Tamarind polysaccharide gel as well as preparation method and application thereof

Abstract

The invention provides tamarind polysaccharide gel and a preparation method and application thereof.The preparation method of the tamarind polysaccharide gel comprises the following steps that S1, beta-galactosidase is added into a tamarind polysaccharide aqueous solution, alcohol precipitation and drying are performed after enzymolysis and enzyme deactivation, and tamarind polysaccharide subjected to enzyme treatment is obtained; wherein the enzymolysis time is 1 to 2 hours; s2, adding the tamarind polysaccharide subjected to enzyme treatment into an ethanol water solution, and stirring to obtain a mixed solution; wherein the volume ratio of the ethanol in the mixed solution is less than or equal to 15%; s3, refrigerating the mixed solution to obtain the tamarind polysaccharide gel. According to the method, stable gel can be formed under the condition of low ethanol content, the irritation of the product is reduced, the strength of the gel can be considered, and the application range of the tamarind polysaccharide can be expanded.

Description

Technical Field

[0001] This invention belongs to the field of food colloid technology, specifically relating to a tamarind polysaccharide gel, its preparation method, and its application. Background Technology

[0002] Traditional tamarind polysaccharide gels typically require high concentrations of ethanol (>20%) to form a stable structure, resulting in a highly irritating product with low consumer acceptance. On the one hand, high ethanol content may trigger regulatory standards for alcoholic beverages, limiting the consumer base and increasing compliance costs; on the other hand, a strong alcoholic odor can affect the acceptability of food flavors, and high volatility requires more stringent packaging conditions.

[0003] While enzymatic modification can optimize polysaccharide properties in existing technologies, it lacks specific design for low-ethanol gel systems, making it difficult to balance the requirements of low ethanol content and high gel strength. Furthermore, the market for alcoholic solid beverages (such as alcoholic sago) lacks products that are low in calories, low in irritants, and have excellent taste. Therefore, developing a low-ethanol, high-strength gel technology is of great significance for expanding the application of tamarind polysaccharides in the food industry. Summary of the Invention

[0004] In view of this, the present invention provides a tamarind polysaccharide gel, its preparation method and application, which can form a stable gel under low ethanol content conditions, reduce product irritation, and at the same time take into account the strength of the gel, thus expanding the application range of tamarind polysaccharide.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a method for preparing tamarind polysaccharide gel, comprising the following steps: S1. Add β-galactosidase to the tamarind polysaccharide aqueous solution, perform enzymatic hydrolysis, inactivate the enzyme, precipitate with alcohol, and dry to obtain the enzyme-treated tamarind polysaccharide; wherein, the enzymatic hydrolysis time is 1~2 h; S2. Add the enzyme-treated tamarind polysaccharide to an ethanol-water solution and stir to obtain a mixture; wherein the volume percentage of ethanol in the mixture is less than or equal to 15%; S3. Refrigerate the mixture to obtain tamarind polysaccharide gel.

[0006] Preferably, in step S1: The mass-to-volume ratio of the tamarind polysaccharide aqueous solution is 2%; and / or, The pH value of the tamarind polysaccharide aqueous solution is 5.0; and / or, The mass ratio of the β-galactosidase to the tamarind polysaccharide in the aqueous solution is 0.366:100; and / or, The enzyme activity of the β-galactosidase is 110 U / mg.

[0007] Preferably, in step S1, the enzymatic hydrolysis temperature is 50°C.

[0008] Preferably, in step S1, the enzymatic hydrolysis time is 1 h.

[0009] Preferably, in step S1: The alcohols used for precipitation include anhydrous ethanol; and / or, The drying temperature is 60°C; and / or, After drying, the mixture is pulverized to obtain enzyme-treated tamarind polysaccharide.

[0010] Preferably, in step S2, the mass-to-volume ratio of enzyme-treated tamarind polysaccharide in the mixture is 2%.

[0011] Preferably, in step S2: The stirring temperature is 85℃, and the stirring time is 30 min; and / or, The refrigeration temperature is 4℃, and the refrigeration time is 36 hours.

[0012] Preferably, in step S2, the volume percentage of ethanol in the mixture is 15%.

[0013] Secondly, the present invention provides a tamarind polysaccharide gel prepared by the preparation method described above.

[0014] Thirdly, the present invention provides an application of the tamarind polysaccharide gel described above in solid beverages.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The main raw material of this invention is hydrophilic colloid, which is widely found in the seed endosperm of Tamarindus tamarind (also known as tamarind), a plant of the genus Tamarindus in the Fabaceae family. It has the advantages of wide availability and edibility. The hydrogel made is simple in composition and non-toxic and harmless. (2) The present invention can significantly reduce the amount of ethanol used. Compared with the traditional method (ethanol > 20%), the present invention only requires 15% ethanol to form a stable gel, which reduces the irritation of the product and can improve the strength of the gel. (3) This invention is green and safe, with pure enzymatic modification, no chemical residue, and mild process conditions (50°C). (4) This invention only uses ethanol to induce tamarind polysaccharide to form a gel, without the addition of sugar or other ingredients. First, it can avoid the health controversy caused by added sugar, which is in line with the current development trend of clean label food. Second, the natural antibacterial properties of ethanol can reduce the use of preservatives, and its volatility makes it easy to remove in the future, which can realize the formation of aerogel and the product has low residue. Third, in terms of economic benefits, it reduces the cost of raw materials. (5) This invention can expand the application range of tamarind polysaccharide, and is suitable for food systems with low alcohol content requirements. It can be processed into various forms (granules, suspensions, etc.). Attached Figure Description

[0016] Figure 1 The strength of the tamarind polysaccharide gel provided in Comparative Examples 1-3 of this invention; Figure 2 The strength of the tamarind polysaccharide gels provided in Comparative Example 1, Examples 1-2 and Comparative Example 4 of this invention; Figure 3 The rheological curves of the tamarind polysaccharide gels provided in Comparative Examples 1-3 of this invention are shown below. Figure 4 The rheological curves of the tamarind polysaccharide gels provided in Examples 1-2 and Comparative Example 4 of this invention are shown. Detailed Implementation

[0017] The present invention will now be described in further detail with reference to specific embodiments, so that those skilled in the art can more clearly understand the present invention.

[0018] In a first aspect, the present invention provides a method for preparing tamarind polysaccharide gel, comprising the following steps: S1. Add β-galactosidase to the tamarind polysaccharide aqueous solution, perform enzymatic hydrolysis, inactivate the enzyme, precipitate with alcohol, and dry to obtain the enzyme-treated tamarind polysaccharide; wherein, the enzymatic hydrolysis time is 1~2 h; S2. Add the enzyme-treated tamarind polysaccharide to an ethanol-water solution and stir to obtain a mixture; wherein the volume percentage of ethanol in the mixture is less than or equal to 15%; S3. Refrigerate the mixture to obtain tamarind polysaccharide gel.

[0019] In this invention, the galactose side chain of tamarind polysaccharide molecules is enzymatically cleaved by β-galactosidase, altering the spatial conformation and hydrophilicity of the tamarind polysaccharide molecules. This modification significantly reduces the amount of ethanol used, forming a stable gel under low ethanol content conditions (≤15% (v / v)), reducing product irritation while maintaining gel strength. Furthermore, the pure enzymatic modification method leaves no chemical residues, making it green and safe. It utilizes only ethanol to induce tamarind polysaccharide gel formation without the addition of sugars or other components. This not only avoids health controversies associated with added sugars, aligning with the current trend towards clean label foods, but also reduces raw material costs. Moreover, the natural antibacterial properties of ethanol reduce the use of preservatives, and its volatility facilitates subsequent removal, enabling aerogel formation with low product residue.

[0020] Understandably, the main raw material, tamarind polysaccharide, is a hydrophilic colloid widely found in the seed endosperm of tamarind (also known as tamarind), a plant belonging to the genus Tamarind in the legume family. It has advantages such as wide availability and edibility. The hydrogel produced has a simple composition and is non-toxic and harmless. When the ethanol content is 15% (v / v), it can effectively reduce the irritation of the product. The actual ethanol mass concentration of 20% (v / v) is about 35% higher than that of 15% (v / v) (16.5 / 12.2≈1.35), which is a significant difference.

[0021] Furthermore, in step S1, the mass-to-volume ratio of the tamarind polysaccharide aqueous solution is 2%.

[0022] Furthermore, in step S1, the pH value of the tamarind polysaccharide aqueous solution is 5.0.

[0023] Further, in step S1, the mass ratio of the β-galactosidase to the tamarind polysaccharide in the tamarind polysaccharide aqueous solution is 0.366:100. It can be understood that, based on the mass of the tamarind polysaccharide, the amount of β-galactosidase added is 0.366%.

[0024] Further, in step S1, the enzyme activity of the β-galactosidase is 110 U / mg.

[0025] Furthermore, in step S1, the enzymatic hydrolysis temperature is 50°C. The process conditions for pure enzymatic modification are mild.

[0026] Furthermore, in step S1, the enzymatic hydrolysis time is 1 hour. This more suitable hydrolysis time can improve the strength of the tamarind polysaccharide gel.

[0027] It should be noted that enzyme inactivation can be achieved by boiling in a water bath for 20 minutes.

[0028] Furthermore, in step S1, the alcohol used for precipitation includes anhydrous ethanol.

[0029] Furthermore, in step S1, the drying temperature is 60°C.

[0030] Further, after drying, the material is pulverized to obtain enzyme-treated tamarind polysaccharide. Pulverizing the dried material after drying yields enzyme-treated tamarind polysaccharide, which is beneficial for subsequent gelation.

[0031] Further, in step S2, the mass-to-volume ratio of enzyme-treated tamarind polysaccharide in the mixture is 2% (w / v).

[0032] Furthermore, in step S2, the stirring temperature is 85°C and the stirring time is 30 min.

[0033] Furthermore, in step S2, the refrigeration temperature is 4°C and the refrigeration time is 36 h.

[0034] Furthermore, in step S2, the volume percentage of ethanol in the mixture is 15% (v / v).

[0035] Secondly, the present invention provides a tamarind polysaccharide gel prepared by the preparation method described above.

[0036] Thirdly, this invention provides an application of the tamarind polysaccharide gel described above in solid beverages. The obtained tamarind polysaccharide gel is suitable for food systems requiring low alcohol content (solid beverages such as alcoholic sago and milk tea), and can be processed into various forms (granules, suspensions, etc.), thus expanding the application range of tamarind polysaccharides.

[0037] Example 1 A method for preparing tamarind polysaccharide gel includes the following steps: Step 1: Dissolve 2 g of tamarind polysaccharide in 98 mL of deionized water, stir at room temperature until completely dissolved, and adjust the pH to 5.0; Step 2: Add 7.32 mg of β-galactosidase (enzyme activity 110 U / mg) to the solution and react at 50℃ for 1 h; Step 3: After inactivating the enzyme in a boiling water bath for 20 minutes, add anhydrous ethanol and repeat the purification three times. Dry at 60℃ and then pulverize. Step 4: Dissolve 2 g of enzyme-treated tamarind polysaccharide in 98 mL of 15% ethanol aqueous solution and stir at 85℃ for 30 min until completely dissolved; Step 5: Transfer the mixture into a mold and refrigerate at 4°C for 36 hours to form a gel.

[0038] The strength of the resulting gel increased to 185.64 g, and the gel point temperature was approximately 45°C.

[0039] Example 2 A method for preparing tamarind polysaccharide gel, the steps are the same as in Example 1, except that: in step 2, the enzymatic hydrolysis reaction time is 2 h.

[0040] The strength of the resulting gel increased to 148.48 g, and the gel point temperature was approximately 60°C.

[0041] Comparative Example 1 A method for preparing tamarind polysaccharide gel includes the following steps: Step 1: Dissolve 2 g of tamarind polysaccharide in 98 mL of 15% ethanol aqueous solution and stir at 85℃ for 30 min until completely dissolved; Step 2: Transfer the mixture into a mold and refrigerate at 4°C for 36 hours to form a gel.

[0042] The resulting gel strength was 99.65 g, and the gel temperature was approximately 4°C.

[0043] Comparative Example 2 A method for preparing tamarind polysaccharide gel, the steps are the same as those in Comparative Example 1, except that in step 1, the concentration of the ethanol aqueous solution is 20%.

[0044] The resulting gel strength was 174.24 g, and the gel point temperature was approximately 25°C.

[0045] Comparative Example 3 A method for preparing tamarind polysaccharide gel, the steps are the same as those in Comparative Example 1, except that in step 1, the concentration of the ethanol aqueous solution is 40%.

[0046] Although a gel was formed with a gel strength of 35.38 g, internal stratification occurred.

[0047] Comparative Example 4 A method for preparing tamarind polysaccharide gel, the steps are the same as in Example 1, except that in step 2, the enzymatic hydrolysis reaction time is 4 h.

[0048] The resulting gel had a strength of 81.97 g and was difficult to dissolve.

[0049] Performance Tests and Results The strength of the tamarind polysaccharide gels prepared in Examples 1-2 and Comparative Examples 1-4 were measured respectively. The strength of the tamarind polysaccharide gels in Comparative Examples 1-3 is shown in the figure. Figure 1 (15% ethanol content corresponds to Comparative Example 1, 20% ethanol content corresponds to Comparative Example 2, and 40% ethanol content corresponds to Comparative Example 3). The strength of the tamarind polysaccharide gels of Comparative Example 1, Example 1, Example 2, and Comparative Example 4 is shown in the figure. Figure 2 (0 h corresponds to Example 1, 1 h corresponds to Example 1, 2 h corresponds to Example 2, and 4 h corresponds to Example 4). Figure 1 The changes in the strength of untreated tamarind polysaccharide gels at different ethanol contents (15%, 20%, 40%) are shown. Figure 2 The effect of different enzyme treatment times (0 h, 1 h, 2 h, 4 h) on the gel strength of tamarind polysaccharide at 15% ethanol content was investigated. The rheological curves of the tamarind polysaccharide gels prepared in Examples 1-2 and Comparative Examples 1-4 were measured respectively. The rheological curve of the tamarind polysaccharide gel of Comparative Example 1 is shown in [reference needed]. Figure 2 a. The rheological curve of the tamarind polysaccharide gel in Comparative Example 2 is shown in Figure 1. Figure 2 b, The rheological curve of the tamarind polysaccharide gel in Comparative Example 3 is shown in Figure 3. Figure 2 c, The rheological curve of the tamarind polysaccharide gel in Example 1 is shown in Figure 1. Figure 3 a. The rheological curve of the tamarind polysaccharide gel in Example 2 is shown in Figure 2. Figure 3 b, The rheological curve of the tamarind polysaccharide gel in Example 3 is shown in Figure 3. Figure 3 c. During the cooling process, the intersection of G' (storage modulus) and G'' (loss modulus) is the gel point temperature. When this temperature is reached during the cooling process, the gel begins to form. The higher the gel point temperature, the easier it is for the gel to form. In the figure, "TMG-15%EtOH" means TMG is tamarind polysaccharide, 15%EtOH means ethanol content, and "TMG-15%EtOH-1H" means 1H means enzyme treatment time. The galactose content in the tamarind polysaccharide gels prepared in Examples 1-2, Comparative Example 1, and Comparative Example 4 was measured respectively, and the results are shown in Table 1.

[0050] Table 1. Galactose content of tamarind polysaccharide gel under different enzyme treatment times

[0051] Conclusion: From Figure 1 and Figure 2 It can be seen that enzyme treatment for 1-2 hours can significantly improve the gel strength induced by 15% ethanol content. However, when the enzyme treatment time is extended to 4 hours, the gel strength decreases instead, indicating that excessively long enzyme treatment may have an adverse effect on the polysaccharide structure. Among them, the sample treated with enzyme for 1 hour has the highest gel strength. The gel strength of the sample treated with enzyme with 15% ethanol content for 1 hour (185.64 g) is equivalent to that of the untreated sample with 20% ethanol content (174.24 g). Depend on Figure 3 and Figure 4 It can be seen that increasing the ethanol content can raise the gel point temperature, but too high an ethanol content will make the sample difficult to dissolve (at a 40% ethanol content, as shown in the rheological curve, it needs to be heated to 95℃ to dissolve). As the enzyme treatment time increases, the gel point temperature of the sample increases, but when the enzyme treatment time reaches 4 h, the sample becomes difficult to dissolve. As can be seen from Table 1, the longer the enzyme treatment time, the lower the galactose content; In summary, this invention achieves an optimal balance between the strength (185.64 g) and low irritation (15% ethanol) of tamarind polysaccharide gel by enzymatic treatment with β-galactosidase at 50°C and pH 5.0 for 1-2 hours (1 hour yields the best results) and by combining the treatment with 15% ethanol. The resulting tamarind polysaccharide gel holds promise for use in food systems requiring low alcohol content and can be processed into various forms (granules, etc.).

[0052] Unless otherwise specified, all raw materials used in this invention are existing substances that can be purchased directly from the market.

[0053] The above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing tamarind polysaccharide gel, characterized in that, Includes the following steps: S1. Add β-galactosidase to the tamarind polysaccharide aqueous solution, perform enzymatic hydrolysis, inactivate the enzyme, precipitate with alcohol, and dry to obtain the enzyme-treated tamarind polysaccharide; wherein, the enzymatic hydrolysis time is 1~2 h; S2. Add the enzyme-treated tamarind polysaccharide to an ethanol-water solution and stir to obtain a mixture; wherein the volume percentage of ethanol in the mixture is less than or equal to 15%; S3. Refrigerate the mixture to obtain tamarind polysaccharide gel.

2. The method for preparing tamarind polysaccharide gel according to claim 1, characterized in that, In step S1: The mass-to-volume ratio of the tamarind polysaccharide aqueous solution is 2%; and / or, The pH value of the tamarind polysaccharide aqueous solution is 5.0; and / or, The mass ratio of the β-galactosidase to the tamarind polysaccharide in the aqueous solution is 0.366:100; and / or, The enzyme activity of the β-galactosidase is 110 U / mg.

3. The method for preparing tamarind polysaccharide gel according to claim 1, characterized in that, In step S1, the enzymatic hydrolysis temperature is 50°C.

4. The method for preparing tamarind polysaccharide gel according to claim 1, characterized in that, In step S1, the enzymatic hydrolysis time is 1 h.

5. The method for preparing tamarind polysaccharide gel according to claim 1, characterized in that, In step S1: The alcohols used for precipitation include anhydrous ethanol; and / or, The drying temperature is 60°C; and / or, After drying, the mixture is pulverized to obtain enzyme-treated tamarind polysaccharide.

6. The method for preparing tamarind polysaccharide gel according to claim 1, characterized in that, In step S2, the mass-volume ratio of enzyme-treated tamarind polysaccharide in the mixture is 2%.

7. The method for preparing tamarind polysaccharide gel according to claim 1, characterized in that, In step S2: The stirring temperature is 85℃, and the stirring time is 30 min; and / or, The refrigeration temperature is 4℃, and the refrigeration time is 36 hours.

8. The method for preparing tamarind polysaccharide gel according to claim 1, characterized in that, In step S2, the volume percentage of ethanol in the mixture is 15%.

9. Tamarind polysaccharide gel prepared by the preparation method according to any one of claims 1-8.

10. The application of the tamarind polysaccharide gel according to claim 9 in solid beverages.

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