阅读说明：本技术 一种活菌型酸奶块及其制备方法 (Live bacterium type yogurt block and preparation method thereof ) 是由 李伟 于 2020-12-28 设计创作，主要内容包括：本发明公开了一种活菌型酸奶块及其制备方法,其包括以下步骤：预热原料乳,在原料乳搅拌时加入稳定剂、益生菌增殖剂、甜味剂,得乳液；将乳液经均质、杀菌、冷却处理后,加入发酵剂发酵,得发酵基液；待发酵基液至发酵终点,结束发酵,翻缸、打冷,得酸奶基液；将酸奶基液中加入果粒、冻干保护剂,搅拌均匀,得酸奶；将酸奶平铺于无菌模具中,放入冻库冷冻,得冷冻酸奶；将冷冻酸奶冷冻完全后放入冻干机中,得冻干酸奶块；冻干酸奶块冻干结束,将其密封于无菌袋中,抽真空,即得所述活菌型酸奶块。本发明的优点是采用纯益生菌发酵和冷冻干燥技术制备出活菌型酸奶块,并采用添加增殖剂和冻干保护剂,保证所得产品中益生菌数量和益生菌活性。(The invention discloses a live bacterium type yogurt block and a preparation method thereof, wherein the preparation method comprises the following steps: preheating raw milk, and adding a stabilizer, a probiotic proliferation agent and a sweetening agent while stirring the raw milk to obtain emulsion; homogenizing, sterilizing, cooling, adding starter, and fermenting to obtain fermentation base liquid; after the fermentation base liquid reaches the fermentation end point, ending the fermentation, turning over the cylinder, and cooling to obtain the yoghourt base liquid; adding the fruit particles and the freeze-drying protective agent into the yoghourt base solution, and uniformly stirring to obtain yoghourt; flatly paving the yoghourt in an aseptic mold, and putting the yoghourt into a freezer for freezing to obtain frozen yoghourt; completely freezing the frozen yogurt, and putting the frozen yogurt into a freeze dryer to obtain frozen yogurt blocks; and (5) after the freeze-drying of the freeze-dried yogurt block is finished, sealing the freeze-dried yogurt block in a sterile bag, and vacuumizing to obtain the viable bacteria type yogurt block. The invention has the advantages that the pure probiotic fermentation and freeze-drying technology is adopted to prepare the live bacteria type yoghurt block, and the proliferation agent and the freeze-drying protective agent are added to ensure the quantity and the activity of the probiotics in the obtained product.)

1. A preparation method of a live bacteria type yogurt block is characterized in that the raw materials of the live bacteria type yogurt block comprise: 6-8% of sweetening agent, 0.6-1% of albumen powder, 0.07-0.16% of stabilizing agent, 0.02-0.08% of probiotic proliferation agent, 0.06-0.12% of freeze-drying protective agent, 6-12% of fruit particles, 0.01-0.1% of fermenting agent and the balance of raw milk, wherein the percentages are mass percentages of the total mass of the raw materials; the preparation method comprises the following steps:

(1) preheating raw milk, and adding a stabilizer, a probiotic proliferation agent and a sweetening agent while stirring the raw milk to obtain emulsion;

(2) homogenizing, sterilizing and cooling the emulsion obtained in the step (1), and adding a leavening agent for fermentation to obtain a fermentation base liquid;

(3) after the fermentation base liquid in the step (2) is fermented to the fermentation end point, ending the fermentation, turning over the cylinder, and cooling to obtain the yoghourt base liquid;

(4) adding the fruit particles and the freeze-drying protective agent into the yoghourt base liquid obtained in the step (3), and uniformly stirring to obtain yoghourt;

(5) flatly paving the yoghourt obtained in the step (4) in a sterile mould, and putting the yoghourt into a freezer for freezing to obtain frozen yoghourt;

(6) completely freezing the frozen yogurt obtained in the step (5), and putting the frozen yogurt into a freeze dryer to obtain a frozen yogurt block;

(7) and (4) after the freeze-dried yogurt blocks obtained in the step (6) are freeze-dried, sealing the freeze-dried yogurt blocks in a sterile bag, and vacuumizing to obtain the viable bacteria type yogurt blocks.

2. The method for preparing viable bacteria type yogurt block according to claim 1, wherein in the step (1), the raw milk is preheated to 50-60 ℃ and stirred for 15-25 min.

3. The method of claim 1, wherein the stabilizer is at least one selected from carrageenan, carboxymethyl cellulose and pectin in step (1).

4. The method for preparing a viable bacteria-type yogurt block according to claim 1, wherein in the step (1), the probiotic proliferation agent is one or more of solid malt extract and enzymatic oat flour.

5. The method of claim 1, wherein the starter culture in step (2) is two or more of Lactobacillus rhamnosus, Bifidobacterium lactis, and Lactobacillus casei.

6. The method of claim 1, wherein the acidity of the fermentation end point is 70 to 80 ° T and the temperature after cooling is 15 to 25 ℃ in the step (3).

7. The method for preparing viable bacteria type yogurt block according to claim 1, wherein in the step (4), the fruit grains are one or more of blueberry fruit grains, grape fruit grains, grapefruit fruit grains and pineapple fruit grains.

8. The method for preparing a viable bacteria-type yogurt block of claim 1, wherein in the step (4), the lyoprotectant is one or more of mannitol and ascorbic acid.

9. The method for preparing viable bacteria type yogurt block according to claim 1, wherein in step (6), the water content of the frozen yogurt is dried by sublimation in a freeze dryer with a required vacuum degree of 1-5Pa for 24-36 h.

10. A viable bacteria type yogurt block characterized in that it is directly prepared by the method for preparing a viable bacteria type yogurt block according to any one of claims 1 to 9.

Technical Field

The invention relates to the technical field of fermented milk, in particular to a live bacterium type yogurt block and a preparation method thereof.

Background

Dairy products have a long history and occupy an important position in the modern food industry, wherein fermented milk is the most important part of the dairy products, and the fermented dairy products in the market have various types, serious product homogenization and strong competition; in order to obtain larger market share, related dairy product enterprises continuously innovate fermentation products, and the main innovative ideas are focused in the directions of functionalization, zero-eating, high-end and the like.

In the modern fast-paced life, the zero-eating of the yoghourt is one of the future trends, the solid yoghourt prepared by the existing freeze drying technology meets the characteristics of snack, and has the advantages of long storage time, normal room-temperature storage and 12-18 months of shelf life; the transportation, the sale and the carrying are convenient; interesting, various eating modes and the like.

The supplement of probiotics is not only directly eating probiotic powder or liquid, but also taking yoghourt as a carrier is the most common way for supplementing probiotics at present; the yogurt in the market is divided into low-temperature yogurt and normal-temperature yogurt, wherein only the low-temperature yogurt is beneficial to probiotics, and the normal-temperature yogurt after pasteurization is free of live probiotics, but the low-temperature yogurt has the main defects of small quantity of live bacteria, short shelf life, low-temperature storage requirement and high cost.

The existing pure probiotic fermentation and freeze drying process is combined, the defects of the existing low-temperature yoghourt and normal-temperature yoghourt can be overcome, but the main technical difficulties are long fermentation time, unpleasant yoghourt flavor after fermentation and poor yoghourt texture.

Disclosure of Invention

In order to solve the problems, the invention aims to disclose a live-bacterium type yogurt block and a preparation method thereof, namely, pure probiotics are adopted for fermentation in the fermentation process, and a proper proliferation agent is added to shorten the fermentation time and improve the number of probiotics; in the whole process of freeze drying, the temperature of the yoghourt is always kept at a low level, a proper freeze-drying protective agent is added into the yoghourt, so that the loss of probiotics in the yoghourt is little, and the final product is crisp in texture and good in rehydration property through a freeze-drying technology, so that various eating modes of consumers are met.

The invention is realized by the following technical scheme:

specifically, on the one hand, a preparation method of the live bacterial type yogurt block is provided, and the raw materials of the live bacterial type yogurt block comprise: 6-8% of sweetening agent, 0.6-1% of albumen powder, 0.07-0.16% of stabilizing agent, 0.02-0.08% of probiotic proliferation agent, 0.06-0.12% of freeze-drying protective agent, 6-12% of fruit particles, 0.01-0.1% of fermenting agent and the balance of raw milk, wherein the percentages are mass percentages of the total mass of the raw materials; the preparation method comprises the following steps:

(1) preheating raw milk, and adding a stabilizer, a probiotic proliferation agent and a sweetening agent while stirring the raw milk to obtain emulsion;

(2) homogenizing, sterilizing and cooling the emulsion obtained in the step (1), and adding a leavening agent for fermentation to obtain a fermentation base liquid;

(3) after the fermentation base liquid in the step (2) is fermented to the fermentation end point, ending the fermentation, turning over the cylinder, and cooling to obtain the yoghourt base liquid;

(4) adding the fruit particles and the freeze-drying protective agent into the yoghourt base liquid obtained in the step (3), and uniformly stirring to obtain yoghourt;

(5) flatly paving the yoghourt obtained in the step (4) in a sterile mould, and putting the yoghourt into a freezer for freezing to obtain frozen yoghourt;

(6) completely freezing the frozen yogurt obtained in the step (5), and putting the frozen yogurt into a freeze dryer to obtain a frozen yogurt block;

(7) and (4) after the freeze-dried yogurt blocks obtained in the step (6) are freeze-dried, sealing the freeze-dried yogurt blocks in a sterile bag, and vacuumizing to obtain the viable bacteria type yogurt blocks.

By the technical scheme, the raw milk is raw milk which meets the national standard of China; the sweetener is sucrose; the protein powder is milk protein powder, and the protein content is more than or equal to 80 percent; in the whole process of freeze drying, the temperature of the yoghourt is always kept at a low level, meanwhile, a proper freeze-drying protective agent is added into the yoghourt to ensure that the probiotics in the yoghourt are less lost, and the final product is crisp in texture and good in rehydration property through a freeze-drying technology, so that various eating modes of consumers are met.

Specifically, in the step (2), the homogenizing temperature is 60-65 ℃, and the homogenizing pressure is 18-20 Mpa, wherein the primary homogenizing pressure is 14-16 Mpa, and the secondary homogenizing pressure is 4-6 Mpa; the sterilization mode in the step (2) adopts tubular sterilization, the sterilization temperature is 90-95 ℃, and the sterilization time is 5-10 min; cooling to the temperature of 37-42 ℃ in the step (2); in the step (5), the temperature of the warehouse is between 40 ℃ below zero and 35 ℃, and the pre-freezing time is 6 to 10 hours; the sterile bag in the step (7) is a sterile bag which has good sealing performance and can be vacuumized.

Further, in the step (1), the preheating temperature of the raw milk is 50-60 ℃, and the stirring time is 15-25 min.

Through above-mentioned technical scheme, compare with prior art, the churning time further shortens, and raw materials dispersion is more even, and it is more abundant to change the material.

Further, in the step (1), the stabilizer is two or more of carrageenan, carboxymethyl cellulose and pectin.

According to the technical scheme, the carrageenan, the carboxymethyl cellulose, the pectin and the yoghourt can provide a certain supporting effect after being mixed and dried, and the prepared yoghourt block is crisp in texture and good in formability.

Further, in the step (1), the probiotic proliferation agent is one or more than two of solid malt extract and enzymolysis oat flour.

By the technical scheme, the fermentation speed of single or pure probiotics is low, the fermentation time of the yoghourt is greatly reduced after the proliferation agent is added, and the number of probiotics is greatly increased.

Further, in the step (2), the leavening agent is two or more of lactobacillus rhamnosus, bifidobacterium lactis and lactobacillus casei.

Through the technical scheme, the obtained yoghurt block is a pure probiotic yoghurt block, a carrier form of probiotics is added, and the demand of people on the probiotics is met.

Further, in the step (3), the acidity of the fermentation end point is 70-80 DEG T, and the temperature after cooling is 15-25 ℃.

By adopting the technical scheme, the obtained yoghourt block has proper sour and sweet taste, and the temporary storage time of the yoghourt is long, thereby being beneficial to the actual production of factories.

Further, in the step (4), the fruit grains are one or more of blueberry fruit grains, grape fruit grains, grapefruit fruit grains and pineapple fruit grains.

By adopting the technical scheme, the bad fermentation flavor of the pure probiotic is covered, and the solid content, the interestingness and the multi-taste selection of the yogurt block are increased.

Further, in the step (4), the lyoprotectant is one or more than two of mannitol and ascorbic acid.

Through the technical scheme, the adopted freeze-drying protective agent can be used in food, the death of probiotics is reduced to a certain extent by adding the freeze-drying protective agent, and the number of live probiotics in a final product is ensured.

Further, in the step (6), the water content of the frozen yoghourt is subjected to sublimation drying in a freeze dryer, the required vacuum degree is 1-5Pa, and the time is 24-36 h.

Through the technical scheme, the freeze-drying time can be reduced by maintaining the lower vacuum degree in the freeze-drying process, and the freeze-drying time needs to be long enough from the viewpoints of ensuring the dryness of the final product and saving energy.

On the other hand, the invention also provides a live bacterial type yoghurt block which is directly prepared by the preparation method of the live bacterial type yoghurt block.

Compared with the prior art, the invention has the following advantages: the proliferation of the probiotics in the yoghourt is greatly promoted by adding a proper proliferation agent, the fermentation time is shortened, and the number of the probiotics is increased; the right amount of the freeze-drying protective agent is added, so that the death of the probiotics in the freeze drying process can be protected to a certain extent, and the quantity of the probiotics in the finished product is ensured; meanwhile, the shelf life of the yogurt blocks prepared by adopting the freeze drying process is obviously longer than that of the existing normal-temperature yogurt, and the shelf life is as long as 12-18 months; in addition, the prepared yoghourt block is easy to carry, has strong interest and is suitable for more eating scenes.

Detailed Description

The invention is further illustrated by the following examples, which are not intended to limit the scope of the invention. The experimental methods without specifying specific conditions in the following examples were selected according to the conventional methods and conditions, or according to the commercial instructions.

The starting materials and reagents used in the following examples were all commercially available.

Example 1

A preparation method of a live bacteria type yogurt block comprises the following raw materials: 87.24% of raw milk, 6% of cane sugar, 0.6% of milk protein powder, 0.07% of carrageenan and carboxymethyl cellulose (the addition amount is 2:1), 0.02% of solid malt extract, 0.06% of mannitol, 6% of blueberry fruit grains and grape fruit grains (the addition amount is 1:1), and 0.01% of lactobacillus rhamnosus and bifidobacterium lactis (the addition amount is 9:1), wherein the percentages are mass percentages of the total mass of the raw materials; the preparation method comprises the following steps:

(1) preheating raw milk to 50 ℃, adding milk protein powder, carrageenan, carboxymethyl cellulose and solid malt extract while stirring the raw milk, and stirring for 25min to obtain emulsion;

(2) preheating the emulsion obtained in the step (1) to 60 ℃, homogenizing under the condition of the homogenizing pressure of 18Mpa (the first-stage homogenizing pressure is 14Mpa, and the second-stage homogenizing pressure is 4Mpa), sterilizing in a tubular manner, cooling to 37 ℃, and adding lactobacillus rhamnosus: fermenting with the addition amount of bifidobacterium lactis of 9:1 to obtain a fermentation base solution; wherein the sterilization temperature is 90 ℃ and the time is 10 min;

(3) after the fermentation base liquid in the step (2) is fermented until the acidity is 70 DEG T, ending the fermentation, turning over the cylinder, and cooling to 15 ℃ to obtain the yoghourt base liquid;

(4) adding blueberry fruit particles, grape fruit particles and mannitol into the yoghourt base solution obtained in the step (3), and uniformly stirring to obtain yoghourt;

(5) flatly paving the yoghourt obtained in the step (4) in a sterile mould, and putting the yoghourt into a freezer with the temperature of-40 ℃ for freezing for 6 hours to obtain frozen yoghourt;

(6) completely freezing the frozen yogurt obtained in the step (5), and then putting the frozen yogurt into a freeze dryer with the vacuum degree of 1pa for drying for 24 hours to obtain frozen yogurt blocks;

(7) and (4) after the freeze-dried yogurt blocks obtained in the step (6) are freeze-dried, sealing the freeze-dried yogurt blocks in a sterile bag, and vacuumizing to obtain the viable bacteria type yogurt blocks.

Through the embodiment, the viable bacteria type yogurt block prepared by the preparation method has the advantages of high probiotic content, long shelf life, crisp taste and good rehydration property.

Example 2

A preparation method of a live bacteria type yogurt block comprises the following raw materials: 78.54 percent of raw milk, 8 percent of cane sugar, 1 percent of milk protein powder, 0.16 percent of carrageenan and pectin (the addition amount is 1:1), 0.08 percent of enzymolysis oat flour, 0.12 percent of ascorbic acid, 12 percent of grapefruit fruit grains and pineapple fruit grains (the addition amount is 1:1), and 0.1 percent of lactobacillus rhamnosus and lactobacillus casei (the addition amount is 1:1), wherein the percentages are mass percentages of the total mass of the raw materials; the preparation method comprises the following steps:

(1) preheating raw milk to 60 ℃, adding milk protein powder, carrageenan, pectin and enzymolysis oat powder while stirring the raw milk, and stirring for 15min to obtain emulsion;

(2) preheating the emulsion obtained in the step (1) to 65 ℃, homogenizing under the condition of homogenizing pressure of 20Mpa (primary homogenizing pressure of 14Mpa and secondary homogenizing pressure of 6Mpa), sterilizing in a tubular manner, cooling to 42 ℃, and adding lactobacillus rhamnosus: fermenting the lactobacillus casei in an addition amount of 1:1 to obtain a fermentation base solution; wherein the sterilization temperature is 95 ℃ and the sterilization time is 5 min;

(3) after the fermentation base liquid in the step (2) is fermented until the acidity is 80 DEG T, ending the fermentation, turning over the cylinder, and cooling to 25 ℃ to obtain the yoghourt base liquid;

(4) adding grapefruit fruit particles, pineapple fruit particles and ascorbic acid into the yogurt base liquid obtained in the step (3), and uniformly stirring to obtain yogurt;

(5) flatly paving the yoghourt obtained in the step (4) in a sterile mould, and putting the yoghourt into a freezer with the temperature of-35 ℃ for freezing for 10 hours to obtain frozen yoghourt;

(6) completely freezing the frozen yogurt obtained in the step (5), and then putting the frozen yogurt into a freeze dryer with the vacuum degree of 5pa for drying for 36 hours to obtain frozen yogurt blocks;

(7) and (4) after the freeze-dried yogurt blocks obtained in the step (6) are freeze-dried, sealing the freeze-dried yogurt blocks in a sterile bag, and vacuumizing to obtain the viable bacteria type yogurt blocks.

Through the embodiment, the viable bacteria type yogurt block prepared by the preparation method has the advantages of high probiotic content, long shelf life, crisp taste and good rehydration property.

Example 3

A preparation method of a live bacteria type yogurt block comprises the following raw materials: 82.89% of raw milk, 7% of cane sugar, 0.8% of milk protein powder, 0.12% of pectin, carrageenan and carboxymethyl cellulose (the adding amount is 2: 2:1), 0.05% of solid malt extract and enzymolysis oat powder (the adding amount is 1:1), 0.09% of mannitol and ascorbic acid (the adding amount is 1:1), 9% of blueberry fruit grains, grape fruit grains, grapefruit fruit grains and pineapple fruit grains (the adding amount is 1:1:1), and 0.05% of lactobacillus rhamnosus, bifidobacterium lactis and lactobacillus casei (the adding amount is 10:1:1), wherein the percentages are mass percentages of the total mass of the raw materials; the preparation method comprises the following steps:

(1) preheating raw milk to 55 ℃, adding pectin, carrageenan, carboxymethyl cellulose, solid malt extract and enzymolysis oat flour while stirring the raw milk, and stirring for 20min to obtain emulsion;

(2) preheating the emulsion obtained in the step (1) to 63 ℃, homogenizing under the homogenizing pressure of 19Mpa (the first-stage homogenizing pressure is 16Mpa, and the second-stage homogenizing pressure is 3Mpa), sterilizing in a tubular manner, cooling to 40 ℃, and adding lactobacillus rhamnosus and bifidobacterium lactis: fermenting the lactobacillus casei in an addition amount of 10:1:1 to obtain a fermentation base solution; wherein the sterilization temperature is 93 ℃ and the sterilization time is 8 min;

(3) after the fermentation base liquid in the step (2) is fermented until the acidity is 75 DEG T, ending the fermentation, turning over the cylinder, and cooling to 20 ℃ to obtain the yoghourt base liquid;

(4) adding blueberry fruit particles, grape fruit particles, grapefruit fruit particles, pineapple fruit particles, mannitol and ascorbic acid into the yoghourt base solution obtained in the step (3), and uniformly stirring to obtain yoghourt;

(5) flatly paving the yoghourt obtained in the step (4) in a sterile mould, and putting the yoghourt into a freezer at the temperature of-38 ℃ for freezing for 8 hours to obtain frozen yoghourt;

(6) completely freezing the frozen yogurt obtained in the step (5), and then putting the frozen yogurt into a freeze dryer with the vacuum degree of 3pa for drying for 30h to obtain frozen yogurt blocks;

(7) and (4) after the freeze-dried yogurt blocks obtained in the step (6) are freeze-dried, sealing the freeze-dried yogurt blocks in a sterile bag, and vacuumizing to obtain the viable bacteria type yogurt blocks.

Through the embodiment, the viable bacteria type yogurt block prepared by the preparation method has the advantages of high probiotic content, long shelf life, crisp taste and good rehydration property.

Comparative example 1

A preparation method of a live bacteria type yogurt block comprises the following raw materials: 82.942% of raw milk, 7% of white granulated sugar, 0.8% of milk protein powder, 0.048% of carrageenan, 0.024% of carboxymethyl cellulose, 0.048% of pectin, 0.045% of mannitol, 0.045% of ascorbic acid, 2.25% of blueberry fruit granules, 2.25% of grape fruit granules, 2.25% of grapefruit fruit granules, 2.25% of pineapple fruit granules, 0.04% of lactobacillus rhamnosus, 0.004% of bifidobacterium lactis and 0.004% of lactobacillus casei, wherein the percentages are mass percentages of the total mass of the raw materials; the preparation method comprises the following steps:

(1) preheating raw milk to 55 deg.C, adding pectin, carrageenan and carboxymethyl cellulose while stirring raw milk, and stirring for 20min to obtain emulsion;

(2) preheating the emulsion obtained in the step (1) to 63 ℃, homogenizing under the homogenizing pressure of 19Mpa (the first-stage homogenizing pressure is 16Mpa, and the second-stage homogenizing pressure is 3Mpa), sterilizing in a tubular manner, cooling to 40 ℃, and adding lactobacillus rhamnosus and bifidobacterium lactis: fermenting the lactobacillus casei in an addition amount of 10:1:1 to obtain a fermentation base solution; wherein the sterilization temperature is 93 ℃ and the sterilization time is 8 min;

(3) after the fermentation base liquid in the step (2) is fermented until the acidity is 72 DEG T, ending the fermentation, turning over the cylinder, and cooling to 20 ℃ to obtain the yoghourt base liquid;

(4) adding blueberry fruit particles, grape fruit particles, grapefruit fruit particles, pineapple fruit particles, mannitol and ascorbic acid into the yoghourt base solution obtained in the step (3), and uniformly stirring to obtain yoghourt;

(5) flatly paving the yoghourt obtained in the step (4) in a sterile mould, and putting the yoghourt into a freezer at the temperature of-38 ℃ for freezing for 8 hours to obtain frozen yoghourt;

(6) completely freezing the frozen yogurt obtained in the step (5), and then putting the frozen yogurt into a freeze dryer with the vacuum degree of 3pa for drying for 30h to obtain frozen yogurt blocks;

(7) and (4) after the freeze-dried yogurt blocks obtained in the step (6) are freeze-dried, sealing the freeze-dried yogurt blocks in a sterile bag, and vacuumizing to obtain the viable bacteria type yogurt blocks.

Comparative example 2

A preparation method of a live bacteria type yogurt block comprises the following raw materials: 82.982% of raw milk, 7% of white granulated sugar, 0.8% of milk protein powder, 0.048% of carrageenan, 0.024% of carboxymethyl cellulose, 0.048% of pectin, 0.025% of solid malt extract, 0.025% of enzymolysis oat powder, 2.25% of blueberry fruit granules, 2.25% of grape fruit granules, 2.25% of grapefruit fruit granules, 2.25% of pineapple fruit granules, 0.04% of lactobacillus rhamnosus, 0.004% of bifidobacterium lactis and 0.004% of lactobacillus casei, wherein the percentages are mass percentages of the total mass of the raw materials; the preparation method comprises the following steps:

(1) preheating raw milk to 55 ℃, adding pectin, carrageenan, carboxymethyl cellulose, solid malt extract and enzymolysis oat flour while stirring the raw milk, and stirring for 20min to obtain emulsion;

(2) preheating the emulsion obtained in the step (1) to 63 ℃, homogenizing under the homogenizing pressure of 19Mpa (the first-stage homogenizing pressure is 16Mpa, and the second-stage homogenizing pressure is 3Mpa), sterilizing in a tubular manner, cooling to 40 ℃, and adding lactobacillus rhamnosus and bifidobacterium lactis: fermenting the lactobacillus casei in an addition amount of 10:1:1 to obtain a fermentation base solution; wherein the sterilization temperature is 93 ℃ and the sterilization time is 8 min;

(3) after the fermentation base liquid in the step (2) is fermented until the acidity is 74 DEG T, ending the fermentation, turning over the cylinder, and cooling to 20 ℃ to obtain the yoghourt base liquid;

(4) adding blueberry fruit particles, grape fruit particles, grapefruit fruit particles and pineapple fruit particles into the yoghourt base liquid obtained in the step (3), and uniformly stirring to obtain yoghourt;

(5) flatly paving the yoghourt obtained in the step (4) in a sterile mould, and putting the yoghourt into a freezer at the temperature of-38 ℃ for freezing for 8 hours to obtain frozen yoghourt;

(6) completely freezing the frozen yogurt obtained in the step (5), and then putting the frozen yogurt into a freeze dryer with the vacuum degree of 3pa for drying for 30h to obtain frozen yogurt blocks;

(7) and (4) after the freeze-dried yogurt blocks obtained in the step (6) are freeze-dried, sealing the freeze-dried yogurt blocks in a sterile bag, and vacuumizing to obtain the viable bacteria type yogurt blocks.

Comparative example 3

A preparation method of a live bacteria type yogurt block comprises the following raw materials: 83.032% of raw milk, 7% of white granulated sugar, 0.8% of milk protein powder, 0.048% of carrageenan, 0.024% of carboxymethyl cellulose, 0.048% of pectin, 2.25% of blueberry fruit granules, 2.25% of grape fruit granules, 2.25% of grapefruit fruit granules, 2.25% of pineapple fruit granules, 0.04% of lactobacillus rhamnosus, 0.004% of bifidobacterium lactis and 0.004% of lactobacillus casei, wherein the percentages are mass percentages of the total mass of the raw materials; the preparation method comprises the following steps:

(1) preheating raw milk to 55 deg.C, adding pectin, carrageenan and carboxymethyl cellulose while stirring raw milk, and stirring for 20min to obtain emulsion;

(2) preheating the emulsion obtained in the step (1) to 63 ℃, homogenizing under the homogenizing pressure of 19Mpa (the first-stage homogenizing pressure is 16Mpa, and the second-stage homogenizing pressure is 3Mpa), sterilizing in a tubular manner, cooling to 40 ℃, and adding lactobacillus rhamnosus and bifidobacterium lactis: fermenting the lactobacillus casei in an addition amount of 10:1:1 to obtain a fermentation base solution; wherein the sterilization temperature is 93 ℃ and the sterilization time is 8 min;

(3) after the fermentation base liquid in the step (2) is fermented until the acidity is 73 DEG T, ending the fermentation, turning over the cylinder, and cooling to 20 ℃ to obtain the yoghourt base liquid;

(4) adding blueberry fruit particles, grape fruit particles, grapefruit fruit particles and pineapple fruit particles into the yoghourt base liquid obtained in the step (3), and uniformly stirring to obtain yoghourt;

(5) flatly paving the yoghourt obtained in the step (4) in a sterile mould, and putting the yoghourt into a freezer at the temperature of-38 ℃ for freezing for 8 hours to obtain frozen yoghourt;

(6) completely freezing the frozen yogurt obtained in the step (5), and then putting the frozen yogurt into a freeze dryer with the vacuum degree of 3pa for drying for 30h to obtain frozen yogurt blocks;

(7) and (4) after the freeze-dried yogurt blocks obtained in the step (6) are freeze-dried, sealing the freeze-dried yogurt blocks in a sterile bag, and vacuumizing to obtain the viable bacteria type yogurt blocks.

Comparative example 4

A preparation method of a live bacteria type yogurt block comprises the following raw materials: 83.012% of raw milk, 7% of sucrose, 0.8% of milk protein powder, 0.05% of solid malt extract and enzymolysis oat powder (adding amount is 1:1), 0.09% of mannitol and ascorbic acid (adding amount is 1:1), 9% of blueberry fruit grains, grape fruit grains, grapefruit fruit grains and pineapple fruit grains (adding amount is 1:1:1), and 0.05% of lactobacillus rhamnosus, bifidobacterium lactis and lactobacillus casei (adding amount is 10:1:1), wherein the percentages are mass percentages of the total mass of the raw materials; the preparation method comprises the following steps:

(1) preheating raw milk to 55 ℃, adding solid malt extract and enzymolysis oat powder while stirring the raw milk, and stirring for 20min to obtain emulsion;

(2) preheating the emulsion obtained in the step (1) to 63 ℃, homogenizing under the homogenizing pressure of 19Mpa (the first-stage homogenizing pressure is 16Mpa, and the second-stage homogenizing pressure is 3Mpa), sterilizing in a tubular manner, cooling to 40 ℃, and adding lactobacillus rhamnosus and bifidobacterium lactis: fermenting the lactobacillus casei in an addition amount of 10:1:1 to obtain a fermentation base solution; wherein the sterilization temperature is 93 ℃ and the sterilization time is 8 min;

(3) after the fermentation base liquid in the step (2) is fermented until the acidity is 75 DEG T, ending the fermentation, turning over the cylinder, and cooling to 20 ℃ to obtain the yoghourt base liquid;

(4) adding blueberry fruit particles, grape fruit particles, grapefruit fruit particles, pineapple fruit particles, mannitol and ascorbic acid into the yoghourt base solution obtained in the step (3), and uniformly stirring to obtain yoghourt;

(5) flatly paving the yoghourt obtained in the step (4) in a sterile mould, and putting the yoghourt into a freezer at the temperature of-38 ℃ for freezing for 8 hours to obtain frozen yoghourt;

(6) completely freezing the frozen yogurt obtained in the step (5), and then putting the frozen yogurt into a freeze dryer with the vacuum degree of 3pa for drying for 30h to obtain frozen yogurt blocks;

(7) and (4) after the freeze-dried yogurt blocks obtained in the step (6) are freeze-dried, sealing the freeze-dried yogurt blocks in a sterile bag, and vacuumizing to obtain the viable bacteria type yogurt blocks.

Comparative example 5

A preparation method of a live bacteria type yogurt block comprises the following raw materials: 82.935% of raw milk, 7% of sucrose, 0.8% of milk protein powder, 0.12% of pectin, carrageenan and carboxymethyl cellulose (the addition amount is 2: 2:1), 0.05% of solid malt extract and enzymolysis oat powder (the addition amount is 1:1), 0.09% of mannitol and ascorbic acid (the addition amount is 1:1), 9% of blueberry fruit grains, grape fruit grains, grapefruit fruit grains and pineapple fruit grains (the addition amount is 1:1:1), 0.05% of lactobacillus bulgaricus and streptococcus thermophilus, wherein the percentages are mass percentages of the total mass of the raw materials; the preparation method comprises the following steps:

(1) preheating raw milk to 55 ℃, adding pectin, carrageenan, carboxymethyl cellulose, solid malt extract and enzymolysis oat flour while stirring the raw milk, and stirring for 20min to obtain emulsion;

(2) preheating the emulsion obtained in the step (1) to 63 ℃, homogenizing under the condition of a homogenizing pressure of 19Mpa (a first-stage homogenizing pressure of 16Mpa and a second-stage homogenizing pressure of 3Mpa), sterilizing in a tubular manner, cooling to 40 ℃, adding lactobacillus bulgaricus and streptococcus thermophilus, and fermenting to obtain a fermentation base solution; wherein the sterilization temperature is 93 ℃ and the sterilization time is 8 min;

(3) after the fermentation base liquid in the step (2) is fermented until the acidity is 75 DEG T, ending the fermentation, turning over the cylinder, and cooling to 20 ℃ to obtain the yoghourt base liquid;

(4) adding blueberry fruit particles, grape fruit particles, grapefruit fruit particles, pineapple fruit particles, mannitol and ascorbic acid into the yoghourt base solution obtained in the step (3), and uniformly stirring to obtain yoghourt;

(5) flatly paving the yoghourt obtained in the step (4) in a sterile mould, and putting the yoghourt into a freezer at the temperature of-38 ℃ for freezing for 8 hours to obtain frozen yoghourt;

(6) completely freezing the frozen yogurt obtained in the step (5), and then putting the frozen yogurt into a freeze dryer with the vacuum degree of 3pa for drying for 30h to obtain frozen yogurt blocks;

(7) and (4) after the freeze-dried yogurt blocks obtained in the step (6) are freeze-dried, sealing the freeze-dried yogurt blocks in a sterile bag, and vacuumizing to obtain the viable bacteria type yogurt blocks.

Aiming at the comparative examples 1 to 5 and the example 3, the indexes of the fermentation acidity, the fermentation time, the preference, the number of probiotics in the yogurt block, the preference and the like of the obtained viable bacteria type yogurt block are counted and measured, wherein the preference statistics is to test and grade the preference of 30 people by adopting a proper sensory evaluation method (0-9 points, 9 points are full points and represent the favorite)

The method for measuring the number of the probiotics in the yogurt block adopts a method for measuring the total number of the lactic acid bacteria in food microbiological inspection of national standard GB 4789.35-2016 (GB 4789.35-2016) for food safety; specific results are shown in table 1 below:

TABLE 1 comparison of the relevant indices for example 3 and comparative examples 1-5

From the results shown in the above table, it is found that the addition of the proliferation agent (solid malt extract, enzymatic oat flour) can shorten the fermentation time from 20 hours in comparative example 1 to 13 hours in example 3, and the fermentation time is shortened by 7 hours, and the number of probiotics is slightly increased. If the freeze-drying protective agent is added in the freeze-drying stage, the number of probiotics in the yogurt block is obviously higher than that of the yogurt block without the freeze-drying protective agent; compared with the fermentation time and the number of probiotics in the embodiment 3, the positive effects of the invention can be verified more easily because no proliferation agent and freeze-drying protective agent are added in the comparative example 3, namely, the proliferation of the probiotics in the milk can be accelerated by adding the solid malt extract and the enzymolysis oat flour, the fermentation speed is increased, and the fermentation time is shortened; the freeze-drying protective agent is added, so that the activity of probiotics in the yoghourt can be ensured to a certain extent, massive death of probiotics in the freeze-drying process is avoided, and the quantity of the probiotics in the obtained yoghourt block is ensured; comparative example 4 no stabilizer was added and the resulting yogurt block was hard, not crispy, had a large impact on mouthfeel and had low preference. And the common yoghurt starter culture is selected, so that the fermentation time can be greatly reduced, but the yoghurt block does not contain probiotics.

The above-described embodiments are merely illustrative of one or more embodiments of the present invention, which are described in more detail and detail, but are not to be construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention.