Application of pyroglutamic acid in fresh-cut fruit and vegetable preservation, browning resistance and bacteriostasis

Abstract

The application belongs to the technical field of food preparation, and particularly relates to application of pyroglutamic acid in fresh-cut fruit and vegetable preservation, browning resistance and bacterium inhibition. Fresh-cut fruit and vegetable are treated by the method, so that the browning degree of fresh-cut potato, lettuce, lotus root slice and other products during a shelf life is significantly delayed, the growth of microorganisms during the shelf life of the products is reduced, and the shelf life is prolonged. The anti-browning and bacterium-inhibiting preservative for fresh-cut fruit and vegetable provided by the application is safe, efficient and environmentally friendly.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of food preparation, and particularly relates to application of pyroglutamic acid in fresh-cut fruit and vegetable preservation, browning resistance and bacteriostasis. BACKGROUND

[0002] With the acceleration of modern life pace and the concern for life quality, people's consumption mode is changing, and the public demand for fresh, nutritious, safe and convenient food is increasing. Fresh-cut fruit and vegetable is a kind of food which takes fresh fruits and vegetables as raw materials, and is processed through a series of pretreatment, peeling, cutting, cleaning, surface water removal, sealing and packaging, and then is sold through cold chain storage and transportation. Fresh-cut fruit and vegetable is also a kind of ready-to-prepare pre-prepared vegetable product, which can be directly consumed by consumers or used by catering industry, such as fresh-cut potato, fresh-cut lettuce, fresh-cut lotus root and fresh-cut apple. Fresh-cut fruit and vegetable is prone to discoloration and corruption due to cell damage caused by cutting, which seriously affects the product quality and safety.

[0003] The existing fresh-cut fruit and vegetable preservation and bacteriostasis method mainly uses some chemical preservatives and bactericides to treat the product, including the commonly used hypochlorous acid-containing cleaning agent and sulfur-containing preservative color protection agent. Such preservatives and bactericides are reported to have certain safety hazards, and excessive use is not conducive to human health. Therefore, it is of important commercial value to develop safer, more efficient and environmentally friendly preservatives and bactericides to solve the problems of browning and microbial corruption of fresh-cut fruit and vegetable products during the flow process. Pyroglutamic acid is a natural organic acid derived from plant body, which is safe and has good development and application prospect. SUMMARY

[0004] The purpose of the present application is to provide application of pyroglutamic acid in fresh-cut fruit and vegetable preservation, browning resistance and bacteriostasis in view of the problems in the prior art. Pyroglutamic acid is prepared into a pyroglutamic acid solution with a certain concentration, which is then used in the processing of fresh-cut fruit and vegetable products, so as to produce good preservation, browning resistance and bacteriostasis functions on the fresh-cut fruit and vegetable products, thereby improving the quality and edible safety of the fresh-cut products and prolonging the shelf life of the products.

[0005] In order to achieve the above purpose, the specific technical scheme of the present application is as follows:

[0006] Application of pyroglutamic acid as the only or main active component in fresh-cut fruit and vegetable preservatives. For example, pyroglutamic acid can be dissolved in water or other solvents to prepare a fresh-cut fruit and vegetable preservative, and the concentration of pyroglutamic acid in the preservative is preferably 0.1 g / L-3.5 g / L.

[0007] As a better embodiment in the present application, the following steps are included:

[0008] The fresh-cut fruits and vegetables are washed, peeled and cut, and then placed in water for standby; then put into the preservative for soaking, and after being taken out and dried, packaged and stored at low temperature.

[0009] Pyroglutamic acid is used as the only or main active component in the fresh-cut fruits and vegetables anti-browning agent. For example, pyroglutamic acid can be dissolved in water or other solvents to prepare the fresh-cut fruits and vegetables anti-browning agent, preferably the concentration of pyroglutamic acid in the anti-browning agent is 0.1g / L-3.5g / L.

[0010] As a preferred embodiment in the present application, the following steps are included:

[0011] The fresh-cut fruits and vegetables are washed, peeled and cut, and then placed in water for standby; then put into the preservative for soaking, and after being taken out and dried, packaged and stored at low temperature.

[0012] Pyroglutamic acid is used as the only or main active component in the fresh-cut fruits and vegetables anti-browning agent. For example, pyroglutamic acid can be dissolved in water or other solvents to prepare the fresh-cut fruits and vegetables anti-browning agent, preferably the concentration of pyroglutamic acid in the anti-browning agent is 0.1g / L-3.5g / L.

[0013] As a preferred embodiment in the present application, the following steps are included:

[0014] The fresh-cut fruits and vegetables are washed, peeled and cut, and then placed in water for standby; then put into the preservative for soaking, and after being taken out and dried, packaged and stored at low temperature.

[0015] Further, the fresh-cut fruits and vegetables described above include but are not limited to potatoes, lettuce or lotus root slices.

[0016] Further, in the above application method, the mass ratio of fresh-cut fruits and vegetables to preservative, anti-browning agent or bacteriostatic agent is preferably as large as possible, and the minimum is 1:2.

[0017] As a preferred embodiment in the present application, the above application includes the following specific steps: (1) washing and peeling the fresh fruit and vegetable raw materials: washing the surface soil of the raw materials with clean water, then peeling, and then soaking the peeled raw materials in water for cutting;

[0018] (2) slicing treatment: after the raw materials treated in step (1) are sliced, they are soaked in cold water until all the samples are cut, and then taken out;

[0019] (3) preservation treatment: the raw materials treated in step (2) are soaked in preservative, anti-browning agent or bacteriostatic agent, taken out and dried;

[0020] (4) packaging and storage: packaged with fresh-keeping packaging film and stored at low temperature.

[0021] As preferred, the slicing machine is used in step (2) to slice into 3-4mm slices.

[0022] As preferred, the soaking time in step (3) is 2min.

[0023] As preferred, the low temperature in step (4) is 0-4℃.

[0024] Compared with the prior art, the present application has the following beneficial effects:

[0025] (I) The pyroglutamic acid is prepared into pyroglutamic acid solution, which has good fresh-keeping effect on fresh-cut fruits and vegetables.

[0026] (II) The pyroglutamic acid is prepared into pyroglutamic acid solution, which has good anti-browning effect on fresh-cut fruits and vegetables.

[0027] (III) The pyroglutamic acid is prepared into pyroglutamic acid solution, which has good bacteriostatic effect on fresh-cut fruits and vegetables.

[0028] (IV) The pyroglutamic acid is prepared into pyroglutamic acid solution, which is used for fresh-cut fruits and vegetables, can reduce the browning of fresh-cut fruits and vegetables, has good sterilization effect, and prolongs the shelf life of fresh-cut fruits and vegetables.

[0029] (V) The present application is used for fresh-cut fruits and vegetables processing, which has the characteristics of safety, high efficiency and environmental protection under the premise of ensuring the fresh-keeping effect, anti-browning effect and bacteriostatic effect of fresh-cut products. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 The color difference L* value change of fresh-cut potatoes in Example 4;

[0031] Figure 2 The color difference a* value change of fresh-cut potatoes in Example 4;

[0032] Figure 3 The appearance of fresh-cut potatoes in Example 4 for 12h;

[0033] Figure 4 The microbial growth of fresh-cut potatoes in Example 4 for 24h;

[0034] Figure 5 The color difference L* value change of fresh-cut lettuce in Test Example 5;

[0035] Figure 6 The color difference a* value change of fresh-cut lettuce in Test Example 5;

[0036] Figure 7 The appearance of fresh-cut lettuce in Test Example 5 for 4d;

[0037] Figure 8 Microbial growth of fresh-cut lettuce on the 4th day in Test Example 5;

[0038] Figure 9 Color difference L* value change of fresh-cut lotus root slice in Test Example 6;

[0039] Figure 10 Color difference a* value change of fresh-cut lotus root slice in Test Example 6;

[0040] Figure 11 Appearance of fresh-cut lotus root slice on the 24th hour in Test Example 6;

[0041] Figure 12 Appearance of fresh-cut potato on the 4th day in Test Example 7;

[0042] Figure 13 Molecular docking 2D diagram of pyroglutamic acid and PPO interaction;

[0043] Figure 14 PPO activity change diagram of fresh-cut potato. DETAILED DESCRIPTION

[0044] The specific operation process is described in detail through specific examples, but the present application is not limited to the following examples: the method is a conventional method unless otherwise specified, and the raw materials can be obtained from public commercial channels unless otherwise specified:

[0045] Example 1:

[0046] A fresh-cut fruit and vegetable preservative 1#, which contains pyroglutamic acid with a concentration of 0.1 g / L, and the rest is water.

[0047] Preservative 2#, preservative 3#, preservative 4#, preservative 5#, preservative 6#, preservative 7#, and preservative 8# are prepared according to the above steps, and the above preservatives contain pyroglutamic acid with a concentration of 0.5 g / L, 1.0 g / L, 1.5 g / L, 2.0 g / L, 2.5 g / L, 3 g / L, and 3.5 g / L, respectively, and the rest is water.

[0048] Example 2:

[0049] A fresh-cut fruit and vegetable anti-browning agent 1#, which contains pyroglutamic acid with a concentration of 0.1 g / L, and the rest is water.

[0050] Anti-browning agent 2#, anti-browning agent 3#, anti-browning agent 4#, anti-browning agent 5#, anti-browning agent 6#, anti-browning agent 7#, anti-browning agent 8# are prepared according to the above steps, and the above anti-browning agents respectively contain pyroglutamic acid with a concentration of 0.5 g / L, 1.0 g / L, 1.5 g / L, 2.0 g / L, 2.5 g / L, 3 g / L, 3.5 g / L, and the rest is water.

[0051] Example 3:

[0052] A fresh-cut fruit and vegetable anti-browning agent 1# contains pyroglutamic acid with a concentration of 0.1 g / L, and the rest is water.

[0053] Anti-browning agent 2#, anti-browning agent 3#, anti-browning agent 4#, anti-browning agent 5#, anti-browning agent 6#, anti-browning agent 7#, anti-browning agent 8# are prepared according to the above steps, and the above anti-browning agents respectively contain pyroglutamic acid with a concentration of 0.5 g / L, 1.0 g / L, 1.5 g / L, 2.0 g / L, 2.5 g / L, 3 g / L, 3.5 g / L, and the rest is water.

[0054] Example 4:

[0055] The method for preserving fresh-cut products using the fresh-cut fruit and vegetable preservative 1# and 3# prepared in Example 1 includes the following steps:

[0056] The test raw material is fresh potatoes, which are selected after harvesting to be uniform in size and maturity, and free of residual, diseased, and inferior potatoes.

[0057] The surface of the raw material is washed with clean water, and a stainless steel tool is used to peel the raw material. The peeled raw material is soaked in water before being cut;

[0058] The peeled raw material obtained in the above step is cut into 3-4 mm slices using a slicing machine and soaked in cold water. After all the samples are cut, they are taken out;

[0059] The potato slices obtained in the above step are soaked in preservative 1# and 3# respectively (soaked in clean water as a control), and the soaking time is 2 min. After soaking, the excess water is shaken off;

[0060] The treated potato slices are placed in 0.1 mm packaging bags and stored at (4±0.5)℃.

[0061] The appearance and color of the potato slices are detected after 3, 6, 12, and 24 hours of storage, and the microbial growth of the potato is detected after 24 hours. The specific results are shown in Figures 1-4 .

[0062] The results show that the potato slices treated with the fresh-cut fruit and vegetable preservative 1# and 3# have better color and lower microbial growth than the control group. Figures 1-4It can be seen that the control potatoes have already turned brown visibly 3 hours after being cut; while the potato slices treated with preservatives 1# and 3# solutions still have a good appearance until 24 hours.

[0063] In addition, by measuring the microorganisms of the 24h samples, it was found that L-PA can significantly inhibit bacterial growth. 0.1g / L and 1g / L pyroglutamic acid solutions inhibited microbial growth by approximately 18.2% and 22.7%, respectively.

[0064] Example 5:

[0065] A method for preserving fresh-cut fruits and vegetables using the fresh-cut fruit and vegetable preservative 8# prepared in Example 1 comprises the following steps:

[0066] Use clean water to rinse the dirt on the surface of fresh lettuce, peel it with stainless steel tools, soak the peeled lettuce in water and wait for cutting;

[0067] The peeled raw material obtained in the above step was cut into 3-4 mm thin slices using a slicer, and soaked in cold water. After all the samples were cut, they were fished out;

[0068] The lettuce slices treated in the above steps were immersed in preservative 8# (the final concentration of pyroglutamic acid in the pyroglutamic acid solution was 3.5 g / L) (the slices immersed in water were used as a control, and the rest of the steps were the same) for 2 minutes, then removed and the excess water was shaken off;

[0069] The treated lettuce slices were packed into 0.1mm packaging bags and stored at a low temperature of 4±0.5℃. The color change of the lettuce slices was detected after 2 and 4 days of storage, and the microbial growth of the lettuce slices was detected after 4 days of storage. The specific results are shown in Figures 5-8 .

[0070] Depend on Figures 5-8 As can be seen, the fresh-cut lettuce showed no visible quality deterioration after two days on the shelf. On the fourth day, the control lettuce showed noticeable browning, while the treated group's appearance was significantly better than the control. Microbiological testing of the four-day samples revealed that pyroglutamic acid significantly inhibited bacterial growth, with 3.5 g / L pyroglutamic acid inhibiting microbial growth by approximately 23.2%.

[0071] Example 6:

[0072] A method for preserving fresh-cut fruits and vegetables using the fresh-cut fruit and vegetable preservatives 2# and 3# prepared in Example 1 comprises the following steps:

[0073] Use clean water to rinse the dirt on the surface of the fresh lotus root, peel it with stainless steel tools, soak the peeled raw material in water and wait for cutting;

[0074] The peeled raw material obtained in the above step was cut into 3-4 mm slices by a slicing machine, and was soaked in cold water. After all the samples were cut, they were taken out;

[0075] The lotus root slices treated in the above step were respectively soaked in preservatives 2# and 3# (the final concentration of pyroglutamic acid in the pyroglutamic acid solution was 0.5 g / L and 1 g / L) (water soaking was used as a control, and the remaining steps were the same), the soaking time was 2 min, and the samples were taken out and dried;

[0076] The treated lotus root slices were packed in 0.1 mm packaging bags and stored at a temperature of 20±0.5℃. The appearance and color change of the lotus root slices were detected after 6 h and 24 h of storage, respectively, and the specific results are shown in Figures 9-11 .

[0077] It can be known from Figures 9-11 that the fresh-cut lotus root slices did not have visible quality deterioration after 6 h of storage. After 24 h of fresh cutting, the control lotus root slices showed obvious browning, and the appearance of the lotus root slices treated with 1 g / L was significantly better than that of the control group.

[0078] Example 7:

[0079] The fresh-cut potatoes were treated with common preservatives on the market (0.3% ascorbic acid, 300 mg / L peroxyacetic acid, 150 mg / L salicylic acid, 35 mg / L peroxyacetic acid, 100 mg / L sodium hypochlorite, 10% ethanol, 20% ethanol, and 30% ethanol) for 2 min, and water soaking was used as a control.

[0080] The treated potato slices were packed in packaging bags and stored at a low temperature of 4±0.5℃. The appearance of the lettuce slices was detected after 4 d of storage, and the specific results are shown in Figure 12 .

[0081] It can be known from Figure 12 that the appearance of the potato slices treated in each group deteriorated obviously compared with the samples on the day of cutting and division (day 0). Among them, the antioxidants ascorbic acid and salicylic acid did not significantly delay the browning of fresh-cut potatoes compared with the control, and did not have antibacterial ability; the antibacterial agents peroxyacetic acid, hydrogen peroxide, sodium hypochlorite, and ethanol all accelerated the browning of fresh-cut potatoes compared with the control. Compared with the preservation method provided by the present application, the effect is not good, and the action is single.

[0082] Mechanism of action of pyroglutamic acid:

[0083] Pyroglutamic acid is an acidic non-protein amino acid derivative, containing a hydroxyl group, and its solution is acidic. As the concentration increases, the pH value decreases, and the effect of inhibiting potato browning is better. The pH value of 1 g / L pyroglutamic acid solution is 2.47. The interaction between pyroglutamic acid and the three-dimensional crystal structure of polyphenol oxidase (PPO) was simulated by molecular docking. It was found that the binding energy of pyroglutamic acid and PPO was-5.3 kcal / mol. Pyroglutamic acid binds near the binuclear copper active center of PPO, and interacts with the surrounding amino acid residues His 259, Asn 260, Val 283, Phe 264, Gly 281, Ser 282, Ala 286, His 263 and His 61 through van der Waals force. The hydroxyl group on the branched chain of pyroglutamic acid can also form a hydrogen bond with Met 280, and the carbonyl group on the nitrogen heterocycle forms a hydrogen bond with His 85. The 2D graph of the molecular docking of pyroglutamic acid and PPO interaction Figure 13 ) shows that L-PA interacts with the amino acids around the active center of the enzyme, which may induce a change in the conformation of the enzyme, hinder the phenolic substrate from entering the active pocket of the enzyme, and thus reduce the catalytic activity of PPO, thereby producing an anti-browning effect. Therefore, we detected the activity of PPO in the potato chips treated with pyroglutamic acid in Example 4, and the specific results are shown in Figure 14 , the PPO activity change graph of fresh-cut potato in Example 4 is shown in Figure 14 It was found that pyroglutamic acid can significantly inhibit the PPO activity of fresh-cut potato during the shelf life, and as the concentration increases, this inhibitory effect lasts longer and the anti-browning effect is better.

[0084] It can be seen that exogenous pyroglutamic acid can delay the browning of fresh-cut fruits and vegetables by inhibiting the activity of PPO, which may inhibit the activity of PPO by reducing the pH value and forming interaction force with the amino acid residues of PPO, thereby inhibiting the generation of browning.

[0085] The above shows and describes the basic principles and main features of the present application and the advantages of the present application. The above examples and descriptions described in the specification are only to illustrate the principles of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements will fall within the scope of the claimed present application. The scope of protection claimed by the present application is defined by the appended claims and their equivalents.

Claims

1. Pyroglutamic acid as the only or main active component in the application of fresh-cut fruit and vegetable anti-browning agent, wherein the concentration of pyroglutamic acid is 0.1 g / L-3.5 g / L.

2. Use according to claim 1, characterized in that: The fresh-cut fruit and vegetable includes potato, lettuce or lotus root slice.

3. Use according to claim 2, wherein The method comprises the following steps: The fresh-cut fruit and vegetable is cleaned, peeled and cut, and then placed in water for standby; then soaked in the anti-browning agent, taken out, and dried to pack, and then stored at low temperature.

4. Use according to any one of claims 1 to 3, wherein: The mass ratio of fresh-cut fruit and vegetable to anti-browning agent is >1:2.

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