Frozen dough added with stachyose and preparation method thereof

Abstract

The invention discloses frozen dough added with stachyose and a preparation method of the frozen dough, and belongs to the technical field of food processing. The instant noodles are prepared from the following raw materials in parts by weight: 80-100 parts of medium gluten wheat flour, 0.8-1.2 parts of dried yeast, 40-60 parts of water and 0.5-2.0 parts of stachyose. The preparation method comprises the following steps: adding water into the dried yeast for activation, and mixing and stirring the activated dried yeast with the medium-gluten wheat flour; dissolving stachyose in water to obtain a solution, adding the solution into the mixture, and stirring until the dough is formed; standing and fermenting the dough, partitioning, kneading and shaping, packaging with a preservative film, and freezing and storing, so as to obtain the frozen dough added with stachyose. The stachyose is added into the dough, so that the quality deterioration of the dough caused by freezing treatment can be effectively improved. In addition, the stachyose is added, so that the blood sugar rising rate after flour products such as steamed buns are eaten can be reduced, and the pursuit of people for health is met.

Description

Technical Field

[0001] The present invention belongs to the technical field of food processing, and particularly relates to a frozen dough added with stachyose and a preparation method thereof. Background Art

[0002] The frozen dough technology combines dough products with freezing technology to produce semi-finished or finished products. In recent years, frozen dough has attracted wide attention due to its advantages such as convenient storage and transportation, low production cost, and high safety, and has gradually become a key technical means for the industrialized and standardized production of flour products such as steamed buns and dumplings. However, the free water in the frozen dough is easily formed into ice crystals during the freezing process, and the ice crystals will damage the gluten network structure of the dough. Gluten proteins wrap around starch granules, and when the dough is quickly thawed after freezing, a tightly structured network will be formed. In the unfrozen dough, the gluten proteins maintain a highly interconnected three-dimensional network structure with dense and uniform pores. Frozen storage will cause damage to the gluten network, resulting in a rough gluten structure, exposure of starch granules, and the appearance of larger pores. In addition, frozen dough will change the physical and chemical properties of wheat starch, affecting crystallinity and other factors. Therefore, how to improve the stability of frozen dough and delay its quality deterioration is an urgent technical problem to be solved.

[0003] Polysaccharides, hydrocolloids, enzyme preparations, antifreeze proteins, emulsifiers, etc. are commonly used as quality improvers for frozen dough to inhibit water loss, slow down starch retrogradation, and maintain yeast activity. Among them, the production costs of antifreeze proteins and enzyme preparations are high, and their application ranges are limited; the intake of emulsifiers has the risk of inducing autoimmune diseases in the body. Food polysaccharides and hydrocolloid additives have become a research hotspot in this field due to their advantages of economy and good safety effects.

[0004] Stachyose is a naturally occurring functional oligosaccharide composed of 1 molecule of fructose, 1 molecule of glucose, and 2 molecules of galactose, and has good thermal stability and solubility. As a natural prebiotic, stachyose can not only regulate the balance of the intestinal microbial community and promote intestinal health, but also is not hydrolyzed by digestive enzymes and its metabolism does not depend on insulin, and can assist in reducing blood pressure and blood lipid levels, and can meet the needs of special populations such as diabetes, obesity, and hyperlipidemia. Although there have been some research reports on polysaccharides improving the quality of dough, there are no reports on the research of stachyose in frozen flour products, and stachyose has multiple beneficial effects on the human body compared with other polysaccharides, and is a highly potential functional polysaccharide. Summary of the Invention

[0005] Technical problem to be solved: In view of the above technical problems, the present invention provides a frozen dough added with stachyose and its preparation method, which overcomes the defects that the quality of the frozen dough deteriorates after freeze-thaw treatment and the taste of the prepared food becomes worse in the prior art. It can improve the elasticity of the frozen dough, improve the viscoelasticity and gluten network structure, and alleviate the quality deterioration of the frozen dough.

[0006] Technical solution: A frozen dough added with stachyose, the raw materials of which are calculated by weight, include 80-100 parts of medium-gluten wheat flour, 0.8-1.2 parts of dry yeast, 40-60 parts of water, and 0.5-2.0 parts of stachyose.

[0007] Preferably, the protein content in the medium-gluten wheat flour is 9-12%.

[0008] Preferably, the purity of the stachyose is 60-70%.

[0009] A preparation method of a frozen dough added with stachyose includes the following steps:

[0010] Step 1: Activate the dry yeast by adding water, and mix and stir it with the medium-gluten wheat flour after activation.

[0011] Step 2: Dissolve the stachyose in water to obtain a solution, and then add it to the mixture in Step 1 and stir until the dough is formed.

[0012] Step 3: Let the dough stand for proofing, divide it into pieces, knead and shape it, wrap it with plastic wrap and store it frozen to obtain the frozen dough added with stachyose.

[0013] Preferably, in Step 1, the water temperature for activation is 35-45°C and the activation time is 0.5 h.

[0014] Preferably, in Step 2, the water temperature for dissolving the stachyose is 20-30°C.

[0015] Preferably, in Step 2, the stirring process is: stir at a low speed of 30-100 rpm for 3-5 min, and stir at a high speed of 150-300 rpm for 8-10 min.

[0016] Preferably, in Step 3, the standing proofing time is 10-20 min and the temperature is 25°C.

[0017] Preferably, in Step 3, the specification of the dough divided into pieces is 50±0.5 g / piece.

[0018] Preferably, in Step 3, the freezing temperature is -20°C and the time is 7 days.

[0019] Beneficial effects: By adding stachyose to the dough, the present invention can effectively improve the quality deterioration of the dough caused by freezing treatment. Specifically speaking, adding stachyose can improve the viscoelasticity of the frozen dough and the stability of the gluten network structure, making the frozen dough have good processing quality. In addition, stachyose can beneficially combine with the starch-gluten protein structure, inhibit the contact and hydrolysis of starch and amylase, reduce the digestibility of starch, and thus reduce the rate of blood sugar rise. The present invention not only promotes the development of the frozen noodle products industry, but also meets the pursuit of people for health, and has broad market prospects. Description of the Drawings

[0020] Figure 1 Results of the determination of the rheological properties of the frozen doughs of Examples 1 to 4 and Comparative Example 1;

[0021] Figure 2 Results of the scanning electron microscope observation of the frozen doughs of Examples 1 to 4 and Comparative Example 1;

[0022] Figure 3 Fitting curves of the starch digestion rates of the steamed buns made from the frozen doughs of Examples 1 to 4 and Comparative Example 1. Detailed Embodiments

[0023] The present invention will be further described below in conjunction with the drawings and specific embodiments. In the following embodiments, unless otherwise specified, the raw materials or processing techniques used indicate that the commonly available raw material products or conventional processing techniques in the art are adopted.

[0024] In the following embodiments, the protein content in the medium-gluten wheat flour used is 9-12%; the purity of the stachyose used is 60-70%.

[0025] Example 1

[0026] 1) Prepare 100 parts of medium-gluten wheat flour, 55 parts of water, 1 part of dry yeast, and 0.5 part of stachyose;

[0027] 2) Put the dry yeast into warm water (15 parts) at 37°C and activate it for 0.5 h, then put the flour and the activated yeast solution into a dough mixer and stir at low speed;

[0028] 3) Uniformly disperse the stachyose in water (40 parts) at 25°C and stir well to dissolve it;

[0029] 4) Slowly and uniformly pour the dissolved stachyose solution into the dough mixer stirring at low speed;

[0030] 5) After the dough mixer stirs at low speed (60 rpm) for 3 min and at high speed (180 rpm) for 8 min, cover it with plastic wrap and let it stand and proof at 25°C for 15 min;

[0031] 6) Divide the dough into small dough pieces with a specification of 50 ± 0.5 g per piece, manually knead and shape them, wrap them with plastic wrap, and store them in a -20°C refrigerator for 7 days.

[0032] Example 2

[0033] 1) Prepare 100 parts of medium-gluten wheat flour, 55 parts of water, 1 part of dry yeast, and 1 part of stachyose.

[0034] 2) Put the dry yeast into warm water at 37°C (15 parts) and activate it for 0.5 h. Then put the flour and the activated yeast liquid into a dough mixer and stir at a low speed.

[0035] 3) Evenly disperse the stachyose in water at 25°C (40 parts), and stir well to dissolve it.

[0036] 4) Slowly and evenly pour the dissolved stachyose solution into the dough mixer that is stirring at a low speed.

[0037] 5) After the dough mixer stirs at a low speed (60 rpm) for 3 min and at a high speed (180 rpm) for 8 min, cover it with plastic wrap and let it stand and proof at 25°C for 15 min.

[0038] 6) Divide the dough into small dough pieces with a specification of 50 ± 0.5 g per piece, manually knead and shape them, wrap them with plastic wrap, and store them in a -20°C refrigerator for 7 days.

[0039] Example 3

[0040] 1) Prepare 100 parts of medium-gluten wheat flour, 55 parts of water, 1 part of dry yeast, and 1.5 parts of stachyose.

[0041] 2) Put the dry yeast into warm water at 37°C (15 parts) and activate it for 0.5 h. Then put the flour and the activated yeast liquid into a dough mixer and stir at a low speed.

[0042] 3) Evenly disperse the stachyose in water at 25°C (40 parts), and stir well to dissolve it.

[0043] 4) Slowly and evenly pour the dissolved stachyose solution into the dough mixer that is stirring at a low speed.

[0044] 5) After the dough mixer stirs at a low speed (60 rpm) for 3 min and at a high speed (180 rpm) for 8 min, cover it with plastic wrap and let it stand and proof at 25°C for 15 min.

[0045] 6) Divide the dough into small dough pieces with a specification of 50 ± 0.5 g per piece, manually knead and shape them, wrap them with plastic wrap, and store them in a -20°C refrigerator for 7 days.

[0046] Example 4

[0047] 1) Prepare 100 parts of medium-gluten wheat flour, 55 parts of water, 1 part of dry yeast, and 2 parts of stachyose;

[0048] 2) Put the dry yeast into warm water at 37°C (15 parts) and activate it for 0.5 h. Then put the flour and the activated yeast liquid into a dough mixer and stir at a low speed;

[0049] 3) Evenly disperse the stachyose in water at 25°C (40 parts) and stir well to dissolve it;

[0050] 4) Slowly and evenly pour the dissolved stachyose solution into the dough mixer stirring at a low speed;

[0051] 5) After the dough mixer stirs at a low speed (60 rpm) for 3 min and at a high speed (180 rpm) for 8 min, cover it with plastic wrap and let it stand and proof at 25°C for 15 min;

[0052] 6) Divide the dough into small doughs with a specification of 50 ± 0.5 g per piece, manually knead and shape them, wrap them with plastic wrap, and store them in a refrigerator at -20°C for 7 days.

[0053] Comparative Example 1

[0054] 1) Prepare 100 parts of medium-gluten wheat flour, 55 parts of water, and 1 part of dry yeast;

[0055] 2) Put the dry yeast into warm water at 37°C (15 parts) and activate it for 0.5 h. Then put the flour and the activated yeast liquid into a dough mixer and stir at a low speed;

[0056] 3) Evenly disperse the stachyose in water at 25°C (40 parts) and stir well to dissolve it;

[0057] 4) Slowly and evenly pour the dissolved stachyose solution into the dough mixer stirring at a low speed;

[0058] 5) After the dough mixer stirs at a low speed (60 rpm) for 3 min and at a high speed (180 rpm) for 8 min, cover it with plastic wrap and let it stand and proof at 25°C for 15 min;

[0059] 6) Divide the dough into small doughs with a specification of 50 ± 0.5 g per piece, manually knead and shape them, wrap them with plastic wrap, and store them in a refrigerator at -20°C for 7 days.

[0060] Dough quality test:

[0061] 1. Determination of the rheological properties of frozen dough

[0062] The frozen dough was thawed at 4 °C for 4 h and then at room temperature for 0.5 h. A small piece was taken from the center part and placed on the test bench. A 40-mm parallel plate was installed on the rheometer. An amplitude sweep test was carried out at a frequency of 1 Hz in the range of 0.1% to 100% to determine the linear viscoelastic region of the dough, and it was found that this region was 0.1%. Then a frequency sweep test was carried out at 25 °C with a strain amplitude of 0.1% set in the range of 0.1 to 100 Hz, using a 2-mm gap. The storage modulus (G′), loss modulus (G″), and tanδ (G′ / G″) within its linear viscoelastic region were determined by dynamic sweep tests. Each group of measurements was repeated three times, and the results are shown in Figure 1 。

[0063] The rheological properties can reflect the viscoelastic properties of the dough. From Figure 1 it can be seen that the storage modulus (G′) and viscosity modulus (G″) of the frozen dough gradually increase with the increase of frequency, and G′ is always greater than G″, indicating that the dough is mainly dominated by the storage modulus. Compared with Comparative Example 1, the G′ and G″ of the frozen dough in Examples 1 to 4 all increased to varying degrees, indicating that the addition of stachyose can improve the viscoelasticity of the frozen dough. From Figure 1 it can be known that the tanδ value of the dough is always <1, indicating that all doughs have typical elastic and solid-like properties.

[0064] 2. Observation of the microstructure of frozen dough

[0065] After 7 days of freezing, the dough was transferred from the refrigerator to a vacuum freeze dryer, dried at -148 °C for 24 h, and then crushed and passed through a 100-mesh sieve. The dough powder was attached to a conductive adhesive and sputter-coated with gold. Then it was operated at an acceleration voltage of 5 kV with a magnification of 2000 times.

[0066] The elliptical objects in the figure are starch granules, which are tightly wrapped in the gluten network structure or exposed above the gluten network. The black holes appearing in the figure may be formed by the mixing of gas in the gluten network during the hydration process of the dough, or may be the spaces left by the sublimation of ice crystals during the freeze-drying process. From Figure 2 it can be seen that after freezing treatment, the gluten network structure of the dough was severely damaged, with large and uneven voids, and a large number of starch granules were exposed outside the gluten matrix, and the gluten protein structure was loose and irregular. Compared with Comparative Example 1 (stachyose addition amount of 0%), the dough holes in Examples 1 to 4 (stachyose addition amounts of 0.5%, 1%, 1.5%, and 2% respectively) became smaller, and the continuity of the dough gluten network was somewhat improved. Especially in Examples 2 and 3, it can be clearly seen that the number of exposed starch granules decreased, the pores were uniform, and the gluten network structure was more continuous, which can improve the stability of the dough.

[0067] 3. Determination of the texture properties of frozen dough

[0068] After 7 days of freezing, the frozen dough was thawed at 4 °C for 4 h, and a part of the dough was taken to make its average thickness 20 mm. Using a TA-XT texture analyzer, in the TPA mode and with a P / 0.5 spherical probe, the texture properties of the dough were measured, including hardness, elasticity and cohesiveness. The parameter settings were as follows: the speeds before measurement, during measurement and after measurement were 2.0 mm / s, 1.0 mm / s and 2.0 mm / s respectively. The trigger force was 5.0 g, the time interval was 5 s, the contact force was 5 g, and the strain was set at 40%. Each group of measurements was repeated three times. The results are shown in Table 1.

[0069] Table 1 Measurement results of the texture properties and static in vitro digestion properties of the frozen dough of Examples 1-4 and Comparative Example 1

[0070]

[0071]

[0072] Note: The values are mean ± standard deviation. The means with different letters in the columns are significantly different (p ≤ 0.05).

[0073] Hardness is one of the most commonly used parameters to evaluate the degree of spoilage of steamed buns, which affects the dough processing operation and the taste of the finished product. Dough that is too hard is not easy to plastically process and does not expand completely; dough that is too soft is prone to collapse, affecting the shape and structure of the product. As shown in Table 1, after adding stachyose, compared with the dough of Comparative Example 1 (0%), the hardness of the doughs of Examples 1-4 (0.5%, 1%, 1.5%, 2%) decreased, and the deterioration of the dough was improved, and the effects of Examples 3 and 4 (1.5%, 2%) were more obvious.

[0074] Elasticity is usually used to describe the ability of an object to recover from a deformed state. Dough with good elasticity can withstand operations such as stretching during processing without breaking, and can retain the gas generated by fermentation, making its products such as steamed buns and breads large in volume, with uniform pores and softer texture. As shown in Table 1, after adding stachyose, compared with the dough of Comparative Example 1 (0%), the elasticity of the doughs of Examples 1-4 (0.5%, 1%, 1.5%, 2%) was significantly improved, indicating that adding stachyose can improve the quality deterioration of the dough during the freezing process.

[0075] Cohesiveness can reflect the strength of the binding between molecules inside the dough and the dough's ability to resist breakage. A dough with good cohesiveness is not easily damaged during processing, can maintain a complete shape, and helps to maintain the internal structure of the dough, resulting in a delicate and resilient texture of the finished product. As shown in Table 1, after adding stachyose, compared with the dough of Comparative Example 1 (0%), the cohesiveness of the doughs of Examples 1-4 (0.5%, 1%, 1.5%, 2%) increased significantly, and the effects of Examples 2 and 3 (1%, 1.5%) were more obvious, indicating that adding stachyose enhances the binding strength of the starch-gluten network inside the dough and improves the stability of the dough.

[0076] 4. Static in vitro digestion determination of frozen dough steamed buns

[0077] After freezing for 7 days, thaw the frozen dough at 4°C for 4 h, ferment at 37°C for 60 min, and the relative humidity is 75±5%. Steam the fermented dough in boiling water for 25 min, and then cool it completely at room temperature for 1 h. Transfer the steamed buns to a vacuum freeze dryer, dry them at -148°C for 24 h, then crush them and pass through a 100-mesh sieve. Dissolve 200 mg of the sample (powder) in 10 ml of sodium acetate buffer (0.1 M, pH 5.2), and add 10 mL of a newly prepared enzyme solution containing 280 U / mL α-amylase and 15 U / mL glucoamylase to this mixture.

[0078] Incubate the resulting solution in a thermostatic shaker at 37°C and 170 rpm to simulate in vitro digestion. Collect hydrolysis solution samples at 0, 5, 10, 15, 20,

[0079] 30, 50, 70, 90, 120, and 180 minutes to monitor the digestion process. To stop the enzyme activity at each time point, mix 0.2 mL of the hydrolyzate with 0.8 mL of ethanol solution. Then measure the glucose content in each sample using a glucose assay kit based on the glucose oxidase-peroxidase (GOD-POD) method. The calculation formula is:

[0080]

[0081] Where: G is the glucose content in the test solution (mmol / L); A0 is the absorbance of the blank solution at 505 nm; A1 is the absorbance of the test solution at 505 nm; A2 is the absorbance of the standard solution at 505 nm; C0 is the standard concentration, 5.55 mmol / L.

[0082] Calculate the digestion amount of starch based on the glucose content, plot the digestion rate curve, and use the following conversion equation: C = G × 0.9. To analyze the digestion characteristics of the samples, the data was fitted according to the first-order hydrolysis kinetic function. The conversion equation of the first-order hydrolysis kinetic function is: C = C∞ × (1 - exp(-k1t)). Calculate the values of RDS, SDS, and RS. The specific formulas are as follows:

[0083] RDS = G 20 × 0.9 × 100%

[0084] SDS = (G 120 - G 20 ) × 0.9 × 100%

[0085] RS% = 100 - RDS% - SDS%

[0086] Where: G 20 : The content of glucose (mg) in the supernatant after 20 min of enzymatic hydrolysis;

[0087] G 120 : The content of glucose (mg) in the supernatant after 120 min of enzymatic hydrolysis;

[0088] RDS: The content of rapidly digestible starch in the sample (%

[0089] SDS: The content of slowly digestible starch in the sample (%

[0090] RS: The content of resistant starch in the sample (%

[0091] Determine the static in vitro digestion characteristics of frozen dough steamed buns by the above test method, and the results are shown in Table 1 and Figure 3 .

[0092] The starch in the steamed buns can be rapidly hydrolyzed under the action of amylase, and a large amount is converted into glucose and absorbed in a short time, which causes a rapid increase in blood sugar and is not conducive to human health. As Figure 3 can be seen, after adding stachyose, compared with Comparative Example 1 (0%), the digestion rate of starch in Examples 1 - 4 (0.5%, 1%, 1.5%, 2%) is reduced. As can be seen from Table 1, after adding stachyose, the content of rapidly digestible starch in Examples 1 - 4 (0.5%, 1%, 1.5%, 2%) is lower than that of Comparative Example 1 (0%), and the content of resistant starch is significantly higher than that of Comparative Example 1 (0%), with Example 2 showing the most obvious effect. This may be attributed to the fact that stachyose can interact with the helical structure of amylose to form a complex, bind to the hydrophobic sites of gluten proteins to form a strong gluten network, thereby strengthening the cross-linking of gluten and forming an inclusion complex, making it difficult for starch to come into contact with amylase and be hydrolyzed.

[0093] The above are only the preferred embodiments of the present invention and do not impose any formal restrictions on the present invention. Any equivalent transformation or modification made according to the essence of the present invention should be covered within the protection scope of the present invention.

Claims

1. A frozen dough with added stachyose, characterized in that: The raw materials include 80-100 parts of medium-gluten wheat flour, 0.8-1.2 parts of dry yeast, 40-60 parts of water and 0.5-2.0 parts of stachyose by weight.

2. The frozen dough with added stachyose according to claim 1, characterized in that: The protein content of the medium-gluten wheat flour is 9-12%.

3. The frozen dough with added stachyose according to claim 1, characterized in that: The purity of the stachyose is 60-70%.

4. The method for preparing frozen dough with stachyose added according to claim 1, characterized in that: The steps include: Step 1: Activate the dry yeast by adding water, and then mix it with medium-gluten wheat flour; Step 2, dissolving stachyose in water to obtain a solution, and then adding the solution to the mixture in step 1, and stirring until a dough is formed; Step 3: leaving the dough to rise, dividing it into blocks, kneading and shaping it, wrapping it with plastic wrap and freezing it for storage to obtain the frozen dough with stachyose added thereto.

5. The method for preparing frozen dough with added stachyose according to claim 4, characterized in that: In the step 1, the activation water temperature is 35-45° C., and the activation time is 0.5 h.

6. The method for preparing frozen dough with stachyose added according to claim 4, characterized in that: In the step 2, the water temperature for dissolving stachyose is 20-30°C.

7. The method for preparing frozen dough with added stachyose according to claim 4, characterized in that: In the step 2, the stirring process is: stirring at a low speed of 30-100 rpm for 3-5 min, and stirring at a high speed of 150-300 rpm for 8-10 min.

8. The method for preparing frozen dough with stachyose added according to claim 4, characterized in that: In the step 3, the fermentation time is 10 to 20 minutes at a temperature of 25°C.

9. The method for preparing frozen dough with stachyose added according to claim 4, characterized in that: In the step 3, the specification of the dough pieces is 50±0.5 g / piece.

10. The method for preparing frozen dough with added stachyose according to claim 4, characterized in that: In the step 3, the freezing temperature is -20°C and the time is 7 days.

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