Green-protecting agent for preserved actinidia arguta and application of green-protecting agent

Abstract

The invention discloses a green-protecting agent for preserved actinidia arguta and application of the green-protecting agent. Comprising 0.03%-0.07% of CaCl2, 0.2%-0.6% of copper acetate, 0.3%-0.7% of citric acid and 0.3%-0.7% of beta-cyclodextrine. And the balance of water. According to the method disclosed by the invention, the optimal green-protecting scheme is screened out by exploring the types, concentrations and composite effects of different green-protecting agents, so that the color change of the preserved actinidia arguta in the processing process is effectively controlled, and the green color of the preserved actinidia arguta is kept. The preserved actinidia arguta fruits produced by the process are emerald green in color, sour, sweet and delicious in taste and flexible in texture, and the flavor of the actinidia arguta fruits is reserved. The invention provides technical support and theoretical basis for industrial production of preserved actinidia arguta.

Description

Technical Field

[0001] The invention belongs to the technical field of food processing, and particularly relates to a green preservative for preserved Actinidia arguta fruit and application thereof. Background Art

[0002] As an emerging specialty fruit, Actinidia arguta (Chinese kiwifruit) is rich in various nutrients and is highly sought after by consumers. Processing it into preserved fruit not only prolongs its shelf life but also expands product offerings, boosting economic returns and increasing income for farmers and retailers. However, during processing, the fruit's original green color easily fades, severely impacting its appearance and value. Color is a key factor influencing consumers' first impressions of food, and for preserved kiwifruit, an alluring green color significantly enhances its market appeal.

[0003] Color changes during preserved fruit processing are a key factor affecting product quality. Zhang Lihua's research on the degradation mechanism of kiwifruit chlorophyll shows that under heating and acidic conditions, the magnesium ions in chlorophyll are easily replaced by hydrogen ions to form pheophytin, causing the color to change from bright green to brown-green. This process is influenced by multiple factors, including temperature, pH, metal ions, and oxidase activity. Wang Min and Liu Linwei further pointed out that chlorophyll degradation pathways include enzymatic reactions (such as chlorophyllase) and non-enzymatic reactions (such as thermal degradation and acid degradation), with non-enzymatic degradation predominating in preserved fruit processing.

[0004] Currently, research on the green preservation technology of Actinidia arguta fruit preserves is not in-depth and comprehensive enough. Existing green preservation methods have many problems in practical application, such as unsatisfactory green preservation effects and the introduction of too many additives that affect product flavor and safety. Summary of the Invention

[0005] The purpose of the present invention is to provide a green-preserving agent for preserved Actinidia arguta fruit and application thereof.

[0006] A greening agent for preserved Actinidia arguta fruit comprises 0.03-0.07% CaCl2, 0.2-0.6% copper acetate, 0.3-0.7% citric acid and 0.3-0.7% beta-cyclodextrin; the balance is water.

[0007] The preferred greening agent for preserved Actinidia arguta fruit comprises 0.05% CaCl2, 0.41% copper acetate, 0.51% citric acid and 0.51% β-cyclodextrin; the balance is water.

[0008] The invention discloses an application of the green protecting agent for preserved Actinidia arguta fruit in the preparation of preserved Actinidia arguta fruit.

[0009] A method for preparing preserved Actinidia arguta fruit is carried out according to the following steps:

[0010] (1) Pretreatment of Actinidia arguta: Remove the stems of Actinidia arguta and rinse with clean water, repeat 3-5 times, and then rinse and set aside;

[0011] (2) Alkali blanching: the kiwifruit obtained in step (1) is placed in a mixed solution of 0.06-0.12% Na2CO3 and 0.5-1.5% NaCl and blanched at 60-100°C for 20-40 seconds, and then the fruit is pierced after cooling;

[0012] (3) Use greening agent to ultrasonically protect and harden for 6-10 hours;

[0013] (4) Ultrasonic infiltration of sucrose solution for 6-10 h, and drying at 45-65 °C for 6-10 h.

[0014] Step (2) The kiwi fruit was placed in a mixed solution of 0.08% Na2CO3 and 1% NaCl and blanched at 80°C for 30 seconds.

[0015] The greening agent comprises 0.03-0.07% CaCl2, 0.2-0.6% copper acetate, 0.3-0.7% citric acid and 0.3-0.7% beta-cyclodextrin; the balance is water.

[0016] The power of the ultrasound is 100-180W.

[0017] The mass fraction of the sucrose solution is 20-40%.

[0018] Beneficial effects of the present invention: By exploring the types, concentrations, and combined effects of different greening agents, the present invention screens out the optimal greening scheme, effectively controlling the color changes of kiwifruit preserves during processing and maintaining the green color of the preserves. First, a single-factor experiment was conducted on the key factors of the kiwifruit preserve processing technology; then, a response surface experimental design was used, and based on the △a* and sensory evaluation of the preserves, a scientific and effective greening formula for kiwifruit preserves was determined. The optimal formula of the ultrasonic composite greening agent for kiwifruit preserves is: 0.41% copper acetate addition, 0.51% citric acid addition, and 0.51% β-cyclodextrin addition; the △a* of the preserves obtained was 3.414, and the sensory score was 94.25. The kiwifruit preserves produced by this process have a emerald green color, a sweet and sour taste, a soft and tough texture, and retain the flavor of kiwifruit. This study provides technical support and a theoretical basis for the industrial production of kiwifruit preserves. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a bar graph showing the effect of Na2CO3 solution on Δa*.

[0020] Figure 2 This is the effect of greening agent types on Δa*.

[0021] Figure 3 is the effect of copper acetate solution concentration on Δa*.

[0022] Figure 4 is the effect of citric acid solution concentration on Δa*.

[0023] Figure 5 is the effect of β-cyclodextrin solution concentration on Δa*.

[0024] Figure 6 3D response surface plot and contour plot showing the significance of the effect of quadratic interaction on Δa*.

[0025] Figure 7 3D response surface diagram and contour map showing the significance of the impact of quadratic interaction on sensory evaluation. DETAILED DESCRIPTION

[0026] To facilitate understanding of the present invention, the present invention will be described more fully below. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0027] Experimental Materials: Commercially ripe Actinidia chinensis ("Jiki No. 1," Brix 13-16%) were harvested on September 20, 2024, at the Actinidia chinensis orchard of Langfang Normal University. Fruits with moderate firmness, smooth surface, no pests or damage, and uniform shape, color, and size were selected and stored in a refrigerator at 4°C for subsequent testing. Three biological replicates were performed, each consisting of 10 fruits.

[0028] Data processing: The data were expressed as mean ± standard deviation, and SPSS 20.0 software was used for statistical analysis. The variance analysis used LSD (least significant difference) for difference test (P < 0.05), and Origin 2024 was used for drawing.

[0029] Example 1

[0030] Alkali boiling and blanching: The experimental study determined the blanching process parameters as follows: blanching in 1% NaCl solution at 80℃ for 30s and then quickly cooling with cold water. Under this blanching condition, Na2CO3 (0, 0.02%, 0.04%, 0.06%, 0.08%, 0.10%) was added respectively to determine the optimal alkali boiling solution concentration.

[0031] The experimental results are shown in Figure 1As the Na2CO3 solution concentration gradually increases, the value of Δa* gradually increases, reaching its maximum value at a Na2CO3 solution concentration of 0.08%. As the Na2CO3 solution concentration continues to increase, Δa* decreases. Therefore, a Na2CO2 solution concentration of 0.08% was selected as the optimal caustic soda solution concentration.

[0032] Example 2

[0033] In order to facilitate solution penetration and maintain the fruit shape, the ends of the soft-fleshed kiwifruit were removed and punctured and trimmed. Under these treatments, the fruits were immersed in 0.03% copper acetate solution for 8 hours at room temperature and atmospheric pressure, vacuum (0.07MPa), and ultrasound (140W) to observe the penetration effect of the greening agent.

[0034] The test results are shown in Table 1. Vacuum (0.07 MPa) and ultrasound (140 W) are helpful for the penetration of greening agent. According to the sensory evaluation scores of preserved fruits, ultrasound (140 W) was selected as the best way to soak the fruit.

[0035] Table 1 Effect of fruit soaking method on the penetration effect of greening agent

[0036]

[0037] Example 3

[0038] The preserved fruits were soaked in sucrose solutions of different concentrations (30%, 35%, and 40%) at 140W ultrasonic temperature for 8 hours, and then dried in an oven at 55°C for 8 hours. The optimal concentration of sucrose solution was determined based on the sensory evaluation of the preserved fruits.

[0039] The test results are shown in Table 2. The concentration of sucrose solution affects the sweetness and hardness of preserved fruit. As the concentration of sucrose solution increases, the sweetness of preserved fruit increases and the hardness decreases. Based on the sensory evaluation scores of preserved fruit, a sucrose solution concentration of 35% was selected as the optimal sucrose solution concentration.

[0040] Table 2 Effect of sucrose solution concentration on the taste of preserved fruit

[0041]

[0042] Example 4

[0043] Experimental research has determined that using a 0.05% CaCl2 solution as a hardener, immersing the fruit in an ultrasonic bath at 140W for 8 hours, and drying at 55°C for 8 hours produces preserved fruit with better morphology. Actinidia arguta was immersed in solutions of copper acetate, magnesium acetate, zinc acetate, zinc chloride, sodium D-isoascorbate, citric acid, phytic acid, and β-cyclodextrin (with the eight greening agents at mass fractions of 0.03%, 0.03%, 0.03%, 0.03%, 0.6%, 0.6%, and 0.6%, respectively). 0.05% CaCl2 was then added to the solutions. A control group, prepared without the greening agent, was used for the treatment of preserved Actinidia arguta. The fruit was immersed in an ultrasonic bath at 140W for 8 hours and then dried in an oven at 55°C for 8 hours. The Δa* of the samples was measured and recorded. (a* is measured by a colorimeter, positive values ​​indicate red, negative values ​​indicate green, Δa* is the change in red and green color before and after sample treatment, which is obtained by subtracting a* after treatment from a* before treatment. The larger the Δa* value, the better the green protection effect of the sample).

[0044] Depend on Figure 2 It can be seen that the Δa* of the three treatment groups of copper acetate, citric acid and β-cyclodextrin is greater than that of the control group (P < 0.05), that is, there are significant differences with the control group, which can indicate that copper acetate, citric acid and β-cyclodextrin have better greening effects.

[0045] Example 5

[0046] Green protection single-factor experimental design: Based on the test results of the selection of green protection agents for Actinidia arguta, copper acetate (0.01%, 0.02%, 0.03%, 0.04%, 0.05%), citric acid (0.4%, 0.5%, 0.6%, 0.7%, 0.8%) and β-cyclodextrin (0.4%, 0.5%, 0.6%, 0.7%, 0.8%) were selected, and 0.05% CaCl2 was added to the solution. The processing technology of Actinidia arguta preserved fruit without adding green protection agent was used as the control group. The fruit was immersed in ultrasound at 140W for 8h and dried in an oven at 55℃ for 8h. The Δa* of the sample was measured and recorded to determine the optimal concentration of the three green protection agents.

[0047] Depend on Figure 3 It can be seen that copper acetate has a significant effect on Δa*. As the copper acetate concentration increases, the value of Δa* gradually increases, reaching its maximum value at 0.04%. As the copper acetate concentration continues to increase, Δa* decreases. Therefore, the copper acetate concentration range of 0.03-0.05% was selected as the response surface analysis group.

[0048] Depend on Figure 4Citric acid significantly affects Δa*. As the citric acid concentration increases, Δa* gradually increases, reaching its maximum at 0.50%. Further increases in copper acetate concentration lead to a decrease in Δa*. Therefore, citric acid concentrations of 0.40-0.60% were selected as the response surface analysis group.

[0049] Depend on Figure 5 β-cyclodextrin significantly affects Δa*. Δa* gradually increases with increasing β-cyclodextrin concentration, reaching its maximum at 0.50%. Further increases in copper acetate concentration lead to a decrease in Δa*. Therefore, a range of β-cyclodextrin concentrations between 0.40% and 0.60% was selected for the response surface analysis.

[0050] Example 6

[0051] Response surface test of composite formula of greening agent: There are 17 groups in this test, groups 1-12 are factorial tests, and groups 13-17 are zero-point center tests, which are used to estimate the experimental error (Table 3).

[0052] Table 3 Response surface experimental design and results

[0053]

[0054]

[0055] According to the response surface test design scheme and the results shown in the table, the multivariate regression analysis fitting test results obtained a quadratic regression model with Δa*(Y1) as the objective function:

[0056] Y1=3.25+0.1402A+0.0710B+0.0764C+0.0032AB-0.0281AC+0.0001BC-0.5926

[0057] A 2 -0.4849B 2 -0.5471C 2 (1)

[0058] Quadratic regression model with sensory evaluation (Y2) as the objective function:

[0059] Y2=94.00+1.63A+1.13B+1.25C+0.000AB-0.25001AC-0.2500BC-5.50A 2 -4.00

[0060] B 2 -4.25C 2 (2).

[0061] Table 4 Analysis of variance table of regression equation with response value Δa*

[0062]

[0063]

[0064] Note: **.P<0.01, extremely significant difference; *.P<0.05, significant difference.

[0065] From the variance analysis in Table 4, it can be seen that when the response value is Δa*, the regression equation model is extremely significant (P < 0.01), the lack of fit term of the equation is not significant (P > 0.05), and R 2 =0.9952, R 2 Adj = 0.9891, indicating that the regression model has a good fit with the actual value. This model can be used to analyze and predict the compound formula of the greening agent for preserved kiwifruit. The variance analysis of the regression model shows that the items with the most significant effect on Δa* are A, B, C, and A. 2 、B 2 、C 2 The order of influence of various factors on Δa* is copper acetate > β-cyclodextrin > citric acid.

[0066] Table 5 Analysis of variance table of regression equation for sensory evaluation

[0067]

[0068]

[0069] Note: **.P<0.01, extremely significant difference; *.P<0.05, significant difference.

[0070] From the variance analysis in Table 5, it can be seen that when the response value is sensory evaluation, the regression equation model is extremely significant (P < 0.01), the lack of fit term of the equation is not significant (P > 0.05), and R 2 =0.9712, R 2 Adj = 0.9342, indicating that the regression model has a good fit with the actual value, and this model can be used to analyze and predict the compound formula of the greening agent for preserved kiwi fruit. The variance analysis of the regression model shows that the items with the most significant impact on sensory evaluation are A, B, C, and A. 2 、B 2 、C 2 The order of influence of various factors on sensory evaluation was copper acetate > β-cyclodextrin > citric acid.

[0071] The comparative analysis of the significance of the effect of quadratic interaction on Δa* is shown in Figure 6 .Depend on Figure 6As shown in Figure A, under the interaction between copper acetate and citric acid, when the β-cyclodextrin concentration is kept constant, Δa* changes significantly as the citric acid concentration varies within the range of 0.4-0.8%, resulting in a significant increase in the steepness of the curve, with Δa* initially increasing and then decreasing. Furthermore, when the citric acid concentration is kept constant and the copper acetate concentration is varied within the range of 0.03-0.05%, the magnitude of the change in Δa* is even more pronounced in the 3D graph than when the copper acetate concentration is kept constant and citric acid is used as the independent variable. This analysis indicates that under the interaction of these two factors, copper acetate (A) has a more significant effect on Δa* than citric acid (B).

[0072] Depend on Figure 6 As shown in Figure B, under the interaction between copper acetate and β-cyclodextrin, with a fixed citric acid concentration, Δa* undergoes a significant change as β-cyclodextrin concentration varies within the range of 0.4-0.8%, resulting in a significant steepness in the curve, with Δa* initially increasing and then decreasing. Furthermore, when β-cyclodextrin is kept constant and copper acetate concentration varies within the range of 0.03-0.05%, the magnitude of the change in Δa* is even more pronounced in the 3D graph than when β-cyclodextrin is used as the independent variable while copper acetate is kept constant. This analysis indicates that under the interaction of these two factors, copper acetate (A) has a more significant effect on Δa* than β-cyclodextrin (C).

[0073] Depend on Figure 6 As shown in Figure C, under the interactive effect of citric acid and β-cyclodextrin, with a fixed copper acetate concentration, Δa* changes significantly as the citric acid concentration varies within the range of 0.4-0.8%, resulting in a significant increase in the steepness of the curve, with Δa* initially increasing and then decreasing. Furthermore, when citric acid is kept constant and β-cyclodextrin concentration is varied within the range of 0.4-0.8%, the magnitude of the change in Δa* is even more pronounced in the 3D graph than when β-cyclodextrin is kept constant and citric acid is used as the independent variable. This analysis indicates that under the interactive effect of these two factors, β-cyclodextrin C has a more significant effect on Δa* than citric acid B.

[0074] Comparative analysis of the significance of the effects of secondary interactions on sensory evaluation can be found in Figure 7 ,Depend on Figure 7As shown in Figure A, under the interaction between copper acetate and citric acid, with a fixed β-cyclodextrin concentration, varying the citric acid concentration within the range of 0.4-0.8%, the sensory evaluation significantly changes, resulting in a sharper slope of the curve and a trend of initial increase followed by a decrease. Furthermore, when the citric acid concentration is kept constant and the copper acetate concentration is varied within the range of 0.03-0.05%, the magnitude of the change in the 3D graph is even more pronounced than when the copper acetate concentration is kept constant and citric acid is used as the independent variable. This analysis indicates that under the interaction of these two factors, copper acetate (A) has a more significant impact on sensory evaluation than citric acid (B).

[0075] Depend on Figure 7 As shown in Figure B, under the interaction between copper acetate and β-cyclodextrin, with a fixed citric acid concentration, sensory evaluation changes significantly as β-cyclodextrin concentration changes within the 0.4-0.8% range. This results in a significant steepness in the curve, with the sensory evaluation trend initially increasing and then decreasing. Furthermore, when β-cyclodextrin is kept constant and copper acetate concentration is varied within the 0.03-0.05% range, the magnitude of the changes in the 3D graph is even more pronounced than when copper acetate is kept constant and β-cyclodextrin is used as the independent variable. This analysis indicates that under the interaction of these two factors, copper acetate A has a more significant impact on sensory evaluation than β-cyclodextrin C.

[0076] Depend on Figure 7 As shown in Figure C, under the interactive effect of citric acid and β-cyclodextrin, with a fixed copper acetate concentration within the range of 0.4-0.8%, the sensory evaluation significantly changes, resulting in a significant steepness in the curve and a trend of initial increase followed by decrease. Furthermore, when β-cyclodextrin concentration is varied within the range of 0.4-0.8% while citric acid is fixed, the magnitude of the changes in the 3D graph is even more pronounced than when β-cyclodextrin is fixed and citric acid is used as the independent variable. This analysis indicates that under the interaction of these two factors, β-cyclodextrin C has a more significant impact on sensory evaluation than citric acid B.

[0077] The calculation of the response surface quadratic regression equation using Design-Expert13 software showed that the simulated optimal greening agent formula combination for this 3-factor 3-level experiment was: copper acetate 0.041%, citric acid 0.510% and β-cyclodextrin 0.510%. Through the screening system and condition design of this model, the final Δa* was 3.264 and the sensory evaluation was 94.269.

[0078] The model was validated. After predicting the regression model, the optimal greening agent formula and sensory evaluation criteria were identified. Six validation tests were repeated using the corresponding screening system and conditions, and statistical analysis was performed. The resulting Δa* was 3.414±0.342, and the sensory evaluation score was 94.25±1.682. The actual Δa* and sensory scores were close to the predicted results, confirming that the greening agent compound formula for preserved kiwifruit is scientifically proven and effective.

[0079] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A green-protecting agent for preserved Actinidia arguta fruit, characterized in that: The invention comprises 0.03-0.07% CaCl2, 0.2-0.6% copper acetate, 0.3-0.7% citric acid and 0.3-0.7% beta-cyclodextrin; the balance is water.

2. The green-protecting agent for preserved Actinidia arguta fruit according to claim 1, characterized in that It includes 0.05% CaCl2, 0.41% copper acetate, 0.51% citric acid and 0.51% β-cyclodextrin; the balance is water.

3. Use of the green-protecting agent for preserved Actinidia arguta fruit according to claim 1 in the preparation of preserved Actinidia arguta fruit.

4. A method for preparing preserved Actinidia arguta fruit, characterized in that: Follow these steps: (1) Pretreatment of Actinidia arguta: Remove the stems of Actinidia arguta and rinse with clean water, repeat 3-5 times, and then rinse and set aside; (2) alkaline boiling and blanching: the kiwi fruit prepared in step (1) is placed in a mixed solution of 0.06-0.12% Na2CO3 and 0.5-1.5% NaCl and blanched at 60-100°C for 20-40 seconds, and the fruit is pierced after cooling; (3) Use greening agent to ultrasonically protect and harden for 6-10 hours; (4) Ultrasonic infiltration of sucrose solution for 6-10 h, and drying at 45-65 °C for 6-10 h.

5. The method for preparing the preserved Actinidia arguta fruit according to claim 4, wherein: Step (2) blanching the kiwifruit in a mixed solution of 0.08% Na2CO3 and 1% NaCl at 80°C for 30 seconds.

6. The method for preparing the preserved Actinidia arguta fruit according to claim 4, wherein: The greening agent comprises 0.03-0.07% CaCl2, 0.2-0.6% copper acetate, 0.3-0.7% citric acid and 0.3-0.7% beta-cyclodextrin; the balance is water.

7. The method for preparing preserved Actinidia arguta fruit according to claim 4, wherein: The power of the ultrasound is 100-180W.

8. The method for preparing preserved Actinidia arguta fruit according to claim 4, wherein: The mass fraction of the sucrose solution is 20-40%.

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