Low-sugar high-milk-fat-ratio chocolate and preparation method thereof

Abstract

The invention discloses low-sugar high-butter-fat-ratio chocolate and a preparation method thereof, and aims to solve the problems of poor emulsification stability and rough taste of the existing product. The method comprises the following steps: performing enzymolysis on lactoferrin, and performing transglutaminase cross-linking on lactoferrin and whey protein to prepare a modified compound protein emulsifier; and carrying out segmented ultrasonic emulsification on the milk fat, combining with a brown low-sugar sweetening agent, and carrying out temperature regulation and molding to obtain the product. Through the synergistic effect of the modified protein and the ultrasonic process, the milk fat precipitation rate is reduced to 2-5%, the taste smoothness is improved, the dosage of the emulsifier is reduced by 30-45%, the process energy consumption is reduced by 35-45%, and the product has low-sugar and high-milk fat taste and the lactoferrin nutrition function and has wide market application prospects.

Description

Technical Field

[0001] This invention relates to the field of food processing, specifically to a low-sugar, high-fat chocolate and its preparation method. Background Technology

[0002] Existing low-sugar chocolate products often suffer from poor emulsification stability and a rough texture, especially in high-fat-ratio chocolates where milk fat tends to separate, affecting the product's appearance and taste. Furthermore, the sweeteners used in conventional low-sugar chocolates often introduce sugar substitute crystals and a grainy texture, reducing the smoothness of the mouthfeel. While the traditional emulsifier soy lecithin can improve emulsification, its stability in high-fat systems is insufficient, and it requires a relatively high addition amount. To address these issues, a preparation method based on modified composite protein emulsifiers and ultrasonic emulsification technology was developed. Through the synergistic effect of precise modification and directional processing, emulsification stability and mouthfeel smoothness are significantly improved, meeting the dual requirements of low-sugar, high-fat chocolate for both emulsification performance and mouthfeel. Summary of the Invention

[0003] To address the aforementioned problems, this invention proposes a low-sugar, high-fat chocolate and its preparation method. This chocolate utilizes a modified composite protein emulsifier combined with ultrasonic emulsification, which not only effectively improves emulsification stability and reduces milk fat precipitation but also significantly enhances its smoothness. By optimizing the cross-linking structure of lactoferrin and whey protein and adjusting the sweetener ratio, the chocolate of this invention maintains excellent taste and stability while being low in sugar and high in milk fat, making it suitable for low-sugar and healthy diets.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: A low-sugar, high-fat chocolate and its preparation method, wherein the chocolate is prepared from the following raw materials in parts by weight: 20-25 parts cocoa liquor, 10-15 parts cocoa butter, 15-20 parts milk fat, 1.5-2.0 parts modified complex protein emulsifier, 12-15 parts low-sugar sweetener, 5-8 parts milk powder, 0.1-0.3 parts lecithin, and 0.5-1.5 parts natural antioxidant.

[0005] Preferably, the preparation method of the low-sugar, high-fat-ratio chocolate includes the following specific steps: S1. After hydrolyzing lactoferrin, mix it with whey protein, add transglutaminase to carry out cross-linking reaction, and obtain modified composite protein emulsifier. S2. Mix the modified composite protein emulsifier with milk fat, and perform low-frequency coarse emulsification at 15~25 kHz and high-frequency fine emulsification at 35~45 kHz in sequence. S3. Add low-sugar sweeteners and antioxidants to the emulsion system, and then grind, temper, and shape to obtain low-sugar, high-fat chocolate.

[0006] Preferably, the lactoferrin is selected from one or more of trypsin, papain, and pepsin, and the amount of enzyme added is 0.5-1% of the lactoferrin protein mass. The enzymatic hydrolysis pH is 7.0-7.5, the temperature is 35-40℃, the reaction time is 15-20 min, and the molecular weight of the lactoferrin hydrolysate peptide after enzymatic hydrolysis is 300-1000 Da.

[0007] Preferably, the mass ratio of lactoferrin to whey protein is 1:2 to 1:3, the transglutaminase activity is 80 to 120 U / g, the cross-linking reaction temperature is 40 to 50°C, and the reaction time is 60 to 90 min.

[0008] Preferably, after the crosslinking reaction is completed, the modified composite protein emulsifier is spray-dried at an inlet air temperature of 180-200°C and an outlet air temperature of 80-90°C to obtain modified composite protein powder with a particle size of 50-80 μm and a moisture content of 1-3%.

[0009] Preferably, the low-sugar sweetener is one or more of erythritol, steviol glycosides and xylitol, the mass ratio of the sweetener is 2:1 to 4:1, the total amount added accounts for 10 to 15% of the total mass of chocolate, and the total sugar content of chocolate is 2 to 3 g / 100 g.

[0010] Preferably, in step S3, the particle size of the ground material is 10~15 μm, and the β-crystal content is 90~95% during the temperature adjustment process.

[0011] Preferably, the natural antioxidant is a compound of rosemary extract and vitamin E, with a mass ratio of 1:1 to 1:3, and the oxidative acid value of the chocolate is 0.5 to 1.0 mg / g after being stored at 25°C for 6 months.

[0012] Preferably, the amount of modified composite protein emulsifier added to the chocolate is 1.5~2.0%, the milk fat separation rate is 1~2%, and the protein content is 5~10%.

[0013] The beneficial effects of this invention are: The low-sugar, high-fat-ratio chocolate prepared by this invention exhibits excellent emulsification stability and smooth texture, with a milk fat separation rate of 1-2%, significantly improving the overall quality of the chocolate. Simultaneously, this chocolate provides a good substitute for low-sugar sweeteners, with a total sugar content of 2-3 g / 100g, meeting the requirements of a low-sugar diet. It also lacks sugar substitute crystals or a grainy texture, offering a delicate and smooth mouthfeel. Furthermore, the synergistic effect of modified composite protein emulsifiers and ultrasonic emulsification technology effectively reduces the amount of emulsifier used, lowering production costs. In addition, the lactoferrin in the chocolate provides additional immune support functions, enhancing its nutritional value. Attached Figure Description

[0014] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof.

[0015] Figure 1 This is a comparison chart of the fat extraction rate and oxidative acid value of various samples in this invention; Figure 2 This is a bar chart comparing the total sugar content of various samples in this invention. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0017] Example 1: This embodiment 1 describes a low-sugar, high-fat chocolate, prepared from the following raw materials in parts by weight: 22 parts cocoa liquor, 12 parts cocoa butter, 18 parts milk fat, modified complex protein emulsifier: lactoferrin 0.51 parts, whey protein 1.29 parts, low sugar sweetener: erythritol / stevioside = 3:1 14 parts, milk powder 6 parts, lecithin 0.2 parts, natural antioxidant: rosemary extract / vitamin E = 1:2 1.0 parts.

[0018] The preparation method of low-sugar, high-fat chocolate in this embodiment includes the following specific steps: S1. Dissolve lactoferrin in 100 mL of deionized water, add trypsin with an enzyme activity of 250 U / mg, the amount added is 0.8% of the lactoferrin mass, adjust the pH to 7.2, control the temperature at 38℃, and carry out the enzymatic hydrolysis reaction for 18 min to obtain enzymatically hydrolyzed lactoferrin peptides with a molecular weight of 300~1000 Da. S2. Mix enzymatically hydrolyzed lactoferrin peptides with whey protein at a mass ratio of 1:2.5, add transglutaminase with an activity of 100 U / g, and add 0.8% of the total mass of the protein mixture. Crosslink the mixture at 45°C for 75 min to obtain a modified composite protein emulsifier. S3. Weigh the milk fat and modified composite protein emulsifier, add them to the mixing container, and sonicate at low frequency for 5 minutes at a power of 200 W and a frequency of 20 kHz. Then switch to high frequency sonication at a power of 150 W and a frequency of 40 kHz for 3 minutes to complete the emulsification. S4. Add cocoa liquor, cocoa butter, milk powder, lecithin, low-sugar sweetener, and natural antioxidant to the emulsification system. After mixing evenly, grind to a particle size of 12 μm. After molding, cool to room temperature to obtain low-sugar, high-fat-ratio chocolate.

[0019] Example 2: This embodiment 2 presents a low-sugar, high-fat-ratio chocolate, prepared from the following raw materials in parts by weight: 22 parts cocoa liquor, 12 parts cocoa butter, 20 parts milk fat, modified complex protein emulsifier: lactoferrin 0.57 parts, whey protein 1.43 parts, low sugar sweetener: erythritol / stevioside = 3:1 14 parts, milk powder 6 parts, lecithin 0.2 parts, natural antioxidant: rosemary extract / vitamin E = 1:2 1.0 parts.

[0020] The preparation method of the low-sugar, high-fat chocolate in this embodiment is the same as that in Example 1.

[0021] Example 3: This embodiment 3 presents a low-sugar, high-fat-ratio chocolate, prepared from the following raw materials in parts by weight: 22 parts cocoa liquor, 12 parts cocoa butter, 15 parts milk fat, modified complex protein emulsifier: lactoferrin 0.43 parts, whey protein 1.07 parts, low sugar sweetener: erythritol / stevioside = 3:1 14 parts, milk powder 6 parts, lecithin 0.2 parts, natural antioxidant: rosemary extract / vitamin E = 1:2 1.0 parts.

[0022] The preparation method of the low-sugar, high-fat chocolate in this embodiment is the same as that in Example 1.

[0023] Comparative Example 1: To investigate the effect of non-enzymatic hydrolysis on chocolate, chocolate was prepared from the following parts by weight of raw materials: 22 parts cocoa liquor, 12 parts cocoa butter, 15 parts milk fat, modified complex protein emulsifier: lactoferrin 0.51 parts, whey protein 1.29 parts, low sugar sweetener: erythritol / stevioside = 3:1 14 parts, milk powder 6 parts, lecithin 0.2 parts, natural antioxidant: rosemary extract / vitamin E = 1:2 1.0 parts.

[0024] The specific preparation steps for the chocolate in this comparative example are as follows: S1. Lactoferrin and whey protein were mixed at a mass ratio of 1:2.5. Transglutaminase with an activity of 100 U / g was added at a mass of 0.8% of the total mass of the protein mixture. The mixture was subjected to a cross-linking reaction at 45°C for 75 min to obtain a modified composite protein emulsifier. S2. Weigh the milk fat and modified composite protein emulsifier, add them to the mixing container, and sonicate at low frequency for 5 minutes at a power of 200 W and a frequency of 20 kHz. Then switch to high frequency sonication at a power of 150 W and a frequency of 40 kHz for 3 minutes to complete the emulsification. S3. Add cocoa liquor, cocoa butter, milk powder, lecithin, low-sugar sweetener, and natural antioxidant to the emulsification system. After mixing evenly, grind to a particle size of 12 μm. After molding, cool to room temperature to obtain chocolate.

[0025] Comparative Example 2: To investigate the effect of non-crosslinking treatment on chocolate, the chocolate was prepared from the following parts by weight of raw materials: 22 parts cocoa liquor, 12 parts cocoa butter, 15 parts milk fat, modified complex protein emulsifier: lactoferrin 0.51 parts, whey protein 1.29 parts, low sugar sweetener: erythritol / stevioside = 3:1 14 parts, milk powder 6 parts, lecithin 0.2 parts, natural antioxidant: rosemary extract / vitamin E = 1:2 1.0 parts.

[0026] The preparation method of the low-sugar, high-fat chocolate in this comparative example includes the following specific steps: S1. Dissolve lactoferrin in 100 mL of deionized water, add trypsin with an enzyme activity of 250 U / mg, the amount added is 0.8% of the lactoferrin mass, adjust the pH to 7.2, control the temperature at 38℃, and carry out the enzymatic hydrolysis reaction for 18 min to obtain enzymatically hydrolyzed lactoferrin peptides with a molecular weight of 300~1000 Da. S2. Mix enzymatically hydrolyzed lactoferrin peptides and whey protein at a mass ratio of 1:2.5, and stir at 45°C for 75 min to obtain a composite protein emulsifier. S3. Weigh the milk fat and modified composite protein emulsifier, add them to the mixing container, and sonicate at low frequency for 5 minutes at a power of 200 W and a frequency of 20 kHz. Then switch to high frequency sonication at a power of 150 W and a frequency of 40 kHz for 3 minutes to complete the emulsification. S4. Add cocoa liquor, cocoa butter, milk powder, lecithin, low-sugar sweetener, and natural antioxidant to the emulsification system. After mixing evenly, grind to a particle size of 12 μm. After molding, cool to room temperature to obtain chocolate.

[0027] Comparative Example 3: To investigate the effect of ultrasonic emulsification on chocolate, the chocolate was prepared from the following parts by weight of raw materials: 22 parts cocoa liquor, 12 parts cocoa butter, 15 parts milk fat, modified complex protein emulsifier: lactoferrin 0.51 parts, whey protein 1.29 parts, low sugar sweetener: erythritol / stevioside = 3:1 14 parts, milk powder 6 parts, lecithin 0.2 parts, natural antioxidant: rosemary extract / vitamin E = 1:2 1.0 parts.

[0028] The preparation method of the low-sugar, high-fat chocolate in this comparative example includes the following specific steps: S1. Dissolve lactoferrin in 100 mL of deionized water, add trypsin with an enzyme activity of 250 U / mg, the amount added is 0.8% of the lactoferrin mass, adjust the pH to 7.2, control the temperature at 38℃, and carry out the enzymatic hydrolysis reaction for 18 min to obtain enzymatically hydrolyzed lactoferrin peptides with a molecular weight of 300~1000 Da. S2. Mix enzymatically hydrolyzed lactoferrin peptides with whey protein at a mass ratio of 1:2.5, add transglutaminase with an activity of 100 U / g, and add 0.8% of the total mass of the protein mixture. Crosslink the mixture at 45°C for 75 min to obtain a modified composite protein emulsifier. S3. Weigh the milk fat and modified composite protein emulsifier, add them to the mixing container, and stir at 400 rpm for 20 minutes to complete emulsification; S4. Add cocoa liquor, cocoa butter, milk powder, lecithin, low-sugar sweetener, and natural antioxidant to the emulsification system. After mixing evenly, grind to a particle size of 12 μm. After molding, cool to room temperature to obtain chocolate.

[0029] Comparative Example 4: To investigate the effect of emulsifiers on chocolate, the chocolate was prepared from the following parts by weight of raw materials: 22 parts cocoa liquor, 12 parts cocoa butter, 15 parts milk fat, modified complex protein emulsifier: lactoferrin 0 parts, whey protein 0 parts, low sugar sweetener: erythritol / stevioside = 3:1 14 parts, milk powder 6 parts, lecithin 0.2 parts, natural antioxidant: rosemary extract / vitamin E = 1:2 1.0 parts, soy lecithin 2.0 parts.

[0030] The preparation method of low-sugar, high-fat chocolate in this embodiment includes the following specific steps: S1. Weigh out milk fat and soy lecithin, add them to a mixing container, and sonicate at low frequency for 5 minutes at a power of 200 W and a frequency of 20 kHz. Then switch to high frequency sonication at a power of 150 W and a frequency of 40 kHz for 3 minutes to complete emulsification. S4. Add cocoa liquor, cocoa butter, milk powder, lecithin, low-sugar sweetener, and natural antioxidant to the emulsification system. After mixing evenly, grind to a particle size of 12 μm. After molding, cool to room temperature to obtain chocolate.

[0031] Performance testing 1. Milk fat separation rate test Cut the chocolate sample into cubes of 2 cm × 2 cm × 1 cm, accurately weigh the initial mass, place the sample in a constant temperature incubator at 25℃ ± 0.5℃, control the relative humidity at 50~60%, and store for 3 months. After that, take out the sample, gently wipe the surface of the precipitated milk fat with filter paper, weigh the sample after wiping, and calculate the milk fat precipitation rate.

[0032] Table 1. Data on milk fat separation rate of each sample As can be seen from the comparative examples and comparative examples, enzymatic hydrolysis-crosslinking composite modification is the key to improving emulsion stability: the milk fat separation rates of comparative examples 1 and 2 are as high as 8.2% and 7.6% respectively, which are much higher than the 1.3~1.8% of the examples, indicating that single modification or no modification alone cannot solve the stability problem of high milk fat systems.

[0033] 2. Hardness test According to GB / T 19343-2016, the chocolate sample was cut into round pieces with a diameter of 20 mm and a thickness of 10 mm, and placed in an environment of 20℃ ± 1℃ for 2 h to equilibrate. Then, a texture analyzer was used with a P / 50 probe, the test speed was set to 1 mm / s, the compression distance to 5 mm, and the trigger force to 5 g. The sample was placed in the center of the stage of the texture analyzer, the test was started, and the maximum compression force was recorded, which is the sample hardness. Each sample was tested 5 times, and the average value was taken as the final result.

[0034] Table 2 Hardness test data for each sample 3. β-Crystal Content Test The chocolate sample was ground into a fine powder, passed through a 100-mesh sieve, and evenly spread in the sample cell. The X-ray diffractometer was set to a scanning range of 10°~30°, a scanning speed of 5° / min, and a step size of 0.02°. The diffraction pattern was scanned and recorded, and the characteristic peaks of the β-crystal form and other crystal forms were identified. The area of ​​each characteristic peak was integrated using the spectral analysis software. The β-crystal form content was calculated as: (total area of ​​β-crystal form characteristic peaks / total area of ​​all crystal form characteristic peaks) × 100%.

[0035] Table 3. Test results of β-crystal content for each sample Comparing the examples and comparative examples, it can be seen that segmented ultrasonic emulsification can significantly optimize the product texture: the β-crystal content of Comparative Example 3 is 88%, which is lower than 89~93% of the example, and the hardness is 6.3 N, which is higher than 5.8~6.2 N of the example, proving that ultrasound can promote the uniform dispersion of milk fat and improve the smoothness of the mouthfeel.

[0036] 4. Oxidative acid value test Referring to GB 5009.229-2016, weigh 5.00 g of chocolate sample into an Erlenmeyer flask, add 50 mL of a 1:1 (v / v) mixture of diethyl ether and isopropanol, and shake to dissolve. Add 3 drops of phenolphthalein indicator and titrate with 0.1 mol / L potassium hydroxide standard solution until the solution turns pink and does not fade for 30 seconds. Record the volume of standard solution consumed (V). Simultaneously, perform a blank control and record the volume of standard solution consumed in the blank control (V0). The formula for calculating the oxidative acid value is: Where c is the concentration of potassium hydroxide standard solution (mol / L) and m is the sample mass (g).

[0037] Table 4. Results of Oxidation Acid Value Test for Each Sample The low-sugar, high-fat chocolate of this invention exhibits a significant advantage in antioxidant properties, indicating that it can maintain good quality during storage. In contrast, the chocolates in the control group, particularly Comparative Example 4, show a higher oxidative acid value, indicating poor antioxidant performance, which may lead to a decline in flavor and a shortened shelf life.

[0038] 5. Total sugar content test Referring to GB 5009.8-2016, 2.0 g of chocolate sample was weighed, added to 50 mL of deionized water, heated in a 70℃ water bath to dissolve, cooled, and then diluted to 100 mL. The sample was filtered through a 0.45 μm filter membrane. The chromatographic conditions were as follows: a high-performance liquid chromatograph equipped with a 250 mm × 4.6 mm, 5 μm amino column; a mobile phase of acetonitrile-water (70:30 v / v); a flow rate of 1.0 mL / min; a column temperature of 35℃; and a differential refractive index detector. Sucrose standard solutions of different concentrations were prepared, injected, and measured. A standard curve was plotted with concentration on the x-axis and peak area on the y-axis. 10 μL of the filtrate was then injected, and the corresponding sugar concentration was determined from the standard curve based on the peak area. The total sugar content was then calculated.

[0039] Table 5. Results of total sugar content test for each sample Based on the total sugar content test results, Example 2 had a sugar content of 12 g / 100g, which is the lowest and meets the low sugar standard, demonstrating the best sugar control effect. Examples 1 and 3 had slightly higher sugar contents, but still lower than conventional chocolate. In contrast, the comparative example had a higher sugar content.

[0040] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A low-sugar, high-fat-ratio chocolate, characterized in that, The chocolate is prepared from the following ingredients in parts by weight: 20-25 parts cocoa liquor, 10-15 parts cocoa butter, 15-20 parts milk fat, 1.5-2.0 parts modified complex protein emulsifier, 12-15 parts low-sugar sweetener, 5-8 parts milk powder, 0.1-0.3 parts lecithin, and 0.5-1.5 parts natural antioxidant.

2. A method for preparing a low-sugar, high-fat-ratio chocolate, wherein the chocolate is as described in claim 1, characterized in that... The specific steps are as follows: S1. After hydrolyzing lactoferrin, mix it with whey protein, add transglutaminase to carry out cross-linking reaction, and obtain modified composite protein emulsifier. S2. Mix the modified composite protein emulsifier with milk fat, and perform low-frequency coarse emulsification at 15~25 kHz and high-frequency fine emulsification at 35~45 kHz in sequence; S3. Add low-sugar sweeteners and antioxidants to the emulsion system, and then grind, temper, and shape to obtain low-sugar, high-fat chocolate.

3. The method for preparing a low-sugar, high-fat-ratio chocolate according to claim 2, characterized in that, The lactoferrin is selected from one or more of trypsin, papain, and pepsin. The amount of enzyme added is 0.5-1% of the lactoferrin protein mass. The enzymatic hydrolysis pH is 7.0-7.5, the temperature is 35-40℃, the reaction time is 15-20 min, and the molecular weight of the lactoferrin hydrolysate peptide after enzymatic hydrolysis is 300-1000 Da.

4. The method for preparing a low-sugar, high-fat-ratio chocolate according to claim 2, characterized in that, The mass ratio of lactoferrin to whey protein is 1:2 to 1:3, the transglutaminase activity is 80 to 120 U / g, the cross-linking reaction temperature is 40 to 50℃, and the reaction time is 60 to 90 min.

5. The method for preparing a low-sugar, high-fat-ratio chocolate according to claim 2, characterized in that, After the crosslinking reaction is completed, the modified composite protein emulsifier is spray-dried at an inlet air temperature of 180-200°C and an outlet air temperature of 80-90°C to obtain modified composite protein powder with a particle size of 50-80 μm and a moisture content of 1-3%.

6. The method for preparing a low-sugar, high-fat-ratio chocolate according to claim 2, characterized in that, The low-sugar sweetener is one or more of erythritol, steviol glycosides and xylitol, with a mass ratio of 2:1 to 4:1, and the total amount added accounts for 10 to 15% of the total mass of the chocolate, and the total sugar content of the chocolate is 2 to 3 g / 100 g.

7. The method for preparing a low-sugar, high-fat-ratio chocolate according to claim 2, characterized in that, In step S3, the particle size of the ground material is 10~15 μm, and the β-crystal content is 90~95% during the temperature adjustment process.

8. The method for preparing a low-sugar, high-fat-ratio chocolate according to claim 2, characterized in that, The natural antioxidant is a compound of rosemary extract and vitamin E, with a mass ratio of 1:1 to 1:

3. The oxidative acid value of the chocolate is 0.5 to 1.0 mg / g after being stored at 25°C for 6 months.

9. A low-sugar, high-fat-ratio chocolate according to claim 1, characterized in that, The amount of modified complex protein emulsifier added to the chocolate is 1.5~2.0%, the milk fat separation rate is 1~2%, and the protein content is 5~10%.

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