Application of ethylene inhibitor in post-harvest fresh-keeping treatment and storage period prolonging of fresh cistanche deserticola

Abstract

The invention provides application of an ethylene inhibitor in post-harvest preservation treatment and storage period prolonging of fresh cistanche deserticola. 1-MCP is selected as the ethylene inhibitor. Compared with the prior art, the method has the following advantages: the first research shows that the weight loss ratio and browning degree of fresh cistanche in the storage process of 4 DEG C can be effectively reduced by treating the fresh cistanche with a proper dosage of 1-MCP, and relatively high hardness is maintained, so that relatively good overall appearance is maintained. Meanwhile, the overall quality including sensory quality, physiological quality, effective components, antioxidant activity and flavor of the cistanche deserticola in the low-temperature storage process after the cistanche deserticola is picked is maintained or improved to different extents, and the method is good in preservation effect, low in cost and easy and convenient to operate, provides powerful technical support for universal use of the cistanche deserticola, and has wide application prospects. And more possibilities are provided for modern processing of the cistanche medicinal material and product development based on fresh medicinal materials.

Description

Technical Field

[0001] The present application relates to the field of fresh-keeping technology, and in particular to the application of an ethylene inhibitor in the preparation of a product for post-harvest fresh Cistanche deserticola preservation and extended storage period. Background Art

[0002] Cistanche deserticola YC Ma is a parasitic herbaceous plant of the Orobanchaceae family. Its fleshy stems are rich in active ingredients such as phenylethanol glycosides, sugars, amino acids and trace elements. Cistanche deserticola has the traditional effects of tonifying kidney yang, benefiting essence and blood, and moistening the intestines and relieving constipation, and is known as the "desert ginseng". Modern pharmacological studies have shown that Cistanche deserticola has a wide range of antioxidant-related biological activities, such as neuroprotection, enhancing reproductive capacity, anti-fatigue and enhancing immunity. In addition, Cistanche deserticola has a history of more than 2,000 years in the main production areas of Inner Mongolia, Xinjiang and Gansu in China. It is mostly used for making soup, tea and wine, etc., and it is also common to eat fresh Cistanche directly. With Cistanche deserticola officially included in the catalog of medicinal and edible substances by the National Health Commission, its industrial production and market demand have increased significantly.

[0003] The origin of Cistanche deserticola is remote. Due to the limitations of transportation conditions and processing technology, dried herbs are currently the main sales form. However, dried Cistanche deserticola generally has the following problems:

[0004] (1) The content of polysaccharides, oligosaccharides and other effective ingredients and nutrients in fresh Cistanche deserticola is greatly reduced during the drying or baking process;

[0005] (2) The water content of Cistanche deserticola is as high as about 75%. Samples that are not completely dried are prone to mold during the relatively long drying process or transportation, resulting in economic losses after harvest.

[0006] (3) Dried Cistanche deserticola has a darker color, harder texture, and a bitter taste, which has a low consumer acceptance rate and has greatly limited the diversified development of related products.

[0007] Fresh Cistanche deserticola is rich in juice, crisp and tender, delicious, and more convenient to eat and process, but it is easy to brown and mold after harvest. The browning of products after harvest seriously reduces the sensory acceptance of consumers, and enzymatic browning is the main reason for the darkening of the color of fresh products after harvest. Enzymatic browning is the process in which phenols are oxidized to brown pigments by polyphenol oxidase (PPO) and peroxidase (POD), but PPO and its substrate polyphenols exist in plastids and vacuoles respectively in cells. Physiological disorders or mechanical damage destroy the regional distribution between enzymes and substrates to enable the reaction to occur. During the stress process of postharvest storage, the accumulation of excessive reactive oxygen species (ROS) in plants triggers the physiological and programmed regulation of cell death, thereby accelerating the oxidative aging of plant organs and microbial infection. Superoxide dismutase (SOD) and catalase (CAT) are two major antioxidant enzymes that remove excessive ROS and play an important role in maintaining a low concentration of ROS in plant cells. Under normal temperature conditions, fresh Cistanche deserticola will go moldy at the top of the stem and the root 5-6 days after harvest. Chinese patents CN113491285A, CN111213809A and CN115381015B have proven the effectiveness of low-temperature storage for extending the storage period of fresh Cistanche deserticola. However, the prior art has only conducted preliminary explorations on the preservation treatment and storage conditions of fresh Cistanche deserticola after harvest, and there are common problems such as cumbersome operation, high cost, unsuitability for industrial production and lack of quality control during storage.

[0008] 1-Methylcyclopropene (1-MCP) is an ethylene inhibitor that has been widely used and mature in the field of fruit and vegetable preservation in recent years. 1-MCP has a very low boiling point of about 10°C and has outstanding advantages such as no physiological toxicity, low concentration, low residual odor, good stability and simple operation. 1-MCP has been granted patents in China CN114176121A, CN109793043B and CN112889911A for the postharvest preservation of perishable fruits such as bananas, loquats and grapes, showing obvious application characteristics such as extended shelf life, low preservation cost, no equipment requirements and safety and pollution-free. This means that 1-MCP treatment may also have great application potential in the postharvest preservation of fresh Cistanche deserticola, which is large in size, high in water content, easy to brown and moldy, but no relevant research reports have been seen so far. Summary of the invention

[0009] In view of the above-mentioned technical limitations, the present application proposes the use of ethylene inhibitors in the post-harvest preservation and storage extension of fresh Cistanche deserticola; it can effectively maintain the freshness, medicinal and edible value of Cistanche deserticola during the post-harvest storage process, overcoming the deficiencies and defects mentioned in the background technology.

[0010] To achieve the above objectives, this application adopts the following technical solutions:

[0011] The invention of the present application is to provide an application of an ethylene inhibitor in the preparation of a product for post-harvest preservation and storage extension of fresh Cistanche deserticola.

[0012] Optionally, in the above application, the ethylene inhibitor is 1-methylcyclopropene (1-MCP).

[0013] 1-MCP treatment may delay the enzymatic browning and oxidative aging process of Cistanche deserticola by inhibiting ROS accumulation and POD activity.

[0014] Optionally, the above application is to fumigate fresh Cistanche deserticola with ethylene inhibitor after harvesting, and then pack it at 4°C and store it at a relative humidity of 65%-75%.

[0015] Optionally, in the above application, the fumigation concentration of the ethylene inhibitor is 5-10 g / cm 3 The fumigation time is 18-24h; the fumigation concentration is preferably 5 g / cm 3 The fumigation time is preferably 24h.

[0016] The dosage of 1-MCP is 0.3g-0.6g per 8kg of Cistanche deserticola. According to the volume of the enclosed space and the dosage of the 1-MCP microcapsule powder used, the concentration of the 1-MCP fumigation is converted to 5-10 g / cm 3 .

[0017] Optionally, in the above application, the fresh Cistanche deserticola is harvested in spring, and the retained part is the fleshy stem without obvious mechanical damage and pests and diseases.

[0018] The second invention of the present application is to provide a method for preserving and storing fresh Cistanche deserticola after harvest, comprising the following steps:

[0019] S1. The fresh fleshy stems of Cistanche deserticola were excavated and pre-cooled and sterilized;

[0020] S2. After pre-cooling and sterilization pre-treatment, the fleshy stems of fresh Cistanche deserticola were fumigated in an atmosphere of ethylene inhibitor;

[0021] S3. After fumigation, package and seal the Cistanche deserticola for storage.

[0022] Optionally, in the above-mentioned post-harvest preservation and storage method of fresh Cistanche deserticola, in the step S1, fresh Cistanche deserticola is dug in early April of the same year, and fleshy stems without obvious mechanical damage and pests and diseases and with uniform size, color, hardness and shape are selected for subsequent processing; the weight of a single fresh Cistanche deserticola fleshy stem ranges from 344 to 632 g.

[0023] Optionally, in the above-mentioned post-harvest preservation and storage method of fresh Cistanche deserticola, in step S1, the precooling temperature is 3-5°C, the relative humidity is 65%-75%, and the precooling time is 20h-24h; the sterilization pretreatment is to soak the fleshy stems in 75% alcohol solution for 3 min and then dry them naturally.

[0024] Optionally, in the above-mentioned method for preserving and storing fresh Cistanche deserticola after harvest, in step S2, the ethylene inhibitor is 1-methylcyclopropene, and the fumigation concentration is 5 g / cm 3 -10g / cm 3 , the fumigation time is 18h-24h.

[0025] Optionally, in the above-mentioned post-harvest preservation and storage method for fresh Cistanche deserticola, in step S3, PE cling film is used for packaging, and the thickness of the PE cling film is 0.01 mm and the size is 25 cm×50 m.

[0026] Compared with the prior art, this application has the following advantages:

[0027] The present invention is the first to show that an appropriate dose of 1-MCP treatment can effectively reduce the weight loss rate and browning degree of fresh Cistanche deserticola during storage at 4°C, maintain a high hardness, and thus maintain a good overall appearance. At the same time, the overall quality of Cistanche deserticola during post-harvest low-temperature storage, including sensory quality, physiological quality, effective ingredients, antioxidant activity and flavor, are maintained or improved to varying degrees, and the method has good preservation effect, low cost and simple operation, providing strong technical support for its universal use, and providing more possibilities for the modern processing of Cistanche deserticola medicinal materials and product development based on fresh medicinal materials.

[0028] After 100 days of storage, the contents of echinacoside, verbascoside, polysaccharides and oligosaccharides were effectively maintained, and the total flavonoids content, FRAP and DPPH free radical scavenging ability were significantly increased. The present invention also used headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS) technology to analyze and find that 1-MCP treatment may induce Cistanche deserticola to produce more abundant alcohol and aldehyde compounds with floral and fruity aroma at the end of storage. It is fully proved that 1-MCP fumigation can improve the overall quality and flavor of Cistanche deserticola during post-harvest low-temperature storage, and can be widely used in post-harvest transportation and storage of fresh Cistanche deserticola. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Shown are the effects of different treatments on the browning degree of Cistanche deserticola ( Figure 1 A) Hardness ( Figure 1 B) and weight loss rate ( Figure 1 C) effect; CK represents the control group, 5-15g / m 3Indicates different concentrations of 1-MCP treatment groups. The results are expressed as mean ± standard deviation (n=3), and different letters at each time point indicate significant differences among different treatments (P<0.05).

[0030] Figure 2 Shown are the effects of different treatments on the Cistanche deserticola glycosides ( Figure 2 A) Oligosaccharides ( Figure 2 B) and polysaccharides ( Figure 2 C) content; CK represents the control group, 5-15 g / m 3 Indicates different concentrations of 1-MCP treatment groups. The results are expressed as mean ± standard deviation (n=3), and different letters at each time point indicate significant differences among different treatments (P<0.05).

[0031] Figure 3 Shown are the effects of different treatments on the total flavonoids content of Cistanche deserticola ( Figure 3 A) DPPH free radical scavenging ability ( Figure 3 B) ABTS free radical scavenging ability ( Figure 3 C) and FRAP concentration ( Figure 3 D) effects; CK represents the control group, 5-15 g / m 3 Indicates different concentrations of 1-MCP treatment groups. The results are expressed as mean ± standard deviation (n=3), and different letters at each time point indicate significant differences among different treatments (P<0.05).

[0032] Figure 4 Shown are the effects of different treatments on superoxide ion O 2- Generation rate ( Figure 4 A) H2O2 content ( Figure 4 B) SOD activity ( Figure 4 C) CAT activity ( Figure 4 D) PPO activity ( Figure 4 E) POD activity ( Figure 4 F) and soluble quinone content ( Figure 4 G) effects; CK represents the control group, 5-15 g / m 3 Indicates different concentrations of 1-MCP treatment groups. The results are expressed as mean ± standard deviation (n=3), and different letters at each time point indicate significant differences among different treatments (P<0.05).

[0033] Figure 5The diagram shows the regulatory mechanism of 1-MCP on enzymatic browning of Cistanche deserticola during postharvest low-temperature storage; the four grids represent 0d, 20d, 60d, and 100d, respectively. The red color in the grid indicates that 1-MCP treatment has a significant increase in the content or enzyme activity, the green color indicates that 1-MCP treatment has a significant decrease in the content or enzyme activity (P<0.05), and the white color indicates that 5 g / m 3 There was no significant difference between the 1-MCP treatment and the CK group.

[0034] Figure 6 Cluster heat map showing the effects of different treatments on the low-temperature storage quality of Cistanche deserticola; CK represents the control group, 5-15 g / m 3 Represents the groups treated with different concentrations of 1-MCP.

[0035] Figure 7 Shown is a 2D-topographic map of volatile organic compounds in Cistanche deserticola ( Figure 7 A) and difference topography ( Figure 7 B); of which 5 g / m 3 After 1-MCP treatment, the samples stored at low temperature for 60 days and 100 days were named M-60 and M-100, respectively, and the samples of the control group stored at low temperature for 60 days and 100 days were named CK-60 and CK-100, respectively.

[0036] Figure 8 The fingerprint of volatile organic compounds in Cistanche deserticola is shown as follows; 3 After 1-MCP treatment, the samples stored at low temperature for 60 days and 100 days were named M-60 and M-100, respectively, and the samples of the control group stored at low temperature for 60 days and 100 days were named CK-60 and CK-100, respectively; D, dimer; M, monomer.

[0037] Fig. 9 Shown is the PCA diagram of volatile organic compounds in different Cistanche deserticola samples ( Fig. 9 A) and the Euclidean distance graph ( Fig. 9 B); of which 5 g / m 3 After 1-MCP treatment, the samples stored at low temperature for 60 days and 100 days were named M-60 and M-100, respectively, and the samples of the control group stored at low temperature for 60 days and 100 days were named CK-60 and CK-100, respectively. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solution and advantages of the present application more clear, the present application is further described in detail below. However, it should be understood that the description here is only used to explain the present application and is not used to limit the scope of the present application.

[0039] Unless otherwise defined, all technical terms and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present application, and the terms used herein in the specification of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application. The reagents and instruments used herein are all commercially available, and the characterization means involved can refer to the relevant descriptions in the prior art, which will not be repeated herein.

[0040] In order to further understand the present application, the present application is further described in detail below in conjunction with the best embodiment.

[0041] Examples 1-4

[0042] 1-MCP microcapsule powder was purchased from Xianyang Xiqin Biotechnology Co., Ltd., China, with an active ingredient content of 3.3%, 0.3 g / bag.

[0043] The post-harvest preservation method of fresh Cistanche deserticola treated with 1-MCP includes the following preservation treatment steps, and the determination methods of relevant indicators are consistent, as follows:

[0044] 1. Fresh-keeping treatment:

[0045] (1) Preprocessing:

[0046] Fresh stems of Cistanche deserticola YCMa were collected from Suhaitugacha, Bayannuorigong Sumu, Zuoqi, Alxa League, Inner Mongolia Autonomous Region (104°48′N, 40°10′E) in early April 2022 and immediately transported to the laboratory. Stems with no obvious mechanical damage and pests and uniform size, color, hardness and shape (single branch weight of 488±144 g) were selected for this study. Fresh Cistanche deserticola was gently brushed with a brush to remove the sand remaining between the scales and leaves, and precooled at 4℃ and relative humidity of 70±5% for 24 h before use. Fresh samples were soaked in 75% alcohol solution for 3 min and then dried naturally.

[0047] (2) Experimental groups:

[0048] All Cistanche deserticola were randomly divided into four groups, namely Examples 1-4, with about 8 kg (18 branches) in each group. Each group of samples was placed in a foam box and exposed to 0 (Example 1: CK), 0.3 g (Example 2: corresponding to 5 g / m 3 ), 0.6 g (Example 3: corresponding to 10 g / m 3 ) and 0.9 g (Example 4: corresponding to 15 g / m 3) in an airtight 1-MCP microcapsule powder atmosphere for 24 h. The 1-MCP microcapsule powder atmosphere is to dissolve the 1-MCP microcapsule powder in 20 mL of warm water (about 50°C) and place it in a foam box. After fumigation for 24 h, open the foam box, take out each stem, wrap it tightly with plastic wrap, and store it at 4°C and a relative humidity of 70±5% for 100 days.

[0049] Every 20 days, 3 stems were randomly taken from each group as 3 replicates, and the weight loss rate and hardness were measured. The samples were then cut into small pieces and mixed evenly. A portion was quickly frozen with liquid nitrogen and stored at -80°C for physiological index determination. A portion was vacuum freeze-dried, powdered, and stored at -20°C for component content and in vitro antioxidant activity determination.

[0050] 2. Index determination method:

[0051] (1) Weight loss rate and hardness:

[0052] The weight loss rate was determined by weighing method. The ratio of the weight difference of each stem before and after storage to the weight before storage was the weight loss rate of Cistanche deserticola, expressed as a percentage.

[0053] The hardness was measured using a pointer-type fruit hardness tester. About 1 mm of scales were removed from the middle of the upper, middle, and lower sections, and three points were measured at the same distance on the side perimeter. The average value was taken as the hardness of Cistanche deserticola (kg / cm 2 ).

[0054] (2) O 2- Production rate and H2O2 content:

[0055] The amount of superoxide anion produced per gram of fresh weight (FW) sample per minute was taken as O 2- Production rate, expressed as nmol / (min·g FW).

[0056] The amount of H2O2 contained in each gram of fresh weight tissue was taken as the H2O2 content, expressed as μmol / g FW.

[0057] (3) Enzyme activity determination:

[0058] SOD activity, CAT activity, PPO activity and POD activity were determined according to the instructions of the corresponding kits.

[0059] (4) Browning degree and soluble quinones:

[0060] The browning degree was determined by the extinction value method. 1.5 g of fresh sample was ground and homogenized with 17.0 mL of distilled water at 4°C for 20 min, centrifuged at 4000 rpm for 8 min, and the supernatant was incubated in a 25°C water bath for 5 min. The absorbance was measured at a wavelength of 410 nm, and the browning degree was expressed as A410 nm×10.

[0061] Take 1.0 g of fresh sample and homogenize it in 9.0 mL of methanol for 20 min. Centrifuge at 4000 rpm for 5 min, collect the supernatant, and measure the absorbance at 437 nm. The soluble quinone content is A437 nm / g FW.

[0062] (5) Polysaccharides and oligosaccharides:

[0063] Take 0.5 g of powder sample and extract it with 25.0 mL of 80% ethanol solution by ultrasonic (150 w, 40 kHz, 80 ° C) for 30 min. Extract twice, combine the filtrate and dilute to 50.0 mL, and precipitate for use. Take 1.0 mL of filtrate to 10.0 mL test tube in water bath to evaporate alcohol, redissolve with 5.0 mL of water, and dilute to 10.0 mL as oligosaccharide stock solution. The above precipitate evaporates until there is no alcohol smell, and extracts with 25.0 mL of water by ultrasonic (150 w, 40 kHz, 80 ° C) for 30 min. Extract twice, combine the filtrate and dilute to 50.0 mL as polysaccharide stock solution. After reaction using phenol-sulfuric acid method, the absorbance is measured at a wavelength of 490 nm, and the result is expressed as glucose content per kilogram of dry weight (g / kg).

[0064] Accurately weigh 10.00 mg of glucose standard, place it in a 100 mL volumetric flask, and add distilled water to the mark. Prepare a glucose reference stock solution with a concentration of 0.10 mg / mL and store at 4°C for later use. Accurately pipette 0.00 (blank control), 0.20, 0.40, 0.60, 0.80, 1.00, 1.20, 1.60, and 2.00 mL of glucose reference stock solution into a 10 ml stoppered test tube, fill to 2.00 mL with distilled water and react. With glucose concentration as the horizontal axis (X) and A490 nm value as the vertical axis (Y), the standard curve Y=0.0115X+0.0008 (R 2 =0.9994), with a linear range of 0.000-0.001 g / L.

[0065] (6) Glycoside ingredients:

[0066] 1) Sample extraction:

[0067] 1.0 g of powder was sonicated with 50.0 mL of 50% methanol (600 w, 40 kHz, 40 °C) for 40 min, centrifuged (4000 rpm, 5 min), and the supernatant was collected and stored at 4 °C for later use.

[0068] 2) Chromatographic conditions:

[0069] Agilent ZORBAX C18 column (250 mm×4.6 mm, 5 μm), DAD detector, 237 nm, column temperature 30°C, flow rate 1 mL / min, injection volume 10 μL. Mobile phase: acetonitrile (A)-0.5% acetic acid (B), gradient elution conditions: 10-17% A (0-5 min), 17-20% A (5-18 min), 20-23% A (18-35 min), 23-10% A (35-35.01 min), 10% A (35.01-40 min).

[0070] 3) Preparation of standard solution:

[0071] A mixed standard solution containing geniposide (0.350 mg / mL), cistancheside A (0.315 mg / mL), tubuloside A (0.352 mg / mL), echinacoside (0.785 mg / mL), isoverbascoside (0.283 mg / mL), verbascoside (0.340 mg / mL), and 2'-acetylverbascoside (0.343 mg / mL) was prepared with 50% methanol and filtered through a 0.22 μm microporous membrane for chromatographic analysis.

[0072] 4) Sample determination:

[0073] 5) Take the supernatant obtained after sample extraction in step 1), filter it through a 0.22 μm microporous filter membrane, and use it for chromatographic analysis.

[0074] (7) In vitro antioxidant activity:

[0075] 1) Total flavonoids content:

[0076] The sample solution obtained by extracting the glycoside component sample in step (6) was accurately measured and measured. The result was expressed as the rutin content per kilogram of dry weight (g / kg). With the rutin concentration as the horizontal axis (X) and the A505 nm value as the vertical axis (Y), the standard curve was obtained as Y=11.629X-0.0044 (R 2 =0.9995), with a linear range of 0.000-0.072 g / L.

[0077] 2) DPPH free radical scavenging ability:

[0078] The sample solution obtained by extracting the glycoside component sample in step (6) is transferred for determination, and the result is expressed in %.

[0079] 3) ABTS free radical scavenging ability:

[0080] The sample solution obtained by extracting the glycoside component sample in step (6) was taken, and 50% methanol was used as a control to calculate the ABTS free radical scavenging capacity.

[0081] 4) Iron reduction antioxidant capacity determination:

[0082] Take 0.1 mL of the sample solution obtained by extracting the glycoside component sample in step (6), add 3.0 mL of FRAP reagent, react at 37°C in the dark for 30 min, measure the absorbance at a wavelength of 596 nm, and the result is expressed as FeSO4 concentration. With FeSO4 concentration as the horizontal axis (X) and A596 nm value as the vertical axis (Y), the standard curve Y=0.6707X-0.0246 (R 2 =0.9981), linear range: 0.000-1.924 mmol / L.

[0083] (8) HS-GC-IMS analysis:

[0084] GC-IMS and headspace sampling equipment were used for analysis. 1.0 g of fresh Cistanche deserticola sample was weighed and placed in a 20 mL headspace bottle. It was then incubated at 60°C for 20 min. The centrifugal speed was 500 rpm and the injection needle temperature was 85°C. Finally, 500 μL of sample was injected. The chromatographic column MXT-5 (30 m×0.53 mm) was used for separation at 60°C, and N2 (purity ≥99.999%) was used as the carrier gas with a flow rate of: 0-2 min, 2 mL / min; 2-10 min, 2-10 mL / min; 10-20 min, 10-100 mL / min, and the analysis was stopped after 20 min. The drift tube was maintained at 45°C under N2 as a drift gas of 150 mL / min. The temperature of the IMS was set to 45°C. Under the same chromatographic conditions, C4-C 9n Ketone (Sinopharm Chemical Reagent Beijing Co., Ltd.) was used as an external reference to calculate the retention index (RI) of the identified volatiles. Volatile compounds were qualitatively identified by comparing the RI and drift time (DT) of standard compounds in the NIST library and GC-IMS database. The average value of the peak volume was used to calculate the relative amount of the determined volatiles.

[0085] (9) Data processing:

[0086] All samples were analyzed in triplicate, and the results are expressed as mean ± standard deviation. ANOVA was performed using IBM SPSS19 (SPSS Inc., Chicago, IL, USA), and the differences between means were evaluated using Duncan's test, with significant differences at P < 0.05. PCA and OPLS-DA analyses were performed using SIMCA 14.1 (Sartorius, USA). Cluster heatmaps and Pearson correlation analyses were performed using Origin 2021 (OriginLab Corporation, Northampton, MA, USA).

[0087] 3. Index measurement results:

[0088] (1) Figure 1 The effect of different treatments on the browning degree (A), hardness (B) and weight loss rate (C) of Cistanche deserticola. Figure 1 A, 5 g / m 3 and 10 g / m 3 Treatment can delay the increase of browning degree, which is consistent with the overall appearance change trend of Cistanche deserticola. Figure 1 As shown in B, the hardness of the control group reached the lowest value (8.48 kg / cm 2 ), compared with 15 g / m 3 The hardness of the sample group (5.39 kg / cm 2 ) decreased by 36.44%. 3 and 10 g / m 3 The hardness of the group was higher than that of the control group, but the difference was not significant (P>0.05). This result may be related to the protective effect of the scales attached to the stem surface of Cistanche deserticola. Figure 1 As shown in C, the weight loss rate of the CK group samples reached a peak on the 100th day (9.69%), compared with the control group, 15 g / m 3 The weight loss rate of the samples in the group (7.00%) was reduced by 27.70%, while at the same storage time, the 5 g / m 3 Group (2.10%) and 10 g / m 3 The weight loss rate of the samples in the two groups (1.82%) was reduced by 78.36% and 81.18%, respectively. This indicates that the treatment with an appropriate dose of 1-MCP has a certain positive effect on maintaining the appearance color, hardness and weight loss rate of FCD during post-harvest low-temperature storage, and may have great application potential in improving its post-harvest storage quality.

[0089] (2) Figure 2The results show that the total amount of 7 glycosides in Cistanche deserticola increased first and then decreased during low-temperature storage ( Figure 2 A). At the end of storage, 10 g / m 3 The total amount of 7 glycosides in the group was significantly higher than that in the other treatment groups (P<0.05). The glycosides with higher contents in Cistanche deserticola samples were mainly echinacoside, verbascoside, cistancheside A and 2'-acetylverbascoside. 3 The sum of the echinacoside and verbascoside contents in the group was nearly twice as high as the content required in the 2020 edition of the Chinese Pharmacopoeia (0.3%), indicating that this dose of 1-MCP treatment has a certain application potential for improving the medicinal value of Cistanche deserticola. Figure 2 B and C. The results showed that the content of polysaccharides and oligosaccharides increased first and then decreased during the 100-day storage process, and both reached a peak value on the 20th day of storage (157.07 g / kg and 586.27 g / kg). However, at the end of storage, the content of polysaccharides and oligosaccharides in the samples of 1-MCP treatment groups was not significantly different from that of fresh samples (78.40 g / kg and 368.86 g / kg) (P>0.05). Among them, the content of oligosaccharides in the samples of 1-MCP treatment groups was significantly higher than that of the control group on the 100th day of storage (P<0.05). In general, the samples of 1-MCP treatment groups after 100 days of storage effectively maintained the sugar content similar to that of fresh samples.

[0090] (3) Figure 3 Effects of different treatments on the total flavonoids content (A), DPPH free radical scavenging ability (B), ABTS free radical scavenging ability (C) and FRAP (D) of Cistanche deserticola. Figure 4 As shown in A, during the entire storage period, except for 15 g / m 3 The total flavonoid contents in the other treatment groups showed an increasing trend, especially in the 10 g / m 3 On the 100th day of storage, 10 g / m 3 The total flavonoids content in the group was the highest at 40.46 g / kg, which was significantly higher than that in the other treatment groups (P < 0.05). This study further explored the effect of 1-MCP treatment on antioxidant capacity by measuring the DPPH and ABTS free radical scavenging ability and FRAP ( Figure 3 B, C and D). The results show that during the entire storage period, except for 15 g / m 3 The DPPH, ABTS and FRAP values ​​of the other treatment groups showed an increasing trend, among which 10 g / m 3The fluctuation trend of DPPH, ABTS and FRAP values ​​in different treatment groups during storage was similar to the change of total flavonoids content. This indicates that total flavonoids may be one of the most important material bases for the in vitro antioxidant activity of Cistanche deserticola. In addition, except for 15 g / m 3 Except for the group, DPPH, ABTS and FRAP values ​​all reached the highest values ​​at the end of storage. 3 The highest values ​​of DPPH, ABTS and FRAP in the group were 82.70%, 91.11% and 1.84mmol / L, respectively. This indicates that the appropriate dose of 1-MCP treatment can effectively maintain the antioxidant capacity of Cistanche deserticola during low-temperature storage for up to 100 days.

[0091] (4) Figure 4 Different treatments have an impact on the effect of Cistanche deserticola O 2- Effects of production rate (A), H2O2 content (B), SOD activity (C), CAT activity (D), PPO activity (E), POD activity (F) and soluble quinone content (G). Figure 4 As shown in A, O 2- The production rate showed an increasing trend during the entire storage period. 2- The production rate reached a peak of 3.72 nmol / (min·g FW) on the 100th day of storage. Compared with the control group, each 1-MCP treatment group had a similar trend of change, among which 15 g / m 3 The results showed that excessive 1-MCP treatment may have caused excessive accumulation of ROS, accelerated oxidative damage, and finally led to rapid aging and decay of Cistanche deserticola during storage. This is consistent with the overall appearance changes observed during the experiment. Figure 4 As shown in B, the H2O2 content in the control group gradually increased during the storage period and reached a peak value (0.71 nmol / g FW) on the 100th day. 3 and 10 g / m 3 The H2O2 content of the treatment group was not higher than that of the control group during the entire storage period. The SOD activity of Cistanche deserticola in all treatment groups fluctuated after harvest ( Figure 4 C), of which 15 g / m 3 The fluctuation trend of the group and the control group was consistent. 3 and 10 g / m 3 The change trend of SOD activity in the treatment group was opposite to that of H2O2 content, which indicated that the increase of ROS content in Cistanche deserticola cells may stimulate its enzymatic antioxidant system to resist environmental stress. At the same time, the change trend of CAT activity in each treatment group during the storage period was similar to that of H2O2 content ( Figure 4 D).

[0092] PPO and POD are the most important enzymes related to browning reaction. Their changing trends are as follows: Figure 4 As shown in E and F. The PPO enzyme activity of the control group gradually increased at the beginning of storage, reached a peak value (245.9 U / (min·g FW)) on the 60th day, and then gradually decreased. 3 The change trend of PPO enzyme activity in the 5 g / m 3 and 10 g / m 3 The PPO activity of the 5 g / m 3 The peak value (231.6 U / (min·g FW)) of the group was reached on the 20th day, and then slowly decreased. 3 The activity of POD in the control group reached a peak value (298.9 U / (min·g FW)) on the 60th day, then decreased rapidly and was significantly lower than that in the other three groups on the 100th day (P<0.05). During the storage period, the activity of POD in the control group increased first and then decreased, reaching a peak value (295.6 U / (min·g FW)) on the 60th day. The change trend of POD activity in the 1-MCP treatment groups was similar to that in the control group, but was always significantly lower than that in the control group (P<0.05). On the basis of cell damage, PPO and POD enzymes will contact phenolic substrates to generate soluble quinones, which are enzymatic browning products. 10 g / m 3 The 1-MCP treatment with different doses also showed a similar PPO change trend, reaching the highest value (0.80 mg / g FW) on the 100th day of storage. The fluctuation trend of soluble quinone content in each treatment group was relatively similar during the entire storage period, showing a slow increase trend ( Figure 4 G). 5g / m 3 and 10 g / m 3 The soluble quinone content of the samples was always lower than that of the control group during 100 days of low-temperature storage. The above results indicate that 1-MCP treatment may delay the color deepening of Cistanche deserticola during storage by reducing the activity of browning-related enzymes, especially POD activity. Based on the above results on the effects of 1-MCP on the physiological quality of Cistanche deserticola, this paper further summarizes the regulatory mechanism of 1-MCP treatment on enzymatic browning of Cistanche deserticola during low-temperature storage ( Figure 5 )

[0093] (5) Figure 6 This is a cluster heat map showing the effects of different treatments on the quality of Cistanche deserticola during low-temperature storage. In order to determine the relationship between the quality parameters of Cistanche deserticola during low-temperature storage under different treatments, the cluster heat map ( Figure 6) analyzed 23 quality parameters involving sensory quality, physiological quality, active ingredient content and antioxidant capacity. The results showed that different Cistanche deserticola samples could be clustered into two categories, with significant differences between them mainly in the content of phenylethanoid glycosides and in vitro antioxidant capacity. 3 Group storage day 20 and 5 g / m 3 The samples on the 20th and 100th days of storage were clustered into one category, which indicated that the 5 g / m 3 The sensory quality, physiological quality, active ingredient content and antioxidant capacity of Cistanche deserticola can be effectively maintained at 4°C until the 100th day of storage. 3 Storage day 20, 10 g / m 3 The samples of the CK group at the 100th day of storage and the samples of the CK group at the 60th and 100th days of storage were grouped together. The sensory quality of the samples of the CK group deteriorated seriously, while the sensory quality of the samples of the 10 g / m 3 The samples in the group A had the highest level of phenylethanoid glycosides content and in vitro antioxidant capacity among all samples. The results showed that during low-temperature storage, phenylethanoid glycosides in Cistanche deserticola gradually accumulated under the action of multiple enzymes, and excessive 1-MCP treatment may accelerate cellular oxidative damage, thereby increasing the dissolution of phenylethanoid glycosides.

[0094] (6) Figure 7 The 2D-topography (A) and difference topography (B) of volatile organic compounds in Cistanche deserticola. The sensory quality, physiological quality, effective ingredients and antioxidant capacity of Cistanche deserticola stored at low temperatures with different treatments were evaluated. It was found that 5 g / m 3 The 1-MCP treatment with a certain dose can effectively maintain the overall quality similar to that of fresh samples until 100 days of low temperature storage. Odor is also an important factor that seriously affects the commercial value of Cistanche deserticola, but the effect of 1-MCP treatment on the odor of Cistanche deserticola is still unknown. Therefore, this study further used HS-GC-IMS technology to analyze fresh samples (fresh); 5 g / m 3 Changes in VOCs in samples stored at low temperature for 60 days (M-60) and 100 days (M-100) after 1-MCP treatment; changes in VOCs in samples stored at low temperature for 60 days (CK-60) and 100 days (CK-100) in the control group. Figure 7 As can be seen in A, most of the signals occur at retention times of 100-800 s and drift times of 1.0-1.8 ms. In order to more clearly compare the effects of different treatments on volatile substances, Figure 7B Select the spectrum of the fresh sample as a reference, deduct the reference treatment of the other four samples, and obtain the sample difference comparison diagram. It can be found that within the drift time of 1.0-1.5 ms, the concentration of VOCs contained in the stored samples is significantly higher than that in the fresh samples. This indicates that during the storage process, Cistanche deserticola may produce many new volatile organic compounds as it gradually matures, thus affecting the flavor after storage.

[0095] In this study, HS-GC-IMS technology was used to analyze the volatile organic compounds of Cistanche deserticola with different treatments, and qualitative characterization information was provided. Such as the compounds in Table 1. A total of 47 peaks were detected from the Cistanche deserticola samples, and 38 volatile compounds were identified, including 19 alcohols, 9 aldehydes, 4 esters, 1 olefin, 2 oxiranes, 1 ketone and 2 ethers. Among them, 2-ethylhexanol, 2-hexanol, isopentenol, isopentanol, isobutyl alcohol, n-hexanol, phenylacetaldehyde, benzaldehyde, 3-methylthiopropanal and 2,4-dimethyl-1,3-dioxolane, a total of 10 compounds, have monomer and dimer forms. Table 1 shows the qualitative results of the effect of 1-MCP treatment on the volatile organic compounds of Cistanche deserticola.

[0096] Table 1 No. Compound CAS# RI Rt [sec] Dt [au] 1 2-Phenylethanol 60-12-8 1103.1 758.518 1.30147 2 Guaiacol 90-05-1 1082 707.902 1.11783 3 Ethyl levulinate 539-88-8 1065.5 670.932 1.19331 4 Benzeneacetaldehyde(M) 122-78-1 1046.5 630.602 1.26157 5 Benzeneacetaldehyde(D) 122-78-1 1046.9 631.41 1.54382 6 2-Ethyl-1-hexanol(D) 104-76-7 1036.5 610.385 1.80694 7 2-Ethyl-1-hexanol(M) 104-76-7 1035.9 609.306 1.42103 8 n-Octanol 111-87-5 1044.7 626.916 1.4538 9 Benzenemethanol 100-51-6 1041.5 620.414 1.5015 10 ethyl trans-2-hexenoate 27829-72-7 1041.2 619.899 1.32217 11 Limonene 138-86-3 995.1 532.779 1.6879 12 Benzaldehyde(M) 100-52-7 952.9 449.915 1.14959 13 Benzaldehyde(D) 100-52-7 953 450.084 1.46722 14 3-(Methylmercapto)propionaldehyde(M) 3268-49-3 898 360.928 1.0919 15 3-(methylsulfanyl)propanal(D) 3268-49-3 897.6 360.307 1.39519 16 2-hexanol(M) 626-93-7 783.9 235.024 1.29 17 2-hexanol(D) 626-93-7 784.6 235.659 1.56338 18 1,3-butanediol 107-88-0 782.7 233.842 1.37709 19 3-Methyl-2-buten-1-ol(M) 556-82-1 770 222.38 1.0942 20 3-Methyl-2-buten-1-ol(D) 556-82-1 769.6 222.013 1.35667 21 (Z)-2-Penten-1-ol 1576-95-0 762.7 215.983 0.94326 22 ethyl butanoate 105-54-4 761.4 214.904 1.21028 23 1-Butanol, 3-methyl-(M) 123-51-3 722.4 184.042 1.24357 24 1-Butanol, 3-methyl-(D) 123-51-3 724.5 185.567 1.49023 25 1,3-Dioxolane, 2,4-dimethyl, cis(M) 3390-12-3 700.1 168.447 1.09221 26 1,3-Dioxolane, 2,4-dimethyl, cis(D) 3390-12-3 701.1 169.125 1.33233 27 2,3-pentandione 600-14-6 698.8 167.599 1.21367 28 1,2-Dimethoxyethane 110-71-4 646.2 139.292 1.30711 29 2-methyl Butanal 96-17-3 657.4 144.716 1.39867 30 3-Methyl butanal 590-86-3 637.8 135.393 1.40147 31 1-Propanol, 2-methyl-(M) 78-83-1 619.6 127.257 1.1763 32 1-Propanol, 2-methyl-(D) 78-83-1 618.4 126.748 1.37064 33 Ethyl Acetate 141-78-6 597.6 118.067 1.33637 34 Butanal 123-72-8 563.9 105.302 1.28432 35 Ethanol 64-17-5 480.9 79.395 1.06183 36 2-Methyl-3-furanthiol 28588-74-1 859.7 312.195 1.1392 37 Hexanol(M) 111-27-3 861.3 314.073 1.33237 38 Hexanol(D) 111-27-3 860.2 312.78 1.652

[0097] In Table 1, M: monomer; D: dimer; RI: retention index; Rt: retention time; Dt: drift time.

[0098] (7) Figure 8 is the fingerprint of volatile organic compounds in Cistanche deserticola, such as Figure 8 As shown in the figure, the types and concentrations of volatile organic compounds in fresh samples are the least, and the volatile organic compounds in samples with different treatments and different storage times are quite different. The compounds in the yellow box have higher concentrations in fresh samples. They are mainly some alcohols, aldehydes and esters with fruity and floral odors, including 2-hexanol, isopentanol, isobutanol, n-butyraldehyde, 2-methylbutyraldehyde, 3-methylbutyraldehyde, ethyl acetate and ethyl levulinate. The compounds in the red box have a concentration of 5 g / m 3 The samples stored on the 60th day after the dosage treatment were more abundant, including 1,3-butanediol, trans-2-ethylhexanoate, 2,3-pentanedione and ethylene glycol dimethyl ether. 3The concentrations of the compounds in the orange frame were higher in the samples of the control group on the 100th day of storage and the samples of the control group on the 60th day of storage. They were mainly alcohols with richer floral and fruity aromas, such as 2-phenylethanol, 2-ethylhexanol, isopentenol, cis-2-pentenol, n-hexanol and 2-methyl-3-furanthiol, etc. The compounds in the orange frame were the most abundant in the samples of the control group, especially in the samples at the end of storage. They were mostly excessive aldehydes with bad odors, such as phenylacetaldehyde, benzaldehyde and 3-methylthiopropionaldehyde.

[0099] (8) Fig. 9 The PCA diagram (A) and Euclidean distance diagram (B) of volatile organic compounds in different Cistanche samples are shown in the figure. As shown in the figure, through the principal component analysis of volatile compounds in Cistanche, it was found that PC1 was 46%, PC2 was 27%, and the cumulative total contribution rate was 73%, which can be used as a high-quality model to distinguish the effects of different treatment methods on volatile substances in Cistanche. Samples of Cistanche treated with different treatments at different storage times were well distinguished. 5 g / m 3 The PC2 scores of the samples stored on days 60 and 100 were quite different, and they were far away from the fresh samples. 3 The group produces richer fruit, vegetable and plant aromas during storage. These flavor substances may be 5 g / m 3 The reason why the smell of the group samples is quite different from that of the fresh samples. Fig. 9 B is the fingerprint based on Euclidean distance. The results show that the similarity of each group of samples is high and different groups of samples can be well distinguished. Consistent with the results of principal component analysis, the fresh samples are close to the control group samples, and the 5 g / m 3 The distance between the two groups of samples was far. This once again confirmed that the effect of 1-MCP treatment on the VOCs of Cistanche deserticola was far greater than the storage time. This result indicated that 1-MCP treatment may cause Cistanche deserticola to produce more alcohols and esters with floral and fruity aromas during storage, resulting in a more differentiated mature flavor.

[0100] In summary, 5 g / m 3 The 1-MCP treatment can increase the content of phenylethanoid glycosides and inhibit the accumulation of ROS and the generation of soluble quinones. At 4°C, this treatment can effectively maintain the overall quality and flavor of fresh Cistanche deserticola for 100 days. This method has good preservation effect, low cost and simple operation, and has good application prospects for postharvest storage of Cistanche deserticola.

[0101] Embodiment 5:

[0102] The preservation treatment method for fresh Cistanche deserticola in this example is the same as the 1-MCP treatment group in Example 2, except that the treated whole Cistanche deserticola is cut into thin slices with a thickness of 0.3-0.5 cm using a ceramic knife, placed in a PE transparent smooth vacuum bag, evacuated, and stored at 4°C.

[0103] The experimental results show that the low-temperature storage period of fresh slices under this treatment can be effectively extended to 20 days. The weight loss rate after 20 days of storage was 1.61±0.28%, and there was no odor or mildew, and it still maintained a good hardness and appearance color. In recent years, fresh-cut products have been in great demand worldwide because they can be eaten immediately, which is convenient and retains the fresh characteristics of raw products, which is very consistent with the natural, nutritious, and fast-paced lifestyle that people pursue. The above experimental results confirm the application of 1-MCP treatment combined with low-temperature storage technology in the preservation of Cistanche products.

[0104] Comparative Example 1:

[0105] The preservation treatment method for fresh Cistanche deserticola in this comparative example is the same as the 1-MCP treatment group in Example 2, except that the concentration of 5 g / m 3 1-MCP was sealed and fumigated for 18 h.

[0106] The experimental results showed that after 18 hours of fumigation, the sensory indicators of Cistanche deserticola such as weight loss rate, hardness and browning degree in the 1-MCP treatment group were effectively improved during low-temperature storage, but the above preservation effects were not as good as those of 1-MCP treatment for 24 hours. In addition, the 1-MCP implementation method selected in this experiment was to dissolve the microcapsule powder in warm water for fumigation. When the fumigation time was short, the residual odor on Cistanche deserticola was also slightly stronger.

[0107] Comparative Example 2:

[0108] The preservation treatment method for fresh Cistanche deserticola in this comparative example is the same as the 1-MCP treatment group in Example 2, except that the concentration of 5 g / m 3 1-MCP was sealed and fumigated for 30 h.

[0109] The experimental results showed that after 30 hours of fumigation, the sensory indicators of Cistanche deserticola such as weight loss rate, hardness and browning degree in the 1-MCP treatment group were effectively improved during low-temperature storage, but there was no statistical difference between the above preservation effects and the 24-hour 1-MCP treatment. When the airtight smoking time was greater than 24 hours, the residual odor on Cistanche deserticola almost disappeared.

[0110] Comparative Example 3:

[0111] The preservation treatment method for fresh Cistanche deserticola in this comparative example is the same as that of the CK group in Example 1, except that no sterilization treatment by immersion in 75% alcohol solution is performed, and PE preservative film is directly used for packaging and stored at 4°C and a relative humidity of 70±5%.

[0112] The experimental results showed that the roots of the Cistanche deserticola treated in the comparative example began to mold on the 20th day of storage, and mold and rot occurred at the wound on the 40th day. However, the roots of the CK group in Example 1 began to mold on the 60th day.

[0113] Comparative Example 4:

[0114] The preservation treatment method for fresh Cistanche deserticola in this comparative example is the same as that of the CK group in Example 1, except that no sterilization treatment by immersion in 75% alcohol solution is performed, and no PE preservative film is used for packaging. The fresh Cistanche deserticola is directly stored at 4°C and a relative humidity of 70±5%.

[0115] The experimental results show that the roots of the Cistanche deserticola treated in the comparative example began to mold on the 20th day of storage, and the surface began to wilt due to water loss. On the 40th day, mold and rot occurred at the wound. On the 60th day, in addition to mold and rot at the root, wound and stem tip, the entire fleshy stem had begun to soften.

[0116] In summary, the experiments show that the present invention uses 1-MCP to fumigate fresh Cistanche deserticola, and its specific concentration and fumigation time need to be controlled to effectively inhibit its post-harvest quality deterioration phenomena such as enzymatic browning, oxidative aging and mildew, and maintain its freshness, optimal medicinal and edible value, thereby extending the storage period, and providing more possibilities for the industrial production of Cistanche deserticola medicinal materials and the development of products based on fresh medicinal materials.

[0117] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. Application of ethylene inhibitors in postharvest preservation and storage extension of fresh Cistanche deserticola.

2. The use according to claim 1, characterized in that: The ethylene inhibitor is selected as 1-methylcyclopropene.

3. The use according to claim 2, characterized in that: The method is to fumigate fresh Cistanche deserticola with ethylene inhibitor after harvesting, and then pack the fumigated products at 4°C and store them at a relative humidity of 65%-75%.

4. The use according to claim 3, characterized in that: The fumigation concentration of the ethylene inhibitor is 5-10 g / cm 3 , the fumigation time is 18-24h.

5. The use according to claim 4, characterized in that: The fresh Cistanche deserticola is harvested in spring, and the retained parts are fleshy stems without obvious mechanical damage and pests and diseases.

6. A method for preserving and storing fresh Cistanche deserticola after harvest, characterized in that: The following steps are involved: S1. The fresh fleshy stems of Cistanche deserticola were excavated and pre-cooled and sterilized; S2. After pre-cooling and sterilization pre-treatment, the fleshy stems of fresh Cistanche deserticola were fumigated in an atmosphere of ethylene inhibitor; S3. After fumigation, pack the Cistanche deserticola and store it.

7. The method for preserving and storing fresh Cistanche deserticola after harvest according to claim 6, characterized in that: In step S1, fresh Cistanche deserticola is harvested in early April of the same year, and fleshy stems without obvious mechanical damage and pests and diseases and uniform in size, color, hardness and shape are selected for subsequent processing; the weight of a single fresh Cistanche deserticola fleshy stem ranges from 344 to 632 g.

8. The method for preserving and storing fresh Cistanche deserticola after harvest according to claim 6, characterized in that: In step S1, the precooling temperature is 3-5°C, the relative humidity is 65%-75%, and the precooling time is 20h-24h; The sterilization pretreatment was to soak the fleshy stems in 75% alcohol solution for 3 minutes and then dry them naturally.

9. The method for preserving and storing fresh Cistanche deserticola after harvest according to claim 6, characterized in that: In step S2, the ethylene inhibitor is 1-methylcyclopropene, and the fumigation concentration is 5 g / cm 3 -10g / cm 3 , the fumigation time is 18h-24h.

10. The method for preserving and storing fresh Cistanche deserticola after harvest according to claim 6, characterized in that: In step S3, PE cling film is used for packaging, and the thickness of the PE cling film is 0.01 mm and the size is 25 cm×50 m.

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