Pure plant-based ice cream based on wall-broken chlorella and preparation method thereof

Abstract

The invention belongs to the technical field of food processing, and particularly relates to a preparation method of wall-broken chlorella-based pure plant-based ice cream, which comprises the following steps: by taking chlorella with the protein content of more than or equal to 35wt% as a raw material, blending into a chlorella solution with the concentration of 100-200g / L, and carrying out high-pressure homogenization to ensure that more than 80wt% of solid particulate matters in the chlorella solution are less than or equal to 1 mu m; amylase, saccharifying enzyme, cellulase and protease are adopted to conduct enzymolysis on the algae liquid in sequence, so that the hydrolysis degree of starch reaches DE80 or above, and the foaming capacity of the algae liquid reaches 200% or above; s4, thickening, tempering, emulsifying and seasoning the enzymolysis algae pulp by using plant-based food auxiliary materials to obtain ice cream feed liquid, wherein the solid content of the ice cream feed liquid is 33-40% or the viscosity at 25 DEG C is 3000-6000 mPa.s; and S5, making ice cream by using an ice cream machine. According to the invention, the variety of ice cream is enriched, and ideal cold drink food is provided for people who are allergic / intolerant to milk and pursue low-fat and low-heat food.

Description

Technical Field

[0001] The invention belongs to the technical field of food processing, and in particular relates to a pure plant-based ice cream based on cracked chlorella and a preparation method thereof. Background Art

[0002] Chlorella is a widely cultivated microalgae. Chlorella is rich in protein, and its protein content is generally 50-60% (relative to algal cell dry matter), which exceeds beef and soybeans, and has been used as an ingredient for protein nutrition in a variety of foods. Chlorella also contains a variety of unsaturated fatty acids, carotenoids, essential amino acids and other nutrients, with comprehensive nutritional value. It has been listed by the Food and Agriculture Organization of the United Nations as a new raw material for human health food in the 21st century. Chlorella protein has high nutritional value, and its amino acid score is higher than that of common grain proteins. Its content of 9 essential amino acids for humans is higher than that of common grain crops. A large number of studies have shown that Chlorella also contains a variety of bioactive substances, such as ω-3 fatty acids, phosphatidylcholine, sterols, chlorogenic acid, vitamins, nucleic acid-peptide complexes, β-1,3-glucan, signaling molecules, etc. A large number of studies have shown that these bioactive substances have antioxidant, antibacterial, blood sugar regulation, immune regulation, anti-tumor and other effects. In short, Chlorella is not only a source of high-quality protein, but also a food with good health functions. However, due to some shortcomings of Chlorella itself, its application in food is still very limited. For example, chlorella has a characteristic fishy smell that some consumers cannot accept. The cell wall of chlorella is tough and difficult to break, and it feels like hard powder residue. In addition, consuming uncracked chlorella is difficult to digest and causes gastrointestinal discomfort. The active ingredients in chlorella cells are also difficult for the human body to absorb.

[0003] Ice cream has a rich flavor and a soft and refreshing taste. It is a good product for people to cool down in summer and is deeply loved by consumers. At present, the common ice cream on the market generally contains high sugar and fat. As consumers pay more and more attention to health, while satisfying the enjoyment of ice cream, they also hope to reduce energy and fat intake, and it is best to have health effects. At present, ice cream mostly uses milk protein and fat. From the perspective of protein and fat sources, the types of ice cream are relatively fixed. Especially for people who are allergic or intolerant to milk, pursue low calorie intake, control body fat rate, and prefer plant-based foods, it is difficult to find a type of ice cream that suits them. Therefore, if pure plant ice cream can be developed with Chlorella as raw material, it can not only expand the application scope of Chlorella in food, but also enrich the types of ice cream, thus giving people who are allergic or intolerant to milk and prefer plant-based foods a more suitable choice.

[0004] However, there are still some practical problems in using Chlorella as raw material to prepare ice cream, including: First, as mentioned above, the cell wall of Chlorella is very tough, the main component is cellulose, and the nutrients are wrapped in the cells. If the algae powder is directly added to the ice cream, it is difficult for the human body to digest, which will bring a heavy burden to the stomach and intestines, and the nutrients of Chlorella will not be well utilized. Second, ice cream is a frozen food. In addition to its high protein content, Chlorella also has a high content of starch. The gelatinized starch is easy to regenerate under high moisture and freezing low temperature. After the starch is regenerated, the ice cream is full of the unpleasant taste of raw starch (the friction feeling of sandpaper polishing the tongue surface, the generation of taste barriers, and the induction of disgust). Due to these characteristics of Chlorella, there are still technical problems that need to be overcome in making ice cream with Chlorella.

[0005] The currently disclosed prior art for producing ice cream using microalgae as raw materials mainly involves spirulina. For example, CN1565221A and CN 114711323 A disclose a spirulina ice cream powder and a preparation method thereof. This solution uses spirulina (powder) or fresh spirulina without processing the spirulina, and is not suitable for processing chlorella. CN115517312A discloses an ice cream containing spirulina. The ice cream liquid contains 0.01-10.0% of spirulina extract, 10-30% of whole milk powder, 10-20% of whole sweetened condensed milk, 1-3% of cream, 10-20% of sugar, 5-15% of fresh egg slurry, 0.01-0.1% of guar gum, 0.1-1.0% of gelatin, 0.02-0.5% of sodium alginate, 0.01-0.1% of CMC and water. This solution requires the extraction to be separated from spirulina, and the whole algae component is not utilized, thus wasting biomass resources. In addition, the formula contains a large amount of animal-derived protein and fat, which does not meet the needs of people who are allergic or intolerant to animal-derived protein and who prefer pure plant-based food. In addition, CN111758829A discloses a functional seaweed plant ice cream and a preparation method thereof, which uses seaweed powder, prebiotics and probiotics as raw materials, wherein the seaweed powder is spirulina powder or chlorella powder, etc. This scheme uses algae powder to make ice cream, but there are problems such as algae smell, hard powder residue taste and active ingredients are not easy to absorb.

[0006] In summary, the prior art either uses microalgae raw materials directly added to ice cream, which has the problem of bad smell and difficulty in utilizing active ingredients, or requires adding a large amount of exogenous protein foaming agents such as animal milk, whey protein, egg white, etc. Otherwise, the foaming property of the ice cream liquid is poor, the expansion degree is insufficient during whipping, and the produced ice cream is rough and has a non-soft and smooth taste. Summary of the invention

[0007] 1. Technical issues to be resolved

[0008] In view of the above-mentioned shortcomings and deficiencies of the prior art, the present invention provides a method for preparing pure plant-based ice cream based on broken-wall Chlorella, which uses whole algae as food, adopts high-pressure homogenization to treat the algae liquid, and controls the order and degree of enzymatic hydrolysis, reduces the starch content to avoid the taste of retrograde starch in the product and provides sweetness, so that the algae liquid has its own foaming ability, and produces pure plant-based Chlorella ice cream with a soft and smooth taste, high algae protein, low fat and comprehensive nutrition, enriching the categories of new foods of ice cream and Chlorella, and providing more choices for people who are allergic / intolerance to milk and those who prefer pure plant-based foods.

[0009] (II) Technical solution

[0010] In a first aspect, the present invention provides a method for preparing pure plant-based ice cream based on cracked chlorella, comprising the following steps:

[0011] S1. Using Chlorella with a protein content of ≥35wt% as raw material;

[0012] S2, adjusting the chlorella raw material to an algae liquid with a concentration of 100-200 g / L, and treating it with a high-pressure homogenizer to make more than 80 wt % of the solid particles in the algae liquid ≤ 1 μm;

[0013] S3, using amylase, saccharifying enzyme, cellulase and protease to enzymatically hydrolyze the algae liquid in sequence to obtain enzymatically hydrolyzed algae slurry;

[0014] S3, using amylase, saccharifying enzyme, cellulase and protease to enzymatically hydrolyze the algae liquid in sequence to obtain enzymatically hydrolyzed algae slurry; the degree of starch hydrolysis reaches DE80 or above through enzymatic hydrolysis, and the foaming ability of the algae liquid reaches more than 200%;

[0015] S4, thickening, tempering, emulsifying and flavoring the enzymatic algae slurry with plant-based food auxiliary materials to obtain an ice cream liquid, wherein the solid content of the ice cream liquid is 33-40% or the viscosity at 25° C. is 3000-6000 mPa.s;

[0016] S5. Use an ice cream machine to freeze the ice cream liquid into ice cream.

[0017] Among them, the Chlorella raw material in S2 can be aqueous algae liquid or algae powder.

[0018] According to a preferred embodiment of the present invention, the enzymatic hydrolysis process in S3 is as follows:

[0019] S31, adding 400-1000 U / L α-amylase to the algae slurry, heating the algae slurry to 70-90° C. to react until the degree of starch hydrolysis reaches DE15-20;

[0020] S32, cool down to 45-50°C and maintain the temperature, add 1000-5000U / L of cellulase and 5000-10000U / L of saccharifying enzyme until the degree of starch hydrolysis reaches DE80 or above;

[0021] S33, adjusting the pH of the algae liquid to 7.5-9.0, controlling the temperature to 45-50°C, adding 3000-8000U / L of alkaline protease, controlling the hydrolysis degree not to exceed 30% or testing the foaming ability of the algae slurry while hydrolyzing until the foaming ability of the algae liquid is ≥200%;

[0022] S34. Keep the temperature at 110-120℃ for 15-20s to inactivate the enzyme. When inactivating the enzyme, the algae liquid is also sterilized. In order to prevent the chlorophyll-containing Chlorella from fading and browning (producing unpleasant colors) at high temperatures, the high-temperature treatment time of the algae liquid should be shortened as much as possible.

[0023] In S31, the starch hydrolysis degree is firstly increased to DE15-20, and then in S32, the starch is further hydrolyzed until the starch hydrolysis degree reaches DE80 or above, so as to avoid the deterioration of the taste of the ice cream caused by starch retrogradation. In order to obtain soft ice cream, the ice cream liquid must have good foaming ability. In order to minimize the amount of exogenous emulsifier added, the foaming ability of the algae liquid's own protein is utilized. In S33, the degree of protease hydrolysis needs to be controlled, preferably not more than 30%, more preferably 15-25%. At this time, most of the algae protein is hydrolyzed into 3-8kDa peptides. The peptides of this molecular weight have emulsifying properties and better stabilize the gas-liquid interface. Excessive protease hydrolysis, such as hydrolysis degree > 30% or peptides are too short, less than 1kDa or insufficient hydrolysis, are not conducive to foaming.

[0024] Further preferably, the enzymatic hydrolysis in S3 is as follows: S31, adding 1000U / L of medium-temperature α-amylase to the algae slurry, and heating the algae slurry to 80°C to react to gelatinize the starch and immediately hydrolyze it until the degree of hydrolysis reaches DE15-20; S32, cooling to 50°C and maintaining the temperature, adding 3500U / L of cellulase and 8000U / L of saccharifying enzyme, until the degree of hydrolysis of starch is detected to be above DE80; S33, adjusting the pH of the algae liquid to 9.0, regulating the temperature to 45-50°C, adding 3000-8000U / L of alkaline protease, controlling the degree of hydrolysis to 15-25% or the foaming ability of the algae liquid ≥200%; S34, immediately keeping warm at 120°C for 15s to inactivate the enzyme.

[0025] As a preferred embodiment of the present invention, in S4, when plant-based food excipients are used to thicken, condition, emulsify and flavor the enzymatic algae slurry, these plant-based food excipients can be prepared into a sterilized excipient liquid in advance, and the specific method includes: preparing the excipient liquid with water, and each 100L of the excipient liquid contains 0.01-0.5kg of a plant-based thickener, 0-10kg of a plant protein emulsifier, 10-40kg of a plant-based flavoring agent, and 0.005-0.01kg of a plant-based sweetener; stirring to fully dissolve or disperse the ingredients, and sterilizing to obtain a sterilized excipient liquid; using the sterilized excipient liquid to mix with the enzymatic hydrolysis slurry prepared in S3 to thicken, condition, emulsify and flavor the enzymatic hydrolysis slurry.

[0026] Preferably, the plant-based thickener is at least one of konjac flour, carrageenan, xanthan gum and gellan gum; the plant protein emulsifier is emulsified rice protein powder or emulsified soy protein isolate; the plant-based flavoring agent is at least one of concentrated coconut milk, concentrated fruit juice and concentrated fruit pulp; and the plant-based sweetener is mogroside or steviol glycoside.

[0027] Among them, the addition of plant protein emulsifiers is determined according to the protein content of the chlorella raw material and the specific addition amount. For example, when the protein content in the chlorella raw material is greater than 50%, the algae liquid can have sufficient foaming ability after protease hydrolysis, and exogenous emulsifiers are not necessary; when the protein content in the chlorella raw material does not exceed 50%, other protein emulsifiers need to be added, and generally, the higher the protein content in the chlorella raw material, the less exogenous emulsifiers need to be added. Among them, the plant-based flavoring agent preferably contains 5-20kg of concentrated coconut milk and 5-20kg of concentrated fruit juice or pulp per 100L of auxiliary liquid, so that the ice cream has a rich taste.

[0028] According to a preferred embodiment of the present invention, the sterilization method of the auxiliary material liquid is: treating at 80-100°C for 5-15 minutes, cooling to 40-60°C, and obtaining a standby sterilized auxiliary material liquid; preferably sterilizing at 100°C for 5 minutes, cooling to 50°C, and standby.

[0029] According to a preferred embodiment of the present invention, in S4, the enzymatic algae slurry prepared in S3 is mixed with the sterilized auxiliary material liquid in a volume ratio of 1:1, and homogenized at 50-60°C and 10-40MPa, or further mixed and emulsified using a shearing high-speed homogenizer to obtain an ice cream liquid. Preferably, the homogenization is performed at 50°C and 20MPa.

[0030] According to a preferred embodiment of the present invention, in S1, the chlorella used is a chlorophyll-deficient protein core globules, such as yellow protein core globules or white protein core globules. For example, the yellow protein core globules with the number CGMCC NO.40458 (see patent CN116555040B) deposited by the applicant in the General Microbiological Center of the China Microbiological Culture Collection Administration Committee can be selected; or the white protein core globules with the deposit number CGMCC NO.40787 can be selected. This type of protein core globules has a high protein content and does not contain chlorophyll, which can avoid the problem of chlorophyll browning during high temperature treatment or storage. In addition, the chlorophyll-deficient chlorella has no metallic smell and does not produce phytol / phytene with a fishy smell generated by the cleavage of the chlorophyll side chain, which effectively reduces the intensity of the fishy smell.

[0031] According to a preferred embodiment of the present invention, in S5, the ice cream liquid is firstly cooled to room temperature by a heat exchanger, and then aged at 0-8°C for 4-24h; the aged ice cream liquid is introduced into an ice cream machine at -4 to -10°C, whipped and foamed while freezing, a part of the water is frozen into ice crystals, and the volume of the liquid expands during the whipping and freezing process; finally, it is quickly frozen at a temperature of -20 to -40°C, so that the remaining water is frozen into fine ice crystals, and the ice cream is hardened and formed.

[0032] Among them, aging is a processing step for ice cream, which helps to stabilize the uniform emulsification state of the ice cream liquid. Whipping is a mechanical foaming action. During the whipping process, air is stirred into the material, and a large number of small bubbles are formed while the water is frozen. After quick freezing, the ice cream can have a soft and fluffy taste.

[0033] (III) Beneficial effects

[0034] The main technical effects of the present invention are:

[0035] 1. The present invention utilizes Chlorella to produce pure plant-based ice cream, which enriches the product types of ice cream, promotes the application scope of Chlorella in food, and provides more choices for people who are allergic or intolerant to animal-derived proteins and who prefer pure plant-based foods.

[0036] 2. The present invention incorporates the whole algae into food, and there is no need to extract and separate the components of Chlorella, which can save production costs, reduce extractant residues and pollution, fully retain various active ingredients of Chlorella except protein and starch, dietary fiber, vitamins and trace elements, etc., reduce the waste of biomass resources, enrich the flavor level of ice cream and enhance the comprehensive health care effect of the product.

[0037] 3. In order to solve the problems of tough cell wall, poor taste, and difficulty in digestion and absorption when directly eaten, the present invention first adopts a pressure of ≥80MPa for homogenization treatment, so that more than 80wt% of the solid particles in the algae liquid are ≤1μm, which is conducive to the release of the contents of the Chlorella cells and promotes the subsequent enzymatic hydrolysis, so that the nutrients in the Chlorella are easily absorbed and utilized, and the taste of the ice cream is ensured to be delicate and smooth.

[0038] 4. By sequentially performing hydrolysis treatments with amylase, saccharifying enzyme, cellulase, protease, etc., the degree of enzymatic hydrolysis at each stage is controlled, starch is fully hydrolyzed into dextrin, the raw starch taste problem caused by starch retrogradation during the shelf life is reduced, and the technical problems existing in the direct production of ice cream with Chlorella are solved. After saccharifying enzyme treatment, the self-ingredients can be used to produce sweet glucose, maltose, etc. (reducing the amount of exogenous sweeteners); through protease treatment, the protein hydrolysis degree is controlled to be no more than 30%, so that the algae liquid produces the best peptide segment of 3-8kDa, with a high foaming ability of ≥200% and a low bitterness intensity, without requiring or reducing the addition of exogenous emulsifiers, and improving the taste and soft mouthfeel of the final ice cream.

[0039] 5. Most of the protein in Chlorella is gluten, which has poor solubility in neutral foods. Poor solubility will give the ice cream an unsmooth feeling. Therefore, alkaline protease is used for proper hydrolysis during protease hydrolysis to increase the solubility of the enzymatic hydrolysis product under neutral and slightly acidic conditions, which is beneficial to improving the foaming ability of the algae liquid; the dextrin produced by starch hydrolysis and the properly hydrolyzed protein can also replace the function of oil in ice cream, making the fine structure of ice cream more substantial and maintaining smoothness (creamy taste), making up for the problem of decreased smoothness caused by low oil content in high-protein Chlorella.

[0040] 6. In addition to using high-protein chlorella as raw material, the present invention also uses plant-based thickeners, plant-based flavoring agents, plant-based protein foaming agents, plant-based sweeteners, etc., to achieve full plant-based ingredients, which is very in line with the needs of people who prefer pure plant-based foods.

[0041] 7. Chlorella with high protein content usually has low fat content, and it is easy to produce Chlorella with specific nutritional composition through artificially controlled cultivation conditions, such as low-fat and high-protein Chlorella. Ice cream prepared with this type of Chlorella can reduce the fat content (or the content is extremely low), bringing a better experience for people who pursue low calorie intake and control body fat percentage. Matters concerning the preservation of biological material samples: Deposit number: CGMCC NO.40787 Name of depository: China National Microbiological Culture Collection Administration General Microbiology Center Address of the depository: No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing Classification name: Chlorella pyrenoidosa Date of preservation: September 19, 2023. DETAILED DESCRIPTION

[0042] In order to better explain the present invention and facilitate understanding, the present invention is described in detail below through specific implementation methods.

[0043] Chlorella has advantages that general higher plants do not have. Chlorella is rich in protein, has a short growth cycle, is fast to cultivate, and is easy to artificially select algae with specific nutritional components, or accumulate certain nutritional components in cells through environmental stress. It has advantages that higher plants cannot match. Therefore, using Chlorella as a raw material to prepare ice cream can reduce fat or oil content, reduce caloric value, and make up for the problem of excessively high oil and carbohydrate content in existing ice cream.

[0044] The following is an overall scheme of the present invention, specifically providing a method for preparing pure plant-based ice cream based on cracked chlorella, comprising the following steps:

[0045] (1) Selecting Chlorella raw material: Select Chlorella with a protein content of ≥35wt%, preferably Chlorella pyrenoidosa. Chlorella pyrenoidosa has a high protein content and a low oil content. The protein content of conventionally cultured Chlorella pyrenoidosa is usually 50-60% (dry basis). After optimizing the conditions, the protein content in Chlorella pyrenoidosa can reach more than 70%.

[0046] In order to reduce the problem of chlorophyll browning during heat processing or shelf life, and to reduce the fishy smell of algae, it is preferred to use chlorophyll-deficient pyrenoid chlorella. For example, yellow pyrenoid chlorella or white pyrenoid chlorella, for example, the yellow pyrenoid chlorella with the number CGMCC NO.40458 (protein content 50-60%, starch content 20-35%) or the white pyrenoid chlorella with the deposit number CGMCC NO.40787 that the applicant has deposited in the General Microbiological Center of the China Microbiological Culture Collection Administration Committee can be selected. The yellow pyrenoid chlorella with the number CGMCC NO.40458 is recorded in the prior patent CN116555040B.

[0047] (2) High-pressure homogenization and crushing: Add water to adjust the concentration of Chlorella slurry to 100-200 g / L of cell dry weight. The pressure of the high-pressure homogenizer is higher than 80 MPa. Homogenize 1-3 times. The homogenization effect is required to achieve that the particles smaller than 1 μm in the slurry are greater than or equal to 80%.

[0048] Specifically, the appropriate homogenization pressure and number of times are determined according to the concentration of the algae liquid: when the algae slurry concentration is below 100-150g / L of cell dry weight, 100-130MPa pressure is used for homogenization 1-2 times; when the algae slurry concentration is 150-200g / L, 80-100MPa pressure is used for homogenization 2-3 times. The homogenization pressure and the number of homogenizations are appropriately adjusted according to the fluidity and crushing effect of the material, and ultimately the particles less than 1μm are greater than or equal to 80%. Further preferably, the Chlorella raw material is adjusted to an algae liquid with a concentration of 150g / L, and then a high-pressure homogenizer is used for high-pressure homogenization at 110MPa.

[0049] The principle of high-pressure homogenization is to force the algae liquid to pass through micron-sized gaps through instantaneous high pressure, and use shear force, cavitation effect and collision to break the cell wall. Therefore, limiting the concentration of algae liquid to 100-200g / L can improve the energy transfer efficiency of homogenization treatment, avoid the loss of mechanical energy caused by too low concentration, increase the collision probability of algae particles, enhance turbulent shear strength, and avoid the rapid increase of algae liquid temperature during homogenization. However, too high a concentration will form a gel-like structure, inhibit the cavitation effect, block the microchannel of the homogenization valve, and the crushing effect is poor. When the homogenization pressure is higher than 80MPa (generally 80-130MPa is used), an efficient cell crushing effect can be achieved. By adjusting the homogenization pressure and number of times, it is easy to achieve the requirement that particles below 1μm account for more than 80%, which not only ensures the full release of cell contents but also ensures the delicate taste of ice cream. Because the Chlorella cells are too small and the collision kinetic energy is low, it is difficult to achieve this crushing effect using a high-speed shearing machine and a household soy milk machine or a wall breaking machine.

[0050] (3) Sequential enzymatic hydrolysis: The algae liquid is enzymatically hydrolyzed with amylase, saccharifying enzyme, cellulase and protease in sequence to obtain enzymatically hydrolyzed algae slurry; the enzymatic hydrolysis conditions are controlled so that after the enzymatic hydrolysis is completed, the degree of starch hydrolysis reaches DE80 or above, and the foaming capacity of the algae liquid reaches more than 200%.

[0051] The principle of the above-mentioned sequential enzymatic hydrolysis is: first, enzymatic hydrolysis of starch to reduce viscosity, then adding cellulase and saccharifying enzyme to hydrolyze cellulose in the cell wall of Chlorella, increase sugar content and reduce roughness; finally, through protease hydrolysis, the protein of Chlorella is hydrolyzed to obtain peptides with high foaming ability, thereby improving the foaming ability of algae liquid. By hydrolyzing starch and crude fiber in advance, the inhibition of starch and crude fiber on the foaming performance of algae liquid can be reduced. Protease needs to be added last to avoid its degradation and inactivation of other enzymes.

[0052] Preferably, the enzymatic hydrolysis process is carried out in the following order and conditions:

[0053] ① Add 400-1000U / L α-amylase to the algae slurry, heat the algae slurry to 70-90℃ and react until the degree of starch hydrolysis reaches DE15-20.

[0054] Using α-amylase to hydrolyze starch and heating it to 70-90°C can gelatinize the starch and immediately hydrolyze it until the degree of starch hydrolysis reaches DE15-20. Since raw starch is not easy to hydrolyze, it is heated to 70-90°C to gelatinize the starch first, promote hydrolysis and quick freezing and starch degradation, and reduce the raw starch taste produced by retrogradation. Chlorella contains more starch, and α-amylase is an endo-enzyme that can cut off more starch chain fragments and produce more action sites, which is conducive to the further action of subsequent glucose enzymes (saccharifying enzymes). The saccharifying enzyme hydrolysis products provide sweetness, reducing the amount of the added plant-based sweeteners.

[0055] Further preferably, 1000 U / L of medium-temperature α-amylase is added and the algae slurry is heated to 80° C. to gelatinize the starch and immediately hydrolyze it until the degree of hydrolysis reaches DE15-20.

[0056] ② Cool down to 45-50°C and maintain the temperature, add 1000-5000U / L of cellulase and 5000-10000U / L of saccharifying enzyme until the degree of starch hydrolysis reaches DE80 or above. Preferably, cool down to 50°C and maintain the temperature, add 3500U / L of cellulase and 8000U / L of saccharifying enzyme until the degree of starch hydrolysis reaches DE80 or above. The starch initially hydrolyzed by α-amylase continues to be hydrolyzed to DE80 or above by saccharifying enzyme, thereby increasing the degree of starch hydrolysis and producing sweetness.

[0057] ③ Adjust the pH of the algae liquid to 7.5-9.0, control the temperature to 45-50°C, add 3000-8000U / L of alkaline protease, control the hydrolysis degree not to exceed 30%, or test the foaming ability of the algae slurry while hydrolyzing, until the foaming ability of the algae liquid is ≥200%. Preferably, first adjust the pH to 9.0, dynamically add 6000U / L alkaline protease with a peristaltic pump, and control the hydrolysis degree between 15-25%. At this time, most of the algae protein is hydrolyzed into 3-8kDa peptides, which have good emulsification properties, are conducive to foaming and have less bitter peptides.

[0058] The present invention uses microbial alkaline protease, which preferentially cuts the peptide bonds between hydrophobic amino acids (such as phenylalanine and leucine), just targeting the enriched area of ​​intracellular proteins of Chlorella, and increasing the solubility of the hydrolyzate in neutral and slightly acidic environments. Alkaline protease can accurately control DH at 15-25% (the optimal generation range of foaming functional peptides). The pH-stat method can be used to monitor the degree of protein hydrolysis in real time, and the precise dynamic regulation of protease hydrolysis can be achieved through the "titration-calculation-feedback" closed-loop control.

[0059] ④ Keep the temperature at 110-120℃ for 15-20s to inactivate the enzyme, and sterilize the algae solution at the same time; preferably, keep the temperature at 120℃ for 15s to inactivate the enzyme and sterilize.

[0060] Preferably, after the enzyme is inactivated, a small amount of aminopeptidase (for directional degradation of bitter peptides) and / or β-glucosidase (for directional degradation of bitter peptides) can be added to further improve the taste of ice cream. The former can reduce the content of bitter peptides, and the latter can promote the release of flavor substances, specifically hydrolyze β-1,4 glycosidic bonds, convert bitter glycosides into aglycones + glucose, and the bitterness of some aglycones is reduced after oxidation.

[0061] (4) thickening, tempering, emulsifying and flavoring the enzymatic algae slurry with plant-based food additives to obtain an ice cream liquid, wherein the solid content of the ice cream liquid is 33-40% or its viscosity at 25° C. is 3000-6000 mPa.s.

[0062] In this step, in order to make various plant-based food auxiliary materials evenly dissolved and dispersed in the ice cream liquid, the following steps can be adopted: first, these plant-based food auxiliary materials are prepared into a sterilized auxiliary liquid, specifically: water is used to prepare the auxiliary liquid, and each 100L of the auxiliary liquid contains 0.01-0.5kg of plant-based thickener, 0-10kg of plant protein emulsifier, 10-40kg of plant-based flavoring agent, and 0.005-0.01kg of plant-based sweetener; each component is fully dissolved or dispersed by stirring, sterilized at 80-100°C and treated for 5-15min, cooled to 40-60°C, and a standby sterilized auxiliary liquid is obtained. Then, the sterilized auxiliary liquid is mixed with the enzymatic slurry prepared in step (3) at a volume ratio of 1:1, and then homogenized at 50-60°C and a pressure of 10-40MPa to complete the thickening, conditioning, emulsification and seasoning of the enzymatic slurry.

[0063] Preferably, the plant-based thickener is at least one of konjac flour, carrageenan, xanthan gum and gellan gum; the plant protein emulsifier is emulsified rice protein powder or emulsified soy protein isolate; the plant-based flavoring agent is at least one of concentrated coconut milk, concentrated fruit juice and concentrated fruit pulp; and the plant-based sweetener is mogroside or steviol glycoside.

[0064] Among them, the addition of plant protein emulsifiers is determined according to the protein content of the chlorella raw material and the specific addition amount. For example, when the protein content in the chlorella raw material is greater than 50%, the algae liquid can have sufficient foaming ability after protease hydrolysis, and exogenous emulsifiers are not necessary at this time; when the protein content in the chlorella raw material does not exceed 50%, other protein emulsifiers need to be added, and generally, the higher the protein content in the chlorella raw material, the less exogenous emulsifiers need to be added. Among them, the plant-based flavoring agent preferably contains 5-20kg of concentrated coconut milk and 5-20kg of concentrated fruit juice or pulp per 100L of auxiliary liquid, so that the ice cream has a rich taste. The amount of plant-based flavoring agent added is adjusted according to the taste of the ice cream.

[0065] Preferably, every 100 L of the sterilized auxiliary material liquid contains 0.1 kg of konjac flour, 7.5 kg of emulsified soy protein isolate, 15 kg of concentrated coconut milk, 15 kg of passion fruit pulp, 0.005 kg of mogroside and 0.005 kg of stevioside.

[0066] It should be noted that no matter how the aseptic auxiliary liquid is prepared, the solid content of the final prepared ice cream liquid should not be too high or too low, or its viscosity should not be too high or too low, otherwise it may affect the whipping effect, expansion rate and viscosity of the ice cream. The solid content of the ice cream liquid should be 33-40% or its viscosity at 25°C should be 3000-6000mPa.s.

[0067] (5) Preparation of ice cream: First, the ice cream liquid is quickly cooled to room temperature using a heat exchanger, and then aged at 0-8°C for 4-24 hours; the aged ice cream liquid is introduced into an ice cream machine at -4 to -10°C, whipped and frothed while freezing, and a portion of the water is frozen into ice crystals. The volume of the liquid expands during the whipping and freezing process; finally, it is quickly frozen at a temperature of -20 to -40°C, so that the remaining water freezes into fine ice crystals, and the ice cream is hardened and formed.

[0068] Preferably, the mixture is first cooled to 25°C, and then allowed to stand at 4°C for 12 hours for aging, and then poured into an ice cream machine at -6°C while being whipped and frozen to expand the volume of the liquid, and then dispensed into ice cream barrels, and quickly frozen at -40°C to complete the hardening of the ice cream, thereby finally obtaining a chlorella ice cream product.

[0069] The present invention is described below in conjunction with specific embodiments.

[0070] Example 1

[0071] In this embodiment, yellow protein-core chlorella (preservation number CGMCCNO.40458) is used as a raw material (protein content is 55%, starch content is 20%) to prepare chlorella pure plant-based ice cream, and the steps are as follows:

[0072] (1) Place the algae pulp of Chlorella in a 300L storage tank, add drinking water to adjust the algae liquid to a cell dry weight of 150g / L, and the total volume is 200L. Use a high-pressure homogenizer to homogenize 3 times at 100MPa to obtain a broken algae pulp. Particles below 1μm account for 90% of the broken algae pulp. The broken algae pulp is sent to a 300L blending tank.

[0073] (2) In a 300L mixing tank, start stirring, add 500U / L of medium-temperature α-amylase based on the total volume of the algae slurry, heat with hot water or saturated steam at normal pressure to make the algae slurry temperature reach 80°C and maintain the temperature, take samples every 15 minutes to detect the degree of starch hydrolysis, and start cooling when it reaches DE15-20; introduce cold water into the jacket to reduce the temperature of the algae slurry to 50°C and maintain the temperature, add 3500U / L of cellulase and 5000U / L of saccharifying enzyme until the degree of starch hydrolysis reaches DE80 or above; prepare a dilute NaOH aqueous solution with food-grade sodium hydroxide, adjust the pH value of the algae slurry to 9.0, add 6000U / L of food-grade alkaline protease, stir and hydrolyze, and start taking samples every 15 minutes after 2 hours of enzymatic hydrolysis to detect the foaming ability of the algae slurry, and stop enzymolysis when the foaming power reaches 220%. At this time, the protease hydrolysis degree is 24%. The algae slurry is pumped to the high-temperature instantaneous sterilization system, heat treated at 120°C for 15s to inactivate enzymes and sterilize. The discharge temperature is controlled at 20-25°C and sent to a 500L mixing tank to wait for mixing with the sterilization auxiliary liquid.

[0074] (3) Add 0.2kg konjac flour, 30kg concentrated coconut milk, 30kg passion fruit pulp, 0.01kg mogroside and 0.01kg stevioside to a 300L mixing tank, add 150L purified water, and heat to 50°C while stirring to dissolve or disperse the ingredients. After the ingredients are completely dissolved and dispersed, add purified water to make the volume 200L. Open the jacket with normal pressure or 0.05MPa saturated steam to heat the auxiliary liquid to 100°C and keep it for 5min to obtain a sterilized auxiliary liquid. Immediately send the sterilized auxiliary liquid to a 500L mixing tank filled with enzymatic algae pulp for mixing, and adjust the liquid temperature to 50°C through the interlayer of the mixing tank with cold water. Send the liquid to a homogenizer for homogenization once under 20MPa conditions, and send it to a 500L storage tank to obtain ice cream liquid, waiting for further processing.

[0075] (4) The ice cream liquid is pumped through a heat exchanger and rapidly cooled to 20°C and sent to a 500L hot and cold cylinder. A refrigerant is passed through the interlayer to slowly cool the ice cream liquid to 4°C while stirring. Stirring is stopped and the material is allowed to stand for 12 hours for aging. The aged ice cream material is injected into an ice cream machine at -10°C and whipped while freezing, so that the moisture in the material forms ice crystals and the volume of the material expands. Finally, the material is quickly frozen at a temperature of -40°C in the ice cream machine to further freeze the moisture into fine ice crystals and harden the ice cream, thereby obtaining a Chlorella ice cream product.

[0076] Example 2

[0077] In this example, white protein core chlorella (preservation number CGMCC NO.40787) is used as the processing raw material of chlorella plant-based ice cream, with a protein content of 55% (w / w, dry matter) and a starch content of 20% (w / w, dry matter). Other processing steps are the same as those in Example 1.

[0078] Example 3

[0079] In this embodiment, yellow protein-core chlorella (preservation number CGMCCNO.40458) is used as a raw material (protein content is 40%, starch content is 30%) to prepare chlorella pure plant-based ice cream, and the steps are as follows:

[0080] (1) Place the algae slurry in a 300L storage tank, add drinking water to make the total volume of the algae slurry 300L and the algae dry matter concentration 100g / L, and homogenize twice with a high-pressure homogenizer at 120MPa to obtain broken algae slurry. Particles below 1μm account for 92% of the broken algae slurry. The broken algae slurry is sent to a 300L blending tank.

[0081] (2) In a 300L mixing tank, start stirring, add 1000U / L of medium-temperature α-amylase based on the total volume of the algae slurry, turn on hot water or normal pressure saturated steam to heat the algae slurry to 90°C and maintain the temperature, take samples every 15 minutes to detect the degree of starch hydrolysis, and start cooling when it reaches DE15-20; add cold water into the jacket to reduce the temperature of the algae slurry to 50°C and maintain the temperature, add 4000U / L of cellulase and 8000U / L of saccharifying enzyme until the degree of starch hydrolysis reaches DE80 or above; prepare a dilute NaOH aqueous solution with food-grade sodium hydroxide, adjust the pH value of the algae slurry to 9.0, add 5000U / L of food-grade alkaline protease, stir and hydrolyze, and start taking samples every 20 minutes after 2 hours of enzymatic hydrolysis to detect the foaming ability of the algae slurry, and stop enzymolysis when the foaming power is ≥200%. At this time, the protease hydrolysis degree is 21%. The algae slurry is pumped to the high-temperature instantaneous sterilization system, heat treated at 110℃ for 20s to inactivate enzymes and sterilize. The discharge temperature is controlled at 20-25℃ and sent to an 800L mixing tank to wait for mixing with the sterilization auxiliary liquid.

[0082] (3) Add 0.6kg gellan gum, 20kg emulsified rice protein powder, 20kg concentrated coconut milk, 30kg passion fruit pulp, 0.03kg mogroside and 0.03kg stevioside to a 300L mixing tank, add 250L purified water, and heat to 50°C while stirring to dissolve or disperse the ingredients. After the ingredients are completely dissolved and dispersed, add purified water to make the volume 300L. Open the jacket with normal pressure or 0.05MPa saturated steam to heat the auxiliary material liquid to 100°C and keep it for 5min to obtain a sterilized auxiliary material liquid. Immediately send the sterilized auxiliary material liquid to the 800L mixing tank filled with enzymatic algae pulp for mixing, and adjust the temperature of the material liquid to 50°C through the interlayer of the mixing tank. Send the material liquid to the homogenizer for homogenization once under 20MPa conditions, and send it to the 800L storage tank to obtain the ice cream material liquid, waiting for further processing.

[0083] (4) The ice cream liquid is pumped through a heat exchanger and rapidly cooled to 20°C and sent to an 800L hot and cold cylinder. A refrigerant is passed through the interlayer to slowly cool the ice cream liquid to 4°C while stirring. Stirring is stopped and the material is allowed to stand for 12 hours for aging. The aged ice cream material is injected into an ice cream machine at -10°C and whipped while freezing, so that the moisture in the material forms ice crystals and the volume of the material expands. Finally, the material is quickly frozen at -40°C in the ice cream machine to further freeze the moisture into fine ice crystals and harden the ice cream, thereby obtaining a Chlorella ice cream product.

[0084] Example 4

[0085] This example is based on Example 3, and 200 U / L of aminopeptidase and 300 U / L of β-glucosidase are added to the sterilized algae slurry. The other processing steps are the same as those in Example 3.

[0086] Comparative Example 1

[0087] This comparative example is based on Example 1, except that the homogenization and cell wall breaking process is omitted, and the amylase and protease are enzymolyzed for 3 hours respectively.

[0088] Comparative Example 2

[0089] This comparative example is based on Example 1, but the enzymatic hydrolysis process of amylase and saccharifying enzyme is omitted.

[0090] Comparative Example 3

[0091] In this comparative example, based on Example 1, the amount of alkaline protease added was increased to 12000 U / L, and the degree of protease hydrolysis was increased to 36%. At this time, the foaming capacity of the algae liquid was 130%.

[0092] Comparative Example 4

[0093] In this comparative example, based on Example 1, the addition amount of alkaline protease was reduced to 400 U / L, and the degree of protease hydrolysis was reduced to 10%. At this time, the foaming ability of the algae liquid was 165%.

[0094] The quality of the chlorella ice cream in the above embodiments is shown in Table 1:

[0095] Table 1 Quality indicators of chlorella plant-based ice cream with different raw materials and processing technology

[0096] Group Expansion rate % Melting rate % Viscosity Smoothness Meltiness Graininess Example 1 80.4 7.9 8.8 8.2 7.0 8.0 Example 2 78.9 9.5 7.5 7.9 7.5 8.3 Example 3 71.2 8.5 7.8 7.2 6.0 8.1 Example 4 80.1 8.2 8.9 8.3 7.6 8.5 Comparative Example 1 28.5 15.8 6.7 4.5 6.5 4.6 Comparative Example 2 62.4 20.5 6.5 4.3 3.6 4.1 Comparative Example 3 43.6 8.5 7.5 5.8 7.7 8.0 Comparative Example 4 47.8 11.4 7.0 6.3 6.2 7.2

[0097] Test method:

[0098] (1) Ice cream expansion rate: Take a certain volume of pre-freezing ice cream slurry and an equal volume of finished ice cream, weigh them respectively, and calculate the ice cream expansion rate using formula (a):

[0099]

[0100] (2) Ice cream melting rate: Ice cream that had been hardened at -40 °C for 24 h was taken out of the mold, and a certain mass of ice cream product was placed on a 1 mm × 1 mm sieve and melted in an oven at 25 °C. The time when the first drop of ice cream dripped was recorded, denoted as M0. After 150 min, the mass of ice cream dripping was recorded, i.e., the mass of ice cream melted. The ice cream melting rate was calculated using formula (b):

[0101]

[0102] (3) Sensory evaluation: The ice cream was placed in a -18°C freezer for 24 h and then taken out. Ten evaluators who were familiar with ice cream products and had received sensory training were invited to score the ice cream according to Table 2. The average score was calculated after removing the highest and lowest scores, and finally the total sensory score was calculated.

[0103] Table 2 Sensory evaluation criteria for ice cream

[0104]

[0105] As shown in Table 1, when comparing Comparative Example 1 with Example 1, Comparative Example 1 omits the high-pressure homogenizer treatment, the chlorella cells are not broken, and the protein and starch cannot be released. Although the algae pulp has been enzymatically hydrolyzed, the protein has not been effectively degraded, and an effective foaming effect cannot be produced. The foaming power of the algae pulp is poor, and the expansion rate of the ice cream is poor; on the other hand, due to the poor foaming property, the cells are not broken, so that the ice cream has a granular feel, and the smoothness and viscosity are poor. Although the cells have been broken in Comparative Example 2, the enzymatic hydrolysis of amylase and saccharifying enzyme is omitted, and the starch of chlorella is not hydrolyzed. The ice cream has a significant raw starch granular feel after being placed in the refrigerator for 24 hours, and the overall viscosity is significantly reduced. The degree of proteolysis of Comparative Example 3 is excessive, most of the peptides are too short, and the molecular weight is less than the optimal foaming peptide (3-8kDa), the whipping effect is not good, the expansion of the ice cream is not high, and the softness and smoothness decrease. In Comparative Example 4, the degree of proteolysis is insufficient, most of the peptides are too long, the molecular weight is greater than the optimal foaming peptide (3-8 kDa), the molecular scale interface activity is insufficient and the mesostructure regulation is ineffective, the whipping effect and expansion degree of the ice cream liquid are insufficient, and the meltability and smoothness in the mouth are insufficient.

[0106] It can be seen from Example 1 and Example 2 that as long as the protein content and starch content of Chlorella pyrenoidosa are similar, ice cream products with good and similar indicators can be obtained using the same process, indicating that the ice cream products prepared by the preparation method of the present invention have good consistency.

[0107] Comparison between Example 1 and Example 3 shows that replacing konjac flour with gellan gum as a thickener can also obtain good ice cream quality, but the protein content of protein core chlorella in Example 3 is low, so it is necessary to use an exogenous emulsifier (emulsified rice protein powder) as an enhanced foaming agent, which can also make the ice cream obtain a higher expansion rate and obtain a good ice cream variety. However, in Example 1, the dry matter content of algae slurry is relatively high, that is, when it is 150g / L, compared with Example 3, the former ice cream expansion force and viscosity are relatively improved, but the quality of the ice cream of the two examples is at a good level.

[0108] The amount of amylase and protease added and the hydrolysis time are mainly determined by the degree of hydrolysis. Only when the starch hydrolysis reaches a high degree of hydrolysis can the starch be converted into sugar, oligosaccharide or small molecular dextrin, so as to avoid the problem of starch retrogradation in a frozen environment, increase viscosity and sweetness, and reduce the addition of the plant-based sweetener; the hydrolysis of protein is based on the principle of achieving foaming ability. Only an appropriate degree of protein hydrolysis can improve water solubility and emulsification ability. Too high a degree of hydrolysis (greater than 30%) or insufficient hydrolysis (less than 10%) will reduce the emulsification and foaming ability of the protein. Insufficient protein hydrolysis also affects solubility and the smoothness of ice cream. When the algae slurry reaches 200% of its foaming ability, a good ice cream whipping effect and expansion rate can be obtained.

[0109] It can be seen from the implementation effects of Examples 1-3 that by using cracked chlorella as raw material, selecting all plant-based ingredients, using plant-based sweeteners extracted from plants, without adding carbohydrates such as sucrose, and without adding oil, good ice cream production can be achieved, and a fully plant-based, low-fat, low-calorie, nutritious and healthy ice cream product with a smooth taste can be produced.

[0110] The following are the nutritional parameters of the chlorella ice cream of Examples 1 and 3 and commercially available ice cream as shown in Table 3:

[0111] Table 3 Comparison of nutritional indicators of chlorella plant-based ice cream and commercial ice cream

[0112]

[0113] In summary, the present invention provides a pure plant-based ice cream product using cracked chlorella as a raw material, which is high in protein and low in energy, can be used as a substitute for traditional ice cream, and provides an ideal cold drink for people who are allergic / intolerance to milk, pursue low calorie intake, control body fat rate and insist on plant-based food.

[0114] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing pure plant-based ice cream based on cracked chlorella, characterized in that: The steps include: S1. Using Chlorella with a protein content of ≥35wt% as raw material; S2, adjusting the chlorella raw material to an algae liquid with a concentration of 100-200 g / L, and treating it with a high-pressure homogenizer to make more than 80 wt % of the solid particles in the algae liquid ≤ 1 μm; S3, using amylase, saccharifying enzyme, cellulase and protease to enzymatically hydrolyze the algae liquid in sequence to obtain enzymatically hydrolyzed algae slurry; the degree of starch hydrolysis reaches DE80 or above through enzymatic hydrolysis, and the foaming ability of the algae liquid reaches more than 200%; S4, thickening, tempering, emulsifying and flavoring the enzymatic algae slurry with plant-based food auxiliary materials to obtain an ice cream liquid, wherein the solid content of the ice cream liquid is 33-40% or the viscosity at 25° C. is 3000-6000 mPa.s; S5. Use an ice cream machine to freeze the ice cream liquid into ice cream.

2. The preparation method according to claim 1, characterized in that: In S3, the enzymatic hydrolysis process is as follows: S31, adding 400-1000U / L α-amylase to the algae slurry, heating the algae slurry to 70-90°C for reaction, until the degree of starch hydrolysis detected reaches DE15-20; S32, cool down to 45-50°C and maintain the temperature, add 1000-5000U / L of cellulase and 5000-10000U / L of saccharifying enzyme until the degree of starch hydrolysis reaches DE80 or above; S33, adjusting the pH of the algae liquid to 7.5-9.0, controlling the temperature to 45-50°C, adding 3000-8000U / L of alkaline protease, controlling the hydrolysis degree not to exceed 30% or testing the foaming ability of the algae slurry while hydrolyzing until the foaming ability of the algae liquid is ≥200%; S34. Keep warm at 110-120℃ for 15-20s to inactivate the enzyme.

3. The preparation method according to claim 2, characterized in that: In S33, the pH-stat method is used for real-time monitoring to control the degree of hydrolysis of the protein to be 15-25%.

4. The preparation method according to claim 1, characterized in that: S4 includes: First, prepare an auxiliary liquid, which is prepared from water, and each 100L of the auxiliary liquid contains 0.01-0.5kg of a plant-based thickener, 0-10kg of a plant protein emulsifier, 10-40kg of a plant-based flavoring agent, and 0.005-0.01kg of a plant-based sweetener; each component is fully dissolved or dispersed by stirring, and after sterilization, a sterilized auxiliary liquid is obtained; the sterilized auxiliary liquid is used to mix with the enzymatic hydrolysis slurry prepared in S3 to thicken, condition, emulsify and flavor the enzymatic hydrolysis slurry.

5. The preparation method according to claim 4, characterized in that: The plant-based thickener is selected from at least one of konjac flour, carrageenan, xanthan gum and gellan gum; The plant-based flavoring agent is concentrated coconut milk or concentrated fruit juice / pulp; The plant-based sweetener is mogroside or steviol glycoside.

6. The preparation method according to claim 4, characterized in that: The vegetable protein emulsifier is at least one of emulsified rice protein powder and emulsified soy protein isolate; The amount of vegetable protein emulsifier added is determined according to the protein content in the chlorella raw material. When the protein content of the chlorella raw material is ≥50%, the amount of vegetable protein emulsifier added is zero; When the protein content of the chlorella raw material is between 35% and 50%, as the protein content of the chlorella raw material is higher, the amount of the exogenous plant protein emulsifier added is less.

7. The preparation method according to claim 4, characterized in that: The sterilization conditions are 80-100℃ for 5-15min, and then cooled to 40-60℃ for use.

8. The preparation method according to claim 4, characterized in that: In S4, the enzymatic algae slurry prepared in S3 is mixed with the sterilized auxiliary material liquid in a volume ratio of 1:1, and homogenized at 50-60° C. and 10-40 MPa, or further mixed and emulsified using a shear-type high-speed homogenizer to obtain an ice cream liquid.

9. The preparation method according to claim 1, characterized in that: In S5, the ice cream liquid is firstly cooled to room temperature by a heat exchanger, and then allowed to stand at 0-8°C for 4-24 hours for aging; The aged ice cream liquid is introduced into an ice cream machine at -4 to -10℃, whipped and frothed while freezing. Part of the water is frozen into ice crystals, and the volume of the liquid expands during the whipping and freezing process; finally, it is quickly frozen at a temperature of -20 to -40℃, so that the remaining water freezes into tiny ice crystals, and the ice cream is hardened and formed.

10. A pure plant-based ice cream based on cracked chlorella, characterized in that: The method is prepared by the method according to any one of claims 1 to 9.

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