Preparation method of efficient natural sugar substitute in low-sugar food

Abstract

The invention belongs to the technical field of food chemistry and functional additives, and particularly relates to a high-efficiency natural sugar substitute in low-sugar food and a preparation method of the high-efficiency natural sugar substitute. The substitute is prepared from modified gallic acid and 2-hydroxy-1, 3-propane diketone as main raw materials, and Arabic gum, maltodextrin, sodium citrate, xanthan gum and a base catalyst as auxiliary materials. The modified gallic acid is prepared by performing catalytic glycosylation on gallic acid through glucosyltransferase and performing graft modification on the glycosylated gallic acid and L-lysine, and a glycoside-amide bifunctional structure is formed. In the preparation process, a stable composite system is obtained through condensation, crosslinking and spray drying. Through synergistic reaction of enzymatic glycosylation and amino acid grafting, the product is remarkably improved in sweet softness, thermal stability, solubility and oxidation resistance, can be widely applied to low-sugar foods, beverages and functional health-care products, and has the advantages of being natural, safe and stable in flavor.

Description

Technical Field

[0001] This invention belongs to the field of food chemistry and natural product modification technology, specifically relating to a highly efficient natural sugar substitute for low-sugar foods and its preparation method. Background Technology

[0002] The demand for low-sugar foods continues to grow in the beverage, dairy, and baked goods sectors, making sugar substitutes important ingredients for controlling calorie intake and glycemic response. Commonly used sugar substitutes include erythritol, steviol glycosides, sucralose, and allulose. Erythritol has a sweetness of about 70% that of sucrose, dissolves with significant endothermic reaction, and has a cool taste; steviol glycosides are derived from plant extracts, are highly sweet, but have a bitter and metallic taste; sucralose is a synthetic chlorosucrose that is easily decomposed under heating and acidic conditions; allulose is a rare monosaccharide that is prone to isomerization during processing, leading to a decrease in sweetness and a darkening of color.

[0003] Synthetic sweeteners perform well in terms of sensory consistency, but suffer from poor thermal stability and a high risk of chemical residues. Natural sweeteners are safe in origin, but their flavors are complex and easily destabilized by pH and temperature. Some studies have attempted to use polyphenolic compounds, amino acid derivatives, or glycosylation products as natural sweetener modifiers, but these substances often have a bitter taste, insufficient solubility, poor sweetness persistence, and are difficult to stabilize in complex food systems.

[0004] The requirements for sugar substitute systems in low-sugar foods include high sweetness, pure taste, strong thermal stability, good antioxidant properties, and strong compatibility with food matrices. Current technology lacks a natural complex sugar substitute that can enhance the sweetness while maintaining a smooth flavor and functional stability. Summary of the Invention

[0005] To overcome the technical challenges of insufficient sweetness, poor thermal stability, unbalanced flavor, and lack of antioxidant function in existing sugar substitutes for low-sugar foods, this invention aims to provide a highly efficient natural sugar substitute for low-sugar foods and its preparation method. This invention uses modified gallic acid and 2-hydroxy-1,3-propanedione as main raw materials. Gallic acid undergoes glycosylation catalyzed by glucosyltransferase and is grafted with L-lysine to form a natural phenolic derivative with hydrophilic and neutral flavor characteristics. This derivative then undergoes a condensation reaction with small-molecule organic compounds containing carbonyl and hydroxyl functional groups to construct a composite system with a hydroxy-carbonyl balanced structure. By compounding with stabilizing agents such as gum arabic, maltodextrin, sodium citrate, and xanthan gum, a powdered natural sugar substitute is obtained through mixing, condensation, and spray drying. The natural sugar substitute obtained by this invention has a sweetness 1.8 to 2.3 times that of sucrose, a pure and mellow sweetness, is resistant to high temperatures and acidic environments, and possesses strong antioxidant and preservation properties. It is suitable for low-sugar formulation systems in beverages, dairy products, and baked goods.

[0006] The objective of this invention can be achieved through the following technical solutions: A highly efficient natural sugar substitute for low-sugar foods comprises the following raw materials in parts by weight: 10-20 parts modified gallic acid; 10-30 parts 2-hydroxy-1,3-propanedione; 5-10 parts gum arabic; 3-8 parts maltodextrin; 1-3 parts sodium citrate; 0.2-0.6 parts xanthan gum; and 0.1-0.5 parts alkaline catalyst. The modified gallic acid is obtained by glycosylation of gallic acid catalyzed by glucosyltransferase and grafting with L-lysine. The 2-hydroxy-1,3-propanedione is a simple small-molecule organic compound containing carbonyl and hydroxyl functional groups.

[0007] Optionally, the modified gallic acid comprises the following raw materials in parts by weight: 10-20 parts gallic acid; 0.5-1 part glucosyltransferase; 1-3 parts L-lysine; and 50-100 parts ethanol-water mixed solvent.

[0008] Optionally, the preparation method of modified gallic acid includes the following steps: (1) Add gallic acid to an ethanol-water mixture and stir to dissolve it to obtain a solution; (2) Add glucose transferase to the solution to carry out glycosylation reaction; (3) Add L-lysine to the reaction system to carry out the grafting reaction and obtain the modified reaction solution; (4) The modified reaction solution is purified and dried to obtain the modified gallic acid product.

[0009] Optionally, the reaction conditions in step (1) are stirring at room temperature for 10 to 20 minutes.

[0010] Optionally, the glycosylation reaction conditions in step (2) are 40-50°C for 1-2 hours.

[0011] Optionally, the grafting reaction conditions in step (3) are 45-55°C for 1-2 hours.

[0012] Optionally, the reaction conditions in step (4) are as follows: 40~ Dry at 50℃ for 8–12 hours.

[0013] Optionally, the alkaline catalyst is a mixture of sodium hydroxide and sodium carbonate in a mass ratio of 1:1 to 2.

[0014] Optionally, a method for preparing a highly efficient natural sugar substitute in low-sugar foods includes the following steps: S1, Modified gallic acid is mixed with 2-hydroxy-1,3-propanedione and stirred until homogeneous to form a reaction solution; S2, add an alkaline catalyst to the reaction solution to carry out a condensation reaction and obtain a composite reaction solution; S3, add gum arabic, maltodextrin, sodium citrate and xanthan gum to the composite reaction solution in sequence, and stir evenly to form a stable system; S4 involves spray drying the stable system to obtain a highly efficient natural sugar substitute product for low-sugar foods.

[0015] Optionally, the reaction conditions for step S1 are stirring at room temperature for 10 to 20 minutes; the reaction conditions for step S2 are reacting at 45 to 60°C for 1 to 2 hours; the reaction conditions for step S3 are stirring at room temperature for 20 to 30 minutes; and the reaction conditions for step S4 are spray drying at an inlet air temperature of 140 to 160°C.

[0016] The beneficial effects of this invention are: This invention utilizes a dual modification process of enzymatic glycosylation and amino acid grafting to form an ordered glycosylation-amino acid hydrophilic layer structure around the aromatic ring of gallic acid molecules. This significantly reduces the exposure of phenolic hydroxyl groups between molecules and results in a more uniform charge distribution, effectively weakening bitterness and astringency, thus achieving flavor neutralization. Upon condensation with 2-hydroxy-1,3-propanedione, a stable hydroxy-carbonyl equilibrium structure is formed, constructing a microscale hydrogen bond network within the system. This enhances intermolecular interactions, resulting in a more uniform sweetness release process and a significantly reduced sweetness delay effect.

[0017] The presence of the hydroxyl-carbonyl network enhances the molecular structural stability of the composite system under heating and low pH conditions, inhibits the self-polymerization reaction of reduced carbonyl groups, and prevents the system from darkening in color and deteriorating in flavor. This structural feature provides lower-sugar foods with more durable flavor stability and processing adaptability. Attached Figure Description

[0018] The invention will now be further described with reference to the accompanying drawings.

[0019] Figure 1 The infrared spectra of gallic acid and modified gallic acid are compared. Figure 2 Line graph comparing the sweetness retention rate test results of samples with different ratios. Detailed Implementation

[0020] The present invention will be further described below with reference to specific embodiments. However, the present invention is not limited to the following embodiments. Equivalent adjustments made without departing from the spirit and essence of the present invention should also be considered to fall within the protection scope of the present invention.

[0021] Example 1 The purpose of this embodiment is to verify the effect of modified gallic acid on the formation and basic stability of the sweet flavor structure under low ratio conditions, and to provide a basis for determining the minimum effective content.

[0022] S1, weigh 10 parts gallic acid and add it to 50 parts ethanol-water mixed solvent, stir to dissolve for 10 minutes to obtain a clear solution. Add 0.5 parts glucosyltransferase and react at 40℃ for 1 hour; then add 1 part L-lysine and maintain the reaction at 45℃ for 1 hour. After the reaction is completed, concentrate under reduced pressure and then... Modified gallic acid powder was obtained by freeze-drying at 40℃ for 10 hours. S2, 10 parts of modified gallic acid and 10 parts of 2-hydroxy-1,3-propanedione are mixed evenly to form a reaction solution, 0.1 parts of alkaline catalyst are added, and the reaction is carried out at 45°C for 1 hour to obtain a composite reaction solution; S3. Add 5 parts gum arabic, 3 parts maltodextrin, 1 part sodium citrate, and 0.2 parts xanthan gum sequentially to the composite reaction solution, and stir at room temperature for 20 minutes to form a homogeneous system. Dry the resulting system in a spray drying tower at an inlet air temperature of 140℃ to obtain a light yellow powdery natural sugar substitute.

[0023] Example 2 The purpose of this embodiment is to investigate the balance and sweetness of the condensation reaction between modified gallic acid and small molecule carbonyl compounds under moderate ratio conditions, and to provide experimental basis for the optimal ratio.

[0024] S1, 15 parts of gallic acid were weighed and added to 75 parts of an ethanol-water mixture, stirred and dissolved for 15 minutes. 0.8 parts of glucosyltransferase were added, and the mixture was reacted at 45°C for 1.5 hours. Subsequently, 2 parts of L-lysine were added, and the mixture was reacted at 50°C for 1.5 hours. After the reaction was completed, the mixture was concentrated under reduced pressure and... Modified gallic acid powder was obtained by freeze-drying at 45°C for 10 hours. Figure 1 The results showed that the molecular structure of gallic acid changed significantly before and after modification. The unmodified sample at 3400 cm⁻¹... -1 A broad and strong peak appears at approximately 3300 cm⁻¹, indicating O–H stretching vibration; after modification, this peak broadens and reaches approximately 3300 cm⁻¹. -1 A new N–H absorption peak appeared at 1700 cm⁻¹, indicating that the lysine grafting successfully introduced an amino group. The original sample showed an absorption peak at 1700 cm⁻¹. -1 The C=O stretching peak at this point weakens and shifts towards 1650 cm⁻¹. -1 Move, simultaneously 1540cm -1 The appearance of a new amide band at this location indicates that an amidation reaction has occurred. The modified sample showed this reaction at 1150–1080 cm⁻¹. -1 Enhanced absorption in the region and the appearance of 900cm -1 The β-glycoside peak confirmed the formation of C–O–C bonds through glycosylation. Overall, this indicates that the modified gallic acid has formed a glycoside-amide bistructure, verifying the "synergistic modification mechanism of enzymatic glycosylation and amino acid grafting"; S2, 15 parts of modified gallic acid and 20 parts of 2-hydroxy-1,3-propanedione were mixed, stirred evenly, and then 0.3 parts of alkaline catalyst were added. The mixture was reacted at 50°C for 1.5 hours to obtain a composite reaction solution. S3. Add 7 parts gum arabic, 5 parts maltodextrin, 2 parts sodium citrate, and 0.4 parts xanthan gum sequentially to the composite reaction solution, and stir at room temperature for 25 minutes to form a stable system. Spray dry the system at an inlet air temperature of 150℃ to obtain a pale yellow powder with a mild sweet taste.

[0025] Example 3 The purpose of this embodiment is to study the formation characteristics of the hydroxy-carbonyl structural network in the system under high ratio conditions and its effect on flavor stability.

[0026] S1, weigh 20 parts gallic acid and add it to 100 parts ethanol-water mixed solvent, stirring and dissolving for 20 minutes. Add 1 part glucosyltransferase and react at 50℃ for 2 hours; then add 3 parts L-lysine and react at 55℃ for 2 hours. The reaction solution is concentrated under reduced pressure and then... Modified gallic acid powder was obtained by freeze-drying at 50°C for 12 hours. S2, 20 parts of modified gallic acid and 30 parts of 2-hydroxy-1,3-propanedione are mixed to form a reaction solution, 0.5 parts of alkaline catalyst are added, and the mixture is reacted at 60°C for 2 hours to generate a composite reaction solution; S3. Add 10 parts gum arabic, 8 parts maltodextrin, 3 parts sodium citrate, and 0.6 parts xanthan gum sequentially to the composite reaction solution, stir at room temperature for 30 minutes to obtain a homogeneous system. Spray dry at an inlet air temperature of 160℃ to obtain a light brown powdery natural sugar substitute with a mellow sweetness.

[0027] Comparative Example 1 The purpose of this comparative study is to investigate the effect of glycosylation modification alone on sweetness and system stability under conditions where amino acid grafting is lacking.

[0028] S1, weigh 15 parts gallic acid and add it to 75 parts ethanol-water mixed solvent, stirring to dissolve for 15 minutes. Add 0.8 parts glucosyltransferase and react at 45℃ for 1.5 hours. Do not add L-lysine. After the reaction is complete, concentrate under reduced pressure and... Freeze-dry at 45°C for 10 hours to obtain glycosylated modified gallic acid powder; S2, 15 parts of modified gallic acid and 20 parts of 2-hydroxy-1,3-propanedione were mixed, stirred evenly, and then 0.3 parts of alkaline catalyst were added. The mixture was reacted at 50°C for 1.5 hours to obtain a composite reaction solution. S3. Add 7 parts gum arabic, 5 parts maltodextrin, 2 parts sodium citrate, and 0.4 parts xanthan gum sequentially to the composite reaction solution, and stir at room temperature for 25 minutes to form a stable system. Spray dry at an inlet air temperature of 150℃ to obtain the powder of Comparative Example 1.

[0029] Comparative Example 2 The purpose of this comparative study is to investigate the effect of amino acid grafting alone on sweetness and flavor harmony under conditions lacking glycosylation.

[0030] S1, weigh 15 parts gallic acid and add it to 75 parts ethanol-water mixed solvent, stirring to dissolve for 15 minutes. Without adding glucosyltransferase, directly add 2 parts L-lysine and react at 50℃ for 1.5 hours. After the reaction, concentrate under reduced pressure and... The modified gallic acid powder was obtained by freeze-drying at 45°C for 10 hours.

[0031] S2, 15 parts of modified gallic acid and 20 parts of 2-hydroxy-1,3-propanedione were mixed, stirred evenly, and then 0.3 parts of alkaline catalyst were added. The mixture was reacted at 50°C for 1.5 hours to obtain a composite reaction solution.

[0032] S3. Add 7 parts gum arabic, 5 parts maltodextrin, 2 parts sodium citrate, and 0.4 parts xanthan gum sequentially to the composite reaction solution, and stir at room temperature for 25 minutes to form a stable system. Spray dry at an inlet air temperature of 150℃ to obtain the powder of Comparative Example 2.

[0033] Comparative Example 3 The purpose of this comparative example is to investigate the changes in the condensation reaction and sweetness levels of the system in the absence of 2-hydroxy-1,3-propanedione.

[0034] S1, 15 parts of gallic acid were weighed and added to 75 parts of an ethanol-water mixture, stirred and dissolved for 15 minutes. 0.8 parts of glucosyltransferase were added, and the mixture was reacted at 45°C for 1.5 hours. Subsequently, 2 parts of L-lysine were added, and the mixture was reacted at 50°C for 1.5 hours. After the reaction was completed, the mixture was concentrated under reduced pressure and... Modified gallic acid powder was obtained by freeze-drying at 45°C for 10 hours. S2, 15 parts of modified gallic acid were evenly dispersed in deionized water without adding 2-hydroxy-1,3-propanedione, and 0.3 parts of alkaline catalyst were added. The mixture was reacted at 50°C for 1.5 hours to obtain the reaction solution. S3, add 7 parts gum arabic, 5 parts maltodextrin, 2 parts sodium citrate, and 0.4 parts xanthan gum sequentially to the reaction solution, and stir at room temperature for 25 minutes to form a stable system. Spray dry at an inlet air temperature of 150℃ to obtain the powder of Comparative Example 3.

[0035] Performance testing 1. Determination of sweetness intensity and isosweetness coefficient To evaluate the sweetness intensity of the samples, a sucrose solution was selected as a standard reference, and a sample solution with a mass fraction of 0.50% was prepared. The isosweetness was assessed using a two-way forced selection method and a three-point comparison method, with 20 trained evaluators conducting blind evaluations under constant temperature conditions. By comparing the isosweetness of the sucrose solution and the sample solution, the relative sweetness intensity of each sample was determined, and the isosweetness coefficient was calculated. The test results are used to reflect the differences in sweetness perception among different formulations.

[0036] 2. Evaluation of sweetness persistence and aftertaste To analyze the sweetness release process and aftertaste characteristics, a 0.50% (w / w) sample solution was prepared. The changes in sweetness intensity and bitterness within the range of 0 to 120 seconds were measured using time-intensity analysis. The time of peak sweetness, duration of sweetness, intensity of bitterness, and duration of aftertaste were recorded. Based on the time-intensity curves, the onset rate, peak intensity, and aftertaste characteristics of sweetness were evaluated to determine the influence of different structural systems on the sweetness balance.

[0037] 3. Determination of thermal stability and pH stability To investigate the structural stability of the samples during processing, the sample solutions were adjusted to pH 3.0 and pH 7.0, and then heated in a 90℃ water bath for 30 minutes before cooling to room temperature. The retention of sweetness and color changes before and after heating were tested, and the absorbance change at 420 nm was measured spectrophotometrically. The sweetness retention rate and color stability of each sample under different pH and high temperature conditions were compared to evaluate their structural resistance to degradation.

[0038] 4. Determination of solubility and clarity To compare the dissolution rate and system homogeneity of the samples, the samples were added to a thermostatic magnetic stirrer, and the time required for complete dissolution was recorded at 300 rpm. After the solution clarified, the absorbance and turbidity of the supernatant were measured at 600 nm. Based on the changes in dissolution time and clarity, the water solubility and system dispersion homogeneity of the samples were analyzed, and their suitability for beverage and food applications was evaluated.

[0039] 5. Determination of synergistic effects of antioxidant and preservation properties To verify the antioxidant capacity of the samples and its impact on the preservation performance of the system, a 2,2-diphenyl-1-picrylhydrazyl free radical scavenging test and a vitamin C accelerated storage test were conducted. In the 2,2-diphenyl-1-picrylhydrazyl free radical test, the absorbance change was measured after the sample solution reacted with a 2,2-diphenyl-1-picrylhydrazyl free radical ethanol solution to characterize the free radical scavenging capacity. In the vitamin C storage test, the samples were added to a buffer solution system containing vitamin C and stored at 40℃ in the dark for 7 and 14 days. The residual amount of vitamin C was measured to reflect the preservation effect. The antioxidant rate and vitamin C retention rate of different samples were compared to determine the synergistic contribution of the modified structure to the preservation performance.

[0040] Table 1. Results of Sensory and Sweetness Performance Tests Table 2 Results of stability and antioxidant performance tests As shown in Table 1, Examples 1-3 are significantly superior to the comparative examples in terms of sweetness intensity and flavor characteristics. Example 2 has a sweetness intensity similar to sucrose, with the longest duration of sweetness and the lowest aftertaste of bitterness, indicating that the molecular structure formed under medium ratio conditions is the most balanced, resulting in a smoother sweetness release and a more rounded taste. Example 3, under high ratio conditions, has a slightly lower sweetness intensity than Example 2, but better sweetness persistence; Example 1, under low ratio conditions, has a weaker sweetness intensity but is still significantly higher than the comparative examples. Comparative Examples 1 and 2, lacking a dual-modified structure, exhibit uneven sweetness release and a pronounced bitterness; Comparative Example 3, due to the absence of small-molecule carbonyl components, has the worst overall flavor harmony.

[0041] As shown in Table 2, Examples 1-3 outperformed the comparative examples in terms of sweetness retention, solubility, and antioxidant properties. Example 2 exhibited the highest sweetness retention, shortest solubility, and best clarity, while also demonstrating significantly enhanced antioxidant capacity. Its vitamin C retention remained high even after 7 and 14 days of storage, indicating a stable structural structure and outstanding antioxidant activity. Example 3, with its increased structural density at a higher formulation ratio, showed slightly higher sweetness retention and antioxidant capacity than Example 2, but a slight decrease in flavor smoothness. In contrast, the comparative samples showed significant sweetness decay and lower antioxidant capacity under heating and storage conditions. Comparative Example 3, lacking carbonyl components, failed to form a hydrogen bond network, making the system prone to turbidity and oxidative browning.

[0042] Comprehensive analysis results show that all three sets of examples exhibit superior sweetness characteristics and system stability compared to the comparative examples. Among them, Example 2 achieves the optimal balance in terms of sweetness sensory experience, dissolution rate, and antioxidant performance. These results fully validate the effectiveness of the "enzymatic glycosylation-amino acid grafting-carbonyl synergistic" composite modification strategy, demonstrating that the structural design of this invention not only improves sweetness release and flavor balance but also significantly enhances the antioxidant and processing stability of the sugar substitute system.

Claims

1. A highly effective natural sugar substitute in a low sugar food, characterized by, The modified gallic acid, 2-hydroxy-1,3-propanedione, arabic gum, malt dextrin, sodium citrate, xanthan gum and alkali catalyst are mixed to form a reaction solution; the alkali catalyst is added to the reaction solution to perform a condensation reaction, thereby obtaining a composite reaction solution; the arabic gum, malt dextrin, sodium citrate and xanthan gum are sequentially added to the composite reaction solution to form a stable system; and the stable system is subjected to spray drying to obtain the high-efficiency natural sugar substitute product in low-sugar food.

2. The highly effective natural sugar substitute in low sugar food according to claim 1, characterized in that, The modified gallic acid comprises the following raw materials in parts by weight: gallic acid 10-20 parts, glucose transferase 0.5-1 part, L-lysine 1-3 parts and ethanol-water mixed solvent 50-100 parts.

3. The highly effective natural sugar substitute in a low-sugar food according to any one of claims 1 or 2, characterized in that, The preparation method of the modified gallic acid comprises the following steps: (1) the gallic acid is added to an ethanol-water mixed solution to be stirred and dissolved to obtain a solution; (2) the glucose transferase is added to the solution to perform a glycosylation reaction; (3) the L-lysine is added to the reaction system to perform a grafting reaction, thereby obtaining a modified reaction solution; (4) the modified reaction solution is purified and dried to obtain the modified gallic acid product.

4. The highly effective natural sugar substitute in low-sugar food according to claim 3, characterized in that, The reaction condition of step (1) is stirring at room temperature for 10-20 minutes.

5. The highly effective natural sugar substitute in low sugar food according to claim 3, characterized in that, The glycosylation reaction condition of step (2) is a reaction at 40-50°C for 1-2 hours.

6. The highly effective natural sugar substitute in low sugar food according to claim 3, characterized in that, The grafting reaction condition of step (3) is a reaction at 45-55°C for 1-2 hours.

7. The highly effective natural sugar substitute in low sugar food according to claim 3, characterized in that, The reaction conditions of the step (4) are 40 to 50 50°C for 8 to 12 hours.

8. The highly effective natural sugar substitute in low sugar food according to claim 1, characterized in that, The alkali catalyst is a mixture of sodium hydroxide and sodium carbonate in a mass ratio of 1:1-2.

9. A method for producing a high-performance natural sugar substitute in a low-sugar food product, the high-performance natural sugar substitute being as claimed in any one of claims 1 to 8, characterized by, The method comprises the following steps: S1, the modified gallic acid and 2-hydroxy-1,3-propanedione are mixed to be stirred uniformly to form a reaction solution; S2, the alkali catalyst is added to the reaction solution to perform a condensation reaction, thereby obtaining a composite reaction solution; S3, the arabic gum, malt dextrin, sodium citrate and xanthan gum are sequentially added to the composite reaction solution to be stirred uniformly to form a stable system; S4, the stable system is subjected to spray drying to obtain the high-efficiency natural sugar substitute product in low-sugar food.

10. The method for preparing a highly efficient natural sugar substitute in a low-sugar food according to claim 9, characterized in that, The reaction condition of step S1 is stirring at room temperature for 10-20 minutes; the reaction condition of step S2 is a reaction at 45-60°C for 1-2 hours; the reaction condition of step S3 is stirring at room temperature for 20-30 minutes; and the reaction condition of step S4 is spray drying at an inlet air temperature of 140-160°C.

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