Preparation method and application of allulose-vanillin microcapsules

Abstract

The application discloses a preparation method and application of allulose-vanillin microcapsules, and comprises a double emulsion preparation step, an alternating current field treatment step and a spray drying step. By constructing a double water-in-oil-in-water emulsion, the problems of low solubility and poor stability of the material are solved, and the bioavailability of allulose and vanillin is improved. The allulose-vanillin microcapsules are prepared by using alternating current field superimposed spray drying, the adsorption and combination of allulose and vanillin molecules on the water-oil phase are strengthened, and the encapsulation rate and the retention rate of vanillin are effectively improved. The preparation method provided by the application aims to reduce the sucrose content in food by using cross-modal interaction, realizes the goal of reducing sugar without reducing sweetness of food, solves the problems of insufficient sweetening effect and limited microcapsule embedding efficiency of flavor substances in the prior art, and has a wide market application prospect in the field of food processing.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of food processing, in particular to a preparation method of allulose-vanillin microcapsules for reducing sugar and increasing sweetness and application thereof. BACKGROUND

[0002] Sugar plays a crucial role in most foods as a flavoring agent, and is also an important determinant of whether a product is accepted by consumers. However, high-sugar diets are directly related to the incidence of "lifestyle diseases" such as cardiovascular disease, diabetes, and cancer. For decades, countries around the world have been emphasizing the harmfulness of high-sugar diets to human public health. Therefore, how to reduce free sugar in food while not reducing the level of consumer eating experience and preference, that is, to achieve "reducing sugar without reducing sweetness", has become a major challenge faced by the global food industry. In order to meet the needs of consumers for new healthy foods, the development of healthy, low-sugar and delicious foods has become a research hotspot in the food processing industry, especially the research and exploration of green and natural sugar reduction strategies.

[0003] Allulose is a new natural sweetener, which has about 70% of the sweetness of sucrose and only 0.4% of the energy of sucrose, and can be used as an ideal substitute for sucrose in candies or beverages. In June 2012, the U.S. Food and Drug Administration (FDA) officially listed allulose as "generally recognized as safe" (GRN No. 400), and authorized its use as an ingredient in a variety of foods and dietary supplements. Related studies have shown that allulose not only can significantly reduce postprandial blood glucose levels and insulin concentrations, but also has multiple effects such as reducing fat, preventing atherosclerosis, etc. However, the use of allulose alone to replace sucrose in sugar-reduced food formulations can easily result in a loss of sweetness perception.

[0004] Cross-modal sensory interactions are usually mediated by multisensory synergies, including vision, touch, smell, hearing, and taste. Odor, taste, and oral tactile sensation not only independently affect food flavor perception, but also can enhance flavor perception through cross-channel sensory interactions. Studies have shown that cross-modal interactions between smell and taste based on sweet-related food characteristic aromas can enhance sweet perception. When there is a sensory similarity between odor and taste, odor can enhance taste, therefore, it is necessary to compensate for the sweetness perception intensity of sugar-reduced foods through cross-modal interactions between odor and taste.

[0005] Vanillin is the main source of vanilla flavor, which can give consumers a strong "sweet taste". Based on cross-modal interaction, the combination of allulose and vanillin in the field of food can make up for the loss of flavor in the process of food sugar reduction, and is a more natural sugar reduction strategy. At present, the common method is to start from a single aqueous solution, and dissolve allulose and vanillin in water at the same time. Although the operation process is simple, it is accompanied by the disadvantages of low solubility and poor stability of the substances, which makes the bioavailability of allulose and vanillin low, and the sweetening effect of vanillin cannot be fully exerted. Microencapsulation is a technology that can improve the water solubility of natural active substances and improve their bioavailability. Encapsulating allulose and vanillin with microencapsulation technology can achieve better stability and applicability. At present, the method for preparing microcapsules is to use traditional spray drying technology, and the uniform droplets are sprayed into the drying chamber by airflow, and then dried to form microcapsule powder. This method is simple to operate and suitable for large-scale production, but the adsorption and combination ability between substances is limited, the embedding efficiency is low, and the high temperature generated in the spray drying process often destroys the molecular forces between the emulsions, causing the retention rate of the substances to be significantly reduced. Practice has proved that the combination ability of allulose and vanillin molecules is poor, the retention rate of vanillin is low, and the problems of insufficient sweetening effect and limited embedding efficiency of flavor substances are common when using traditional spray drying technology to prepare allulose-vanillin microcapsules.

[0006] Therefore, it is necessary to develop a new preparation method of allulose-vanillin microcapsules to overcome the above-mentioned defects. SUMMARY

[0007] Therefore, the purpose of the present application is to provide a preparation method of allulose-vanillin microcapsules, which can improve the superposition and compounding effect of allulose and vanillin, enhance the cross-modal interaction of odor-taste, fully exert the sweetening effect of vanillin, and solve the major problems of insufficient sweetening effect of allulose-vanillin microcapsules and limited embedding efficiency of flavor substances.

[0008] In order to achieve the above-mentioned purposes, the technical scheme adopted by the present application is:

[0009] A preparation method of allulose-vanillin microcapsules, comprising:

[0010] Step S1, preparing a double emulsion:

[0011] (I) Preparation of water-in-oil emulsion W1 / O: 0.04-0.12wt% vanillin and 1.0-3.0wt% polyglycerol ricinoleate are dissolved in sunflower oil, the ratio of oil phase to water phase is controlled to be 8:2, the water phase is deionized water, the coarse emulsion is homogenized by a handheld homogenizer at 6000-10000 rpm for 2 min, and then placed in an ultrahigh pressure homogenizer for homogenization at 600 bar for 1.5 min to obtain a W1 / O emulsion;

[0012] (II) Preparation of water-in-oil-in-water emulsion W1 / O / W2: 3.0wt% allulose and 4-8wt% large yellow croaker lecithin are dissolved in the external water phase W2, then the W1 / O emulsion and the external water phase W2 are mixed at a water / oil phase ratio of 2:8, 3:7 or 4:6 v / v, and homogenized by an ultrahigh pressure homogenizer at 40-80 MPa for 1-2 min to obtain a W1 / O / W2 emulsion;

[0013] Step S2, AC electric field treatment: the W1 / O / W2 emulsion obtained in step S1 is placed in an AC electric field device, the frequency of the AC electric field is set to 50 Hz, the voltage is 110-260 V, the application time limit of 110-170 V is 3-5 s, the application time limit of 170-230 V is 1-3 s, and the application time limit of 260 V is 1-2 s;

[0014] Step S3, spray drying: the W1 / O / W2 emulsion treated in step S2 is placed in a spray drying device for spray drying to obtain an allulose-vanillin microcapsule powder.

[0015] Further, the process parameters of the spray drying are: heating temperature 120℃, inlet air temperature 70-90℃, outlet air temperature 60-70℃, peristaltic pump flow rate 15-20g / min, spray and needle pressure 0.3Mpa.

[0016] Further, the large yellow croaker lecithin is prepared by the following method: dry large yellow croaker roe is added to 95% ethanol and stirred at room temperature for 2h to obtain a leaching solution, the material liquid ratio of large yellow croaker roe to 95% ethanol is 1:8g / ml; the leaching solution is treated by rotary evaporation at 40℃ until the 95% ethanol is fully volatilized to obtain large yellow croaker roe oil; the components of the large yellow croaker roe oil are dissolved in n-hexane, 4℃ cold acetone is added at a material liquid ratio of 1:3v / v, and the mixture is placed in a-18℃ refrigerator for 12h to obtain a white precipitate of large yellow croaker lecithin; the supernatant is discarded and 4℃ cold acetone is added to re-dissolve, and the above operation is repeated for 3 times; finally, the acetone and the precipitate are separated under the condition of rotary evaporation at 40℃ to obtain paste-like large yellow croaker lecithin, which is dried with nitrogen for 1h to obtain dry large yellow croaker lecithin, which is stored in a-20℃ refrigerator for standby use.

[0017] The above technical solution has the following beneficial effects:

[0018] 1. Unlike the existing single aqueous solution form, the present application solves the problems of low solubility and poor stability of the substances by constructing a double water-in-oil-in-water emulsion, and distributing the vanilla flavor substances (vanillin) directly related to sweetness and allulose into different water / oil phases, thereby improving the bioavailability of allulose and vanillin.

[0019] 2. Unlike the traditional spray drying method for preparing microcapsules, the double emulsion constructed by the present application is subjected to alternating electric field modification treatment before spray drying, which strengthens the adsorption and combination of allulose and vanillin molecules on the water / oil phase, makes the combination of allulose and vanillin molecules on the water / oil phase more closely, effectively improves the retention rate of vanillin. On this basis, spray drying treatment is carried out again, which can reduce the negative impact of high temperature processing on the retention rate of vanillin, improve the flavor enhancement effect of allulose-vanillin microcapsules, and effectively improve the encapsulation efficiency.

[0020] 3. The present application uses large yellow croaker lecithin as an emulsifier. The large yellow croaker lecithin has a high content of polyunsaturated fatty acids, and has a strong ability to combine free radicals, that is, good antioxidant property. Compared with common emulsifiers such as malt dextrin and sodium alginate, the large yellow croaker lecithin can greatly improve the nutritional efficacy of allulose-vanillin microcapsules, and can inhibit the oxidation reaction caused by high temperature during the spray drying process to a certain extent, thereby further improving the vanillin retention rate and stability of allulose-vanillin microcapsules.

[0021] In summary, the method of the present application solves the problems of low solubility and poor stability of substances when allulose and vanillin are used together, maximizes the sweetness enhancement effect of vanillin, and solves the major problems of insufficient sweetness enhancement effect of allulose-vanillin microcapsules and limited flavor substance microcapsule embedding efficiency. The allulose-vanillin microcapsules prepared by the method of the present application have good stability, good processing and storage properties, and can be conveniently applied in the form of powder during food processing, effectively reducing free sugar in food while not reducing the eating experience of consumers, truly realizing "reducing sugar without reducing sweetness", and having broad market application prospects in the field of food processing. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 The figure shows the sensory evaluation radar chart of the samples prepared in Example 1 and Comparative Examples 1-3 of the present application. DETAILED DESCRIPTION

[0023] It should be noted that all the directionality indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present application are only used to explain the relative position relationship, movement condition, etc. between components in a certain specific posture (as shown in the drawings), and if the specific posture changes, the directionality indications will also change accordingly.

[0024] In addition, the descriptions such as "first", "second" and the like in the present application are only for the purpose of description, and cannot be understood as indicating or implying the relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first", "second" can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise specifically limited.

[0025] Sugar plays an important role in food production and processing, can effectively produce sweetness and affect the mouthfeel and satisfaction of consumers to food. But high-sugar diet can bring many negative effects on human health, and it is urgent to develop healthy, low-sugar and delicious food. In addition, the efficient microencapsulation of flavor substances has become a major problem plaguing the food industry. In view of the above problems, the present application aims to reduce the sucrose content in food by using cross-modal interaction, achieve the goal of "reducing sugar without reducing sweetness" of food, and solve the problems of insufficient sweetening effect and limited microencapsulation efficiency of flavor substances in the prior art.

[0026] Specifically, the preparation method of the allulose-vanillin microcapsule provided by the present application comprises:

[0027] Step S1, preparing a double emulsion:

[0028] (I) preparing a water-in-oil emulsion W1 / O: dissolving 0.04-0.12wt% vanillin and 1.0-3.0wt% polyglycerol ricinoleate in sunflower oil, controlling the ratio of oil phase to water phase to be 8:2, the water phase is deionized water, the coarse emulsion is homogenized by a handheld homogenizer at 6000-10000rpm for 2min, and then put into an ultrahigh pressure homogenizer, homogenized at 600bar for 1.5min to obtain a W1 / O emulsion;

[0029] (II) preparing a water-in-oil-in-water emulsion W1 / O / W2: dissolving 3.0wt% allulose and 4-8wt% large yellow croaker lecithin in the outer water phase W2, then mixing the W1 / O emulsion and the outer water phase W2 according to the water / oil phase ratio of 2:8, 3:7 or 4:6v / v, and homogenizing by an ultrahigh pressure homogenizer at 40-80MPa for 1-2min to obtain a W1 / O / W2 emulsion;

[0030] Step S2, AC electric field treatment: the W1 / O / W2 emulsion obtained in step S1 is placed in an AC electric field device, the AC electric field frequency is set to 50 Hz, the voltage is 110-260 V, the application time limit of 110-170 V is 3-5 s, the application time limit of 170-230 V is 1-3 s, and the application time limit of 260 V is 1-2 s;

[0031] Step S3, spray drying: the W1 / O / W2 emulsion treated in step S2 is placed in a spray drying device for spray drying to obtain an allulose-vanillin microcapsule powder.

[0032] In the above embodiment, as a preferred embodiment, the process parameters of the spray drying are as follows: heating temperature 120℃, inlet air temperature 70-90℃, outlet air temperature 60-70℃, peristaltic pump flow rate 15-20 g / min, spray and needle pressure 0.3 Mpa.

[0033] In the above embodiment, as a preferred embodiment, the large yellow croaker lecithin is prepared by the following method: dry large yellow croaker roe is added to 95% ethanol and stirred at room temperature for 2 h to obtain an extraction solution, the solid-liquid ratio of the large yellow croaker roe to 95% ethanol is 1:8 g / ml; the extraction solution is subjected to rotary evaporation at 40℃ until the 95% ethanol is fully volatilized to obtain large yellow croaker roe oil; the components of the large yellow croaker roe oil are dissolved in n-hexane, 4℃ cold acetone is added at a solid-liquid ratio of 1:3 v / v, and the mixture is placed in a-18℃ refrigerator for 12 h to obtain a white precipitate of large yellow croaker lecithin; the supernatant is discarded and 4℃ cold acetone is added to re-dissolve, and the above operation is repeated for 3 times; finally, the acetone and the precipitate are separated under the condition of rotary evaporation at 40℃ to obtain paste-like large yellow croaker lecithin, which is dried with nitrogen for 1 h to obtain dry large yellow croaker lecithin, which is stored in a-20℃ refrigerator for standby use.

[0034] Specifically, the technical principle of the present application is as follows:

[0035] The sweetness of allulose is about 70% of sucrose, and if only allulose is used to replace sucrose in the formula of reduced-sugar food, the sensory loss of sweetness of the product is easy to occur. Therefore, it is necessary to compensate for the sweetness perception intensity of reduced-sugar food through the cross-modal interaction between odor and taste. In the existing technology, allulose and vanillin are often dissolved in water at the same time from the form of a single aqueous solution, although the operation process is simple, but it is accompanied by the disadvantages of low solubility and poor stability of the substances. The present application improves the bioavailability of allulose and vanillin by constructing a double water-in-oil-in-water emulsion, and distributing the vanilla flavor substances (vanillin) directly related to sweetness and allulose into different water / oil phases. At the same time, there is a direct relationship between the retention rate of vanillin and the perception of sweetness intensity. The traditional spray drying method often destroys the molecular forces between emulsions due to high temperature treatment, resulting in a significant decrease in the retention rate of the substances. In the present application, alternating current field modification technology is added. The principle of this technology is that the molecular forces between emulsions are mainly hydrogen bonds. When the electric field force intervenes, the charge carriers in the molecule begin to move. The movement of free electrons or charged ions makes the combination of allulose and vanillin molecules on the water / oil phase more closely, effectively improving the retention rate of vanillin. On this basis, spray drying treatment can reduce the negative impact of high temperature processing on the retention rate of vanillin, and improve the flavor enhancement effect of allulose-vanillin microcapsules.

[0036] In addition, the key to affecting the retention rate of vanillin is not only the physical factor condition in the spray drying process. From a chemical point of view, the microcapsule wall material in the emulsion is also crucial. Unlike the commonly seen malt dextrin and sodium alginate products on the market, the large yellow croaker egg lecithin extracted from large yellow croaker eggs has a high content of polyunsaturated fatty acids, and has a strong ability to combine free radicals, that is, good antioxidant property, which gives the fish egg lecithin higher nutritional value, and can inhibit the oxidation reaction caused by high temperature in the spray drying process to a certain extent, thereby further improving the vanillin retention rate and stability of the microcapsule product.

[0037] From the above description, the present application has the following beneficial effects:

[0038] 1. Unlike the existing single aqueous solution form, the present application solves the problems of low solubility and poor stability of substances by constructing a double water-in-oil-in-water emulsion, and distributing the vanilla flavor substances (vanillin) directly related to sweetness and allulose into different water / oil phases, thereby improving the bioavailability of allulose and vanillin.

[0039] 2. Unlike traditional spray-drying methods for preparing microcapsules, the dual emulsion constructed in this invention undergoes pre-treatment with an alternating electric field before spray drying. This enhances the adsorption and binding forces of allulose and vanillin molecules on the water / oil phase, resulting in a tighter bond between the allulose and vanillin molecules and effectively improving vanillin retention. Furthermore, the subsequent spray-drying process reduces the negative impact of high-temperature processing on vanillin retention, improves the flavor enhancement effect of the allulose-vanillin microcapsules, and effectively increases the encapsulation efficiency.

[0040] 3. This invention utilizes large yellow croaker lecithin as an emulsifier. Large yellow croaker lecithin has a high content of polyunsaturated fatty acids, which have a strong ability to bind free radicals, i.e., good antioxidant properties. Compared with commonly used emulsifiers such as maltodextrin and sodium alginate, it can greatly improve the nutritional efficacy of allulose-vanillin microcapsules. Moreover, large yellow croaker lecithin can inhibit the oxidation reaction caused by high temperature during spray drying to a certain extent, thereby further improving the vanillin retention rate and stability of allulose-vanillin microcapsules.

[0041] The following are several preferred embodiments or application embodiments to help those skilled in the art better understand the technical content of the present invention and the technical contributions made by the present invention compared with the prior art:

[0042] Example 1:

[0043] Step 1: Extraction of large yellow croaker lecithin (LYCRPLs): Weigh 80g of dried large yellow croaker roe, add 95% ethanol (solid-liquid ratio 1:8g / ml), stir at room temperature for 2h, and then rotary evaporate the extract at 40℃ until the 95% ethanol is fully evaporated to obtain large yellow croaker roe oil. Dissolve the large yellow croaker roe oil in n-hexane, add cold acetone (4℃) at a solid-liquid ratio of 1:3v / v, and let stand in a -18℃ refrigerator for 12h to obtain a white precipitate of LYCRPLs. Discard the supernatant and redissolve it in cold acetone at 4℃. Repeat the above operation 3 times. Finally, separate the acetone from the precipitate under rotary evaporation at 40℃ to obtain a paste-like LYCRPLs. Dry it with nitrogen for 1h to obtain dried LYCRPLs, which are stored in a -20℃ refrigerator for later use.

[0044] Step 2, Preparation of the double emulsion:

[0045] (i) Water-in-oil (W1 / O) emulsion: Vanillin (0.06 wt%) and polyglyceryl ricinoleate PGPR (2.5 wt%) were dissolved in sunflower oil to prepare the oil phase. The ratio of oil phase to water phase (deionized water) was set to 8:2. The coarse emulsion was homogenized by a hand-held homogenizer at 8000 rpm for 2 min, and then the coarse emulsion was put into an ultra-high pressure homogenizer to be homogenized at 600 bar for 1.5 min to obtain the W1 / O emulsion.

[0046] (ii) Water-in-oil-in-water (W1 / O / W2) emulsion: Allulose (3.0 wt%) and LYCRPLs (8 wt%) were fully dissolved in W2. Subsequently, the W1 / O emulsion obtained in the above method was mixed with the external water phase W2 (3:7, v / v). The W1 / O / W2 emulsion was obtained by an ultra-high pressure homogenizer at 60 MPa for 1 min.

[0047] Step 3, AC electric field treatment: The W1 / O / W2 emulsion obtained in Step 2 was placed in an AC electric field device, and the frequency of the AC electric field was 50 Hz. The application time limit was 4.0 s at 150 V, 2.0 s at 200 V, and 2.0 s at 260 V.

[0048] Step 4, spray drying: The allulose-vanillin emulsion collected in Step 3 was placed in a spray drying device, and the heating temperature was controlled at 120°C, the inlet air temperature was 80°C, the outlet air temperature was 65°C, the peristaltic pump flow rate was 17 g / min, and the spray and needle pressure was 0.3 MPa.

[0049] Step 5, packaging: The allulose-vanillin microcapsule powder obtained in Step 4 was packaged and sealed under dry and sterile conditions to obtain the finished product.

[0050] Example 2

[0051] The same as Example 1, except that 50 g of dried large yellow croaker roe was weighed in Step 1, and the feed liquid ratio of 95% ethanol was 1:6 g / ml. In Step 2(i), the addition amount of vanillin was 0.04 wt%, the addition amount of PGPR was 1.0 wt%, and the rotation speed of the hand-held homogenizer was set to 6000 rpm; in Step 2(ii), the mixing ratio of W1 / O to W2 was 2:8, and the treatment conditions of the ultra-high pressure homogenizer were 40 MPa for 2 min. In Step 3, the application time limit was 5.0 s at 110 V, 3.0 s at 170 V, and 2.0 s at 260 V. In Step 4, the inlet air temperature of the spray drying device was 70°C, the outlet air temperature was 60°C, and the peristaltic pump flow rate was 15 g / min.

[0052] Example 3

[0053] Other than Example 1, the difference is that 100 g of dried large yellow croaker roe is weighed in step 1, and the feed liquid ratio of 95% ethanol is 1:10 g / ml. In step 2 (I), the addition amount of vanillin is 0.12 wt%, and the addition amount of PGPR is 3.0 wt%, and the rotation speed of the handheld homogenizer is set to 10000 rpm; In step 2 (II), the mixing ratio of W1 / O and W2 is 4:6, and the processing condition of the ultra-high pressure homogenizer is 80 MPa, 1 min. In step 3, the application time limit of 170V is 3.0s, the application time limit of 230V is 1.0s, and the application time limit of 260V is 1.0s. In step 4, the inlet air temperature of the spray drying equipment is 90℃, the outlet air temperature is 70℃, and the flow rate of the peristaltic pump is 20 g / min.

[0054] Comparative Example 1

[0055] Other than Example 1, the difference is that step 3 is not performed.

[0056] Comparative Example 2

[0057] Other than Example 1, the difference is that in step 2 (II), the lecithin extracted in step 1 is not used as an emulsifier, and soybean phospholipid (SPLs) is used as an emulsifier.

[0058] Comparative Example 3

[0059] Other than Example 1, the difference is that in step 2 (I), the addition of vanillin is not performed.

[0060] The particle size, PDI and vanillin retention rate of the samples obtained in the examples and comparative examples of the present application are determined. Each test is determined in parallel for 3 times, and the results are expressed as "average value ± standard deviation".

[0061] Particle size, PDI determination method: After the sample to be measured is diluted with deionized water according to the ratio of 1:500 (v / v), it is placed into the laser particle size instrument measuring pool, and the particle size and PDI of the emulsion are measured by dynamic light scattering. The refractive indices of the water phase and the oil phase are set to 1.333 and 1.476 respectively, and the determination operation is repeated three times.

[0062] Vanillin standard curve establishment method: 96% ethanol is used as the solvent to prepare vanillin standard solutions of different concentrations (0.002-0.01 mg / ml, w / v). The absorbance at 310 nm is measured to establish the vanillin standard curve. The linear regression equation obtained is as follows:

[0063] y = 77.582x + 0.0016 (R 2 = 0.9998)

[0064] Vanillin retention rate determination method: 0.2 g of sample was mixed with 20 ml of 96% ethanol, and placed in a constant temperature oscillator at 37°C with 180 rpm oscillation for 1 h, and then avoided light and placed for 1 h. All solutions were centrifuged at 4000 rpm for 10 min, and the supernatant was collected, and the absorbance at 310 nm was determined by ultraviolet spectrophotometer. The vanillin retention rate in the sample was calculated according to the standard curve, and was calculated according to the following formula:

[0065] Vanillin retention rate (%) = m1 / m0 x 100

[0066] Wherein m1 is the vanillin content in the microcapsule sample, and m0 is the total amount of vanillin added in the initial preparation. The results are shown in Table 1:

[0067] Table 1 Physical properties of allulose-vanillin microcapsules

[0068]

[0069] Note: Different letters indicate significant differences between groups (P<0.05)

[0070] From Table 1, it can be seen that compared with the comparative example, the particle size and PDI of examples 1-3 treated by alternating electric field are significantly lower than those of comparative example 1 (P<0.05), and lower particle size and PDI value represent that the sample has better storage stability. At the same time, the vanillin retention rate of the examples is significantly higher than that of comparative example 1 (P<0.05), indicating that superimposing alternating electric field treatment before spray drying treatment can promote the movement of charged particles between molecules, effectively improve the retention rate of vanillin, and improve the sweet taste perception enhancement effect of allulose-vanillin microcapsules.

[0071] Fatty acid composition determination method: The unsaturated fatty acid composition of the sample was determined by gas chromatography, and the nutritional efficacy was compared. 20.0-50.0 mg of sample was dissolved in 1 ml of sodium hydroxide-methanol (2 mol / L), and placed in a 60°C water bath for 2 min, then 1 ml of hydrochloric acid (2 mol / L) was added to the solution and incubated for 5 min. Finally, 2 ml of n-hexane was added, and the mixture was placed at room temperature for 1 h, and the upper n-hexane containing fatty acid methyl esters was collected, dried with anhydrous sodium sulfate, and then analyzed for fatty acid composition. The specific operating conditions of the equipment are as follows: the column temperature is 80°C, maintained for 3 min, then increased to 175°C at a rate of 20°C / min, maintained for 10 min, and finally increased to 250°C at a rate of 4°C / min, maintained for 20 min. The carrier gas is nitrogen, the flow rate is 1.0 ml / min, the injection volume is 1.0 μl, and the split ratio is 50:1. Each test was determined in triplicate, and the results were expressed as "mean ± standard deviation". The specific results are as follows:

[0072] Table 2 Unsaturated fatty acid composition of allulose-vanillin microcapsules

[0073]

[0074] Note: Different letters indicate significant differences between groups (P < 0.05)

[0075] As can be seen from Table 2, compared with Comparative Example 2, the content of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in all examples has been significantly improved (P < 0.05), which is believed to be due to the difference in the content of LYCRPLs in the technical scheme formula. As we all know, EPA and DHA are essential ingredients for human nutrition. However, the synthesis of EPA and DHA in the human body is slow, but they can be directly taken from food. Therefore, compared with Comparative Example 2 using SPLs, the examples using LYCRPLs as emulsifiers in the formula can provide more nutrients to the human body and have higher nutritional value.

[0076] Sensory evaluation method: 24 sensory analysts (aged 21-29 years old) were recruited from the laboratory to form a group to conduct sensory evaluation. The sensory evaluation members first conducted olfactory evaluation before each sensory evaluation, scored the vanilla and butter smell of each sample (1-10), then rinsed their mouth with distilled water, sipped 5ml of the sample in the oral cavity for 15s, fully experienced the taste, spit it out, rinsed their mouth with distilled water and scored the sweetness, vanilla and butter of the sample. Distilled water was used to rinse between two sample evaluations and a 5-minute rest time was provided to keep the mouth clean and reduce the influence between samples. The results are shown in Figure 1

[0077] As can be seen from Figure 1 , the sweetness evaluation of the examples is better than that of Comparative Example 3 without adding vanillin, indicating that the presence of odor substances is crucial in the process of sugar reduction, vanillin has a significant cross-modal effect on the perception of product sweetness intensity, the addition of vanillin increases the rating of sweetness intensity, and the sugar reduction based on cross-modal interaction is a more green and healthy strategy.

[0078] In summary, from the analysis results between Comparative Examples 1-3 and Examples, it can be seen that the interaction between the operation procedures of the present application is indispensable, and if one of the procedures is omitted, it may affect the stability, nutritional value or sweetness enhancement effect of the allulose-vanillin microcapsules.

[0079] ​In summary, the method of the present application solves the problems of low solubility and poor stability of the existing combination of allulose and vanillin, maximizes the sweetening effect of vanillin, and solves the major problems of insufficient sweetening effect of allulose-vanillin microcapsules and limited microcapsule embedding efficiency of flavor substances. The allulose-vanillin microcapsules prepared by the method of the present application have good stability, good processing and storage properties, and can be conveniently applied in the form of powder during food processing, effectively reducing the free sugar in food while not reducing the eating experience of consumers, truly realizing "reducing sugar without reducing sweetness", and having wide market application prospect in the field of food processing.

[0080] The present application has been described by the above related embodiments and drawings, however, the above embodiments are only examples for implementing the present application. It must be pointed out that the disclosed embodiments do not limit the scope of the present application. On the contrary, modifications and equal arrangements included in the spirit and scope of the claims are included in the scope of the present application.

Claims

1. A method for preparing allulose-vanillin microcapsules, characterized by, Comprise: Step S1, preparing double emulsion: (I) preparing water-in-oil emulsion W1 / O: 0.04-0.12wt% vanillin and 1.0-3.0wt% polyglycerol ricinoleate are dissolved in sunflower oil, the ratio of oil phase to water phase is controlled to be 8:2, the water phase is deionized water, the coarse emulsion is homogenized by a handheld homogenizer at 6000-10000rpm for 2min, and then placed in an ultrahigh pressure homogenizer for homogenization at 600bar for 1.5min to obtain a W1 / O emulsion; (II) preparing water-in-oil-in-water emulsion W1 / O / W2: 3.0wt% allulose and 4-8wt% large yellow croaker lecithin are dissolved in the external water phase W2, then the W1 / O emulsion and the external water phase W2 are mixed according to the water / oil phase ratio of 2:8, 3:7 or 4:6 v / v, and homogenized by an ultrahigh pressure homogenizer at 40-80MPa for 1-2min to obtain a W1 / O / W2 emulsion; Step S2, alternating current field treatment: the W1 / O / W2 emulsion obtained in step S1 is placed in an alternating current field device, the alternating current field frequency is set to 50Hz, the voltage is 110-260V, the application time limit of 110-170V is 3-5s, the application time limit of 170-230V is 1-3s, and the application time limit of 260V is 1-2s; Step S3, spray drying: the W1 / O / W2 emulsion treated in step S2 is placed in a spray drying device for spray drying to obtain an allulose-vanillin microcapsule powder; The process parameters of the spray drying are: heating temperature 120℃, inlet air temperature 70-90℃, outlet air temperature 60-70℃, peristaltic pump flow rate 15-20g / min, and spray and needle pressure 0.3Mpa.

2. The preparation method of allulose-vanillin microcapsules according to claim 1, characterized in that, The large yellow croaker lecithin is prepared by the following method: dry large yellow croaker roe is added to 95% ethanol and stirred at room temperature for 2h to obtain a leaching solution, the material liquid ratio of large yellow croaker roe to 95% ethanol is 1:8g / ml; the leaching solution is treated by rotary evaporation at 40℃ until the 95% ethanol is fully volatilized to obtain large yellow croaker roe oil; the components of the large yellow croaker roe oil are dissolved in n-hexane, 4℃ cold acetone is added at a material liquid ratio of 1:3 v / v, and the mixture is placed in a-18℃ refrigerator for 12h to obtain a white precipitate of large yellow croaker lecithin; the supernatant is discarded and 4℃ cold acetone is added for re-dissolution, and the above operation is repeated for 3 times; finally, the acetone and the precipitate are separated by rotary evaporation at 40℃ to obtain a paste-like large yellow croaker lecithin, which is dried with nitrogen for 1h to obtain dry large yellow croaker lecithin, which is stored in a-20℃ refrigerator for standby use.

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