Method for preparing composite resistant starch set yoghurt with high storage stability and strong probiotic characteristics based on ternary system and application of composite resistant starch set yoghurt

Abstract

The invention provides an RS4-RS5-yoghourt ternary composite system, a corresponding composite resistant starch set-style yoghourt product, and a preparation method and application of the RS4-RS5-yoghourt ternary composite system and the corresponding composite resistant starch set-style yoghourt product. The composite resistant starch set yogurt based on the ternary system has the characteristics of high water binding capacity, storage stability, high probiotic content and the like. The ternary system provided by the invention can be respectively suitable for middle-aged and elderly people and teenagers through individual optimization of the proportion. The preparation method is simple and efficient, and the product is good in stability and has potential nutritional and healthy effects of improving intestinal functions, enhancing human immunity and the like.

Description

Technical Field

[0001] The invention belongs to the field of fermented dairy products, and in particular relates to a method for preparing a composite resistant starch coagulated yogurt with high storage stability and strong probiotic properties based on a ternary system and an application thereof. Background Art

[0002] As people's health awareness continues to increase, the status of dairy products in the residents' dietary structure has been significantly improved. As one of the fastest-growing categories of dairy products, yogurt is widely favored by consumers for its unique flavor and rich nutrients.

[0003] Traditional set yogurt has a single nutritional component, and adding dietary fiber to set yogurt is an effective way to improve the nutritional value of yogurt. Currently, the dietary fibers added on the market include polydextrose, oligofructose, inulin, etc. However, the addition of these dietary fibers requires the addition of additional food additives such as stabilizers and emulsifiers to improve the storage stability of yogurt. In addition, the addition of these dietary fibers will cause the problem of excessive acidification of yogurt in the later stage of fermentation, affecting the quality and flavor of yogurt. Therefore, how to obtain a new type of dietary fiber that can simultaneously improve the storage stability of yogurt, improve the quality of yogurt and its nutritional value without affecting the taste and flavor has become a key technical bottleneck in the current breakthrough of yogurt product research and development.

[0004] Different types of resistant starch have different functional properties. As a new type of dietary fiber, resistant starch can escape the digestion of amylase in the small intestine and enter the colon, where it is degraded by intestinal bacteria to produce short-chain fatty acids. Among them, chemically modified starch (RS4) usually introduces functional groups into starch molecules. The introduction of these functional groups not only significantly changes the physical and chemical properties of starch, but also hinders amylase hydrolysis. Cross-linked and acetylated modified starch can also significantly increase the content of propionic acid. Starch-lipid complex (RS5) has good enzyme resistance and prebiotic properties due to its unique structure, and can promote the proliferation of butyrate-producing bacteria. In addition, RS5 can also be used as a fat mimetic in dairy products and baked products to improve the nutritional and health quality of food.

[0005] Different types of resistant starch have their own advantages and disadvantages. At present, there are few reports on composite resistant starch that has the dual characteristics of chemically modified starch (RS4) and starch-lipid complex (RS5), and there is no record of its application in the field of set yogurt.

[0006] Some of the terms / vocabulary used in this invention:

[0007] RS4: chemically modified starch;

[0008] RS5: Starch-lipid complexes are divided into type I and type II complexes based on their thermodynamic properties.

[0009] V-type crystal structure: Amylose forms a single helical structure, and lipids are inserted into its cavity through non-covalent bonds. The single helical structure containing lipids is stacked into lamellar crystals. These lamellar crystals and amorphous regions are together wrapped into micron-sized spherulites or rod-like structures. This structure is called V-type crystal structure.

[0010] Type I complex: Type I complex rapidly nucleates and forms at a relatively low complexing temperature (<60°C), and its dissociation temperature is below 100°C.

[0011] Type II complex: Type II complex is formed at higher complexation temperature (>90°C) and the dissociation temperature is above 100°C.

[0012] Complex interaction: The complex process in which the starch chain structure and the lipid structure interact to form complex resistant starch. Summary of the invention

[0013] The main purpose of the present invention is to obtain a set yogurt with high stability and good sensory quality during storage, that is, a composite resistant starch set yogurt with high storage stability and strong probiotic properties.

[0014] The invention also provides a preparation method and application of the composite resistant starch coagulated yogurt.

[0015] The present invention provides a ternary composite system of "chemically modified starch RS4-starch-lipid complex RS5-yogurt". In the present invention, the applicant creatively introduces a composite resistant starch having the dual characteristics of chemically modified starch (RS4) and starch-lipid complex (RS5) into the production of coagulated yogurt to form a RS4-RS5-yogurt ternary composite system, which not only reduces the undesirable phenomenon of yogurt whey precipitation, significantly improves the taste quality and storage stability of yogurt, but also enriches the nutritional value of yogurt and increases the production of short-chain fatty acids in yogurt, especially propionic acid and butyric acid.

[0016] To achieve the above object, the present invention provides a coagulated yogurt containing composite resistant starch, which is mainly composed of the following raw materials: 80-99% (w / w) whole milk, 1-10% (w / w) white sugar, 0.5-10% (w / w) composite resistant starch, and 0.01-0.5% (w / w) starter; wherein the composite resistant starch is mainly composed of RS4 and RS5 in a composite interaction;

[0017] Furthermore, the yogurt is made from the following raw materials: 85-95% (w / w) whole milk, 5-9% (w / w) white sugar, 1-8% (w / w) composite resistant starch, and 0.05-0.2% (w / w) starter;

[0018] Furthermore, the yogurt is made from the following raw materials: 88-93% (w / w) whole milk, 6-8% (w / w) white sugar, 2-5% (w / w) composite resistant starch, and 0.1% (w / w) starter;

[0019] Furthermore, whole milk 88.9-91.9% (w / w), white sugar 7% (w / w), complex resistant starch 1-4% (w / w), starter 0.1% (w / w). The complex resistant starch is composed of RS4 and RS5 in a complex interaction;

[0020] Preferably, the yogurt is made from the following raw materials: 88.9-91.9% (w / w) whole milk, 7% (w / w) white sugar, 4% (w / w) composite resistant starch, and 0.1% (w / w) starter. The yogurt composition containing 4% (w / w) composite resistant starch has a lower hardness and is suitable for middle-aged and elderly people;

[0021] Preferably, the composite resistant starch coagulated yogurt according to claim 3 is characterized in that the yogurt is made from the following raw materials: 88.9-91.9% (w / w) whole milk, 7% (w / w) white sugar, 2% (w / w) composite resistant starch, and 0.1% (w / w) starter. The yogurt composition containing 2% (w / w) composite resistant starch has a high hardness and is suitable for teenagers.

[0022] The composite resistant starch coagulated yogurt of the present invention is characterized in that the composite resistant starch is prepared by a method comprising the following steps:

[0023] A certain amount of corn starch and deionized water are prepared into a starch suspension, which is heated at 68°C for 5 minutes, freeze-dried, and ground to obtain gelatinized starch for use. The gelatinized starch is mixed with deionized water to prepare a starch suspension with a concentration of 10% (w / w), and after adjusting the pH, octenyl succinic anhydride (OSA) is added dropwise. After the reaction is completed, the sample is freeze-dried and recovered, and the RS4 is obtained after washing, volatilization, and grinding with anhydrous ethanol. The RS4 is resuspended in deionized water, diglyceride is added and mixed evenly, the starch-lipid suspension is heated and stirred, and then gradually cooled to 25°C, and the sample is freeze-dried and recovered. The obtained sample is washed, volatilized, and ground to obtain the composite resistant starch.

[0024] The composite resistant starch coagulated yogurt of the present invention has the dual functional probiotic properties of RS4 and RS5, and has a V-type crystal structure with a crystallinity range of 19.1-21.1%. The main content of the added composite resistant starch is type I complex, and T PIn the range of 90-110°C, at 85°C, the swelling power of composite resistant starch (20-30%) was higher than that of gelatinized starch (9.0%).

[0025] The composite resistant starch coagulated yogurt of the present invention mainly comprises RS4 and RS5 in a composite interaction. RS4 has an A-type crystal structure, and compared with the infrared spectrum of natural starch, the -1 and 1726cm -1 RS5 has a V-type crystal structure. Compared with the infrared spectrum of natural starch, the peak at 1710 cm -1 and 2857cm -1 A new characteristic peak appears.

[0026] The coagulated yogurt containing the composite resistant starch of the present invention is a milky white viscous solid with good taste and fine texture, and does not need to add other food additives. The addition of the composite resistant starch improves the water holding capacity and storage stability of the yogurt, and increases the content of short-chain fatty acids in the yogurt, especially propionic acid and butyric acid.

[0027] The coagulated yogurt of the composite resistant starch of the present invention is prepared by the following method:

[0028] Preheating and mixing stage: After the milk is preheated, add white sugar and complex resistant starch and mix the three evenly;

[0029] Heating sterilization stage: sterilize at 80-85℃ for 20-30min;

[0030] Inoculation and fermentation stage: after the temperature is cooled, a mixed strain (a mixture of thermophilic Streptococcus, Bulgarian Lactobacillus, Lactococcus lactis and Bifidobacterium) is added as a starter, and the inoculation amount of the mixed strain is 0.1-0.5% (w / w). The inoculated milk is placed at a temperature of 40-44°C for fermentation;

[0031] Cooling and ripening stage: Store the fermented yogurt at 4°C for 20-24 hours.

[0032] Furthermore, the preparation method of the coagulated yogurt of the composite resistant starch of the present invention is as follows:

[0033] (1) After preheating the whole milk, add white sugar and (1-4%, w / w) composite resistant starch, and stir evenly; heat and sterilize at 80-85° C. for 20-30 minutes;

[0034] (2) When the mixture is cooled to 40-44° C., a mixed bacterial strain (a mixture of thermophilic Streptococcus, Bulgarian Lactobacillus, Lactococcus lactis and Bifidobacterium, with a ratio of 10:3:1:1 to 1:1:1:1) is added as a starter, the inoculation amount of the mixed bacterial strain is 0.1-0.5% (w / w), and the mixture is fermented for 6-10 hours; and the mixture is cooled and ripened at 4° C. for 20-24 hours.

[0035] Furthermore, the preparation method of the coagulated yogurt of the composite resistant starch of the present invention is as follows:

[0036] (1) Preheat the whole milk, add white sugar and composite resistant starch, and mix the three evenly; then raise the temperature to 80-85°C for sterilization for 20-30 minutes;

[0037] (2) Cooling the milk obtained in step (1) to 40-44° C., adding a mixed bacterial strain (a mixture of thermophilic Streptococcus, Bulgarian Lactobacillus, Lactococcus lactis and Bifidobacterium, the ratio of the four bacteria being 10:3:1:1 to 1:1:1:1) as a starter, the inoculation amount of the mixed bacterial strain being 0.1-0.5% (w / w), then fermenting at a temperature of 40-44° C., and cooling the fermented yogurt at 4° C. for post-ripening.

[0038] The composite resistant starch in the above preparation method has a V-type crystal structure with a crystallinity range of 19.1-21.1%. The main content of the added composite resistant starch is type I complex, and T p In the range of 90-110°C, at 85°C, the swelling power of composite resistant starch (20-30%) was higher than that of gelatinized starch (9.0%).

[0039] In the above preparation method, in step (1), whole milk is heated to 60°C, white sugar and composite resistant starch are gradually added at 600 rpm, and after stirring for 30 minutes, the milk is heated at 85°C for 20 minutes.

[0040] The above preparation method, wherein in step (2), when the milk is cooled to 43°C, 0.1% (w / w) of a starter (the mass ratio of thermophilic Streptococcus, Lactobacillus bulgaricus, Lactobacillus lactis and Bifidobacterium is 10:3:1:1 to 1:1:1:1) is added, and the number of viable bacteria is ≥1×10 7 CFU / g), stirred at 600 rpm for 10 min, and then fermented for 7 h; the fermented yogurt was post-ripened at 4 °C for 24 h.

[0041] Furthermore, the composite resistant starch added in step (1) has a V-type crystal structure, mainly exhibits a type I complex, and has a higher swelling power than gelatinized starch at 60° C. and 85° C., respectively.

[0042] Furthermore, the composite resistant starch added in the step (1) is a white solid powder with no irritating odor, and is prepared by a hydrothermal method, that is, octenyl succinate starch ester and palmitic acid diglyceride are mixed to form a suspension, heated in a water bath, cooled, freeze-dried for 24 hours, and then crushed and sieved to obtain the composite resistant starch.

[0043] The composite resistant starch coagulated yogurt provided by the present invention has the following positive effects:

[0044] (1) RS4-RS5-yogurt ternary composite system has strong stability and water holding capacity, giving yogurt a good taste quality, and the demand for technical iteration is clear. The water holding capacity of yogurt with added composite resistant starch is 80-91%, which is higher than the water holding capacity of traditional coagulated yogurt (70%) and the water holding capacity of yogurt with added polydextrose (76%). After 21 days of storage, the water holding capacity of yogurt with added composite resistant starch (69-87%) is still higher than the water holding capacity of traditional coagulated yogurt (59%) and the water holding capacity of yogurt with added polydextrose (68%). The significant improvement in water holding capacity can effectively reduce the adverse phenomenon of whey precipitation, which helps to improve the quality and stability of yogurt. In addition, the addition of composite resistant starch improves the sensory evaluation of yogurt and is easily recognized and accepted by consumers; it meets the requirements of yogurt.

[0045] (6) High appearance index score. The yogurt containing the composite resistant starch of the present invention has a higher yogurt smoothness score (7.9-9.0) than the traditional yogurt (6.8), and a higher consistency score (7.0-9.3) than the traditional yogurt (5.9).

[0046] (7) Multiple advantages and good commercial prospects. The composite resistant starch coagulated yogurt of the present invention has multiple characteristics such as high storage stability and strong prebiotic properties. On the one hand, it has high storage stability, which improves food safety; on the other hand, it has the prebiotic function of potentially improving the intestinal microecological environment, which can better meet the needs of modern people for nutritious and healthy food. The addition of composite resistant starch in the method of the present invention has a diverse effect on yogurt, and yogurt products of different qualities can be obtained to suit different consumer groups, thereby achieving dynamic control of product characteristics and meeting the diversified needs of the market. The composite resistant starch coagulated yogurt of the present invention has a good commercial future.

[0047] In summary, the present invention provides a "RS4-RS5-yogurt" ternary composite system, a corresponding composite resistant starch coagulated yogurt product, and a preparation method and application thereof. The composite resistant starch coagulated yogurt based on the ternary system has multiple characteristics such as high storage stability, high water holding capacity, and high probiotic content. The ternary system of the present invention can be suitable for middle-aged and elderly people and young people through personalized optimization of the ratio. Among them, the yogurt with 4% (w / w) composite resistant starch added has a lower hardness and is suitable for middle-aged and elderly people, and the yogurt with 2% (w / w) composite resistant starch added has a higher hardness and is suitable for young people. The preparation method of the coagulated yogurt is simple and efficient, the product has good stability, and has potential nutritional and health effects such as improving intestinal function and enhancing human immunity. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 (A / B / C) are respectively the pH value, acidity and water holding capacity of Examples 1-3 and Comparative Examples 1-2 during storage Figure 2 (A / B / C / D / E) are the static rheology of Examples 1-3 and Comparative Examples 1-2 respectively. Figure 3 (A / B / C / D / E) are the dynamic rheological properties of Examples 1-3 and Comparative Examples 1-2, respectively. Figure 4 (A / B / C / D) are the short-chain fatty acid contents of Examples 1-3 and Comparative Examples 1-2 respectively Figure 5 Quantitative analysis of sensory evaluation results of Examples 1-3 and Comparative Examples 1-2 Figure 6 (A / B) are the X-ray diffraction pattern and swelling power of composite resistant starch, respectively. DETAILED DESCRIPTION

[0054] The technical solutions in the embodiments of the present invention are described clearly and completely below, but the present invention is not limited to the embodiments described here. The experimental methods in the following embodiments that do not specify specific conditions are selected according to conventional methods and conditions, or according to the product specifications. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0055] The raw and auxiliary materials in the following examples, unless otherwise specified, can be purchased from the market.

[0056] Example 1 Preparation of a composite resistant starch coagulated yogurt

[0057] (1) This embodiment provides a set yogurt containing composite resistant starch, which is composed of the following raw materials: 91.9% whole milk, 7% white sugar, 1% composite resistant starch, and 0.1% mixed bacteria (including thermophilic Streptococcus, bulgaricus, Lactococcus lactis and bifidobacterium mixed bacteria, the four being in a ratio of 1:1:1:1).

[0058] (2) Preparation method of composite resistant starch: ① Preparation of gelatinized starch: a certain amount of corn starch and deionized water are prepared into a starch suspension, which is then heated and freeze-dried to obtain gelatinized starch; ② Preparation of RS4: gelatinized starch is mixed with deionized water to prepare a starch suspension with a concentration of 10% (w / w), and after adjusting the pH, octenyl succinic anhydride (OSA) is added dropwise. After the reaction is completed, the sample is freeze-dried and recovered, and then washed with anhydrous ethanol, evaporated, and ground to obtain RS4; ③ Preparation of composite resistant starch: RS4 is resuspended in deionized water, diglyceride is added and mixed evenly, the starch-lipid suspension is heated and stirred, and then gradually cooled to 25°C, and the sample is freeze-dried and recovered. The obtained sample is washed, evaporated, and ground to obtain composite resistant starch.

[0059] (3) The processing and preparation method of the coagulated yogurt is as follows: ① preheating and mixing stage, after preheating the whole milk, add white sugar and complex resistant starch, and mix the three evenly; ② heating and sterilization stage, sterilize at 85°C for 20 minutes; ③ inoculation and fermentation stage, wait for the temperature to cool to 43°C, inoculate 0.1% (w / w) mixed bacteria, and ferment at this temperature for 7 hours; ④ cooling and ripening stage, store the fermented yogurt at 4°C for 24 hours.

[0060] Example 2 Preparation of a composite resistant starch coagulated yogurt

[0061] (1) This embodiment provides a set yogurt containing composite resistant starch, which is composed of the following raw materials: 90.9% whole milk, 7% white sugar, 2% composite resistant starch, and 0.1% mixed bacteria (including thermophilic Streptococcus, bulgaricus, Lactococcus lactis and bifidobacterium mixed bacteria, the four being in a ratio of 1:1:1:1).

[0062] (2) The processing and preparation method is the same as that in Example 1.

[0063] Example 3 Preparation of a composite resistant starch coagulated yogurt

[0064] (1) This embodiment provides a set yogurt containing composite resistant starch, which is composed of the following raw materials: 88.9% whole milk, 7% white sugar, 4% composite resistant starch, and 0.1% mixed bacteria (including thermophilic Streptococcus, bulgaricus, Lactococcus lactis and bifidobacterium mixed bacteria, the four being in a ratio of 1:1:1:1).

[0065] (2) The processing and preparation method is the same as that in Example 1.

[0066] Example 4 Preparation of a composite resistant starch coagulated yogurt

[0067] (1) This embodiment provides a set yogurt containing composite resistant starch, which is composed of the following raw materials: 86.9% whole milk, 7% white sugar, 6% composite resistant starch, and 0.1% mixed bacteria (including thermophilic Streptococcus, bulgaricus, Lactococcus lactis and bifidobacterium mixed bacteria, the four being in a ratio of 1:1:1:1).

[0068] (2) The processing and preparation method is the same as that in Example 1.

[0069] Example 5 Preparation of a composite resistant starch coagulated yogurt

[0070] (1) This embodiment provides a set yogurt containing composite resistant starch, which is composed of the following raw materials: 91.9% whole milk, 7% white sugar, 1% composite resistant starch, and 0.1% mixed bacteria (including thermophilic Streptococcus, bulgaricus, Lactococcus lactis and bifidobacterium mixed bacteria, the ratio of the four being 10:3:1:1).

[0071] (2) The processing and preparation method is the same as that in Example 1.

[0072] Example 6 Preparation of a composite resistant starch coagulated yogurt

[0073] (1) This embodiment provides a set yogurt containing composite resistant starch, which is composed of the following raw materials: 91.9% whole milk, 7% white sugar, 2% composite resistant starch, and 0.1% mixed bacteria (including thermophilic Streptococcus, bulgaricus, Lactococcus lactis and bifidobacterium mixed bacteria, the ratio of the four being 10:3:1:1).

[0074] (2) The processing and preparation method is the same as that in Example 1.

[0075] Example 7 Preparation of a composite resistant starch coagulated yogurt

[0076] (1) This embodiment provides a set yogurt containing composite resistant starch, which is composed of the following raw materials: 88.9% whole milk, 7% white sugar, 4% composite resistant starch, and 0.1% mixed bacteria (including thermophilic Streptococcus, bulgaricus, Lactococcus lactis and bifidobacterium mixed bacteria, the ratio of the four being 10:3:1:1).

[0077] (2) The processing and preparation method is the same as that in Example 1.

[0078] Example 8 Preparation of a composite resistant starch coagulated yogurt

[0079] (1) This embodiment provides a set yogurt containing composite resistant starch, which is composed of the following raw materials: 86.9% whole milk, 7% white sugar, 6% composite resistant starch, and 0.1% mixed bacteria (including thermophilic Streptococcus, bulgaricus, Lactococcus lactis and bifidobacterium mixed bacteria, the ratio of the four being 10:3:1:1).

[0080] (2) The processing and preparation method is the same as that in Example 1.

[0081] Example 9 Preparation of a composite resistant starch coagulated yogurt

[0082] (1) This embodiment provides a set yogurt containing composite resistant starch, which is composed of the following raw materials: 91.9% whole milk, 7% white sugar, 1% composite resistant starch, and 0.1% mixed bacteria (including thermophilic Streptococcus, bulgaricus, Lactococcus lactis and bifidobacterium mixed bacteria, the ratio of the four being 6:2:1:1).

[0083] (2) The processing and preparation method is the same as that in Example 1.

[0084] Example 10 Preparation of a composite resistant starch coagulated yogurt

[0085] (1) This embodiment provides a set yogurt containing composite resistant starch, which is composed of the following raw materials: 91.9% whole milk, 7% white sugar, 2% composite resistant starch, and 0.1% mixed bacteria (including thermophilic Streptococcus, bulgaricus, Lactococcus lactis and bifidobacterium mixed bacteria, the ratio of the four is 6:2:1:1).

[0086] (2) The processing and preparation method is the same as that in Example 1.

[0087] Example 11 Preparation of a composite resistant starch coagulated yogurt

[0088] (1) This embodiment provides a set yogurt containing composite resistant starch, which is composed of the following raw materials: 88.9% whole milk, 7% white sugar, 4% composite resistant starch, and 0.1% mixed bacteria (including thermophilic Streptococcus, bulgaricus, Lactococcus lactis and bifidobacterium mixed bacteria, the ratio of the four being 6:2:1:1).

[0089] (2) The processing and preparation method is the same as that in Example 1.

[0090] Example 12 Preparation of a composite resistant starch coagulated yogurt

[0091] (1) This embodiment provides a set yogurt containing composite resistant starch, which is composed of the following raw materials: 86.9% whole milk, 7% white sugar, 6% composite resistant starch, and 0.1% mixed bacteria (including thermophilic Streptococcus, bulgaricus, Lactococcus lactis and bifidobacterium mixed bacteria, the ratio of the four being 6:2:1:1).

[0092] (2) The processing and preparation method is the same as that in Example 1.

[0093] Example 13 Preparation of a composite resistant starch coagulated yogurt

[0094] (1) This embodiment provides a set yogurt containing composite resistant starch, which is composed of the following raw materials: 80% whole milk, 10% white sugar, 9.5% composite resistant starch, and 0.5% mixed bacteria (including thermophilic Streptococcus, bulgaricus, Lactococcus lactis and bifidobacterium mixed bacteria, the four being in a ratio of 1:1:1:1).

[0095] (2) The processing and preparation method is the same as that in Example 1.

[0096] Example 14 Preparation of a composite resistant starch coagulated yogurt

[0097] (1) This embodiment provides a set yogurt containing composite resistant starch, which is composed of the following raw materials: 88.99% whole milk, 1% white sugar, 10% composite resistant starch, and 0.01% mixed bacteria (including thermophilic Streptococcus, bulgaricus, Lactococcus lactis and bifidobacterium mixed bacteria, the four being in a ratio of 1:1:1:1).

[0098] (2) The processing and preparation method is the same as that in Example 1.

[0099] Example 15 Preparation of a composite resistant starch coagulated yogurt

[0100] (1) This embodiment provides a set yogurt containing composite resistant starch, which is composed of the following raw materials: 98% whole milk, 1% white sugar, 0.5% composite resistant starch, and 0.5% mixed bacteria (including thermophilic Streptococcus, bulgaricus, Lactococcus lactis and bifidobacterium mixed bacteria, the four being in a ratio of 1:1:1:1).

[0101] (2) The processing and preparation method is the same as that in Example 1.

[0102] Comparative Example 1 Preparation of traditional coagulated yogurt

[0103] (1) This comparative example provides a method for preparing a traditional set-type yogurt, which is composed of the following raw materials: 100 mL of whole milk, 7 g of white sugar, and 0.1 g of a mixed strain (including thermophilic Streptococcus, bulgaricus, Lactococcus lactis and bifidobacterium mixed strains, the four of which are in a ratio of 1:1:1:1).

[0104] (2) The processing and preparation method is the same as that in Example 1.

[0105] Comparative Example 2 Preparation of Traditional Dietary Fiber Coagulated Yogurt

[0106] (1) This comparative example provides a set yogurt containing traditional dietary fiber (polydextrose), which is composed of the following raw materials: 100 mL of whole milk, 7 g of white sugar, 0.1 g of mixed bacteria (including thermophilic Streptococcus, bulgaricus, Lactococcus lactis and bifidobacterium mixed bacteria, the ratio of the four being 1:1:1:1), and 1 g of polydextrose.

[0107] (2) The processing and preparation method is the same as that in Example 1.

[0108] Comparative Example 3 Preparation method of traditional coagulated yogurt

[0109] (1) This comparative example provides a method for preparing a traditional set yogurt, which is composed of the following raw materials: 100 mL of whole milk, 7 g of white sugar, and 0.1 g of a mixed bacterial strain (including thermophilic Streptococcus, bulgaricus, Lactococcus lactis and bifidobacterium mixed bacterial strains, the ratio of the four being 10:3:1:1).

[0110] (2) The processing and preparation method is the same as that in Example 1.

[0111] Comparative Example 4 Preparation method of traditional dietary fiber coagulated yogurt

[0112] (1) This comparative example provides a set yogurt containing traditional dietary fiber (polydextrose), which is composed of the following raw materials: 100 mL of whole milk, 7 g of white sugar, 0.1 g of mixed bacteria (including thermophilic Streptococcus, bulgaricus, Lactococcus lactis and bifidobacterium mixed bacteria, the ratio of the four being 10:3:1:1), and 1 g of polydextrose.

[0113] (2) The processing and preparation method is the same as that in Example 1.

[0114] Comparative Example 5 Preparation method of traditional coagulated yogurt

[0115] (1) This comparative example provides a method for preparing a traditional set yogurt, which is composed of the following raw materials: 100 mL of whole milk, 7 g of white sugar, and 0.1 g of a mixed bacterial strain (including thermophilic Streptococcus, bulgaricus, Lactococcus lactis and bifidobacterium mixed bacterial strains, the four of which are in a ratio of 6:2:1:1).

[0116] (2) The processing and preparation method is the same as that in Example 1.

[0117] Comparative Example 6: Set-type yogurt containing traditional dietary fiber (polydextrose)

[0118] (1) This comparative example provides a set yogurt containing traditional dietary fiber (polydextrose), which is composed of the following raw materials: 100 mL of whole milk, 7 g of white sugar, 0.1 g of mixed bacteria (including thermophilic Streptococcus, bulgaricus, Lactococcus lactis and bifidobacterium mixed bacteria, the ratio of the four being 6:2:1:1), and 1 g of polydextrose.

[0119] (2) The processing and preparation method is the same as that in Example 1.

[0120] Comparative Example 7: Common corn starch

[0121] Ordinary corn starch that has not been processed by any technology or method.

[0122] Comparative Example 8 Preparation Method of Octenyl Succinate Starch Ester

[0123] This comparative example provides a method for preparing octenyl succinate starch ester, comprising the following steps: suspending comparative example 3 in deionized water to obtain a starch suspension with a concentration of 10% (w / w), adjusting the pH to 8.0-8.5, taking 3% OSA of the dry basis weight of starch, diluting it 5 times with isopropanol, and slowly dripping it into the starch suspension, maintaining the temperature at 35°C and the pH at 8.0-8.5, and reacting for a total of 3 hours. Adjust the pH to 6.5 with hydrochloric acid to terminate the esterification reaction. After freeze-drying the sample, wash it with anhydrous ethanol, and evaporate it in a fume hood for 24 hours to obtain octenyl succinate starch ester.

[0124] Comparative Example 9: Preparation method of composite resistant starch

[0125] This comparative example provides a method for preparing a composite resistant starch, comprising the following steps:

[0126] (1) Weigh 2 g of octenyl succinate starch prepared in Comparative Example 4, add deionized water to obtain a starch suspension with a concentration of 7% (w / w), stir evenly, and then add 6% (w / w) of palmitic acid diglyceride based on the dry weight of starch.

[0127] (2) Processing and preparation method: The obtained starch-palmitic acid diglyceride suspension was heated and stirred in a 90°C water bath for 2 hours, and then cooled to 25°C during stirring for 4 hours. The obtained paste was quickly frozen with liquid nitrogen, and the sample was vacuum freeze-dried and ground and sieved. The obtained powder was washed alternately with n-hexane and anhydrous ethanol to remove free palmitic acid diglyceride, and placed in a fume hood overnight to evaporate the residual liquid. Composite resistant starch was obtained.

[0128] Comparative Example 10: A method for preparing gelatinized starch

[0129] This comparative example provides a method for preparing gelatinized starch, comprising the following steps: weighing 2 g of comparative example 3, adding deionized water to obtain a starch suspension with a concentration of 7% (w / w), and the processing and preparation method is the same as that of comparative example 9.

[0130] Comparative Example 11 Preparation method of gelatinized octenyl succinate starch ester

[0131] This comparative example provides a method for preparing gelatinized octenyl succinate starch ester, comprising the following steps: weighing 2 g of octenyl succinate starch ester prepared in comparative example 4, adding deionized water to obtain a starch suspension with a concentration of 7% (w / w), and the processing and preparation method is the same as that of comparative example 9.

[0132] Example 16 Comparative Testing - Determination of Texture Characteristics

[0133] The test results of the composite resistant starch prepared by the present invention and all the embodiments and comparative examples are as follows:

[0134] All yogurt samples were tested using a texture analyzer (TA-XTplus, Stable Micro Systems, UK) equipped with a P / 36R cylindrical probe (see Table 1).

[0135] Table 1 Hardness, cohesion and adhesiveness of yogurt

[0136]

[0137] Note: The data in the table are mean ± standard deviation. The same suffix letters indicate no significant difference, and different letters indicate significant difference (p < 0.05).

[0138] Hardness characterizes the ability of yogurt to resist compression, while cohesiveness is expressed as the energy required to chew semi-solid food until it is swallowed, reflecting the interaction between molecules inside the sample and the changes in the microstructure. The experimental results show that the hardness, cohesion and cohesiveness of the yogurt with added composite resistant starch (Examples 1-3) are greater than those of the traditional coagulated yogurt and the yogurt with added polydextrose (Comparative Examples 1-2), which means that the addition of composite resistant starch enhances the cohesive strength of the internal structure of the yogurt.

[0139] Example 17 Comparative test - determination of pH value, acidity and water holding capacity

[0140] The yogurt prepared in Examples 1-3 and Comparative Examples 1-2 was placed at room temperature (20-25°C), 5 g of the sample was weighed, 20 mL of deionized water was added to prepare a mixed solution, the sample acidity was measured by titration with 0.1 M sodium hydroxide standard solution, and the sample pH value was measured with a pH meter. The water holding capacity was determined by weighing 10 g of the yogurt prepared in Examples 1-3 and Comparative Examples 1-2, centrifuging at 4°C and 4000 rpm for 15 min, and then accurately weighing the precipitate, and recording the water holding capacity of the yogurt during storage (such as Figure 1 ).

[0141] The experimental results show that the pH value of the yogurt (Examples 1-3) with the addition of composite resistant starch on the first day is higher than that of the traditional coagulated yogurt and the yogurt with the addition of polydextrose (Comparative Examples 1-2), and the acidity is lower than that of the traditional coagulated yogurt and the yogurt with the addition of polydextrose (Comparative Examples 1-2), and this effect is enhanced with the increase of the addition amount of composite resistant starch. After storage for 7 days, the pH value and acidity of the traditional coagulated yogurt (Comparative Example 1) have stabilized, but the pH value and acidity of the yogurt with the addition of composite resistant starch are still changing. The addition of composite resistant starch yogurt (Examples 1-3) significantly improves the water holding capacity of yogurt. During the storage of yogurt, the stability effect of the yogurt (Examples 1-3) with the addition of composite resistant starch is better than that of the traditional coagulated yogurt and the yogurt with the addition of polydextrose (Comparative Examples 1-2), among which Example 3 has the best water holding capacity during storage.

[0142] Example 18 Comparative Testing - Determination of Rheological Properties

[0143] The flow properties of all yogurt samples were measured by a rotational rheometer (MCR302, Anton Paar, Australia) using a flat plate (PP25, 25 mm diameter, 1 mm gap) at 4 °C and recording shear rates of 0.01–100 s -1 The storage modulus (G') and loss modulus (G") were measured in the range of 0.1-10 Hz, with a constant shear strain of 0.5%, and the linear viscoelastic region was determined by an amplitude sweep test (0.01-100%, fixed at 1 Hz) (e.g. Figure 2 and 3 ).

[0144] The experimental results show that all yogurt samples show a trend of decreasing viscosity with increasing shear rate, indicating that yogurt is a pseudoplastic fluid. During storage, the viscosity decrease (35-60%) of the yogurt with added composite resistant starch (Examples 1-3) is lower than that of the traditional coagulated yogurt (75%) and the yogurt with added polydextrose (73%) (Comparative Examples 1-2), and the decrease in modulus (15-40%) is also lower than that of the traditional coagulated yogurt (83%) and the yogurt with added polydextrose (64%) (Comparative Examples 1-2). The viscosity and modulus of Example 3 remain basically unchanged during storage, indicating that the addition of composite resistant starch can improve the storage stability of yogurt, and the more the amount added, the more obvious the effect of stabilizing yogurt.

[0145] Example 19 Comparative test - Determination of short-chain fatty acids (SCFAs) content

[0146] Weigh 3g of all yogurt samples, add 9mL of 0.5% (v / v) hydrochloric acid-ethanol solution, vortex all yogurt samples for 1min, centrifuge at 4℃14000rpm for 10min, and take the supernatant for determination. Filter with a 0.45μm organic filter membrane before injection, and accurately draw 1μL of sample for injection. The gas chromatograph used is GC-2010 Pro (Shimadzu, Japan), flame ionization detector (FID) and quartz capillary column ZB-FFAP (J&W Scientific, USA). During the test, the injector temperature was set to 230℃ and the detector temperature was set to 230℃. The column temperature was initially set to 80℃ and increased to 192℃ at a rate of 8℃ / min. Nitrogen was used as the carrier gas with a flow rate of 1mL / min (such as Figure 4 ).

[0147] The experimental results show that in the later storage period (14-21 days), the propionic acid content of the yogurts with added composite resistant starch (Examples 1-3) is greater than that of the traditional set yogurt and the yogurt with added polydextrose (Comparative Example 1), among which the propionic acid content of Example 3 increases the most in the later storage period, reaching 2.94 mMol / L ( Figure 4 B). Similarly, the butyric acid content of the yogurts with added composite resistant starch (Examples 1-3) is greater than the butyric acid content of the traditional coagulated yogurt (Comparative Example 1). Figure 4 C). Although the total short-chain fatty acid content of the yogurt with added composite resistant starch was lower than that of the traditional set yogurt and the yogurt with added polydextrose (Comparative Examples 1-2) on the first day, as the storage time increased, the total short-chain fatty acid content of Comparative Examples 1-2 tended to be stable on the 14th day, but the total short-chain fatty acid content of Examples 1-3 gradually increased ( Figure 4 D).

[0148] Example 20 Comparative Testing - Sensory Evaluation Measurement

[0149] Ask 10 consumers who have undergone sensory training to conduct sensory tests on all yogurt samples and rate them in terms of smoothness, thickness, clumping, sourness, aftertaste, stickiness, creaminess and overall acceptance, with a maximum score of 10. The average value is taken (e.g. Figure 5 ).

[0150] The experimental results show that the yogurt with added composite resistant starch (Examples 1-3) is superior to the traditional coagulated yogurt and the yogurt with added polydextrose (Comparative Examples 1-2) in terms of smoothness, thickness and viscosity, and the creaminess of the yogurt with added composite resistant starch (Examples 1-3) is superior to the traditional coagulated yogurt (Comparative Example 1), indicating that the addition of composite resistant starch can improve the taste quality of yogurt, and thus is more easily accepted by consumers. Among them, the yogurt of Example 4 has a lower hardness and a lighter sour taste, which is suitable for the middle-aged and elderly groups, and the yogurt of Example 2 has a moderate hardness and sour taste, which is suitable for the young consumer group.

[0151] Example 21 Comparative Detection - X-ray Diffraction Determination

[0152] The X-ray diffractometer (D8 Advance) of Bruker, Germany, was used to determine the content of native starch, octenyl succinate starch ester and composite resistant starch (such as Figure 6 A). The experimental results show that comparative examples 7 and 8 have diffraction peaks at 15.1°, 17.1°, 18.0° and 23.2° (2θ), respectively, and these peaks show a typical A-type crystal structure. The composite resistant starch obtained by compounding octenyl succinate starch ester with lipids has obvious diffraction peaks at 12.9° and 19.8° (2θ) (Comparative Example 9), which is a typical V-type crystal structure.

[0153] Weigh 20 mg of starch sample and add deionized water to make a 1% suspension. Heat the centrifuge tube at 60°C and 85°C for 30 min. After the sample is cooled, centrifuge at 4°C and 13000 rpm for 10 min. Weigh the precipitate and measure the swelling capacity of gelatinized starch, gelatinized octenyl succinate starch ester and composite resistant starch at 60°C and 85°C (e.g. Figure 6 B). The experimental results show that the swelling power of the composite resistant starch (Comparative Example 9) at 60°C and 85°C is significantly higher than that of the gelatinized starch (Comparative Example 10) and the gelatinized OSA starch (Comparative Example 11).

[0154] Example 22 Comparative Detection - Differential Scanning Calorimetry

[0155] The native starch, octenyl succinate starch ester and composite resistant starch (as shown in Table 2) were analyzed using a differential scanning calorimeter (200F3) from Netzsch, Germany. Comparative Examples 7 and 8 both showed melting peaks between 60-75°C, while Comparative Example 9 showed a melting peak in a higher temperature range (90-110°C), indicating that the composite resistant starch has higher thermal stability.

[0156] Table 2 Thermodynamic properties of different types of starch

[0157]

[0158] Through the measurement of Examples 4 to 12, it was found that the prepared set yogurt containing composite resistant starch was superior to the traditional set yogurt and the yogurt with added traditional dietary fiber (polydextrose) in terms of taste quality and storage stability.

[0159] Based on the above experimental data and result analysis, the present invention provides a method for preparing a coagulated yogurt containing composite resistant starch. Compared with traditional coagulated yogurt and commercial yogurt with traditional dietary fiber (polydextrose), the addition of composite resistant starch improves the water retention and hardness of yogurt, promotes the storage stability of yogurt and gives yogurt ideal properties such as smoothness, thickness and creaminess. Among them, the yogurt with 4% (w / w) composite resistant starch added has a lower hardness and is suitable for the middle-aged and elderly groups, and the yogurt with 2% (w / w) composite resistant starch added has a higher hardness and is suitable for the youth consumer group, thereby realizing the dynamic controllability of yogurt products. As a new type of dietary fiber, composite resistant starch can promote bifidobacteria in yogurt to produce short-chain fatty acids, especially butyric acid and propionic acid. The preparation process of the present invention is simple and easy to operate, and it has potential significance for improving the nutritional health of the human intestinal tract.

[0160] 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 is described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

[0161] All structural changes made based on the concept of the present invention without creative work fall within the protection scope of the present invention.

Claims

1. A set yogurt containing composite resistant starch, characterized in that: The yogurt is made from the following raw materials: 80-99% (w / w) whole milk, 1-10% (w / w) white sugar, 0.5-10% (w / w) composite resistant starch, and 0.01-0.5% (w / w) starter, wherein the composite resistant starch is mainly obtained by chemically modifying gelatinized corn starch and then reacting with lipids, and the main component is composed of RS4 and RS5 reacting with each other.

2. The set yogurt of composite resistant starch according to claim 1, characterized in that: The yogurt is prepared from the following raw materials: 85-95% (w / w) of whole milk, 5-9% (w / w) of white sugar, 1-8% (w / w) of composite resistant starch, and 0.05-0.2% (w / w) of starter.

3. The set yogurt of composite resistant starch according to claim 1, characterized in that: The composite resistant starch is prepared by a method comprising the following steps: (1) preparing a starch suspension by mixing corn starch with water, heating, freeze-drying, and obtaining gelatinized starch; (2) mixing gelatinized starch with water to prepare a starch suspension, adjusting the pH, adding octenyl succinic anhydride, and freeze-drying to obtain RS4; (3) RS4 is suspended in water, diglyceride is added, the mixture is heated and stirred, and freeze-dried to obtain composite resistant starch (RS4+RS5).

4. The set yogurt of composite resistant starch according to claim 2, characterized in that: The yogurt is prepared from the following raw materials: 88-93% (w / w) of whole milk, 6-8% (w / w) of white sugar, 2-5% (w / w) of composite resistant starch and 0.1% (w / w) of starter.

5. The set yogurt containing composite resistant starch according to claim 4, characterized in that: The yogurt is prepared from the following raw materials: 88.9-91.9% (w / w) of whole milk, 7% (w / w) of white sugar, 4% (w / w) of composite resistant starch and 0.1% (w / w) of starter.

6. The set yogurt containing composite resistant starch according to claim 4, characterized in that: The yogurt is prepared from the following raw materials: 88.9-91.9% (w / w) of whole milk, 7% (w / w) of white sugar, 2% (w / w) of composite resistant starch and 0.1% (w / w) of starter.

7. A method for preparing the set yogurt containing composite resistant starch according to claims 1-6: (1) Preheat milk, add sugar and composite resistant starch, and mix well; sterilize at 80-85°C; (2) After the temperature has cooled, add the mixed bacteria as a fermentation agent, ferment, and store at low temperature.

8. The method for preparing a set yogurt containing composite resistant starch according to claim 7, characterized in that: (1) After preheating the whole milk, add white sugar and composite resistant starch, and mix the three evenly; sterilize at 80-85°C for 20-30 minutes; (2) After the temperature has cooled, add the mixed bacteria as a fermentation agent, the inoculation amount of the mixed bacteria is 0.1-0.5% (w / w), and place the inoculated milk at a temperature of 40-44° C. for fermentation; the fermented yogurt is stored at 4° C.

9. The method of claim 8, characterized in that Step (1) Heat whole milk to 60° C., gradually add white sugar and composite resistant starch under stirring at 600 rpm, and stir for 30 minutes.

10. The method according to claim 8, characterized in that Step (1) Heat the preheated and mixed milk at 85° C. for 20 minutes.

11. The method according to claim 7, characterized in that: The fermentation agent of step (2) comprises thermophilic streptococcus, bulgaricus lactobacillus, lactobacillus lactis and bifidobacterium, and the mass ratio of the four is 10:3:1:1 to 1:1:1:

1.

12. The method according to claim 11, characterized in that: The fermentation agent of step (2) has a viable bacterial count of ≥ 1×10 7 CFU / g.

13. The method according to claim 7, characterized in that: Step (2) When the milk is cooled to 43°C, 0.1% (w / w) starter culture is added, stirred at 600 rpm for 10 minutes, and then fermented for 7 hours.

14. The method according to claim 6, characterized in that The fermented yogurt in step (2) is stored at 4° C. for 24 hours.

15. The method according to claim 7, characterized in that The added composite resistant starch is mainly composed of RS4 and RS5, which has the dual functional probiotic properties of RS4 and RS5, and has a V-type crystal structure with a crystallinity range of 19.1-21:1%. The main content of the added composite resistant starch is type I complex, and T p In the range of 90-110°C, at 85°C, the swelling power of composite resistant starch (20-30%) was higher than that of gelatinized starch (9.0%).

16. The composite resistant starch according to claims 1 to 6, characterized in that:RS4 has an A-type crystal structure, which is different from natural starch at 1572 cm -1 and 1726cm -1 RS5 has a V-type crystal structure, and compared with natural starch, it has a new absorption peak at 1710 cm -1 and 2857cm -1 A new absorption peak appeared.

17. Use of the coagulated yogurt containing the composite resistant starch according to claims 1-6 in the yogurt consumption groups of the middle-aged, elderly and adolescents.

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