Application of octacosanol in preservation of apple fruits

Abstract

The invention discloses an application of octacosanol in preservation of apple fruits. The invention discloses application of octacosanol in preservation of apple fruits, the application range of octacosanol is expanded, octacosanol is long-chain fatty alcohol naturally existing in plant epidermis wax, toxicity to human bodies and the environment is extremely low, and the octacosanol can be used in a reasonable concentration range, so that the octacosanol has a good preservation effect on apple fruits. The apple preservative has no adverse effect on apple fruit preservation and human health, meets the safety standard of food contact substances, is easy to degrade in the natural environment, does not cause environmental pollution, and is more environment-friendly compared with a traditional chemical preservative; the octacosanol aqueous solution is used for treating the apple fruits, so that the reduction of fruit hardness and cellulose content in the fruit storage period can be remarkably inhibited, and the conversion of original pectin to soluble pectin is inhibited; meanwhile, the activity of superoxide dismutase and catalase of the fruits is improved, and the oxidation resistance of the fruits is enhanced.

Description

Technical Field

[0001] The invention relates to the technical field of fruit preservation, and in particular to application of octacosanol in apple fruit preservation. Background Art

[0002] Apple (Malus domestica) is a fruit widely cultivated around the world and belongs to the genus Malus in the family Rosaceae. Apples are loved by people for their rich nutritional value, refreshing taste and various uses (such as fresh eating, baking, juice, etc.). The hardness and taste of apples change during the ripening process, which is closely related to the ingredients in the fruit. For example, the ratio and structural changes of cellulose, protopectin and soluble pectin play a decisive role in the texture of apples. As apples ripen, protopectin gradually transforms into soluble pectin, and the flesh becomes softer and has a more delicate taste. In addition, antioxidant enzymes in apples (such as superoxide dismutase and catalase) play an important role in the physiological processes of the fruit. These enzymes help slow down the oxidation process and protect apples from damage by free radicals, thereby delaying aging and maintaining freshness.

[0003] Postharvest loss of fruit refers to the quality decline and yield loss of fruit after picking due to physiological, physical, chemical or biological factors. These losses not only affect the appearance, taste and nutritional value of the fruit, but may also lead to food safety issues. Postharvest loss usually includes phenomena such as fruit decay, aging, dehydration, browning, and nutrient loss, which seriously affect market supply and consumer experience. Preservatives play an important role in food preservation. They can extend the shelf life of food and maintain the appearance and flavor of food. However, existing chemical preservatives have some drawbacks, which has prompted people to seek safer and more environmentally friendly alternatives. Among them, biological preservatives, as a new type of preservation method, have gradually gained attention and application.

[0004] Octacosanol (C28) is commonly found in natural waxes of plants, including wheat leaves, sugar cane, rice bran, etc. Toxicity studies have shown that the LD50 (lethal dose for 50% of subjects) of octacosanol in rats is 18000 mg kg -1 (Oral), much higher than salt (LD50 = 3000 mg kg -1). As a natural alcohol, it has good biodegradability and is easily absorbed and utilized by animals. Studies have shown that octacosanol has anti-Parkinson's effects, can regulate lipid and glucose metabolism, reduce fatigue, promote cardiovascular health, and has a protective effect on the liver. In addition, octacosanol can relieve constipation, has anti-inflammatory properties, and provides protection against various injuries. Given its potential health benefits, octacosanol is widely used as a dietary and pharmaceutical supplement, as well as an animal feed additive. Since organisms can usually only obtain limited amounts of octacosanol from a normal diet, the addition of sufficient doses of octacosanol may be beneficial to overall health. However, the application of octacosanol has mainly focused on its biomedical effects, and little is known about its effectiveness in preserving fruits and vegetables. Summary of the invention

[0005] In view of the above prior art, the purpose of the present invention is to provide an application of octacosanol in the preservation of apple fruit. The present invention uses an octacosanol aqueous solution to soak apples, which can significantly maintain the hardness, cellulose, and protopectin content of the apple fruit, reduce the soluble pectin content, and increase the superoxide dismutase activity and catalase activity, with good preservation effect and safety.

[0006] To achieve the above object, the present invention adopts the following technical solution:

[0007] The first aspect of the present invention provides the use of octacosanol in fruit preservation.

[0008] Preferably, the fruit is apple.

[0009] Preferably, the octacosanol achieves fruit preservation through at least one of the following (1)-(4):

[0010] (1) Inhibit the reduction of fruit firmness during storage;

[0011] (2) inhibit the decrease of cellulose content in fruits during storage;

[0012] (3) Inhibit the conversion of protopectin to soluble pectin during fruit storage;

[0013] (4) Improve the antioxidant capacity of fruits during storage.

[0014] Preferably, the improving the antioxidant capacity of the fruit during storage is specifically improving the superoxide dismutase activity and catalase activity during fruit storage.

[0015] A second aspect of the present invention provides a method for preserving apple fruits, comprising the following steps:

[0016] The apple fruits were soaked in an octacosanol aqueous solution, dried and stored at 15-25°C away from light.

[0017] Preferably, the concentration of the octacosanol aqueous solution is 0.5-5 mg·L -1 , soaking time 6-18h.

[0018] Beneficial effects of the present invention:

[0019] The invention discloses the application of octacosanol in the preservation of apple fruits, and expands the application scope of octacosanol. Octacosanol is a long-chain fatty alcohol naturally existing in plant epidermal wax, has extremely low toxicity to human body and environment, has no adverse effect on the preservation of apple fruits and human health when used within a reasonable concentration range, meets the safety standard of food contact substances, is easily degraded in the natural environment, does not cause environmental pollution, and is more environmentally friendly than traditional chemical preservatives. Using an octacosanol aqueous solution to treat apple fruits can significantly inhibit the reduction of fruit hardness and cellulose content during fruit storage, and inhibit the conversion of protopectin to soluble pectin; at the same time, the superoxide dismutase and catalase activities of the fruits are improved, and the antioxidant capacity of the fruits is enhanced. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 :0.5mg·L -1 Phenotypes of apple fruits after treatment with octacosanol and distilled water;

[0021] Figure 2 :0.5mg·L -1 Changes in firmness of Red Star apples under treatments of octacosanol and distilled water;

[0022] Figure 3 :0.5mg·L -1 Changes of cellulose in red star apple under treatments of octacosanol and distilled water;

[0023] Figure 4 :0.5mg·L -1 Changes of Red Star Apple Pectin under Treatments of Octacosanol and Distilled Water;

[0024] Figure 5 :0.5mg·L -1 Changes of soluble pectin in Red Star apples treated with octacosanol and distilled water;

[0025] Figure 6 :0.5mg·L -1 Changes in superoxide dismutase activity of Red Star apple under treatments of octacosanol and distilled water;

[0026] Figure 7 :0.5mg·L -1 Changes in catalase activity of Red Star apple under treatments of octacosanol and distilled water. DETAILED DESCRIPTION

[0027] It should be noted that the following detailed descriptions are illustrative and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0028] As described in the background technology, after harvesting, fruits often soften, deteriorate, change taste and lose water due to their own physiological activities and the physical and chemical factors of the external environment. Although the use of chemical preservatives in large quantities can extend the shelf life, it may cause pesticide residues, thereby endangering human health. Octacosanol, as a natural alcohol, has good biodegradability, is easily absorbed and utilized by animals, has anti-Parkinson's effect, can regulate lipid and glucose metabolism, reduce fatigue, promote cardiovascular health, and has a protective effect on the liver. However, the application of octacosanol is mainly concentrated on its biomedical effects, and little is known about its effectiveness in preserving fruits and vegetables.

[0029] Based on this, the inventors conducted a systematic study on the role of octacosanol in fruit preservation. By soaking red star apples in octacosanol solution, the effects on physiological indicators such as fruit hardness, cellulose, protopectin, soluble pectin, superoxide dismutase and catalase were investigated. The results showed that octacosanol can significantly inhibit the reduction of fruit hardness and cellulose content during fruit storage, and inhibit the conversion of protopectin to soluble pectin; at the same time, octacosanol can also significantly increase the activity of superoxide dismutase and catalase in fruits, and enhance the antioxidant capacity of fruits. In summary, octacosanol shows broad application potential in extending storage period and shelf life.

[0030] In order to enable those skilled in the art to more clearly understand the technical solution of the present application, the technical solution of the present application will be described in detail below in conjunction with specific embodiments.

[0031] The test materials used in the examples of the present invention are all conventional test materials in the art and can be purchased through commercial channels.

[0032] Embodiment 1: A method for preserving apple fruit

[0033] Prepare 0.5mg·L -1 The apples were soaked in an aqueous solution of octacosanol for 12 h, then placed in a dark place to dry naturally at room temperature, and stored at 20°C away from light.

[0034] Embodiment 2: A method for preserving apple fruit

[0035] Prepare 1mg·L -1The apples were soaked in an aqueous solution of octacosanol for 12 h, then placed in a dark place to dry naturally at room temperature, and stored at 20°C away from light.

[0036] Embodiment 3: A method for preserving apple fruit

[0037] Prepare 3mg·L -1 The apples were soaked in an aqueous solution of octacosanol for 12 h, then placed in a dark place to dry naturally at room temperature, and stored at 20°C away from light.

[0038] Embodiment 4: A method for preserving apple fruit

[0039] Prepare 5mg·L -1 The apples were soaked in an aqueous solution of octacosanol for 12 h, then placed in a dark place to dry naturally at room temperature, and stored at 20°C away from light.

[0040] Test example:

[0041] 1.1. Test method:

[0042] 1.1 Experimental Grouping:

[0043] A total of 200 Red Star apple fruits (each weighing 255.13 g ± 30.45 g) from the same batch, with the same specifications and no difference in freshness and other indicators were selected and randomly divided into two groups, with 100 fruits in each group.

[0044] The test group treated apple fruits in the manner of Example 1;

[0045] The control group used distilled water to soak the apples for 12 hours, then placed them in a dark place to dry naturally at room temperature and stored at 20°C away from light.

[0046] Apple samples were collected on days 0, 5, 10, 15 and 20 after treatment to observe apple phenotypes, and to measure apple firmness, cellulose, protopectin, soluble pectin, superoxide dismutase activity and catalase activity.

[0047] 1.2 Test method:

[0048] 1.2.1 Hardness determination method:

[0049] The firmness of apples was determined using a Stable Micro Systems TA.XT plus texture analyzer. A P / 2 cylindrical probe (2 mm in diameter) was used for the measurement, and the speed before the measurement was 2 mm·s -1 , measuring speed is 1 mm·s -1 , the speed after measurement is 5 mm·s -1, the penetration depth is 10mm, and the minimum perception is 10g. Fifteen apples are randomly selected from each group on each sampling day, and four points evenly dispersed and equally spaced around the central equator of the apple are randomly selected for puncture measurement perpendicular to the fruit surface. The measured fruit hardness values ​​are analyzed using the Texture Exponent 32 software. The hardness results of each apple are taken as the average of the four points, and the test results are taken as the average of the sampled apples.

[0050] 1.2.2 Cellulose determination method:

[0051] The cellulose content was determined using a cellulose content assay kit (Solarbio, Beijing, China).

[0052] (1) Extraction of cell wall material (CWM):

[0053] ① Weigh about 0.3 g (denoted as W1) of sample, add 1 mL of extracting solution 1, quickly homogenize at room temperature, incubate in a 90°C water bath for 20 min, cool to room temperature, centrifuge at 6000 g, 25°C for 10 min, and discard the supernatant.

[0054] ② Wash the precipitate twice with 1.5 mL of extraction solution 1 and acetone respectively (vortex oscillation for about 2 minutes, centrifuge at 6000g, 25℃ for 10 minutes, and discard the supernatant). The precipitate is the crude cell wall.

[0055] ③ Add 1 mL of Extract 2 (to remove starch) to the crude cell wall and soak for 15 hours. Centrifuge at 6000 g and 25 °C for 10 min, discard the supernatant, wash the precipitate twice with distilled water (vortex oscillation for about 2 min, centrifuge at 6000 g and 25 °C for 10 min, discard the supernatant), then dry the precipitate (at 60-100 °C) to obtain cell wall material (CWM), weigh it and record it as W2.

[0056] (2) Extraction of cellulose:

[0057] ① Weigh about 5 mg of dried CWM (recorded as W3), add 0.5 mL of distilled water to fully homogenize, transfer the homogenate to an EP tube, and dilute to 0.5 mL with distilled water.

[0058] ② Place the homogenate after volume adjustment in an ice-water mixture, slowly add 0.75 mL of concentrated sulfuric acid, slowly mix, and place in an ice-water bath for 30 minutes. Centrifuge at 8000g, 4°C for 10 minutes, take the supernatant, dilute 20 times with distilled water, and then test.

[0059] (3) Measurement steps

[0060] ① Preheat the spectrophotometer / enzyme reader for more than 30 minutes, adjust the wavelength to 620nm, and zero the spectrophotometer with distilled water.

[0061] ② 10mg·mL -1 The standard solution was diluted with distilled water to 0.125, 0.0625, 0.03125, 0.015625, 0.0078, 0.0039 mg·mL -1 The standard solution is kept aside.

[0062] ③Standard dilution table

[0063]

[0064] ④ Operation table (in 1.5mL centrifuge tube):

[0065] Reagent Name (μL) Determination tube Standard tube Blank tube sample 150 Standard solution 150 Distilled water 150 Working fluid 35 35 35 Concentrated sulfuric acid 315 315 315

[0066] Mix well, place in a 95℃ water bath for 10 min (cover tightly to prevent water loss), take out and cool to room temperature, draw 200μL into a 96-well plate or a micro-glass cuvette to measure the absorbance value A at 620nm, record them as A measurement tube, A standard tube, A blank tube respectively. Calculate ΔA = A measurement tube - A blank tube, ΔA standard = A standard tube - A blank tube (blank tube and standard curve only need to be tested 1-2 times).

[0067] Cellulose (mg g -1 mass) = x × V × 20 × (W2 / W3) / W1 / 1.11 = 22.52 × x × W2 / W3 / W1

[0068] 1.11: is the constant for converting the glucose content measured by this method into the cellulose content, that is, the color of 111μg glucose with anthrone reagent is equivalent to the color displayed by 100μg cellulose with anthrone reagent; V: volume of cellulose extract, 1.25mL (0.5mL distilled water + 0.75mL concentrated sulfuric acid); 20: sample dilution multiple; W1: sample mass, 0.3g; W2: sample cell wall material (CWM) mass, g; W3, cell wall material (CWM) mass weighed when extracting cellulose, g. The results of each test group are the average of 6 apples.

[0069] 1.2.3 Determination method of protopectin:

[0070] The original pectin content was determined using a proto-pectin assay kit (YGJ-2-G, Ke Ming, Suzhou, China).

[0071] (1) Weigh 0.05 g of apple sample, put it into a mortar, add 1 mL of extract solution 1, and grind it quickly. Transfer all the slurry into a 2 mL centrifuge tube, tighten the centrifuge tube, and place it in a 90°C water bath for 30 min. Cool it, and centrifuge it at 5000 × g and 25°C for 10 min. Aspirate and discard the supernatant, and retain the precipitate.

[0072] (2) Pipette 1 mL of the extract and add it to the precipitate. Fasten the centrifuge tube, place in a 90°C water bath for 30 min, cool, and centrifuge at 5000 g and 25°C for 10 min. Pipette and discard the supernatant and retain the precipitate.

[0073] (3) Pipette 1 mL of extract 2 and add it to the precipitate. Incubate in a 90°C water bath for 1 h. Cool and centrifuge at 8000 g and 25°C for 15 min. Keep the supernatant for testing.

[0074] (4) Sample addition table:

[0075]

[0076] (5) Mix thoroughly and transfer into a 1 mL glass cuvette. Measure the absorbance at 530 nm using a UV spectrophotometer. Read the absorbance of the blank tube, standard tube, control tube, and test tube. Record the absorbance values ​​as A1, A2, A3, and A4, respectively.

[0077] (6) Protopectin content (mg g -1 )=0.25×ΔA2 / ΔA1 / W

[0078] ΔA1=A2-A1; ΔA2=A4-A3; W: sample fresh weight (g).

[0079] The results of each test group were taken as the average of 6 apples.

[0080] 1.2.4 Soluble pectin determination method:

[0081] The content of pectin was determined using a water-soluble pectin assay kit (WSP-2-Y, Keming, Suzhou, China).

[0082] (1) Weigh 0.3 g of apple sample, put it into a mortar, add 1 mL of 80% ethanol, grind it quickly, transfer all the slurry into a 2 mL centrifuge tube, and fasten the centrifuge tube.

[0083] (2) Incubate in a 95°C water bath for 20 min, cool, and centrifuge at 4000 g at 25°C for 10 min. Discard the supernatant and retain the precipitate.

[0084] (3) Wash the precipitate once with 1.5 mL of 80% ethanol and once with acetone (vortex for 2 min, centrifuge at 4000 g, 25°C for 10 min, and save the precipitate).

[0085] (4) Pipette 1 mL of reagent 1 and add it to the precipitate. Let it soak for 15 hours. Centrifuge at 4000 g, 25°C for 10 min. Pipette and discard the supernatant and keep the precipitate.

[0086] (5) Place the precipitate in an oven at 65°C to dry and weigh it.

[0087] (6) Weigh 3 mg of the precipitate, put it into a mortar, add 1 mL of Reagent 2, and grind it quickly. Transfer the homogenate into a 1.5 mL centrifuge tube and centrifuge it at 8000 g at 4°C for 10 min. Take the supernatant for testing.

[0088] (7) Preheat the UV spectrophotometer for 30 min, set the wavelength to 530 nm, and use ddH 2 Adjust to zero with O; before using reagents 3 and 4, place them in a 37°C water bath for more than 10 minutes.

[0089] (8) Sample addition table:

[0090]

[0091] (9) Mix well, incubate in a 95℃ water bath for 5 min, and read the absorbance of the blank tube, standard tube, control tube, and test tube at 530 nm using a UV spectrophotometer. The absorbance values ​​are recorded as A1, A2, A3, and A4, respectively. If A is greater than 2, the sample to be tested needs to be diluted with ddH 2 O dilution (can be diluted 10 times or 20 times). Set up one blank tube and one standard tube, and set up one control tube for each test tube.

[0092] (10) Calculation formula: Soluble pectin content (mg·g -1 )=0.05×(A4-A3) / (A2-A1) / W×dilution factor; W: sample dry weight, g.

[0093] The results of each test group were taken as the average of 6 apples.

[0094] 1.2.5 Superoxide dismutase assay method:

[0095] (1) Weigh 0.5 g of the mixed apple sample and add 1 mL of phosphate buffer (0.05 mol·L -1 , pH = 7.8), add 1 mL of phosphate buffer after grinding in an ice bath, pour into a centrifuge tube, then wash the mortar with 2 mL of phosphate buffer, pour into a centrifuge tube, balance, centrifuge at low temperature for 20 min, and take the supernatant after centrifugation and refrigerate.

[0096] (2) Take test tubes of the same model, add 50 μL of supernatant (add 50 μL of phosphate buffer to each of the 4 control test tubes), add 3 mL of reaction solution to each test tube, place 2 control test tubes in the dark, and react the remaining tubes under 4000 lx sunlight for 20-30 min (the light conditions of each tube must be consistent, the higher the temperature, the shorter the time, and the lower the temperature, the longer the time). After the reaction is completed, use the control test tube without light as a blank, and measure the absorbance value at 560 nm colorimetrically.

[0097] (3) 150 mL reaction solution composition: water 12.7 mL, phosphate buffer 76.5 mL, Met 15.25 mL, NBT 15.25 mL, EDTA-Na 2 15.25mL, riboflavin 15.25mL.

[0098] (4) Calculation formula: The amount required to inhibit the photochemical reduction of NBT by 50% is the enzyme activity unit (U);

[0099] SOD activity (U·g -1 FW)=(A ck -A s )×V / (A ck ×0.5×FW×V 1 ).

[0100] A ck : Absorbance of the illumination control tube; A s : is the absorbance of the sample tube; V: is the total volume of the sample (mL); V 1 : The amount of sample used in the measurement (mL); FW: The weight of apple (g).

[0101] The results of each test group were taken as the average of 6 apples.

[0102] 1.2.6 Catalase assay method:

[0103] (1) Weigh 0.5 g of the mixed apple sample and add 1 mL of phosphate buffer (0.05 mol·L -1 , pH = 7.8), add 1 mL of phosphate buffer after grinding in an ice bath, pour into a centrifuge tube, then wash the mortar with 2 mL of phosphate buffer, pour into a centrifuge tube, balance, centrifuge at low temperature for 20 min, and take the supernatant after centrifugation and refrigerate.

[0104] (2) Take 100 μL of the supernatant and add it to a cuvette (add 100 μL of phosphate buffer for control), add 3 mL of reaction solution, immediately read the OD value at 240 nm and start timing, reading every 1 minute (read the OD value at 0, 1, 2, and 3 min).

[0105] (3) Preparation of reaction solution:

[0106] ①0.1 mol·L -1 20 mL of phosphate buffer with pH = 7.0, add 0.1 mol·L -1 Mix 5mL of hydrogen peroxide and set aside.

[0107] ②0.1 mol·L -1 Preparation of hydrogen peroxide: Take 568μL of 30% hydrogen peroxide in a 100mL volumetric flask, dilute to the mark with distilled water, shake well and set aside.

[0108] (4) Calculation formula: CAT total activity (△OD 240 ·min -1 ·g -1 FW)=(△OD 240 ×V) / (a×W×t)

[0109] V=4mL; a=0.1mL; W=0.5g; t=0.1min.

[0110] The results of each test group were taken as the average of 6 apples.

[0111] 1.3 Test results:

[0112] The test results are shown in Figure 1-Figure 7 .

[0113] Figure 1 This is the apple phenotype diagram with the best fruit condition. Figure 1 It can be seen that at 20 days, compared with the control group (0 mg·L -1 ) delayed fruit yellowing compared with fruits treated with octacosanol.

[0114] Figure 2 0.5mg·L -1 Changes in firmness of Red Star apples treated with octacosanol and distilled water. Figure 2 It can be seen that on the 15th and 20th days of storage, the firmness of the red star apples treated with octacosanol was significantly higher than that of the control group, indicating that octacosanol can effectively maintain the firmness of the fruit during storage.

[0115] Figure 3 0.5mg·L -1 Changes in cellulose content of Red Star apples treated with octacosanol and distilled water. Figure 3 It can be seen that on the 15th and 20th days of storage, the cellulose content of red star apples treated with octacosanol was significantly higher than that of the control group, indicating that octacosanol can effectively maintain the firmness of the fruit during storage.

[0116] Figure 4 and Figure 5 0.5mg·L -1 Changes of protopectin and soluble pectin in Red Star apples treated with octacosanol and distilled water. Figure 4 and Figure 5 As can be seen from the data, on the fifth day of storage, the original pectin of Red Star Apple treated with octacosanol was significantly higher than that of the control group, and the soluble pectin was significantly lower than that of the control group, indicating that octacosanol effectively inhibited the conversion of original pectin to soluble pectin.

[0117] Figure 6 and Figure 7 0.5mg·L -1Changes in superoxide dismutase activity and catalase activity of Red Star apple under treatment with octacosanol and distilled water. Figure 6 and Figure 7 As can be seen from the results, octacosanol treatment increased the superoxide dismutase activity and catalase activity in Red Star apples, enhancing the antioxidant capacity of the fruit. Based on the above experiments, it can be clearly seen that 0.5 mg·L -1 Apples treated with octacosanol aqueous solution have a better preservation effect.

[0118] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. Application of octacosanol in fruit preservation.

2. The use according to claim 1, characterized in that: The fruit is an apple fruit.

3. The use according to claim 1, characterized in that: The octacosanol achieves fruit preservation through at least one of the following pathways (1)-(4): (1) Inhibit the reduction of fruit firmness during storage; (2) inhibit the decrease of cellulose content in fruits during storage; (3) Inhibit the conversion of protopectin to soluble pectin during fruit storage; (4) Improve the antioxidant capacity of fruits during storage.

4. The use according to claim 3, characterized in that: The method of improving the antioxidant capacity of fruits during storage specifically includes improving the superoxide dismutase activity and catalase activity during fruit storage.

5. A method for preserving apple fruit, characterized in that: The following steps are involved: The apple fruits were soaked in an octacosanol aqueous solution, dried and stored at 15-25°C away from light.

6. The method according to claim 5, characterized in that The concentration of the octacosanol aqueous solution is 0.5-5 mg·L -1 , soaking time 6-18h.

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