume: 200L, resin column height-to-diameter ratio: 5:1), a cation exchange resin column (resin type: styrene, resin model: 001×16, resin volume: 200L, resin column height-to-diameter ratio: 5:1), and an activated carbon column (granular coconut shell activated carbon, particle size: 0.6-1.7mm, volume: 80L, activated carbon column height-to-diameter ratio: 5.2:1) at a flow rate of 0.8 BV / hour to obtain a decolorized solution;

[0068] (8) Concentration: The decolorized liquid is concentrated under reduced pressure at 76°C until the sugar content is 68°brix. It is then sterilized by UHT and packaged to obtain fermented monk fruit concentrate.

[0069] The fermented monk fruit concentrate obtained in this embodiment is a light yellow, transparent liquid with a fruity aroma and a sweet and sour taste. High-performance liquid chromatography (HPLC) using the external standard method showed that the content of mogroside V in the fermented monk fruit concentrate obtained in this embodiment was 0.37%; the pH value of the fermented monk fruit concentrate obtained in this embodiment was 5.2, as determined by an electronic pH meter; the ethanol content of the fermented monk fruit concentrate obtained in this embodiment was 0.18%, as determined by gas chromatography; the total acid content of the fermented monk fruit concentrate obtained in this embodiment was 2.47%, as determined by acid-base titration; and the total vitamin B content of the fermented monk fruit concentrate obtained in this embodiment was 5.25 ppm, as determined by HPLC using the external standard method.

[0070] Example 3

[0071] The other conditions are the same as in Example 1, except that in step (1), the column effluent from the macroporous adsorption resin column is 5000 kg, the residue from the horizontal screw centrifuge is 200 kg, and the heavy liquid from the disc centrifuge is 200 kg.

[0072] Example 4

[0073] The other conditions are the same as in Example 1, except that in step (1), the column effluent from the macroporous adsorption resin column is 5000 kg, the horizontal screw centrifuge residue is 700 kg, and the disc centrifuge heavy liquid is 700 kg.

[0074] Comparative Example 1

[0075] The other conditions are the same as in Example 1, except that in step (1), no horizontal screw centrifuge residue is added.

[0076] Comparative Example 2

[0077] The other conditions are the same as in Example 1, except that in step (1), no horizontal screw centrifuge residue is added.

[0078] Comparative Example 3

[0079] The other conditions are the same as in Example 1, except that the order of steps (3) and (4) is reversed, that is, yeast fermentation is carried out first, followed by lactic acid bacteria fermentation.

[0080] Comparative Example 4

[0081] The monk fruit concentrate was prepared according to Example 1 of patent CN106923113A. That is, unfermented monk fruit concentrate.

[0082] Application examples

[0083] Does this kind of subjective test include GB (GB) or similar standards?

[0084] Sensory evaluation personnel are selected according to the provisions of GB / T16291.2-2010. After receiving training in odor and taste sensitivity, sensory evaluation personnel are selected and a sensory evaluation team is formed.

[0085] Sensory analysts restricted their diet for one hour before the evaluation experiment, especially avoiding foods that could significantly affect taste. For different taste tests, 20 of the 30 most suitable sensory analysts were selected to conduct blind tasting evaluations of the fermented monk fruit concentrate from the above examples and comparative examples. The samples were uniformly diluted to the same sweetness as a 2% sucrose aqueous solution, i.e., a sweetness multiple of 1. Subjects rated the overall taste of the samples on a scale of 1 to 10, with 1 being the lowest (worst taste) and 10 being the best (satisfactory overall taste). The results are shown in Table 1 below.

[0086] Table 1 Subjective evaluation of monk fruit concentrate

[0087]

[0088] As can be seen, the fermented monk fruit concentrate of this invention has a unique fermented fruit aroma, and the fermented monk fruit concentrate significantly improves the aftertaste and enhances the saturation of the flavor. Compared with the unbleached monk fruit concentrate, the fermented monk fruit concentrate has obvious advantages in terms of clarity and astringency.

Claims

1. A fermented monk fruit concentrate, characterized in that, The following conditions must be met: the content of mogroside V is 0.1-10 wt%, the pH value range is 4.5-6.5, the ethanol content is <0.5 wt%, and the total acid content is ≥1 wt%; the fermented mogroside concentrate is a by-product of the production process of mogroside extract, which is obtained by sequentially undergoing high-temperature gelatinization, enzymatic hydrolysis, lactic acid bacteria fermentation, yeast fermentation, centrifugation, filtration, desalting and decolorization, and concentration; the by-product is a mixture of column effluent from macroporous adsorption resin column, horizontal screw centrifuge residue, and disc centrifuge heavy liquid.

2. The fermented monk fruit concentrate according to claim 1, characterized in that, The fermented monk fruit concentrate has a content of 0.3-1.5% of mogroside V, a pH range of 5.0-6.0, an ethanol content of 0.1-0.4 wt%, and a total acid content of ≥2%.

3. The fermented monk fruit concentrate according to claim 1, characterized in that, The byproduct is a mixture of column effluent from macroporous adsorption resin, decanter centrifuge residue, and disc centrifuge heavy liquid in a mass ratio of 1:0.01~0.15:0.01~0.15; preferably, the mass ratio of column effluent from macroporous adsorption resin, decanter centrifuge residue, and disc centrifuge heavy liquid is 1:0.05~0.1:0.05~0.

1.

4. The method for preparing the fermented monk fruit concentrate according to any one of claims 1-3, characterized in that, Includes the following steps: (1) High-temperature gelatinization: Mix various by-products in the production process of monk fruit extract according to the proportion, stir evenly, and heat, keep warm, and cool down to obtain gelatinized material; (2) Enzymatic hydrolysis: Add a compound enzyme to the gelatinized material and hydrolyze it to obtain the hydrolyzed material; (3) Lactic acid bacteria fermentation: Lactic acid bacteria are added to the enzymatically hydrolyzed material and fermented to obtain lactic acid bacteria fermented material; (4) Yeast fermentation: Add yeast to the lactic acid bacteria fermentation material and ferment to obtain yeast fermentation material; (5) Centrifugation: The yeast fermentation material was centrifuged sequentially using a horizontal screw centrifuge and a disc centrifuge to obtain a centrifuged light liquid; (6) Post-treatment: The centrifuged light liquid is filtered through a ceramic membrane to obtain ceramic membrane filtrate; the ceramic membrane filtrate is then treated sequentially with an ion exchange resin column and an activated carbon column to obtain a decolorized liquid; (7) Concentration: The decolorized liquid is concentrated under reduced pressure, sterilized by UHT, and packaged to obtain fermented monk fruit concentrate.

5. The preparation method according to claim 4, characterized in that, In step (1), the various byproducts in the production process of the monk fruit extract are a mixture of column effluent from macroporous adsorption resin, decanter centrifuge residue, and heavy liquid from disc centrifuge in a mass ratio of 1:0.01-0.15:0.01-0.15; preferably, the mass ratio of column effluent from macroporous adsorption resin, decanter centrifuge residue, and heavy liquid from disc centrifuge is 1:0.05-0.1:0.05-0.

1.

6. The preparation method according to claim 4, characterized in that, In step (1), the heating temperature is 90-100℃, and the holding time is 1-3 hours; and / or, In step (2), the compound enzyme is a mixture of protease, pectinase, cellulase and hemicellulase; preferably, the weight ratio of protease, pectinase, cellulase and hemicellulase is 1:0.5-1:0.5-1:0.1-0.5, and the total amount of compound enzyme is 0.01%-0.5% of the weight of the gelatinized material of monk fruit by-product.

7. The preparation method according to claim 4, characterized in that, In step (3), the lactic acid bacteria include, but are not limited to, Lactobacillus acidophilus, Lactobacillus lactis, Lactobacillus bulgaricus, Streptococcus lactis, Streptococcus casei, Streptococcus thermophilus, Leuconostoc mesenteroides, Leuconostoc stomatitis, Bifidobacterium infantis, Bifidobacterium infantis, and Bifidobacterium adolescentis; preferably, the inoculum size (cell concentration) of the lactic acid bacteria is 10. 6 -10 7 CFU / mL; and / or, In step (4), the yeast includes, but is not limited to, *Saccharomyces cerevisiae*, *Eleocharis elutifera*, *Kalmaria sacchari*, and *Hansenula anomala*; preferably, the inoculum size (cell concentration) of the yeast is 10. 5 - 10 6 CFU / mL.

8. The preparation method according to claim 4, characterized in that, In step (5), the separation factor of the horizontal screw centrifuge is greater than 2500, and the separation factor of the disc centrifuge is greater than 3000.

9. The preparation method according to claim 4, characterized in that, In step (6), the pore size of the ceramic membrane is 1-20 μm, preferably 10-20 μm; the type of cation exchange resin includes, but is not limited to, styrene-type and acrylic-type, and the model of the cation exchange resin includes, but is not limited to, 001×7, 732, 001×8, 001×16, D001, D113; the type of anion exchange resin includes, but is not limited to, styrene-type and acrylic-type, and the model of the anion exchange resin includes, but is not limited to, 201×7, 717, 202, 213, D201, D202, D941, D945, LX-T5, LXD-762, LX-94.

10. The preparation method according to claim 4, characterized in that, In step (7), the temperature of the vacuum concentration is 50-80°C, and the sugar content of the concentrated juice is 45-75°Brix.

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