Zero-fat low-sugar yoghourt and preparation method thereof

Abstract

The invention provides zero-fat low-sugar yoghourt and a preparation method thereof, the zero-fat low-sugar yoghourt comprises the following raw materials: skimmed milk, a fermentation inoculant, a sweetening agent and a protein product, the fat content of the skimmed milk is less than or equal to 0.3 g / 100mL, the protein content of the skimmed milk is greater than or equal to 6.0 g / 100mL, and the lactose content of the skimmed milk is less than or equal to 4.0 g / 100mL; the fermentation inoculant is composed of pichia kudriavzevii, lactobacillus helveticus and streptococcus thermophilus, and the ratio of the three strains is 2: 1: 5. According to the zero-fat low-sugar yoghourt disclosed by the invention, through selection of specific strains, good stability can be realized under the condition that a thickening agent and a stabilizing agent are not added, the product can be endowed with better oxidation resistance, human body metabolism improving efficacy and immunity regulating efficacy, and a green, clean and healthy yoghourt product is really obtained.

Description

Technical Field

[0001] The present invention relates to the field of dairy product processing, and particularly to a zero-fat and low-sugar yogurt and a preparation method thereof. Background Art

[0002] Yogurt is a traditional product with a long history. In recent years, consumers have continuously put forward new requirements for the taste, flavor and functionality of yogurt. The development of science and technology has greatly promoted the development of the functionality of traditional fermented yogurt and its products. Therefore, in a broad sense, it has the effects of improving defecation, enhancing immunity, regulating intestinal health, etc., and further develops in a healthier direction such as low-sugar, low-fat or even zero-fat.

[0003] At present, ambient-temperature yogurts of various flavors are increasingly popular among people. Ambient-temperature yogurt usually undergoes secondary pasteurization treatment to achieve a shelf life of 5-6 months. It is characterized by high viscosity and full taste, but it does not have the delicate and smooth feeling of low-temperature yogurt. The reason lies in that more food thickeners and stabilizers are added to the formula of ambient-temperature yogurt. At the same time, in production, the shear force generated during the transportation of yogurt and the pressure of about 1 atm in the equipment pipeline during the high-temperature sterilization process will cause certain damage to the structure of the yogurt. Summary of the Invention

[0004] Aiming at the deficiencies of the existing technology, the present invention provides a zero-fat and low-sugar yogurt and a preparation method thereof.

[0005] In the first aspect, the present invention provides a zero-fat and low-sugar yogurt, the raw materials of which include skim milk, fermentation starter, sweetener and protein products. The fat content of the skim milk is less than or equal to 0.3 g / 100 mL, the protein content is greater than or equal to 6.0 g / 100 mL, and the lactose content is less than or equal to 4.0 g / 100 mL. The fermentation starter is composed of Pichia kudriavzevii, Lactobacillus helveticus and Streptococcus thermophilus, and the ratio of the three strains is 2:1:5.

[0006] It should be noted that the zero-fat and low-sugar yogurt of the present invention does not contain thickeners and stabilizers. The present invention relies only on the exopolysaccharides produced by specific strains (Pichia kudriavzevii, Lactobacillus helveticus and Streptococcus thermophilus) themselves and the texture of the protein itself to achieve the stability of the yogurt system and avoid problems such as water separation and emulsion separation. Compared with the existing yogurt products added with thickeners and modified starches, it is more green, clean and healthy, and has a better taste.

[0007] Meanwhile, the specific strains selected in the present invention can also produce functional peptides during the fermentation process, endowing the product with better antioxidant capacity, improved human metabolism efficacy, and immune regulation efficacy. Specifically, Lactobacillus helveticus has a strong ability to hydrolyze proteins during the fermentation process. It first hydrolyzes proteins into oligopeptides with different molecular weights, and then Streptococcus thermophilus further decomposes the oligopeptides with larger molecular weights to produce oligopeptides with smaller molecular weights. The milk peptides composed of 2-6 amino acids produced by the two strains together have strong antioxidant activity and have a certain scavenging ability for DPPH free radicals, superoxide anion free radicals, and hydroxyl free radicals. In addition, the added Pichia kudriavzevii has a strong aroma-producing ability and is acid- and osmotic pressure-tolerant, and does not affect other flavor substances during the fermentation process. Under the condition of not adding essence, the yogurt obtained by the strain combination of the present invention has the best flavor. Both indicators are superior to the yogurt fermented by Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus.

[0008] In some embodiments of the present invention, the total addition amount of the fermentation starter is 80-200U / kg.

[0009] In some embodiments of the present invention, the skim milk is obtained by enzymatically hydrolyzing raw milk at 37°C in the presence of mesophilic lipase and then filtering through a microfiltration membrane.

[0010] The present invention abandons the traditional centrifugal defatting method. After enzymatic hydrolysis treatment with lipase, milk fat is separated by membrane filtration. This technology improves production continuity. After fat separation, the total fat content can be less than or equal to 0.3g / 100mL; at the same time, this technology retains the natural micellar structure of casein and reduces the water and lactose content in milk. The concentrated raw milk can achieve a protein content of greater than or equal to 6.0g / 100mL and a lactose content of less than or equal to 4.0g / 100mL.

[0011] In some embodiments of the present invention, the microfiltration membrane is selected as an MF microfiltration ceramic membrane.

[0012] Further, the dosage of the mesophilic lipase is 100-200U / g, the time of enzymatic hydrolysis is 1-2h, and the microfiltration membrane filtration is carried out at 8-12°C.

[0013] In some embodiments of the present invention, the raw material further includes an enzyme preparation, and the enzyme preparation is selected from one or more of laccase, neutral protease, and lactase.

[0014] Preferably, the enzyme preparation includes laccase and neutral protease.

[0015] More preferably, the enzyme preparation includes laccase, neutral protease, and lactase.

[0016] Neutral protease randomly cleaves the long protein chains to produce free branched-chain amino acids. Laccase can act on bovine serum albumin (BSA) in whey protein. Under their combined action and the extracellular polysaccharides produced by the strains, a finer cross-linked structure can be formed, further macroscopically locking the whey and moisture in the yogurt, forming a good texture and good viscosity, thus achieving a room-temperature yogurt without any thickeners or stabilizers, maintaining a good tissue state within a 6-month shelf life, and at the same time, under the condition of being kept at 37°C, there is no oxidation or non-enzymatic browning phenomenon.

[0017] The function of lactase is to hydrolyze lactose, accelerate the fermentation rate, and at the same time produce glucose to provide sweetness.

[0018] In some embodiments of the present invention, the addition amount of laccase is 40 U / kg, the addition amount of neutral protease is 50 U / kg, and the addition amount of lactase is 30 U / kg.

[0019] In some embodiments of the present invention, the protein product is membrane-filtered casein and / or concentrated milk protein, and the mass ratio of the protein product in the raw material is 3-6%.

[0020] Concentrated milk protein is a product with a high protein content, obtained by concentrating the protein components in milk. Casein is a phosphocalcium-binding protein, sensitive to acid, and will precipitate at a lower pH. Casein is the main protein in mammalian milk including cow, sheep, and human milk, also known as casein, caseinogen, and casein. Membrane-filtered casein refers to a high-purity casein product obtained by separating from milk through membrane filtration technology.

[0021] In some embodiments of the present invention, the raw material further includes inulin, and its mass ratio in the raw material is 2-4%.

[0022] Inulin is a reserve polysaccharide in plants, mainly derived from plants, and more than 36,000 species have been found, including 11 families such as Compositae, Campanulaceae, and Gentianaceae in dicotyledonous plants and Liliaceae and Gramineae in monocotyledonous plants. For example, inulin is rich in the tubers of Jerusalem artichoke and chicory, the roots of Dahlia pinnata, and the roots of thistles, and the inulin content in Jerusalem artichoke is the highest. In the present invention, inulin is added as dietary fiber, and after addition, it can improve the taste of yogurt.

[0023] In some embodiments of the present invention, the sweetener is D-allulose, and its mass ratio in the raw material is 0.01%.

[0024] The present invention can rely only on the sweetness produced by D-allulose and hydrolyzed lactose, without adding granulated sugar, which not only meets the sweetness requirement but also achieves low sugar.

[0025] The yogurt obtained by the present invention has a fat content of less than 0.5 g / 100 mL and a carbohydrate content of less than 5 g / 100 mL, meeting the claim requirements of GB 28050 for zero fat and low sugar.

[0026] In a second aspect, the present invention provides a method for preparing the above zero-fat and low-sugar yogurt.

[0027] The preparation method provided by the present invention includes: after material preparation, volume fixing, and sterilization, inoculating a fermentation starter into a skim milk base liquid for fermentation, and after fermentation, performing demulsification, cooling, and secondary pasteurization.

[0028] In the technical solution where the raw materials include an enzyme preparation, the enzyme preparation and the fermentation starter are co-inoculated into the skim milk base liquid for fermentation.

[0029] It can be understood that the material preparation step is to add raw material components other than the fermentation starter (if the formula contains an enzyme preparation, this also includes the enzyme preparation) to partially skimmed milk for dissolution and mixing. The volume fixing step is to fix the volume to a certain amount using skim milk. Generally, 1000 kg is used as the production volume fixing unit.

[0030] In some embodiments of the present invention, the sterilization is ultra-high temperature sterilization, sterilizing at a temperature of 105 - 115 °C for 10 - 40 s.

[0031] The advantage of ultra-high temperature sterilization is that it fully denatures the whey protein in the yogurt, making the casein in a naked state. On the one hand, it is easier to form the double-layer casein particle structure of the sour milk, and on the other hand, it makes the amino acid groups of the casein more likely to react under the catalysis of laccase.

[0032] In some embodiments of the present invention, the fermentation temperature is 37 ± 2 °C, the fermentation duration is ≥ 12 h, and the fermentation end point can be reduced to the range of pH 4.0 - 4.2.

[0033] In some embodiments of the present invention, after the cooling, before entering the secondary pasteurization, the yogurt is post-ripened for 1 - 3 h.

[0034] The proteolytic enzyme secreted by lactic acid bacteria during growth and metabolism hydrolyzes the milk protein to produce antioxidant active peptides. The number of lactic acid bacteria reaches the peak of the logarithmic phase during the post-ripening stage of the yogurt. Therefore, the post-ripening time is appropriately extended for the best antioxidant ability.

[0035] In a preferred embodiment of the present invention, the method for preparing the zero-fat and low-sugar yogurt includes the following steps:

[0036] (1) Preparation of skim milk: Raw milk is first passed through a sterilization separator to remove most of the microbial vegetative bodies and spores, 100 - 200 U / g of medium-temperature lipase is added, enzymatic hydrolysis is carried out at 37°C for 1 h, and then it is processed through an MF microfiltration ceramic membrane. The resulting skim milk has a total fat content of less than or equal to 0.3 g / 100 mL, a protein content of greater than or equal to 6.0 g / 100 mL, and a lactose content of less than or equal to 4.0 g / 100 mL.

[0037] (2) Ingredient preparation: The temperature of the milk is at 40 ± 5°C. First, membrane-filtered casein and / or concentrated milk protein are added, the stirring speed is kept constant at 1500 revolutions / min, and stirring is carried out for 5 - 10 min. Then other materials are slowly added. After the feeding is completed, shearing is maintained for 10 - 15 min.

[0038] (3) Volume adjustment: The liquid material is pumped into the semi-finished product tank using a pump, volume adjustment is carried out in the semi-finished product tank, and then it is left to hydrate for ≥ 30 min at a hydration temperature of 30 - 45°C.

[0039] (4) Sterilization: Ultra-high temperature sterilization conditions are 105 - 115°C, 10 - 40 s.

[0040] (5) Inoculation and fermentation: After sterilization, the liquid material is cooled to 15 - 42°C. The enzyme preparation and fermentation strains are added online into the liquid material together. After the liquid material is completely transported and all enters the fermentation tank, stirring is continued for 5 - 10 min to ensure that the enzyme preparation and fermentation strains are evenly mixed, then stirring is stopped, and within the range of 37 ± 2°C, fermentation is carried out for ≥ 12 h, and the fermentation end point is reduced to the pH range of 4.0 - 4.2.

[0041] (6) Demulsification and cooling: Demulsification and cooling to 4 - 10°C.

[0042] (7) After-ripening: The semi-finished yogurt product is left to stand in the tank for 1 - 3 h at 4 - 10°C.

[0043] (8) Secondary pasteurization: The sterilization temperature is 65 - 85°C, 4 - 30 s.

[0044] (9) Aseptic filling.

[0045] The present invention provides a zero-fat and low-sugar yogurt and its preparation method. Through the selection of specific strains, the zero-fat and low-sugar yogurt of the present invention can not only achieve good stability without adding thickeners and stabilizers, but also endow the product with better antioxidant capacity, improve the body's metabolic function and immune regulation function, and truly obtain a green, clean and healthy yogurt product. Detailed implementation mode

[0046] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions in the present invention will be clearly and completely described below. Apparently, the described embodiments are part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without any creative work belong to the scope of protection of the present invention.

[0047] For those not specifying specific techniques or conditions in the embodiments, follow the techniques or conditions described in the literature in the field or according to the product specifications. For reagents or instruments without indicating the manufacturer, they are all conventional products that can be obtained through regular channels.

[0048] Examples 1 - 5

[0049] Examples 1 - 5 respectively provide a zero - fat and low - sugar yogurt, and its raw material composition is shown in Table 1. The preparation method is as follows:

[0050] (1) Preparation of skim milk: Raw milk is first passed through a sterilization separator to remove most of the microbial vegetative bodies and spores, 100 - 200 U / g of mesophilic lipase is added, and enzymatic hydrolysis is carried out at 37 °C for 1 h. Then, it is treated with an MF microfiltration ceramic membrane at 8 - 12 °C (specifically, 12 °C in Example 1, 10 °C in Example 2, 8 °C in Example 3, 11 °C in Example 4, and 10.5 °C in Example 5). The total fat content of the obtained skim milk is less than or equal to 0.3 g / 100 mL, the protein content is greater than or equal to 6.0 g / 100 mL, and the lactose content is less than or equal to 4.0 g / 100 mL.

[0051] (2) Mixing of raw materials: The temperature of the skim milk is at 40 ± 5 °C. First, membrane - filtered casein and / or concentrated milk protein are added, the stirring speed is kept constant at 1500 revolutions per minute, and stirring is carried out for 5 - 10 min. Then, other materials are slowly added. After the feeding is completed, shearing is maintained for 10 - 15 min.

[0052] (3) Volume adjustment: The liquid material is pumped into the semi - finished product tank, volume adjustment is carried out in the semi - finished product tank, and then it is left to hydrate for ≥30 min at a hydration temperature of 30 - 45 °C.

[0053] (4) Sterilization: Ultra - high temperature sterilization conditions are 105 - 115 °C, 10 - 40 s.

[0054] (5) Inoculation and fermentation: After sterilization, the liquid material is cooled to 15 - 42 °C. The enzyme preparation and the fermentation strain are added online into the liquid material together. After the liquid material is completely transported and all enters the fermentation tank, stirring is continued for 5 - 10 min to ensure the uniform mixing of the enzyme preparation and the fermentation strain, then stirring is stopped, and fermentation is carried out at a temperature in the range of 37 ± 2 °C for ≥12 h until the fermentation end point is reduced to the pH range of 4.0 - 4.2.

[0055] (6) Demulsification and cooling: Demulsify and cool to 4 - 10 °C.

[0056] (7) After - ripening: Let the semi - finished yogurt stand in the tank for 1 - 3 h at 4 - 10 °C.

[0057] (8) Secondary pasteurization: The sterilization temperature is 65 - 85 °C for 4 - 30 s.

[0058] (9) Aseptic filling.

[0059] Table 1

[0060]

[0061]

[0062] Comparative Examples 1 - 6

[0063] Comparative Examples 1 - 6 each provide a kind of yogurt, and its raw material composition is shown in Table 2. Among them, the preparation methods of Comparative Examples 1 - 3 are the same as those of Example 2.

[0064] The difference between the preparation method of Comparative Example 4 and that of Example 5 lies in the preparation of skim milk in step (1). Specifically, raw milk is centrifuged to defat at 62 °C to obtain skim milk.

[0065] The difference between the preparation method of Comparative Example 5 and that of Example 5 lies in the preparation of skim milk in step (1). Specifically, without enzymatic hydrolysis, directly micro - filter using an MF micro - filtration ceramic membrane at 10 °C.

[0066] The difference between the preparation method of Comparative Example 6 and that of Example 5 lies in that the added strains are Lactobacillus bulgaricus and Streptococcus thermophilus.

[0067] Table 2

[0068]

[0069]

[0070] Carry out sensory evaluation and performance analysis on the yogurts obtained from each example and comparative example, as follows:

[0071] Experimental Example 1 Sensory evaluation

[0072] A total of 30 people participated in the sensory evaluation, with scores ranging from 1 - 10 points. Scores of 1 - 3 are poor, 4 - 5 are moderate, 6 - 7 are good, and 7 - 10 are the best. The results are shown in Table 3.

[0073] Table 3

[0074]

[0075]

[0076] Experimental Example 2 Texture Analysis

[0077] TA-XT plus physical property analyzer was used for texture detection. At 25°C, the yogurt was poured into a cylindrical sample cup with a diameter of 50 mm, and the sample addition amount each time was 105 g (about 3 / 4 of the sample cup). The probe was AB / E (a disc with a diameter of 35 mm), and the yogurt viscosity test module was used. The pre-test speed and the test speed were both 1.00 mm / sec, the return speed was 10 mm / sec, the test pressing distance was 30.00 mm, and the preset homogeneity threshold was 0.52 g, simulating the smaller threshold of the difference or discontinuity that can be perceived when the yogurt slides across the tongue and oral cavity. The results are shown in Table 4.

[0078] Table 4

[0079]

[0080] Note: Except for the homogeneity index, the larger the value of each index, the better the texture characteristics of the yogurt. The homogeneity index indicates that uneven fluid was encountered during the instrument detection process, which can be divided into two situations: it may be air bubbles in the yogurt, or material particles, or the yogurt breaks under the action of external force due to loose texture, and the feeling in the oral cavity is rough or uneven. Generally speaking, the lower the homogeneity index of the yogurt, the better the flow continuity, indicating that the yogurt is softer in the oral cavity.

[0081] Experimental Example 3 Rheological Properties and Stability Analysis

[0082] ① Rheological property detection: Anton Paar MCR302 rheometer, using a constant temperature speed-up and speed-down detection module, rotation speed 0 - 150 r / s, temperature 25°C, lasting for 6 min, reading the fitting calculation value corresponding to 75 seconds backward, which is the viscosity value, with the unit cp.

[0083] ② Stability analysis test: LUMiSizer stability analyzer, produced by ROM (Jiangsu) Instrument Co., Ltd. The detection conditions were that the sample was added to a 2 mL sample tube, at 25°C, rotation speed of 4000 revolutions per minute, scanned 10 times per minute, and read after 42 min.

[0084] The results are shown in Table 5.

[0085] Table 5

[0086]

[0087]

[0088] Experimental Example 4 Stability Test

[0089] After storing each group of samples under the condition of keeping warm at 42°C for 1 month, take them out and observe the appearance. The results are shown in Table 6.

[0090] Table 6

[0091] Sample group Stability condition Comparative example 1 Water separation, severe browning Comparative example 2 Water separation, slight browning Comparative example 3 Water separation, slight browning Comparative example 4 Water separation, slight browning Comparative example 5 Water separation, severe browning Comparative example 6 Water separation, severe browning Example 1 No water separation, no browning Example 2 No water separation, no browning Example 3 No water separation, no browning Example 4 No water separation, no browning Example 5 No water separation, no browning

[0092] Experimental Example 5 Free Radical Scavenging Test

[0093] The samples provided in the examples and comparative examples of the present invention were crushed and dissolved, and then the DPPH·, O2 - ·, ABTS + · free radical scavenging rates were detected. The specific test methods are as follows:

[0094] (1) Determination method of DPPH· scavenging rate: Weigh 2 g of the sample and add 18 g of deionized water. After shaking well, centrifuge at 4500 rpm for 10 minutes. Then pour the supernatant into a container, add deionized water (total mass 20 g) to the centrifuged precipitate and centrifuge again under the same conditions as above. Mix the supernatants of the two centrifugations, then perform ultrasonic extraction for 30 min, filter, evaporate the filtrate to dryness in a water bath at 65°C, dissolve it with an appropriate amount of 95% ethanol, and make up the volume to 25 mL in a volumetric flask. Centrifuge with a high-speed centrifuge (8000 rpm, centrifuge for 10 minutes), take the supernatant, and filter through a 0.45 μm microporous filter membrane to obtain the sample to be tested.

[0095] DPPH· is a stable free radical. Its ethanol solution is purple and has a strong absorption peak at 515 nm. Add the sample solution of 0.8 g / L to the reaction system of the same volume (5 mL of 95% ethanol 0.2 mmol / L DPPH·, pH = 8.2), and use pure water as the reference for zero adjustment in colorimetry. After reacting in a water bath at 25°C for 30 min, measure the absorbance at 515 nm. There are 3 parallel samples. After measurement, calculate the average value and calculate the free radical scavenging rate.

[0096] DPPH· free radical scavenging rate = [1 - A1 / A0] × 100%;

[0097] In the above formula, A0 is the absorbance of DPPH· without adding the sample at 515 nm, and A1 is the absorbance of the sample solution after reacting with DPPH· at 515 nm.

[0098] (2) Determination method of O2 - · free radical generation and scavenging rate: Pyrogallol can undergo autoxidation reaction under weak alkaline conditions to generate O2 - · free radicals. The O2 - · free radical scavenger can inhibit the absorption peak of the autoxidation product of pyrogallol at λ = 420 mm. Monitor with an ultraviolet-visible spectrophotometer, and the generation of O2 - · and the scavenging of O2- · Scavenging rate of free radicals. Take 4.5 mL of 50 mmol / L Tris-HCl buffer solution with pH = 8.2 and 4.2 mL of distilled water. After mixing, keep it in a water bath at 25 °C for 20 min. Immediately after taking it out, add 0.3 mL of 0.2 mmol / L pyrogallol preheated at 25 °C. The total volume is 9.0 mL. Measure the A420 value at the 10th s after the reaction starts (using Tris-HCl buffer solution with pH 8.2 as the reference) to obtain the light absorption value of the blank tube (i.e., A0). The reagents taken for measurement are the same as above, but before adding pyrogallol, add 2 mL respectively and reduce the corresponding volume of distilled water. Measure the A420 value at the 10th s after the reaction starts (using the sample solution with the same concentration but without adding pyrogallol as the reference), which is the light absorption value of the test tube to be measured (i.e., A1).

[0099] O2 - · Free radical scavenging rate S% = (A0 - A1) / A0 × 100%.

[0100] (3) ABTS + · Determination method of free radical scavenging rate: ABTS + · Weigh 2.0 mL of the solution, add a total of 10 μL of the sample solution obtained through pretreatment. Add absolute ethanol to the blank tube as the control group. In the control tube, ABTS + · Is replaced by the buffer solution. Place it for a total of 8 min at room temperature in a dark environment. Then measure the absorbance at a wavelength of 734 nm. Each sample is measured in parallel 3 times.

[0101] ABTS + · Free radical scavenging rate = 1 - (Ai - A0) / Aj × 100%;

[0102] Where Ai: The absorbance of the reaction of adding 2.0 mL of ABTS + · Solution with 10 μL of the sample solution;

[0103] Aj: The absorbance of the reaction of adding 2.0 mL of the buffer solution to 10 μL of the sample solution;

[0104] A0: The absorbance of the reaction of adding 2.0 mL of ABTS+· solution to 10 μL of absolute ethanol.

[0105] The test results are shown in Table 7.

[0106] Table 7

[0107] Sample group DPPH· scavenging rate O2-· scavenging rate ABTS+· radical scavenging rate Comparative example 1 15.2％ 11.0％ 3.3％ Comparative example 2 16.1％ 12.9％ 4.6％ Comparative example 3 17.4％ 14.1％ 5.1％ Comparative example 4 19.2％ 34.0％ 23.8％ Comparative example 5 9.1％ 19.8％ 6.4％ Comparative example 6 14.7％ 11.8％ 4.4％ Example 1 51.8％ 58.7％ 66.2％ Example 2 47.3％ 54.7％ 61.3％ Example 3 49.8％ 60.3％ 63.7％ Example 4 55.9％ 61.6％ 72.4％ Example 5 50.6％ 53.6％ 67.9％

[0108] 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 foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A zero-fat and low-sugar yogurt, characterized in that, Its raw materials include skim milk, fermentation starter, sweetener and protein products. The fat content of the skim milk is less than or equal to 0.3 g / 100 mL, the protein content is greater than or equal to 6.0 g / 100 mL, and the lactose content is less than or equal to 4.0 g / 100 mL. The fermentation starter consists of Pichia kudriavzevii, Lactobacillus helveticus and Streptococcus thermophilus, and the ratio of the three strains is 2:1:

5.

2. The zero-fat and low-sugar yogurt according to claim 1, wherein The skim milk is obtained by enzymatically hydrolyzing raw cow milk at 37 °C in the presence of mesophilic lipase and then filtering through a microfiltration membrane.

3. The zero-fat and low-sugar yogurt according to claim 2, characterized in that, The dosage of the mesophilic lipase is 100 - 200 U / g, the time of enzymatic hydrolysis is 1 - 2 h, and the microfiltration is carried out at 8 - 12 °C.

4. The zero-fat and low-sugar yogurt according to any one of claims 1 to 3, characterized in that, The raw materials further include an enzyme preparation, which is selected from one or more of laccase, neutral protease and lactase.

5. The zero-fat and low-sugar yogurt according to any one of claims 1 to 3, characterized in that, The protein product is membrane-filtered casein and / or concentrated milk protein, and the mass ratio of the protein product in the raw materials is 3 - 6%. The sweetener is D-allulose, and its mass ratio in the raw materials is 0.01%.

6. The zero-fat and low-sugar yogurt according to any one of claims 1 to 3, characterized in that, The raw materials further include inulin, and its mass ratio in the raw materials is 2 - 4%.

7. The preparation method of the zero-fat and low-sugar yogurt according to any one of claims 1-6, characterized in that, It includes: After batching, volume fixing and sterilization, inoculate the fermentation starter into the skim milk base liquid for fermentation. After fermentation, carry out demulsification, cooling and secondary pasteurization.

8. The preparation method of the zero-fat and low-sugar yogurt according to claim 7, characterized in that, Inoculate the enzyme preparation and the fermentation starter into the skim milk base liquid for fermentation together.

9. The preparation method of the zero-fat and low-sugar yogurt according to claim 7, characterized in that, After the cooling, before entering the secondary pasteurization, carry out after-ripening of the yogurt for 1 - 3 h.

10. The preparation method of the zero-fat and low-sugar yogurt according to claim 7, characterized in that, The sterilization is ultra-high temperature sterilization, sterilizing at 105 - 115 °C for 10 - 40 s.

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