Curcumin fresh-keeping emulsion as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of storage and fresh keeping of fruits and vegetables, and particularly relates to a curcumin fresh-keeping emulsion as well as a preparation method and application thereof. The preparation method comprises the following steps: mixing and stirring sodium carboxymethyl cellulose, a curing agent, a plasticizer and a curcumin-peony seed oil mixed solution, homogenizing, carrying out ultrasonic treatment to obtain a curcumin fresh-keeping emulsion, uniformly coating a degradable fresh-keeping bag with the curcumin fresh-keeping emulsion, and drying to obtain the degradable curcumin fresh-keeping bag. The fruit preservative can effectively delay reduction of indexes such as weight loss, hardness and soluble solids of fruits, inhibit increase of rotting rate, maintain sensory quality and nutritional value to the greatest extent and prolong the fresh-keeping period of the fruits and vegetables, and is high in safety, non-toxic, harmless and environment-friendly; the operation is simple, the preparation time is short, the production cost is greatly reduced, and large-scale marketization application is favorably realized.

Description

Technical Field

[0001] The invention belongs to the technical field of fruit and vegetable storage and preservation, and particularly relates to a curcumin fresh-keeping emulsion and a preparation method and application thereof. Background Art

[0002] Fresh-keeping packaging is one of the important means to maintain the quality of fruits and vegetables and prevent mechanical damage during storage and transportation. Reasonable fresh-keeping packaging is one of the important means to protect fruits and vegetables from environmental pollution, ensure the safety and quality of fruits and vegetables, reduce the decay rate and extend the storage period. With the continuous expansion of my country's fresh food e-commerce, fruit and vegetable home delivery and other businesses, higher requirements are put forward for fruit and vegetable fresh-keeping packaging.

[0003] Curcumin is a natural phenolic food additive extracted from the rhizome of the plant turmeric (Curcuma longa) and can be used as a spice and food colorant. In recent years, curcumin has been shown to have anti-inflammatory and anticancer activities. At the same time, curcumin has antibacterial activity against bacteria such as Staphylococcus aureus, Escherichia coli, Bacillus cereus and Pseudomonas aeruginosa after functionalization. Due to its antioxidant, antibacterial and safety properties, it has been used as a functional ingredient in food preservation films. However, there are no reports on the use of coating technology to directly fix the preservation emulsion with curcumin as the core ingredient on the surface of the preservation packaging.

[0004] Peony seed oil is rich in nutrition and has unique biological activity and physiological effects. Among them, unsaturated fatty acids are as high as 92%, α-linolenic acid is 42%, oleic acid is 24.18%, and linoleic acid is 20.35%. Many indicators exceed olive oil, which is known as "liquid gold". It was approved as a new resource food by the Ministry of Health on March 22, 2011. Peony seed oil not only has obvious antioxidant effects, but also can be used as a natural antioxidant in other products to improve the antioxidant capacity of the target product. At the same time, peony seed oil has good in vivo anti-free radical damage activity, and its intensity is even significantly stronger than the natural antioxidant salvianolic acid A. However, there are few reports on the application of peony seed oil in the preservation of fruits and vegetables.

[0005] At present, there are many types of fruit and vegetable fresh-keeping packaging, mainly including modified atmosphere fresh-keeping packaging, active fresh-keeping packaging, nano fresh-keeping packaging, etc. However, most of them require many tedious processes such as nano synthesis, and the R&D and preparation costs are too high to achieve industrial promotion. Ordinary packaging cannot achieve long-term fresh-keeping and cannot meet the requirements of consumers and fruit and vegetable suppliers. Summary of the invention

[0006] In order to overcome the deficiencies of the above-mentioned prior art, the object of the present invention is to provide a curcumin fresh-keeping emulsion and a preparation method and application thereof. To achieve the above-mentioned object, the present invention provides the following technical solutions:

[0007] A method for preparing a curcumin fresh-keeping emulsion, the specific steps are as follows:

[0008] (1) mixing curcumin and peony seed oil to obtain a mixed solution, stirring the mixed solution with a magnetic stirrer at 1200 rpm and 70° C. for 0.5 h to obtain a curcumin-peony seed oil mixed solution;

[0009] (2) A 0.01-0.03 g / mL sodium carboxymethyl cellulose aqueous solution, a curing agent, a plasticizer, and a curcumin-peony seed oil mixture are stirred in a magnetic stirrer, homogenized, and ultrasonicated to obtain a curcumin fresh-keeping emulsion.

[0010] Preferably, in step (1), the mass ratio of curcumin to peony seed oil is 2:3; 1 w / w % of anhydrous ethanol of curcumin is added to the mixed solution and then stirred.

[0011] Preferably, in step (2), the plasticizer is glycerol, and the curing agent is Tween 80.

[0012] Preferably, the plasticizer in step (2) is 15w / w%-20w / w% of sodium carboxymethyl cellulose; the curing agent is 2w / w%-5w / w% of sodium carboxymethyl cellulose; and the curcumin-peony seed oil mixture is 20w / w%-50w / w% of sodium carboxymethyl cellulose.

[0013] Preferably, the specific steps in step (2) are: dissolving sodium carboxymethyl cellulose in deionized water, stirring with a magnetic stirrer at 1000 rpm for 2-5 hours until the sodium carboxymethyl cellulose is completely dissolved, to obtain a sodium carboxymethyl cellulose aqueous solution; adding a plasticizer to the sodium carboxymethyl cellulose aqueous solution, stirring at 1000 rpm for 0.5 hours; then adding a curing agent, stirring with a magnetic stirrer at 800 rpm for 0.25-1.5 hours, until it is completely dissolved, adding a curcumin-peony seed oil mixture, stirring with a magnetic stirrer at 800 rpm for 0.5 hours, to obtain a solution A; homogenizing the solution A with a homogenizer at 12000 rpm, and then standing; and obtaining a curcumin fresh-keeping emulsion after ultrasonication.

[0014] Preferably, in step (2), the homogenization time of solution A is 5-15 min, and the standing time is 2-5 min; further preferably, the homogenization time is 8 min, and the standing time is 2 min.

[0015] Preferably, the ultrasound in step (2) is performed using a 15 nm ultrasound probe for ultrasonic destruction, the number of ultrasounds is 10 times, each time for 60 seconds, and the interval time is 5 seconds, so as to reduce the droplet size.

[0016] A degradable fresh-keeping bag coated with curcumin, wherein the surface of the fresh-keeping bag is coated with the above-mentioned curcumin fresh-keeping emulsion; a method for preparing the fresh-keeping bag comprises the following steps:

[0017] ① Evenly distribute the curcumin fresh-keeping emulsion on the inner side of the bottom seal of the biodegradable fresh-keeping bag;

[0018] ② Place the sealed bottom end of the curcumin fresh-keeping emulsion in step ① on the scraper side of the coating machine, so that the degradable fresh-keeping bag can be extended as flatly as possible on the working surface of the coating machine, and use the vacuum adsorption function of the coating machine itself to make the degradable fresh-keeping bag be adsorbed flatly on the working surface;

[0019] ③ Set the required coating thickness on the coating machine, and use the coating machine's scraper to slowly apply the curcumin fresh-keeping emulsion from the inner side of the bottom end of the seal of the degradable fresh-keeping bag to 1-2 cm away from the open end, and then control the coating machine scraper to run from 1-2 cm from the open end back to the bottom end of the seal, and apply it multiple times until the curcumin fresh-keeping emulsion is evenly distributed on the inner wall of the degradable fresh-keeping bag;

[0020] ④ Place the evenly coated curcumin fresh-keeping bag in a drying environment at 55°C to dry, and obtain a degradable curcumin fresh-keeping bag.

[0021] Preferably, the curcumin fresh-keeping emulsion in step ③ is coated with a thickness of 50-250 μm.

[0022] Preferably, the drying time in step ④ is 12h-30h.

[0023] The present invention also provides the use of the above-mentioned degradable curcumin fresh-keeping bag in the preservation of fruits and vegetables;

[0024] Preferably, when the fruits and vegetables are CO2-resistant fruits and vegetables, the side of the curcumin degradable fresh-keeping bag coated with the fresh-keeping emulsion is used as the inner wall of the fresh-keeping bag, and the fruits and vegetables are directly packaged for use;

[0025] When the fruits and vegetables are sensitive to CO2 concentration or are in the fresh logistics process, the curcumin degradable fresh-keeping bag is punched by laser technology to prepare curcumin degradable microporous modified atmosphere packaging; further preferably, under an environment of 15°C-20°C, 35-45 curcumin degradable microporous modified atmosphere packages with a pore size of 150-250 μm are selected to be prepared; under an environment of -4°C-8°C, 15-25 curcumin degradable microporous modified atmosphere packages with a pore size of 100-200 μm are selected to be prepared.

[0026] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0027] (1) The curcumin fresh-keeping emulsion has a strong antioxidant capacity and can extend the shelf life of fruits and vegetables. The present invention uses a coating technology to directly solidify the curcumin fresh-keeping emulsion on the surface of an ordinary packaging bag, which can be directly used as a fresh-keeping bag. It can effectively delay the reduction of fruit weight loss, hardness, soluble solids and other indicators, inhibit the increase of decay rate, maintain sensory quality and nutritional value to the greatest extent, and extend the shelf life of fruits and vegetables. It is highly safe, non-toxic and harmless, and environmentally friendly.

[0028] (2) The curcumin fresh-keeping emulsion is directly solidified on the surface of the fresh-keeping bag by using coating technology. Compared with other functional fresh-keeping packaging, the operation is simple and the preparation time is short, which greatly reduces the production cost and is conducive to large-scale market application. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a graph showing the changes in gas composition (O2, CO2) in the bags of Comparative Example 1-2 and Example 1-2;

[0030] Figure 2 It is a comparison chart of the DPPH and ABTS free radical scavenging capacity per square centimeter of the packaging bag in Comparative Example 1 and Example 1;

[0031] Figure 3 This is a diagram showing changes in cherry fruit during storage of Comparative Example 1-2 and Example 1-2;

[0032] Figure 4 It is a graph showing the change in the rot rate of cherries during storage of Comparative Example 1-2 and Example 1-2;

[0033] Figure 5 Cherry L during storage of Comparative Example 1-2 and Example 1-2 * value, a * Value, b * Value, titratable acid content, soluble solid content, reducing sugar content;

[0034] Figure 6 This is a graph showing changes in Semati apricot fruit during storage in Comparative Examples 3-4 and Example 3;

[0035] Figure 7 The graphs of weight loss rate and decay rate of Semati apricots during storage of Comparative Examples 3-4 and Example 3 are shown;

[0036] Figure 8 This is a graph showing the hardness change of Semati apricots during storage in Comparative Examples 3-4 and Example 3;

[0037] Fig. 9 Comparative Examples 3-4 and Example 3 Storage of Semati Apricot L * value, a * Value, b *Value, titratable acid content, soluble solids content and reducing sugar content. DETAILED DESCRIPTION

[0038] In order to clearly illustrate the technical features of the present invention, the present invention is described below through specific implementation methods. At the same time, the following examples are provided to better further understand the present invention, but are not limited to the best implementation method, and do not limit the content and protection scope of the present invention. Any product identical or similar to the present invention obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with other prior arts falls within the protection scope of the present invention.

[0039] Example 1

[0040] A kind of preparation method of curcumin fresh-keeping emulsion

[0041] (1) Curcumin and peony seed oil were mixed (mass ratio of 2:3), and 1 w / w% of anhydrous ethanol was added to the mixture. The mixture was stirred for 0.5 h at 1200 rpm and 70° C. using a magnetic stirrer to obtain a curcumin-peony seed oil mixture.

[0042] (2) 1 g of sodium carboxymethyl cellulose was dissolved in 100 mL of deionized water, and stirred at 1000 rpm with a magnetic stirrer for 2 h until the sodium carboxymethyl cellulose was completely dissolved to obtain a sodium carboxymethyl cellulose aqueous solution; glycerol (15 w / w% of sodium carboxymethyl cellulose) was added to the sodium carboxymethyl cellulose aqueous solution, and the magnetic stirrer was continued to stir for 0.5 h at 1000 rpm; Tween 80 (2 w / w% of sodium carboxymethyl cellulose) was then added, and the magnetic stirrer was stirred at 800 rpm for 0.25 h; finally, a mixed solution of curcumin-peony seed oil (20 w / w% of sodium carboxymethyl cellulose) was added, and the magnetic stirrer was stirred at 800 rpm for 0.5 h to obtain solution A; solution A was homogenized at 12000 rpm for 8 min, and then allowed to stand for 2 min. A 15 nm ultrasonic probe was used for ultrasonic destruction, and the number of ultrasonications was 10 times, each time for 60 s, with an interval of 5 s, to obtain a curcumin fresh-keeping emulsion.

[0043] A method for preparing a degradable curcumin fresh-keeping bag

[0044] ① Take a 40cm (length) * 30cm (width) biodegradable fresh-keeping bag, add the above-mentioned curcumin fresh-keeping emulsion to the inner side of the bottom of the 30cm sealed end, evenly distribute it, place the sealed bottom on the scraper side of the coating machine, and spread it flat on the work surface of the wire rod scraper integrated coating machine. After turning on the vacuum adsorption, use a scraper to apply 100μm thickness, apply it to 2cm away from the open end, and apply it back and forth 10 times.

[0045] ② The degradable fresh-keeping bag coated in step ① is sent to an electric hot air dryer and dried at 55° C. for 18 h to obtain a degradable curcumin fresh-keeping bag.

[0046] The above-mentioned biodegradable curcumin fresh-keeping bags were used to pack 1 kg of "American Red" cherries (fruits and vegetables that are sensitive to CO2 concentrations) without mechanical damage and pests. After the bags were tied, they were placed in a 23±2℃ temperature box for storage and preservation, and relevant indicators were measured every 3 days.

[0047] Example 2

[0048] A method for preparing a degradable curcumin fresh-keeping bag

[0049] The difference from Example 1 is that the degradable curcumin fresh-keeping bag obtained in step ② of Example 1 is used to prepare 20 micropores with a pore size of 200 μm by using an ultraviolet laser puncher, and then 1 kg of "American Red" cherries without mechanical damage and pests and diseases are packed, and after being tied, they are placed in a temperature box at 23±2°C for storage and preservation, and relevant indicators are measured every 3 days.

[0050] Example 3

[0051] A kind of preparation method of curcumin fresh-keeping emulsion

[0052] (1) Curcumin and peony seed oil were mixed (mass ratio of 2:3), and 1 w / w% of anhydrous ethanol was added to the mixture. The mixture was stirred for 0.5 h at 1200 rpm and 70° C. using a magnetic stirrer to obtain a curcumin-peony seed oil mixture.

[0053] (2) Dissolve 2 g of sodium carboxymethyl cellulose in 100 mL of deionized water, stir with a magnetic stirrer at 1000 rpm for 2 h until the sodium carboxymethyl cellulose is completely dissolved, and obtain a sodium carboxymethyl cellulose aqueous solution; continue to stir glycerol (18 w / w% of sodium carboxymethyl cellulose) with a magnetic stirrer at 1000 rpm for 0.5 h; then add Tween 80 (4 w / w% of sodium carboxymethyl cellulose) and stir with a magnetic stirrer at 800 rpm for 0.25 h; finally add a mixture of curcumin-peony seed oil (40 w / w% of sodium carboxymethyl cellulose) and stir with a magnetic stirrer at 800 rpm for 0.5 h to obtain solution A; homogenize solution A at 12000 rpm for 8 min and let it stand for 2 min. Use a 15 nm ultrasonic probe for ultrasonic destruction, the number of ultrasonications is 10 times, each time for 60 s, and the interval time is 5 s. The curcumin fresh-keeping emulsion is obtained.

[0054] A method for preparing a degradable curcumin fresh-keeping bag

[0055] ① Take a 40cm (length) * 40cm (width) biodegradable fresh-keeping bag, add the above-mentioned curcumin fresh-keeping emulsion to the inner side of the bottom of the 40cm sealed end, evenly distribute it, place the sealed bottom on the scraper side of the coating machine, and spread it flat on the work surface of the wire rod scraper integrated coating machine. After turning on the vacuum adsorption, use a scraper to apply 120μm thickness, apply it to 1cm away from the open end, and apply it back and forth 15 times.

[0056] ② The degradable fresh-keeping bag coated in step ① is sent to an electric hot air drying machine and dried at 55° C. for 24 hours to obtain a degradable curcumin fresh-keeping bag.

[0057] The above-mentioned biodegradable curcumin fresh-keeping bags were used to pack 1.2 kg of Semati apricots (CO2-resistant fruits and vegetables) without mechanical damage and pests and diseases. After the bags were tied, they were stored in a 0±3°C temperature box for preservation, and relevant indicators were measured every 7 days.

[0058] Comparative Example 1

[0059] The difference between this comparative example and Example 1 is that the "American Red" cherries are directly packaged in ordinary biodegradable fresh-keeping bags not coated with the curcumin fresh-keeping emulsion.

[0060] Comparative Example 2

[0061] The difference between this comparative example and Example 2 is that the micropores are prepared in an ordinary degradable fresh-keeping bag not coated with the curcumin fresh-keeping emulsion and then the "American Red" cherries are directly packaged.

[0062] Comparative Example 3

[0063] The difference between this comparative example and Example 3 is that the Semati apricots are not packaged in any fresh-keeping bags.

[0064] Comparative Example 4

[0065] The difference between this comparative example and Example 3 is that the Semaiti apricots are directly packaged in common degradable fresh-keeping bags not coated with the curcumin fresh-keeping emulsion.

[0066] Determination methods of various indicators:

[0067] Hardness (N): measured by TMS-PRO texture analyzer. The hardness of the sample's equator is measured vertically using a disc probe. Test parameters: test rate 60mm / min, compression degree 25%, minimum trigger force 0.75N. The test results are analyzed and calculated by TMS-Pro control software.

[0068] Weight loss rate (%): Weighing is performed using an electronic scale. On day 0, the processed samples of each group are weighed together with the fresh-keeping bag and recorded as m0. The weight measured at the subsequent storage time is recorded as m. When calculating the mass difference, the mass measured at the storage time point is subtracted from the mass on day 0 to obtain the mass difference. The weight loss rate is expressed as W, and the calculation formula is as follows:

[0069]

[0070] Decay rate (%): Each time the sample quantity of each group is measured, the number of rotten samples is recorded as X1, and the number of rotten samples is recorded as X2. The percentage of the number of rotten samples X2 to the total number of samples in each group X1 is calculated as the decay rate, and the calculation formula is as follows:

[0071]

[0072] Soluble solids ( 。 B): Use a handheld refractometer for measurement. Homogenize the pulp of 3 fruits, squeeze out the juice with gauze, and drop it onto the test mirror for measurement (before each measurement, wipe it with deionized water and adjust it to 0). The results are 。 B means.

[0073] Titratable acid (%): Determined by potentiometric titration. Take 30g pulp homogenate, weigh 10g homogenate, dilute to 100mL volumetric flask with deionized water, let stand for 30min and filter. Take 20.0mL filtrate, use automatic potentiometric titrator, titrate with 0.1mol / L NaOH solution to the end point pH 8.21, the acid conversion coefficient is 0.067 based on malic acid, and the calculation formula is as follows:

[0074]

[0075] In the formula, V represents the total volume of the sample extract (100 mL); V s represents the volume of the filtrate taken during titration (20.0 mL); c represents the NaOH concentration (0.1 mol / L); V1 represents the volume of NaOH consumed in titrating the filtrate, mL; V0 represents the volume of NaOH consumed in titrating deionized water, mL; f represents the acid conversion factor in terms of malic acid (0.067); m represents the sample mass (30 g).

[0076] Reducing sugar (%): 3,5-dinitrosalicylic acid method. After homogenizing the sample with deionized water in a ratio of 1:1, weigh 1g into a 25mL graduated test tube and make up to volume with deionized water. Place the 25mL graduated test tube containing the sample in an 80℃ constant temperature water bath for 30 minutes, cool to room temperature, then transfer to a 100ml volumetric flask and make up to volume with deionized water. After mixing, let it stand for 10 minutes and filter to obtain the reducing sugar extract. Take 2mL of reducing sugar extract and 1.5mL of DNS reagent and add them to a 25mL graduated test tube, mix well, boil in a water bath for 5 minutes, then immediately take it out and cool to room temperature. Make up to 25mL with deionized water, mix well, and measure the absorbance of the color solution at a wavelength of 540mn. Use a mixture of 2mL of deionized water and 1.5mL of DNS reagent as a reference for zeroing. Calculate the reducing sugar content using the measured absorbance value and the standard curve, and the result is expressed in %.

[0077] Gas composition (%): The O2 concentration and CO2 concentration inside the package were measured and recorded using a Checkpoint-3 gas analyzer.

[0078] Color difference: CR-400 automatic colorimeter was used for colorimetry. 12 samples were randomly selected from each group. The equator of the fruit was selected. Each sample was measured 4 times. The L * 、a * , b * value.

[0079] Determination of DPPH and ABTS free radical scavenging ability: Purchase the DPPH and ABTS free radical scavenging activity kit from Beijing Solebow Technology Co., Ltd., and soak 1 cm biodegradable fresh-keeping bags or biodegradable curcumin fresh-keeping bags with the extract in the kit for 24 hours, and take the supernatant to determine the DPPH and ABTS free radical scavenging ability.

[0080] All the above indicators were measured in parallel.

[0081] The results are as follows (Note: Since the same batch of samples were used for the 0th day measurement, in order to facilitate the comparison of the changes in the fruit during storage, the 0th day measurement indicators of the same sample were selected. It is normal for the data to fluctuate during storage):

[0082] Depend on Figure 1 It can be seen that compared with Comparative Example 1, the degradable curcumin fresh-keeping bag obtained in Example 1 can inhibit the consumption of O2 and the increase of CO2 in the bag. On this basis, compared with Comparative Example 2 in which micropores are prepared, the degradable curcumin fresh-keeping bag obtained in Example 2 has the most obvious effect of inhibiting the decrease of O2 and the increase of CO2, and can maintain the "high O2 and low CO2" gas environment in the bag, which is beneficial to the preservation of fruits that are more sensitive to CO2. Figure 2It can be seen that compared with Comparative Example 1, the DPPH and ABTS free radical scavenging ability of the degradable curcumin fresh-keeping bag obtained in Example 1 is significantly enhanced.

[0083] Depend on Figure 4 It can be seen that compared with Comparative Example 1, the degradable curcumin fresh-keeping bag obtained in Example 1 can significantly inhibit the decay of cherries and extend the shelf life; compared with Comparative Example 2, the degradable curcumin fresh-keeping bag obtained in Example 2 can significantly inhibit the substantial increase in the decay rate of cherries and delay the rapid decay of cherries. The fresh-keeping effect of Example 2 is significantly better than that of Example 1, Comparative Example 2, and Comparative Example 1.

[0084] Depend on Figure 5 It can be seen that compared with Comparative Examples 1 and 2, the degradable curcumin fresh-keeping bag obtained in Example 1 can inhibit the brightness of cherry L * The decrease in value, a * The value of b * The decrease in the value can significantly inhibit the serious browning of the fruit caused by the "high CO2" environment in the bag, making the a of Example 1 * The value is significantly lower than that of Comparative Example 1 and Comparative Example 2. On this basis, the degradable curcumin fresh-keeping bag obtained in Example 2 can inhibit the browning of cherry fruit and maintain the brightness of the fruit skin significantly better than Comparative Example 1, Comparative Example 2 and Example 1.

[0085] The content of sugars and acids in fruits and vegetables can directly reflect the maturity and quality of fruits and vegetables. Figure 5 It can be seen that the degradable curcumin fresh-keeping bag obtained in Example 1 can delay the decline of titratable acid content, soluble solid content, and reducing sugar content, maintain the normal physiological function of cherry fruit, and thus extend its shelf life. Compared with Example 1 and Comparative Examples 1-2, the degradable curcumin fresh-keeping bag obtained in Example 2 has a better effect of inhibiting the decline of sugar and acid substances in cherry fruit.

[0086] Combination Figure 3 The changes of cherries during storage shown in the figure indicate that Example 2 using the microporous atmosphere control technology in combination with Example 1 can significantly inhibit the browning of cherry fruits, reduce the decay rate, delay the metabolism of sugar and acid substances, and extend the shelf life of cherries from 6 days to 12 days.

[0087] Depend on Figure 7 It can be seen that Example 3 can significantly inhibit the weight loss of apricot fruits compared to Comparative Example 3; at the same time, compared to Comparative Example 4, the degradable curcumin fresh-keeping bag obtained in Example 3 can well improve the large-scale decay of fruits and prolong the storage time of apricot fruits. Figure 8 It can be seen that Example 3, which uses the preservation method of the present invention, can maintain a good hardness of the apricot fruit when stored for 28 days, effectively delaying the softening of the apricot fruit, thereby maintaining a good sensory quality.

[0088] Depend on Fig. 9 It can be seen that the brightness loss rate of apricot fruit in Example 3 is slower than that in Comparative Examples 3 and 4, and there is no obvious browning. At the same time, the degradable curcumin fresh-keeping bag obtained in Example 3 can inhibit the increase of titratable acid content, delay the conversion of sugar substances, maintain the normal physiological function of apricot fruit, and thus prolong the shelf life.

[0089] Combination Figure 6 It can be seen that the present invention can inhibit the decay and weight loss of Semati apricots, improve the problem of fruit softening, and maintain the hardness of the fruit. At the same time, the color difference value shows that the degradable curcumin fresh-keeping bag obtained in Example 3 can effectively maintain the brightness of the peel, inhibit the occurrence of browning, and can also inhibit the decrease of titratable acid content, delay the increase of soluble solids and reducing sugars, maintain the sensory quality of apricots, and prolong the storage time.

[0090] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments, and it is not necessary and impossible to list all the embodiments here. For ordinary technicians in the relevant field, any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principle of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A method for preparing a curcumin fresh-keeping emulsion, characterized in that: The specific steps of the preparation method are as follows: (1) mixing curcumin and peony seed oil to obtain a mixed solution, stirring the mixed solution with a magnetic stirrer at 1200 rpm and 70° C. for 0.5 h to obtain a curcumin-peony seed oil mixed solution; (2) A 0.01-0.03 g / mL sodium carboxymethyl cellulose aqueous solution, a curing agent, a plasticizer, and a curcumin-peony seed oil mixture are stirred in a magnetic stirrer, homogenized, and ultrasonicated to obtain a curcumin fresh-keeping emulsion.

2. The preparation method according to claim 1, characterized in that: In the step (1), the mass ratio of curcumin to peony seed oil is 2:3; 1 w / w % of anhydrous ethanol is added to the mixed solution and then stirred; in the step (2), the plasticizer is glycerol, and the curing agent is Tween 80; the amount of the plasticizer added is 15 w / w %-20 w / w % of sodium carboxymethyl cellulose, and the amount of the curing agent added is 2 w / w %-5 w / w % of sodium carboxymethyl cellulose; the amount of the curcumin-peony seed oil mixed solution added is 20 w / w %-50 w / w % of sodium carboxymethyl cellulose.

3. The preparation method according to claim 1, characterized in that: The specific steps in step (2) are as follows: dissolving sodium carboxymethyl cellulose in deionized water, stirring with a magnetic stirrer at 1000 rpm for 2-5 hours until the sodium carboxymethyl cellulose is completely dissolved; adding a plasticizer to the sodium carboxymethyl cellulose solution, stirring at 1000 rpm for 0.5 hours; then adding a curing agent, stirring with a magnetic stirrer at 800 rpm for 0.25-1.5 hours until it is completely dissolved, adding a curcumin-peony seed oil mixture, stirring with a magnetic stirrer at 800 rpm for 0.5 hours, and obtaining a solution A; homogenizing the solution A with a homogenizer at 12000 rpm, and then letting it stand, and obtaining a curcumin fresh-keeping emulsion after ultrasonic treatment; the homogenization time of the solution A is 5-15 minutes, and the standing time is 2-5 minutes, preferably, the homogenization time is 8 minutes, and the standing time is 2 minutes; the ultrasonic treatment is to use a 15 nm ultrasonic probe for ultrasonic destruction, and the ultrasonication times are 10 times, each time for 60 seconds, and the interval time is 5 seconds.

4. The curcumin fresh-keeping emulsion obtained by the preparation method according to any one of claims 1 to 3.

5. Application of the curcumin fresh-keeping emulsion as claimed in claim 4 in a degradable fresh-keeping bag.

6. A method for preparing a degradable curcumin fresh-keeping bag, characterized in that: The preparation method specifically comprises the following steps: ① Evenly distribute the curcumin fresh-keeping emulsion on the inner side of the bottom seal of the biodegradable fresh-keeping bag; ② Place the sealed bottom end of the curcumin fresh-keeping emulsion in step ① on the scraper side of the coating machine, so that the degradable fresh-keeping bag can be extended as flatly as possible on the working surface of the coating machine, and use the vacuum adsorption function of the coating machine itself to make the degradable fresh-keeping bag be adsorbed flatly on the working surface; ③ Set the required coating thickness on the coating machine, and use the coating machine's scraper to slowly apply the curcumin fresh-keeping emulsion from the inner side of the bottom end of the seal of the degradable fresh-keeping bag to 1-2 cm away from the open end, and then control the coating machine scraper to run from 1-2 cm from the open end back to the bottom end of the seal, and apply it multiple times until the curcumin fresh-keeping emulsion is evenly distributed on the inner wall of the degradable fresh-keeping bag; ④ Place the evenly coated curcumin fresh-keeping bag in a drying environment at 55°C to dry, and obtain a degradable curcumin fresh-keeping bag.

7. The preparation method according to claim 6, characterized in that: In the step ③, the coating thickness of the curcumin fresh-keeping emulsion is 50-250 μm; and in the step ④, the drying time is 12h-30h.

8. The degradable curcumin fresh-keeping bag obtained by the preparation method as claimed in claim 6 or 7.

9. Use of the degradable curcumin fresh-keeping bag as claimed in claim 8 in preserving fruits and vegetables.

10. Application of the degradable curcumin fresh-keeping bag according to claim 9 in preserving fruits and vegetables, characterized in that: When the fruits and vegetables are CO2-resistant fruits and vegetables, the curcumin biodegradable fresh-keeping bag has one side coated with the fresh-keeping emulsion as the inner wall of the fresh-keeping bag, and the fruits and vegetables are directly packaged for use; When the fruits and vegetables are sensitive to CO2 concentration or are in the fresh logistics process, the curcumin degradable fresh-keeping bag is punched by laser technology to prepare curcumin degradable microporous modified atmosphere packaging; preferably, under an environment of 15°C-20°C, 35-45 curcumin degradable microporous modified atmosphere packages with a pore size of 150-250 μm are selected to be prepared; under an environment of -4°C-8°C, 15-25 curcumin degradable microporous modified atmosphere packages with a pore size of 100-200 μm are selected to be prepared.

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