Phytogenic polypeptide HuTAPF18, nucleic acid molecule, fruit and vegetable preservative and application thereof

Abstract

The invention belongs to the field of fruit and vegetable fresh-keeping agents, and particularly relates to a plant-derived polypeptide HuTAPF18, a nucleic acid molecule, a fruit and vegetable fresh-keeping agent and application of the plant-derived polypeptide HuTAPF18. The amino acid sequence of the plant-derived polypeptide HuTAPF18 is as shown in SEQ ID NO. 01. The molecular formula of the plant-derived polypeptide HuTAPF18 provided by the invention is C95H158N30O27, the molecular weight is 2.15 kDa, the isoelectric point is 10.324, and the plant-derived polypeptide HuTAPF18 belongs to a novel biological preservative. HuTAPF18 has a very good inhibiting effect on browning of apple homogenate and easy aging, decay and deterioration of pitaya after picking, and can be widely applied to fresh-keeping and storage of fruits and vegetables.

Description

Technical Field

[0001] The invention belongs to the field of fruit and vegetable preservatives, and specifically relates to a plant-derived polypeptide HuTAPF18, a nucleic acid molecule, a fruit and vegetable preservative and applications thereof. Background Art

[0002] After fruits and vegetables are picked, during the storage and processing process, due to the influence of many unfavorable environmental conditions, the metabolic balance of active oxygen in cells is destroyed, and a large number of free radicals are produced and accumulated, causing damage to the fruits and vegetables after picking, thereby accelerating the browning, aging and death of fruits and vegetables.

[0003] With the rapid development of biotechnology, the preservation technologies used in the field of fruit and vegetable preservation at home and abroad are divided into two aspects. On the one hand, low-temperature freezing preservation technology is used in the processing, transportation and sales of fruits and vegetables, and refrigerator technology is vigorously developed to transport fruits and vegetables to prevent the corruption and deterioration of fresh fruits and vegetables. People have also developed controlled atmosphere preservation technology based on low-temperature refrigeration, which mainly creates a low O2 and high CO2 environment through packaging, and then adjusts the storage environment of fruits and vegetables. However, this method is prone to odor, especially when the temperature control is not good. On the other hand, the addition of food preservatives is used to effectively extend the storage time of fruits and vegetables. Traditional fruit and vegetable preservatives usually have problems such as low potency, large dosage, poor anti-metabolism ability, narrow antibacterial spectrum, and short antibacterial time. After being buried, some fruits and vegetables usually have sour, spicy or other odors. Summary of the invention

[0004] The purpose of the present invention is to provide a plant-derived polypeptide HuTAPF18, which can significantly slow down the browning, weight loss and corruption of fruits and vegetables; can effectively regulate the balance of active oxygen scavenging enzymes such as superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD), reduce cell damage, scavenge free radicals, have a good protective effect on cells, and extend the shelf life.

[0005] The second object of the present invention is to provide a nucleic acid molecule encoding the plant-derived polypeptide HuTAPF18 to solve the above problems.

[0006] The third object of the present invention is to provide a fruit and vegetable preservative to solve the above problems.

[0007] The fourth object of the present invention is to provide the application of the above-mentioned fruit and vegetable preservative.

[0008] In order to achieve the above purpose, the technical solution adopted by the present invention is:

[0009] A plant-derived polypeptide HuTAPF18, whose amino acid sequence is shown in SEQ ID NO.01.

[0010] The plant-derived polypeptide HuTAPF18 provided by the present invention has a molecular formula of C 95 H 158 N 30 O 27 , molecular weight 2.15kDa, isoelectric point 10.324, is a new type of biological preservative. HuTAPF18 has a good inhibitory effect on the browning of apple homogenate and the aging, rotting and deterioration of pitaya after picking, and can be widely used in the preservation and storage of fruits and vegetables.

[0011] A nucleic acid molecule encoding the above-mentioned plant-derived polypeptide HuTAPF18.

[0012] The above-mentioned plant-derived polypeptide HuTAPF18 can be conveniently encoded by using the above-mentioned nucleic acid molecule.

[0013] Preferably, the nucleotide sequence of the nucleic acid molecule is shown in SEQ ID NO. 02. The above-mentioned plant-derived polypeptide HuTAPF18 can be obtained quickly, efficiently and safely using the nucleic acid molecule.

[0014] A fruit and vegetable preservative, the active ingredient of which comprises the above-mentioned plant-derived polypeptide HuTAPF18.

[0015] The fruit and vegetable preservative containing the plant-derived peptide HuTAPF18 as an active ingredient is highly safe, has no toxic or harmful byproducts, is low in pollution, has the functions of sterilization and preservation for fruits and vegetables and other agricultural products, and has no residual toxicity, and can be stored for a long time. It is applied to the storage and preservation of fruits and vegetables and other agricultural products, and has a high use value.

[0016] Preferably, the fruit and vegetable preservative also includes vitamin C. Vitamin C and the plant-derived polypeptide HuTAPF18 can be used together in the processing of fruit and vegetable homogenate, which can effectively inhibit the browning of the fruit and vegetable homogenate, increase the titratable acidity and soluble solids content of the fruit and vegetable juice, improve the conductivity, MDA content, POD enzyme activity and other indicators, and improve the processing quality of the fruit and vegetable juice.

[0017] The above-mentioned plant-derived polypeptide HuTAPF18 and fruit and vegetable preservative are used in scavenging superoxide anion free radicals, preserving fruits and vegetables, and inhibiting browning of fruit and vegetable juice.

[0018] The above-mentioned fruit and vegetable preservative has good application effects in preserving fruits and vegetables and inhibiting browning of fruit and vegetable juice. It is a new type of biological preservative with the advantages of safety, naturalness and health. It has good application prospects to use this biological preservative to replace chemical preservatives in food and fruit and vegetable preservation.

[0019] Preferably, the amount of the plant-derived polypeptide HuTAPF18 used is 0.8-4 μg / mL. Further preferably, the amount of the plant-derived polypeptide HuTAPF18 used is 1-2 μg / mL.

[0020] Preferably, when inhibiting browning of fruit and vegetable juice, vitamin C is added, and the amount of vitamin C added is at least 500 mg / mL. The use of plant-derived polypeptide HuTAPF18 in combination with Vc can further play a synergistic role and further reduce the browning level of pome fruit homogenate. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 ESR signals generated for different treatment groups;

[0022] Figure 2 The browning level of apple homogenate changes after adding different concentrations of Vc in the present invention;

[0023] Figure 3 The browning degree of apple homogenate at different times after adding different concentrations of HuTAPF18 in the present invention;

[0024] Figure 4 The browning level of apple homogenate at different times after treatment with different proportions of compound agents; a~d are the browning states of apple homogenate after 0h, 4h, 8h and 12h, respectively. The test tubes in each group are Vc, Vc and 6.25×10 -8 mol / L HuTAPF18, Vc and 1.25×10 -7 mol / L HuTAPF18, Vc and 2.5×10 -7 mol / L HuTAPF18;

[0025] Figure 5 To investigate the changes in the level of browning of juice over time;

[0026] Figure 6 The effect of different reagent treatments on the titratable acidity of apple homogenate;

[0027] Figure 7 The effect of different reagents on the soluble solid content of apple homogenate;

[0028] Figure 8 The effect of different reagents on the permeability of apple homogenate cells;

[0029] Fig. 9 The effect of different reagents on lipid peroxidation of apple homogenate;

[0030] Fig.10 The effects of different reagents on the POD activity of apple homogenate;

[0031] Fig.11Effects of different treatments on pitaya spoilage; Note: a is blank; b is HuTAPF18 treatment; c is chitosan treatment, where a1, b1, c1 are the appearance of pitaya after 1 day of storage, and a2, b2, c2 are the appearance after 10 days of storage;

[0032] Fig.12 The effect of different treatments on the weight loss rate of pitaya; Note: black is the control group, red is the HuTAPF18 treatment group, and green is the chitosan treatment group;

[0033] Fig.13 The results of recombinant plasmid sequencing. DETAILED DESCRIPTION

[0034] The implementation process of the present invention is described in detail below in conjunction with specific embodiments.

[0035] Example 1 Phytogenic polypeptide HuTAPF18 and nucleic acid molecules, fruit and vegetable preservatives

[0036] The plant-derived polypeptide HuTAPF18 of this embodiment has an amino acid sequence as shown in SEQ ID NO. 01. Its molecular formula is C95H158N30O27, molecular weight is 2.15 kDa, isoelectric point is 10.324; it contains 18 amino acids, encodes a Trypsin-like peptide domain (serine hydrolase-like peptide sequence) fragment, and contains a Tryp_SPc superfamily (serine hydrolase superfamily) functional domain.

[0037] The nucleic acid molecule encoding the plant-derived polypeptide HuTAPF18 has a nucleotide sequence as shown in SEQ ID NO.02.

[0038] In the preparation of the plant-derived polypeptide HuTAPF18 in this example, an expression vector containing the target gene was constructed, and the soluble total protein was extracted after inducing protein expression, and a component with a molecular weight between 2000Da and 3000Da was obtained through purification. This is a self-degradable polypeptide fragment of pitaya serine hydrolase trypsin.

[0039] The specific process is as follows:

[0040] Improved Trizol extraction method: add Trizol extraction solution, chloroform, and isopropanol to pitaya epidermal tissue, centrifuge, ethanol precipitate, dry at room temperature, add DEPC·H2O to dissolve, and obtain total RNA.

[0041] cDNA was synthesized according to the instructions of TakaRa's M-MLV reverse transcriptase, and the synthesized cDNA (diluted 10 times) was used as a template, and PCR amplification was performed using specific primers for the coding region of the polypeptide HuTAPF18 gene. The amplification system was: 2×PFU mixbuffer 12.5μL, upstream primer (SEQ ID NO.03:CCTCTAGAATGttgaccaatgctcac, 10μM) 0.5μL, downstream primer (SEQ ID NO.04:AACCCGGGTTAacgtttcttgagtttaacc, 10μM) 0.5μL, template 1μL, ddH2O 10.5μL. PCR amplification program: 94℃3min; 94℃1min; 61℃1min; 72℃2min; 72℃10min, a total of 30 cycles, stored at 4℃.

[0042] The amplified product was detected by electrophoresis using 1.4% (w / v) agarose gel. The target gene fragment was connected to the expression vector pET28a(+) and transformed into E. coli. The reaction system was: 13.9 μL of target gene fragment, 3 μL of vector large fragment, 2 μL of 10×T4ligase buffer, and 1.1 μL of T4 DNA ligase. The recombinant plasmid after connection (the sequencing results of the recombinant plasmid are shown in Fig.13 coli BL21 competent cells, add IPTG with a final concentration of 0.4 mM, and culture at 28°C, 100 rpm for 24 h to induce protein expression. Add lysozyme with a final concentration of 6 mg / mL, incubate at 37°C for 1 h, then freeze in liquid nitrogen (repeated 3 times to break the cells), centrifuge at 4°C, 12000 rpm for 20 min, and keep the supernatant, which is the soluble total protein.

[0043] The soluble total protein was dissolved in purified water to prepare a solution with a concentration of 5 mg / mL, and ultrafiltration was performed using ultrafiltration membranes with a molecular weight cutoff of 3000Da and 2000Da, and components with a molecular weight between 2000Da and 3000Da were collected and freeze-dried to obtain HuTAPF18 plant-derived polypeptide.

[0044] The fruit and vegetable preservative of this embodiment is the above-mentioned plant-derived polypeptide. The enzyme activity of the polypeptide in removing superoxide anion (O2·-) is tested by ultraviolet spectrophotometry, and its enzyme activity is 500U / mg. In other implementation situations, the fruit and vegetable preservative can be prepared in the form of an aqueous solution of the above-mentioned plant-derived polypeptide, for example, it can be prepared in the form of 14μg / mL (1×10 -6mol / L) of the plant-derived polypeptide HuTAPF18 solution. Other ingredients that can delay the browning of juice or other juice additives can also be further added to construct the fruit and vegetable preservative of the present invention. Other ingredients that can delay the browning of juice, such as vitamin C, etc., can be added at a concentration of 500 to 1000 mg / mL.

[0045] Example 2 Application of plant-derived polypeptide HuTAPF18 in scavenging superoxide anions.

[0046] The plant-derived polypeptide HuTAPF18 of this embodiment is used in the application of scavenging superoxide anions in the following manner: DMSO is used to generate O2 in an alkaline environment. ·- , O2 was detected by hydroxylamine oxidation method ·- ①Blank control group: 17.5μL NaOH (1M) and 1482.5μL ddH2O were added to the test tube in sequence, mixed thoroughly and reacted at room temperature for 30 minutes, and the absorbance was measured at 530nm; ②Blank treatment group: 17.5μL NaOH (1M), 1322.5μL ddH2O and 150μL HuTAPF18 (14μg / mL) were added to the test tube in sequence, mixed thoroughly and reacted at room temperature for 30 minutes, and the absorbance was measured at 530nm; ③Negative control group: 500μL DMSO, 17.5μL NaOH (1M) and 982.5μL ddH2O were added to the test tube in sequence, mixed thoroughly and reacted at room temperature for 30 minutes, and the absorbance was measured at 530nm; ④Positive control group: 0.5mL DMSO, 17.5μL NaOH (1M), 832.5μL ddH2O, 150μL HuTAPF18 (14μg / mL), mix thoroughly and react at room temperature for 30min, and measure the absorbance at 530nm; ⑤ Homogenate blank group: add 0.5mL DMSO, 17.5μL NaOH (1M), 982.5μL apple homogenate (weigh 10g fresh apple pulp, add 200mL double distilled water to make apple homogenate) to the test tube in sequence, mix thoroughly and react at room temperature for 30min, and measure the absorbance at 530nm; ⑥ Homogenate treatment group: add 0.5mL DMSO, 17.5μL NaOH (1M), 832.5μL apple homogenate (weigh 10g fresh apple pulp, add 200mL double distilled water to make apple homogenate), 150μL HuTAPF18 (14μg / mL) to the test tube in sequence, mix thoroughly and react at room temperature for 30min, and measure the absorbance at 530nm. Three independent biological replicates were performed for each group.

[0047] In the above hydroxylamine oxidation system, free radical scavenger Tiron reagent was added to make the final concentration of the scavenger 10mM, mixed, and immediately sucked into a glass capillary with one end closed. After 5 minutes, it was placed in the sample chamber of the German Bruker ER-200D ESR spectrometer to detect superoxide anion signals. The ESR detection results of different treatments are shown in Figure 2. Figure 1 shown.

[0048] Figure 1 In the figure, a is the blank control group, which is the ESR signal generated by the control using Tiron reagent alone; b is the blank treatment group, which is the ESR signal generated by the Tiron reagent control after HuTAPF18 treatment; c is the negative control group, which is the ESR signal generated by the hydroxylamine oxidation method; d is the positive control group, which is the ESR signal generated by the hydroxylamine oxidation method after HuTAPF18 treatment; e is the homogenate blank group, which is the ESR signal generated by the apple homogenate after being placed for 12 hours; f is the homogenate treatment group, which is the ESR signal generated by the apple homogenate after being treated with HuTAPF18 and placed for 12 hours.

[0049] The results of three independent ESR tests showed that the hydroxylamine oxidation system (the initial O2 ·- level was 131.41±6.55nmol / g Fw) or apple homogenate produced O2 ·- ( Figure 1 c and 1e). Tiron reagent alone produces a weak ESR signal in the hydroxylamine oxidation system ( Figure 1 a). Apple homogenate without Tiron reagent and hydroxylamine oxidation system were treated with HuTAPF18 (final concentration of 1.4 μg / mL (1×10 -7 mol / L)) after treatment, the ESR signals were reduced ( Figure 1 f and Figure 1 d).

[0050] Example 3 Fruit and vegetable preservative containing plant-derived polypeptide HuTAPF18 delays browning of apple homogenate

[0051] This example describes the application of a fruit and vegetable preservative containing the plant-derived polypeptide HuTAPF18 in delaying the browning of apple homogenate.

[0052] Weigh 10 g of fresh apple pulp and add 200 mL of double distilled water to make homogenized juice. The titratable acidity of the juice was determined according to GB 12293-90. The soluble solids content of the juice was determined by refractometer. The relative conductivity of the pulp cells was detected according to GB / T 18932.15-2003. The lipid peroxide content of the homogenized juice was determined by thiobarbituric acid (TBA) method. The POD activity of the homogenized juice was determined by colorimetry.

[0053] 1. Optimal concentration of Vc

[0054] To determine the optimal concentration of Vc, Vc was added to the homogenate water to a final concentration of 125, 250, 500, 1000 and 2000 mg / L, respectively. After homogenization (taking 10 min), the effect of Vc on the browning degree of the homogenate was detected. The results are shown in Figure 2 As shown. The calculation method of the ordinate browning index BI is as follows: the color (L*, a*, b*) of the homogenate is measured using a Konica Minolta Co., Ltd. (Japan) CR-400 colorimeter, and the measurement is repeated three times. L* represents white, and the smaller the L* value, the darker it is: a* represents red and green, with a value of "+" for red and "-" for green; b* represents yellow and blue, with a value of "+" for yellow and "-" for blue. The browning index (BI) is calculated using the measured L*, a*, and b*, and the formula is as follows:

[0055] BI=(100(x-0.31)) / 0.172

[0056]

[0057] Depend on Figure 2 It can be seen that when the concentration of Vc is low, 125 mg / L, the browning index is not significantly different from the blank. As the concentration of VC increases, the difference is significant compared with the blank (P<0.05), and both can reduce the browning of apple homogenate. When the concentration of Vc is greater than 1000 mg / L, there is no significant difference in effect with the concentration of Vc of 500 mg / L, so the optimal treatment concentration of Vc is 500 mg / L, which is 2.84 mmol / L.

[0058] 2. Optimal compound concentration

[0059] When the concentration of Vc treatment was 500 mg / mL, the final concentration of HuTAPF18 was 6.25×10 -8 , 1.25×10 -7 and 2.5×10 -7 mol / L (the corresponding final concentrations were 0.875μg / mL, 1.75μg / mL, and 3.5μg / mL), and the effect on the browning degree of the juice after 4, 8, and 12h was measured.

[0060] from Figure 3 It can be seen that within the range of 4 h, as the concentration of HuTAPF18 increases, there is basically no effect on the control of browning. Within the range of 8-12 h, the optimal concentration of adding HuTAPF18 is 1.25×10 -7 mol / L, the compounding effect is the best, which can effectively reduce the browning of apple homogenate, so we choose to mix 500mg / mL Vc and 1.25×10 -7mol / L HuTAPF18 was used as a compounding agent for subsequent experiments. Figure 4 It can be seen intuitively that when 500 mg / mL Vc and 1.25×10 -7 When the homogenate is compounded with 10 mol / L HuTAPF18, its browning can be effectively reduced as the homogenate is placed for a longer time.

[0061] 3. Changes in browning level, titratable acidity, soluble solids content, conductivity, MDA content, and POD enzyme activity of juice in different treatment groups.

[0062] A blank control group, a Vc group (control group + 500 mg / mL Vc), and a HuTAPF18-treated group (control group + 1.25×10 -7 mol / L HuTAPF18), Vc and HuTAPF18 compound treatment group (control group + 500 mg / mL Vc + 1.25×10 -7 mol / LHuTAPF18), and the changes in browning level, titratable acidity, soluble solids content, conductivity, MDA content and POD enzyme activity in different treatment groups were investigated.

[0063] 3.1 Browning level

[0064] Taking Vc as the positive control, the effect of HuTAPF18 and Vc compound on the browning degree of apple homogenate is as follows Figure 5 As shown: During the 12h period, the color of the homogenate was measured at 0h, 4h, 8h and 12h, and the measurement was repeated three times. The results showed that the browning of the apple homogenate in the blank group without any treatment was the most serious. The treatment with Vc or HuTAPF18 alone and the compound agent could effectively reduce the browning. The difference between the group with HuTAPF18 and its compound agent was significant (P<0.05), and the compound agent had the best effect.

[0065] 3.2 Titratable acidity

[0066] from Figure 6 It can be seen that during the homogenization process, the titratable acidity of apple homogenate not treated with reagents was the lowest, that is, the loss of titratable acid was the most serious at this time. As the storage time increased, the titratable acidity of each reagent treatment group decreased. Before 36 hours, the difference between the compound agent treatment group and the blank group was significant (P<0.05), and the titratable acidity was higher than that of other groups.

[0067] 3.3 Soluble solids content

[0068] from Figure 7It can be seen that during the homogenization process, the loss of soluble solid content was the smallest after treatment with Vc and compound agents. As the storage time increased, the soluble solid content of each group showed a downward trend. Among them, there was no significant difference between the compound agent treatment group and the Vc treatment group, but there was a significant difference compared with the blank group (P<0.05).

[0069] 3.4 Conductivity

[0070] Before homogenization, Vc, HuTAPF18 and compound agent were added respectively. According to the above test method, the relative conductivity of apple homogenate was measured after 0, 8, 20 and 36 hours of homogenate. Figure 8 It can be seen that the relative conductivity of each group increased to varying degrees with the extension of time, among which the relative conductivity of the blank group was 59.54%, 66.13%, 73.94% and 84.39%, respectively, and the relative conductivity of the compound group was 60.01%, 61.05%, 64.92% and 73.14%, respectively. Adding Vc treatment can reduce the rate of increase of the relative conductivity of the homogenate, and the compound group has a very significant difference compared with other groups (P<0.01), with the lowest relative conductivity and the smallest increase, that is, the degree of cell damage is the smallest.

[0071] 3.5MDA content

[0072] from Fig. 9 It can be seen that with the extension of storage time, the MDA content of the blank group and the reagent treatment group increased, among which the MDA content of the blank group was 2.73, 3.55, 5.46, and 6.68 nmol / g, the HuTAPF18 treatment group was 1.85, 2.53, 3.85, and 4.93 nmol / g, the Vc treatment group was 1.75, 1.82, 2.34, and 3.05 nmol / g, and the compound treatment group was 1.79, 1.74, 2.13, and 2.75 nmol / g. The MDA content of the blank group increased significantly, and the Vc group and the compound treatment group were significantly different from the untreated group (P<0.01). The slow increase in MDA content can effectively reduce cell damage.

[0073] 3.6 POD enzyme activity

[0074] After apple homogenate was placed for 18 hours, the POD enzyme activity increased significantly, and there was a significant weakening trend after 18 hours. Before 36 hours, the enzyme activity of the HuTAPF18 treatment group increased significantly, and then decreased, and there was no significant difference compared with the blank group. The trend of enzyme activity change in the compound agent treatment was the same as that in the HuTAPF18 treatment group, but the overall enzyme activity was significantly different (P<0.01), and the POD enzyme activity in the compound agent group was lower. In the Vc treatment group, the POD enzyme activity increased slowly before 18 hours, increased sharply at 36 hours, and then slowly decreased, but the difference was significant compared with the compound agent group (P<0.01).

[0075] POD works synergistically with polyphenol oxidase (PPO) to oxidize phenolic substrates to produce quinone-like brown substances. POD enzymes have dual effects. In the late stage of adversity or aging, POD present in cells exhibits a damaging effect, promoting aging and peroxidation, and is the main factor causing browning. Fig.10 It can be seen that the Vc group and the compound agent group can effectively remove excess POD, and the effect is significant compared with the untreated group.

[0076] Based on the above experimental results, it can be seen that Vc has the effect of delaying the browning of juice. Using Vc in combination with the plant-derived peptide HuTAPF18 to treat apple homogenate has the effect of protecting tissue cells, promoting the juice to maintain color, and improving the utilization rate of fruits and vegetables.

[0077] The combination of Vc and plant-derived peptide HuTAPF18 can significantly delay the browning of apple juice. It slows down the increase in relative conductivity, reduces cell permeability, maintains the integrity of cell membrane structure, weakens the substantial increase in MDA (toxic end product of lipid peroxidation metabolism) content, reduces cell damage, reduces peroxidase (POD) activity, prevents or reduces polyphenol oxidase (PPO) and POD from contacting phenolic substrates, and reduces adverse reactions such as browning.

[0078] The plant-derived peptide HuTAPF18 can effectively control the browning of apples during the homogenization process after being compounded with Vc, providing technical feasibility for the quality control of fruit and vegetable juices and reducing the production cost of juices.

[0079] Example 4 Phytogenic polypeptide HuTAPF18 prevents pitaya from spoiling

[0080] This example considers the application of plant-derived polypeptide HuTAPF18 in preventing pitaya from spoiling. Specifically, a is set as a blank control group, b is a HuTAPF18 treatment group, and c is a chitosan treatment group, wherein the concentration of HuTAPF18 is 1.25×10 -7 mol / L, the chitosan concentration was 15 mg / mL, and the treatments b and c were both immersed for 2 minutes.

[0081] Chitosan was used as a positive control, and the effect of HuTAPF18 on the storage quality of pitaya was investigated through intuitive photographic records and determination of weight loss rate. Fig.11It can be seen that after one day of storage, the dragon fruits in each group were bright in color and in excellent condition; after 10 days of storage, the scales of the dragon fruits in the blank group were completely dried up and brittle, the fruit body was dull in color, completely corrupted, and had bacterial spots, making it inedible; the scales of the HuTAPF18-treated group were partially dried up, and the scales on the head began to corrupt, the surface of the peel was smooth and bright in color, and did not affect consumption; the scales of the chitosan-treated group were severely dried up, with multiple rotten and deteriorated areas centered on the bottom of the scales, and most of them were inedible.

[0082] from Fig.12 It can be seen that with the extension of storage time of pitaya, the weight loss rate of each group showed an obvious upward trend. There was no significant difference between the HuTAPF18 treatment group and the chitosan treatment group, but there was a very significant difference between the two groups and the blank group (P<0.01). That is, the treatment with chitosan and HuTAPF18 significantly reduced the water loss of pitaya, delayed its dehydration and reduced quality deterioration.

[0083] In summary, the above experimental results show that the use of appropriate concentrations of plant-derived peptide HuTAPF18 to treat pitaya can significantly reduce the water loss of pitaya, effectively control yellowing and browning, delay aging, and have a certain antibacterial effect, preventing pitaya from spoiling and deteriorating, extending the storage life of pitaya and improving its market value.

[0084] In conclusion, the plant-derived peptide HuTAPF18 is an effective reagent that can provide technical feasibility for the storage quality control of fruits and vegetables. It can be used as an adjuvant for food additives to extend the shelf life of food. In addition, by treating fruits and vegetables by soaking, spraying or applying, and placing them at room temperature, the shelf life of fruits and vegetables can be extended.

Claims

1. A plant-derived polypeptide HuTAPF18, characterized in that: Its amino acid sequence is shown in SEQ ID NO.

01.

2. A nucleic acid molecule encoding the plant-derived polypeptide HuTAPF18 as claimed in claim 1.

3. The nucleic acid molecule according to claim 2, characterized in that Its nucleotide sequence is shown in SEQ ID NO.

02.

4. A fruit and vegetable preservative, characterized in that: The active ingredient comprises the plant-derived polypeptide HuTAPF18 as claimed in claim 1.

5. The fruit and vegetable preservative according to claim 4, characterized in that: Also includes vitamin C.

6. Use of the plant-derived polypeptide HuTAPF18 as claimed in claim 1 and the fruit and vegetable preservative as claimed in claim 4 or 5 in scavenging superoxide anion free radicals, preserving fruits and vegetables, and inhibiting browning of fruit and vegetable juice.

7. The use according to claim 6, characterized in that The dosage of the plant-derived polypeptide HuTAPF18 is 0.8-4 μg / mL.

8. The use according to claim 7, characterized in that The dosage of the plant-derived polypeptide HuTAPF18 is 1-2 μg / mL.

9. The use according to claim 7 or 8, characterized in that When inhibiting browning of fruit and vegetable juice, vitamin C is added, and the amount of vitamin C added is at least 500 mg / mL.

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