CN114259000B

CN114259000B - Momordica grosvenori concentrated juice and preparation method thereof

Info

Publication number: CN114259000B
Application number: CN202210004482.2A
Authority: CN
Inventors: 何安乐; 熊瑶; 黄华学; 刘庚贵; 黄�俊; 曾润清; 陈明明; 蒋雪
Original assignee: Shaoyang Huacheng Green Fruit Biotechnology Co ltd
Current assignee: Shaoyang Huacheng Green Fruit Biotechnology Co ltd
Priority date: 2022-01-04
Filing date: 2022-01-04
Publication date: 2024-02-09
Anticipated expiration: 2042-01-04
Also published as: CN114259000A

Abstract

The invention provides a preparation method of momordica grosvenori concentrated juice, which comprises the following steps: a) Sterilizing fructus Siraitiae Grosvenorii, crushing, leaching, and separating solid from liquid to obtain leaching solution; b) Mixing the leaching solution, the color fixative, the cation exchange resin and the acidophilic ferment for fermentation, and carrying out solid-liquid separation to obtain acidophilic ferment liquid; c) Regulating pH of acidophilic fermentation liquor to be alkaline, adding silica gel and alkalophilic fermentation agent for fermentation, and carrying out solid-liquid separation to obtain alkalophilic fermentation liquor; d) Regulating pH of the alkalophilic fermentation liquor to be acidic, passing through a nanofiltration membrane, and collecting trapped fluid; concentrating the trapped liquid, and sterilizing to obtain fructus Siraitiae Grosvenorii concentrated juice. The method can simultaneously reduce the energy value, eliminate green smell similar to grass, and also contain a certain aromatic flavor substance; meanwhile, the method does not need a separate decoloring procedure, can effectively inhibit browning in the fermentation process of the concentrated juice, and is not easy to secondarily brown in the subsequent concentration sterilization and storage processes of the concentrated juice because the browning substrate is greatly reduced in the fermentation process.

Description

Momordica grosvenori concentrated juice and preparation method thereof

Technical Field

The invention relates to the technical field of foods, in particular to a momordica grosvenori concentrated juice and a preparation method thereof.

Background

Momordica grosvenori starts to be loaded into Chinese pharmacopoeia in 1977, and belongs to medicinal and edible traditional Chinese medicine materials. The Chinese medicine is considered to be sweet and sour in taste, cool in nature, enters lung and large intestine meridians, and has the effects of clearing heat and moistening lung, moistening throat and relieving cough, relaxing bowel and the like. Clinically, the medicine is mainly used for treating lung heat dry cough, pharyngalgia aphonia, constipation due to intestinal dryness and the like. The fructus momordicae also has good health-preserving efficacy, can clear heat and cool blood, promote the production of body fluid and relieve cough, smooth intestines and expel toxin, tender skin and benefit skin, moisten lung and resolve phlegm, and can prolong life and beautify face and beautify color.

Fructus Siraitiae Grosvenorii extract (containing mogroside as main ingredient) as new generation natural sweetener is widely concerned and used in fields of food, health product, medicine, etc. At present, the health-care food using the momordica grosvenori extract as the sugar substitute has few varieties, and main products comprise momordica grosvenori juice, momordica grosvenori cake, herbal tea, yoghurt, beverage, dairy products, chocolate, ice cream, moon cakes and the like. The momordica grosvenori extract is used as a sugar substitute basis to develop food such as momordica grosvenori light drink, cake, milk tea, chocolate, soft candy and beverage, and has very broad market prospect and profound significance. The suitable group of the momordica grosvenori extract is a high-end group focusing on health and life quality, and is a group with hyperglycemia, obesity and decayed tooth.

Overnutrition is a major problem in today's society, and the "low sugar", "low fat" and "low calorie" diets are increasingly adapted to the consumer trends of modern people. Fructus Siraitiae Grosvenorii can be used as natural sweetener raw material, and has fresh and refreshing taste and certain physiological function.

The traditional processing technology of the momordica grosvenori concentrated juice is divided into two kinds, one is to take the whole momordica grosvenori as a raw material, and perform the procedures of leaching, solid-liquid separation, clarification, decolorization, concentration and the like, so as to obtain the momordica grosvenori concentrated juice containing the momordica grosvenori glycoside V substances. The other is to take effluent liquid of the upper column after the extraction and separation of the mogroside as raw material, and then to obtain the momordica grosvenori concentrated juice without the mogroside V through the procedures of clarification, decoloration, concentration and the like. No matter what kind of concentrated juice, because it is directly clarification decoloration and concentration of the extract of fructus momordicae, it directly causes that it contains a large amount of high-calorie substances such as carbohydrate and fat, so in actual application contrary to the high sweetness of mogroside V, advantage of low calorie. Meanwhile, the fructus momordicae concentrated juice is similar to fruit and vegetable concentrated juice, and has the problem of easy browning, wherein the browning of the concentrated juice occurs in the production and processing process, and the browning substrate of the concentrated juice is browned in the processes of high temperature, fermentation and the like, and the browning substrate of the concentrated juice slowly occurs in the storage process, so that the low temperature or the addition of a color fixative is generally required. Moreover, if the fructus momordicae concentrated juice is improperly treated at high temperature, the concentrated juice is very easy to cause green grass-like green taste of fresh fruits, so that the taste and quality of the fructus momordicae concentrated juice are affected.

CN108813257a discloses a preparation method of a concentrated juice of fructus momordicae, which is prepared by selecting materials, insolating, crushing, steaming, filtering and concentrating, wherein the process breaks up all the dried fructus momordicae raw materials and seeds, directly causes bitter substances contained in the seeds to be leached together, and causes the concentrated juice to contain bitter; simultaneously, the exposure of the momordica grosvenori in the process can directly lead to the reduction of solid matters in the leaching step, thereby directly reducing the product yield; and contains a large amount of sugar without sugar reduction treatment.

At present, the traditional concentrated juice is basically not subjected to most processes, namely, no removal of nutrient substances such as carbohydrates, fat and the like which are easy to cause the increase of blood sugar; some of the brown stain and secondary brown stain which may occur later in the production process are not improved, so that the prepared concentrated juice presents a certain color or gradually develops color in the later period of storage; meanwhile, repeated membrane filtration, adsorption and other processes also lead to the removal of a large amount of functional substances and waste; the green taste of the fresh fructus momordicae similar to grass is not improved pertinently. All of these factors may affect the yield, quality and flavor mouthfeel of the final product.

Therefore, it is very important to develop a momordica grosvenori concentrated juice and a preparation method thereof, which can simultaneously reduce the energy value, eliminate green taste similar to green grass, and also contain a certain aromatic flavor substance.

Disclosure of Invention

In view of the above, the technical problem to be solved by the present invention is to provide a method for preparing a fructus momordicae juice concentrate, which has low energy value, can eliminate green taste similar to grass, and also contains a certain aromatic flavor substance; meanwhile, the method does not need a separate decoloring procedure, and can effectively inhibit browning in the process of fermenting the concentrated juice.

The invention provides a preparation method of momordica grosvenori concentrated juice, which comprises the following steps:

a) Sterilizing fructus Siraitiae Grosvenorii, crushing, leaching, and separating solid from liquid to obtain leaching solution;

b) Mixing the leaching solution, the color fixative, the cation exchange resin and the acidophilic ferment for fermentation, and carrying out solid-liquid separation to obtain acidophilic ferment liquid;

c) Regulating pH of acidophilic fermentation liquor to be alkaline, adding silica gel and alkalophilic fermentation agent for fermentation, and carrying out solid-liquid separation to obtain alkalophilic fermentation liquor;

d) Regulating pH of the alkalophilic fermentation liquor to be acidic, passing through a nanofiltration membrane, and collecting trapped fluid; concentrating the trapped liquid, and sterilizing to obtain fructus Siraitiae Grosvenorii concentrated juice.

Preferably, the sterilization in the step A) is steam sterilization, and the steam sterilization time is 10-20 s; the crushing is specifically crushing of the shell of the fructus momordicae, and the seeds are dispersed but not damaged;

the leaching is carried out by adopting water as leaching liquid; the mass ratio of the fresh fructus momordicae to the water is 1: (3-6); the leaching temperature is 80-100 ℃; the leaching time is 2-4 hours; the leaching process further comprises the step of filtering by adopting an ultrafiltration membrane, wherein the interception molecular weight of the ultrafiltration membrane is 50000-200000 Da.

Preferably, the color fixative in the step B) is sodium bisulphite; the addition amount of the color fixative is 0.01-0.1% of the weight of the leaching solution;

the cation exchange resin is a strong acid cation exchange resin; the model of the cation exchange resin is any one of LXB-001, LSI-101 or 001X 7; the addition amount of the cation exchange resin is 6-10% of the volume of the leaching solution.

Preferably, the acidophilic starter in the step B) is a mixture of rhizopus and lactobacillus; the ratio of the effective viable count of the rhizopus to the effective viable count of the lactic acid bacteria is 1:0.2-0.7; the addition amount of the acidophilic ferment is 0.05-0.2% of the weight of the leaching solution.

Preferably, the pH value of the acidophilic fermentation in the step B) is 4.5-6; the acidophilic fermentation temperature is 35-55 ℃, and the acidophilic fermentation specifically comprises the following steps: the early fermentation time is 24-36 h, and the open state is turned once every 0.5 h; the later fermentation time is 12-24 h, and the sealed fermentation is performed.

Preferably, the adjusting the pH to alkaline in step C) is specifically: adjusting the pH value to 8-10 by alkali; the alkali is sodium hydroxide or potassium hydroxide; the silica gel is 200-300 meshes; the addition amount of the silica gel is 3% -8% of the volume of the leaching solution;

the alkalophilic starter is alkalophilic bacillus or alkalophilic actinomycetes; the addition amount of the alkalophilic fermentation agent is 0.02-0.1% of the weight of the leaching solution.

Preferably, the fermentation of step C) is specifically: the fermentation temperature is 35-55 ℃, the fermentation time is 12-24 h, and the fermentation is performed once every 0.5h in the open state;

the solid-liquid separation is specifically as follows: filtering with 200-300 mesh filter cloth, and filtering with ultrafilter membrane with molecular weight cut-off of 10000-50000 dalton.

Preferably, in the step D), the pH value is regulated to be acidic, specifically, the pH value is regulated to be 6.5-7 by using acid; the acid is any one of citric acid, malic acid, hydrochloric acid or acetic acid; the nanofiltration membrane is specifically a nanofiltration membrane with a molecular weight cutoff of 300-500 daltons.

Preferably, the sterilization temperature in the step D) is 130-140 ℃ and the sterilization time is 2-5 s.

The invention provides a momordica grosvenori concentrated juice which is prepared by the preparation method according to any one of the technical schemes.

Compared with the prior art, the invention provides a preparation method of fructus momordicae concentrated juice, which comprises the following steps: a) Sterilizing fructus Siraitiae Grosvenorii, crushing, leaching, and separating solid from liquid to obtain leaching solution; b) Mixing the leaching solution, the color fixative, the cation exchange resin and the acidophilic ferment for fermentation, and carrying out solid-liquid separation to obtain acidophilic ferment liquid; c) Regulating pH of acidophilic fermentation liquor to be alkaline, adding silica gel and alkalophilic fermentation agent for fermentation, and carrying out solid-liquid separation to obtain alkalophilic fermentation liquor; d) Regulating pH of the alkalophilic fermentation liquor to be acidic, passing through a nanofiltration membrane, and collecting trapped fluid; concentrating the trapped liquid, and sterilizing to obtain fructus Siraitiae Grosvenorii concentrated juice. The method can simultaneously reduce the energy value, eliminate green smell similar to grass, and also contain a certain aromatic flavor substance; meanwhile, the method does not need a separate decoloring procedure, can effectively inhibit browning in the fermentation process of the concentrated juice, and as the browning substrates (amino acid, sugar and the like) are greatly reduced in the fermentation process, the concentrated juice is not easy to undergo secondary browning in the subsequent concentration sterilization and storage processes, and the storage property is greatly improved; the product is colorless, clear and transparent, low in energy value, simple in production process, strong in industrialization capability and high in crowd acceptance.

Detailed Description

The invention provides a fructus momordicae concentrated juice and a preparation method thereof, and a person skilled in the art can properly improve the technological parameters by referring to the content of the invention. It is expressly noted that all such similar substitutions and modifications will be apparent to those skilled in the art, and they are intended to be within the scope of the present invention. While the methods and applications of this invention have been described in terms of preferred embodiments, it will be apparent to those skilled in the relevant art that the invention can be practiced and practiced with modification and alteration and combination of the methods and applications herein without departing from the spirit and scope of the invention.

The preparation method of the momordica grosvenori concentrated juice provided by the invention comprises the steps of sterilizing momordica grosvenori.

The fructus momordicae is a complete fruit with golden yellow surface, no putrefaction and no rot.

The sterilization is steam sterilization, and the specific method is that the momordica grosvenori passes through boiling water and is kept in the boiling water for 10-20 s.

The sterilization is followed by crushing. The crushing is specifically crushing of the shell of the fructus momordicae, and the seeds are dispersed but not damaged; the method comprises the following steps: crushing shell of fructus Siraitiae Grosvenorii, kneading and dispersing, and keeping the whole kernel integrity without breakage.

Crushing the fresh fructus momordicae and leaching. The leaching is carried out by taking water as leaching solvent, and extracting by pot-type extraction or continuous countercurrent extraction. The mass ratio of the fresh fructus momordicae to the water is 1:3-6; the mass ratio of the dried fructus momordicae to the water feed liquid is 1:15-30; the leaching temperature is preferably 80-100 ℃; more preferably 85 to 95 ℃; the leaching time is 2-4 h.

And (3) carrying out solid-liquid separation after leaching to obtain leaching liquor. The solid-liquid separation aims at realizing separation of extraction slag and extraction liquid, and comprises any one or combination of horizontal screw centrifugation and disc centrifugation, wherein the horizontal screw centrifugation is more preferred, and then the disc centrifugation is carried out.

The leaching also comprises the step of filtering by adopting an ultrafiltration membrane, wherein the molecular weight cut-off of the ultrafiltration membrane is preferably 50000-200000 Da; more preferably 80000 to 150000Da.

Mixing the leaching solution, color fixative, cation exchange resin and acidophilic starter for fermentation.

The color fixative is sodium bisulphite; the addition amount of the color fixative is preferably 0.01-0.1% of the weight of the leaching solution; more preferably 0.02% to 0.08%.

The sodium bisulphite color fixative is added in the invention, which can inhibit browning reaction in the fermentation process, thereby ensuring that fermentation liquor does not change color in the acidophilic fermentation process.

The cation exchange resin is strong acid cation exchange resin; the model of the cation exchange resin is any one of LXB-001, LSI-101 or 001X 7; the addition amount of the cation exchange resin is preferably 6-10% of the volume of the leaching solution; more preferably from 6.5% to 9.5%.

The inventor discovers that the cation exchange resin can have a certain adsorption and decoloration effect on pigments in the system, ensure that fermentation liquor is colorless, and can be used as an acid-base buffer agent so as to maintain the stability of the pH of the system, thereby promoting the acidophilic fermentation.

The acidophilic starter is a mixture of rhizopus and lactobacillus; the ratio of the effective viable count of the rhizopus to the effective viable count of the lactic acid bacteria is 1:0.2-0.7; the addition amount of the acidophilic ferment is preferably 0.05-0.2% of the weight of the leaching solution; more preferably 0.08 to 0.18%.

The fermentation is acidophilic fermentation, and pH is regulated to 4.5-6 before acidophilic fermentation. The acid used for regulating the pH is any one of malic acid, citric acid, hydrochloric acid and acetic acid.

The acidophilic fermentation is preferably specifically: the acidophilic fermentation temperature is 35-55 ℃, the primary fermentation time is 24-36 h, and the open state is turned once every 0.5 h; the later fermentation time is 12-24 hours, and the sealed fermentation is performed; more preferably specifically: the acidophilic fermentation temperature is 38-52 ℃, the primary fermentation time is 26-33 h, and the open state is turned once every 0.5 h; the later fermentation time is 15-22 h, and the sealed fermentation is performed.

Solid-liquid separation is carried out after acidophilic fermentation to obtain acidophilic fermentation liquid. The solid-liquid separation is carried out by a filter cloth bag with 200-300 meshes.

The pH of the acidophilic fermentation broth was adjusted to alkaline. The invention relates to a method for adjusting pH to be alkaline, which comprises the following steps: adjusting the pH value to 8-10 by alkali; the alkali is sodium hydroxide or potassium hydroxide.

And (3) regulating the pH value of the acidophilic fermentation liquid to be alkaline, and adding silica gel and an alkalophilic fermentation agent for fermentation.

The silica gel is 200-300 meshes; the addition amount of the silica gel is 3% -8% of the volume of the leaching solution;

the alkalophilic starter is alkalophilic bacillus or alkalophilic actinomycetes; the addition amount of the alkalophilic fermentation agent is preferably 0.02% -0.1% of the weight of the leaching solution; more preferably 0.04% to 0.08%.

The fermentation of the invention is preferably specifically: the fermentation temperature is 35-55 ℃, the fermentation time is 12-24 h, and the fermentation is performed once every 0.5h in the open state; more preferably specifically: the fermentation temperature is 37-52 ℃, the fermentation time is 15-22 h, and the fermentation is performed once every 0.5h in the open state.

Solid-liquid separation is carried out after alkalophilic fermentation to obtain alkalophilic fermentation liquor. The solid-liquid separation of the invention is preferably specifically: filtering with 200-300 mesh filter cloth, and filtering with ultrafilter membrane with molecular weight cut-off of 10000-50000 dalton.

The pH of the basophilic fermentation broth is adjusted to be acidic. The pH value is regulated to be acidic, specifically, the pH value is regulated to be 6.5-7 by acid; the acid is any one of citric acid, malic acid, hydrochloric acid or acetic acid.

And (3) regulating the pH value of the alkalophilic fermentation liquor to be acidic, passing through a nanofiltration membrane, and collecting trapped fluid.

The nanofiltration membrane according to the invention is preferably in particular a nanofiltration membrane having a molecular weight cut-off of 300 to 500 daltons.

Concentrating the trapped liquid, and sterilizing to obtain fructus Siraitiae Grosvenorii concentrated juice.

The concentration according to the present invention is preferably 30 to 50% of the soluble solids in the concentrate.

The sterilization temperature of the invention is preferably 130-140 ℃, and the sterilization time is preferably 2-5 s.

According to the invention, after the sterilized fresh fructus momordicae is crushed, water is extracted to obtain a leaching solution, and acidophilic ferment is added into the leaching solution to perform aerobic fermentation and anaerobic fermentation respectively, so that organic substances (saccharides, starch, proteins, amino acids and the like) in the leaching solution are promoted to be degraded into micromolecular saccharides or amino acids and the like until being further degraded into aromatic substances such as acetic acid, ethyl acetate, ethyl lactate and the like, thereby reducing the energy value of the product and reducing browning substrates; meanwhile, the color fixative is added into the system, which can inhibit browning reaction in the fermentation process, so that the fermentation liquor is ensured not to change color in the acidophilic fermentation process, and the cation exchange resin is added, which can have a certain adsorption decolorization effect on pigment in the system, so that the fermentation liquor is ensured to be colorless, and can be used as an acid-base buffer, so that the stability of the pH of the system is maintained, and acidophilic fermentation is promoted.

After acidophilic fermentation is finished, the pH value is regulated by adding alkali, the color fixative sodium bisulphite is converted into sodium sulfite, the sodium sulfite has the function of inhibiting browning under alkaline conditions, alkaline fermentation bacteria are added for acidophilic fermentation, the energy value in a system can be further reduced, the energy is converted into aromatic substances which are not brown substrates, thus further inhibiting fermentation browning and secondary browning of the product in a storage period, and meanwhile, silica gel with the function of adsorbing pigment is added, and pigment in an alkaline fermentation system can be further adsorbed, so that the fermentation liquor is ensured to be always colorless.

And then regulating the acid of the fermentation liquor, improving the taste, removing sodium salt, sulfite and other ions through nanofiltration, concentrating by a reverse osmosis membrane, and sterilizing to obtain colorless, clear and transparent fructus momordicae concentrated juice.

The method has the beneficial effects that:

1. the energy value of the momordica grosvenori concentrated juice obtained by the invention is extremely low, and the energy value mark is 0, namely less than or equal to 17KJ/100ml.

2. The momordica grosvenori concentrated juice contains various flavor substances, wherein the content of ethyl acetate is more than or equal to 120mg/100ml, and the content of ethyl lactate is more than or equal to 160mg/100ml.

3. The momordica grosvenori concentrated juice obtained by the invention has no need of separate decoloring treatment in the whole working procedure, and can realize colorless, clear and transparent products, stable browning degree and difficult browning and discoloration after long-time storage.

4. The fructus momordicae concentrated juice prepared by the method has pleasant aromatic smell and green taste similar to green grass.

5. The method has the advantages of simple whole process, strong industrialization capability and high crowd acceptance.

In order to further illustrate the present invention, the following examples are provided to describe in detail a fructus momordicae juice concentrate and a preparation method thereof.

The fresh momordica grosvenori used in the embodiment of the invention is provided by Jiangxi Hai bioengineering Limited.

The materials or chemicals used in the examples of the present invention, unless otherwise specified, were obtained by conventional commercial means.

The invention adopts the following method for detection:

(1) The energy value detection method comprises the following steps: the detection is carried out according to the requirements of basic terms of food nutrient components of GB/Z21922-2008.

(2) The detection method of the ethyl acetate comprises the following steps: according to the requirements of GB 1886.190-2016 food safety national standard food additives ethyl acetate.

(3) The detection method of ethyl lactate comprises the following steps: according to the requirements of GB 1886.197-2016 food safety national standard food additives of ethyl lactate.

(4) Degree of browning: the degree of browning is expressed as a percent of browning, i.e., the percent of change in the degree of browning after a period of time. Namely: browning degree= (browning degree T1-browning degree T0)/browning degree T0 x 100%. The greater the browning degree, the more likely it is to brown on storage, and the poorer the product stability.

Wherein:

the browning degree T1 is the measured browning value when the momordica grosvenori concentrated juice is placed for 7 days at the constant temperature of 60 ℃,

the browning degree T0 is the browning degree value of the momordica grove concentrated juice just produced.

Method for measuring browning degree: the concentrated juice is taken, the absorbance value is initially measured at 420nm, and the absorbance value is used for representing the browning degree of the concentrated juice.

(5) Odor evaluation method:

1) Screening and training of sensory analysts

Sensory panelists were screened with reference to the specification of GB/T16291.2-2010, and after odor sensitivity training, 20 sensory panelists (each half of men and women) were finally screened to make up a sensory panel.

2) Selection and attention of sensory analyst

Sensory analysts restricted their diet within 1h before the assessment experiment began, especially foods that could severely affect smell. And selecting 10 most suitable sensory analyzers from 20 to perform sensory evaluation aiming at different olfactory experiments, and calculating an average value after removing the highest score and the lowest score.

3) Sensory scoring criteria

100 parts are fully divided into five grades.

TABLE 1 sensory scoring criteria

Example 1

(1) And (3) sterilization: taking 5kg of fresh fructus momordicae, placing the fresh fructus momordicae in a boiling water bath for 15s, and taking out the fructus momordicae and naturally cooling.

(2) Leaching: crushing the cooled fructus momordicae, adding hot water with the weight being 4 times of that of the cooled fructus momordicae for leaching for 3 times, wherein the temperature of the hot water is 90 ℃, and the leaching time is 3 hours each time, and keeping the stirring state. Filtering with each leaching filter screen, centrifuging with butterfly separator, collecting to obtain 21kg leaching solution, passing through 100000Da ultrafiltration membrane, and collecting clarified permeate.

(3) Acidophilic fermentation: 10g of sodium sulfite and 1.7L of LXB-001 type cation exchange resin are sequentially added into the permeate liquid in the step (2), then hydrochloric acid is used for adjusting the pH value to 5.5, then 21.3g of mixed bacteria (rhizopus: lactobacillus is 1:0.5) are added, after uniform stirring, the mixture is placed in an open state at 50 ℃ for fermentation for 30 hours, and then the temperature is kept for sealed fermentation for 18 hours.

(4) Alkalophilic fermentation: adding sodium hydroxide into the fermentation liquid obtained in the step (3) to adjust the pH value to 8.5, adding 1.3L of 250-mesh silica gel, adding 20g of bacillus alkalophilus, uniformly mixing, and fermenting for 24 hours at 50 ℃ in an open state. Then, the mixture was passed through a 260-mesh filter cloth bag and an ultrafiltration membrane of 20000Da at a time to obtain 18kg of fermentation permeate.

(5) Desalting: the fermentation permeate is adjusted to pH 6.5 by hydrochloric acid, then is filtered through a nanofiltration membrane with molecular weight cut-off of 500 daltons, and the cut-off is collected.

(6) Concentrating: the retentate was concentrated by reverse osmosis to a soluble solids content of 46%.

(7) And (3) sterilization: sterilizing the concentrated solution at 140 ℃ for 3s to obtain 1738ml of colorless, clear and transparent fructus momordicae concentrated juice.

And (3) detecting: the energy value is 13.7KJ/100ml < 17KJ/100ml (namely, the energy value can be identified as 0 calorie), the ethyl acetate is 210mg/100ml, and the ethyl lactate is 280mg/100ml. The browning degree is 3.7%, which shows that the product has excellent stability and stable color. After sensory score of 93.5 minutes, the smell is ideal, and the liquid is colorless, clear and transparent.

Example 2

(1) And (3) sterilization: taking 5kg of fresh fructus momordicae, placing the fresh fructus momordicae in a boiling water bath for 12s, taking out and naturally cooling.

(2) Leaching: crushing the cooled fructus momordicae, adding hot water with the weight being 4 times of that of the cooled fructus momordicae for leaching for 3 times, wherein the temperature of the hot water is 85 ℃, and the leaching time is 2.5 hours each time, and keeping a stirring state. After each filtration of the leaching filter screen, the leaching solution is centrifuged by a butterfly separator, 21kg of leaching solution is collected, and the clarified permeate is collected after the leaching solution passes through an ultrafiltration membrane of 90000 Da.

(3) Acidophilic fermentation: 10g of sodium sulfite and 1.7L of LXB-001 type cation exchange resin are sequentially added into the permeate liquid in the step (2), then hydrochloric acid is used for adjusting the pH value to 5.0, then 20g of mixed bacteria (rhizopus: lactobacillus is 1:0.4) are added, after uniform stirring, the mixture is placed in an open state at 45 ℃ for fermentation for 28 hours, and then the temperature is kept for sealed fermentation for 16 hours.

(4) Alkalophilic fermentation: adding sodium hydroxide into the fermentation liquid obtained in the step (3) to adjust the pH value to 9.5, adding 1.3L of 250-mesh silica gel, adding 21g of actinomycetes alkaline, uniformly mixing, and fermenting for 20 hours at 50 ℃ under an open state. Then passing through a 260-mesh filter cloth bag and an 20000Da ultrafiltration membrane once to obtain 17kg fermentation permeate.

(5) Desalting: the fermentation permeate was adjusted to pH 6.7 with hydrochloric acid, then passed through nanofiltration membrane with molecular weight cut-off of 450 daltons, and the cut-off was collected.

(6) Concentrating: the retentate was concentrated by reverse osmosis to a soluble solids content of 48.3%.

(7) And (3) sterilization: sterilizing the concentrated solution at 140 deg.C for 3s to obtain 1660ml of colorless, clear and transparent fructus Siraitiae Grosvenorii concentrated juice.

And (3) detecting: the energy value is 12.8KJ/100ml < 17KJ/100ml (namely, the energy value can be identified as 0 calorie), the ethyl acetate is 198mg/100ml, and the ethyl lactate is 258mg/100ml. The browning degree is 4.1%, which shows that the product has excellent stability and stable color. After sensory score of 92.8 minutes, the smell is ideal, and the liquid is colorless, clear and transparent.

Example 3

(1) And (3) sterilization: taking 5kg of fresh fructus momordicae, placing the fresh fructus momordicae in a boiling water bath for 18s, taking out and naturally cooling.

(2) Leaching: crushing the cooled fructus momordicae, adding hot water with the weight being 4 times of that of the cooled fructus momordicae for leaching for 3 times, wherein the temperature of the hot water is 95 ℃, and the leaching time is 3.5 hours each time, and keeping a stirring state. Filtering with each leaching filter screen, centrifuging with butterfly separator, collecting to obtain 21kg leaching solution, passing through 120000Da ultrafiltration membrane, and collecting clear permeate.

(3) Acidophilic fermentation: 10g of sodium sulfite and 1.7L of LSI-101 type cation exchange resin are sequentially added into the permeate liquid in the step (2), then hydrochloric acid is used for adjusting the pH value to 6.0, then 30g of mixed bacteria (rhizopus: lactobacillus is 1:0.6) are added, after uniform stirring, the mixture is placed in an open state at 48 ℃ for fermentation for 32 hours, and then the temperature is kept for sealed fermentation for 20 hours.

(4) Alkalophilic fermentation: adding sodium hydroxide into the fermentation liquid obtained in the step (3) to adjust the pH value to 9, adding 1.3L of 250-mesh silica gel, adding 17g of alkalophilic bacillus, uniformly mixing, and fermenting for 20 hours at 50 ℃ in an open state. Then, the mixture was passed through a 260-mesh filter cloth bag and an ultrafiltration membrane of 20000Da at a time to obtain 18kg of fermentation permeate.

(5) Desalting: the fermentation permeate was adjusted to pH 6.5 with hydrochloric acid, then passed through a nanofiltration membrane with a molecular weight cut-off of 400 daltons, and the retentate was collected.

(6) Concentrating: the retentate was concentrated by reverse osmosis to a soluble solids content of 50.1%.

(7) And (3) sterilization: sterilizing the concentrated solution at 140 deg.C for 3s to obtain 1590ml of colorless, clear and transparent fructus Siraitiae Grosvenorii concentrated juice.

And (3) detecting: the energy value is 14.2KJ/100ml < 17KJ/100ml (namely, the energy value can be identified as 0 calorie), the ethyl acetate is 208mg/100ml, and the ethyl lactate is 273mg/100ml. The browning degree range is 3.9%, which shows that the product has excellent stability and stable color. After the sensory score is 91.7 minutes, the smell is ideal, and the liquid is colorless, clear and transparent.

Comparative example 1

(3) Acidophilic fermentation: 10g of sodium sulfite and 1.7L of LXB-001 type cation exchange resin are sequentially added into the permeate liquid in the step (2), then hydrochloric acid is used for adjusting the pH value to 5.5, then 21.3g of mixed bacteria (rhizopus: lactobacillus is 1:0.05) are added, after uniform stirring, the mixture is placed in an open state at 50 ℃ for fermentation for 30 hours, and then the temperature is kept for sealed fermentation for 18 hours.

(7) And (3) sterilization: sterilizing the concentrated solution at 140 ℃ for 3s to obtain 1743ml of golden-yellow momordica grosvenori concentrated juice.

And (3) detecting: the energy value is 37.7KJ/100ml > 17KJ/100ml (i.e. not identifiable as 0 calories), 89mg/100ml of ethyl acetate and 137mg/100ml of ethyl lactate. The browning degree is 14.5%, which indicates that the product has poor stability and unstable color. After sensory score of 85.3, the smell is also not ideal, the liquid is golden yellow, and the color is not ideal.

Comparative example 2

(3) Acidophilic fermentation: 10g of ascorbic acid and 1.7L of LXB-001 type cation exchange resin are sequentially added into the permeate liquid in the step (2), then hydrochloric acid is used for adjusting the pH value to 5.5, then 21.3g of mixed bacteria (rhizopus: lactobacillus is 1:0.5) are added, after uniform stirring, the mixture is placed in an open state at 50 ℃ for fermentation for 30 hours, and then the temperature is kept for sealed fermentation for 18 hours.

(6) Concentrating: the retentate was concentrated by reverse osmosis to a soluble solids content of 47.2%.

(7) And (3) sterilization: sterilizing the concentrated solution at 140 ℃ for 3s to obtain 1702ml of golden-yellow momordica grosvenori concentrated juice.

And (3) detecting: the energy value is 14.1KJ/100ml < 17KJ/100ml (namely, the energy value can be identified as 0 calorie), the ethyl acetate is 204mg/100ml, and the ethyl lactate is 272mg/100ml. The browning degree is 38.2%, which shows that the product has extremely poor stability and extremely unstable color. The sensory score was 78.3, the smell was not ideal, the liquid was golden yellow, and the color was not ideal.

Comparative example 3

(4) Alkalophilic fermentation: adding sodium hydroxide into the fermentation liquid obtained in the step (3) to adjust the pH value to 8.5, adding 1.3L of 250-mesh D101 macroporous adsorption resin, adding 20g of bacillus alkalophilus, uniformly mixing, and fermenting for 24 hours in an open state at 50 ℃. Then, the mixture was passed through a 260-mesh filter cloth bag and an ultrafiltration membrane of 20000Da at a time to obtain 18kg of fermentation permeate.

(6) Concentrating: the retentate was concentrated by reverse osmosis to a soluble solids content of 46.6%.

(7) And (3) sterilization: sterilizing the concentrated solution at 140 ℃ for 3s to obtain 1682ml of golden yellow momordica grosvenori concentrated juice.

And (3) detecting: the energy value is 13.2KJ/100ml < 17KJ/100ml (namely, the energy value can be identified as 0 calorie), the ethyl acetate is 192mg/100ml, and the ethyl lactate is 203mg/100ml. The browning degree is 27.3%, which shows that the product has extremely poor stability and extremely unstable color. After the sensory score is 83.2 minutes, the smell is not ideal, the liquid is golden yellow, and the color is not ideal.

Comparative example 4

(3) Acidophilic fermentation: sequentially adding 10g of sodium sulfite and 1.7L of AB-8 type macroporous adsorption resin into the permeate liquid in the step (2), then adjusting the pH value to 5.5 by using hydrochloric acid, then adding 21.3g of mixed bacteria (rhizopus: lactobacillus is 1:0.5), uniformly stirring, fermenting for 30 hours at 50 ℃ under an open state, and then keeping the temperature for sealing fermentation for 18 hours.

(6) Concentrating: the retentate was concentrated by reverse osmosis to a soluble solids content of 47.1%.

(7) And (3) sterilization: sterilizing the concentrated solution at 140 deg.C for 3s to obtain 1682ml of colorless, clear and transparent fructus Siraitiae Grosvenorii concentrated juice.

And (3) detecting: the energy value is 24.3KJ/100ml > 17KJ/100ml (i.e. not identifiable as 0 calories), the ethyl acetate is 79mg/100ml, and the ethyl lactate is 98mg/100ml. The browning degree is 18.2%, which shows that the product has extremely poor stability and extremely unstable color. After the sensory score is 87.3 minutes, the smell is not ideal, the liquid is golden yellow, and the color is not ideal.

Comparative example 5

(4) Alkalophilic fermentation: adding sodium hydroxide into the fermentation liquid obtained in the step (3) to adjust the pH value to 8.5, adding 1.3L of 250-mesh silica gel, adding 20g of saccharomycetes, uniformly mixing, and fermenting for 24 hours in an open state at 50 ℃. Then, the mixture was passed through a 260-mesh filter cloth bag and an ultrafiltration membrane of 20000Da at a time to obtain 18kg of fermentation permeate.

(6) Concentrating: the retentate was concentrated by reverse osmosis to a soluble solids content of 46.2%.

(7) And (3) sterilization: sterilizing the concentrated solution at 140 ℃ for 3s to obtain 1708ml of golden-yellow momordica grosvenori concentrated juice.

And (3) detecting: the energy value is 13.7KJ/100ml < 17KJ/100ml (namely, the energy value can be identified as 0 calorie), the ethyl acetate is 132mg/100ml, and the ethyl lactate is 201mg/100ml. The browning degree is 24.2%, which shows that the product has extremely poor stability and extremely unstable color. After sensory score of 81.2, the smell is more ideal, the liquid is golden yellow, and the color is not ideal.

The foregoing is merely a preferred embodiment of the present invention and it should be noted that modifications and adaptations to those skilled in the art may be made without departing from the principles of the present invention, which are intended to be comprehended within the scope of the present invention.

Claims

1. A method for preparing a concentrated juice of momordica grosvenori, comprising the steps of:

b) Mixing the leaching solution, the color fixative, the cation exchange resin and the acidophilic ferment for fermentation, and carrying out solid-liquid separation to obtain acidophilic ferment liquid; the color fixative is sodium bisulphite; the addition amount of the color fixative is 0.01% -0.1% of the weight of the leaching solution; the cation exchange resin is a strong acid cation exchange resin;

the acidophilic starter is a mixture of rhizopus and lactobacillus; the ratio of the effective viable count of rhizopus to the effective viable count of lactobacillus is 1:0.2-0.7; the addition amount of the acidophilic ferment is 0.05-0.2% of the weight of the leaching solution;

c) Regulating pH of acidophilic fermentation liquor to be alkaline, adding silica gel and alkalophilic fermentation agent for fermentation, and carrying out solid-liquid separation to obtain alkalophilic fermentation liquor; the alkalophilic starter is alkalophilic bacillus or alkalophilic actinomycetes; the addition amount of the alkalophilic fermentation agent is 0.02% -0.1% of the weight of the leaching solution;

2. The method according to claim 1, wherein the sterilization in step a) is steam sterilization, and the time of steam sterilization is 10-20 s; the crushing is specifically crushing of the shell of the fructus momordicae, and the seeds are dispersed but not damaged;

the leaching is carried out by adopting water as leaching liquid; the mass ratio of the fresh fructus momordicae to the water is 1: (3-6); the leaching temperature is 80-100 ℃; the leaching time is 2-4 hours; the leaching process further comprises the step of filtering by adopting an ultrafiltration membrane, wherein the molecular weight cut-off of the ultrafiltration membrane is 50000-200000 Da.

3. The method according to claim 1, wherein the cation exchange resin in step B) is any one of model LXB-001 or 001X 7; the addition amount of the cation exchange resin is 6% -10% of the volume of the leaching solution.

4. The method according to claim 1, wherein the pH of the acidophilic fermentation in step B) is 4.5 to 6; the acidophilic fermentation temperature is 35-55 ℃, and the acidophilic fermentation specifically comprises the following steps: the early fermentation time is 24-36 h, and the open state is turned once every 0.5 h; the later fermentation time is 12-24 h, and the sealed fermentation is performed.

5. The method according to claim 1, wherein the adjusting pH to alkaline in step C) is specifically: adjusting the pH value to 8-10 by alkali; the alkali is sodium hydroxide or potassium hydroxide; the silica gel is 200-300 meshes; the addition amount of the silica gel is 3% -8% of the volume of the leaching solution.

6. The method according to claim 1, wherein the fermentation of step C) is specifically: the fermentation temperature is 35-55 ℃, the fermentation time is 12-24 hours, and the fermentation is performed once every 0.5 hour in the open state;

the solid-liquid separation is specifically as follows: filtering with 200-300 mesh filter cloth, and filtering with ultrafiltration membrane with molecular weight cut-off of 10000-50000 daltons.

7. The method according to claim 1, wherein the adjusting of the pH to acidity in step D) is specifically adjusting to 6.5 to 7 with an acid; the acid is any one of citric acid, malic acid, hydrochloric acid or acetic acid; the nanofiltration membrane is specifically a nanofiltration membrane with a molecular weight cutoff of 300-500 daltons.

8. The method according to claim 1, wherein the sterilization temperature in step D) is 130 to 140 ℃ and the sterilization time is 2 to 5s.

9. A concentrated juice of momordica grosvenori, characterized in that it is prepared by the preparation method according to any one of claims 1 to 8.