Application of aconitic acid in inhibition of browning of fruits and / or vegetables and inhibition of microorganisms

Abstract

The invention discloses application of aconitic acid in inhibition of browning of fruits and / or vegetables and inhibition of microorganisms. The use method of the aconitic acid is simple, and the aconitic acid only needs to be added into fruit and vegetable pulp or prepared into an aconitic acid aqueous solution to be used for soaking fresh-cut fruits and vegetables which are cleaned, disinfected, peeled and cut. Experiments prove that aconitic acid can effectively inhibit browning of apple, potato and snow pear slurry, fresh-cut apple slices and shredded potatoes, maintain the original color and flavor of the apple, potato and snow pear slurry, fresh-cut apple slices and shredded potatoes, maintain the original flavor of fresh-cut cucumbers and inhibit the total number of bacterial colonies of fresh-cut fruits and vegetables; the medicine has the advantages of safe use and no toxic or side effect. The treatment method for inhibiting browning and microorganisms of the fresh-cut fruits and vegetables by using aconitic acid provided by the invention is simple, easy to operate and popularize, low in cost and suitable for large-scale production and use.

Description

Technical Field

[0001] The invention relates to the technical field of fruit and vegetable preservation, and in particular to application of aconitic acid in inhibiting browning of fruits and / or vegetables and inhibiting microorganisms. Background Art

[0002] With the development of society, in recent years, fresh-cut fruits and vegetables have attracted widespread attention from consumers due to their advantages such as health, freshness and convenience. In order to meet market demand, the fresh-cut fruit and vegetable industry has gradually shifted from quantity to quality. With the development of cold chain logistics and pre-prepared dishes, the demand for fresh-cut products has increased widely around the world, and the application of fresh-cut fruits and vegetables has gradually moved towards the catering industry and supermarket retail. How to extend the shelf life and supply chain length of fresh-cut products while ensuring the original flavor and nutrition of the products is a key issue of concern to the industry. Most fresh-cut fruits and vegetables are prone to enzymatic browning reactions due to the coexistence of polyphenol oxidase (PPO), phenolic substrates, and oxygen. At the same time, because fresh-cut products have a high water activity, they are prone to water loss, shrinkage, and the growth of microorganisms. At present, the types of fresh-cut fruits and vegetables are mainly apples, potatoes, eggplants, cabbages, onions, etc. In addition to being eaten or sold directly, some fruits and vegetables can be processed into products such as juice, and the above problems also need to be solved.

[0003] Fresh-cut apples are a ready-to-eat product that is convenient and fast, and are loved by people in a fast-paced society. However, compared with unprocessed apples, fresh-cut apples are more likely to deteriorate in quality during storage. Studies have shown that after fresh-cut apples, nutrients such as water and vitamins will flow out as cells rupture, reducing their taste and nutritional content. At the same time, after the cells are damaged, PPO combines with phenolic substances in apples, causing the surface of the apples to brown and lose their commodity value. Fresh-cut potatoes are one of the most in-demand types of fresh-cut fruit and vegetable products. As the world's fourth largest staple food after wheat, corn, and rice, the demand and quality requirements for potatoes in the fresh-cut industry are constantly increasing. Potatoes are very likely to brown after fresh-cutting, which is the main problem facing fresh-cut potatoes. After cucumbers are cut, they lose their epidermal tissue, and the loss of water and nutrients is aggravated, resulting in a shorter shelf life and a short low-temperature storage time. At the same time, during the storage process, corrupt microorganisms will destroy the organizational structure of fruits and vegetables through metabolic activities, produce volatile compounds with odors, and cause fruits and vegetables to spoil.

[0004] At present, the main technologies for controlling browning of fresh-cut fruits and vegetables are physical methods, chemical methods and biotechnology methods. Physical methods include controlled atmosphere preservation technology, ultra-high pressure technology, heat treatment technology, etc.; chemical methods mainly use ascorbic acid, citric acid, calcium chloride and other chemical inhibitors to inhibit browning; biotechnology mainly uses genetic engineering to modify the PPO gene of fruits and vegetables to reduce its expression, thereby inhibiting browning. The above methods can effectively inhibit the browning of fresh-cut fruits and vegetables, but the physical method has high requirements for equipment and technology, and it is difficult to meet the industrialization needs of small and medium-sized enterprises; although chemical technology has a good effect in inhibiting browning, it is costly and there may be problems with drug residues.

[0005] In addition to being sold directly in retail, fresh-cut fruits and vegetables can also be processed into fruit juice and vegetable juice. However, during the processing of fruit and vegetable juice, browning not only affects the appearance, but also its nutritional value and flavor. Taking pear juice as an example, because the PPO activity and phenolic content in pear fruit are particularly prominent, enzymatic browning is prone to occur during the processing of pear juice. Common physical methods such as high voltage and electric field processing have been applied to the juice processing industry abroad. At present, domestic research in this field needs to be further deepened. Among chemical additives, excessive addition may cause safety problems, and the color protection ability of a single substance is limited. The inhibitory effect on PPO of different varieties of fruits and vegetables is also different. Therefore, it is very important to develop green and healthy browning inhibitors from endogenous substances in fruits and vegetables themselves.

[0006] In summary, the fresh-cut fruit and vegetable industry still urgently needs to develop methods and technologies that are safe, green, inexpensive, have good browning inhibition, freshness preservation, and antibacterial effects, and are easy to industrialize and apply in fresh-cut apples, potatoes, cucumbers and other vegetables, as well as fruit and vegetable juice processing industries. Summary of the invention

[0007] In order to overcome the problems in the above-mentioned background technology, the purpose of the present invention is to provide the use of aconitic acid in inhibiting browning of fruits and / or vegetables and inhibiting microorganisms. The present invention verifies for the first time through experiments that aconitic acid can effectively maintain the inherent color of fresh-cut fruits and vegetables such as apple, potato and snow pear slurry, fresh-cut apples, potato shreds and cucumber slices, reduce their water loss, inhibit the total number of colonies, and extend the shelf life of fresh-cut fruits and vegetables. Moreover, the method has low economic cost, simple process, convenient operation, high food safety, and is easy to apply on a large scale.

[0008] To achieve the above object, the present invention adopts the following technical solutions:

[0009] The invention provides application of aconitic acid in inhibiting browning of fruits and / or vegetables and inhibiting microorganisms.

[0010] Furthermore, when fruits and / or vegetables are directly soaked in the aqueous solution of aconitic acid, the mass ratio concentration of the aqueous solution of aconitic acid is 4.0% to 10.0%.

[0011] Preferably, the aconitic acid is used at a concentration of 6.0%.

[0012] Furthermore, when the fruit and / or vegetable is in the form of slurry, the concentration of the aconitic acid in the slurry is 5 mg / mL to 50 mg / mL.

[0013] Furthermore, the soaking temperature of the aconitic acid aqueous solution is 10°C to 25°C.

[0014] Preferably, the temperature of the aconitic acid solution is 16-25°C.

[0015] Furthermore, the immersion time of the aconitic acid aqueous solution is 1 min to 5 min.

[0016] Preferably, the aconitic acid aqueous solution is used to soak fruits for 5 minutes and vegetables for 1 minute.

[0017] Furthermore, the fruits are apples and pears; the vegetables are potatoes and cucumbers.

[0018] Furthermore, the application method for inhibiting browning and microorganisms of fruits and / or vegetables comprises the following steps: washing the fruits and / or vegetables, peeling them, and sterilizing them to prepare peeled fruits and / or peeled vegetables, or cutting the peeled fruits and / or peeled vegetables into slices, or grating them into shreds, and then soaking them in the aqueous solution of aconitic acid or a preservative containing aconitic acid at 16° C. for 1 min to 5 min, draining the water, packing them in boxes, and storing them at low temperature.

[0019] Furthermore, the fruits and / or vegetables are freshly harvested or stored fruits and / or vegetables.

[0020] Furthermore, the apples and potatoes were cleaned, peeled, and disinfected, and the apples were not peeled and cut into 12 pieces; the potatoes were peeled and cut into 2 mm thin slices longitudinally or grated into 2 mm × 2 mm shreds with a width / thickness ratio; the cucumbers were cleaned and disinfected and cut into 2 cm thick slices, and soaked in a 6.0% aconitic acid aqueous solution or a preservative containing 6.0% aconitic acid at 16 ℃ for 5 min, 1 min, and 1 min, respectively, and then packed in boxes after draining the water and stored at 4 ℃.

[0021] The invention also provides a preservative containing aconitic acid for inhibiting browning of fruits and / or vegetables.

[0022] Furthermore, the preservative contains aconitic acid at a concentration of 4.0% to 10.0% as an effective ingredient.

[0023] Preferably, the preservative contains aconitic acid at a concentration of 6.0% as an active ingredient.

[0024] Compared with the prior art, the present invention has the following advantages and beneficial technical effects:

[0025] The present invention verifies for the first time through experiments that aconitic acid has the effect of inhibiting the browning of apple juice, pear juice, fresh-cut apples and potato shreds, and the effect of keeping fresh-cut apples, potato shreds and cucumber slices fresh and inhibiting bacteria, and the method of use is simple, and a treatment method for inhibiting the browning of fresh-cut apples and potato shreds is developed accordingly, which has the following advantages:

[0026] (1) Significant technical effect: It can effectively maintain the inherent color of fruit and vegetable juice, fresh-cut apple slices and potato shreds, and prevent water loss and browning. It has a fresh-keeping effect on fresh-cut apples, potato shreds and cucumber slices, and can inhibit their total bacterial count.

[0027] (2) Healthy and environmentally friendly: Aconitic acid is a green food additive that can be used in food production. It is safe and harmless, and its application in improving the quality of fresh-cut fruits and vegetables does not pose any food safety issues.

[0028] (3) Simple method: The method of the present invention for inhibiting the browning of apple juice, pear juice, fresh-cut apple slices and potato shreds and maintaining the quality of fresh-cut apples, potato shreds and fresh-cut cucumbers, and inhibiting microorganisms has simple steps, is easy to operate and promote in factories, and is suitable for large-scale production and processing.

[0029] (4) Economical and applicable: Aconitic acid currently has a mature production process with low cost. Its use in juice and fresh-cut fruits and vegetables will not increase its cost and is economical and applicable. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Effects of different concentrations of aconitic acid aqueous solution on the browning of fresh-cut apple pulp.

[0031] Figure 2 This paper shows the effect of 6% aconitic acid aqueous solution treated at different temperatures for 5 min on the browning of fresh-cut apple slices.

[0032] Figure 3 Effects of different concentrations of aconitic acid aqueous solution treated at 16 ℃ for 5 min on the browning of fresh-cut apple slices.

[0033] Figure 4 This paper studies the effect of 6.0% aconitic acid aqueous solution at 16 ℃ for different time periods on the browning of fresh-cut apple slices.

[0034] Figure 5 This paper shows the effect of different concentrations of aconitic acid aqueous solution on the browning of fresh-cut potato pulp.

[0035] Figure 6 This paper shows the effect of 6% aconitic acid aqueous solution treated at different temperatures for 5 min on the browning of fresh-cut potato shreds.

[0036] Figure 7 This study shows the effect of different concentrations of aconitic acid aqueous solution treated at 16 ℃ for 5 min on the browning of fresh-cut potato shreds.

[0037] Figure 8 This paper studies the effect of 6.0% aconitic acid aqueous solution at 16 ℃ for different time periods on the browning of fresh-cut potato shreds.

[0038] Fig. 9 This is the effect of different concentrations of aconitic acid aqueous solution on the browning of snow pear pulp.

[0039] Fig.10 This is the effect of 6.0% aconitic acid aqueous solution treated at 16 ℃ for 5 min on the total colony count of fresh-cut apples.

[0040] Fig.11 The effect of 6.0% aconitic acid aqueous solution at 16 ℃ for 1 min on the total bacterial count of fresh-cut potato threads.

[0041] Fig.12 This paper shows the effect of 6.0% aconitic acid aqueous solution treated at 16 ℃ for 1 min on the total colony count of fresh-cut cucumbers. DETAILED DESCRIPTION

[0042] The technical solution of the present invention is further described in detail with reference to the following specific examples. In the following examples, unless otherwise specified, the experimental methods used are conventional methods, and the materials and reagents used can be purchased from biological or chemical reagent companies.

[0043] The present invention provides a method for inhibiting browning of fresh-cut apples and potatoes and preserving fresh-cut apples, potato shreds and cucumber slices, and inhibiting the total number of bacterial colonies, comprising the following steps:

[0044] (1) Cleaning: Wash the apples, potatoes and cucumbers with tap water to remove surface dirt, impurities, etc.;

[0045] (2) Disinfection: Use non-toxic disinfectant aqueous solutions such as sodium hypochlorite, hydrogen peroxide, and ozone to disinfect the surfaces of apples, potatoes, and cucumbers;

[0046] (3) Peeling: Use a peeler to peel the skin of the washed potatoes. Apples and cucumbers do not need to be peeled.

[0047] (4) Cutting: Use a sterile cutting board and an apple cutter to cut the sterilized apples into 12 pieces.

[0048] (5) Shredding: Use a sterile potato shredder to grate the sterilized peeled potatoes into shreds with a width / thickness ratio of 2 mm × 2 mm;

[0049] (6) Slicing: Use a sterile cutting board and kitchen knife to cut the sterilized cucumber into 1-2 cm thick slices;

[0050] (7) Soaking: Soak apple slices and potato shreds in an aqueous solution of aconitic acid;

[0051] (8) Draining: Use sterile gauze to absorb the moisture on the surface of the apple slices; use a spin dryer to spin the solution in the soaked potato shreds for 3-5 seconds;

[0052] (9) Packaging: Put the drained apple slices and potato shreds into a fresh-keeping box;

[0053] (10) Low temperature storage: Store the packaged apple slices and potato shreds in a cold storage at 2-4°C.

[0054] The present invention has experimentally determined that the temperature, concentration and soaking time of the aconitic acid aqueous solution used for soaking apple slices and potato shreds are key factors affecting the browning inhibition effect of fresh-cut apple slices and potato shreds. Only by using an aconitic acid aqueous solution with a suitable concentration and temperature for soaking for a suitable time can browning be effectively inhibited and good quality be maintained.

[0055] The present invention has been proved by the following experiments that the use of an aqueous solution of aconitic acid at a temperature of 10-25°C to treat apple slices and potato shreds can effectively inhibit the browning and water loss of the cut surfaces of apples and potatoes.

[0056] The apple slices and potato shreds were soaked in a 6.0% aconitic acid aqueous solution, which had a better effect on inhibiting the browning of fresh-cut apples and potatoes.

[0057] In addition, the soaking time will also affect the inhibitory effect on the browning of fresh-cut apple slices and potato shreds. If the soaking time is too short, the inhibitory effect on the browning of fresh-cut apple slices and potato shreds is not significant; if the soaking time is too long, the starch, polyphenols and other nutrients of the apples and potatoes themselves will be washed away during the soaking process, which is not conducive to maintaining the nutritional quality of the apples and potatoes in the later stage; the experimental results of the present invention show that the soaking time is preferably 1 to 5 minutes.

[0058] The following examples will optimize the treatment process of soaking snow pear slurry, fresh-cut apple slurry and potato slurry with aconitic acid and put the optimal results into practice on fresh-cut apple slices, fresh-cut potato shreds and fresh-cut cucumber slices.

[0059] Example 1: Concentration optimization of aconitic acid-treated fresh-cut apple slurry

[0060] 8 portions of 1 g apple jelly powder were weighed, 7 of which were added with 3 mL of 5 mg / mL, 10 mg / mL, 20 mg / mL, 30 mg / mL, 40 mg / mL, and 50 mg / mL aconitic acid solution and 3 mL of 0.8 mg / mL cysteine, and the remaining 1 was added with 3 mL of deionized water as a control. The color changes were observed and photographed at 0 h, 2 h, 4 h, 6 h, 12 h, and 24 h, and the L value was determined.

[0061] After the fresh-cut apple pulp of the control group and each aconitic acid group was stored in the same environment for 24 h, the browning inhibition effect and L value of the fresh-cut apple pulp treated with different concentrations of aconitic acid aqueous solution were analyzed. Figure 1 As shown in the figure, the control group had already browned severely after 2 hours of storage, while the browning degree of the apples treated with 10 mg / mL and 20 mg / mL aconitic acid aqueous solution was significantly lower than that of the control group, and the browning degree of the apples treated with 30 mg / mL, 40 mg / mL, and 50 mg / mL aconitic acid aqueous solution was significantly lower than that of the cysteine ​​treatment group. Moreover, 50 mg / mL aconitic acid can significantly inhibit the browning of apple pulp, and the inhibitory effect can last up to 24 hours. The L value of apple pulp was measured and it was found that at 24 hours, the L value of apple pulp treated with 30 mg / mL, 40 mg / mL, and 50 mg / mL aconitic acid aqueous solution was significantly higher than that of the CK group and the cysteine ​​treatment group, which is consistent with the results shown in the apple pulp picture.

[0062] Example 2: Optimization of soaking temperature for fresh-cut apple slices treated with aconitic acid

[0063] After the apples were washed, disinfected, peeled and cut into pieces, the apple slices were soaked in a 6.0% aconitic acid aqueous solution at 10 ℃, 16 ℃ and 25 ℃ respectively for 5 min. After draining the water, they were put into fresh-keeping boxes and stored in a cold storage at 2-4 ℃.

[0064] Clean water control group: After the apples of the same variety and batch were washed, disinfected, peeled and cut into pieces, the apple slices were soaked in clean water at 10 ℃, 16 ℃ and 25 ℃ respectively (soaked at the same time as the aconitic acid group) for 5 min, put into fresh-keeping boxes, and stored in a cold storage at 2-4 ℃.

[0065] The fresh-cut apple slices in the water control group and the aconitic acid group were stored in the same cold storage at 2-4 ℃ for 7 days. The browning inhibition effect of the fresh-cut apple slices soaked in aconitic acid aqueous solution at different temperatures was as follows: Figure 2The L value is shown in Table 1. The aconitic acid solutions at different temperatures have similar inhibitory effects on the browning of fresh-cut apple slices, with no significant difference. The natural water temperature in summer and autumn is around 25 °C, and the natural water temperature in winter and spring is around 16 °C. In actual production, the water temperature does not need to be adjusted in different seasons and weather to meet the needs.

[0066] Table 1. L values ​​of fresh-cut apples treated with aconitic acid at different temperatures after storage for 0 and 7 days

[0067] Note: Different letters indicate significant differences between different treatment temperatures in the same treatment group (p<0.05).

[0068] Example 3: Concentration optimization of aconitic acid treatment of fresh-cut apple slices

[0069] After the apples were washed, disinfected, peeled, and cut into pieces, the apple slices were soaked in aqueous solutions of aconitic acid of different concentrations (5.0%, 6.0%, 8.0%, and 10.0%) at 16 ℃ for 5 min. After draining the water, they were packed into fresh-keeping boxes and stored in a cold storage at 2-4 ℃.

[0070] A control group (CK) was set up: apples of the same variety and batch were washed, disinfected, peeled, cut into pieces, placed at room temperature for 5 min without any soaking treatment, put into fresh-keeping boxes, and stored in a cold storage at 2-4 ℃.

[0071] Clean water group: After washing, disinfecting, peeling and cutting apples of the same variety and batch, the apple slices were soaked in clean water (immersed at the same time as the aconitic acid group) at 16 ℃ for 5 min, put into fresh-keeping boxes, and stored in a cold storage at 2-4 ℃.

[0072] The fresh-cut apple slices in the control group, water group and various aconitic acid groups were stored in the same cold storage at 2-4 ℃ for 12 days. The browning inhibition effects of the fresh-cut apple slices treated with aconitic acid aqueous solution of different concentrations were as follows: Figure 3 The L value is shown in Table 2. The control group had serious browning on the first day of storage, and on the third day, it lost water and browned seriously, losing its commercial value; the water group had a dull color on the third day, and its quality was seriously reduced; after being soaked in 5.0%~10.0% aconitic acid solution, the browning degree was significantly lower than that of the control group and the water group, and the apple slices treated with 6.0% aconitic acid basically did not brown after 12 days of storage, and the L value was significantly higher than that of the CK group and the water treatment group.

[0073] Table 2. L values ​​of fresh-cut apples treated with different concentrations of aconitic acid at 0 and 12 days of storage

[0074]

[0075] Note: Different letters indicate significant differences among different treatment groups (p<0.05).

[0076] Example 4: Optimization of soaking time for fresh-cut apple slices treated with aconitic acid

[0077] After the apples were washed, disinfected, peeled and cut into pieces, the apple slices were soaked in a 6.0% aconitic acid aqueous solution at 16 ℃ for different time periods (1 min, 3 min, and 5 min). After draining the water, they were put into fresh-keeping boxes and stored in a cold storage at 2-4 ℃.

[0078] A control group (CK) was set up: apples of the same variety and batch were washed, disinfected, peeled, and cut into pieces. Without any soaking treatment, they were placed at room temperature for different time periods (1 min, 3 min, and 5 min), put into fresh-keeping boxes, and stored in a cold storage at 2-4 ℃.

[0079] Clean water group: After washing, disinfecting, peeling and cutting apples of the same variety and batch, the apple slices were soaked in clean water at 16 ℃ (immersed at the same time as the aconitic acid group) for different soaking times (1 min, 3 min, 5 min), drained and packed into fresh-keeping boxes, and stored in a cold storage at 2-4 ℃.

[0080] After the fresh-cut apple slices in the control group, water group and each aconitic acid group were stored in a cold storage at 2-4 ℃ for 12 days, the inhibitory effect of aconitic acid aqueous solution on the browning of fresh-cut apple slices at different soaking times was as follows: Figure 4 As shown in Table 3, the control group had browning on day 1 and lost its commodity value on day 3; the water group had severe water loss on day 3, and its quality was seriously reduced, and it completely lost its commodity value on day 5; and the browning was significantly reduced after soaking in 6.0% aconitic acid solution for 1 min, 3 min, and 5 min, and the L values ​​were significantly higher than those of the CK group and the water treatment group, and the effects were comparable. In actual production, considering the time cost, soaking for 1 min can be preferred to meet the needs.

[0081] Table 3. L values ​​of fresh-cut apples treated with 6.0% aconitic acid for different storage times at 0 and 12 days

[0082]

[0083] Note: Different capital letters indicate significant differences among different treatment groups at the same treatment time (p<0.05); Different lowercase letters indicate significant differences among different treatment times in the same treatment group (p<0.05).

[0084] Example 5: Concentration Optimization of Aconitic Acid-treated Fresh-cut Potato Slurry

[0085] Weigh 8 portions of 1 g potato jelly, add 3 mL of aconitic acid solution and 3 mL of cysteine ​​with concentrations of 5 mg / mL, 10 mg / mL, 20 mg / mL, 30 mg / mL, 40 mg / mL, and 50 mg / mL, respectively, to 7 of them, and add 3 mL of deionized water to the remaining portion as a control. Observe the color changes, take photos, and determine the L value at 0 h, 2 h, 4 h, 6 h, 12 h, and 24 h.

[0086] After the fresh-cut potato slurries of the control group and each aconitic acid group were stored in the same environment for 24 h, the browning inhibition effect and L value of the fresh-cut potato slurries treated with different concentrations of aconitic acid aqueous solution were shown in Figure 2. Figure 5 As shown in the figure, the control group had browned severely at 2 hours of storage and turned completely black at 12 hours. After treatment with 10 mg / mL and 20 mg / mL aconitic acid aqueous solution, the browning degree was significantly lower than that of the control group. After treatment with 30 mg / mL, 40 mg / mL, and 50 mg / mL aconitic acid aqueous solution, the browning degree was significantly lower than that of the cysteine ​​treatment group. Cysteine ​​has been reported to inhibit the browning of fresh-cut potatoes, and 50 mg / mL aconitic acid can significantly inhibit the browning of potato pulp, and the inhibitory effect can last up to 24 hours. After 24 hours of storage, the L value of potato pulp in the 20 mg / mL, 30 mg / mL, 40 mg / mL, and 50 mg / mL aconitic acid aqueous solution treatment groups was significantly higher than that of the CK group and the cysteine ​​treatment group, which is consistent with the results shown in the potato pulp picture.

[0087] Example 6: Optimization of soaking temperature for fresh-cut potato shreds treated with aconitic acid

[0088] After washing, disinfecting, peeling and grating the potatoes (width / thickness ratio is 2 mm×2 mm), soak the shredded potatoes in a 6.0% aconitic acid aqueous solution at 10℃, 16℃ and 25℃ for 5 min. After draining the water, put them into a fresh-keeping box and store them in a cold storage at 2-4℃.

[0089] Clean water control group: potatoes of the same variety and batch were washed, disinfected, peeled, and shredded, then soaked in clean water at 10 ℃, 16 ℃, and 25 ℃ (soaked at the same time as the aconitic acid group) for 5 min, drained, put into fresh-keeping boxes, and stored in a cold storage at 2-4 ℃.

[0090] After the fresh-cut potato shreds in the water group and the aconitic acid group were stored in the same cold storage at 2-4 ℃ for 7 days, the browning inhibition effect of the fresh-cut potato shreds treated with aconitic acid aqueous solution at different temperatures was as follows: Figure 6The results of L value are shown in Table 4. At 7 days, the inhibitory effects of aconitic acid solutions at different temperatures on the browning of fresh-cut potato shreds were comparable, with no significant difference. The natural water temperature in summer and autumn is around 25 °C, and the natural water temperature in winter and spring is around 16 °C. In actual production, the water temperature does not need to be adjusted in different seasons and weather to meet the needs.

[0091] Table 4. L values ​​of fresh-cut potato shreds treated with aconitic acid at different temperatures after storage for 0 and 7 days

[0092]

[0093] Note: Different letters indicate significant differences between different treatment temperatures in the same treatment group (p<0.05).

[0094] Example 7: Optimization of the concentration of aconitic acid in treating fresh-cut potato shreds

[0095] After washing, disinfecting, peeling and grating the potatoes (width / thickness ratio of 2 mm×2 mm), the shredded potatoes were immersed in aqueous solutions of aconitic acid of different concentrations (4.0%, 6.0%, 10.0%) at 16 ℃ for 5 min. After draining the water, the shredded potatoes were packed into fresh-keeping boxes and stored in a cold storage at 2-4 ℃.

[0096] A control group (CK) was set up: potatoes of the same variety and batch were washed, disinfected, peeled, and grated without any soaking treatment. They were placed at room temperature for 5 min, put into fresh-keeping boxes, and stored in a cold storage at 2-4 ℃.

[0097] Clean water group: potatoes of the same variety and batch were washed, disinfected, peeled, and shredded, then soaked in clean water (soaked at the same time as the aconitic acid group) at 16 ℃ for 5 min. After draining the water, they were packed into fresh-keeping boxes and stored in a cold storage at 2-4 ℃.

[0098] After the fresh-cut potato shreds in the control group, water group and various aconitic acid groups were stored in the same cold storage at 2-4 ℃ for 7 days, the inhibitory effects of soaking in different concentrations of aconitic acid aqueous solution on the browning of fresh-cut potato shreds were as follows: Figure 7 As shown in Table 5, the control group had serious browning and black color after 1 day of storage, and lost its commercial value; the water group had serious water loss and serious quality reduction after 3 days of storage; and after soaking in 4.0%~10.0% aconitic acid solution, the browning degree was significantly lower than that of the control group and the water group, and the potato shreds treated with 6.0% aconitic acid basically did not brown after 7 days of storage. The L value results are shown in Table 5. At 7 days, the L values ​​of the treatment groups were significantly higher than those of the CK group and the water treatment, and the L value of the 6.0% aconitic acid treatment group was the highest.

[0099] Table 5. L values ​​of fresh-cut potato shreds treated with different concentrations of aconitic acid at 0 and 7 days of storage

[0100]

[0101] Note: Different letters indicate significant differences among different treatment groups (p<0.05).

[0102] Example 8: Optimization of soaking time for fresh-cut potato shreds treated with aconitic acid

[0103] After washing, disinfecting, peeling and shredding (width / thickness ratio of 2 mm×2 mm), the potatoes were soaked in a 6.0% aconitic acid aqueous solution at 16°C for different time periods (1 min, 3 min, and 5 min). After draining the water, they were packed into fresh-keeping boxes and stored in a cold storage at 2-4°C.

[0104] A control group (CK) was set up: potatoes of the same variety and batch were washed, disinfected, peeled, and grated without any soaking treatment. They were placed at 16 ℃ for different time periods (1 min, 3 min, and 5 min), put into fresh-keeping boxes, and stored in a cold storage at 2-4 ℃.

[0105] Clean water group: potatoes of the same variety and batch were washed, disinfected, peeled, and shredded, then soaked in clean water at 16°C (soaked at the same time as the aconitic acid group) for different time periods (1 min, 3 min, and 5 min). After draining the water, they were packed into fresh-keeping boxes and stored in a cold storage at 2-4°C.

[0106] After the fresh-cut potato shreds in the control group, water group and each aconitic acid group were stored in a cold storage at 2-4 ℃ for 9 days, the inhibitory effect of aconitic acid aqueous solution on the browning of fresh-cut potato shreds at different soaking times was as follows: Figure 8 As shown in Table 6, the control group turned black and brown after 1 day, losing its commercial value; the water group lost water seriously after 2 days of storage, and the quality was seriously reduced; and the browning was significantly reduced after soaking in 6.0% aconitic acid solution for 1 min, 3 min, and 5 min. The L value after 9 days of storage is shown in Table 6. Although the L value of potato shreds treated with 5 min soaking for 9 days is the highest, combined with Figure 6 Analysis showed that soaking for 5 min would cause potato shreds to turn white and lose their original color. Therefore, soaking in 6.0% aconitic acid for 1 min was preferred for potato shreds.

[0107] Table 6. L values ​​of fresh-cut potato shreds treated with 6.0% aconitic acid for different storage times at 0 and 9 days

[0108]

[0109] Note: Different capital letters indicate significant differences among different treatment groups at the same treatment time (p<0.05); Different lowercase letters indicate significant differences among different treatment times in the same treatment group (p<0.05).

[0110] Example 9: Concentration Optimization of Aconitic Acid-treated Snow Pear Slurry

[0111] Weigh 8 portions of 1 g of snow pear jelly powder, add 3 mL of aconitic acid solution and 3 mL of cysteine ​​with concentrations of 3 mg / mL, 5 mg / mL, 10 mg / mL, 20 mg / mL, 30 mg / mL, and 40 mg / mL, respectively, to 7 of them, and add 3 mL of deionized water to the remaining 1 portion as a control. Observe the color change, take pictures, and determine the L value at 0 h, 2 h, 4 h, 6 h, 12 h, and 24 h.

[0112] After the pear pulp of the control group and each aconitic acid group was stored in the same environment for 24 h, the browning inhibition effect and L value of the pear pulp treated with different concentrations of aconitic acid aqueous solution were shown in the following table. Fig. 9 As shown in the figure, the control group had already browned severely after 2 h of storage, while the browning degree of the 5 mg / mL and 10 mg / mL aconitic acid aqueous solution treatment was significantly lower than that of the control group, and the browning degree of the 20 mg / mL, 30 mg / mL, and 40 mg / mL aconitic acid aqueous solution treatment was significantly lower than that of the cysteine ​​treatment group, and the 20 mg / mL aconitic acid aqueous solution could significantly inhibit the browning of the snow pear slurry, and the inhibitory effect could last for 24 h. After 24 h of storage, the L value of the snow pear slurry in the 20 mg / mL, 30 mg / mL, and 40 mg / mL aconitic acid treatment groups was significantly higher than that in the CK group and the cysteine ​​treatment group, which is consistent with the results shown in the snow pear slurry picture.

[0113] Example 10: Antibacterial effect of aconitic acid treatment on fresh-cut apples

[0114] Ten apples were selected and cut in a sterile operating table after cleaning and disinfection. Each apple was divided into 12 pieces, a total of 120 pieces, and divided into three groups: CK group, water treatment group and 6.0% aconitic acid treatment group. The samples in the CK group were directly put into sealed bags without any treatment. The fresh-cut apples in the water treatment group and the aconitic acid treatment group were soaked in sterile water and sterile aconitic acid solution for 5 min, respectively, and then put into sealed bags. The above fresh-cut apples were stored at 4 ℃. At 0 d, 7 d, and 12 d, 6-10 fresh-cut apples were taken from each group, and a total of 25 g of apple cross-section samples were cut and placed in 225 mL of sterile saline (0.9%) for extraction. The extract was diluted according to the standard method of gradient dilution in the national standard (GB 4789.2-2022), and 10 were taken respectively. -1 , 10 -3 , 10-5 , 10 -7 1 mL of each dilution was evenly spread on plate count agar (PCA) solid medium and incubated upside down at 37 °C for 48 h. The total number of colonies was counted and photographed. The results were as follows: Fig.10 As shown:

[0115] During the low-temperature storage of fresh-cut apples, the total number of colonies in the CK group, water treatment group and 6.0% aconitic acid treatment group increased with the increase of storage time. No microorganisms were detected in the 6% aconitic acid treatment group within 7 days of storage. Although there was an increase after 12 days of storage, the total number was as low as 2.5 lg CFU / g, which still had a good commodity value.

[0116] Example 11: Antibacterial effect of aconitic acid treatment on fresh-cut potato shreds

[0117] Five potatoes were selected and cleaned and disinfected, then grated in a sterile operating table and divided into three groups: CK group, water treatment group, and 6.0% aconitic acid treatment group. The samples in the CK group were directly put into sealed bags without any treatment. The potato shreds in the water treatment group and the aconitic acid treatment group were soaked in sterile water and sterile aconitic acid solution for 1 min, respectively, and then put into sealed bags. The above-mentioned fresh-cut potato shreds were stored at 4 ℃. At 9 days, 25 g of fresh-cut potato shreds were taken and placed in 225 mL of sterile saline (0.9%) for extraction. The extract was diluted according to the standard method of gradient dilution in the national standard (GB 4789.2-2022), and 10 -1 , 10 -3 , 10 -5 , 10 -7 1 mL of each dilution was evenly spread on plate count agar (PCA) solid medium and incubated upside down at 37 °C for 48 h. The total number of colonies was counted and photographed. Fig.11 As shown: During the low-temperature storage of fresh-cut potato shreds, no microorganisms were detected in the 6% aconitic acid treated group within 9 days of storage, and the potato shreds still had a good commercial value.

[0118] Example 12: Fresh-keeping and antibacterial effects of aconitic acid treatment on fresh-cut cucumbers

[0119] Ten cucumbers were selected and sliced ​​in a sterile operating table after cleaning and disinfection. Each cucumber was cut into 15 slices, a total of 150 slices, and divided into 3 groups: CK group, water treatment group, and 6.0% aconitic acid treatment group. The samples in the CK group were directly put into sealed bags without any treatment. The cucumber slices in the water treatment group and the aconitic acid treatment group were soaked in sterile water and sterile aconitic acid solution for 1 min, respectively, and then put into sealed bags. The above fresh-cut cucumber slices were stored at 4 ℃. At 4 days, 15-20 pieces of fresh-cut cucumbers were taken from each group, and a total of 25 g of cucumber cross-section samples were cut and placed in 225 mL of sterile saline (0.9%) for extraction. The extract was diluted according to the standard method of gradient dilution in the national standard (GB 4789.2-2022), and 10 were taken respectively. -1 , 10 -3 , 10 -5 , 10 -7 1 mL of each dilution was evenly spread on plate count agar (PCA) solid medium and incubated upside down at 37 °C for 48 h. The total number of colonies was counted and photographed. Fig.12 As shown: During the low-temperature storage of fresh-cut cucumbers, the total colony count of the 6% aconitic acid treatment group was significantly lower than that of the CK group and the water treatment group within 4 days, with a total count as low as 2.4 lg CFU / g, and still had a good commercial value.

[0120] The present invention proves through experiments that exogenous treatment of apple pulp and fresh-cut apples with aconitic acid can significantly inhibit browning, and there is no report on the application of aconitic acid in browning of fruits and vegetables. Aconitic acid (C6H6O6) is an unsaturated tricarboxylic acid. In the body, aconitic acid is an intermediate product of citric acid isomerized to isocitrate under the action of aconitase (located in mitochondria). Aconitic acid is a food additive allowed for use by the Joint Expert Committee on Food Additives (JECFA) under the Food and Agriculture Organization of the United Nations and the World Health Organization.

[0121] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for a person skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to replace some of the technical features therein by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions claimed to be protected by the present invention.

Claims

1. Application of aconitic acid in inhibiting browning of fruits and / or vegetables and inhibiting microorganisms.

2. The use according to claim 1, characterized in that: When fruits and / or vegetables are directly soaked in the aqueous solution of aconitic acid, the mass ratio concentration of the aqueous solution of aconitic acid is 4.0% to 10.0%.

3. The use according to claim 1, characterized in that: When the fruit and / or vegetable is in the form of slurry, the concentration of aconitic acid in the slurry is 5 mg / mL to 50 mg / mL.

4. The use according to claim 2, characterized in that: The soaking temperature of the aconitic acid aqueous solution is 10-25°C.

5. The use according to claim 2, characterized in that: The soaking time of the aconitic acid aqueous solution is 1 min to 5 min.

6. The use according to claim 1, characterized in that: The fruits are apples and pears; the vegetables are potatoes and cucumbers.

7. The use according to claim 1, characterized in that: The application method for inhibiting browning and microorganisms of fruits and / or vegetables comprises the following steps: washing the fruits and / or vegetables, peeling them, and sterilizing them to prepare peeled fruits and / or peeled vegetables, or cutting the peeled fruits and / or peeled vegetables into slices, or grating them, and then soaking them at 16°C for 1 min to 5 min using the aqueous solution of aconitic acid or a preservative containing aconitic acid described in claim 2, and then draining the water, packing them in boxes, and storing them at low temperature.

8. The use according to claim 7, characterized in that: The fruits and / or vegetables are freshly harvested or stored fruits and / or vegetables.

9. A preservative, characterized in that: The preservative contains aconitic acid, which is used for inhibiting the browning of fruits and / or vegetables, inhibiting the growth of microorganisms and having a good preservative effect.

10. The preservative according to claim 9, characterized in that: The preservative has aconitic acid in a mass ratio concentration of 4.0% to 10.0% as an effective preservative.

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