阅读说明：本技术 一种利用微凝胶与辅色剂协同提高果汁色泽稳定性的方法 (Method for improving color stability of fruit juice by utilizing synergy of microgel and auxiliary color agent ) 是由 邓红 梁佳蕊 孟永宏 刘靓 郭玉蓉 田丹 于 2021-01-28 设计创作，主要内容包括：本发明公开了一种利用微凝胶与辅色剂协同提高果汁色泽稳定性的方法,通过添加辅色剂芥子酸与果汁中发色物质结合形成呈色基团,并利用微凝胶包封技术,采用喷射均质法使天然凝胶剂海藻酸钠微凝胶包封呈色基团,有效降低呈色基团与氧气等其他物质的接触,通过两种途径协同作用防止加工后的果汁发生非酶氧化导致果汁褪色,在不改变果汁口感的条件下保障果汁的色泽稳定性,延长果汁饮料的货架期。该方法原料天然、工艺简单、对需要长期储运的果汁具有较稳定的护色效果。(The invention discloses a method for improving color stability of fruit juice by utilizing synergy of microgel and a color adjuvant, which is characterized in that a color generation group is formed by combining erucic acid added as the color adjuvant and a color development substance in the fruit juice, and a microgel encapsulation technology is utilized, a spray homogenization method is adopted to encapsulate the color generation group by sodium alginate microgel of natural gel, so that the contact of the color generation group and other substances such as oxygen is effectively reduced, the color fading of the fruit juice caused by non-enzymatic oxidation of the processed fruit juice is prevented by the synergistic effect of two ways, the color stability of the fruit juice is ensured under the condition of not changing the taste of the fruit juice, and the shelf life of the fruit juice beverage. The method has natural raw materials and simple process, and has stable color protection effect on fruit juice which needs to be stored and transported for a long time.)

1. A method for improving color stability of fruit juice by utilizing synergy of microgel and auxiliary color agent is characterized by comprising the following steps:

(1) selecting fresh fruits, cleaning, peeling, cutting into pieces, juicing and filtering to obtain fruit juice;

(2) adding citric acid into the fruit juice to adjust the pH value of the fruit juice to 3-3.5, adding sinapic acid, and dissolving with the aid of ultrasound;

(3) dissolving sodium alginate in a part of the fruit juice, dissolving calcium chloride in another part of the fruit juice to obtain a fruit juice containing sodium alginate and a fruit juice containing Ca²⁺Cooling to room temperature;

(4) using a high pressure spray homogenizer to add Ca²⁺The fruit juice is placed in one chamber, the fruit juice containing sodium alginate is placed in the other chamber, the volume ratio of the two chambers is adjusted to be 10: 90-30: 70, a push rod driven by compressed air pushes the fruit juice placed at the tops of the two chambers at the pressure of 300-450 kPaA plug to allow the liquid to flow out of the chamber and through the small holes, creating a high turbulence, promoting the gelling of the sodium alginate, and collecting the juice forming the microgels;

(5) pasteurizing the microgel formed juice in the step (4), and cooling after hot canning.

2. The method of claim 1, wherein the microgel is used in combination with a color auxiliary agent to improve the color stability of the juice, and the method comprises the following steps: in the step (2), the addition amount of sinapic acid in the fruit juice is 80-120 mu g/mL.

3. The method of claim 1, wherein the microgel is used in combination with a color auxiliary agent to improve the color stability of the juice, and the method comprises the following steps: in the step (3), the concentration of sodium alginate in the sodium alginate-containing fruit juice is 0.5-1.5 mg/mL, and the content of Ca is²⁺The concentration of calcium chloride in the fruit juice is 9-11 mmol/L.

4. The method of claim 1, wherein the microgel is used in combination with a color auxiliary agent to improve the color stability of the juice, and the method comprises the following steps: in the step (4), Ca is sprayed by a high-pressure spray homogenizer²⁺The fruit juice is placed in one chamber, the fruit juice containing sodium alginate is placed in the other chamber, the volume ratio of the two chambers is adjusted to be 20:80, and a push rod driven by compressed air pushes pistons placed at the tops of the two chambers at the pressure of 300-400 kPa.

Technical Field

The invention belongs to the technical field of fruit juice preparation, and particularly relates to a method for improving the color stability of fruit juice by utilizing the cooperation of microgel and a color auxiliary agent.

Background

With the improvement of the productivity level of China and the quality of life of people, the requirements of people on the quality of food are higher and higher. Color is one of the important qualities affecting food products, particularly beverages, and is the first food product property most noticeable to consumers on the shelf, affecting the consumer's choice of that food product. Therefore, it is necessary to stabilize the color of the juice.

The existing method for protecting the color of the fruit juice mainly comprises the single treatment of adding a color fixative and a color auxiliary agent or pasteurization and the like. The prevention of color change of fruit juice by adding different color fixatives such as citric acid, beta-cyclodextrin and chlorophyll ketone is reported in patents CN109770166A, CN109430688A and CN107801889A, etc. CN110897061A, CN110692876A and the like perform pasteurization and high-pressure homogenization treatment on the color of the juice. CN111423960A adds amino acid, metal ion and organic acid as auxiliary color agent, xanthan gum, sodium carboxymethylcellulose as stabilizer to protect color of the compound passion fruit juice.

In the color protection method of the fruit juice, the formulas of the added color protection agent and the added auxiliary agent are complex, and the addition of a large amount of the substances inevitably affects the physical and chemical properties of the fruit juice such as flavor, solubility and the like, and the color protection effect of the fruit juice on certain fruit juices is not long. Therefore, the processing method has low cost and simple process, can obviously improve the auxiliary color effect and inhibit the fading phenomenon of the juice during storage and transportation, and has great significance.

Disclosure of Invention

The invention aims to solve the problems of low efficiency, short shelf life and the like of a single color-assisting technology of the existing fruit juice product, and provides a method for improving the color stability of fruit juice by utilizing the cooperation of microgel and a color-assisting agent so as to prevent the color of the fruit juice from changing during transportation, storage and sale.

Aiming at the purposes, the technical scheme adopted by the invention comprises the following steps:

1. selecting fresh fruits, cleaning, peeling, cutting into pieces, juicing and filtering to obtain the fruit juice.

2. Adding citric acid into the fruit juice to adjust the pH value of the fruit juice to 3-3.5, adding sinapic acid, and dissolving with the aid of ultrasound.

3. Dissolving sodium alginate in a part of the fruit juice, dissolving calcium chloride in another part of the fruit juice to obtain a fruit juice containing sodium alginate and a fruit juice containing Ca²⁺And cooling to room temperature.

4. Using a high pressure spray homogenizer to add Ca²⁺The fruit juice is placed in one chamber, the fruit juice containing sodium alginate is placed in the other chamber, the volume ratio of the two chambers is adjusted to be 10: 90-30: 70, a push rod driven by compressed air pushes a piston placed at the top of the two chambers at the pressure of 300-450 kPa, liquid flows out of the chambers and passes through small holes, high turbulence is generated, the sodium alginate is promoted to be gelatinized, and the fruit juice forming microgel is collected.

5. And (4) pasteurizing the juice of which the microgel is formed in the step (4), and cooling after hot canning.

In the step 2, the addition amount of the sinapic acid in the fruit juice is preferably 80-120 mu g/mL.

In the step 3, the concentration of sodium alginate in the sodium alginate-containing fruit juice is preferably 0.5-1.5 mg/mL, and Ca is preferably contained²⁺The concentration of calcium chloride in the fruit juice is 9-11 mmol/L.

In the step 4, Ca is added by using a high-pressure injection homogenizer²⁺The fruit juice containing sodium alginate is placed in one chamber, the fruit juice containing sodium alginate is placed in the other chamber, the volume ratio of the two chambers is preferably adjusted to be 20:80, and a push rod driven by compressed air pushes pistons placed at the tops of the two chambers at the pressure of 300-400 kPa.

The invention has the following beneficial effects:

according to the invention, the auxiliary agent sinapic acid is added to be combined with the chromogenic substance in the fruit juice to form the chromogenic group, the microgel encapsulation technology is utilized, the sodium alginate microgel encapsulates the chromogenic group by adopting a spray homogenization method, the contact of the sodium alginate microgel with other substances such as oxygen is effectively reduced, the color fading of the fruit juice caused by non-enzymatic oxidation of the processed fruit juice is prevented through the synergistic effect of the two ways, the color stability of the fruit juice is ensured, and the problem of short shelf life of the fruit juice beverage is solved. The method has natural raw materials and simple process, and has stable color protection effect on fruit juice which needs to be stored and transported for a long time.

Detailed Description

The present invention will be described in further detail with reference to examples, but the scope of the present invention is not limited to these examples.

Comparative example 1

1. Selecting 1kg of fresh apples, cleaning, peeling, cutting into blocks with the diameter of 3-4 cm, juicing, and filtering by using gauze to obtain apple juice.

2. Adding citric acid into 500mL of apple juice to adjust the pH value of the fruit juice to 3, separately adding standard solutions of natural phenolic acid auxiliary agents coumaric acid, sinapic acid, caffeic acid and chlorogenic acid with different concentrations to obtain apple juice with auxiliary agent concentrations of 50 mug/mL, 80 mug/mL and 100 mug/mL respectively, and performing ultrasonic-assisted dissolution at 30 ℃.

3. Pasteurizing the treated apple juice at 90 deg.C for 30 s, immediately hot-canning, and spray-cooling with cold water to room temperature.

The filled apple juice is stored for four weeks under the conditions that the indoor sunlight is not directly radiated and the temperature is 37 ℃, and the color change of the fruit juice is measured by a color difference meter. Changes in L value (brightness), a value (red-green color difference index) and b value (yellow-blue color difference index) of the fruit juice before and after storage were measured using a CR-400 type color difference meter, and Δ E ═ Δ L²+(Δa)²+(Δb)²]^1/2The juice color change was calculated. The results show that the color change of the stored juice is minimal when the concentration of the auxiliary agent contained in the juice is 100 mug/mL. When the auxiliary color agent added into the fruit juice is coumaric acid, the color change of the stored fruit juice is changed into delta E which is 41.4; when the auxiliary color agent added into the fruit juice is sinapic acid, the color change of the stored fruit juice is delta E which is 35.7; when the auxiliary color agent added into the fruit juice is caffeic acid, the color change of the stored fruit juice is that delta E is 39.9; when the auxiliary color agent added into the fruit juice is chlorogenic acid, the color change of the stored fruit juice is 38.2. Therefore, when 100. mu.g/mL sinapic acid was added to the juice as a co-pigment, the color stability of the juice was best.

Comparative example 2

1. Selecting 1kg of fresh apples, cleaning, peeling, cutting into blocks with the diameter of 3-4 cm, juicing, and filtering by using gauze to obtain apple juice.

2. Dissolving sodium alginate in 400mL of apple juice, magnetically stirring for 2 hours to fully dissolve the sodium alginate to obtain the apple juice containing 1mg/mL of sodium alginate, and cooling to room temperature (about 20 ℃); dissolving calcium chloride in 100mL apple juice to obtain 10mmol/L Ca²⁺The apple juice of (1).

3. Using a high pressure spray homogenizer to add Ca²⁺The apple juice in one chamber and the apple juice with sodium alginate in the other chamber, adjusting the volume ratio of the two chambers to 20:80, pushing the piston placed on the top of the two chambers with a push rod driven by compressed air at a pressure of 350kPa, causing the liquid to flow out of the chambers and through small holes, creating a high turbulence, causing the sodium alginate to gel, and collecting the apple juice enriched with microgels.

4. Pasteurizing the treated apple juice at 90 deg.C for 30 s, immediately hot-canning, and spray-cooling with cold water to room temperature.

The filled apple juice is stored for four weeks under the condition that the apple juice is not directly irradiated by sunlight indoors and the temperature is 37 ℃, and the color change of the apple juice is measured by a colorimeter. The results showed that the microgel formed in the juice was uniformly dispersed and the color change of the juice after storage was 44.8.

Example 1

1. Selecting 1kg of fresh apples, cleaning, peeling, cutting into blocks with the diameter of 3-4 cm, juicing, and filtering by using gauze to obtain apple juice.

2. Adding citric acid into 500mL of apple juice to adjust pH to 3, adding sinapic acid, and ultrasonic-assisted dissolving at 30 deg.C to obtain apple juice containing 100 μ g/mL of sinapic acid.

3. Dissolving sodium alginate in 400mL of apple juice, magnetically stirring for 2 hours to fully dissolve the sodium alginate to obtain the apple juice containing 1mg/mL of sodium alginate, and cooling to room temperature (about 20 ℃); dissolving calcium chloride in 100mL apple juice to obtain 10mmol/L Ca²⁺The apple juice of (1).

4. Using a high pressure spray homogenizer to add Ca²⁺Placing the apple juice inIn one chamber, apple juice containing sodium alginate is placed in the other chamber, the volume ratio of the two chambers is adjusted to be 20:80, a push rod driven by compressed air pushes a piston placed at the top of the two chambers at a pressure of 350kPa, liquid is made to flow out of the chambers and through small holes, high turbulence is generated, the gelation of sodium alginate is promoted, and the apple juice rich in microgel is collected.

5. Pasteurizing the treated apple juice at 90 deg.C for 30 s, immediately hot-canning, and spray-cooling with cold water to room temperature.

And (3) placing the filled apple juice indoors without direct sunlight, storing the apple juice for four weeks at the temperature of 37 ℃, and measuring the color change of the apple juice by using a colorimeter. The results show that the microgel formed in the apple juice has small particle size and good dispersity, and the color change of the stored apple juice is 16.3. The microgel-mediated auxiliary color of the fruit juice obviously improves the color stability of the apple juice after storage.

Example 2

1. Selecting 1kg of fresh pears, cleaning, peeling, cutting into blocks with the diameter of 3-4 cm, squeezing juice, and filtering with gauze to obtain pear juice.

2. Adding citric acid into 500mL of pear juice to adjust pH of the juice to 3, adding sinapic acid, and performing ultrasonic-assisted dissolution at 30 deg.C to obtain pear juice containing 100 μ g/mL of sinapic acid.

3. Dissolving sodium alginate in 400mL of pear juice, magnetically stirring for 2 hours to fully dissolve the sodium alginate to obtain pear juice containing 1mg/mL of sodium alginate, and cooling to room temperature (about 20 ℃); dissolving calcium chloride in 100mL pear juice to obtain Ca solution containing 10mmol/L Ca²⁺The pear juice.

4. Using a high pressure spray homogenizer to add Ca²⁺The pear juice is placed in one chamber, the pear juice containing sodium alginate is placed in the other chamber, the volume ratio of the two chambers is adjusted to be 20:80, a push rod driven by compressed air pushes a piston placed at the top of the two chambers at the pressure of 350kPa, liquid flows out of the chambers and passes through small holes, high turbulence is generated, the sodium alginate is promoted to be gelatinized, and the pear juice rich in microgel is collected.

5. Pasteurizing the treated pear juice at 90 deg.C for 30 s, immediately hot-canning, and spray-cooling with cold water to room temperature.

And (3) placing the filled pear juice indoors for direct irradiation without sunlight, storing the pear juice for four weeks at the temperature of 37 ℃, and measuring the color change of the pear juice by using a colorimeter. The result shows that the microgel formed in the pear juice is uniformly dispersed, and the color change of the pear juice after storage is 15.8.

In step 3 of this example, pear juices containing 0.5mg/mL and 1.5mg/mL sodium alginate were prepared separately, and the other steps were the same as described above. The result shows that when the concentration of the sodium alginate is 0.5mg/mL, the microgel formed in the pear juice is dispersed more uniformly, and the color change of the stored pear juice is that delta E is 19.9; when the concentration of sodium alginate is 1.5mg/mL, the microgel formed in the pear juice is dispersed unevenly, and the color change of the stored pear juice is 23.6; therefore, when the concentration of the sodium alginate is 1mg/mL, the color stability of the stored pear juice is optimal.

Example 3

1. Selecting 1.5kg of fresh navel oranges, cleaning, peeling, cutting into blocks with the diameter of 3-4 cm, squeezing and filtering by using gauze to obtain orange juice.

2. Adding citric acid to 500mL orange juice to adjust the pH of the juice to 3, adding sinapic acid, and ultrasonically assisting to dissolve at 30 deg.C to obtain 100 μ g/mL orange juice containing sinapic acid.

3. Dissolving sodium alginate in 400mL of orange juice, magnetically stirring for 2 hours to fully dissolve the sodium alginate to obtain 1mg/mL of orange juice, and cooling to room temperature (about 20 ℃); dissolving calcium chloride in 100mL orange juice to obtain a solution containing 10mmol/L Ca²⁺The orange juice of (4).

4. Using a high pressure spray homogenizer to add Ca²⁺Is placed in one chamber and orange juice containing sodium alginate is placed in the other chamber, the volume ratio of the two chambers is adjusted to 20:80, a push rod driven by compressed air pushes a piston placed on the top of the two chambers at a pressure of 350kPa, the liquid is made to flow out of the chambers and through small holes, high turbulence is generated, the gelation of sodium alginate is promoted, and the orange juice rich in microgel is collected.

5. Pasteurizing the treated orange juice at 90 deg.C for 30 s, immediately hot-canning, and spray-cooling with cold water to room temperature.

The filled orange juice is stored for four weeks in a room without direct sunlight at a temperature of 37 ℃, and the color change of the orange juice is measured by a colorimeter. The results show that the microgel formed in orange juice has a small particle size and a good dispersibility, and that the colour change of the juice after storage is ═ 17.1.

In step 4 of this embodiment, the other steps of adjusting the volume ratio of the two chambers to 10:90 and 30:70 respectively are the same as described above. The results show that at a volume ratio of 10:90, the microgel formed in the orange juice had a smaller particle size and a more general dispersion, and the color change of the orange juice after storage was 19.6; when the volume ratio of the two chambers is 30:70, the microgel formed in the orange juice has slightly larger grain size and better dispersity, and the color change of the stored orange juice is delta E which is 22.5; therefore, when the volume ratio of the two cavities is 20:80, the microgel has the most proper particle size, the best dispersion degree and the good color stability of the stored orange juice.

Example 4

1. Selecting 1kg of apples and 1kg of kiwi fruits, cleaning, peeling, cutting into blocks with the diameter of 3-4 cm, juicing, filtering with gauze, and mixing to obtain the apple-kiwi fruit composite juice.

2. Adding citric acid into 1000mL of apple-kiwi fruit composite juice to adjust the pH value of the juice to 3, adding sinapic acid, and performing ultrasonic-assisted dissolution at 30 ℃ to obtain composite juice containing 100 mu g/mL of sinapic acid.

3. Dissolving sodium alginate in 800mL of compound fruit juice, magnetically stirring for 2 hr to obtain compound fruit juice containing 1mg/mL of sodium alginate, and cooling to room temperature (about 20 deg.C); dissolving calcium chloride in 200mL of compound fruit juice to obtain a solution containing 10mmol/L Ca²⁺The compound fruit juice.

4. Using a high pressure spray homogenizer to add Ca²⁺The composite fruit juice containing sodium alginate is placed in one chamber, the composite fruit juice containing sodium alginate is placed in the other chamber, the volume ratio of the two chambers is adjusted to be 20:80, a push rod driven by compressed air pushes a piston placed at the top of the two chambers at the pressure of 350kPa, liquid flows out of the chambers and passes through a small hole to generate high turbulence, the sodium alginate is promoted to be gelatinized, and the sodium alginate is collectedThe compound juice rich in microgel is collected.

5. Pasteurizing the treated compound fruit juice at 90 deg.C for 30 s, immediately hot-canning, and spray-cooling with cold water to room temperature.

And (3) placing the filled compound juice indoors without direct sunlight, storing the compound juice for four weeks at the temperature of 37 ℃, and measuring the color change of the orange juice by using a colorimeter. The results show that the microgel formed in the composite juice had a small particle size and a good dispersibility, and the color change of the juice after storage was 18.3.

In step 4 of this embodiment, the push rods driven by compressed air push the pistons placed at the top of the two chambers at 300kPa, 350kPa, 400kPa, respectively, and the other steps are the same as described above. The result shows that when the pressure for pushing the piston is 300kPa, the particle size of the microgel formed in the compound fruit juice is smaller, the dispersion degree is better, and the color change of the stored fruit juice is delta E which is 20.5; when the pressure for pushing the piston is 400kPa, the particle size of the microgel formed in the compound fruit juice is small, the dispersion degree is slightly good, and the color change of the stored fruit juice is that delta E is 22.7; therefore, the color stability of the compound fruit juice is best when the spraying homogenizing pressure is 350 kPa.