Sucrose-free yoghourt and preparation method thereof

Abstract

The invention provides sucrose-free yoghurt and a preparation method thereof, and the preparation method comprises the following steps: 1) mixing raw milk with sugar substitutes to obtain a mixture; 2) adding a leavening agent and a first salt into the mixture, and performing fermentation treatment to obtain a fermentation product; and 3) performing demulsification treatment on the fermentation product, adding a second salt, and performing after-ripening treatment to obtain the sucrose-free yoghourt. The preparation method of the sucrose-free yoghurt provided by the invention has the characteristics of shortening the fermentation time of the yoghurt and improving the viscosity of the product.

Description

Technical Field

[0001] The invention relates to a sucrose-free yogurt, in particular to a sucrose-free yogurt and a preparation method thereof, and belongs to the field of fermented food. Background Art

[0002] With the vigorous promotion of the concept of sugar reduction / zero sugar, more and more products are beginning to develop zero sucrose series products. Among them, the yogurt field has gradually adopted sugar substitutes as sweeteners to balance the sweet and sour ratio of fermented products, making the finished yogurt sweet and sour.

[0003] At present, sugar alcohols and high-intensity sweeteners are often used in yogurt production to replace sucrose as yogurt sweeteners. However, the addition of sugar alcohols not only prolongs the fermentation time of yogurt, but also causes the viscosity of the finished yogurt to decrease, which in turn affects the texture and flavor of the finished yogurt.

[0004] Therefore, developing a method for preparing sucrose-free yogurt that can shorten the fermentation time and improve the viscosity of the product has become the current research direction. Summary of the invention

[0005] The invention provides a method for preparing sucrose-free yogurt, which has the characteristics of shortening fermentation time and improving product viscosity.

[0006] The invention also provides a sucrose-free yogurt, which has the characteristics of 0 sucrose and high viscosity.

[0007] The present invention provides a method for preparing sucrose-free yogurt, which comprises the following steps:

[0008] 1) mixing raw milk and sugar substitute to obtain a mixture;

[0009] 2) adding a fermentation agent and a first salt including a magnesium salt to the mixture to perform a fermentation treatment to obtain a fermentation product;

[0010] 3) The fermentation product is subjected to a demulsification treatment and then a post-ripening treatment to obtain a sucrose-free yogurt.

[0011] The preparation method as described above, wherein, further comprises adding a second salt containing magnesium salt to the system obtained after the demulsification treatment before the post-ripening treatment.

[0012] The preparation method as described above, wherein the mass ratio of the magnesium element in the first salt to the raw milk is 1:2500 to 1:13000, and / or the mass ratio of the magnesium element in the second salt to the raw milk is 1:7000 to 1:38000.

[0013] In the preparation method as described above, the first salt and the second salt each independently include at least one of a calcium salt and a zinc salt.

[0014] The preparation method as described above, wherein the mass ratio of calcium element in the first salt to raw milk is 1:3000 to 1:7000, and / or the mass ratio of zinc element in the second salt to raw milk is 1:5000 to 1:24000.

[0015] The preparation method as described above, wherein the temperature of the fermentation treatment is 42±1°C.

[0016] The preparation method as described above, wherein the pH value of the fermentation product is ≤4.6.

[0017] The preparation method as described above, wherein the temperature of the post-ripening treatment is 4-6°C, and / or the time of the post-ripening treatment is 10 hours.

[0018] The present invention also provides a sucrose-free yogurt, wherein the sucrose-free yogurt is prepared by using any of the methods described above, and the viscosity of the sucrose-free yogurt is ≥700 mPa.s.

[0019] The present invention provides a method for preparing sucrose-free yogurt, which accelerates the growth and metabolic rate of fermentation-related lactic acid bacteria by adding inorganic salts containing magnesium salts before fermentation and before post-ripening, so that the preparation method has the characteristics of shortening the fermentation time and improving the viscosity of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a flow chart of the method for preparing the sugar-free yogurt described in Example 1. DETAILED DESCRIPTION

[0021] In order to enable those skilled in the art to better understand the scheme of the present invention, the present invention is further described in detail below. The specific implementation methods listed below are only for describing the principles and features of the present invention. The examples are only used to explain the present invention and are not intended to limit the scope of the present invention. Based on the embodiments of the present invention, all other implementation methods obtained by ordinary technicians in the field without creative work are within the scope of protection of the present invention.

[0022] The first aspect of the present invention provides a method for preparing sucrose-free yogurt, comprising the following steps:

[0023] 1) mixing raw milk and sugar substitute to obtain a mixture;

[0024] 2) adding a fermentation agent and a first salt including a magnesium salt to the mixture for fermentation to obtain a fermentation product;

[0025] 3) The fermentation product is subjected to a demulsification treatment and then a post-ripening treatment to obtain a sucrose-free yogurt.

[0026] The present invention does not limit the selection of raw milk, and the raw milk can be selected from at least one of fresh cow's milk, fresh goat's milk, fresh deer's milk, fresh camel's milk, pasteurized cow's milk, pasteurized goat's milk, pasteurized deer's milk, pasteurized camel's milk, reconstituted cow's milk, reconstituted goat's milk, reconstituted deer's milk and reconstituted camel's milk.

[0027] The present invention also does not limit the selection of sugar substitutes, and the sugar substitute can be selected from at least one of xylitol, maltitol, and erythritol. In a specific embodiment, the sugar substitute is maltitol.

[0028] It is understood that in the preparation method provided by the present invention, the amount of sugar substitute added can be adjusted according to the desired sweetness-sourness ratio of the product. In one embodiment, the weight ratio of sugar substitute to raw milk is 1:24 to 1:49.

[0029] The present invention does not limit the temperature and time of the mixing operation, as long as the effect of dissolving the sugar substitute in the raw milk can be achieved. In one embodiment, the temperature of the mixing operation is 50 to 60 degrees Celsius, and the mixing operation time is 30 minutes.

[0030] In order to make the substances in the mixture evenly distributed, in one embodiment, before step 2), the mixture is further subjected to homogenization. The homogenization is carried out using a homogenizer, and the secondary pressure of the homogenization is 30-40 bar, and the primary pressure of the homogenization is 160-180 bar.

[0031] Furthermore, in order to kill all lactic acid bacteria in the mixture so that the lactic acid bacteria introduced by the fermentation agent in the subsequent fermentation process can occupy a dominant position, in one embodiment, before adding the fermentation agent and the first salt to the mixture, the mixture is sterilized. The sterilization process uses a tubular sterilization device, the sterilization process temperature is 90-95°C, and the time is controlled at 200-300s.

[0032] The present invention does not limit the components of the leavening agent, and a leavening agent commonly used in the technical field can be selected. For example, the leavening agent can include thermophilic streptococci and bulgaricus lactobacillus.

[0033] The first salt includes a magnesium salt. Specifically, the first salt may include at least one of magnesium chloride, magnesium sulfate, magnesium citrate, magnesium oxide, and magnesium glycinate.

[0034] It is easy to understand that the first salt may contain only magnesium salt or other substances in addition to magnesium salt. When the first salt contains other substances, the present invention does not limit the other components in the first mixed salt as long as they meet the requirement of not causing harm to human health.

[0035] The present invention does not limit the order of adding the leavening agent and the first salt, as long as both are added before the fermentation process. It is understood that the present invention also does not limit the form of adding the leavening agent and the first salt, and both raw materials can be added to the mixture in solid form, or at least one of the two raw materials can be dissolved in water first and then added to the mixture. In one implementation method, both raw materials are added to the mixture in solid form at the same time.

[0036] The present invention does not impose any limitation on the fermentation temperature, as long as the fermentation effect of the mixture of the first salt and the leavening agent can be achieved.

[0037] When the fermentation process is finished, since the lactic acid bacteria will continue to produce acid, the fermentation product needs to be demulsified to terminate the fermentation process and facilitate the post-ripening process. During the post-ripening process, the temperature needs to be controlled within 2 to 10 degrees Celsius, and the time is not limited, as long as the viscosity of the obtained sucrose-free yogurt product meets the requirements.

[0038] The inventors found that compared with the acid production time, fermentation time and product viscosity obtained when yogurt was prepared using sucrose as a sweetener, when sugar alcohol sweeteners were used instead of sucrose as sweeteners to prepare yogurt, the start of acid production and fermentation time during the fermentation process were significantly prolonged, and the viscosity of the finished yogurt was low. The inventors speculated that the reason for the above phenomenon is that when sugar alcohol sweeteners represented by maltitol, xylitol, and erythritol are present in the fermentation system, because the sugar alcohol sweetener molecules contain more hydroxyl groups, the hydroxyl groups are easily chelated with metal ions in the raw milk, making the above metal ions unable to be effectively used by lactic acid bacteria in the fermentation agent during the fermentation process. When there is a lack of available metal ions during the fermentation process, the growth and metabolism of lactic acid bacteria will be inhibited, which is manifested as a delay in the start of acid production and a prolonged fermentation time, and the viscosity of the yogurt product is low.

[0039] In response to the above phenomenon, the inventors found that when a first salt containing magnesium ions is additionally added to the mixture before fermentation, the starting acid production time and fermentation time of the fermentation system with added sugar alcohol sweeteners are significantly shortened, and the viscosity of the sweetened yogurt product is also significantly increased.

[0040] The inventors speculate that the above phenomenon occurs because magnesium ions are important activators of intracellular reactions and can be used by lactic acid bacteria in the fermentation agent. When the first salt is added before the fermentation process, the magnesium ions in the first salt can promote the growth and metabolism of lactic acid bacteria, accelerate the rate of lactic acid production, and help shorten the start of acid production and fermentation time in the fermentation process.

[0041] The method for preparing sucrose-free yogurt provided by the present invention improves the nutritional environment required by lactic acid bacteria in yogurt fermentation by adding salts containing magnesium ions before fermentation treatment, thereby making up for the defect that the growth and metabolism of lactic acid bacteria are inhibited when sugar alcohols are used as sweeteners, increasing the growth and metabolism rate of lactic acid bacteria, thereby increasing the fermentation rate and the viscosity of the finished yogurt, and making the finished yogurt have better texture and flavor. Specifically, the viscosity of the prepared sucrose-free yogurt is not less than 700 mPa.s.

[0042] Furthermore, the preparation method provided by the present invention further comprises adding a second salt containing magnesium salt to the system obtained after the demulsification treatment before the post-ripening treatment. Specifically, the second salt may contain at least one of magnesium chloride, magnesium sulfate, magnesium citrate, magnesium lactate, and magnesium glycinate. The second salt may contain only magnesium salt or may contain other substances in addition to magnesium salt. The present invention does not limit other components in the second salt, as long as it meets the requirement of not causing damage to human health.

[0043] The inventors found that when the second salt including magnesium salt is added before the post-ripening treatment, the obtained sucrose-free yogurt has a higher viscosity. In view of the above phenomenon, the inventors speculate that the reason may be that the magnesium ions contained in the second salt can further promote the lactic acid bacteria to produce viscous substances during the post-ripening treatment, which helps to further increase the viscosity of the yogurt product.

[0044] Furthermore, when the mass ratio of magnesium in the first salt to raw milk is 1:2500 to 1:13000, the fermentation time of the finished yogurt is shorter. The reason is that the appropriate magnesium ion concentration can better promote the growth and metabolism of lactic acid bacteria in the starter, which is beneficial for it to use lactose to produce lactic acid, making the fermentation time shorter; further, when the mass ratio of magnesium in the second salt to raw milk is 1:7000 to 1:38000, the viscosity of the finished yogurt is higher. The reason is that the appropriate magnesium ion concentration can better promote the growth and metabolism of lactic acid bacteria in the starter, produce sticky substances, and make the obtained sucrose-free yogurt product have a higher viscosity.

[0045] In one embodiment, the first salt and the second salt each independently include at least one of a calcium salt and a zinc salt.

[0046] The present invention does not limit the selection of calcium salt and zinc salt. In one embodiment, the calcium salt can be selected from at least one of calcium chloride, calcium carbonate, calcium citrate, calcium lactate, and milk calcium; the zinc salt can be selected from at least one of zinc oxide, zinc gluconate, zinc citrate, zinc lactate, and zinc sulfate.

[0047] Independent of each other means that although both the first salt and the second salt may include at least one of a calcium salt and a zinc salt, the types of calcium salt and zinc salt included in the first salt and the second salt may be different. For example, the first salt may include calcium chloride and zinc sulfate, while the second salt may include calcium sulfate and zinc chloride; for another example, the first salt may include calcium salt and zinc salt, while the second salt may include calcium salt but not zinc salt. By analogy, similar compound combinations are all within the scope of protection of the present invention.

[0048] When the first salt contains calcium salt and / or zinc salt in addition to magnesium salt, and further, the mass ratio of calcium element in the first salt to raw milk is 1:3000-1:7000, and / or the mass ratio of zinc element to raw milk is 1:2000-1:5000, the calcium ions and zinc ions contained in the calcium salt and zinc salt will make the magnesium ions more effective in accelerating the growth and metabolic rate of lactic acid bacteria, thereby shortening the time to start acid production, increasing the fermentation rate, and increasing the viscosity of the fermentation product.

[0049] When the second salt contains calcium salt and / or zinc salt in addition to magnesium salt, and further, the mass ratio of calcium element in the second salt to raw milk is 1:8000-1:27000, and / or the mass ratio of zinc element in the second salt to raw milk is 1:5000-1:24000, calcium ions and zinc ions will enhance the effect of magnesium ions in accelerating the growth and metabolic rate of lactic acid bacteria, so that the preparation method of sucrose-free yogurt of the present invention has the characteristic of higher product viscosity.

[0050] In one embodiment, when the temperature of the fermentation process is controlled at 42±1° C., the fermentation process is faster because the growth, metabolism and acid production rates of the lactic acid bacteria in the starter are faster at this temperature.

[0051] Furthermore, when the pH value of the fermentation product is ≤4.6 by controlling the fermentation temperature and fermentation time, the pH environment of the fermentation product is conducive to the production of viscous substances by thermophilic Streptococcus, thereby facilitating the improvement of the viscosity of the yogurt product.

[0052] When the temperature of the post-ripening treatment is 4-6°C, the thermophilic streptococcus produces viscous substances faster under this temperature environment. Therefore, when the above temperature is used for post-ripening treatment, the product obtained has a higher viscosity under the same treatment time. Furthermore, when the post-ripening treatment time is 10h, the viscosity of the obtained product can be further increased, so that the product yogurt has a good texture and taste.

[0053] The second aspect of the present invention protects a sucrose-free yogurt, which is obtained by using any of the above-mentioned preparation methods.

[0054] ≥700mPa.s, the sucrose-free yogurt has the characteristics of high viscosity while being sweet and sour, and has good texture and taste.

[0055] The preparation method of the sucrose-free yogurt provided by the present invention will be described in detail below with reference to specific embodiments.

[0056] Example 1

[0057] The present invention provides a method for preparing sucrose-free yogurt, specifically comprising: Figure 1 The process shown in the figure includes the following steps:

[0058] 1) 938.55 g of raw milk and 60 g of maltitol were mixed to obtain a mixture.

[0059] 2) After homogenizing and sterilizing the mixture, 0.05 g of a fermentation agent and 1.1 g of a first salt are added thereto, and the mixture is fermented at a temperature of 42±1° C. to obtain a fermentation product, wherein the pH of the fermentation product is ≤4.6.

[0060] The first salt comprises 0.6 g of zinc sulfate and 0.5 g of magnesium chloride.

[0061] 3) After the fermentation product is subjected to demulsification treatment, 0.3 g of the second salt is added and subjected to post-ripening treatment to obtain sucrose-free yogurt.

[0062] The second salt comprises 0.2 g of zinc sulfate and 0.1 g of magnesium chloride, the temperature of the post-ripening treatment is 4-6° C., and the time of the post-ripening treatment is 10 hours.

[0063] A yogurt sample A1 was prepared.

[0064] In this embodiment:

[0065] 1) The mass ratio of magnesium in the first salt to raw milk is 1:7419;

[0066] 2) The mass ratio of magnesium in the second salt to raw milk is 1:37097;

[0067] 3) The mass ratio of zinc element in the first salt to raw milk is 1:3872;

[0068] 4) The mass ratio of zinc element in the second salt to raw milk is 1:11616

[0069] Example 2

[0070] This embodiment is basically the same as Example 1, except that 60 g of maltitol in Example 1 is replaced by 50 g of erythritol, the mass of raw milk is 948.05 g, the composition of the first salt is 1.0 g of magnesium chloride and 0.4 g of calcium chloride, and the composition of the second salt is 0.2 g of magnesium chloride and 0.3 g of calcium chloride, and yogurt sample A2 is obtained.

[0071] In this embodiment:

[0072] 1) The mass ratio of magnesium in the first salt to raw milk is 1:3747;

[0073] 2) The mass ratio of magnesium in the second salt to raw milk is 1:18736;

[0074] 3) The mass ratio of calcium element in the first salt to raw milk is 1:6584;

[0075] 4) The mass ratio of calcium element in the second salt to raw milk is 1:8778.

[0076] Example 3

[0077] This embodiment is basically the same as Example 1, except that 60 g of maltitol in Example 1 is replaced by 40 g of xylitol, the mass of raw milk is 958.25 g, the composition of the first salt is 0.8 g of magnesium chloride and 0.6 g of zinc sulfate, and the composition of the second salt is 0.2 g of magnesium chloride and 0.1 g of zinc sulfate, and yogurt sample A3 is obtained.

[0078] In this embodiment:

[0079] 1) The mass ratio of magnesium in the first salt to raw milk is 1:4734;

[0080] 2) the mass ratio of magnesium in the second salt to raw milk is 1:18938;

[0081] 3) The mass ratio of zinc element in the first salt to raw milk is 1:3953;

[0082] 4) The mass ratio of zinc element in the second salt to raw milk is 1:23719.

[0083] Example 4

[0084] This embodiment is basically the same as Embodiment 1, except that 60 g of maltitol in Embodiment 1 is replaced by 20 g of xylitol, the mass of raw milk is 978.45 g, the composition of the first salt is 0.5 g of zinc sulfate and 0.5 g of magnesium chloride, and the composition of the second salt is 0.5 g of magnesium chloride, and yogurt sample A4 is obtained.

[0085] In this embodiment:

[0086] 1) The mass ratio of magnesium in the first salt to raw milk is 1:7735;

[0087] 2) The mass ratio of magnesium in the second salt to raw milk is 1:7735;

[0088] 3) The mass ratio of zinc element in the first salt to raw milk is 1:4844.

[0089] Example 5

[0090] This embodiment is basically the same as Embodiment 1, except that 60 g of maltitol in Embodiment 1 is replaced by 40 g of maltitol, the mass of raw milk is 958.35 g, the composition of the first salt is 1.4 g of magnesium chloride, and the composition of the second salt is 0.2 g of magnesium chloride, and yogurt sample A5 is obtained.

[0091] In this embodiment:

[0092] 1) The mass ratio of magnesium in the first salt to raw milk is 1:2706;

[0093] 2) The mass ratio of magnesium element in the second salt to raw milk is 1:18940.

[0094] Example 6

[0095] This embodiment is basically the same as Embodiment 1, except that the mass of raw milk is 936.85 g, the composition of the first salt is 0.5 g of magnesium chloride, 0.7 g of calcium chloride, and 1.0 g of zinc sulfate, and the composition of the second salt is 0.2 g of magnesium chloride, 0.3 g of calcium chloride, and 0.4 g of zinc sulfate, and yogurt sample A6 is obtained.

[0096] In this embodiment:

[0097] 1) The mass ratio of magnesium in the first salt to raw milk is 1:7406;

[0098] 2) The mass ratio of magnesium in the second salt to raw milk is 1:18515;

[0099] 3) The mass ratio of zinc element in the first salt to raw milk is 1:2319;

[0100] 4) The mass ratio of zinc element in the second salt to raw milk is 1:5797;

[0101] 5) The mass ratio of calcium element in the first salt to raw milk is 1:3718;

[0102] 6) The mass ratio of calcium element in the second salt to raw milk is 1:8675.

[0103] Example 7

[0104] This embodiment is basically the same as the embodiment 1, except that the mass of raw milk is 939.55 g, the composition of the first salt is 0.3 g of magnesium chloride, the composition of the second salt is 0.1 g of calcium chloride, and the yogurt sample A7 is obtained.

[0105] In this embodiment:

[0106] 1) The mass ratio of magnesium in the first salt to raw milk is 1:12379;

[0107] 2) The mass ratio of calcium element in the second salt to raw milk is 1:26099.

[0108] Example 8

[0109] This comparative example is basically the same as Example 1, except that the mass of raw milk is 938.35 g, the composition of the first salt is 1.0 g of magnesium chloride and 0.6 g of calcium chloride, and the second salt is not added, and yogurt sample A8 is obtained.

[0110] In this comparative example:

[0111] 1) The mass ratio of magnesium in the first salt to raw milk is 1:3709;

[0112] 2) The mass ratio of calcium element in the first salt to raw milk is 1:4344.

[0113] Comparative Example 1

[0114] This comparative example is basically the same as Example 1, except that the mass of raw milk is 938.05 g, the composition of the first salt is 1.4 g of zinc sulfate, and the composition of the second salt is 0.5 g of calcium chloride, and yogurt sample B1 is prepared.

[0115] In this comparative example:

[0116] 1) The mass ratio of zinc element in the first salt to raw milk is 1:1659;

[0117] 2) The mass ratio of calcium element in the second salt to raw milk is 1:5211.

[0118] Comparative Example 2

[0119] This comparative example is basically the same as Example 1, except that the mass of raw milk is 938.75 g, the first salt is not added, the composition of the second salt is 1.2 g of magnesium chloride, and yogurt sample B2 is prepared.

[0120] In this comparative example:

[0121] The mass ratio of magnesium element in the second salt to raw milk is 1:3092.

[0122] Comparative Example 3

[0123] This comparative example is basically the same as Example 1, except that neither the first salt nor the second salt is added, and a yogurt sample B3 is obtained.

[0124] Comparative Example 4

[0125] This comparative example is basically the same as Example 1, except that the mass of maltitol is 50 g, neither the first salt nor the second salt is added, the mass of raw milk is determined based on the total mass of raw milk, sugar substitute and starter being 1000 g, and yogurt sample B4 is prepared.

[0126] Comparative Example 5

[0127] This comparative example is basically the same as Example 1, except that the mass of maltitol is 40 g, neither the first salt nor the second salt is added, the mass of raw milk is determined based on the total mass of raw milk, sugar substitute and starter being 1000 g, and yogurt sample B5 is prepared.

[0128] Comparative Example 6

[0129] This comparative example is basically the same as Example 1, except that 60 g of erythritol is used instead of maltitol, neither the first salt nor the second salt is added, the mass of raw milk is determined based on the total mass of raw milk, sugar substitute, and starter being 1000 g, and yogurt sample B6 is prepared.

[0130] Comparative Example 7

[0131] This comparative example is basically the same as Example 1, except that 50 g of erythritol is used instead of maltitol, neither the first salt nor the second salt is added, the mass of raw milk is determined based on the total mass of raw milk, sugar substitute, and starter being 1000 g, and yogurt sample B7 is prepared.

[0132] Comparative Example 8

[0133] This comparative example is basically the same as Example 1, except that 40 g of erythritol is used instead of maltitol, neither the first salt nor the second salt is added, the mass of raw milk is determined based on the total mass of raw milk, sugar substitute, and starter being 1000 g, and yogurt sample B8 is prepared.

[0134] Comparative Example 9

[0135] This comparative example is basically the same as Example 1, except that 40 g of xylitol is used instead of maltitol, neither the first salt nor the second salt is added, the mass of raw milk is determined based on the total mass of raw milk, sugar substitute, and starter being 1000 g, and yogurt sample B9 is prepared.

[0136] Comparative Example 10

[0137] This comparative example is basically the same as Example 1, except that 30 g of xylitol is used instead of maltitol, neither the first salt nor the second salt is added, the mass of raw milk is determined based on the total mass of raw milk, sugar substitute, and starter being 1000 g, and yogurt sample B10 is prepared.

[0138] Comparative Example 11

[0139] This comparative example is basically the same as Example 1, except that 20 g of xylitol is used instead of maltitol, neither the first salt nor the second salt is added, the mass of raw milk is determined based on the total mass of raw milk, sugar substitute, and starter being 1000 g, and yogurt sample B11 is prepared.

[0140] Comparative Example 12

[0141] This comparative example is basically the same as Example 1, except that 60 g of sucrose is used instead of maltitol, neither the first salt nor the second salt is added, the mass of raw milk is determined based on the total mass of raw milk, sugar substitute, and starter being 1000 g, and yogurt sample B12 is prepared.

[0142] Test example

[0143] The acid production start time, fermentation time (i.e., the time from the start of fermentation to the pH value of the fermentation system dropping to 4.6), and viscosity of the yogurt samples were recorded during the production process of all the above yogurt samples. The viscosity of the yogurt samples was measured by using an Anton Paar MCR302 rheometer with a sample temperature of 20°C. After measuring 60 data, the average value was taken to calculate the viscosity of the yogurt samples.

[0144] The measured data are recorded in Table 1.

[0145] Table 1. Fermentation and product characteristics record

[0146]

[0147]

[0148] From the data in Table 1, we can see that:

[0149] 1) Compared with sample B3 prepared without adding the first salt or the second salt during the preparation process, samples A1-A8 prepared by adding at least the first salt during the preparation process had significantly shortened acid production start time and fermentation time, and significantly increased sample viscosity, which indicates that the first salt helps shorten the acid production start time and fermentation time and improve the viscosity of the product;

[0150] 2) Compared with sample A8 prepared by adding only the first salt, samples A4 and A5 prepared by adding the second salt containing only magnesium salt during the preparation process had shorter acid production start time and fermentation time and higher sample viscosity, which indicates that adding magnesium salt as the second salt helps to shorten the acid production start time and fermentation time and increase the viscosity of the product;

[0151] 3) When the first salt and the second salt are added at the same time, and the first or second salt contains at least one of a calcium salt and a zinc salt in addition to a magnesium salt, the acid production start time and the fermentation time of the prepared samples A1, A2, A3, A6, and A7 are further shortened, and the sample viscosity is further increased, which indicates that calcium salt and zinc salt are also helpful in shortening the acid production start time and the fermentation time and increasing the viscosity of the product;

[0152] 4) Since sample B2 only adds magnesium salt before the post-ripening treatment, the product has a longer acid production time and fermentation time, and the product viscosity is lower.

[0153] 5) It can be seen from samples B3-B11 that, without adding the first salt and the second salt, the higher the amount of sugar alcohol sweetener added, the longer the acid production time and fermentation time will be, and the lower the product viscosity will be.

[0154] 6) Compared with sample B12, sample A1 achieved the same acid production start time and fermentation time as sample B12 under the premise of using sugar substitute as sweetener, and the viscosity was higher than sample B12.

[0155] 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 sucrose-free yogurt, characterized in that: The following steps are involved: 1) mixing raw milk and sugar substitute to obtain a mixture; 2) adding a fermentation agent and a first salt including a magnesium salt to the mixture to perform a fermentation treatment to obtain a fermentation product; 3) The fermentation product is subjected to a demulsification treatment and then a post-ripening treatment to obtain a sucrose-free yogurt.

2. The preparation method according to claim 1, characterized in that: The method further comprises adding a second salt containing magnesium salt to the system obtained after the demulsification treatment before the post-ripening treatment.

3. The preparation method according to claim 2, characterized in that: The mass ratio of the magnesium element in the first salt to the raw milk is 1:2500 to 1:13000, and / or the mass ratio of the magnesium element in the second salt to the raw milk is 1:7000 to 1:38000.

4. The preparation method according to claim 2 or 3, characterized in that: The first salt and the second salt each independently include at least one of a calcium salt and a zinc salt.

5. The preparation method according to claim 4, characterized in that: The mass ratio of calcium element in the first salt to raw milk is 1:3000 to 1:7000, and / or the mass ratio of zinc element in the first salt to raw milk is 1:2000 to 1:5000.

6. The preparation method according to claim 4 or 5, characterized in that: The mass ratio of calcium element in the second salt to raw milk is 1:8000 to 1:27000, and / or the mass ratio of zinc element in the second salt to raw milk is 1:5000 to 1:24000.

7. The preparation method according to any one of claims 1 to 6, characterized in that: The temperature of the fermentation treatment is 42±1°C.

8. The preparation method according to any one of claims 1 to 7, characterized in that: The pH value of the fermentation product is ≤4.

6.

9. The preparation method according to any one of claims 1 to 8, characterized in that: The temperature of the post-ripening treatment is 4-6°C, and / or the time of the post-ripening treatment is 10 hours.

10. A sucrose-free yogurt, characterized in that: The sucrose-free yogurt is prepared by the preparation method according to any one of claims 1 to 9, and the viscosity of the sucrose-free yogurt is ≥ 700 mPa.s.

Images