Preparation method and application of starch-lipid compound

Abstract

The invention belongs to the technical field of food processing, and particularly relates to a preparation method and application of a starch-lipid compound. The starch-lipid compound is prepared by taking mung bean starch, lauric acid, ethanol and water as raw materials and adopting a low-temperature plasma method. The preparation method comprises the following steps: firstly, preparing mung bean starch into a starch suspension with water, and then adding lauric acid dissolved in ethanol into starch milk to prepare a mixed suspension; then carrying out low-temperature plasma treatment at the temperature lower than the starch gelatinization temperature so as not to generate gelatinization phase change, and then preparing a starch-lauric acid compound suspension through hot bath; and finally, washing, drying and sieving the suspension to obtain the novel starch lipid compound. The starch-lauric acid compound prepared by the method can slow down the enzyme digestion speed, has the characteristics of easy preparation and separation, low cost, low energy consumption, reduced viscosity, aging resistance, retrogradation inhibition, good thermal stability, digestion resistance and the like, and has wide application prospects in the fields of food processing and functional food.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of food processing, and particularly relates to a preparation method of starch-lipid complex and application thereof. BACKGROUND

[0002] The starch-lipid complex is a new type of modified starch with excellent performance, which is formed by combining the fatty chains of oil or fatty acid in the internal cavity of the straight-chain helix of starch through hydrogen bond, hydrophobic interaction, van der Waals force and other forces, belongs to the fifth type of resistant starch, and the hydrophilic groups of the lipid are exposed outside the helix due to steric hindrance and electrostatic repulsion. The complex changes the structure, properties and physiological functions of the original starch, not only makes the solubility and swelling power low, the anti-digestive ability strong, and the thermal stability good, but also can delay the aging of starch, greatly changes the digestibility of the original starch, and simultaneously improves the content of slow-digesting starch and resistant starch. Therefore, as a new type of modified starch, it has become a research hotspot of scholars at home and abroad, and shows unique advantages in food industry application and improvement of human sub-health. If it is applied to cereal products and other starch foods, it is expected to bring good edible value, especially for the groups of diabetic patients and patients with intestinal diseases, and has very broad application prospect.

[0003] Nowadays, the development of starch-lipid complex preparation is highly valued in the industry and has broad prospects. However, the current preparation method in China is mostly to use pure amylose, debranched starch or rely on the gelatinization state to prepare the complex. Common methods include hydrothermal method, melting method, extrusion method, etc. Although the RS content of the gelatinized complex prepared in this way increases, the physical properties often deteriorate. Because the gelatinization process destroys the crystalline region of the particles, resulting in insufficient oil holding capacity (gelatinized state ≤ 30%, granular state ≥ 60%), poor emulsion stability (centrifugal stratification time < 2h, granular state > 8h), etc. At the same time, gelatinization forms a continuous gel structure, limiting its application scenarios, such as not being able to be directly compressed into tablets as a solid powder (gelatinized state angle of repose > 50°), and melting and sticking to the roller during thermal processing (granular melting temperature can be increased by 15-20℃). The gelatinized starch-lipid complex prepared by hydrothermal treatment is mainly type I complex with weak enzyme resistance, and there are problems such as lipid aggregation, deterioration of gelatinization properties and thermal stability, and high temperature treatment during processing, which may damage heat-sensitive ingredients, all of which affect its application in food processing. In addition, the existing preparation method often uses irritating chemical reagents or is carried out at a high reaction temperature, which has the problems of long time-consuming, difficulty in separation and extraction, high cost, high energy consumption, etc., which is not conducive to industrial production. Therefore, it is urgent to develop an efficient and green new process for the production of starch-lipid complex, and further research is needed to study the factors affecting its stability and properties, and to develop new starch products with environmental protection, safety, non-toxicity, low cost, strong processing adaptability and good functional properties (such as anti-aging, slow release and lipid stability) to broaden the application range of starch. In this context, the method of complexing starch with fatty acids without gelatinization, which can reduce the possibility of performance deterioration, has gradually entered people's field of vision. In many scenarios, the role of granular starch and fatty acid complex is particularly important. For example: when delaying starch aging and inhibiting starch retrogradation to extend the shelf life of bread; when improving texture (such as bread softness); when processing at room temperature and fast processing to produce pre-mixed flour and instant soup; when preserving the granular structure to achieve thickening and excipient effects; when reducing the oil penetration of surface lipids (such as producing low oil absorption potato chips); when making flavor substance microcapsules at room temperature; when making drug sustained-release particles; and when making slow-release carbohydrate foods with moderate sugar control, it can effectively make up for the shortcomings of ordinary starch and gelatinized starch-lipid complex.

[0004] In recent years, the study of granular starch-lipid complex has gradually attracted attention. This method does not need to separate amylose or prepare debranched starch / starch paste. It only needs to make starch granules in the swollen state to complex with lipids, and then the product is recovered and dried appropriately to form a granular starch-lipid complex. However, this method of complexing at a lower temperature has a low efficiency, and therefore it is urgent to explore a more efficient method for preparing a granular starch-lipid complex. At present, there are mainly two methods for preparing a granular starch-lipid complex in the laboratory: the first method needs to pretreat starch. Although the pretreated starch is not completely gelatinized and still retains the granular morphology, its physicochemical properties have changed. Unlike the original starch granules, this method uses the solubility of granular starch in cold water to complex with lipids at a lower temperature of 20-60°C to form a complex. However, the preparation of granular starch is usually complicated, requires high equipment, and needs to use a large amount of alcohol reagent and / or alkali solution, and has problems such as complex process, long time consumption, and large loss. The second method uses the traditional hydrothermal method to heat the starch at a temperature slightly lower than its gelatinization temperature (generally at 80-90°C) for a period of time to make the starch swell, and then add lipids for complexing reaction. Although this method has a low requirement for equipment, it is not suitable for embedding heat-sensitive substances due to the high reaction temperature, and it is easy to cause uneven complexing. If the water bath temperature is reduced, the swelling degree of starch will decrease, and thus the complexing efficiency with lipids will decrease. In addition, the production efficiency of the granular complex prepared by high pressure and irradiation technology still needs to be improved. Therefore, finding a suitable method to improve the complexing effect of the granular complex method has become a research demand in recent years.

[0005] At the same time, low-temperature plasma has entered the public view and is increasingly used in the field of food processing due to its green, low-carbon, efficient, non-thermal processing, and harmless to food safety. The high-energy active particles generated by plasma can cause the molecular chain of starch to break, making the molecular weight smaller and the distribution wider. The degree of degradation of starch will continuously increase with the strengthening of plasma action. In this case, it is appropriate to use it to prepare a granular starch-lipid complex.

[0006] The special surface modification (such as etching effect), high reactivity, and non-thermal effect of low-temperature plasma make it a new technology and method for food modification and processing. It can improve the gelatinization characteristics of starch, increase the thermal stability and resistant digestion starch content, and enhance the anti-enzymatic potential of traditional starch-lipid complex. However, there is no related technology for preparing a granular starch-fatty acid complex as a high-resistant starch by using low-temperature plasma in the prior art. SUMMARY

[0007] In order to overcome the above-mentioned deficiencies of the prior art, the present application provides a method for preparing starch-lipid complex, which is pretreated by low-temperature plasma to improve the resistant content, anti-aging performance and processing adaptability of starch by using the etching effect thereof. Meanwhile, the granular starch-lauric acid complex prepared by the method has the characteristics of easy preparation and separation, environmental friendliness, low cost, low energy consumption, anti-digestion, anti-aging and strong processing adaptability.

[0008] In order to achieve the above-mentioned purpose, the technical scheme adopted by the present application is: The present application provides a method for preparing starch-lipid complex, which comprises the following steps: S1, dissolving mung bean starch in water to prepare starch milk, then adding lauric acid dissolved in ethanol, and then performing low-temperature plasma treatment below the starch gelatinization temperature (To) so that no gelatinization phase transition occurs (i.e. the starch exists in the form of particles); the power of the low-temperature plasma treatment is 20-120 W, and the time is 7-15 min; S2, performing water bath treatment on the suspension after the low-temperature plasma treatment, and then performing washing and drying to obtain the starch-lauric acid complex.

[0009] The present application develops a new method for efficiently preparing starch-lipid complex, and different starch-lipid complex products with different resistant starch contents can be obtained by adjusting process parameters. Due to the difference in resistant starch content, these complex products can significantly affect various characteristics of starch-based food: in terms of sensory quality, the texture and taste can be improved; in terms of storage characteristics, the shelf life can be prolonged; in terms of nutritional function, the digestion rate can be adjusted. More importantly, the series of complex products prepared by the method can be accurately added according to the specific needs of different foods, which provides new raw material selection and technical support for the development of functional food.

[0010] Preferably, in S1, the power of the low-temperature plasma treatment is 60-80 W.

[0011] Preferably, in S1, the mass concentration of the starch milk prepared from mung bean starch is 8-15%, and the mass concentration of lauric acid is 5-7% based on the dry starch basis.

[0012] Preferably, in S1, the temperature of the low-temperature plasma treatment is 40-60 ℃.

[0013] Preferably, in S2, the temperature of the water bath treatment is 55-60 ℃, and the time is 1-2 h.

[0014] Preferably, in S2, the washing is 3-5 times of washing of the suspension with anhydrous ethanol-water solution with a volume ratio of 1:1.

[0015] Preferably, in S2, the dried starch is further sieved to 90-110 mesh.

[0016] Preferably, the drying temperature is 40-50℃, and the drying time is 20-30h.

[0017] The second aspect of the present application provides the starch-lipid complex prepared by the method of the first aspect.

[0018] The starch-lipid complex prepared by the present application belongs to the fifth resistant starch (RS5), and the structural feature is that the amylose and the lipid form a helical complex through hydrophobic interaction. The complex can significantly improve the crystalline structure and short-range order of the starch while maintaining the morphology of the starch granules. The changes in these structural properties will directly affect the functional properties of the starch, thereby expanding its application value in the food industry, including but not limited to: improving the sensory and storage quality of food, serving as a functional starch substitute, and providing a source of resistant starch, etc.

[0019] The third aspect of the present application provides the use of the starch-lipid complex of the second aspect in the preparation of anti-digestion food.

[0020] Compared with the prior art, the present application has the following advantages: The present application discloses a method for preparing a starch-lipid complex, which uses mung bean starch, lauric acid, ethanol and water as raw materials and adopts a low-temperature plasma method. First, the mung bean starch is mixed with water to form a starch suspension, and then lauric acid dissolved in ethanol is added to the starch milk to form a mixed suspension. Then, the low-temperature plasma treatment is carried out below the starch gelatinization temperature (To), so that the starch does not undergo gelatinization phase transition (i.e., the starch exists in the form of particles). Then, the starch-lauric acid complex suspension is prepared by hot water bath. Finally, after washing, drying and sieving, a new starch-lipid complex with high resistant content is obtained. The starch-lauric acid complex prepared by the method of the present application can slow down the enzyme digestion rate, and has the characteristics of easy preparation and separation, low cost, low energy consumption, reduced viscosity, anti-aging, inhibition of retrogradation, good thermal stability, anti-digestion, etc., and has a wide application prospect in the field of food processing and functional food.

[0021] Specifically, the present application has the following advantages: (1) The starch-lipid complex with different resistant starch content can be efficiently prepared by changing the conditions of low-temperature plasma treatment, which has potential wide application value in the field of food.

[0022] (2) The starch-lauric acid emulsion is treated by low-temperature plasma, and then a starch-lipid complex is prepared by a hydrothermal method. The low-temperature plasma treatment has a certain degree of depolymerization effect on starch chains, and can effectively improve the content of lipids in the complex product. In addition, the low-temperature plasma treatment can also improve the pasting properties of the granular complex, such as anti-aging, inhibition of starch retrogradation, improvement of thermal stability, improvement of anti-digestion capacity, etc.

[0023] (3) After the starch is treated by low-temperature plasma, amylose and amylopectin will be degraded, and the degree of polymerization (chain length) of the starch will be reduced. Among them, the degradation of amylopectin can reduce its hindering effect on the complex of amylose and lipids; the decrease of the chain length of amylose (within a certain degree of polymerization) is also conducive to the formation of an ordered crystal structure, thereby enhancing the stability of the amylose-lipid complex. Compared with the existing preparation method of granular starch-lauric acid complex, the method of the present application can overcome the technical defects of the need for a large amount of ethanol solution and high-temperature conditions for pretreatment, and the operation is relatively complicated. The method has the advantages of easy preparation and separation, low cost, low energy consumption, and few reaction by-products, etc., and meets the requirements of green manufacturing technology.

[0024] (4) Low-temperature plasma technology is a green, low-carbon, non-thermal processing high-tech, and plasma is harmless to food safety. Therefore, it is theoretically feasible to use low-temperature plasma combined with a hydrothermal method to prepare a granular starch-lipid complex. This method will help to open up a new green and efficient production technology for granular starch-lipid complex.

[0025] (5) The starch-lipid complex prepared by the method of the present application does not need to separate amylose or prepare debranched starch or starch paste, and the starch granules are in an expanded state for complex reaction with lipids. The product can be recovered and dried appropriately, and the process is simple, the preparation process is pollution-free, the time consumption is relatively short, and the production cost is relatively low. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 X-ray diffraction patterns of samples of Examples 1-6 and Comparative Examples 1-2; Figure 2 Pasting property test results of samples of Examples 1-6 and Comparative Examples 1-2; Figure 3 Thermal property curves of samples of Examples 1-6 and Comparative Examples 1-2. DETAILED DESCRIPTION

[0027] The specific embodiments of the present application are further described below. It should be noted that the description of these embodiments is intended for purposes of illustration only and is not intended to be limiting. Furthermore, the features of various embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0028] The experimental methods in the following examples are all conventional methods unless otherwise specified. The experimental materials used in the following examples are all commercially available unless otherwise specified.

[0029] The starch particles and fatty acids selected in Examples 1-6 and Comparative Examples 1-3 below are selected from mung bean starch and lauric acid, respectively. The mung bean starch is self-made by the water milling method in the laboratory: after soaking, milling, filtering, precipitating, washing, drying, grinding, and sieving, mung bean starch is obtained, and the specific operation method is referred to “Gao QY, Huang LX, Zhou JX. Preliminary study on soaking process of mung bean and pea starches extracted by water milling method[J]. Journal of Zhengzhou Grain College, 1998, 19(4):5. DOI:CNKI:SUN:ZZLS.0.1998-04-009.”

[0030] Example 1: A preparation method of a mung bean starch-lauric acid complex, comprising the following steps: (1) 10 g of mung bean starch is accurately weighed and mixed with 90 mL of distilled water to prepare a starch suspension (10%, w / w), then 0.6 g of lauric acid is dissolved in 3 mL of anhydrous ethanol (6%, w / w, based on the dry starch basis), and then added to the starch milk.

[0031] (2) At a temperature lower than the gelatinization temperature (To) of the starch, a low-temperature plasma treatment device (Nanjing Sumen Plasma Technology Co., Ltd., Nanjing, China) is used for low-temperature plasma treatment. The sample is placed between two electrodes covered with an insulating quartz layer for reaction. During the reaction, an intelligent peristaltic pump (LLS Plus; Caleva Fluid Technology Co., Ltd., Shanghai, China) is used to circulate the sample in the cooling water and the reaction vessel to control the temperature of the sample system below 60°C (usually controlled between 40-60°C), so that the sample does not undergo gelatinization phase transition (i.e., the starch remains in the form of particles), and the power of the low-temperature plasma is set to 20 W, the treatment time is 9 min, and after treatment, the sample is placed in a 60°C magnetic stirring water bath for water bath for 1 h.

[0032] (3) After water bath, the suspension was washed with 1:1 volume ratio of absolute ethanol-water solution for 3 times (4000 rpm centrifugation for 10 min each time), and then dried at 40 ℃ for 24 h, sieved through 100 mesh sieve, and finally the granular green bean starch lauric acid complex was obtained, named as MBS-LA-20.

[0033] Example 2: The preparation steps were basically the same as those of Example 1, except that the power of the low-temperature plasma was replaced by 40 W, and the green bean starch lauric acid complex was obtained, named as MBS-LA-40.

[0034] Example 3: The preparation steps were basically the same as those of Example 1, except that the power of the low-temperature plasma was replaced by 60 W, and the green bean starch lauric acid complex was obtained, named as MBS-LA-60.

[0035] Example 4: The preparation steps were basically the same as those of Example 1, except that the power of the low-temperature plasma was replaced by 80 W, and the green bean starch lauric acid complex was obtained, named as MBS-LA-80.

[0036] Example 5: The preparation steps were basically the same as those of Example 1, except that the power of the low-temperature plasma was replaced by 100 W, and the green bean starch lauric acid complex was obtained, named as MBS-LA-100.

[0037] Example 6: The preparation steps were basically the same as those of Example 1, except that the power of the low-temperature plasma was replaced by 120 W, and the green bean starch lauric acid complex was obtained, named as MBS-LA-120.

[0038] Comparative Example 1: The preparation steps were basically the same as those of Example 1, except that the power of the low-temperature plasma was replaced by 0 W, i.e. no low-temperature plasma treatment was performed, and the granular sample obtained after treatment was named as MBS-LA.

[0039] Comparative Example 2: A preparation method of a green bean starch-lauric acid complex (hydrothermal method), comprising the following steps: (1) 10 g of green bean starch was accurately weighed and mixed with 90 mL of distilled water to prepare a starch suspension (10%, w / w, based on the dry starch basis), and then 0.6 g of lauric acid was dissolved in 3 mL of absolute ethanol (6%, w / w, based on the dry starch basis) and added to the starch milk.

[0040] (2) Put the prepared starch milk into the 80 ℃ magnetic stirring water bath for 60 min.

[0041] (3) After water bath, wash the suspension with 1:1 volume ratio of anhydrous ethanol-water solution for 3 times, freeze-dry for 48 h, crush through a 100 mesh sieve, and finally obtain the gelatinized green bean starch lauric acid complex, named MBS-LA-Δ.

[0042] Comparative Example 3: MBS is the original green bean starch granules.

[0043] Experimental Example: Characteristic Determination of Green Bean Starch-Lauric Acid Complex (1) Determination of Complex Index of Green Bean Starch-Lauric Acid Complex Accurately weigh 0.2 g (dry basis) of sample, disperse it into 20 mL of distilled water, and vortex to mix the solution thoroughly. Then place it in a boiling water bath, heat and stir for 15 min until the sample is completely gelatinized. After the gelatinized sample cools down, add 30 mL of distilled water, vortex for 1 min, and centrifuge at 5000 r / min for 10 min. Take 1 mL of supernatant, add 1 mL of iodine solution (containing KI 2.0 g, I2 1.3 g, and 100 mL of distilled water) and 8 mL of distilled water in sequence, vortex again for 1 min, and mix to develop color. Take the sample without fatty acid as a control, measure the absorbance at 690 nm, and calculate the complex index (CI) according to the following formula: ; Wherein, Ac is the absorbance value of the control group, and As is the absorbance value of MBS-LA complex.

[0044] (2) Determination of Crystallinity of Green Bean Starch-Lauric Acid Complex Determine the crystalline structure change of green bean starch or starch-lauric acid complex at 40 kV voltage and 40 mA current by X-ray diffraction method. Scan the sample in the range of 3°-60° (2θ) with a speed of 2° / min and a step of 0.02° using Cu-Kα radiation, analyze the X-ray diffraction (XRD spectrum) of the sample, and calculate the relative crystallinity (RC) according to the following formula: ; Wherein, Ac represents the area of the crystalline region in the X-diffraction pattern, and Aa represents the area of the amorphous region.

[0045] (3) Determination of Gelatinization Properties of Green Bean Starch-Lauric Acid Complex A certain mass of sample (with mung bean starch as control) was mixed with 25 mL of deionized water in an aluminum box of a rapid viscosity analyzer (RVA) to make a solution with a concentration of 6% (w / w, dry basis). Then the sample was measured for paste curve according to the standard 2 in RVA to obtain the pasting properties of mung bean starch and mung bean starch-lauric acid complex.

[0046] (4) Determination of thermal stability of mung bean starch-lauric acid complex The thermal properties of the sample were determined by differential scanning calorimeter. 3 mg of sample (dry basis) was added to an aluminum crucible, and distilled water was added to the sample at a mass ratio of sample: water = 1:3. After sealing, it was stored at room temperature for 24 h. Then the test was carried out according to the following conditions: using an empty disc as a control, the temperature was raised from 30 ℃ to 110 ℃ at a heating rate of 10 ℃ / min.

[0047] (5) Determination of digestion properties of mung bean starch-lauric acid complex Accurately weigh 100 mg of sample and disperse it in 10 mL of acetic acid-sodium acetate buffer (0.5 mol / L, pH=5.2), mix thoroughly, and after pasting for 30 min, place the sample in a 37 ℃ water bath shaker for 10 min; add 4 mL of porcine pancreatic protease (3000 μ / mL) and 1 mL of saccharifying enzyme (2500 μ / mL), and then shake the reaction. Take 0.2 mL of reaction solution at 0 min, 40 min, 60 min, 90 min, 120 min and 180 min, respectively, and after boiling in a water bath for 5 min, determine the glucose content in the supernatant using DNS color reagent. The RDS, SDS and RS contents of mung bean starch and mung bean starch-lauric acid complex were calculated, and the calculation formula is as follows: ; ; .

[0048] In the formula, G0, G20 and G120 are the percentages of glucose at 0 min, 20 min and 120 min, respectively.

[0049] 2. Results and discussion 2.1. Determination results of complex index of mung bean starch-lauric acid complex Table 1 shows that the composite index of the particulate composite prepared by low-temperature plasma treatment is higher than that of the gelatinized composite prepared by hydrothermal method. Furthermore, after treatment with low-temperature plasma at a certain power, the composite index (CI) of the particulate mung bean starch-lauric acid composite is significantly improved, increasing from 41.45% without low-temperature plasma treatment to 59.09% with 80 W low-temperature plasma treatment, representing a maximum increase of 16.65%. Moreover, different low-temperature plasma treatment powers have a significant impact on the efficiency of mung bean starch binding to lauric acid (p < 0.05). The composite effect of mung bean starch and lauric acid is most significantly improved when the plasma treatment power is 60 W and 80 W, indicating that low-temperature plasma treatment can effectively increase the LA content in the composite product.

[0050] Table 1. Composite Index (CI) of Different Samples 2.2 Results of Crystallinity Determination of Mung Bean Starch-Lauric Acid Complex The particulate composite without low-temperature plasma preparation exhibits a C-type crystal structure, similar to that of legume starch. The starch-lauric acid composite prepared by low-temperature plasma also exhibits a C-type crystal structure. This indicates that neither low-temperature plasma treatment nor the addition of lauric acid alters the crystal form of the particulate starch, and both show strong diffraction peaks near 5.6°, 15°, 17°, 19°, 23°, and 26°. Figure 1 The gelatinized complex prepared by the hydrothermal method exhibited a V-shaped crystal structure, with a significant change in crystal form. Simultaneously, the addition of fatty acids led to a significant decrease in the crystallinity of starch. The gelatinized complex had the lowest crystallinity at 27.06%, while the crystallinity of the particulate complex decreased from 45% in the particulate starch to approximately 30%. This indicates that low-temperature plasma treatment further reduces the crystallinity of the complex; for example, at treatment powers of 40 W and 80 W and a treatment time of 9 min, the crystallinity of the complex could be reduced to approximately 28%, and different treatment powers had a significant impact on the crystallinity of the particulate sample (p < 0.05).

[0051] 2.3 Results of the determination of the gelatinization characteristics of mung bean starch-lauric acid complex like Figure 2As shown in Table 2, the pasting curves of the granular complex prepared by low-temperature plasma treatment of starch changed significantly. The pasting curves of mung bean starch, starch-LA complex prepared by hydrothermal method and granular starch-LA complex without low-temperature plasma treatment showed a downward trend after reaching the peak, while the complex prepared by low-temperature plasma treatment tended to be stable. After LA complexation, the peak viscosity of the pasting complex increased significantly, while the peak viscosity of the granular complex was lower than that of mung bean starch, and basically showed a downward trend with the increase of power. Unlike this single change trend, the trough viscosity of the granular starch-LA complex showed a trend of first decreasing and then increasing with the increase of low-temperature plasma power, while the trough viscosity of the pasting starch increased significantly. At the same time, the attenuation value of the starch-LA complex also showed a trend of first decreasing and then increasing, and the attenuation degree of MBS-LA-60 was the lowest (153.00 cP), while the attenuation degree of MBS-LA-20 was the largest (391.50 cP). The attenuation value of the pasting complex was also lower than that of the original mung bean starch, but was significantly higher than that of the granular starch-lauric acid complex. The final viscosity of the complex was higher than that of the original starch, the final viscosity of the pasting complex was the highest, which was significantly higher than that of the original starch and the granular complex, and the final viscosity of the granular complex showed a trend of first increasing and then decreasing with the increase of low-temperature plasma treatment power. In addition, the setback value and pasting temperature of the starch-LA complex were greater than MBS, and the pasting temperature of the pasting complex was significantly lower than that of the original mung bean starch and the granular complex (p<0.05). Overall, the granular starch-LA complex can better improve the pasting properties of the sample compared with the original mung bean starch and the pasting complex, especially the complex prepared by low-temperature plasma treatment.

[0052] Table 2 RVA parameters of starch samples 2.4, determination results of thermal stability of mung bean starch-lauric acid complex In Figure 3In Table 3, the starch granules complexed with LA increased the peak II, and the To of the complex was significantly increased from 57.87 °C of MBS to about 70 °C, while the To of the paste state was lower than that of the original mung bean starch; the Tc of the paste state complex decreased significantly, while the granular state complex had no significant change; indicating that the etching effect produced by low temperature plasma destroyed the weak crystal structure in the starch granules, and a higher temperature was needed to dissociate its strong crystal structure. In the second peak, the peak temperature (Tp) of the granular state complex was slightly lower than that of the paste state complex, and the enthalpy change (ΔH) was also slightly lower than that of the paste state complex; the To of the granular state complex was slightly higher than that of the paste state, and the Tc was slightly lower than that of the paste state complex. Overall, the granular starch-LA complex can improve the thermal stability of the sample, especially the complex prepared under low temperature plasma treatment.

[0053] Table 3 DSC parameters of starch samples 2.5、Mung bean starch-lauric acid complex digestion characteristics test results As shown in Table 4, the mung bean starch complexed with LA can significantly improve the resistant starch content of the sample (p<0.05), from 54.30% of MBS to about 60%; although the resistant content of the granular complex is slightly lower than that of the paste state complex, the resistant content of the granular complex treated by low temperature plasma is significantly improved than that of MBS-LA; at the same time, the total content of slow digestion starch and resistant digestion starch also significantly increases (p<0.05).

[0054] Table 4 Digestion characteristics parameters of starch samples In summary, low-temperature plasma has a certain degree of degradation effect on starch chains, which can effectively increase the content of LA in the complex product, with the highest increase of 16.65%; the crystallinity of the complex prepared by low-temperature plasma is slightly higher than that of the gelatinized starch-lipid complex, and appropriate low-temperature plasma treatment conditions can further reduce the crystallinity of the complex, but it is still higher than that of the gelatinized state preparation; at the same time, low-temperature plasma treatment can improve the paste characteristics of the complex, delay starch aging, inhibit starch, and also improve the thermal stability; most importantly, it can improve the digestion resistance of starch and complex, so that it can be better applied in the field of food processing and functional food. For example, by delaying starch aging and inhibiting retrogradation, the shelf life of bread and other foods can be extended, and the texture can be improved (such as improving the softness of bread); it can meet the needs of normal temperature processing and rapid processing, and is convenient for the production of pre-mixed flour, instant soup and other products; it can retain the granular structure, thereby achieving thickening and excipient effects; it can reduce the oil penetration of surface lipids, and is suitable for the production of low oil absorption potato chips; it can also be used for the production of microcapsules by embedding flavor substances at room temperature, or for the production of drug sustained-release particles by controlling the release rate. In addition, in terms of sugar control, it can help to make sustained-release carbohydrate foods, effectively making up for the shortcomings of ordinary starch and gelatinized starch-lipid complex.

[0055] The embodiments of the present application are described in detail above, but the present application is not limited to the described embodiments. For those skilled in the art, various changes, modifications, replacements and variations of the embodiments can be made without departing from the principles and spirits of the present application, and still fall within the protection scope of the present application.

Claims

1. A method for the preparation of starch-lipid complexes, characterized in that, The method comprises the following steps: S1, dissolving mung bean starch in water to prepare starch milk, then adding lauric acid dissolved in ethanol, and then performing low-temperature plasma treatment below the starch gelatinization temperature to prevent the starch from undergoing gelatinization phase transition; the power of the low-temperature plasma treatment is 20-120 W, and the time is 7-15 min; S2, performing water bath treatment on the suspension after the low-temperature plasma treatment, and then performing washing and drying to obtain the starch-lauric acid compound.

2. A process for the preparation of a starch-lipid complex according to claim 1, characterized in that, In S1, the power of the low-temperature plasma treatment is 60-80 W.

3. The method for preparing a starch-lipid complex according to claim 1, characterized in that, In S1, the mass concentration of the starch milk prepared from mung bean starch is 8-15%, and the mass concentration of lauric acid is 5-7% based on the dry starch.

4. The method for preparing a starch-lipid complex according to claim 1, characterized in that, In S1, the temperature of the low-temperature plasma treatment is 40-60 ℃.

5. The method for preparing a starch-lipid complex according to claim 1, characterized in that, In S2, the temperature of the water bath treatment is 55-60 ℃, and the time is 1-2 h.

6. The method for preparing a starch-lipid complex according to claim 1, characterized in that, In S2, the washing is performed by using anhydrous ethanol-water solution with a volume ratio of 1:1 to wash the suspension for 3-5 times.

7. The method for preparing a starch-lipid complex according to claim 1, characterized in that, In S2, after drying, the starch-lauric acid compound still needs to be sieved through a 90-110 mesh sieve.

8. The starch-lipid compound prepared by the method of claim 1.

9. The use of the starch-lipid compound of claim 8 in the preparation of anti-digestion food.

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