Fermented yoghurt and method for its preparation

Abstract

The application provides a fermented yoghourt and a preparation method thereof, wherein the raw materials of the fermented yoghourt comprise 70-80 wt.% of cow milk, 1-3 wt.% of protein, 5-8 wt.% of milk powder, 3-6 wt.% of allulose, 0.1-0.3 wt.% of potassium-containing compounds and 0.001-0.002 wt.% of leavening agent. The fermented yoghourt provided in the application has a delicate taste, a soft fermentation flavor, a rich caramel flavor, a uniform product color, no obvious precipitate and no whey separation, and can well meet the needs of consumers. Meanwhile, the fermented yoghourt provided in the application containing allulose has an improved post-acidification phenomenon compared with the fermented yoghourt containing glucose, and has a thicker texture.

Description

Technical Field

[0001] This invention relates to the field of fermented yogurt technology, specifically to a fermented yogurt and its preparation method. Background Technology

[0002] Yogurt, with its unique flavor and rich nutrition, is loved by consumers. Brown yogurt, in particular, is produced through the Maillard reaction between milk proteins and sugars, causing the milk to brown and creating a distinctive caramel flavor. This unique flavor enhances the drinking experience and increases appetite.

[0003] The market size of brown yogurt is gradually expanding, but most commercially available brown yogurts currently use the addition of glucose and lactase to introduce carbon sources for browning in milk, which is a single method; moreover, browned yogurt is more acidified after browning, and the texture of the product becomes looser and thinner than that of ordinary fermented yogurt. Summary of the Invention

[0004] In view of this, the present invention provides a fermented yogurt and a method for preparing the same. In the present invention, allulose is used to brown milk, and potassium ions are added to maintain the stability of the fermentation of the browned yogurt. The resulting fermented yogurt containing allulose has a rich flavor and a better taste, and the problem of post-acidification is improved.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0006] In a first aspect, the present invention provides a fermented yogurt, wherein the raw materials of the fermented yogurt include:

[0007] Milk 70-80 wt.%, protein 1-3 wt.%, milk powder 5-8 wt.%, allulose 3-6 wt.%, potassium compounds 0.1-0.3 wt.%, starter culture 0.001%-0.002 wt.%.

[0008] Furthermore, the raw materials in the fermented yogurt also include: compound gum powder, which includes at least one of sodium carboxymethyl cellulose, carrageenan, konjac gum, gellan gum, xanthan gum, modified starch, pectin, agar, locust bean gum, and guar gum.

[0009] Further, the emulsifier includes at least one of mono- and diglyceride fatty acid esters, diacetyl tartaric acid mono- and diglyceride esters, glyceryl monostearate, glyceryl monosuccinate, propylene glycol fatty acid esters, and propylene glycol alginate.

[0010] Furthermore, the protein is at least one of whey protein or casein.

[0011] Furthermore, the potassium-containing compound includes potassium chloride, and the potassium-containing compound includes at least one of potassium chloride, potassium lactate, potassium dihydrogen phosphate, potassium carbonate, and potassium citrate.

[0012] Furthermore, the starter culture includes at least one of Streptococcus thermophilus, Lactobacillus bulgaricus, Lactobacillus plantarum, and Pseudomonas parayogatus.

[0013] Furthermore, the ingredients in the fermented yogurt also include calcium chloride; and / or sweeteners.

[0014] Secondly, the present invention provides a method for preparing fermented yogurt as described above, the method comprising:

[0015] Add protein and milk powder to cow's milk, stir well, then add allulose and potassium-containing compounds, and brown at 95-98℃ for 20-35 minutes to obtain browned milk base;

[0016] A starter culture was added to the browned milk base for fermentation to obtain the fermented yogurt.

[0017] Furthermore, protein and milk powder are added to the milk to control the total protein content of the milk to 4-7 wt.% and the total solids content of the milk to 16-20 wt.%.

[0018] Furthermore, the preparation method further includes: shearing the fermented yogurt at a shearing rate of 1000-1800 rpm.

[0019] The beneficial effects of the above-described technical solution of the present invention are as follows:

[0020] This invention provides a fermented yogurt and its preparation method. The raw materials of the fermented yogurt include: 70-80 wt.% milk, 1-3 wt.% protein, 5-8 wt.% milk powder, 3-6 wt.% allulose, 0.1-0.3 wt.% potassium compounds, and 0.001%-0.002 wt.% starter culture. The fermented yogurt provided by this invention has a delicate texture, a mild fermented flavor, a rich caramel aroma, a uniform color, no obvious sediment, and no whey separation, thus well meeting consumer demand. Furthermore, the allulose-containing fermented yogurt provided by this invention exhibits improved acidification compared to fermented yogurt with added glucose, and has a thicker texture. Detailed Implementation

[0021] To further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, and not for limiting the present invention.

[0022] In a first aspect, the present invention provides a fermented yogurt, wherein the raw materials of the fermented yogurt include:

[0023] Milk 70-80 wt.%, protein 1-3 wt.%, milk powder 5-8 wt.%, allulose 3-6 wt.%, potassium compounds 0.1-0.3 wt.%, starter culture 0.001%-0.002 wt.%.

[0024] This invention provides a fermented yogurt, which utilizes allulose to induce a browning reaction with proteins in milk, resulting in a brown yogurt after fermentation. Specifically, this invention adjusts the total protein content to 4-7 wt.% by adding 1-3 wt.% protein to the milk, along with the proteins naturally present in the milk. Simultaneously, milk powder is added to adjust the total solids content to 16-20 wt.%. Within the aforementioned range of total protein and total solids content, the use of allulose for the browning reaction ensures a short browning time, a clear, uniform, and stable brown color. Furthermore, to further maintain the stability of the browned yogurt fermentation, the inventors discovered that adding potassium ions to the yogurt in this invention has a significant stabilizing effect. The fermented yogurt provided by this invention has a delicate texture, a mild fermented flavor, a rich caramel aroma, a uniform color, no obvious sediment, and no whey separation, thus well meeting consumer needs.

[0025] In some embodiments of the present invention, the milk may be fresh milk or a reconstituted product made from milk powder, condensed milk or whey protein, and the protein content of the milk is 3-4 wt.%.

[0026] In some embodiments of the present invention, the milk powder is preferably skimmed milk powder. If whole milk powder is used, the fermented yogurt may have the problem of fat floating on top.

[0027] In some embodiments of the present invention, the raw materials in the fermented yogurt further include: a composite gum powder, which includes at least one of sodium carboxymethyl cellulose, carrageenan, konjac gum, gellan gum, xanthan gum, modified starch, pectin, agar, locust bean gum, and guar gum.

[0028] In some embodiments of the present invention, the raw materials in the fermented yogurt further include: an emulsifier, wherein the emulsifier includes at least one of mono- and diglyceride fatty acid esters, diacetyl tartaric acid mono- and diglyceride esters, glyceryl monostearate, glyceryl monosuccinate, propylene glycol fatty acid esters, and propylene glycol alginate.

[0029] In some embodiments of the present invention, the protein is at least one of whey protein or casein. Whey protein or casein is preferred in the present invention to regulate the total protein content in milk, because both whey protein and casein are proteins derived from milk and can maintain consistency with the proteins in the milk base (i.e., milk), which has a beneficial effect on the stability of the prepared fermented yogurt.

[0030] In some embodiments of the present invention, the potassium-containing compound includes potassium chloride, and the potassium-containing compound includes at least one of potassium chloride, potassium lactate, potassium dihydrogen phosphate, potassium carbonate, and potassium citrate.

[0031] The inventors discovered that in the fermented yogurt system provided in this invention, the addition of potassium ions can synergistically enhance the browning reaction with allulose. Simultaneously, the amount of potassium ions added needs to be carefully controlled; an appropriate amount helps maintain the stability of the browned yogurt fermentation, resulting in a distinct, uniform, and colorless brown color. Potassium chloride is a common electrolyte supplement in the food industry; therefore, potassium chloride is the preferred potassium-containing compound, and the amount of potassium chloride added is 0.1–0.3 wt.%.

[0032] In some embodiments of the present invention, the starter culture includes at least one of Streptococcus thermophilus, Lactobacillus bulgaricus, Lactobacillus plantarum, and Pseudomonas parayogatus.

[0033] In some embodiments of the present invention, the raw materials in the fermented yogurt also include calcium chloride; and / or sweeteners.

[0034] In this invention, calcium chloride can be added to the fermented yogurt to increase its calcium content. Simultaneously, sweeteners can be added to mask some of the burnt and bitter taste caused by the browning reaction. Considering consumer demand for reduced sugar, low sugar, or sugar-free products, the sweeteners can preferably be some commonly available sugar substitutes.

[0035] Secondly, the present invention provides a method for preparing fermented yogurt as described above, the method comprising:

[0036] Protein and milk powder are added to cow's milk and stirred evenly. Allulose and potassium-containing compounds are then added to the mixture, and the mixture is browned at 95-98℃ for 20-35 minutes to obtain browned milk base. A starter culture is added to the browned milk base for fermentation to obtain the fermented yogurt.

[0037] In other embodiments of the present invention, protein and milk powder are added to cow's milk, and the total protein content in the cow's milk is controlled to be 4-7 wt.%; the total solids content in the cow's milk is controlled to be 16-20 wt.%.

[0038] In some other embodiments of the present invention, the preparation method further includes: shearing the fermented yogurt at a shearing rate of 1000-1800 rpm.

[0039] The present invention provides a method for preparing fermented yogurt as described above, the method comprising two processes: browning treatment using allulose and fermentation.

[0040] The browning treatment using allulose includes the following steps:

[0041] (1) Adjusting the protein and total solids content in milk: First, add 1-3 wt.% protein to milk in proportion, and then adjust the total solids content to 16-20 wt.% by adding milk powder. Stir evenly at 50-60℃.

[0042] (2) Control of browning conditions: Add 3-6 wt.% allulose and 0.1-0.3 wt.% potassium-containing compounds to the pretreated milk in step (1) and brown for 20-35 min at 95-98°C.

[0043] Fermentation includes the following steps:

[0044] (1) Add 0.001 to 0.002 wt.% of starter culture to the browned milk base and carry out fermentation;

[0045] (2) After the fermented yogurt is cooled to 4-6℃, it is demulsified and then passed through a high shear pump at a homogenization speed of 1000-1800rpm.

[0046] Furthermore, before fermentation, other substances can be added to the browned milk base, such as: 0.8-1.2 wt.% calcium chloride, 2-4 wt.% xylitol, 2-4 wt.% composite gum powder, and 0.8-1.2 wt.% emulsifier. Stir at 65°C for 20 minutes until homogeneous to obtain pre-fermented browned milk base; then add a starter culture to the pre-fermented browned milk base for fermentation.

[0047] The present invention will be further described below through some specific embodiments.

[0048] Example 1

[0049] In this embodiment, the raw materials for fermented yogurt include: fresh milk (protein content 3.2 wt.%), casein, skim milk powder, allulose, potassium chloride, calcium chloride, xylitol, compound gum powder (sodium carboxymethyl cellulose and carrageenan), emulsifier (mono- and diglyceride fatty acid esters) and starter culture (Lactobacillus bulgaricus and Lactobacillus plantarum).

[0050] This embodiment provides two processes: browning treatment of milk base using allulose and fermentation of milk base, specifically including the following steps:

[0051] 1. Browning treatment of milk base using allulose

[0052] (1) Adjusting the protein and total solids content in milk base: First, add 3wt.% casein to the milk according to the ratio, and then add skim milk powder to make the total solids content in the milk base reach 20wt.% and stir evenly at 55℃.

[0053] (2) Control of browning conditions: Add 6 wt.% allulose and 0.3 wt.% potassium chloride to the milk base pretreated in step (1) and brown at 98°C for 20 min.

[0054] 2. Fermentation of milk base

[0055] (1) Add 0.8 wt.% calcium chloride, 4 wt.% xylitol, 4 wt.% composite adhesive powder, and 1.2 wt.% emulsifier to the browned milk base and stir at 65°C for 20 min until uniform to obtain pre-fermented browned milk base;

[0056] (2) Add 0.002 wt.% of starter culture to the pre-fermented browned milk base in step (1) and carry out fermentation;

[0057] (3) Shearing refinement: After the fermented yogurt reaches the end point, it is cooled to 4-6℃ and demulsified, and then passed through a high shear pump at a homogenization speed of 1000rpm.

[0058] (4) Filling: Filling and sealing are carried out in a closed aseptic filling equipment. The filled yogurt is then refrigerated at 6°C for post-fermentation to obtain fermented yogurt containing allulose.

[0059] Example 2

[0060] The raw materials for the fermented yogurt in this embodiment are the same as those in Example 1.

[0061] This embodiment provides two processes: browning treatment of milk base using allulose and fermentation of milk base, specifically including the following steps:

[0062] 1. Browning treatment of milk base using allulose

[0063] (1) Adjusting the protein and total solids content in milk base: First, add 3wt.% casein to the milk according to the ratio, and then add skim milk powder to make the total solids content in the milk base reach 20wt.% and stir evenly at 55℃.

[0064] (2) Control of browning conditions: Add 3 wt.% allulose and 0.3 wt.% potassium chloride to the milk base pretreated in step (1) and brown at 98°C for 20 min.

[0065] 2. Fermentation of milk base: Same as in Example 1.

[0066] Example 3

[0067] The raw materials for the fermented yogurt in this embodiment are the same as those in Example 1.

[0068] This embodiment provides two processes: browning treatment of milk base using allulose and fermentation of milk base, specifically including the following steps:

[0069] 1. Browning treatment of milk base using allulose

[0070] (1) Adjusting the protein and total solids content in the milk base: First, add 1 wt.% casein to the milk according to the ratio, and then add skim milk powder to make the total solids content in the milk base reach 20 wt.%, and stir evenly at 55℃.

[0071] (2) Control of browning conditions: Add 3 wt.% allulose and 0.3 wt.% potassium chloride to the milk base pretreated in step (1) and brown at 98°C for 20 min.

[0072] 2. Fermentation of milk base: Same as in Example 1.

[0073] Example 4

[0074] The raw materials for the fermented yogurt in this embodiment include: the only difference from the raw materials in Example 1 is that casein is replaced with whey protein.

[0075] This embodiment provides two processes: browning treatment of milk base using allulose and fermentation of milk base, specifically including the following steps:

[0076] 1. Browning treatment of milk base using allulose

[0077] (1) Adjusting the protein and total solids content in milk base: First, add 3wt.% casein to the milk according to the ratio, and then add skim milk powder to make the total solids content in the milk base reach 20wt.% and stir evenly at 55℃.

[0078] (2) Control of browning conditions: Add 3 wt.% allulose and 0.3 wt.% potassium chloride to the milk base pretreated in step (1) and brown at 98°C for 20 min.

[0079] 2. Fermentation of milk base: Same as in Example 1.

[0080] Comparative Example 1

[0081] The ingredients for the fermented yogurt in this comparative example are the same as those in Example 1.

[0082] This comparative example provides two processes: browning treatment of milk base using allulose and fermentation of milk base, specifically including the following steps:

[0083] 1. Browning treatment of milk base using allulose

[0084] (1) Adjusting the protein and total solids content in the milk base: First, add 5 wt.% casein to the milk according to the ratio, and then add skim milk powder to make the total solids content in the milk base reach 20 wt.%, and stir evenly at 55℃.

[0085] (2) Control of browning conditions: Add 6 wt.% allulose and 0.3 wt.% potassium chloride to the milk base pretreated in step (1) and brown at 98°C for 20 min.

[0086] 2. Fermentation of milk base: Same as in Example 1.

[0087] Comparative Example 2

[0088] The ingredients for the fermented yogurt in this comparative example are: the only difference from the ingredients in Example 1 is that it does not contain casein.

[0089] This comparative example provides two processes: browning treatment of milk base using allulose and fermentation of milk base, specifically including the following steps:

[0090] 1. Browning treatment of milk base using allulose

[0091] (1) Controlling the protein and total solids content in the milk base: without adding casein, the total solids content in the milk base is made up to 20 wt. by adding skim milk powder to the cow's milk and stirring evenly at 55°C;

[0092] (2) Control of browning conditions: Add 6 wt.% allulose and 0.3 wt.% potassium chloride to the milk base pretreated in step (1) and brown at 98°C for 20 min.

[0093] 2. Fermentation of milk base: Same as in Example 1.

[0094] Comparative Example 3

[0095] The ingredients of the fermented yogurt in this comparative example include: the only difference from the ingredients in Example 1 is that it does not contain skim milk powder.

[0096] This comparative example provides two processes: browning treatment of milk base using allulose and fermentation of milk base, specifically including the following steps:

[0097] 1. Browning treatment of milk base using allulose

[0098] (1) Adjusting the protein and total solids content in milk base: First, add 3wt.% casein to the milk in proportion, without adding skim milk powder to increase the solids content, and stir evenly at 55℃.

[0099] (2) Control of browning conditions: Add 6 wt.% allulose and 0.3 wt.% potassium chloride to the milk base pretreated in step (1) and brown at 98°C for 20 min.

[0100] 2. Fermentation of milk base: Same as in Example 1.

[0101] Comparative Example 4

[0102] The ingredients for the fermented yogurt in this comparative example are: the only difference from the ingredients in Example 1 is that it does not contain potassium chloride.

[0103] This comparative example provides two processes: browning treatment of milk base using allulose and fermentation of milk base, specifically including the following steps:

[0104] 1. Browning treatment of milk base using allulose

[0105] (1) Adjusting the protein and total solids content in the milk base: First, add 3wt.% casein to the milk according to the ratio, and add skim milk powder to the milk to make the total solids content in the milk base reach 20wt.% and stir evenly at 55℃.

[0106] (2) Control of browning conditions: Add 6 wt.% allulose to the pretreated milk base in step (1) and brown at 98°C for 20 min;

[0107] 2. Fermentation of milk base: Same as in Example 1.

[0108] Comparative Example 5

[0109] The ingredients for the fermented yogurt in this comparative example are the same as those in Example 1.

[0110] This comparative example provides two processes: browning treatment of milk base using allulose and fermentation of milk base, specifically including the following steps:

[0111] 1. Browning treatment of milk base using allulose

[0112] (1) Adjusting the protein and total solids content in the milk base: First, add 3wt.% casein to the milk according to the ratio, and add skim milk powder to the milk to make the total solids content in the milk base reach 20wt.% and stir evenly at 55℃.

[0113] (2) Control of browning conditions: Add 6 wt.% allulose and 0.5 wt.% potassium chloride to the milk base pretreated in step (1) and brown at 98°C for 20 min.

[0114] 2. Fermentation of milk base: Same as in Example 1.

[0115] Comparative Example 6

[0116] The ingredients for the fermented yogurt in this comparative example are the same as those in Example 1.

[0117] This comparative example provides two processes: browning treatment of milk base using allulose and fermentation of milk base, specifically including the following steps:

[0118] 1. Browning treatment of milk base using allulose

[0119] (1) Adjusting the protein and total solids content in the milk base: First, add 3wt.% casein to the milk according to the ratio, and add skim milk powder to the milk to make the total solids content in the milk base reach 20wt.% and stir evenly at 55℃.

[0120] (2) Control of browning conditions: Add 2 wt.% allulose and 0.3 wt.% potassium chloride to the pretreated milk base in step (1) and brown at 98°C for 20 min.

[0121] 2. Fermentation of milk base: Same as in Example 1.

[0122] Comparative Example 7

[0123] The ingredients for the fermented yogurt in this comparative example are: the only difference from the ingredients in Example 1 is that allulose is replaced with glucose.

[0124] This comparative example provides two processes: browning treatment of milk base using glucose and fermentation of milk base, specifically including the following steps:

[0125] 1. Browning treatment of milk base using glucose

[0126] (1) Adjusting the protein and total solids content in the milk base: First, add 3wt.% casein to the milk according to the ratio, and add skim milk powder to the milk to make the total solids content in the milk base reach 20wt.% and stir evenly at 55℃.

[0127] (2) Control of browning conditions: Add 6 wt.% glucose and 0.3 wt.% potassium chloride to the pretreated milk base in step (1) and brown for 20 min at 98°C;

[0128] 2. Fermentation of milk base: Same as in Example 1.

[0129] Comparative Example 8

[0130] The ingredients for the fermented yogurt in this comparative example are: the only difference from the ingredients in Example 1 is that potassium chloride is replaced with sodium chloride.

[0131] This comparative example provides two processes: browning treatment of milk base using allulose and fermentation of milk base, specifically including the following steps:

[0132] 1. Browning treatment of milk base using allulose

[0133] (1) Adjusting the protein and total solids content in the milk base: First, add 3wt.% casein to the milk according to the ratio, and add skim milk powder to the milk to make the total solids content in the milk base reach 20wt.% and stir evenly at 55℃.

[0134] (2) Control of browning conditions: Add 6 wt.% allulose and 0.3 wt.% sodium chloride to the pretreated milk base in step (1) and brown at 98°C for 20 min.

[0135] 2. Fermentation of milk base: Same as in Example 1.

[0136] test:

[0137] 1. Sensory testing

[0138] Sensory evaluations of the taste and flavor were conducted on the fermented yogurts prepared in Examples 1-4 and Comparative Examples 1-8. The main evaluation items included: texture (presence or absence of sediment, whey separation, viscosity, smoothness, etc.), color (including color uniformity), flavor, and mouthfeel. A total of 30 participants conducted sensory evaluations of the products. The sensory scoring criteria are shown in Table 1, and the experimental results are summarized in Table 2.

[0139] Table 1

[0140]

[0141] Table 2

[0142]

[0143]

[0144] Continued from Table 2

[0145]

[0146] Continued from Table 2

[0147]

[0148]

[0149] As can be seen from the results in Table 2, the fermented milk prepared in Examples 1 to 4 has good texture, taste and flavor. The product has no whey separation, no sediment, rich caramel flavor, harmonious aroma, delicate taste, moderate sweet and sour taste and uniform flavor.

[0150] A comparison of Examples 1-4 and Comparative Examples 1-8 reveals that the following factors can affect the sensory evaluation of the product:

[0151] 1. Allulose addition amount: Through comparative analysis of Examples 1-2 and Comparative Example 6, it was found that the amount of allulose added is directly related to the browning color, and an appropriate amount of allulose added helps to form the browning color.

[0152] 2. Protein addition amount: Through comparative analysis of Examples 1, 3, and 4 and Comparative Examples 1 and 2, it was found that excessive protein content can lead to whey separation, which will affect the texture, color, and taste of fermented yogurt, but will not have a significant impact on the establishment of good flavor in the product.

[0153] 3. Amount of potassium chloride added: Through comparative analysis of Example 1 and Comparative Examples 4 and 5, the addition of potassium chloride has a promoting effect on the stability of the Maillard reaction. However, the amount of potassium chloride added needs to be within a suitable range. When the amount added is 0.1-0.3 wt.%, it can promote browning efficiency and improve the color and flavor of browned yogurt. When the amount added reaches 0.5 wt.%, it will have a negative impact on the quality of browned yogurt.

[0154] 4. Total solids content: Through comparative analysis of Example 1 and Comparative Example 3, it can be seen that the total solids content has the most significant impact on the texture and taste of brown yogurt. Sensory evaluation shows that when the total solids content is increased to 16-20 wt%, the brown yogurt exhibits a better texture and taste compared to other methods.

[0155] 5. Types of browning sugars: Through comparative analysis of Example 1 and Comparative Example 7, it can be seen that the browned yogurt prepared with allulose and glucose has little difference in overall sensory evaluation, indicating that the browned yogurt prepared by replacing glucose with allulose also has a good taste and flavor.

[0156] 6. Types of metal ions that promote browning: Through comparative analysis of Example 1 and Comparative Example 8, it can be seen that there is little difference in the overall sensory evaluation between browned yogurt with added potassium ions and those with added sodium ions. Potassium ions and sodium ions can be interchangeable in enhancing the sensory quality of browned yogurt.

[0157] 2. Acidity test

[0158] For the fermented yogurts prepared in Examples 1 and 2 and Comparative Examples 6 and 7, the acidity of the fermented products during their shelf life was determined at 25°C, in accordance with the national standard GB5009.239—2016 "National Food Safety Standard - Determination of Acidity in Food". Specific test results are shown in Table 3.

[0159] Table 3

[0160] Example 1 72.651°T 77.116°T 80.862°T 85.294°T 87.546°T Example 2 72.189°T 76.853°T 79.665°T 81.587°T 85.525°T Comparative Example 6 72.254°T 80.481°T 85.537°T 90.723°T 94.632°T Comparative Example 7 72.868°T 79.226°T 87.451°T 92.756°T 96.235°T

[0161] As can be seen from the results in Table 3, compared with Comparative Example 6, Examples 1 and 2 show that the acidification degree of fermented yogurt increases with the increase of allulose addition. However, when the addition amount is controlled within 6 wt.%, the acidity is still maintained below 90°T after 28 days. Compared with Comparative Example 7, Example 1 shows that allulose has a weaker acidification degree compared with glucose.

[0162] 3. Live bacteria count

[0163] The number of viable bacteria in the finished yogurt product during its shelf life was determined according to the method specified in the national standard GB4789.35-2016 "Lactic Acid Bacteria Count". Specific test results are shown in Table 4, unit: CFU / g.

[0164] Table 4

[0165] Example 1 <![CDATA[8×10 8 ]]> <![CDATA[4×10 8 ]]> <![CDATA[3×10 8 ]]> <![CDATA[1×10 7 ]]> <![CDATA[6×10 6 ]]> Example 2 <![CDATA[7×10 8 ]]> <![CDATA[4×10 8 ]]> <![CDATA[2×10 8 ]]> <![CDATA[2×10 7 ]]> <![CDATA[9×10 6 <!-- 10 -->]]> Comparative Example 6 <![CDATA[6×10 8 ]]> <![CDATA[3×10 8 ]]> <![CDATA[7×10 7 ]]> <![CDATA[4×10 7 ]]> <![CDATA[2×10 7 ]]> Comparative Example 7 <![CDATA[5×10 8 ]]> <![CDATA[3×10 8 ]]> <![CDATA[5×10 7 ]]> <![CDATA[7×10 6 ]]> <![CDATA[6×10 5 ]]>

[0166] As can be seen from Table 4, fermented yogurt made from allulose-browned milk has a higher number of live bacteria when stored at 25°C compared to glucose, but the number of live bacteria tends to decrease as the amount of allulose added increases.

[0167] 4. Adhesion and viscosity tests

[0168] Adhesion was tested for Examples 1, 3, and 4 and Comparative Examples 1, 2, and 3, and viscosity was tested for 120 seconds at a shear frequency of 50 1 / s. The specific test results are shown in Table 5.

[0169] The adhesiveness test method is as follows: the test is performed using a texture analyzer, and the conditions are set as follows: using a TA11 probe, contact load of 1g, test speed and retraction speed of 1mm / s.

[0170] The viscosity test method is as follows: using a rheometer, the viscosity is measured by scanning at a shear frequency of 50 l / s for 120 s.

[0171] Table 5

[0172] Example 1 16 121.21 Example 3 18 126.45 Comparative Example 1 15 113.66 Comparative Example 2 17 98.46 Comparative Example 3 14 94.16

[0173] As can be seen from Table 5, the total solids content and protein content have a significant impact on the adhesiveness and viscosity of fermented yogurt containing allulose, with the total solids content having a greater impact on the texture of the yogurt than the protein content.

[0174] 5. Color and 5-hydroxymethylfurfural test

[0175] For Example 1 and Comparative Examples 4 and 8, an SD-9011 colorimeter was used for measurement, and the CIELAB colorimetric system was selected for color representation. The B value was selected for data measurement. The larger the positive value, the more complete the browning reaction. In addition, the 5-hydroxymethylfurfural (5-HMF) content of the product was determined according to "NY / T 1332-2007 Determination of 5-hydroxymethylfurfural content in milk and dairy products by high performance liquid chromatography". The higher the 5-HMF index, the greater the food safety risk. The specific test results are shown in Table 6.

[0176] Table 6

[0177] Example 1 14 10.26 Comparative Example 4 9 11.54 Comparative Example 8 13 19.94

[0178] As can be seen from Table 6, by comparing the color of Example 1 and Comparative Example 4, the browned yogurt with added potassium ions is darker brown than the one without added potassium ions. By comparing Example 1 and Comparative Example 8, it was found that the browned yogurt with added potassium ions and the one with added sodium ions have similar browning colors. However, compared with Example 1 and Comparative Example 8, we can see that the browned yogurt with added sodium ions has a significantly higher 5-HMF content than the browned yogurt with added potassium ions. Compared with Example 1 and Comparative Example 4, the addition of potassium ions also has a slight inhibitory effect on 5-HMF in browned yogurt.

[0179] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship also changes accordingly.

[0180] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A fermented yogurt, characterized in that, The ingredients in the fermented yogurt include: Milk 70-80 wt.%, protein 1-3 wt.%, milk powder 5-8 wt.%, allulose 3-6 wt.%, potassium compounds 0.1-0.3 wt.%, starter culture 0.001%-0.002 wt.%; The method for preparing the fermented yogurt includes: Add protein and milk powder to cow's milk, stir well, then add allulose and potassium-containing compounds, and brown at 95-98℃ for 20-35 minutes to obtain browned milk base; A starter culture was added to the browned milk base for fermentation to obtain the fermented yogurt.

2. The fermented yogurt according to claim 1, characterized in that, The ingredients in the fermented yogurt also include: The composite adhesive powder includes at least one of sodium carboxymethyl cellulose, carrageenan, konjac gum, gellan gum, xanthan gum, modified starch, pectin, agar, locust bean gum, and guar gum.

3. The fermented yogurt according to claim 1, characterized in that, The ingredients in the fermented yogurt also include: Emulsifier, said emulsifier comprising at least one of mono- and diglycerides of fatty acids, diacetyl tartaric acid mono- and diglycerides, glyceryl monostearate, glyceryl monosuccinate, propylene glycol fatty acid ester, and propylene glycol alginate.

4. The fermented yogurt according to claim 1, characterized in that, The protein is at least one of whey protein or casein.

5. The fermented yogurt according to claim 1, characterized in that, The potassium-containing compound includes at least one of potassium chloride, potassium lactate, potassium dihydrogen phosphate, potassium carbonate, and potassium citrate.

6. The fermented yogurt according to claim 1, characterized in that, The fermenting agent includes at least one of Streptococcus thermophilus, Lactobacillus bulgaricus, and Lactobacillus plantarum.

7. The fermented yogurt according to claim 1, characterized in that, The ingredients in the fermented yogurt also include calcium chloride; and / or sweeteners.

8. The fermented yogurt according to claim 1, characterized in that, Add protein and milk powder to cow's milk, and control the total protein content in the cow's milk to 4-7 wt.%; control the total solids content in the cow's milk to 16-20 wt.%.

9. The fermented yogurt according to claim 1, characterized in that, The preparation method further includes: shearing the fermented yogurt at a shearing rate of 1000-1800 rpm.

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