Application of Pongamia chinensis peel extract in mango preservation

Abstract

The invention discloses the application of a Pongamia chinensis peel extract in the preservation of mangoes. The Pongamia chinensis peel extract has a significant inhibitory effect on the growth of mango anthracnose bacteria, can reduce the decay rate of mangoes during storage, has no significant effect on the weight loss rate of mangoes during storage, can slow down the loss of vitamin C in mangoes during storage, and can significantly inhibit the softening of mangoes, inhibit the increase of soluble solids and the decrease of titratable acid during storage; and the raw material Pongamia chinensis used in the invention is a folk medicine in my country and India, with a wide source, large output and low cost.

Description

Technical Field

[0001] The invention belongs to the technical field of fruit preservation, and particularly relates to application of pongamia chinensis peel extract in mango preservation. Background Art

[0002] Mango is an important fruit in tropical and subtropical regions. It has a delicious taste and rich nutrition, and is known as the "King of Tropical Fruits". my country is the world's second largest mango producer and the largest mango consumer. As of 2020, the country's mango planting area reached 5.241 million mu, with a total output of 3.306 million tons and an output value of 20.52 billion yuan. Mango is a respiratory climacteric fruit. After picking, it will slowly soften at room temperature and cannot be stored in a household refrigerator at 4 degrees Celsius. This causes consumers to buy it and leave it for too long. It is very easy to soften or even rot, affecting consumption. Therefore, it is of great significance to conduct research on the room temperature preservation of mangoes and extend their shelf life.

[0003] Traditional preservation methods include pre-harvest γ-aminobutyric acid (GABA) treatment, plant essential oil fumigation treatment, chitosan coating treatment, chitosan coating plus antibiotic treatment, and 54 ℃ hot water soaking for 8 min combined with 0.5% chitosan coating. All of the above treatment methods can achieve good preservation effects, but they all have certain shortcomings, such as the high price of GABA treatment raw materials, the troublesome operation of chitosan coating, the high price of plant essential oils, and the harmfulness of antibiotic treatment to the human body and the environment. Therefore, it is necessary to find a safer and more environmentally friendly way to preserve mangoes.

[0004] Pongamia sutchuenensis Pongamia pinnata Pongamia merr. (L.) Merr.) is a semi-mangrove plant of the genus Pongamia in the Fabaceae family. It is widely distributed in coastal mudflats of Australia, India, Malaysia and southern my country. In my country and India, the whole plant, including roots, stems, leaves and fruits, can be used as medicine. It has a wide distribution area, a large pod yield, and has the characteristics of wind resistance, drought resistance, salt resistance, etc. The present invention intends to extract the effective ingredients in the pods of Pongamia merr. and use them for research on mango preservation. Summary of the invention

[0005] In order to solve the above defects, the technical problem to be solved by the present invention is to provide an application of Pongamia chinensis peel extract in the preservation of mangoes.

[0006] The above technical problem of the present invention can be achieved through the following technical solution: application of Pongamia chinensis peel extract in mango preservation.

[0007] As a preferred embodiment of the present invention, the Pongamia chinensis extract is prepared by the following method: taking Pongamia chinensis pods, crushing them to obtain Pongamia chinensis pod powder, soaking the Pongamia chinensis pod powder in ethyl acetate and performing ultrasound-assisted extraction, combining the filtrates, concentrating under reduced pressure to obtain an extract, and drying to obtain the Pongamia chinensis extract.

[0008] Furthermore, the Pongamia pod powder is soaked in ethyl acetate and extracted with ultrasound assistance, filtered, and the residue is repeatedly extracted until the extract does not change color, filtered, the filtrate is combined, concentrated under reduced pressure to an extract, vacuum frozen to dryness, and transferred to a desiccator for storage.

[0009] Optionally, the dosage relationship of the Pongamia pod powder and the ethyl acetate is 1 g: 3-5 mL, the soaking time is 30-60 min, and the ultrasound-assisted extraction time is 30 min.

[0010] Optionally, when the Pongamia affine extract is used, the Pongamia affine extract is diluted with ethanol having a volume percentage of more than 95% to a concentration of 0.01-0.08 g / mL.

[0011] The ethanol with a volume percentage of 95% or more refers to ethanol with a volume percentage of 95% to anhydrous ethanol.

[0012] Furthermore, when the Pongamia affine extract is used, the Pongamia affine extract is diluted with 95% by volume ethanol to a concentration of 0.06-0.08 g / mL.

[0013] Alternatively, the Pongamia serrata extract inhibits Colletotrichum truncatula during storage of mangoes.

[0014] Optionally, the use of the Pongamia peel extract of the present invention in the preservation of mangoes includes reducing the decay rate of mangoes during storage, inhibiting the loss of Vc during storage of mangoes, inhibiting the reduction of hardness during storage of mangoes, inhibiting the increase of soluble solids content during storage of mangoes, and inhibiting the reduction of titratable acid during storage of mangoes.

[0015] The present invention has the following advantages:

[0016] (1) The raw material Pongamia affine used in the present invention is a folk medicine in my country and India, with a wide source, large output and low cost;

[0017] (2) The Pongamia chinensis peel extract of the present invention has a significant inhibitory effect on the growth of mango anthracnose, can reduce the decay rate of mangoes during storage, has no significant effect on the weight loss rate of mangoes during storage, can also slow down the loss of vitamin C in mangoes during storage, and can significantly inhibit the softening of mangoes, and inhibit the increase of soluble solids and the decrease of titratable acid during storage. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is the inhibitory effect of the concentration of Pongamia chinensis extract in Example 1 on Colletotrichum mangoescens;

[0019] Figure 2The inhibition rate of the Pongamia chinensis extract on mango anthracnose varies with storage time in Example 1;

[0020] Figure 3 The effects of different treatment methods on the mango rot rate in Example 1;

[0021] Figure 4 The effects of different treatment methods on the weight loss rate of mango in Example 1;

[0022] Figure 5 The effects of different treatment methods in Example 1 on the Vc content of mango;

[0023] Figure 6 The effects of different treatment methods on mango hardness in Example 1 are shown;

[0024] Figure 7 The effects of different treatment methods on soluble solids in mango in Example 1;

[0025] Figure 8 The figure shows the effects of different treatment methods in Example 1 on titratable acid in mango. DETAILED DESCRIPTION

[0026] The experimental methods used in the following examples are conventional methods unless otherwise specified, and the materials, reagents, etc. used in the following examples are commercially available or can be prepared by existing methods unless otherwise specified. Example 1

[0027] 1.1 Preparation of Pongamia chinensis extract

[0028] Weigh 500 g of Pongamia pod powder, add 1500 mL of ethyl acetate and soak for 30 min, perform ultrasonic-assisted extraction for 30 min, filter, extract the residue repeatedly until the extract does not change color, filter, combine the filtrate, concentrate under reduced pressure to an extract, vacuum freeze-dry for 24 h, and store in a desiccator.

[0029] Weigh 2 g, 4 g, 6 g and 8 g of dry extract respectively, dissolve in 100 mL of 95% (v / v) ethanol to prepare extracts with concentrations of 2%, 4%, 6% and 8% (w / v) for later use.

[0030] 1.2 Inhibitory effect of the concentration of Pongamia chinensis extract on Colletotrichum mangoe

[0031] Mango Anthrax was collected from rotten mangoes in a mango orchard in Sanya and was identified as Mango Anthrax by plate isolation and identification ( Colletotrichum gloeosporioides), the inhibition rate was determined by mycelial growth rate. Prepare PDA medium (400g potato, 40g glucose, 40g agar), sterilize at 121℃ for 20min, wait until the temperature of the medium drops to about 55℃, add ethanol solutions of Pongamia affine extract of different concentrations, mix evenly, so that the final concentration of Pongamia affine extract in the medium is 50, 100, 200, 400, 800μg / mL, and pour into the culture dish. Add the same volume of 95% ethanol to the blank control group. Inoculate a 2mm diameter mango anthracnose agar block in the center of the culture dish, culture at 27℃, track and observe the growth of the colony, measure the colony diameter (cm) by the cross method, and calculate the inhibition rate according to the formula.

[0032] Relative inhibition rate (%) = colony diameter of control group - colony diameter of treatment group / colony diameter of control group * 100%

[0033] The results are as follows Figure 1-2 As shown, the extract solutions of P. chinensis treated with different concentrations inhibited the mycelial growth and expansion of Colletotrichum mangoense. The higher the concentration, the higher the inhibition rate. The extract with a concentration of 800 μg / mL had the highest inhibition on the second day, reaching 88.46%, which was significantly higher than other concentrations (P < 0.05) and had a more significant inhibitory effect.

[0034] Therefore, the Pongamia chinensis peel extract of the present invention has a significant inhibitory effect on mango anthracnose and can be used in the preservation of mangoes.

[0035] 1.3 Effect of Pongamia chinensis extract on mango rot rate

[0036] Several mangoes with the same maturity were selected and coated with 0%, 2%, 4%, 6%, and 8% of Pongamia odorata extract and 95% ethanol using a brush, dried in the shade at room temperature, and stored at 28°C (relative humidity 70-80%) for 8 days. Figure 1 No treatment was performed on the blank in the table. On the 8th day, the mango fruit decay was checked and evaluated according to the determination criteria of Huang Yumi et al. (2021). The evaluation criteria are as follows:

[0037] Rot rate (%) = [∑ (rot grade × number of fruits at that grade) / (highest grade × total number of fruits)] × 100.

[0038] Table 1 Mango fruit decay rate classification standard

[0039] Degree of decay Evaluation criteria 0 No lesions on the fruit surface 1 There are small spots on the surface of the fruit 2 Fruit surface rot area ≤ 20% 3 The fruit surface rot area is between 20% and 50% 4 Fruit surface rot area ≥50%

[0040] The results of decay rate are as follows Figure 3As shown in the figure, the decay rates of the four groups of mangoes were significantly different, among which the decay rate of the 95% ethanol treatment was the highest, nearly 60%, followed by the blank control and the 6% Pongamia extract treatment group, and the 8% Pongamia treatment group had the lowest decay rate, only 20%. It can be seen that Pongamia extract can significantly reduce the decay rate of mangoes, improve its quality and extend its shelf life. Ethanol itself has almost no bactericidal effect on fungi. Spraying mangoes with ethanol may also kill bacteria on the surface of mangoes that have antagonistic effects on anthrax, which is more conducive to the growth of fungi. At the same time, 95% ethanol is very volatile, and the remaining water after evaporation provides a natural environment for the growth of fungi. Therefore, the decay rate of mangoes treated with 95% ethanol is higher than that without any treatment.

[0041] Since the 2% and 4% Pongamia chinensis extract treatment groups had poor effects, the following article took 6% and 8% as examples to further study the effects of Pongamia chinensis extract on mango weight loss rate, Vc content in mango, mango hardness, mango soluble solids and titratable acid in mango.

[0042] 1.4 Effect of Pongamia odorata extract on mango weight loss rate

[0043] The treatment method of mango is the same as above, and the weight loss rate of mango is measured at different times. The method for measuring the weight loss rate of mango adopts the weighing method, and the weight of the fruit before and after the preservation treatment is taken. Weight loss rate (%) = [(weight before treatment - weight after treatment) / weight before treatment] × 100%

[0044] like Figure 4 As shown in the figure, the weight loss rate of mango increased with the extension of storage time, but there was no significant difference among the treatment groups at different times. Compared with the control, the Pongamia peel extract had no significant effect on the weight loss rate of mango during storage.

[0045] 1.5 Effect of Pongamia chinensis peel extract on the content of vitamin C in mango

[0046] The processing method of mango was the same as above, and the Vc content in mango was determined at different times. 0.5g of mango was taken, 5mL of 20g / L metaphosphoric acid was added, and ground in an ice bath. The grinding solution was centrifuged at 10000rpm for 5 minutes at 4°C, and the supernatant was taken and made up to 10mL with the above metaphosphoric acid solution, filtered with a filter membrane, and analyzed by HPLC.

[0047] The vitamin C content of fruits decreases as they mature during storage, so the vitamin C content of fruits also represents their freshness. Figure 5As shown in the figure, the Vc content in mango gradually decreased with the extension of storage time. The blank control and ethanol treatment had the largest decrease, followed by the 6% Pongamia extract treatment group, and the 8% Pongamia extract treatment group had the smallest decrease in Vc content, and its Vc content was significantly higher than that of other treatment groups after storage. The above results show that Pongamia extract can significantly inhibit the loss of Vc in mango during storage.

[0048] 1.6 Effect of Pongamia chinensis extract on mango firmness

[0049] The processing method of mangoes was the same as that of Example 1, and the hardness of mangoes was measured at different times. Five mangoes were selected from each treatment group, each fruit was peeled at the positive and negative equatorial positions of the mango, and then two positions were selected to measure the hardness of the fruit using a GY-3 hardness tester, and the average of the 10 measured values ​​was used as one test.

[0050] P=N / S

[0051] Where: P-hardness value of the fruit being tested (Kg / cm 2 or Kgf)

[0052] N-The weight of the force spring pressing on the fruit, Kg

[0053] S-force-bearing area of ​​the fruit, square meters or square centimeters

[0054] During storage, the hardness of the fruit gradually decreases as it matures, that is, the more ripe it is, the softer it becomes, and then it rots and deteriorates. Therefore, the hardness of the fruit is a representation of its freshness. Figure 6 As shown in the figure, with the extension of storage time, the hardness of mangoes gradually decreased. On the second, fourth and eighth days of storage, the hardness of mangoes in the 6% and 8% Pongamia extract treatment groups was significantly higher than that in the ethanol treatment group and the blank group. On the sixth day, the hardness of mangoes in the Pongamia extract treatment group was higher than that in the other two groups, but there was no significant difference.

[0055] 1.7 Effect of Pongamia chinensis peel extract on soluble solids in mango

[0056] For each mango after the fruit hardness is measured, take the pulp from the equator on both sides, cut it into small pieces, mash it, filter it with two layers of gauze, and squeeze out the juice. The soluble solid content is based on the national food safety standard "Determination of soluble solid content of fruits and vegetables-refractometer method" NY / T 2637-2014. Each fruit is measured twice, and the average of 10 measured values ​​is taken as one replicate, and each treatment is repeated 3 times.

[0057] The soluble solids in fruits decrease as they mature, so the decrease in soluble solids marks the increase in fruit maturity. Figure 7As shown, in all experimental groups in this embodiment, the soluble solid content first increased and then tended to be stable. Under the same storage time, the soluble solid content in mangoes in the 6% and 8% Pongamia serrata extract treatment groups was lower than that in the ethanol group and the blank group.

[0058] 1.8 Effect of Pongamia odorata Extract on Titratable Acidity in Mango

[0059] During the post-harvest ripening and aging process of the fruit, organic acids as respiratory substrates will be used in the tricarboxylic acid cycle, resulting in the consumption of organic acids, and the content will gradually decrease. Therefore, the reduction in organic acid content represents an increase in the maturity of mangoes. In this embodiment, the organic acid content is characterized by titratable acid. The measurement of titratable acid in mangoes is based on the first method in the national food safety standard "Determination of total acid in food" GB 12456-2021: acid-base indicator titration method. The results are as follows Figure 8 As shown, the titratable acid content in the four groups of mangoes (the processing method of mangoes is the same as that in Example 1) has a decreasing trend with the extension of storage time. The decrease in titratable acid content in the blank control is the most obvious, followed by the ethanol treatment group, and the 6% and 8% Pongamia odorata extract treatment groups have the smallest decrease. That is, the Pongamia odorata extract can significantly inhibit the decrease in the titratable acid content in mangoes and inhibit the ripening of mangoes.

[0060] Therefore, the Pongamia peel extract can be applied on the surface of tropical fruits such as mangoes by spraying or coating to be used as a preservative, or the Pongamia peel extract can be used together with other preservative ingredients to increase the preservation effect of mangoes.

[0061] The above implementation examples have been described in detail the different implementation processes of the present invention, but the implementation methods of the present invention are not limited thereto. Ordinary technicians in the relevant technical field can achieve the purpose of the present invention based on the contents disclosed in the present invention. Any improvements and modifications based on the concept of the present invention fall within the protection scope of the present invention, and the specific protection scope shall be subject to the claims.

Claims

1. Application of Pongamia chinensis peel extract as the only active ingredient in mango preservation; The application includes reducing the decay rate of mangoes during storage, inhibiting the loss of Vc during storage, inhibiting the reduction of hardness during storage, inhibiting the increase of soluble solid content during storage, and inhibiting the reduction of titratable acid during storage of mangoes by using the pongamia peel extract; The Pongamia chinensis extract is prepared by the following method: weighing 500 g of Pongamia chinensis pod powder, adding 1500 mL of ethyl acetate to soak for 30 minutes, ultrasonic-assisted extraction for 30 minutes, filtering, repeatedly extracting the residue until the extract does not change color, filtering, combining the filtrate, concentrating under reduced pressure to an extract, vacuum freeze-drying for 24 hours, and transferring to a desiccator for storage; When the Pongamia affine extract is used, the Pongamia affine extract is diluted with ethanol having a volume percentage of more than 95% to prepare a concentration of 0.06-0.08 g / mL.

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