Emulsion for inhibiting starch retrogradation and preparation method and application thereof

Abstract

The invention belongs to the technical field of food additives, and particularly provides an emulsion for inhibiting starch retrogradation as well as a preparation method and application thereof. Wherein the emulsion for inhibiting starch retrogradation is a composite emulsion prepared from soybean seed coat polysaccharide and sodium stearoyl lactylate. A composite system prepared from the soybean seed coat polysaccharide emulsion and sodium stearoyl lactylate has caking resistance; freezing resistance is achieved; the starch retrogradation inhibitor has the effects of inhibiting starch retrogradation and the like, effectively inhibits the retrogradation problem of the prefabricated starch product, can prolong the shelf life of flour food, and solves the problem of wrapper retrogradation of the prefabricated starch food in the transportation and storage processes.

Description

Technical Field

[0001] The invention belongs to the technical field of modified starch, and particularly relates to an emulsion for inhibiting starch retrogradation, and a preparation method and application thereof. Background Art

[0002] In recent years, changes in lifestyle have had a significant impact on the popularity of fast food and the large-scale production methods. With the rapid development of the fast food industry, the sales volume of pre-prepared foods has shown a clear upward trend. These standardized foods can be eaten with simple operations. Steamed products such as steamed dumplings, steamed buns, and crystal sticky bean buns are traditional Chinese delicacies and are widely loved by everyone. However, during the circulation and storage process, the dough skins of these steamed products will become hard, lose elasticity, and crack, which affects the taste of the steamed products. These undesirable phenomena occur because the dough skin has regenerated. Therefore, delaying the regeneration of the dough skin is an urgent problem to be solved.

[0003] At present, many methods have been discovered to delay starch aging, including chemical modification (oxidation, cross-linking and esterification, etc.), physical modification (adding food hydrocolloids, polyols and fatty acids, etc.) and enzyme treatment.

[0004] While chemical modification delays starch aging, there is a risk of chemical reagent residues, which affects the safety of starch foods.

[0005] Enzyme treatment can easily produce various hydrolysis products, which affect food quality.

[0006] Although physical modification is an economical, safe and effective method, the addition of hydrophilic colloids alone will result in large dosage and high cost. The addition of a single fatty acid will reduce starch viscosity and affect the viscoelasticity of starchy foods. Summary of the invention

[0007] Based on this, the present invention proposes an emulsion for inhibiting starch retrogradation, as well as a preparation method and application, which can effectively inhibit the retrogradation of wheat starch while ensuring food safety and product quality.

[0008] According to one aspect of the present invention, an emulsion capable of inhibiting starch retrogradation is provided, wherein the emulsion comprises a composite emulsion prepared from soybean seed coat polysaccharide and sodium stearoyl lactylate.

[0009] According to an embodiment of the present invention, the mass percentage of the soybean seed coat polysaccharide and the sodium stearoyl lactylate added is 0:1-1:0.

[0010] According to an embodiment of the present invention, 1-2% by mass of soybean oil is added to the composite emulsion.

[0011] According to another aspect of the present invention, there is provided a method for preparing an emulsion for inhibiting starch retrogradation, comprising the following steps:

[0012] Step 1, heating and melting soybean seed coat polysaccharide;

[0013] Step 2, adding soybean oil to the melted soybean seed coat polysaccharide, dispersing and homogenizing, and obtaining a soybean seed coat polysaccharide emulsion;

[0014] Step 3, storing the soybean seed coat polysaccharide emulsion for a period of time;

[0015] Step 4: Add sodium stearoyl lactylate to the soybean seed coat polysaccharide emulsion and stir at a certain temperature until it is evenly dispersed to form an emulsion.

[0016] According to an embodiment of the present invention, in step 1, the addition amount of the soybean testa polysaccharide is 0-1wt%; the heating temperature of the soybean testa polysaccharide is 65-70°C; the heating method of the soybean testa polysaccharide is water bath heating; and the heating time of the soybean testa polysaccharide is 2-3h.

[0017] According to an embodiment of the present invention, in step 2, the soybean oil is added in an amount of 1-2%, and the high-speed shearing is performed at 12000 rpm for 2 minutes.

[0018] According to an embodiment of the present invention, in step 3, the resting time of the soybean seed coat polysaccharide emulsion is 10-14 hours, and the resting temperature of the soybean seed coat polysaccharide is 4°C.

[0019] According to an embodiment of the present invention, the addition amount of sodium stearoyl lactylate in step 4 is 0-1 wt %; and the stirring temperature is 60-65°C.

[0020] According to another aspect of the present invention, there is provided an application of an emulsion for inhibiting starch retrogradation in the food field. In the process of making pasta, the emulsion is added to dough.

[0021] According to an embodiment of the present invention, the mass ratio of the emulsion to the dough is 1:45-1:50.

[0022] It can be seen from the above technical scheme that the emulsion for inhibiting starch retrogradation provided by the present invention, as well as the preparation method and application thereof, have the following beneficial effects:

[0023] The present invention adopts a method of combining soybean seed coat polysaccharide with sodium stearoyl lactylate. Sodium stearoyl lactylate is an ionic emulsifier, and experiments have shown that its emulsification effect is good in this field. Water-soluble soybean polysaccharide is a by-product of soybean processing. It is an acidic polysaccharide extracted from soybean seed coat, soybean dregs, etc. Its structure is similar to pectin. It is composed of a galacturonic acid main chain and a neutral side chain. The neutral side chain includes homogalactosyl and arabinosyl. In addition, it also contains a small amount of fucose, xylose and glucose. Soybean polysaccharide has a special spherical structure, so it has low viscosity, good thermal stability; molding auxiliary material additive; anti-adhesion; anti-freezing; inhibition of starch regeneration and the like, so it has been widely used in food.

[0024] The composite system prepared by the present invention through soybean seed coat polysaccharide emulsion and sodium stearoyl lactylate effectively inhibits the retrogradation problem of prefabricated starch products and can extend the shelf life of flour-based foods. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The sensory evaluation of the dough produced in Examples 1-3 of the present invention and Comparative Example 1;

[0026] Figure 2 The dough hardness analysis of the dough produced in Examples 1-3 of the present invention and Comparative Example 1 during storage at 4°C;

[0027] Figure 3 The change in the regeneration enthalpy of the dough produced in Examples 1-3 of the present invention and Comparative Example 1 during storage at 4°C;

[0028] Figure 4 The moisture content of the dough produced by Examples 1-3 of the present invention and Comparative Example 1 during storage at 4°C;

[0029] Figure 5 Dough creep changes of dough skins produced in Examples 1-3 of the present invention and Comparative Example 1;

[0030] Figure 6 (A) is a relationship diagram between the dough frequency and the storage modulus of the dough skins produced in Examples 1-3 of the present invention and Comparative Example 1; (B) is a relationship diagram between the dough frequency and the loss modulus of the dough skins produced in Examples 1-3 of the present invention and Comparative Example 1; (C) is a relationship diagram between the dough frequency and the loss angle of the dough skins produced in Examples 1-3 of the present invention and Comparative Example 1.

[0031] Figure 7 Scanning electron microscope images of dough produced in Examples 1-3 of the present invention and Comparative Example 1 (AD in the figure represent Comparative Example 1, Example 2, Example 1, and Example 3, respectively) DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments.

[0033] A method for preparing an emulsion for inhibiting starch retrogradation, comprising the following steps:

[0034] Step 1: heating and melting the soybean seed coat polysaccharide, wherein the heating temperature of the soybean seed coat polysaccharide is 65-70° C.; the heating method of the soybean seed coat polysaccharide is water bath heating; and the heating time of the soybean seed coat polysaccharide is 2-3 hours;

[0035] Step 2: adding soybean oil to the melted soybean seed coat polysaccharide, dispersing and homogenizing to obtain a soybean seed coat polysaccharide emulsion, wherein the soybean oil addition amount is 1-2%, and high-speed shearing is performed at 12000 rpm for 2 minutes;

[0036] Step 3: allowing the soybean seed coat polysaccharide emulsion to stand for 10-14 hours;

[0037] Step 4: Add sodium stearoyl lactylate to the soybean seed coat polysaccharide emulsion, and stir in a 60° C. water bath until uniformly dispersed to form a soybean seed coat polysaccharide-sodium stearoyl lactylate (SHP-SSL) composite emulsion.

[0038] Embodiment 1:

[0039] This embodiment provides sample 1, which is prepared according to the above method, wherein the added amount of soybean seed coat polysaccharide is 0wt%; the added amount of sodium stearoyl lactylate is 1wt%.

[0040] Embodiment 2:

[0041] This embodiment provides sample 2, which is prepared according to the above method, wherein the added amount of soybean seed coat polysaccharide is 0.8wt%; the added amount of sodium stearoyl lactylate is 0.2wt%.

[0042] Embodiment 3:

[0043] This embodiment provides sample 3, which is prepared according to the above method, wherein the added amount of soybean seed coat polysaccharide is 1wt%; and the added amount of sodium stearoyl lactylate is 0wt%.

[0044] Comparative Example 1:

[0045] Blank group: no SHP-SSL composite emulsion was added.

[0046] Experimental example:

[0047] Performance Testing

[0048] The examples 1-3 and comparative example 1 were respectively mixed with flour in a ratio of 1:45-1:50, and steamed for later use.

[0049] 1. Sensory Evaluation

[0050] Organize 10 trained laboratory personnel to conduct sensory evaluation on the color, appearance, smoothness, stickiness and taste of the dough of Examples 1-3 and Comparative Example 1 according to the evaluation criteria in Table 1.

[0051] Table 1 Sensory scoring index of the products in the embodiment

[0052]

[0053]

[0054] The results are as follows Figure 1 As shown, compared with comparative example 1, the score of Example 2 is 83 points, which is the highest in the group. In terms of appearance, comparative example 1 has the lowest score, with uneven condensation and small holes on the surface of the dough. Example 2 has the highest score, with a smooth surface and a dense structure, and no holes or pores are observed visually. In terms of color, comparative example 1 has the highest color score, which is white and similar to the color of flour, giving people a visual comfort. Example 3 has the lowest score, which is largely related to the dark color of the homemade SHP itself. In terms of toughness, comparative example 1 has the worst toughness and poor chewiness, while example 2 has the best toughness. In terms of smoothness in taste, comparative example 1 has the lowest score. Steamed dough has a certain toughness and is more difficult to chew than boiled dough. The addition of additives can make the chewing taste softer, which is consistent with the conclusion of dough creep. In terms of taste, according to the scoring criteria, example 3 only has the fragrance of wheat flour alone. Example 2 and example 1 scored second, because in addition to the fragrance of wheat flour, there is also a relatively light sweetness.

[0055] In summary, the treatment group that gave the best mouth feel and comfort was Example 3.

[0056] 2. Texture test analysis

[0057] The dough skins prepared in Examples 1-3 and Comparative Example 1 were stored at 4°C for 1, 4, 7, 14, and 21 days. The gel was taken out and balanced at room temperature for 30 minutes before testing. The texture characteristics of the dough skin of the starch gel were measured using a physical property tester. The measurement program was TPA mode, the probe model was P / 36R, and the trigger type was set to "Au-to". The measurement conditions were as follows: pre-measurement rate 2 mm / s, test rate 1 mm / s, post-measurement rate 1 mm / s, compression degree 60.0%, trigger force 5.0 g, time interval 5.00 s, and compression 2 times.

[0058] like Figure 2As shown, with the increase of storage time, the hardness values ​​of Examples 1-3 and Comparative Example 1 all show an increasing trend, but at the same storage time, the hardness values ​​of Examples 1, 2, and 3 are significantly lower than the finished dough of Comparative Example 1. It is shown that the addition of SHP-SSL reduces the hardness and viscosity of the dough, which is beneficial to the subsequent storage and processing of the dough. This is because SHP-SSL has good water retention, reduces the water loss during the dough heat processing, and because SHP-SSL is wrapped around the starch granules, the expansion of the starch granules is inhibited, and the increase in viscosity during the gelatinization process is limited. In addition, the addition of SHP-SSL increases the cohesion of the dough, which may be due to the electrostatic action of the anionic groups in the composite system structure of SHP and SSL and the amino groups in the gluten protein to form a gluten protein-polysaccharide complex, thereby improving the gluten protein structure. In addition, the repulsion between the negative charges of SHP itself disperses its molecular chains, which are easily adsorbed with protein particles and entangled with starch molecular chains, thereby promoting the spatial continuity of the molecular network structure, making the dough tissue fine and dense, and helping to improve the processing performance of the dough.

[0059] 3. Determination of thermal properties

[0060] About 10 mg of the dough samples prepared in Examples 1-3 and Comparative Example 1 were weighed into an aluminum crucible solid plate and sealed using a tablet press, with an empty aluminum plate as a reference. The sample plate was heated from 25° C. to 125° C. at a heating rate of 10° C. / min. The thermal enthalpy value (ΔH) was calculated using the system's own software based on the DSC thermal curve.

[0061] like Figure 3 As shown in the figure, with the increase of storage time, the ΔH values ​​required for the recrystallization of melted amylopectin in the flour (WF) of Comparative Example 1 and Examples 1, 2, and 3 all showed a significant growth trend. The retrogradation enthalpy of the dough skin after refrigeration for 7 days increased from 0.52 J / g to 1.22 J / g, and ΔH was 0.79 J / g. The retrogradation enthalpy of the dough skin of Example 2 after refrigeration for 7 days increased from 0.21 J / g to 0.5 J / g, and ΔH was 0.29 J / g. By comparison, it can be seen that the growth rate of the retrogradation enthalpy of the dough skin added with Examples 1, 2, and 3 is less than that of Comparative Example 1, indicating that SHP-SSL has a significant inhibitory effect on the retrogradation of wheat starch. This may be because SHP-SSL has strong hydrophilicity and can bond with starch side chains, thereby increasing the steric hindrance of starch and preventing starch molecules from combining in a hydrogen bond manner, making it difficult for them to be oriented and arranged to form a crystal structure. During the entire storage time of 21 days, the ΔH value of the solution with SHP addition was higher than that of the SSL solution. This may be because soybean oil and SSL as lipid emulsifiers can serve as a barrier for moisture distribution, thereby limiting the flow of amylose during storage and inhibiting retrogradation.

[0062] 4. Determination of moisture content

[0063] Referring to the method of GB5009.3-2016, the moisture content of the dough prepared in Examples 1-3 and Comparative Example 1 was determined by direct drying method, and each sample was placed in an electric hot air drying oven at 105°C and dried to constant weight (the difference in mass before and after was no more than 2 mg). The ratio of the mass difference of the sample before and after drying to the mass of the original sample was used to calculate the moisture content.

[0064] like Figure 4 As shown in the figure, the total water content of all samples did not change significantly during the storage process, indicating that water loss was not the cause of dough recovery. However, at the same storage time, the water content of Examples 1, 2, and 3 was significantly higher than that of Comparative Example 1, indicating that the water content of the dough skin with SHP-SSL was significantly higher. As is known to all, an important mechanism by which SHP and SSL can be used as dough skin improvers is that both SHP and SSL can reduce the water loss of the dough skin during storage and maintain the shape of the dough skin.

[0065] 5. Dough rheology analysis

[0066] 1. Dough creep measurement and analysis

[0067] The dough prepared in Examples 1-3 and Comparative Example 1 was placed on a 40 mm parallel plate at 25°C for measurement. An appropriate amount of sample was placed on a sample table with a slit spacing of 2 mm. The dough was subjected to a constant stress creep test of 100 Pa, and then the stress was removed. The relaxation of the dough was restored within 600 seconds. The deformation was calculated based on the data of the obtained creep recovery curve.

[0068] like Figure 5 As shown in the figure, in the creep stage, the creep strain of the dough increases with the increase of SHP addition, indicating that the dough with SHP addition is easy to deform under the action of external stress, and SHP increases the softness of the dough, which is consistent with the conclusion of texture analysis. When the amount of SHP added increases from 0.2g to 1g, the creep of the dough increases by 50%, and is lower than the creep strain of the control sample (5%). The creep strain is closely related to the moisture content of the dough. Generally, the dough with higher moisture content has a larger maximum creep strain. SHP has a higher water absorption rate due to the large number of hydroxyl groups, which allows more water molecules to bind to SHP through hydrogen bonds, increasing the competition between SHP and other ingredients (such as protein and starch) for water, and ultimately affecting the moisture distribution in the dough.

[0069] 6. Dough frequency scanning analysis

[0070] The dough prepared in Examples 1-3 and Comparative Example 1 was placed on a 40 mm parallel plate at 25°C for measurement. An appropriate amount of sample was placed on a sample table with a slit spacing of 2 mm. The sample was first subjected to strain scanning (0.01%-100%) to determine the linear viscoelastic region. The strain was selected to be 0.5% and the frequency range was 0.1-10 Hz. The changes in the storage modulus (G'), loss modulus (G") and tanδ of the sample with the scanning frequency were recorded.

[0071] Figure 6 Storage modulus (G′), loss modulus (G″) and loss angle (tanδ) of the dough of Examples 1, 2, 3 and Comparative Example 1. It can be seen from the figure that G′ and G″ increase with increasing frequency, and G′ of the dough is greater than G″ (tanδ<1), indicating that the dough exhibits semi-solid partial elastic properties. It can be seen from the figure that tanδ of Examples 1, 2, 3 is lower than that of Comparative Example 1, indicating that SHP-SSL with different mass ratios can increase the content and degree of polymerization of the polymer in the dough and enhance the gluten network structure of the dough.

[0072] 7. Scanning electron microscopy analysis

[0073] The dough samples prepared in Examples 1-3 and Comparative Example 1 were freeze-dried, ground into powder using a mortar, attached to a scanning electron microscope sample plate using double-sided tape, and the excess powder was blown off using a dust blower. The sample plate was subjected to gold spraying for 15 minutes using a sputtering coating machine. The microstructure of the dried starch gel powder was observed using a SEM analyzer at 2 kV and 1500× magnification.

[0074] like Figure 7 As shown, the scanning electron microscope image of the dough magnified 15K. AD is Comparative Example 1, Example 2, Example 1, and Example 3, respectively. The addition of additives enables the samples to form a certain film structure. The addition of SHP and SHP-SSL resulted in a thicker sheet structure. This may be because the treatment group containing SHP has the strongest hydration, thus forming the most developed network structure. SHP is a linear nonionic hydrophilic colloid that can form a network structure with gluten protein through hydrogen bonds. The sample with SSL added formed a thinner film structure. The structure formed is not as stable as the treatment group containing SHP, which can be intuitively explained through the photos.

[0075] According to the performance test, all the embodiments have the effect of inhibiting the regeneration of dough skin, among which the effect of inhibiting the regeneration of dough skin in embodiment 2 is the best, so the optimal solution is selected, the addition amount of soybean seed coat polysaccharide is 0.8wt%, and the addition amount of sodium stearoyl lactylate is 0.2wt%.

[0076] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. 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. An emulsion for inhibiting starch retrogradation, characterized in that: The emulsion comprises a composite emulsion prepared from soybean seed coat polysaccharide and sodium stearoyl lactylate.

2. The emulsion for inhibiting starch retrogradation according to claim 1, characterized in that: The mass percentage of the soybean seed coat polysaccharide and the sodium stearoyl lactylate added is 0:1-1:

0.

3. The emulsion for inhibiting starch retrogradation according to claim 1, characterized in that: The composite emulsion is added with 1-2% by mass of soybean oil.

4. A method for preparing the emulsion for inhibiting starch retrogradation according to any one of claims 1 to 3, characterized in that: The steps include: Step 1, heating and melting soybean seed coat polysaccharide; Step 2, adding soybean oil to the melted soybean seed coat polysaccharide, dispersing and homogenizing, and obtaining a soybean seed coat polysaccharide emulsion; Step 3, storing the soybean seed coat polysaccharide emulsion for a period of time; Step 4: Add sodium stearoyl lactylate to the soybean seed coat polysaccharide emulsion and stir at a certain temperature until it is evenly dispersed to form an emulsion.

5. The emulsion for inhibiting starch retrogradation according to claim 4, characterized in that: In step 1, the addition amount of the soybean testa polysaccharide is 0-1wt%; the heating temperature of the soybean testa polysaccharide is 65-70°C; the heating method of the soybean testa polysaccharide is water bath heating; and the heating time of the soybean testa polysaccharide is 2-3h.

6. The emulsion for inhibiting starch retrogradation according to claim 4, characterized in that: In step 2, the soybean oil is added in an amount of 1-2%, and high-speed shearing is performed at 12000 rpm for 2 minutes.

7. The emulsion for inhibiting starch retrogradation according to claim 4, characterized in that: In step 3, the soybean seed coat polysaccharide emulsion is kept still for 10-14 hours, and the resting temperature of the soybean seed coat polysaccharide is 4°C.

8. The emulsion for inhibiting starch retrogradation according to claim 4, characterized in that: In step 4, the addition amount of sodium stearoyl lactylate is 0-1wt%, and the stirring temperature is 60-65°C.

9. Use of the emulsion for inhibiting starch retrogradation according to any one of claims 1 to 3 in the field of food, characterized in that: include: During the pasta making process, the emulsion is added to the dough.

10. The use of the emulsion for inhibiting starch retrogradation according to claim 9, characterized in that: The mass ratio of the emulsion to the dough is 1:45-1:50.

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