A pre-harvest spraying preservative for peach fruit and a spraying method thereof

Abstract

The application discloses a kind of peach fruit preharvest spray preservative and its spraying method, characterized by the following raw materials and mass percentage composition: 2-8% of brown algae oligosaccharide, 0.05-0.2% of gamma-aminobutyric acid, 0.5-2% of capric acid triglyceride, 0.1-0.3% of glycerol, 1-3% of Tween-80, 0.2-1% of sodium carboxymethyl cellulose, and the balance is water, the above-mentioned peach fruit preharvest spray preservative is sprayed on peach fruit, and the method comprises the following steps: selecting peach trees with consistent tree age and growth vigor, starting at 90-110 days after peach fruit blossoming, spraying peach fruit every 3 days, and spraying peach fruit surface uniformly in 3 times until the surface of peach fruit is in a dripping state, which has the advantages of increasing the rate of marketable fruit of picked peach fruit, prolonging the storage period of peach fruit, reducing the rot rate of peach fruit stored at room temperature, reducing cold damage during low-temperature storage, and maintaining the quality and taste of the fruit.

Description

Technical Field

[0001] This invention belongs to the field of fruit and vegetable preservation technology, and in particular relates to a pre-harvest preservative for peaches and its spraying method. Background Technology

[0002] Peaches are typical climacteric fruits, highly susceptible to fungal rot after harvest. Their shelf life at room temperature is only 2-3 days. While low-temperature storage can inhibit fungal rot, chilling injury can easily occur at 2-8℃, significantly reducing their commercial value. Peach preservation techniques mainly rely on low-temperature storage, chemical fungicides, or post-harvest coating treatments, but these methods suffer from high costs, chemical residue risks, and complex operations. Therefore, developing a low-cost, safe, reliable, and simple peach preservation technology is of great significance.

[0003] Fucoidan (AOS), a natural bioactive substance, can significantly enhance the stress resistance of fruits and vegetables and delay post-harvest ripening and senescence through mechanisms such as activating the plant's endogenous antioxidant system, inducing the expression of disease-resistant genes, and delaying cell membrane lipid peroxidation. Gamma-aminobutyric acid (GABA), a naturally occurring non-protein amino acid in plants, exhibits multi-level regulatory effects in enhancing fruit resistance, mainly by activating the antioxidant defense system, strengthening cell structural integrity, and inducing the expression of defense genes to enhance the fruit's resistance to biotic and abiotic stresses. Currently, there are no research reports on the improvement of peach fruit storage tolerance by using a composite nanoemulsion of AOS and GABA. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a pre-harvest preservative for peaches that increases the harvest rate of marketable peaches, extends the storage period of peaches, reduces the rate of decay of peaches during room temperature storage, mitigates low temperature damage, and maintains the quality and taste of the fruit, as well as the spraying method thereof.

[0005] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows: a pre-harvest spray preservative for peach fruits, which is composed of the following raw materials and their mass percentages: 2-8% of fucoidan oligosaccharide, 0.05-0.2% of γ-aminobutyric acid, 0.5-2% of decanoic acid triglyceride, 0.1-0.3% of glycerol, 1-3% of Tween-80, 0.2-1% of sodium carboxymethyl cellulose, and the balance being water.

[0006] Preferably, it is composed of the following raw materials and their mass percentages: 5% fucoidan, 0.1% γ-aminobutyric acid, 1% decanoic acid triglyceride, 0.2% glycerol, 2% Tween-80, 0.5% sodium carboxymethyl cellulose, and the balance being water.

[0007] The present invention also provides a method for spraying the above-mentioned pre-harvest preservative on peach fruits, including the following steps: selecting peach trees of the same age and growth, starting from the 90th to 110th day after the peach fruit blooms, spraying the peach fruit every 2-3 days for a total of 2-4 times, and spraying the surface of the peach fruit evenly until the surface of the peach fruit is dripping with water.

[0008] Preferably, the spraying time is in the early morning or evening.

[0009] Compared with existing technologies, the advantages of this invention are as follows: This invention discloses for the first time a pre-harvest spraying preservative for peaches and its spraying method. AOS and GABA interact synergistically, significantly increasing the harvest rate of marketable peaches, reducing post-harvest rot and chilling injury, and significantly improving the post-harvest disease resistance of peaches, reducing the incidence of disease during storage, and delaying the decline in fruit firmness during storage. Furthermore, it uses decanoic acid triglyceride as the core oil phase component for synergistic emulsification; glycerol is used to reduce the surface tension of the aqueous phase, improving the wettability and spreadability of the emulsion on the fruit's waxy layer, reducing droplet rolling; Tween-80 is used to form a nano-emulsion; and sodium carboxymethyl cellulose is used to enhance the stability of the emulsion and the uniformity of droplets, improving adhesion to the fruit surface.

[0010] In summary, the present invention provides a pre-harvest preservative for peaches and its spraying method. By using the above-mentioned compound preservative for pre-harvest spraying, the commercial fruit rate of harvested peaches is increased, the quality and taste of peaches are improved, post-harvest storage and transportation of peaches are facilitated, the rate of decay of peaches during room temperature storage is reduced, and low-temperature chilling injury is mitigated, thereby improving the overall storage resistance of peaches. Attached Figure Description

[0011] Figure 1 A statistical analysis chart showing the impact of different treatments on the harvestable marketable fruit rate of peaches;

[0012] Figure 2 The analysis of the rotting of peaches after 5 days of storage at 20℃ under different treatments is presented in the figure above, and the statistical analysis figure below.

[0013] Figure 3 A statistical analysis of the incidence rates of postharvest peach fruit puncture wounds after different treatments and storage at 20℃ for 3, 4, and 5 days;

[0014] Figure 4 Statistical analysis of chilling injury index of postharvest peaches stored at 5℃ for 21 and 28 days under different treatments;

[0015] Figure 5 Statistical analysis of the effects of different treatments on the firmness of postharvest peaches stored at 5℃ for 21 and 28 days. Detailed Implementation

[0016] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0017] Example 1: A pre-harvest preservative for peaches, composed of the following raw materials and their mass percentages: 5% fucoidan, 0.1% γ-aminobutyric acid, 1% decanoic acid triglyceride, 0.2% glycerol, 2% Tween-80, 0.5% sodium carboxymethyl cellulose, with the remainder being water.

[0018] Example 2: A pre-harvest preservative for peaches, composed of the following raw materials and their mass percentages: 2% fucoidan, 0.05% γ-aminobutyric acid, 0.5% decanoic acid triglyceride, 0.1% glycerol, 1% Tween-80, 0.2% sodium carboxymethyl cellulose, with the balance being water.

[0019] Example 3, Example 1: A pre-harvest preservative for peach fruits, composed of the following raw materials and their mass percentages: 8% fucoidan, 0.2% γ-aminobutyric acid, 2% decanoic acid triglyceride, 0.3% glycerol, 3% Tween-80, 1% sodium carboxymethyl cellulose, with the balance being water.

[0020] II. Application Examples

[0021] The method of spraying peach fruits with a preservative before harvest, as described in Example 1, involves the following steps: Select peach trees of uniform age and growth. Starting 101 days after the peak flowering period, spray the peach fruits three times, every three days (2-3L per tree). Spray the surface of the peach fruits evenly, ensuring the surface is dripping wet. Spraying time is 5-7 am or 5-7 pm, and this is referred to as the AOS+GABA nanoemulsion group.

[0022] Untreated peaches were set up as a blank control group, denoted as CK group.

[0023] The peaches were sprayed with a preservative before harvest, after which γ-aminobutyric acid (GABA) was removed. This group was designated as the AOS group.

[0024] The peaches were sprayed with a preservative before harvest to remove the oligosaccharides from the brown algae, and this group was designated as the GABA group.

[0025] III. Results Analysis

[0026] 1. Effects of different treatments on the harvestable marketable fruit rate of peaches

[0027] Experimental Methods: Observe the total number of initial fruits on each tree 100 days after flowering (counted before spraying) and the number of finally mature and undiscarded fruits in each treatment group (only count intact, healthy, and unfallen fruits). Calculate the marketable fruit rate per tree using the following formula: Marketable fruit rate (%) = Number of marketable fruits / Number of fruits 100 days after flowering × 100%.

[0028] Peach fruits are susceptible to environmental stress and pathogenic microorganism infection during flowering and after fruit set, leading to a significant decrease in the marketable fruit rate. For example... Figure 1 As shown, pre-harvest spraying with AOS, GABA, and AOS+GABA nanoemulsions all improved the overall marketable fruit rate. The marketable fruit rates of the pre-harvest sprayed AOS and GABA groups were 53% and 51.6%, respectively, significantly higher than the control group (41.6%) by 27.4% and 24.0%. The marketable fruit rate of the pre-harvest sprayed AOS+GABA nanoemulsion group was significantly higher than the other groups, reaching 85.0%, a substantial increase of 104.3% compared to the control group. This indicates that the combination of AOS and GABA has a synergistic effect, significantly improving the harvestable marketable fruit rate of peaches.

[0029] 2. Effects of different treatments on postharvest peach fruit rot

[0030] In the following experiments, each treatment—CK group, AOS group, GABA group, and AOS+GABA nanoemulsion group—contained 6 peach trees, serving as 6 independent biological replicates. When the fruits reached commercial harvest maturity, 20 peaches were harvested from each tree, and all fruits from the same treatment group were collected to form an experimental unit of 120 fruits.

[0031] Experimental Method: Fruit rot incidence rate refers to the percentage of fruits showing rot symptoms at the end of the storage period compared to the total number of fruits at the beginning of storage. Fruits were stored at 20℃ for 5 days, and the total number of fruits was recorded at the start of the storage experiment. At the end of the set storage period, the number of all fruits showing any rot symptoms was counted.

[0032] The formula is: Rot rate (%) = Number of rotten fruits / Total number of fruits counted × 100%.

[0033] The results are as follows Figure 2As shown, after 5 days of storage at room temperature, the rot rate of peaches in both the AOS-treated group and the GABA-treated group was 20%, significantly lower than the control group (70%) by 71.4%. This indicates that both AOS and GABA treatments effectively inhibit peach rot, but the AOS+GABA nanoemulsion treatment performed exceptionally well, with no rot occurring in the peaches, achieving a 100% reduction compared to the control group, thus achieving complete preservation. This demonstrates that the combination of AOS and GABA has a synergistic effect, significantly improving the storage resistance of peaches.

[0034] 3. Effects of different treatments on postharvest disease resistance of peach fruits

[0035] In the following experiments, each treatment—CK group, AOS group, GABA group, and AOS+GABA nanoemulsion group—contained 6 peach trees, serving as 6 independent biological replicates. When the fruits reached commercial harvest maturity, 20 peaches were harvested from each tree, and all fruits from the same treatment group were collected to form an experimental unit of 120 fruits.

[0036] Experimental Methods: Artificial puncture wounds were used to simulate pathogen infection, and the effects of different treatments on postharvest disease resistance in peach fruits were investigated. Two 4mm × 4mm wounds were prepared on the equatorial region of the peach fruit using sterile nails. Each fruit wound was inoculated with 10 μL of a 1×10⁻⁶ concentration of pathogen. 5 Spores / mL of American and Australian type of *Streptococcus sclerotiorum* ( Monilinia fructicola Spore suspension. After inoculation, the fruits were placed in a constant temperature and humidity incubator at 20℃ and 90% relative humidity (RH). The disease incidence was observed and recorded 3–5 days after inoculation.

[0037] M. fructicola It is the main pathogen causing post-harvest rot in peaches. For example... Figure 3 As shown, the disease incidence rate in the control group (CK) reached 100% after 3 days of storage, indicating rapid disease development. Pre-harvest AOS and GABA spraying treatments showed some disease inhibition effects in the early storage period (3-4 days), with disease incidence rates of 75% and 81.6%, respectively. However, as the storage time increased to 5 days, the control effect significantly weakened, and the disease incidence rate rose to 100%. Notably, pre-harvest spraying with AOS+GABA nanoemulsion showed excellent disease control throughout the entire storage period. The disease incidence rate was only 20% after 3 days of storage, 80% lower than the CK group; by 5 days of storage, the disease incidence rate was still controlled at 45%, significantly lower than other treatment groups. This indicates that the combined application of AOS and GABA during pre-harvest spraying had a synergistic effect, significantly reducing the disease incidence rate of peaches during storage.

[0038] 4. Effects of different treatments on the chilling injury index of postharvest peaches

[0039] In the following experiments, each treatment—CK group, AOS group, GABA group, and AOS+GABA nanoemulsion group—contained six peach trees, serving as six independent biological replicates. When the fruits reached commercial harvest maturity, 50 peaches were harvested from each tree, and all fruits from the same treatment group were aggregated to form an experimental unit of 300 fruits.

[0040] Experimental method: Peach fruits harvested after spraying were stored in a 5℃ cold storage for 28 days. Every 7 days, the peach fruits were cut open to observe the browning of the flesh. According to the degree of browning, chilling injury can be divided into 5 levels: Level 0, no browning, i.e. no chilling injury occurred; Level 1, browning area is less than 5%, i.e. weak chilling injury; Level 2, browning area is between 5-25%, i.e. moderate chilling injury; Level 3, browning area is between 25-50%, i.e. severe chilling injury; Level 4, browning area is greater than 50%, i.e. severe chilling injury.

[0041] Cold damage calculation formula: Cold damage index = ∑ (number of browned fruits × browning level) / (total number of fruits × highest cold damage level).

[0042] With prolonged storage, the browning of peaches significantly intensified, accompanied by a worsening of chilling injury symptoms. Figure 4 As shown, peaches in the CK group, the pre-harvest AOS spraying group, and the GABA group all experienced chilling injury on day 21 of cold storage, while peaches in the pre-harvest AOS+GABA nanoemulsion group did not experience chilling injury. The chilling injury indices of the pre-harvest AOS, GABA, and AOS+GABA nanoemulsion treatment groups were all lower than those of the CK group, with the AOS+GABA nanoemulsion treatment group showing the most significant effect in controlling chilling injury. On day 28 of cold storage, the chilling injury indices of the CK, AOS, and GABA groups reached 0.88, 0.33, and 0.33, respectively, representing reductions of 63% and 63% compared to the control group. The pre-harvest AOS+GABA nanoemulsion treatment group did not experience chilling injury, and its chilling injury index was reduced by 100% compared to the control group, significantly improving the cold storage quality of the peaches and extending their storage period. This indicates that the combination of AOS and GABA has a synergistic effect, significantly improving the cold resistance of peaches.

[0043] 5. Effects of different treatments on the firmness of peaches during postharvest storage

[0044] The peaches used in this experiment were from the same batch as those used in the four chilling injury experiments mentioned above.

[0045] Experimental method: After spraying, the harvested peaches were stored in a 5℃ cold storage for 28 days. Every 7 days, the hardness of the fruit was measured using a Zhiqu GY-4-1 digital display fruit hardness tester. An 8mm diameter probe was selected, and a plane of about 10mm was cut on each side of the middle of the suture line on the abdomen of the peach. The test handle was held so that the probe was perpendicular to the cross-section of the fruit being tested. The test handle was swung so that the indenter was pressed evenly into the fruit. When the indenter reached the scale line (10mm), the reading of the hardness tester at this moment was the hardness of the fruit, and the unit was N.

[0046] The results are as follows Figure 5 As shown, at 21 and 28 days of storage, the firmness of fruits treated with pre-harvest spraying of AOS, GABA, and AOS+GABA nanoemulsion was significantly higher than that of the control group (CK). This indicates that both single treatment (AOS or GABA) and combined treatment (AOS+GABA nanoemulsion) can effectively delay the decrease in firmness of peach fruits during storage, which is of great significance for maintaining the marketability of the fruit and extending its shelf life. At 21 and 28 days of storage, the firmness of the control group was 16.9 N and 14.4 N, respectively. The firmness of the AOS-treated group at 21 and 28 days of storage was 22.9 N and 19.3 N, respectively, representing increases of 35.5% and 34.0% compared to the control group. Similarly, the firmness of the GABA-treated group at 21 and 28 days of storage was 22 N and 19.5 N, respectively, representing increases of 30.2% and 35.4% compared to the control group. The group treated with pre-harvest AOS+GABA nanoemulsion exhibited firmness as high as 31.9 and 28.0 after 21 and 28 days of storage, respectively, representing increases of 88.8% and 94.4% compared to the control group. Its firmness retention effect was significantly better than that of the AOS and GABA groups alone, and greater than the sum of their effects. These results indicate that the combination of AOS and GABA has a synergistic effect, significantly delaying the decrease in peach firmness during storage and maintaining good quality.

[0047] The foregoing description is not intended to limit the invention, nor is the invention limited to the examples given. Any changes, modifications, additions, or substitutions made by those skilled in the art within the scope of the invention should also be considered within the protection scope of the invention.

Claims

1. A preharvest spray of a peach fruit with a preservative agent, characterized in that The following raw materials and their mass percentages: 2-8% of fucoidan, 0.05-0.2% of gamma-aminobutyric acid, 0.5-2% of capric acid triglyceride, 0.1-0.3% of glycerol, 1-3% of Tween-80, 0.2-1% of sodium carboxymethyl cellulose, and the balance of water.

2. The preharvest spray of claim 1, wherein The following raw materials and their mass percentages: 5% of fucoidan, 0.1% of gamma-aminobutyric acid, 1% of capric acid triglyceride, 0.2% of glycerol, 2% of Tween-80, 0.5% of sodium carboxymethyl cellulose, and the balance of water.

3. A method for spraying the peach fruit with the preservative agent before harvesting the peach fruit according to claim 1 or 2, characterized in that The following steps are included: The peach trees with uniform age and growth vigor are selected, and the peach fruits are sprayed every 2-3 days for 2-4 times, starting from the 90th to 110th day after the peach fruits blossom, and the peach fruit surfaces are uniformly sprayed until the peach fruit surfaces are in a dripping state.

4. The method of claim 3, wherein: The spraying time is in the morning or in the evening.

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