L-tert-leucine application method for improving quality and storability of gala apple

Abstract

The application relates to an application method of L-tert-leucine for improving the quality and storability of Gala apples, which comprises the following steps: selecting a test apple orchard base, selecting Gala apple trees, and spraying different concentrations of exogenous L-tert-leucine on the selected test apple trees in a fruit development period; picking 8-9 mature Gala fruits, storing the fruits, and comparing the fruit quality indexes of different groups and comparing various measured data. According to the application method, spraying 500 mg / L mass concentration L-tert-leucine on the leaves of Gala apples in a growth period can significantly promote the yellow coloration and brightness increase of the Gala apples at the time of harvesting, improve the fruit hardness, TSS content, TA content, soluble protein content and free amino acid content, is beneficial to maintaining the fruit hardness and soluble protein content during cold storage, delaying the decrease of the fruit hardness and soluble protein content, inhibiting the decrease of the TSS content and TA content and the increase of the free amino acid during cold storage, and keeping the Gala apple fruits with lower POD activity and higher SOD activity.

Description

Technical Field

[0001] This invention belongs to the field of product preservation technology, specifically the application of L-tert-leucine in improving the quality and storage preservation of Gala apples. Background Technology

[0002] Gala apples are the most important early-maturing variety, with a golden-yellow skin, a light red blush on the sun-exposed side, and discontinuous wide red stripes. They are popular with consumers due to their early market availability, golden-yellow flesh, and sweet-tart flavor. However, they suffer from poor storage quality, with the flesh easily becoming mealy and soft. Biostimulants can increase yield, improve fruit quality, enhance the absorption and utilization of plant nutrients, and improve the tree's resistance to adverse conditions. Among these, amino acid biostimulants are particularly effective in improving the resistance and quality of apple fruit.

[0003] L-tert-leucine is a non-proteinogenic chiral amino acid widely used in medicine, food, pesticides, and animal husbandry. It can be used to produce feed and nutritional additives, synthesize anticancer drugs, bioinhibitors, and other peptide drugs. It is also frequently used as a substitute for valine and leucine in peptide synthesis, and has broad application prospects in agricultural production. Currently, there are no reports on the application of L-tert-leucine in plants.

[0004] (a) Technical problems to be solved

[0005] In view of the poor storage properties of Gala apples, this invention provides a method for applying L-tert-leucine to improve the quality and storage properties of Gala apples.

[0006] (II) Technical Solution

[0007] To achieve the above objectives, the present invention provides the following technical solution: a method for applying L-tert-leucine to improve the quality and storability of Gala apples, comprising the following steps:

[0008] S1: Select the experimental apple orchard site and choose the experimental apple trees;

[0009] S2: During the fruit development period, different concentrations of exogenous L-tert-leucine were sprayed on the leaves of the selected experimental apple trees in the above steps, while a control was set up by spraying with water.

[0010] S3: Harvest apples that are 80-90% ripe, store them, and compare the fruit quality indicators between different groups. Measure and compare the various test data.

[0011] Preferably, the apple trees tested in S1 are Gala apple trees, 7 years old, and bagged during the fruit growth period.

[0012] In a further preferred embodiment, the purity of L-tert-leucine in S2 is ≥99%.

[0013] In a further preferred embodiment, the mass concentration of L-tert-leucine in S2 is 0 (control, CK), 50, 100, 500, 1000, and 5000 mg / L, where CK is the sprayed water.

[0014] In a further preferred embodiment, L-tert-leucine is sprayed onto the leaves of developing fruit three times in S2.

[0015] In a further preferred embodiment, after harvesting the fruit in S3, the fruit is immediately placed in a cold storage for pre-cooling and preparation. Fruits with uniform maturity and free from disease, insects, damage, or browning are selected, packaged in high-permeability bags, sealed, placed in packaging cartons, and stored in a cold storage at (0±1)℃ and relative humidity of 85% to 95%.

[0016] In a further preferred embodiment, the measurement data in S3 include the determination of fruit color difference, fruit firmness, soluble solids (TSS) content, titratable acid (TA) content, peroxidase (POD) activity, superoxide dismutase (SOD) activity, soluble protein and free amino acid content.

[0017] (III) Beneficial Effects

[0018] Compared with the prior art, the present invention provides a method for applying L-tert-leucine to improve the quality and storability of Gala apples, which has the following beneficial effects:

[0019] The application method described in this invention involves foliar spraying of Gala apples with L-tert-leucine during the fruit's growth period. This treatment increases the content of TSS, TA, amino acids, and soluble protein at harvest, helps maintain fruit firmness and delays its decline, and keeps TSS, TA, and protein content at high levels during storage. It also inhibits the increase of free amino acids, resulting in lower POD and higher SOD activity in the fruit. The 500 mg / L treatment showed the best effect; Gala apples treated at this concentration exhibited significantly better firmness, TSS, TA, and soluble protein content than the control. After 75 days of storage, the Gala apples retained their sweet and sour taste and crisp texture well. Therefore, foliar spraying with 500 mg / L exogenous L-tert-leucine three times during the Gala apple fruit development period is beneficial for improving the harvest quality and storability of the fruit. Attached Figure Description

[0020] Figure 1 This is a comparison diagram of the effect of L-tert-leucine on the peel color of Gala apples in this invention;

[0021] Figure 2 This is a comparative diagram showing the effect of L-tert-leucine on the hardness of Gala apples during storage in this invention;

[0022] Figure 3This is a comparative diagram showing the effect of L-tert-leucine on the TSS content of Gala apples during storage in this invention.

[0023] Figure 4 This is a comparative diagram showing the effect of L-tert-leucine on the TA content of Gala apples during storage in this invention;

[0024] Figure 5 This is a comparative graph showing the effect of L-tert-leucine on the soluble protein content of Gala apples during storage.

[0025] Figure 6 This is a comparative diagram showing the effect of L-tert-leucine on the content of free amino acids in Gala apples during storage.

[0026] Figure 7 This is a comparative diagram showing the effect of L-tert-leucine on POD activity of Gala apples during storage in this invention;

[0027] Figure 8 This is a comparative diagram showing the effect of L-tert-leucine on SOD activity during Gala apple storage in this invention. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] Example:

[0030] Please refer to Table 1, Table 2 and Figure 1-8 A method for applying L-tert-leucine to improve the quality and storability of Gala apples includes the following steps:

[0031] S1: Select the experimental apple orchard site, select experimental apple trees, and group them accordingly;

[0032] S2: During the fruit development period, different concentrations of exogenous L-tert-leucine were sprayed on the leaves of the selected experimental apple trees in the above steps, while a control was set up by spraying with water.

[0033] S3: Harvest apples that are 80-90% ripe, selecting those with uniform maturity and free from disease, insects, damage, or browning. Pack them in high-permeability preservation bags, seal them tightly, place them in cardboard boxes, and store them in a cold storage at (0±1)℃ and 85%-95% relative humidity. Quality indicators of the fruits from different groups were measured during 0-75 days of storage, both at harvest and during storage, and the measured data were compared.

[0034] ①The effect of L-tert-leucine on the harvest quality of Gala apples

[0035] Table 1 shows that pre-harvest spraying of L-tert-leucine can improve the weight of Gala apples. The 500 mg / L treatment significantly increased the weight of a single fruit (247.58 g), an increase of 8.3% compared to the control (228.55 g). Pre-harvest spraying of L-tert-leucine can affect fruit quality. Relatively low concentrations (50-500 mg / L) can improve Gala apple fruit firmness, TSS content, TA content, soluble protein, and free amino acid content to varying degrees. High concentrations (1000-5000 mg / L) actually reduce all quality indicators, with firmness showing the most significant effect. Therefore, the 500 mg / L treatment has the best effect.

[0036] Table 1. Effects of L-tert-leucine on harvest quality of Gala apples

[0037]

[0038] ② Effects of L-tert-leucine on the quality of Gala apples after 75 days of storage

[0039] As shown in Table 2, after 75 days of storage, the hardness of the control group was 6.52 kg / cm². 2 The hardness of the 50-500 mg / L treatment was significantly higher than that of the control, while the hardness of the 1000 mg / L and 5000 mg / L treatments was lower than that of the control. The hardness of the 5000 mg / L treatment was 6.20 kg / cm². 2The lowest TSS content was observed in all treatments except the 1000 mg / L treatment, which showed the lowest TSS content (15.20%) compared to 60 days of storage. The control, 50 mg / L, and 100 mg / L treatments showed the largest increases, with the 100 mg / L treatment (15.73%) showing the highest TSS content and the 5000 mg / L treatment (14.53%) showing the lowest. Gala apples treated with 500 mg / L and 1000 mg / L had a crisp texture and the flesh remained intact. L-tert-leucine treatments at 50-500 mg / L were beneficial for maintaining the TA content of Gala apples during storage. The 500 mg / L treatment had the highest soluble protein content (116.7 mg / kg), compared to the control. Other treatments, except for the 000 mg / L treatment, showed significant differences. The control had the lowest soluble protein content (95.9 mg / kg), and the 500 mg / L L-tert-leucine treatment effectively inhibited the decrease in soluble protein content in Gala apples. L-tert-leucine treatment reduced the increase in free amino acid content in Gala apples to varying degrees. Treatments ranging from 50 to 1000 mg / L maintained the free amino acid content in Gala apples at a low level at the end of storage, with the 1000 mg / L treatment showing the best effect. The control had the highest POD activity [19.56 U / (min·g)], while the 500 mg / L treatment had the lowest POD activity [8.09 U / (min·g)] and the 500 mg / L treatment had the highest SOD activity [29.64 U / (min·g)], with significant differences from the control. Pre-harvest spraying of L-tert-leucine with 500 mg / L can maintain Gala apples with lower POD and higher SOD activity.

[0040] Table 2. Effects of L-tert-leucine on the quality of Gala apples after 75 days of storage.

[0041]

[0042] ③The effect of L-tert-leucine on the peel color of Gala apples, such as Figure 1 As shown:

[0043] Low-concentration treatments (50-500 mg / L) resulted in higher L*, h*, and b* values ​​for Gala apples compared to the control, while lower a* values. Specifically, 500 mg / L significantly increased L* and h* values, and 100 mg / L significantly increased b* and h* values. These lower concentrations of L-tert-leucine improved the brightness and yellowness of Gala apples. While high-concentration (1000 mg / L and 5000 mg / L) L-tert-leucine treatments reduced fruit brightness and yellowness, the differences between these concentrations and the control were not statistically significant. These results indicate that 100 mg / L and 500 mg / L L-tert-leucine treatments effectively improve the yellowness and brightness of Gala apples.

[0044] ④ The effect of L-tert-leucine on the firmness of Gala apples during storage, such as Figure 2 As shown:

[0045] Depend on Figure 2 It was found that the firmness of Gala apples generally decreased during storage, with the firmness decreasing continuously with prolonged storage time. Treatments with 50 mg / L and 100 mg / L maintained relatively high firmness levels during storage, showing significant differences from the control. Treatments with 1000 mg / L and 5000 mg / L had lower firmness, with the 5000 mg / L treatment showing significantly lower firmness than the control at all storage stages. Before 30 days of storage, the fruit firmness decreased rapidly, after which the rate of decrease slowed. At 75 days of storage, the control firmness was 6.52 kg / cm². 2 The 50-500 mg / L treatment resulted in significantly higher fruit firmness than the control, while the 1000 mg / L and 5000 mg / L treatments resulted in lower firmness than the control. These results indicate that relatively low concentrations of L-tert-leucine (50-500 mg / L) can delay the decline in fruit firmness during storage and improve fruit storability. Among these, the 100 mg / L L-tert-leucine treatment showed the best effect in maintaining firmness.

[0046] ⑤ The effect of L-tert-leucine on the TSS content of Gala apples during storage, such as Figure 3 As shown:

[0047] Depend on Figure 3 It can be seen that the TSS content in Gala apples initially increased and then decreased. Throughout the storage period, the TSS content in the 50 mg / L and 100 mg / L treatments was significantly higher than the control, while the TSS content in the 5000 mg / L treatment was significantly lower than the control. Before 60 days of storage, the TSS content in the 500-1000 mg / L treatment was significantly higher than the control. At 75 days of storage, due to factors such as fruit dehydration and flesh softening, the TSS content in all treatments except the 1000 mg / L treatment increased, but the TSS content in the 500 mg / L treatment (15.2%) showed the smallest increase compared to 60 days of storage. Therefore, the 500 mg / L and 100 mg / L treatments are beneficial for maintaining the TSS content of Gala apples during storage, resulting in better storage performance, as evidenced by the crisp texture and unsoftened flesh of Gala apples treated with the 500 mg / L and 1000 mg / L treatments.

[0048] ⑥The effect of L-tert-leucine on the TA content of Gala apples during storage, such as Figure 4 As shown:

[0049] Depend on Figure 4It can be seen that the titratable acid (TA) content in the pulp of the different treatments showed different trends throughout the storage period. Except for the control, the TA content in the pulp of the other treatments showed a trend of first increasing and then decreasing with the increase of storage time. After 15 days of storage, except for the 500 mg / L and 5000 mg / L treatments, the TA content of the other treatments increased slightly compared with the harvest time. The TA content of the 50–1000 mg / L treatment was higher than that of the control group, and the difference was significant. After 60 days of storage, except for the 5000 mg / L treatment, the TA content of the other treatments increased compared with 45 days. The TA content of the 50–500 mg / L treatment was significantly higher than that of the control. After 75 days of storage, the TA content of the 50 mg / L treatment (4.69 g / L) was the highest, followed by the TA content of the 500 mg / L treatment (4.65 g / L). The TA content of the 50–500 mg / L treatment was significantly higher than that of the control, while the 1000 and 5000 mg / L treatments were significantly lower than that of the control. It can be seen that preharvest L-tert-leucine treatment can increase the TA content of Gala apples to varying degrees, and treatment at 50–500 mg / L is beneficial for maintaining the TA content of Gala apples during storage.

[0050] ⑦ The effect of L-tert-leucine on the soluble protein content of Gala apples during storage, such as Figure 5 As shown:

[0051] Depend on Figure 5 It can be seen that the soluble protein content of Gala apples showed a decreasing trend throughout the entire storage period. After 15 days of storage, there were no significant differences between any treatment and the control. After 30 days of storage, the soluble protein content of the 50 mg / L treatment (146.7 mg / kg) was the highest, followed by the 500 mg / L treatment (145.3 mg / kg), and both treatments were significantly different from the control (132.8 mg / kg). After 45 days of storage, the soluble protein content of the control decreased rapidly, and there were significant differences from all treatments. After 60 days of storage, the soluble protein content of apples in the 50 mg / L treatment decreased rapidly to 109.9 mg / kg, with no significant difference from the control, while the soluble protein content of the 500 mg / L treatment (131.3 mg / kg) was the highest. After 75 days of storage, the soluble protein content of the 500 mg / L treatment (116.7 mg / kg) was the highest, and there were significant differences from all treatments except the 1000 mg / L treatment, while the soluble protein content of the control (95.9 mg / kg) was the lowest. In conclusion, pre-harvest treatment with 500 mg / L L-tert-leucine can effectively inhibit the decrease in soluble protein content during Gala apple storage.

[0052] ⑧ The effect of L-tert-leucine on the content of free amino acids during Gala apple storage, such as Figure 6 As shown:

[0053] Depend on Figure 6It can be seen that, except for the 1000 mg / L treatment, the free amino acid content of other treatments generally showed an increasing trend throughout the storage period. At 15 days of storage, the free amino acid content of the 1000 mg / L treatment decreased, while the free amino acid content of other treatments increased. At 30 days of storage, the free amino acid content of the control and the 100 mg / L treatment was higher than that of the control and other treatments, and the differences were significant. From 45 to 60 days of storage, the free amino acid content of each treatment varied, with the control and the 5000 mg / L treatment having relatively high levels. At 75 days of storage, the free amino acid content of the 5000 mg / L treatment (2631.8 mg / kg) was the highest, and the difference from other treatments was significant. The free amino acid content of the control (2516.7 mg / kg) was second highest, and the free amino acid content of the 50–1000 mg / L treatments was significantly lower than that of the control. The results showed that L-tert-leucine treatment could inhibit the increase of free amino acid content in Gala apples to varying degrees. Treatments of 50–1000 mg / L could keep the free amino acid content in Gala apples at a low level at the end of storage, with 1000 mg / L treatment showing the best effect.

[0054] ⑨ The effect of L-tert-leucine on POD activity during Gala apple storage, such as Figure 7 As shown:

[0055] Depend on Figure 7 It was found that the POD activity of the 5000 mg / L treatment decreased steadily during storage, while the POD activity of other treatments generally showed a trend of first increasing and then decreasing. The peak POD activity of the 500 mg / L treatment occurred at 30 days of storage, while the peak POD activity of the other treatments occurred at 45 days of storage, after which the POD activity decreased. After 30 days of storage, the POD activity of the control apple remained at the highest level and was significantly higher than that of other treatments. At the end of 75 days of storage, the control had the highest POD activity [19.56 U / (min·g)], while the 500 mg / L treatment had the lowest POD activity [8.09 U / (min·g)]. These results indicate that pre-harvest spraying with L-tert-leucine can inhibit the increase of POD activity in Gala apples during storage, with the 500 mg / L treatment showing the best effect.

[0056] ⑩ The effect of L-tert-leucine on SOD activity during Gala apple storage, such as Figure 8 As shown:

[0057] Depend on Figure 7It can be seen that the SOD activity generally showed a trend of first decreasing and then increasing during storage. At 15 days of storage, the SOD activity of the 500 mg / L treatment [20.25 U / (min·g)] was the highest, followed by the 100 mg / L treatment [20.09 U / (min·g)], while the control SOD activity [5.07 U / (min·g)] was the lowest, with significant differences between the two treatments. At 30 days of storage, the SOD activity of the control rapidly increased to 34.51 U / (min·g) and showed a peak activity, significantly higher than other treatments. Among the remaining treatments, the 500 mg / L treatment had the highest SOD activity [19.78 U / (min·g)], while the 1000 mg / L treatment had the lowest [12.33 U / (min·g)]. At 45 days of storage, except for the control, the SOD activity of other treatments increased, with peak activity appearing in the 50 mg / L and 100 mg / L treatments, showing significant differences from the control. At 60 days of storage, the SOD activities of the 500, 1000, and 500 mg / L treatments increased significantly. The peak SOD activity was observed at 000 mg / L, with the highest SOD activity [32.47 U / (min·g)] observed at 500 mg / L. After 75 days of storage, the highest SOD activity [29.64 U / (min·g)] was observed at 500 mg / L, showing a significant difference from the control, while the lowest SOD activity [29.64 U / (min·g)] was observed at 5000 mg / L, showing no significant difference from the control. The results indicate that pre-harvest application of L-tert-leucine can increase the SOD activity of Gala apples, and treatments ranging from 50 to 500 mg / L can maintain a high level of SOD activity during storage, with the 500 mg / L treatment showing the best effect.

[0058] Based on the above experimental data measurement and comparison:

[0059] Foliar application of L-tert-leucine during the Gala apple growing season can increase the content of TSS, TA, amino acids, and soluble protein at harvest, which helps maintain fruit firmness and delays its decline. It also helps maintain high levels of TSS, TA, and protein during storage, inhibits the increase of free amino acids, and keeps the fruit with low POD activity and high SOD activity. The 500 mg / L treatment showed the best effect, with significantly better results in fruit firmness, TSS, TA, and soluble protein content compared to the control. It also significantly increased the weight of individual fruits. After 75 days of storage, the treated fruit maintained a sweet and crisp taste and good quality. Therefore, foliar spraying with 500 mg / L exogenous L-tert-leucine three times during the Gala apple fruit development period is beneficial for improving the harvest quality and storability of the fruit.

[0060] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for applying L-tert-leucine to improve the quality and storability of Gala apples, characterized in that, Includes the following steps: S1: Select the experimental apple orchard site and select Gala apple trees; the experimental apple trees are Gala apple trees, 7 years old, and bagging treatment is carried out during the fruit growth period; S2: During the fruit development period, the selected experimental apple trees were foliar sprayed with exogenous L-tert-leucine at a concentration of 500 mg / L; the purity of L-tert-leucine was ≥99%; L-tert-leucine was sprayed on the leaves of the developing fruit 3 times. S3: Harvest Gala fruits that are 8-9 ripe, select fruits with uniform ripeness, free from disease, insects, damage, and browning, pack them in preservation bags, seal them, put them in packaging cartons, and store them in a cold storage at (0±1)℃ and relative humidity of 85%~95%; the preservation bags are high-permeability preservation bags, and the time in the cold storage is 75 days.

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