Red taro yogurt and preparation method thereof

Abstract

The invention belongs to the technical field of yogurt product processing, and specifically relates to a red taro yogurt and a preparation method thereof. The yogurt comprises the following raw material components based on 1000 parts by weight: 300-400 parts of red taro strips, 50-100 parts of millet, 20-50 parts of pumpkin seed powder, 400-500 parts of pure water, 50-80 parts of food additives, and 4-6 parts of composite bacteria; in the yogurt, EAA / TAA is between 39-42%, and EAA / NEAA>65%. The present invention uses red taro with high nutritional value as the main raw material, and the red taro yogurt prepared by combining millet and pumpkin seed powder has high protein content, is rich in essential amino acids for the human body, and has EAA / TAA of about 40%, and EAA / NEAA of more than 68%, which can meet the requirements of the ideal protein model recommended by FAO / WHO, has a delicate and smooth taste, unique flavor, high nutritional value, and can effectively regulate the balance of human intestinal flora.

Description

Technical Field

[0001] The invention belongs to the technical field of yogurt product processing, and particularly relates to red taro yogurt and a preparation method thereof. Background Art

[0002] Yogurt is a sweet and sour milk drink. It is made from milk, pasteurized, and then beneficial bacteria are added to the milk. After fermentation, it is bottled. It is rich in protein, calcium and vitamins. Yogurt products on the market are mostly coagulated, stirred, and fruit-flavored with various juices, jams and other auxiliary ingredients. However, this type of yogurt either has only fruit flavor without pulp, or the pulp sinks and has poor stability, which directly affects the taste and has low nutritional value.

[0003] Red bud taro is one of the taro varieties and a famous local specialty of Shangrao, Jiangxi. Its skin is yellow-brown and the buds are pink. Red bud taro is easy to cook, and after cooking, the meat is delicate and smooth, sweet and delicious, and the starch granules are small and easy to digest. The quality and flavor are the best among taro. Red bud taro is rich in crude protein, starch and crude fiber, and the crude fat content is relatively low. It is a low-calorie food. Studies have shown that red bud taro can obtain 16 kinds of amino acids after acid hydrolysis (tryptophan is destroyed during the hydrolysis process), including 7 essential amino acids for the human body and 2 semi-essential amino acids, accounting for 39.87% of the total protein, with high nutritional value. In addition, in addition to the low content of VC in red bud taro, the content of VB1, VB2 and carotene is relatively high, especially carotene, which not only has the function of delaying aging, preventing cancer and cardiovascular diseases, but also can be converted into VA to promote normal growth and development of the human body. Red bud taro also contains mineral elements similar to those required by the human body, among which potassium content is the highest. It also contains a certain amount of fluorine, which has the effect of protecting teeth. Red taro is rich in nutritional value and meets the physiological needs of the human body. Currently, it is mainly made into foods such as red taro powder, red taro rice noodles, and red taro crisps, which have relatively narrow applicability. If red taro is made into yogurt, its applicability will be improved to a certain extent. Summary of the invention

[0004] The invention aims to provide a red taro yogurt and a preparation method thereof. The red taro yogurt uses red taro with high nutritional value as a main raw material and is prepared by adding millet and pumpkin seed powder. The prepared red taro yogurt has high protein content and is rich in essential amino acids for the human body. The EAA / TAA ratio is about 40%, and the EAA / NEAA ratio is greater than 65%. The ideal protein model requirements recommended by FAO / WHO can be met, and the nutritional value is high.

[0005] To achieve the above purpose, the present invention provides a red taro yogurt, which comprises the following raw material components based on 1000 parts by weight of the yogurt: 300-400 parts of red taro strips, 50-100 parts of millet, 20-50 parts of pumpkin seed powder, 400-500 parts of pure water, 50-80 parts of food additives and 4-6 parts of composite bacteria; in the yogurt, EAA / TAA is between 39-42%, and EAA / NEAA>65%.

[0006] Red bud taro is rich in various mineral elements that are beneficial to the human body. It has the characteristics of high fiber, high protein, low fat, low calories, etc. It has nutritional and health value, especially its complete amino acid variety and high content of essential amino acids for the human body. It is an excellent protein source. Relevant studies have shown that its essential amino acids / total amino acids (EAA / TAA) is 41.43%, and its essential amino acids / 10 non-essential amino acids (EAA / NEAA) is 70.73%, but its tryptophan and methionine content is relatively low. According to the ideal protein model recommended by the Food and Agriculture Organization of the United Nations / World Health Organization (FAO / WHO), the amino acid composition of good quality protein is about 40% EAA / TAA, and EAA / NEAA is more than 60%. At the same time, the recommended values ​​of 8 essential amino acids are given. Millet has high nutritional value, containing 9.2-14.7% protein, as well as unsaturated fatty acids, vitamins, potassium and iron, etc. It has the effect of preventing and treating indigestion. Its tryptophan content is the highest among cereals, which has the function of regulating sleep and is also rich in methionine. Pumpkin seeds are seeds of pumpkin, rich in unsaturated fatty acids, protein, microorganism B1, vitamin C, etc., and have a relatively high tryptophan content. They also contain rich pantothenic acid, which can relieve static angina pectoris and lower blood pressure, and also have the effect of killing human parasites. Therefore, the present invention uses red bud taro as the main raw material, and adds millet and pumpkin seed powder with relatively high tryptophan and methionine content to ferment together, further adjusts the amino acid pattern, and provides a red bud taro yogurt containing a high-quality amino acid pattern and rich in nutrients, which meets the amino acid needs of the human body and provides rich nutrition.

[0007] Preferably, in the above technical solution, the composite bacteria is a mixed bacteria of at least 5 kinds of bacteria in any proportion including Lactobacillus bulgaricus, Streptococcus thermophilus, Lactobacillus acidophilus, Lactobacillus plantarum, Lactococcus lactis, Lactobacillus casei, Bifidobacterium lactis, Bifidobacterium longum and Lactobacillus rhamnosus, among which Streptococcus thermophilus, Lactobacillus plantarum and Lactococcus lactis must be contained.

[0008] Lactobacillus bulgaricus is a lactic acid bacillus that can ferment sugar to obtain energy and produce a large amount of lactic acid; Streptococcus thermophilus is a facultative anaerobic or microaerobic Gram-positive bacterium, a live yogurt bacterium that can produce lactase, which can help lactose intolerance digest lactose, and at the same time can produce extracellular polysaccharides, bacteriocins and vitamins, with high safety; Lactobacillus acidophilus belongs to the genus Lactobacillus, a Gram-positive bacillus, which can adjust the balance of intestinal flora and inhibit the proliferation of harmful intestinal microorganisms. It can be used in combination with Lactobacillus bifidum to produce lactic acid and acetic acid, which can improve the utilization rate of calcium, phosphorus and iron, promote the absorption of iron and vitamin D, produce vitamin K and vitamin B, and can also reduce the absorption of cholesterol and reduce the damage of radiation to the human body; Lactobacillus plantarum is also a kind of lactic acid bacteria, which is a homofermentative lactic acid bacterium with health functions such as immune regulation, inhibition of pathogenic bacteria, maintenance of intestinal flora balance, and promotion of nutrient absorption Use; Lactococcus lactis is an important model bacteria in the genus Lactobacillus. It grows fast and has a relatively simple metabolism. It is widely used in dairy products such as yogurt; Lactobacillus casei is a Gram-positive bacteria of the genus Lactobacillus. It is a probiotic that can tolerate the defense mechanism of the organism and survive in large numbers in the intestine, playing a role in regulating the balance of intestinal flora and promoting human digestion and absorption; Bifidobacterium lactis and Bifidobacterium longum are both bifidobacteria, which are physiologically beneficial bacteria and have many important physiological functions for human health, such as biological barrier, nutritional effect, anti-tumor effect, immune enhancement effect, improvement of gastrointestinal function, and anti-aging; Lactobacillus rhamnosus belongs to the genus Lactobacillus, has a high intestinal adhesion rate, strong colonization ability, and has the functions of effectively lowering cholesterol and promoting cell division. It can play an important physiological health care function such as regulating intestinal flora, preventing and treating diarrhea, eliminating toxins, preventing tooth decay, improving the body's immunity and anti-cancer. The present technical solution uses composite bacteria, which not only have the fermentation function to decompose macromolecules into small molecules, but also act as functional bacteria after consumption to regulate the balance of intestinal flora, improve the absorption rate of nutrients, and inhibit pathogenic bacteria.

[0009] Preferably, in the above technical solution, the total number of viable bacteria of the composite bacteria is greater than 1×10 8 cfu / g.

[0010] Preferably, in the above technical solution, the food additive is maltitol. Maltitol is a new type of functional sweetener. Due to its low calorie, non-caries, and calcium absorption promoting physiological properties, it is added to yogurt to increase sweetness without being quickly decomposed and can also promote calcium absorption.

[0011] The present invention also provides a method for preparing red taro yogurt, the preparation method comprising the following steps:

[0012] S1. Raw material pretreatment: Select freshly picked red taro, wash the mud and sand, peel it, cut it into strips for later use; shell the pumpkin seeds, fry them, and crush them for later use;

[0013] S2. Cooking; the strips of red taro and millet were placed in a steamer and steamed for 20-40min, cooled and set aside; this step uses steaming to effectively prevent the loss of nutrients in red taro and millet, retaining the natural flavor;

[0014] S3. Preparation: According to the formula, the cooked red taro strips, millet, and 2 / 3 of pure water are put into a beater and crushed for 15-20 minutes to obtain a slurry; the pumpkin seed powder is added to a homogenizer, and an appropriate amount of pure water is added, and homogenized for 1-2 hours to obtain a homogenized material; the slurry and the homogenized material are mixed, and the mixture is put into the homogenizer again, and uniformly mixed for 0.5-1 hours to obtain a mixed solution for standby use; the composite bacteria, the remaining pure water, and the food additives are mixed evenly, and placed at a temperature of 37-42°C for acclimation to obtain an acclimated bacterial solution;

[0015] S4. Inoculation: Inoculate the acclimated bacterial solution into the mixture at room temperature and stir evenly to obtain an inoculum;

[0016] S5. Packaging: Fill the inoculum into bottled containers and seal them separately;

[0017] S6. Fermentation: Place the packaged bottled container in a constant temperature incubator at 42±2°C for 4-8 hours to obtain fermented yogurt;

[0018] S7. Post-ripening: transfer the fermented yogurt to 4-6°C for post-ripening for 10-15h to obtain the finished product of red taro yogurt.

[0019] Preferably, in the above technical solution S1, after the pumpkin seeds are crushed, 0.5-1 times the volume of pure water is added and mixed, neutral lipase is added under stirring at 50-55°C, treated for 0.5-1h, vacuum filtered, the filter residue is collected, and dried at 70-80°C to obtain defatted pumpkin seed powder. In this technical solution, by pretreating the pumpkin seed powder with neutral lipase, the fat in the pumpkin seeds can be decomposed into fatty acids, the fat content in yogurt can be reduced, the consumption is healthier, and the dispersion performance and stability can be improved.

[0020] Preferably, in the above technical solution, the mass ratio of the added amount of the neutral lipase to the pumpkin seed powder is 0.002-0.01:1.

[0021] Preferably, in the above technical solution, in S3, the slurry is further crushed in an ultrasonic crusher with an ultrasonic frequency of 40-50 Hz for 20-30 minutes. In this technical solution, the micro-tissues of red taro and millet can be effectively crushed by using ultrasound to further release the nutrients.

[0022] Preferably, in the above technical solution, in S3, the homogenizers are all aseptically treated, and the homogenization conditions are: pressure of 10-40MP a, temperature of 50-60°C, wherein the pressure is increased from 10MP a to 40MP a at intervals of 10MP a for the first homogenization; and the pressure is reduced from 40MP a to 10MP a at intervals of 10MP a for the second homogenization. In this technical solution, a homogenization pressure from low pressure to high pressure is first used, and the pumpkin seed powder can be evenly dispersed in water. As the pressure increases, the fat particles that have not been removed from the pumpkin seed powder are ultra-finely refined; then, homogenization from high pressure to low pressure is used to further ultra-fine the insoluble fibers in the mixed solution. As the pressure decreases, the components are evenly dispersed, which can further improve the stability of the mixed solution and increase the smoothness.

[0023] Preferably, in the above technical solution S3, the acclimation time is 6-8 hours. In this technical solution, by pre-mixing the composite bacteria with food additives, acclimating and activating the bacterial flora, the subsequent fermentation time can be shortened.

[0024] Preferably, in the above technical solution S5, the bottled container is pre-filled with sterile nitrogen.

[0025] Advantages compared to the prior art:

[0026] 1. The present invention uses red taro with high nutritional value as the main raw material, and prepares the red taro yogurt by mixing millet and pumpkin seed powder. The red taro yogurt has high protein content and is rich in 8 essential amino acids for the human body. The EAA / TAA ratio is between 39-42%, and the EAA / NEAA ratio is greater than 65%. The ideal protein pattern (amino acid pattern) recommended by FAO / WHO can be met, and the nutritional value is high.

[0027] 2. The present invention increases sweetness without increasing calories by adding safe food additives, and can also promote calcium absorption; by using composite bacteria, not only the fermentation effect is good, but also it is beneficial to regulate the balance of human intestinal flora and has the function of improving the absorption rate of nutrients.

[0028] 3. The preparation method of the present invention can effectively prevent the loss of nutrients by treating the raw materials separately; a crushing method combining beating and ultrasound is adopted to release the nutrients; a homogenization method from low pressure to high pressure and then from high pressure to low pressure is adopted to further ultra-fine the large particles, evenly disperse them, and improve the stability; after adding the domesticated composite bacteria, the yogurt ferments quickly and has a good effect. The final red taro yogurt has a delicate and smooth taste, a unique flavor, rich nutrition, and can effectively regulate the balance of human intestinal flora. DETAILED DESCRIPTION

[0029] The above-mentioned technical features of the present invention and the technical features specifically described below (such as implementation cases) can be combined with each other to form new or preferred technical solutions, but the present invention is not limited to these embodiments, and these embodiments do not limit the present invention in any way.

[0030] The experimental methods in the following examples are conventional methods unless otherwise specified. The preparations involved in the following examples are common commercial products unless otherwise specified and can be purchased from the market.

[0031] The present invention is described in further detail below in conjunction with embodiments:

[0032] Example 1

[0033] A red taro yogurt comprises the following raw material components based on 1000 parts by weight of the yogurt: 300 parts of red taro strips, 100 parts of millet, 50 parts of pumpkin seed powder, 466 parts of purified water, 80 parts of maltitol and 4 parts of composite bacteria.

[0034] The composite bacteria is a mixed bacteria of Lactobacillus bulgaricus, Streptococcus thermophilus, Lactobacillus plantarum, Lactococcus lactis, Lactobacillus casei, Bifidobacterium lactis, and Lactobacillus rhamnosus in a mass ratio of 1:1:1:1:1:1:1, and the total number of viable bacteria is greater than 1×10 8 cfu / g;

[0035] The preparation method comprises the following steps:

[0036] S1. Raw material pretreatment: freshly picked red taro is washed, peeled, and cut into strips for later use; pumpkin seeds are shelled, fried, and crushed for later use; after the pumpkin seeds are crushed, 1 volume of water is added to mix, and 0.01 times the mass of the pumpkin seed powder is added with neutral lipase under stirring at 50°C, treated for 0.5h, vacuum filtered, the filter residue is collected, and dried at 80°C to obtain defatted pumpkin seed powder;

[0037] S2. Steaming; put the strips of red taro and millet into a steamer and steam for 30 minutes, cool down and set aside;

[0038] S3. Preparation: According to the formula, the steamed red taro strips, millet and 2 / 3 of pure water are put into a beater, beaten for 18 minutes, and then crushed in an ultrasonic crusher with an ultrasonic frequency of 45Hz for 25 minutes to obtain a slurry; the pumpkin seed powder is added to a homogenizer, and an appropriate amount of pure water is added. The temperature is 55°C, the pressure is 10MPa, and the homogenization is carried out for 0.4h, the pressure is 20MPa, and the homogenization is carried out for 0.4h, the pressure is 30MPa, and the homogenization is carried out for 0.4h, and the pressure is 40MPa, and the homogenization is carried out for 0.4h to obtain a homogenous material; the slurry and the homogenous material are mixed evenly, and put into the homogenizer again, and the temperature is 55°C, the pressure is 40MPa, and the homogenization is carried out for 0.2h, the pressure is 30MPa, and the homogenization is carried out for 0.2h, the pressure is 20MPa, and the homogenization is carried out for 0.2h, and the pressure is 10MPa. a. Homogenize for 0.2h to obtain a mixed solution for use; mix the composite bacteria, the remaining purified water and maltitol evenly, and acclimate at 40°C for 7h to obtain an acclimatized bacterial solution;

[0039] S4. Inoculation: Inoculate the acclimated bacterial solution into the mixture at room temperature and stir evenly to obtain an inoculum;

[0040] S5. Packaging: filling the inoculum into bottled containers and sealing and packaging them separately, wherein the bottled containers are pre-filled with sterile nitrogen;

[0041] S6. Fermentation: The packaged bottled container is placed in a constant temperature incubator at 42±2°C for 6 hours to obtain fermented yogurt;

[0042] S7. Post-ripening: transfer the fermented yogurt to 5°C for post-ripening for 12 hours to obtain the finished product of red taro yogurt.

[0043] Example 2

[0044] A red taro yogurt comprises the following raw material components based on 1000 parts by weight of the yogurt: 400 parts of red taro strips, 50 parts of millet, 30 parts of pumpkin seed powder, 464 parts of purified water, 50 parts of maltitol and 6 parts of composite bacteria.

[0045] The composite bacteria is a mixed bacteria with a mass ratio of 1:1:1:1:1:1:1:1 of Lactobacillus bulgaricus, Streptococcus thermophilus, Lactobacillus acidophilus, Lactobacillus plantarum, Lactococcus lactis, Bifidobacterium longum and Lactobacillus rhamnosus, and the total number of viable bacteria is greater than 1×10 8 cfu / g;

[0046] The preparation method comprises the following steps:

[0047] S1. Raw material pretreatment: freshly picked red taro is washed, peeled, and cut into strips for later use; pumpkin seeds are shelled, fried, and crushed for later use; after the pumpkin seeds are crushed, 0.8 times the volume of water is added to mix, and 0.005 times the mass of the pumpkin seed powder is added with neutral lipase at 53°C under stirring, and the mixture is treated for 0.8h, vacuum filtered, and the filter residue is collected and dried at 75°C to obtain defatted pumpkin seed powder;

[0048] S2. Steaming; put the strips of red taro and millet into a steamer and steam for 40 minutes, cool down and set aside;

[0049] S3. Preparation: According to the formula, the steamed red taro strips, millet and 2 / 3 of pure water are put into a beater, beaten for 15 minutes, and then crushed in an ultrasonic crusher with an ultrasonic frequency of 40Hz for 25 minutes to obtain a slurry; the pumpkin seed powder is added to a homogenizer, and an appropriate amount of pure water is added. The temperature is 60°C, the pressure is 10MP a, and the homogenization is carried out for 0.5h, the pressure is 20MP a, and the homogenization is carried out for 0.5h, the pressure is 30MP a, and the homogenization is carried out for 0.5h, and the pressure is 40MP a, and the homogenization is carried out for 0.5h to obtain a homogenous material; the slurry and the homogenous material are mixed evenly, and put into the homogenizer again, and the temperature is 6°C, the pressure is 40MP a, and the homogenization is carried out for 0.15h, the pressure is 30MP a, and the homogenization is carried out for 0.15h, the pressure is 20MP a, and the homogenization is carried out for 0.15h, and the pressure is 10MP a, and the homogenization is carried out for 0.15h. a. Homogenize for 0.15h to obtain a mixed solution for use; mix the composite bacteria, the remaining purified water, and the food additives evenly, and acclimate at 42°C for 6h to obtain an acclimatized bacterial solution;

[0050] S4. Inoculation: Inoculate the acclimated bacterial solution into the mixture at room temperature and stir evenly to obtain an inoculum;

[0051] S5. Packaging: filling the inoculum into bottled containers and sealing and packaging them separately, wherein the bottled containers are pre-filled with sterile nitrogen;

[0052] S6. Fermentation: Place the packaged bottled container in a constant temperature incubator at 42±2°C for 4 hours to obtain fermented yogurt;

[0053] S7. Post-ripening: transfer the fermented yogurt to 6°C for post-ripening for 10 hours to obtain the finished product of red taro yogurt.

[0054] Example 3

[0055] A red taro yogurt comprises the following raw material components based on 1000 parts by weight of the yogurt: 350 parts of red taro strips, 80 parts of millet, 20 parts of pumpkin seed powder, 470 parts of purified water, 75 parts of maltitol and 5 parts of composite bacteria.

[0056] The composite bacteria is a mixture of Lactobacillus bulgaricus, Streptococcus thermophilus, Lactobacillus plantarum, Lactococcus lactis, Lactobacillus casei, and Bifidobacterium lactis in a mass ratio of 1:1:1:1:1:1, and the total number of viable bacteria is greater than 1×10 8 cfu / g;

[0057] The preparation method comprises the following steps:

[0058] S1. Raw material pretreatment: freshly picked red taro is washed, peeled, and cut into strips for later use; pumpkin seeds are shelled, fried, and crushed for later use; after the pumpkin seeds are crushed, 0.5 times the volume of water is added to mix, and 0.001 times the mass of the pumpkin seed powder is added with neutral lipase under stirring at 55°C, treated for 1h, vacuum filtered, and the filter residue is collected and dried at 70°C to obtain defatted pumpkin seed powder;

[0059] S2. Steaming; put the strips of red taro and millet into a steamer and steam for 20 minutes, cool down and set aside;

[0060] S3. Preparation: According to the formula, the steamed red taro strips, millet and 2 / 3 of pure water are put into a beater, beaten for 20 minutes, and then crushed in an ultrasonic crusher with an ultrasonic frequency of 50 Hz for 20 minutes to obtain a slurry; the pumpkin seed powder is added to a homogenizer, and an appropriate amount of pure water is added. The temperature is 50°C and the pressure is 10MP a, homogenized for 0.3h, the pressure is 20MP a, homogenized for 0.3h, the pressure is 30MP a, homogenized for 0.3h, the pressure is 40MP a, homogenized for 0.4h, and a homogenized material is obtained; the slurry and the homogenized material are mixed evenly, and put into the homogenizer again, and the temperature is 50°C and the pressure is 40MP a, homogenized for 0.2h, the pressure is 30MP a, homogenized for 0.2h, the pressure is 20MP a, homogenized for 0.2h, the pressure is 10MP a, homogenized for 0.2h, the pressure is 10MP a, homogenized for 0.2h, the pressure is 10MP a, homogenized for 0.2h a. Homogenize for 0.2h to obtain a mixed solution for use; mix the composite bacteria, the remaining purified water, and the food additives evenly, and acclimate at 37°C for 8h to obtain an acclimatized bacterial solution;

[0061] S4. Inoculation: Inoculate the acclimated bacterial solution into the mixture at room temperature and stir evenly to obtain an inoculum;

[0062] S5. Packaging: filling the inoculum into bottled containers and sealing and packaging them separately, wherein the bottled containers are pre-filled with sterile nitrogen;

[0063] S6. Fermentation: placing the packaged bottled container in a constant temperature incubator at 42±2°C for 8 hours to obtain fermented yogurt;

[0064] S7. Post-ripening: transfer the fermented yogurt to 4°C for post-ripening for 15 hours to obtain the finished product of red taro yogurt.

[0065] Comparative Example 1

[0066] A red taro sprout yogurt is different from Example 1 in that millet is not added, and an equal amount of red taro sprout strips are used instead, and the other parts are the same as Example 1.

[0067] Comparative Example 2

[0068] A red taro sprout yogurt is different from Example 1 in that pumpkin seed powder is not added, and an equal amount of red taro sprout strips are used instead, and the other parts are the same as Example 1.

[0069] Comparative Example 3

[0070] A red taro sprout yogurt is different from Example 1 in that millet and pumpkin seed powder are not added, and an equal amount of red taro sprout strips are used instead, and the rest is the same as Example 1.

[0071] Comparative Example 4

[0072] A red taro yogurt is different from Example 1 in that pumpkin seed powder is not treated with neutral lipase, and the rest is the same as Example 1.

[0073] Comparative Example 5

[0074] A red taro yogurt, which is different from Example 1 in that in S3 preparation, ultrasonic crushing is no longer performed after beating, and the rest is the same as Example 1.

[0075] Comparative Example 6

[0076] A red taro yogurt comprises the following raw material components based on 1000 parts by weight of the yogurt: 300 parts of red taro strips, 100 parts of millet, 50 parts of pumpkin seed powder, 466 parts of purified water, 80 parts of maltitol and 4 parts of composite bacteria.

[0077] The composite bacteria is a mixed bacteria of Lactobacillus bulgaricus, Streptococcus thermophilus, Lactobacillus plantarum, Lactococcus lactis, Lactobacillus casei, Bifidobacterium lactis, and Lactobacillus rhamnosus in a mass ratio of 1:1:1:1:1:1:1, and the total number of viable bacteria is greater than 1×10 8 cfu / g;

[0078] The preparation method comprises the following steps:

[0079] S1. Raw material pretreatment: freshly picked red taro is washed, peeled, and cut into strips for later use; pumpkin seeds are shelled, fried, and crushed for later use; after the pumpkin seeds are crushed, 1 volume of water is added to mix, and 0.01 times the mass of the pumpkin seed powder is added with neutral lipase under stirring at 50°C, treated for 0.5h, vacuum filtered, the filter residue is collected, and dried at 80°C to obtain defatted pumpkin seed powder;

[0080] S2. Steaming; put the strips of red taro and millet into a steamer and steam for 30 minutes, cool down and set aside;

[0081] S3. Preparation: According to the formula, the cooked red taro strips, millet, and 2 / 3 of the pure water are put into a beater, beaten for 18 minutes, and then crushed in an ultrasonic crusher with an ultrasonic frequency of 45Hz for 25 minutes to obtain a slurry; the slurry and pumpkin seed powder are added to a homogenizer, and the temperature is 55°C, the pressure is 40MP a, homogenized for 0.2h, the pressure is 30MP a, homogenized for 0.2h, the pressure is 20MP a, homogenized for 0.2h, the pressure is 10MP a, homogenized for 0.2h, and the mixed solution is prepared; the composite bacteria, the remaining pure water, and maltitol are mixed evenly, and placed at a temperature of 40°C for 7h to obtain a domesticated bacterial solution;

[0082] S4. Inoculation: Inoculate the acclimated bacterial solution into the mixture at room temperature and stir evenly to obtain an inoculum;

[0083] S5. Packaging: filling the inoculum into bottled containers and sealing and packaging them separately, wherein the bottled containers are pre-filled with sterile nitrogen;

[0084] S6. Fermentation: The packaged bottled container is placed in a constant temperature incubator at 42±2°C for 6 hours to obtain fermented yogurt;

[0085] S7. Post-ripening: transfer the fermented yogurt to 5°C for post-ripening for 12 hours to obtain the finished product of red taro yogurt.

[0086] Comparative Example 7

[0087] A red taro yogurt comprises the following raw material components based on 1000 parts by weight of the yogurt: 300 parts of red taro strips, 100 parts of millet, 50 parts of pumpkin seed powder, 466 parts of purified water, 80 parts of maltitol and 4 parts of composite bacteria.

[0088] The composite bacteria is a mixed bacteria of Lactobacillus bulgaricus, Streptococcus thermophilus, Lactobacillus plantarum, Lactococcus lactis, Lactobacillus casei, Bifidobacterium lactis, and Lactobacillus rhamnosus in a mass ratio of 1:1:1:1:1:1:1, and the total number of viable bacteria is greater than 1×10 8 cfu / g;

[0089] The preparation method comprises the following steps:

[0090] S1. Raw material pretreatment: freshly picked red taro is washed, peeled, and cut into strips for later use; pumpkin seeds are shelled, fried, and crushed for later use; after the pumpkin seeds are crushed, 1 volume of water is added to mix, and 0.01 times the mass of the pumpkin seed powder is added with neutral lipase under stirring at 50°C, treated for 0.5h, vacuum filtered, the filter residue is collected, and dried at 80°C to obtain defatted pumpkin seed powder;

[0091] S2. Steaming; put the strips of red taro and millet into a steamer and steam for 30 minutes, cool down and set aside;

[0092] S3. Preparation: According to the formula, the cooked red taro strips, millet, and 2 / 3 of the pure water are put into a beater, beaten for 18 minutes, and then crushed in an ultrasonic crusher with an ultrasonic frequency of 45Hz for 25 minutes to obtain a slurry; the pumpkin seed powder is added to a homogenizer, an appropriate amount of pure water is added, the temperature is 55°C, the pressure is 40MP a, and the homogenization is performed for 1.6 hours to obtain a homogenous material; the slurry and the homogenized material are mixed evenly, and the mixture is put into the homogenizer again, and the temperature is 55°C, the pressure is 10MP a, and the homogenization is performed for 0.8 hours to obtain a mixed solution for standby use; the composite bacteria, the remaining pure water, and maltitol are mixed evenly, and placed at a temperature of 40°C for 7 hours to obtain an acclimated bacterial solution;

[0093] S4. Inoculation: Inoculate the acclimated bacterial solution into the mixture at room temperature and stir evenly to obtain an inoculum;

[0094] S5. Packaging: filling the inoculum into bottled containers and sealing and packaging them separately, wherein the bottled containers are pre-filled with sterile nitrogen;

[0095] S6. Fermentation: The packaged bottled container is placed in a constant temperature incubator at 42±2°C for 6 hours to obtain fermented yogurt;

[0096] S7. Post-ripening: transfer the fermented yogurt to 5°C for post-ripening for 12 hours to obtain the finished product of red taro yogurt.

[0097] Comparative Example 8

[0098] A red taro yogurt comprises the following raw material components based on 1000 parts by weight of the yogurt: 300 parts of red taro strips, 100 parts of millet, 50 parts of pumpkin seed powder, 466 parts of purified water, 80 parts of maltitol and 4 parts of composite bacteria.

[0099] The composite bacteria is a mixed bacteria of Lactobacillus bulgaricus, Streptococcus thermophilus, Lactobacillus plantarum, Lactococcus lactis, Lactobacillus casei, Bifidobacterium lactis, and Lactobacillus rhamnosus in a mass ratio of 1:1:1:1:1:1:1, and the total number of viable bacteria is greater than 1×10 8 cfu / g;

[0100] The preparation method comprises the following steps:

[0101] S1. Raw material pretreatment: freshly picked red taro is washed, peeled, and cut into strips for later use; pumpkin seeds are shelled, fried, and crushed for later use; after the pumpkin seeds are crushed, 1 volume of water is added to mix, and 0.01 times the mass of the pumpkin seed powder is added with neutral lipase under stirring at 50°C, treated for 0.5h, vacuum filtered, the filter residue is collected, and dried at 80°C to obtain defatted pumpkin seed powder;

[0102] S2. Steaming; put the strips of red taro and millet into a steamer and steam for 30 minutes, cool down and set aside;

[0103] S3. Preparation: According to the formula, the cooked red taro strips, millet, pumpkin seed powder, maltitol and purified water were put into a beater and beaten for 18 minutes to obtain a slurry;

[0104] S4. Inoculation: Inoculate the composite bacterial solution into the slurry at room temperature and stir evenly to obtain an inoculum;

[0105] S5. Packaging: filling the inoculum into bottled containers and sealing and packaging them separately, wherein the bottled containers are pre-filled with sterile nitrogen;

[0106] S6. Fermentation: The packaged bottled container is placed in a constant temperature incubator at 42±2°C for 6 hours to obtain fermented yogurt;

[0107] S7. Post-ripening: transfer the fermented yogurt to 5°C for post-ripening for 12 hours to obtain the finished product of red taro yogurt.

[0108] Test Example 1

[0109] The sensory evaluation, stability and nutritional components of the finished red taro yogurt prepared in Examples 1-3 and Comparative Examples 1-8 were tested, and the results are shown in Tables 1-4. Among them, the sensory evaluation is mainly based on the appearance color, flavor, smoothness, and consistency; the stability is to store the finished red taro yogurt at a low temperature of about 4°C for 7 days to test its stability; the nutritional components are tested according to relevant methods such as GB5009-2016, GB 28050-2011, GB 4789, etc.

[0110] Table 1 Sensory evaluation

[0111] Group Color Flavor Delicate Thin consistency Example 1 Creamy yellow white, uniform With taro fragrance, no odor Delicate and smooth Thicker, better shape retention Example 2 Creamy yellow white, uniform With taro fragrance, no odor Delicate and smooth Thicker, better shape retention Example 3 Creamy yellow white, uniform With taro fragrance, no odor Delicate and smooth Thicker, better shape retention Comparative Example 1 Milky white, uniform With taro fragrance, no odor Delicate and smooth Thicker, better shape retention Comparative Example 2 Creamy yellow white, uniform With taro fragrance, no odor Delicate and smooth Thicker, better shape retention Comparative Example 3 Milky white, uniform With taro fragrance, no odor Delicate and smooth Thicker, better shape retention Comparative Example 4 Creamy yellow white, uniform With taro fragrance, no odor Delicate and smooth Thicker, better shape retention Comparative Example 5 Creamy yellow white, uniform With taro fragrance, no odor Delicate and smooth Thicker, better shape retention Comparative Example 6 Creamy yellow white, more uniform With taro fragrance, no odor Not delicate and smooth enough Thicker, poor shape retention Comparative Example 7 Creamy yellow white, more uniform With taro fragrance, no odor Not delicate and smooth enough Thicker, poor shape retention Comparative Example 8 Creamy white, uneven Taro flavor is not strong enough Rough, grainy Thicker, poor shape retention

[0112] Table 2 Stability

[0113]

[0114]

[0115]

[0116] Table 3 Nutritional composition

[0117]

[0118] Table 4 Amino acid content (proportion of total amino acids)

[0119]

[0120]

[0121] It can be seen from the results in Tables 1-4 that the finished product of the taro yogurt prepared by the formula and preparation method of the present invention has good color, unique flavor, delicate and smooth taste, good stability, no protein water precipitation, fat floating, and stratification phenomenon, rich nutrition, especially uniform essential amino acid content, EAA / TAA is between 40.55-41.04%, EAA / NEAA is between 68.21-69.61%, and the number of lactic acid bacteria can meet the requirements of live bacteria yogurt.

[0122] In contrast to Example 1 and Comparative Examples 1-3, only millet or pumpkin seed powder was added. Although it had little effect on sensory evaluation and stability, and could increase the content of essential amino acids, especially tryptophan, to a certain extent, a single addition was not very ideal. When neither millet nor pumpkin seed powder was added, the essential amino acids were significantly lower, indicating that the addition of millet and pumpkin seed powder could effectively increase the content of essential amino acids (especially tryptophan) and improve the nutritional value.

[0123] Compared with Example 1 and Example 4, in Example 4, pumpkin seed powder was not defatted. Although it had no effect on sensory evaluation, its fat content was relatively high, and the oil would float during storage, resulting in poor stability.

[0124] Compared with Example 1 and Examples 5-7, Example 5 did not use ultrasonic treatment after pulping. Although it had no effect on the sensory evaluation, it had a certain effect on the stability and effective nutrients. In Example 6, only concentrated homogenization was performed once, and in Example 7, a single pressure was used for homogenization. Although it had little effect on the nutrients, it had a certain effect on the sensory evaluation and stability.

[0125] Compared with Example 1 and Example 8, in Example 8, all the raw materials were pulped at one time without separate treatment, and without ultrasonic crushing and homogenization. The product had a relatively rough sensory feel, poor shape retention, and poor taste. It was easy to stratify during storage and had poor dispersibility.

[0126] In summary, the red taro yogurt containing live bacteria prepared by the formula and preparation method of the present invention has good color, unique flavor, delicate and smooth taste, good stability, is rich in essential amino acids for the human body, and the amino acid pattern meets the requirements of the ideal protein pattern (amino acid pattern) recommended by FAO / WHO, and has high nutritional value.

[0127] Finally, it should be emphasized that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various changes and modifications. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing red taro yogurt, characterized in that: The yogurt is prepared from the following raw materials based on 1000 parts by weight: 300-400 parts of red taro strips, 50-100 parts of millet, 20-50 parts of pumpkin seed powder, 400-500 parts of purified water, 50-80 parts of food additives, and 4-6 parts of composite bacteria; the EAA / TAA ratio in the yogurt is between 39-42%, and the EAA / NEAA ratio is greater than 65%; The composite bacteria is a mixture of at least five of Lactobacillus bulgaricus, Streptococcus thermophilus, Lactobacillus acidophilus, Lactobacillus plantarum, Lactococcus lactis, Lactobacillus casei, Bifidobacterium lactis, Bifidobacterium longum, and Lactobacillus rhamnosus in any proportion, and must contain Streptococcus thermophilus, Lactobacillus plantarum, and Lactococcus lactis. The preparation method comprises the following steps: S1. Raw material pretreatment: freshly picked red taro is washed, peeled, and cut into strips for later use; pumpkin seeds are shelled, fried, and crushed for later use; the crushed pumpkin seeds are mixed with 0.5-1 times the volume of pure water, neutral lipase is added under stirring at 50-55°C, treated for 0.5-1h, vacuum filtered, the filter residue is collected, and dried at 70-80°C to obtain defatted pumpkin seed powder; S2. Steaming: Put the strips of red taro and millet into a steamer and steam for 20-40 minutes, cool down and set aside; S3. Preparation: According to the formula, the cooked red taro strips, millet, and 2 / 3 of pure water are put into a beater, beaten for 15-20 minutes, and then crushed in an ultrasonic crusher with an ultrasonic frequency of 40-50Hz for 20-30 minutes to obtain a slurry; the pumpkin seed powder is added to a homogenizer, an appropriate amount of pure water is added, and homogenized for 1-2 hours to obtain a homogenous material; the slurry and the homogenized material are mixed, and the mixture is put into the homogenizer again, homogenized for 0.5-1h, and a mixed solution is obtained for standby use; the complex The syncytium, the remaining purified water and the food additives are mixed evenly and placed at a temperature of 37-42° C. for acclimation to obtain an acclimated bacterial solution; the homogenizers are all sterile treated, and the homogenization conditions are: a pressure of 10-40 MPa and a temperature of 50-60° C., wherein the pressure is increased from 10 MPa to 40 MPa at an interval of 10 MPa for the first homogenization; and the pressure is reduced from 40 MPa to 10 MPa at an interval of 10 MPa for the second homogenization; S4. Inoculation: Inoculate the acclimated bacterial solution into the mixed solution at room temperature, stir evenly, and obtain an inoculum; S5. Packaging: Fill the inoculum into bottled containers and seal them separately; S6. Fermentation: Place the packaged bottled container in a constant temperature incubator at 42±2°C for 4-8 hours to obtain fermented yogurt; S7. Post-ripening: transfer the fermented yogurt to 4-6°C for post-ripening for 10-15h to obtain the finished product of red taro yogurt.

2. The method for preparing red taro yogurt according to claim 1, characterized in that: The total number of viable bacteria of the composite bacteria is greater than 1×10 8 cfu / g.

3. The method for preparing red taro yogurt according to claim 1, characterized in that: The food additive is maltitol.

4. The method for preparing red taro yogurt according to claim 1, characterized in that: The mass ratio of the added amount of the neutral lipase to the pumpkin seed powder is 0.002-0.01:

1.

5. The method for preparing red taro yogurt according to claim 1, characterized in that: In S3, the acclimation time is 6-8 hours; in S5, the bottled container is pre-filled with sterile nitrogen.

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