Application of chlorogenic acid in improvement of grape fruit quality

Abstract

The invention relates to the technical field of grapes, in particular to application of chlorogenic acid to improvement of grape fruit quality, and the dosage of the chlorogenic acid is 50-200M in mass concentration. The use method comprises the following steps: preparing the chlorogenic acid into a chlorogenic acid aqueous solution, and spraying the chlorogenic acid aqueous solution in a grape fruit swelling period or a grape fruit swelling later period once every 7-12 days for 3-6 times. By applying chlorogenic acid, the anthocyanin content of the grape fruits is remarkably increased, and the coloring effect of the grape fruits can be remarkably improved. By applying the chlorogenic acid externally, the fruit weight, the soluble solid content, the soluble total sugar content and the sugar-acid ratio of the grape fruits are increased, the titratable acid content is reduced, and the flavor and the nutrient content of the grape fruits are improved. The invention promotes the application and development of the chlorogenic acid in the maturation and quality of the grape fruits before harvesting, and solves the problems that the fruit ripening agent in the current market contains hormones and is high in price, the grapes are poor in coloring and slow in color turning, and the potential toxicity exists.

Description

Technical Field

[0001] The present invention relates to the technical field of grapes, and in particular to the application of chlorogenic acid in improving the quality of grape fruits. Background Art

[0002] As living standards continue to improve, people have higher and higher requirements for the quality of fruits. They not only need to have good nutritional value, but also be delicious and beautiful. Vitis vinifera L.) is a vine plant of the genus Vitis in the family Vitaceae. Grapes are sweet and sour, rich in nutritional value, and are deeply loved by the general public. Due to its easy cultivation and strong adaptability, it has played an important role in helping farmers get rich in my country, and has produced good social, economic and ecological benefits. Fruit color, as an important appearance quality of grapes, has become an important indicator for consumers to evaluate the quality of grapes. However, there are still some grape-growing areas that have different degrees of poor coloring and slow color change, such as "Summer Black is not black, Red Earth is not red". Studies have found that the synthesis of anthocyanins in plants can be promoted by applying substances such as ethephon, abscisic acid, gibberellin, and methyl jasmonate, thereby affecting their color. Most of the substances currently studied belong to the category of hormones, so we need a new exogenous substance that is both safe and effective to promote the color change of grape fruits and improve their quality.

[0003] Chlorogenic acid (CGA), also known as 3-O-caffeoylquinic acid, is a phenylalanine metabolite produced during aerobic respiration in plants. It is widely present in plants. Many common agricultural products such as coffee beans, potatoes, apples, grapes, pears, and tobacco leaves contain different amounts of chlorogenic acid. Studies on the role of chlorogenic acid in postharvest fruit development and preservation have shown that exogenous chlorogenic acid can improve the quality of postharvest fruit and extend the storage time of fruit. For example, chlorogenic acid treatment of postharvest 'Kyoho' grape fruit can effectively reduce its grain drop rate and decay rate, maintain the soluble solids, titratable acid and reducing sugar content in the fruit; it can reduce the softening of apple fruit and reduce water loss; and significantly reduce the ethylene release, respiration rate, softening degree, decay rate and malondialdehyde content of nectarine fruit during storage. However, research on fruit quality currently focuses on exogenous chlorogenic acid treatment after harvest, while there are few reports on the growth and development process of fruit and the role of endogenous chlorogenic acid. If chlorogenic acid can be studied and applied in the ripening and quality of pre-harvest grapes, it can greatly promote the research on chlorogenic acid and the progress of fruit ripening agents.

[0004] Therefore, the prior art needs to be further improved. Summary of the invention

[0005] The present invention aims to solve the above problems and provides the application of chlorogenic acid in improving the quality of grape fruit. Chlorogenic acid, as an important secondary metabolite, is used to prematurely ripen grape fruit before harvest and improve its fruit quality. It solves the problems of fruit ripening agents currently on the market containing hormones, being expensive and potentially toxic.

[0006] Specifically, the technical solution provided by this application is as follows: The application of chlorogenic acid in improving the quality of grape fruit, the amount of chlorogenic acid used is 50-200 µM by mass concentration; the method of use is to prepare the chlorogenic acid into a chlorogenic acid aqueous solution, and spray the grape fruit once every 7-12 days, and spray 3-6 times.

[0007] The preparation method of the chlorogenic acid aqueous solution is as follows: weigh 0.177 g of chlorogenic acid powder, dilute to 50 mL with distilled water, and prepare a mother solution with a concentration of 10 mM. 1 mL of 10 mM mother solution is measured and dilute to 200 mL with distilled water, which is a 50 µM chlorogenic acid aqueous solution. The mother solution is diluted in the same way to obtain 100 µM and 200 µM chlorogenic acid aqueous solutions.

[0008] Further preferably, the amount of chlorogenic acid is 50 μM in mass concentration. Experimental verification of multiple grape varieties shows that the exogenous application of chlorogenic acid significantly increases the anthocyanin content of grape fruit. The detection results of anthocyanin synthase gene expression levels show that the relative expression levels of anthocyanin synthase genes after exogenous chlorogenic acid treatment are all upregulated. Therefore, exogenous chlorogenic acid can significantly improve the color change effect of grape fruit. In addition, the determination of grape fruit quality indicators found that the exogenous application of chlorogenic acid increased the fruit weight, soluble solids content, soluble total sugar content and sugar-acid ratio of grape fruit, while reducing the titratable acid content, and improving the flavor and nutrient content of grape fruit.

[0009] Further preferably, the method of use is to prepare the chlorogenic acid into a chlorogenic acid aqueous solution, spray it during the grape fruit expansion period or the early color change period, and spray the solution on the crown and surrounding areas of the fruit until the solution naturally flows down the fruit surface.

[0010] Furthermore, the grape varieties are 'Cabernet Franc' and 'Kyoho'.

[0011] Furthermore, chlorogenic acid is used in plant growth promoters.

[0012] Furthermore, chlorogenic acid is used as a grape color change promoter.

[0013] Furthermore, chlorogenic acid is used in foliar fertilizer to promote color change.

[0014] The present invention has the following advantages / benefits: 1. The chlorogenic acid (CGA) used in the present invention is a polyphenol compound composed of caffeic acid and quinic acid. It is the main phenolic substance in the pulp of many fruits such as tomatoes, peaches, pears, strawberries and grapes. It is an important secondary metabolite and is safer than chemically synthesized hormones. The present invention promotes the application and development of chlorogenic acid in the ripening and quality of pre-harvest grape fruits, and solves the problems of fruit ripening agents currently on the market containing hormones, being expensive and potentially toxic.

[0015] 2. The experimental data of the present invention proves that the exogenous application of chlorogenic acid significantly increases the anthocyanin content of grape fruit. The detection results of the anthocyanin synthase gene expression levels show that the relative expression levels of anthocyanin synthase genes after exogenous chlorogenic acid treatment are all upregulated. Therefore, the exogenous application of chlorogenic acid can significantly improve the color change effect of grape fruit.

[0016] 3. In addition, the present invention determined the indicators of grape fruit and fruit quality and found that the exogenous application of chlorogenic acid increased the fruit weight, soluble solids content, soluble total sugar content and sugar-acid ratio of grape fruit, while reducing the titratable acid content, and improving the flavor and nutrient content of grape fruit. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the prior art descriptions. Obviously, the drawings described below are only one embodiment of the present invention, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0018] Figure 1 : The color change of one batch of wine grape 'Cabernet Franc' after being treated with chlorogenic acid at different concentrations.

[0019] Figure 2 : The color change (A) and anthocyanin content change (B) of the second batch of table grape 'Kyoho' after being treated with different concentrations of chlorogenic acid in the present invention; Figure 3 : The relative expression level of anthocyanin synthase gene in table grape 'Kyoho' 68 days after the second fruit flowering after being treated with 50 μM chlorogenic acid; Figure 4 : Effects of different concentrations of chlorogenic acid treatment on the fruit weight (A) and fruit shape index (B) of the second crop of table grape 'Kyoho'; Figure 5:The effects of the present invention on the soluble solid content (A), titratable acid (B), sugar-acid ratio (C) and soluble total sugar content (D) of the second fruit of table grape 'Kyoho' after treatment with different concentrations of chlorogenic acid; Figure 6 :The present invention treats one batch of table grape 'Kyoho' with 50 μM chlorogenic acid and changes in color change (A) and anthocyanin content (B); Figure 7 : The relative expression level of anthocyanin synthase gene in table grape 'Kyoho' 67 days after one fruit flowering after being treated with 50 μM chlorogenic acid; Figure 8 :The effect of the present invention on the single fruit weight (A) and fruit shape index (B) of the fresh-table grape 'Kyoho' after treatment with 50 μM chlorogenic acid; Fig. 9 :The effect of the present invention on the soluble solid content (A), titratable acid (B), sugar-acid ratio (C) and total soluble sugar content (D) of one batch of table grape 'Kyoho' after treatment with 50 μM concentration of chlorogenic acid; DETAILED DESCRIPTION The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. The following embodiments are only for illustrating the present invention, and are not intended to limit the scope of the present invention in any way. Based on the embodiments in the present invention, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present invention. The experimental methods used in the present invention are conventional methods unless otherwise specified. The materials, reagents, etc. used in the present invention, unless otherwise specified, can be obtained from commercial channels. In addition, other terms used in the present invention, unless otherwise specified, generally have the meanings commonly understood by those of ordinary skill in the art.

[0020] Example 1: Effect of exogenous chlorogenic acid on coloration of one crop of wine grape 'Cabernet Franc' 1. Experimental Materials Grape( Vitis vinifera L . ) The variety ‘Cabernet Franc’ was from Huadong Grape Bailey Winery, Qingdao (36°16′N, 120°51′E).

[0021] Chlorogenic acid (RQ524R320) was purchased from Shanghai Ruiyong Biotechnology Co., Ltd. (RYON, Shanghai).

[0022] 2. Experimental Methods 1) Material cultivation: The test materials are disease-free and uniformly growing grape plants, with a plant spacing of 1.5 m and a row spacing of 2 m. The "single-pole double-arm" cultivation rack is used. The soil is sandy loam with a soil layer of 40 cm to 70 cm. The lower layer is rock or clay, with a loose structure, convenient farming, moisture retention, and good soil fertility. During the growth period of the grapes, no pesticides are sprayed on them, and they grow and manage naturally until the fruits are ripe.

[0023] 2) Experimental treatment: Control group: Grape berries were sprayed with distilled water Treatment group 1: Grape berries were sprayed with 50 µM chlorogenic acid aqueous solution Treatment group 2: Grape berries were sprayed with 100 µM chlorogenic acid aqueous solution Treatment group 3: Grape berries were sprayed with 200 µM chlorogenic acid aqueous solution Treatment method: Select the 'Cabernet Franc' grape bunches with basically uniform growth and no disease or damage, and spray the grape bunches with different test groups at 46 days after flowering (46 DAF, expansion period). Spray once every 12 days, for a total of 4 times, with at least 3 replicates for each treatment, and observe the phenotype and take photos before each spraying.

[0024] 3. Experimental data 1) Effects of exogenous chlorogenic acid treatment on coloration of one crop of wine grape 'Cabernet Franc' In order to explore the role of chlorogenic acid in wine grapes, different concentrations of chlorogenic acid were sprayed on Cabernet Franc 46 days after flowering (46 DAF, swelling period). Figure 1 The results showed that the control group and the 200 µM chlorogenic acid sprayed fruit just started to change color 70 days after flowering, while the 50 µM and 100 µM chlorogenic acid sprayed fruit had mostly changed color 70 days after flowering, and the 50 µM concentration was the most obvious. It is speculated that the external application of chlorogenic acid can promote the color change of the first batch of wine grapes of Cabernet Franc, and the 50 µM chlorogenic acid treatment has the best effect.

[0025] Example 2: Effects of exogenous chlorogenic acid on coloration and fruit quality of second-harvest table grape 'Kyoho' 1. Experimental Materials Grape( Vitis vinifera L . ) Variety 'Kyoho' ( Vitis Labrusca × Vinifera 'Kyoho' ) The second crop of fruit was provided by farmers in Xing’an County, Guilin, Guangxi (25°61′N, 110°67′E).

[0026] Chlorogenic acid (RQ524R320) was purchased from Shanghai Ruiyong Biotechnology Co., Ltd. (RYON, Shanghai).

[0027] 2. Experimental Methods 1) Material cultivation: The test materials were disease-free and uniformly growing grape plants with a plant spacing of 1.5 m and a row spacing of 2 m. They were watered and fertilized regularly and managed according to normal field management methods throughout the growth cycle.

[0028] 2) Experimental treatment: Control group: Grape berries were sprayed with distilled water Treatment group 1: Grape berries were sprayed with 50 µM chlorogenic acid aqueous solution Treatment group 2: Grape berries were sprayed with 100 µM chlorogenic acid aqueous solution Treatment method: The experiment was conducted in Xing'an County, Guilin, Guangxi. The 'Kyoho' grape bunches with basically uniform growth and no disease or damage were selected. Different test groups were sprayed on the grape bunches 58 days after flowering (58 DAF, late expansion stage). The spraying was done once every 10 days, for a total of 3 times, and each treatment was repeated at least 3 times. Photos were taken and samples were taken before each spraying. Samples were taken on the 0th, 10th and 20th days after the start of the experiment. Fruits of uniform size were taken from the bunches at the upper, middle and lower parts of each plant. 300 fruits were taken from each experimental group to measure fruit quality and other related indicators.

[0029] 3) Determination of fruit quality indicators and other related indicators: Determination indicators: anthocyanin content, relative expression of anthocyanin synthase genes, fruit weight, fruit shape index, soluble solids content, titratable acid content, sugar-acid ratio, and soluble sugar content.

[0030] The anthocyanin content in grape fruit was detected by pH differential method (Wang Xin et al., 2020).

[0031] The sample RNA was extracted by the modified cetyltrimethylammonium bromide (CTAB) method according to the method of Li Xidong et al. (Li Xidong et al., 2011). The first strand of cDNA was synthesized by reverse transcription using the EasyScript One-StepgDNA Removal and cDNA Synthesis SuperMix reverse transcription kit of Beijing Quanshi Biotechnology Co., Ltd. according to the instructions. Quantitative primers were designed online based on the grape gene sequence in the NCBI database and the Primer-BLAST tool (Table 1). The quantitative primers were synthesized by Beijing Qingke Biotechnology Co., Ltd. The real-time fluorescence quantitative PCR reagent was selected from ArtiCan ATM SYBR qPCR Mix, system: 10 μL iQ TMSYBR Green Supermix, 2 μL cDNA, 0.4 μL upstream and downstream primers (10 μml / L), 7.2 μL ddH2O, reaction program: 95℃ pre-denaturation for 30 s; 95℃ denaturation for 30 s, 56℃ annealing for 30 s, 72℃ extension for 30 s, 45 cycles, each sample was repeated 3 times. VvActin The internal reference gene was used for standardization and calibration, and the data were analyzed using 2 -ΔΔCT Method for analysis.

[0032] Table 1 Primer sequences

[0033] The weight of each fruit was measured using an electronic balance (Mettler AE 200).

[0034] The horizontal and vertical diameters of grape fruits are measured with a vernier caliper (ABS digital vernier caliper). The ratio of the vertical diameter to the horizontal diameter of the fruit is calculated based on the fruit height and the fruit transverse diameter, i.e., the fruit shape index, according to the following formula: fruit shape index = vertical diameter / horizontal diameter.

[0035] The fruit hardness was measured using a fruit hardness meter (GY-1).

[0036] The soluble solids content of the fruit was determined using a PAL-1 saccharimeter.

[0037] The titratable acid content of the fruit was determined by acid-base titration (Yang Ximeng et al., 2024).

[0038] The soluble sugar content of the fruit was determined by anthrone colorimetry (Sun et al, 2018). The sugar-acid ratio of the fruit was calculated by combining the ratio of soluble solids to titratable acid. The calculation was performed according to the following formula: sugar-acid ratio = soluble solids / titratable acid.

[0039] 3. Experimental data 1) Effects of exogenous chlorogenic acid treatment on the coloration of the second batch of table grape 'Kyoho' 50 µM and 100 µM chlorogenic acid were sprayed on 'Jufeng' 58 days after flowering (58 DAF, late expansion stage). Figure 2 -A showed that the fruits in the control group changed color slightly 68 days after flowering, while most of the fruits sprayed with 50 µM and 100 µM chlorogenic acid changed color 68 days after flowering, and all of them changed color 78 days after flowering, which was significantly faster than the control group, and the most obvious change was at 50 µM.

[0040] The anthocyanin content was tested and the results were as follows Figure 2-B, it was found that compared with the control group, the anthocyanin content increased after chlorogenic acid treatment, and the most obvious was after 50 µM chlorogenic acid treatment. RT-qPCR experiments were performed on grape berries 68 days after flowering after 50 µM chlorogenic acid treatment to explore the effect of chlorogenic acid on anthocyanin synthase genes VxDV , VvF3'5'H2 , VdF , VxD and VxF The results showed that the relative expression levels of the above anthocyanin synthase genes were significantly upregulated ( Figure 3 ).

[0041] In conclusion, exogenous application of chlorogenic acid can promote the color change of the second batch of table grape 'Kyoho', and the effect of 50 µM chlorogenic acid treatment is the best.

[0042] 2) Effects of exogenous chlorogenic acid treatment on the second fruit weight and fruit shape index of table grape 'Kyoho' like Figure 4 As shown in the figure, compared with the control group, the fruit weight increased after chlorogenic acid treatment; the fruit shape index also changed. The fruit shape index ratio after treatment with 50 µM chlorogenic acid was closer to 1, and the fruit was fuller.

[0043] 3) Effects of exogenous chlorogenic acid treatment on soluble solids content and sugar and acid content in the second batch of table grape 'Kyoho' like Figure 5 As shown in the figure, compared with the control group, the soluble solid content of the grape fruit increased after chlorogenic acid treatment, and the 50 µM chlorogenic acid treatment group was the most obvious. The titratable acid content decreased, while the sugar-acid ratio and the soluble total sugar content increased.

[0044] In summary, the experimental data indicate that exogenous chlorogenic acid can enhance the flavor of grape berries and promote the quality of 'Kyoho' grape berries.

[0045] Example 3: Effects of exogenous chlorogenic acid on coloration and fruit quality of fresh-table grape 'Kyoho' 1. Experimental Materials Grape( Vitis vinifera L.) variety 'Kyoho' ( Vitis Labrusca × Vinifera 'Kyoho' ) from Baifu Road, Chengyang District, Qingdao City, Shandong Province (36°30′N, 120°49′E).

[0046] Chlorogenic acid (RQ524R320) was purchased from Shanghai Ruiyong Biotechnology Co., Ltd. (RYON, Shanghai).

[0047] 2. Experimental Methods 1) Material cultivation: The test materials were disease-free and uniformly growing grape plants with a plant spacing of 1 m and a row spacing of 1.5 m. They were watered and fertilized regularly and managed according to normal field management methods throughout the growth cycle.

[0048] 2) Experimental treatment: Control group: Grape berries were sprayed with distilled water Treatment group: Grape berries were sprayed with 50 µM chlorogenic acid aqueous solution Treatment method: After preliminary concentration screening in the laboratory, the optimal chlorogenic acid treatment concentration was determined to be 50 µM; with clean water treatment as the control, 6 replicates were set. A batch of 'Kyoho' grape bunches with basically consistent growth and no disease or harm were selected, and different test groups were sprayed on the grape bunches 43 days after flowering (43 DAF, expansion period). The solution was sprayed on the crown and around the fruit until the solution naturally flowed down on the fruit surface. Spray once every 7 days, for a total of 5 times, each time in the afternoon and evening, and the bunches were sprayed evenly and thoroughly, with droplets dripping on the bunches. At the same time, a small amount of leaves around the bunches were sprayed and bagged. Phenotypic observations and photos were taken every 5-7 days.

[0049] 3) Determination of fruit quality indicators and other related indicators: Determination indicators: anthocyanin content, relative expression of anthocyanin synthase genes, fruit weight, fruit shape index, soluble solids content, titratable acid content, sugar-acid ratio, and soluble sugar content.

[0050] The anthocyanin content in grape fruit was detected by pH differential method (Wang Xin et al., 2020).

[0051] The sample RNA was extracted by the modified cetyltrimethylammonium bromide (CTAB) method according to the method of Li Xidong et al. (Li Xidong et al., 2011). The first strand of cDNA was synthesized by reverse transcription using the EasyScript One-StepgDNA Removal and cDNA Synthesis SuperMix reverse transcription kit of Beijing Quanshi Biotechnology Co., Ltd. according to the instructions. Quantitative primers were designed online based on the grape gene sequence in the NCBI database and the Primer-BLAST tool (Table 1). The quantitative primers were synthesized by Beijing Qingke Biotechnology Co., Ltd. The real-time fluorescence quantitative PCR reagent was selected from ArtiCan ATM SYBR qPCR Mix, system: 10 μL iQ TMSYBR Green Supermix, 2 μL cDNA, 0.4 μL upstream and downstream primers (10 μml / L), 7.2 μL ddH2O, reaction program: 95℃ pre-denaturation for 30 s; 95℃ denaturation for 30 s, 56℃ annealing for 30 s, 72℃ extension for 30 s, 45 cycles, each sample was repeated 3 times. VvActin The internal reference gene was used for standardization and calibration, and the data were analyzed using 2 -ΔΔCT Method for analysis.

[0052] Table 1 Primer sequences

[0053] The weight of each fruit was measured using an electronic balance (Mettler AE 200).

[0054] The horizontal and vertical diameters of grape fruits are measured with a vernier caliper (ABS digital vernier caliper). The ratio of the vertical diameter to the horizontal diameter of the fruit is calculated based on the fruit height and the fruit transverse diameter, i.e., the fruit shape index, according to the following formula: fruit shape index = vertical diameter / horizontal diameter.

[0055] The fruit hardness was measured using a fruit hardness meter (GY-1).

[0056] The soluble solids content of the fruit was determined using a PAL-1 saccharimeter.

[0057] The titratable acid content of the fruit was determined by acid-base titration (Yang Ximeng et al., 2024).

[0058] The soluble sugar content of the fruit was determined by anthrone colorimetry (Sun et al, 2018). The sugar-acid ratio of the fruit was calculated by combining the ratio of soluble solids to titratable acid. The calculation was performed according to the following formula: sugar-acid ratio = soluble solids / titratable acid.

[0059] 3. Experimental data 1) Effects of exogenous chlorogenic acid treatment on coloration of fresh-table grape 'Kyoho' After concentration screening in Example 1 and Example 2, the optimal concentration of chlorogenic acid for external application was 50 μM. Therefore, in Example 3, 50 μM chlorogenic acid was used as the treatment group, and water was used as the control. Disease-free and harmless grape clusters in the expansion stage with consistent growth were selected at Baifu Road, Chengyang District, Qingdao City, Shandong Province for treatment, and each treatment was repeated 6 times. Figure 6 -A, the water treatment group slightly changed color 67 days after flowering, while most of the grapes changed color after being treated with 50 μM chlorogenic acid. It is speculated that chlorogenic acid can promote the color change of one batch of fresh-table grape 'Kyoho'.

[0060] like Figure 6-B, the anthocyanin content at each stage after chlorogenic acid treatment was detected. Compared with the control group, the anthocyanin content was significantly increased at 58 days, 67 days, and 76 days after flowering. RT-qPCR experiments were performed on grape berries treated with 50 mM chlorogenic acid 67 days after flowering to explore the effect of chlorogenic acid on anthocyanin synthase genes. VxDV , VvF3'5'H2 , VdF , VxD and VxF The results showed that the relative expression levels of the above anthocyanin synthase genes were significantly upregulated ( Figure 7 ).

[0061] In conclusion, exogenous chlorogenic acid can promote the color change of fresh-table grape 'Kyoho' in one batch, and the effect of 50 μM chlorogenic acid treatment is the best.

[0062] 2) Effects of exogenous chlorogenic acid treatment on fruit weight and fruit shape index of table grape 'Kyoho' like Figure 8 As shown in the figure, compared with the control group, the single fruit weight after chlorogenic acid treatment increased significantly at 58 days, 67 days, and 76 days after flowering ( Figure 8 -A); but had no effect on the fruit shape index ( Figure 8 -B).

[0063] 3) Effects of exogenous chlorogenic acid treatment on soluble solids content and sugar and acid content of fresh table grape 'Kyoho' fruit like Fig. 9 As shown in the figure, compared with the control group, the soluble solid content of grape berries treated with chlorogenic acid increased significantly ( Fig. 9 -A), the titratable acid content decreased ( Fig. 9 -B), while the sugar-acid ratio and total soluble sugar content increased significantly ( Fig. 9 -C and Fig. 9 -D).

[0064] The above results all indicate that exogenous chlorogenic acid may enhance the flavor of grape berries and promote the quality of 'Kyoho' grape berries.

[0065] In summary, the exogenous application of chlorogenic acid increased the anthocyanin content and the relative expression of anthocyanin synthase genes in the second-harvest fruit of Guangxi'Kyoho' fresh-eating grape, promoted the coloring of grape fruit, increased the fruit weight, soluble solids content, soluble total sugar content and sugar-acid ratio of grape fruit, and reduced the titratable acid content. The flavor and nutrient content of grape fruit are improved. According to the above results, it is speculated that a 50 µM aqueous solution of chlorogenic acid can promote the color change of the second-harvest fruit of fresh-eating grape 'Kyoho' and improve the quality of grape fruit. In addition, a 50 µM aqueous solution of chlorogenic acid can also promote the color change of the first-harvest fruit of Qingdao Chengyang fresh-eating grape 'Kyoho' and the first-harvest fruit of Qingdao Huadong wine grape 'Cabernet Franc'.

[0066] Therefore, exogenous application of chlorogenic acid can speed up the color change of multiple varieties of grapes, improve the quality of grape fruit, and promote the commodity rate of grapes and earlier market sales.

[0067] It is understandable that those skilled in the art can make equivalent substitutions or changes based on the technical solution and concept of the present invention, and all these changes or substitutions should fall within the protection scope of the claims attached to the present invention.

Claims

1. The application of chlorogenic acid in improving the quality of grape fruit, characterized in that: The dosage of chlorogenic acid is 50-200 μM in mass concentration; the method of use is to prepare the chlorogenic acid into a chlorogenic acid aqueous solution, and spray the grape fruit once every 7-12 days, and spray 3-6 times.

2. The use of chlorogenic acid in improving grape fruit quality according to claim 1, characterized in that: The optimal dosage of the chlorogenic acid is a mass concentration of 50 µM.

3. The use of chlorogenic acid in improving grape fruit quality according to claim 1, characterized in that: The method of use is to prepare the chlorogenic acid into a chlorogenic acid aqueous solution, spray it during the grape fruit expansion period or the late expansion period, and spray the solution on the crown and around the fruit until the solution flows down naturally on the fruit surface.

4. The use of chlorogenic acid in improving grape fruit quality according to claim 1, characterized in that: The grape varieties are 'Cabernet Franc' and 'Kyoho'.

5. Use of the chlorogenic acid according to any one of claims 1 to 4 in a plant growth promoter.

6. Use of the chlorogenic acid according to any one of claims 1 to 4 in a grape color change promoter.

7. Use of chlorogenic acid as described in any one of claims 1 to 4 in foliar fertilizer for promoting color change.

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