CN104304425A - Fresh-cut aralia elata seem coating material and coating preservation method - Google Patents

Abstract

The invention provides a coating material for fresh-cut thorn buds and a coating preservation method, the steps of which are as follows: (1) selection; (2) cleaning; (3) finishing; (4) preparation of coating solution; (5) coating film; (6) drying; (7) storage. The coating liquid components include carboxymethyl chitosan, clove essential oil, glycerin, sodium carboxymethyl cellulose, ethanol, calcium lactate and water. The present invention is applied to the fresh-keeping of fresh-cut thorn buds to maintain the original unique flavor and nutritional components of the thorn buds to the greatest extent, saving the processing time for eating, and at the same time, the coating liquid has properties such as edible, bacteriostasis and anti-oxidation, etc. The coating film on the surface of fresh-cut thorn buds can reduce respiration, prevent color change, reduce water evaporation and infestation of diseases and insect pests, and effectively prolong the storage period of fresh-cut thorn buds. The fresh-cut thorn buds prepared by this technology have high quality and hygienic quality, and can reach the standard of fresh-cut products. The fresh-keeping period of the product is extended from 2 to 3 days to 7 to 8 days, and the price can be increased by 1 to 2 times.

Description

Coating material and fresh-keeping method of fresh-cut thorn buds

technical field

The invention relates to the fresh-keeping field of fresh-cut wild vegetables, in particular to a film-coating material for fresh-cut prickly shoots and a film-preservation method.

Background technique

Aralia elata Seem , scientific name Aralia elata Seem, commonly known as Aralia elata Seem, commonly known as Aralia elata Seem, belongs to small deciduous trees, grows in forest margins, shrubs, and open spaces in forests, and is mainly distributed in China Northeast region. The edible part is tender buds, which can be eaten raw, stir-fried, sauced, made into soup, stuffed, and processed into small pickles with different flavors. It has a delicate and meaty flavor, and its flavor is unique. It is currently the most popular pickle in the domestic and foreign markets. The excellent mountain wild vegetables are known as "the king of wild vegetables". Thorn shoots are rich in nutrients and mainly contain protein, fat, carbohydrates, dietary fiber, vitamins B ₁ , B ₂ , niacin, vitamin C, sodium, calcium, magnesium, iron, manganese, zinc, barium, lead, copper, phosphorus , cobalt, chromium, nickel, boron, strontium and peptides and other components.

At present, the processed products of thorn buds are mainly frozen, dried and pickled, and can be preserved for a long time. However, after these products are processed, they lose their original freshness before processing, and their nutritional components, flavor and aroma have also changed. With the accelerated pace of modern life and the improvement of the quality of life, as well as the concern for their own health, people's consumption patterns and eating patterns are gradually developing in the direction of nutrition, health care, convenience, hygiene, and nature. Fresh-cut products are exactly what the times demand. product needed.

The thorny shoots have the characteristics of crisp and tender tissue, easy to cut, and are suitable for fresh-cut processing. However, after cleaning and cutting, mechanical damage is caused, causing rapid activation of respiration and metabolic reactions, and rapid decline in quality. The shelf life of the product greatly reduces the commodity value of fresh-cut thorny shoots. Therefore, the key to solving the fresh-keeping problem of fresh-cut products is to choose natural and environmentally friendly coating materials and to develop more efficient fresh-keeping methods.

Contents of the invention

The purpose of the present invention is to meet the needs of consumers and provide a fresh-cut thorn bud coating material and a coating film preservation method with good fresh-keeping effect, so as to solve the problems existing in the fresh-cut thorn bud fresh-keeping process.

The technical solution of the present invention is: the fresh-cut prickly bud coating material is mixed with the following mass fraction raw materials to form a film-forming liquid: 0.01%-0.05% clove essential oil, 0.1%-0.5% ethanol, 0.75%-1.75% carboxymethyl Chitosan, 0.5%~1.5% calcium lactate, 0.5%~1.5% glycerin, 0.5%~1.0% sodium carboxymethyl cellulose, the balance water. The carboxymethyl chitosan in the formula is soluble in neutral, alkaline and slightly acidic water, and its properties are relatively stable. Its application range is stronger than that of chitosan, and it has strong antibacterial and antioxidative properties. The clove essential oil in the formula is a natural antibacterial agent and antioxidant, and its function can be greatly enhanced by compounding with other preservatives. Calcium lactate in the formula is a hardening agent, which can increase the brittleness of fresh-cut prickly shoots and prevent the product from softening. Glycerin in the formula is a plasticizer and humectant, which can increase the ductility of the film, prevent the coating liquid from brittle cracking after drying, and at the same time have a water-locking effect to prevent water loss. The sodium carboxymethyl cellulose in the formula is an emulsification stabilizer and thickener, which can maintain the stability of the properties of the coating material during the mixing and homogenization process. Ethanol in the formula can promote the mixing of glycerin and clove essential oil with other coating materials. Using this formula to prepare the coating material can effectively prevent the water loss of fresh-cut thorn buds, increase the antibacterial and antioxidant capacity of fresh-cut thorn buds, reduce the color change of fresh-cut thorn buds, and prolong its fresh-keeping period. All materials are natural or food grade, so the coating liquid is edible.

In the preparation of the above coating solution, first dissolve 0.05% clove essential oil in 0.3% ethanol, then mix with 0.75% carboxymethyl chitosan, 0.5% calcium lactate, 1.0% glycerin and 1.0% sodium carboxymethyl cellulose solution .

In the preparation of the above-mentioned coating solution, each component should be homogenized when mixed, the time is 6 minutes, and the homogenization speed is 4000r/min.

A method for fresh-cut fresh-cut thorn buds coated with a film, comprising the following steps:

(1) Selection: Select fresh thorn buds without mechanical damage and no pests and diseases.

(2) Cleaning: Rinse the thorn buds obtained in step (1) with clean water.

(3) Finishing: remove the thorns from the thorny shoots obtained in step (2), trim and cut them into sections.

(4) Preparation of coating solution: by mass fraction, 0.01% to 0.05% clove essential oil, 0.1% to 0.5% ethanol, 0.75% to 1.75% carboxymethyl chitosan, 0.5% to 1.5% calcium lactate, 0.5% ～1.5% glycerin, 0.5%～1.0% sodium carboxymethyl cellulose, the rest water, mix to make film-forming solution.

(5) Coating: Put the fresh-cut thorn shoots obtained in step (3) into the coating liquid obtained in step (4) for dip coating.

(6) Drying: Take out the dip-coated fresh-cut shoots obtained in step (5), drain the dipping solution, and dry in the air.

(7) Storage: The fresh-cut prickly shoots obtained in step (6) are subpackaged and stored.

The flushing in step (2) is to flush with clean water at 10°C to 15°C.

Wherein the trimming and sectioning in the step (3) is trimming the prickly buds to a length of 5 cm to 7 cm.

The temperature of the coating solution in step (5) is 10°C to 15°C, and the dipping time is 1 min to 3 min.

Wherein the storage temperature in step (7) is 1°C-5°C.

Preferable: fresh-cut fresh-cut thorn buds coated fresh-keeping method, its steps are as follows:

(1) Selection: Select fresh thorn buds without mechanical damage and no pests and diseases.

(2) Cleaning: Rinse the thorn shoots obtained in step (1) with water at 10°C to 15°C to remove surface dust. the

(3) Finishing: Remove the prickles from the prickly buds obtained in step (2) with a sterilized sharp instrument, and trim the prickly buds to a length of 5cm to 7cm.

(4) Preparation of coating solution: 0.01% to 0.05% clove essential oil, 0.1% to 0.5% ethanol, 0.75% to 1.75% carboxymethyl chitosan, 0.5% to 1.5% calcium lactate, Mix 0.5%～1.5% glycerin and 0.5%～1.0% sodium carboxymethyl cellulose to prepare film-forming solution.

(5) Coating: Put the fresh-cut thorn shoots obtained in step (3) into the coating liquid obtained in step (4) for dip coating.

(6) Drying: Take out the dip-coated fresh-cut shoots obtained in step (5), drain the dip-coating solution, and evaporate the surface water by natural drying.

(7) Storage: Pack the fresh-cut thorn shoots obtained in step (6) into plastic boxes and store them at 1°C to 5°C.

The beneficial effects of the present invention are as follows: (1) The technical solution slightly processes the prickly buds, keeps the original fresh prickly buds, nutrients, flavor and aroma to the greatest extent, and the fresh-cut prickly buds are convenient to eat and edible; The 100% eating rate can save eating time, reduce product transportation and waste disposal costs, and satisfy people's pursuit of nutrition, health care, convenience, hygiene, and natural consumption patterns and dietary concepts. (2) Coating the fresh-cut thorn buds can protect the mechanical damage caused by cleaning and cutting, prevent the growth and reproduction of pests and diseases and environmental pollution, reduce water loss, and avoid fibrosis of fresh-cut thorn buds. (3) Natural products such as carboxymethyl chitosan and clove essential oil in the coating liquid have the advantages of safety and non-toxicity, strong antibacterial and anti-oxidative properties, good water solubility and thermal stability, and wide range of action. The thorn buds are free from any pollution, which improves the edible safety of the fresh-cut thorn buds. (4) The fresh-cut thorn buds prepared by this technical scheme have high quality and hygienic quality, which can meet the standards of fresh-cut products. The fresh-keeping period of the product is extended from 2 to 3 days to 7 to 8 days, and the price can be increased by 1 to 2 times. At the same time, the technical operation is simple, the source of coating liquid raw materials is extensive, and it is easy to popularize and apply. (5) Using this formula to prepare coating materials can effectively prevent the water loss of fresh-cut thorn buds, increase the antibacterial and antioxidant capacity of fresh-cut thorn buds, reduce the color change of fresh-cut thorn buds, and prolong their fresh-keeping period.

The experimental method of the present invention will be further described in detail below in conjunction with experimental examples.

Description of drawings

Figure 1 is the change curve of the weight loss rate of fresh-cut thorn shoots in different storage periods.

Fig. 2 is the change curve of chlorophyll content of fresh-cut thorn shoots in different storage periods.

Figure 3 is the change curve of catalase activity of fresh-cut thorny shoots in different storage periods.

Figure 4 is the change curve of malondialdehyde concentration in fresh-cut thorny shoots during different storage periods.

Figure 5 is the change curve of polyphenol oxidase activity of fresh-cut thorny shoots in different storage periods.

Detailed ways

Example 1

The method for fresh-cut fresh-cut thorn buds coated with film, the steps are as follows:

(1) Selection: Select fresh thorn buds without mechanical damage and no pests and diseases.

(2) Cleaning: Rinse the thorn buds obtained in step (1) with 10°C water to remove surface dust. the

(3) Finishing: Remove the prickles from the prickly buds obtained in step (2) with a sterilized sharp instrument, and trim the prickly buds to a length of 5cm to 7cm.

(4) Preparation of coating solution: according to the mass fraction of 100%, first dissolve 0.01% clove essential oil in 0.3% ethanol, then mix with 1.75% carboxymethyl chitosan, 0.5% calcium lactate, 1.0% glycerin and 0.5% carboxymethyl The base cellulose sodium solution is mixed, each component should be homogenized when mixing, the time is 6min, and the homogenization speed is 4000r/min.

(5) Coating: put the fresh-cut thorn shoots obtained in step (3) into the coating liquid obtained in step (4) for dip coating, the temperature of the coating liquid is 10°C, and the dip coating time is 2 minutes.

(6) Drying: Take out the dip-coated fresh-cut shoots obtained in step (5), drain the dip-coating solution, and evaporate the surface water by natural drying.

(7) Storage: The fresh-cut thorn shoots obtained in step (6) were packed into plastic boxes and stored at 4°C.

Example 2:

The method for fresh-cut fresh-cut thorn buds coated with film, the steps are as follows:

(1) Selection: Select fresh thorn buds without mechanical damage and no pests and diseases.

(2) Cleaning: Rinse the thorn buds obtained in step (1) with 10°C water to remove surface dust.

(3) Finishing: Remove the prickles from the prickly buds obtained in step (2) with a sterilized sharp instrument, and trim the prickly buds to a length of 5cm to 7cm.

(4) Preparation of coating solution: according to the mass fraction of 100%, first dissolve 0.05% clove essential oil in 0.3% ethanol, then mix with 0.75% carboxymethyl chitosan, 0.5% calcium lactate, 1.0% glycerin and 1.0% carboxymethyl The base cellulose sodium solution is mixed, each component should be homogenized when mixing, the time is 6min, and the homogenization speed is 4000r/min.

(5) Coating: put the fresh-cut thorn shoots obtained in step (3) into the coating liquid obtained in step (4) for dip coating, the temperature of the coating liquid is 10°C, and the dip coating time is 2 minutes.

(6) Drying: Take out the dip-coated fresh-cut shoots obtained in step (5), drain the dip-coating solution, and evaporate the surface water by natural drying.

(7) Storage: The fresh-cut thorn shoots obtained in step (6) were packed into plastic boxes and stored at 4°C.

Example 3:

The method for fresh-cut fresh-cut thorn buds coated with film, the steps are as follows:

(1) Selection: Select fresh thorn buds without mechanical damage and no pests and diseases.

(2) Cleaning: Rinse the thorn buds obtained in step (1) with 10°C water to remove surface dust. the

(3) Finishing: Remove the prickles from the prickly buds obtained in step (2) with a sterilized sharp instrument, and trim the prickly buds to a length of 5cm to 7cm.

(4) Preparation of coating solution: according to the mass fraction of 100%, first dissolve 0.03% clove essential oil in 0.3% ethanol, then mix with 1.25% carboxymethyl chitosan, 0.5% calcium lactate, 1.0% glycerin and 0.75% carboxymethyl The base cellulose sodium solution is mixed, each component should be homogenized when mixing, the time is 6min, and the homogenization speed is 4000r/min.

(5) Coating: put the fresh-cut thorn shoots obtained in step (3) into the coating liquid obtained in step (4) for dip coating, the temperature of the coating liquid is 10°C, and the dip coating time is 2 minutes.

(6) Drying: Take out the dip-coated fresh-cut shoots obtained in step (5), drain the dip-coating solution, and evaporate the surface water by natural drying.

(7) Storage: The fresh-cut thorn shoots obtained in step (6) were packed into plastic boxes and stored at 4°C.

Experimental example

Study on the fresh-keeping effect of fresh-cut thorn buds.

Select the technical scheme of above-mentioned 3 examples, i.e. embodiment 1, embodiment 2 and embodiment 3, carry out fresh-keeping comparative experiment with the thorn buds that have not been treated with coating film (hereinafter referred to as untreated).

Technical plan for untreated fresh-cut thorn buds: select fresh thorn buds without mechanical damage and no pests and diseases; rinse with 10°C water to remove surface dust; use sterilized sharp utensils to remove skin thorns. The shoots are trimmed to a length of 5cm to 7cm.

All samples in each group were stored at 4°C, and the physical and chemical indicators were tested every 3 days. The testing items included weight loss rate, chlorophyll, catalase (CAT), malondialdehyde (MDA), and polyphenol oxidase activity (PPO). . The samples on the 6th day were selected for sensory evaluation and microbial index determination. The determination method is as follows:

(1) Sensory evaluation

Take 10 samples randomly, and invite 10 people to participate in the evaluation, and score them one by one according to freshness, color, smell, texture and appearance. The individual score ranges from 1 to 10 points, divided into three grades, and 1 to 4 points indicate quality Extremely poor, the sample is completely deteriorated and cannot be eaten; 4-7 points indicate the quality is average, although there are defects, but it does not affect consumption; 7-10 points indicate the quality is good.

(2) The microorganisms are tested according to the following national standards, and the results are expressed in CFU/g fresh weight (FW):

GB4789.2-2010 Determination of the total number of colonies in food microbiology inspection; GB4789.3-2010 Food microbiology inspection coliform count; GB4789.15-2010 Food microbiology inspection mold and yeast count.

(3) Determination of weight loss rate

(4) Determination of chlorophyll

Take 2g of fresh thorn buds, three parts in total, put them into a mortar and add 2-3mL95% ethanol to make a homogenate, then add 10mL of ethanol, continue to grind until the tissue turns white and rest for 3-5min. Centrifuge for 30 min with a centrifuge to take the supernatant for later use. Put the supernatant into a 25mL volumetric flask and shake to volume with 95% ethanol. Pour the extract into a cuvette with an optical path of 1 cm, and measure the absorbance at wavelengths of 665 nm and 649 nm with 95% ethanol as a control. The result is calculated according to the following formula:

In the formula:

A ₆₆₅ - absorbance measured at a wavelength of 665nm;

A ₆₄₉ - absorbance measured at a wavelength of 649nm;

V - the volume of the extract (mL);

n - dilution factor;

m _f - the fresh weight of the sample (g).

(5) Determination of catalase (CAT)

Take 2g of thorn buds, add a little quartz sand, then add 5mL of phosphate buffer solution (0.2mol/L, pH=7.8, containing 2%PVPP), grind in an ice bath until it is evenly slurry, transfer it to a 10mL centrifuge tube, and Centrifuge at 3000r/min at low temperature (4°C) for 10min, take the supernatant, and add 5mL of phosphate buffer solution (0.2mol/L, pH=7.8).

Take 4 50 mL Erlenmeyer flasks (3 for measurement and 1 for control), add 2 mL of enzyme solution to each bottle for measurement, then add 2.5 mL of H ₂ SO ₄ (10%) to the control bottle and shake well , to terminate the reaction; then add 2.5 mL H ₂ O ₂ (0.1mol/L) to the measuring bottle and shake well, while timing, put it in a constant temperature water bath at 30°C for 10 minutes, then immediately add 2.5 mL H ₂ SO ₄ (10%) to the measuring bottle The reaction was terminated in the bottle, and then titrated with KMnO ₄ (0.1mol/L) standard solution, with the pink color not fading for 30s as the end point.

Calculate according to the following formula:

In the formula:

V control——contrast KMnO ₄ titration milliliters;

V titration - after the enzyme reaction KMnO _Titrated milliliters;

V _T - the total volume of the extracted enzyme solution (mL);

m _f - sample fresh weight (g);

Vs - the volume of enzyme solution used in the measurement (mL);

t —response time (min).

(6) Determination of malondialdehyde (MDA)

Take 2g of thorn buds, add a little quartz sand, then add 5mL of phosphate buffer solution (0.2mol/L, pH=7.8, containing 2%PVPP), grind in an ice bath until it is evenly slurry, transfer it to a 10mL centrifuge tube, and Centrifuge at 3000r/min at low temperature (4°C) for 10min, take the supernatant, and add 5mL of phosphate buffer solution (0.2mol/L, pH=7.8).

Take 4 25mL stoppered test tubes (3 for determination and 1 for control), add 2 mL of enzyme solution to 3 stoppered test tubes, and add 2 mL of phosphate buffer solution (0.2 mol/L, pH=7.8) as a control, then add 2mL TBA (0.5%) to 3 test tubes with stoppers, mix and boil in a water bath at 100°C for 30min, then centrifuge once after cooling, take the supernatant to measure 450nm, 532nm and 600nm respectively Absorbance value at nm.

In the formula:

V _T - the total volume of the extracted enzyme solution (mL);

m _f - sample fresh weight (g);

Vs - the volume of enzyme solution used in the measurement (mL).

(7) Determination of polyphenol oxidase (PPO)

Take 2g of thorny shoots, add a little quartz sand, then add 5mL of phosphate buffer solution (0.2mol/L, pH=6.4, containing 2%PVPP), grind in an ice bath until it is evenly slurry, transfer it to a 10mL centrifuge tube, and Centrifuge at 12000r/min at low temperature (4°C) for 10min, and the supernatant is the crude extract of the enzyme.

Take 4 test tubes, add 3mL of 0.5mol/L catechol solution and 0.1mL phosphate buffer solution (0.2mol/L, pH=6.4) to one of them as a control; mL, and then add 3 mL of 0.5 mol/L catechol solution to the enzyme solution. After reacting at 25°C for 5s, pour it into a cuvette, place it in the sample chamber of the spectrophotometer, immediately start the stopwatch to record the time, measure the absorbance (OD) value at 398 nm, and read once every 30s, five times.

Enzyme activity was expressed by OD change per minute (ΔA ₃₉₈ / g min). The change of 0.01 in OD value per minute is expressed as 1 multienzyme oxidase activity unit (U).

In the formula:

Δ A ₃₉₈ ——OD change value within the reaction time;

V _T - the total volume of the extracted enzyme solution (mL);

- fresh weight of the sample (g);

V _s - the volume of enzyme solution used in the measurement (mL);

t— response time (min).

Test Results and Analysis

The sensory evaluation results of the fresh-cut thorn buds on the 6th day of storage are shown in Table 1. It can be seen from Table 1 that on the 6th day of storage, the untreated fresh-cut thorn shoots were browned, with a strong rotten smell and a large number of water-soaked blocky areas. Due to severe dehydration, the texture became soft, and some areas appeared rotten The fresh-cut thorn buds of embodiment 1 and embodiment 3 change similarly, and the color is dark, and the unique aroma component fades, and dehydration phenomenon occurs, and freshness reduces; The fresh-cut thorn buds of embodiment 2 still keep the original Some fresh condition. This is because the components in the coating solution have anti-oxidation, antibacterial and hardening effects, and the coating solution will form a film on the surface of fresh-cut thorn buds after drying, preventing external factors from damaging it, ensuring Long-term storage of fresh-cut shoots.

Table 1 Sensory evaluation results of fresh-cut thorn buds on the 6th day of storage

Sensory score (points) Freshness color odor texture Exterior total rating unprocessed 3.5 3.6 3.9 3.8 3.4 Extremely poor quality, sample completely spoiled, inedible Example 1 5.6 6.3 5.7 5.8 6.1 The quality is average, although there are defects, but it does not affect the consumption Example 2 7.9 8.2 7.1 7.2 8.7 Good quality Example 3 6.1 7.3 5.9 6.8 7.2 The quality is average, although there are defects, but it does not affect the consumption

See Table 2 for the microbial detection results of the fresh-cut thorn shoots stored on the 6th day. As can be seen from Table 2, the total number of colonies, mold and yeast counts of untreated fresh-cut thorn buds are far higher than that of embodiment 1, embodiment 2 and embodiment 3, and the total number of colonies of the fresh-cut thorn buds of three embodiments is low Both mold and yeast counts were below 5 on average 100. This is because the coating makes the fresh-cut thorny shoots form a protective film, which prevents the invasion of microorganisms, and also inhibits the growth and reproduction of microorganisms.

Table 2 Microbial test results on the 6th day of storage of fresh-cut prickly shoots

sample Total number of colonies (CFU/g) Coliform bacteria (MPN/g) Mold count (CFU/g) Yeast count (CFU/g) unprocessed Greater than 100, the number cannot be counted not detected 12 7 Example 1 78 not detected less than 5 less than 5 Example 2 55 not detected less than 5 less than 5 Example 3 64 not detected less than 5 less than 5

The changes in the weight loss rate of fresh-cut thorn buds during different storage periods are shown in Figure 1. As can be seen from Figure 1, with the prolongation of storage time, the weight loss rate of untreated fresh-cut thorn shoots increased sharply, while the weight loss rate of fresh-cut thorn shoots of Example 1, Example 2 and Example 3 treated by coating film increased. slow. It shows that the coating treatment slows down the evaporation of water and maintains the freshness of the fresh-cut thorn buds.

The changes of chlorophyll content in fresh-cut thorn shoots during different storage periods are shown in Figure 2. It can be seen from Figure 2 that with the prolongation of storage time, the chlorophyll content of untreated fresh-cut thorny shoots decreases sharply, while the chlorophyll content of fresh-cut thorny shoots of Example 1, Example 2 and Example 3 after coating treatment decreases. slow. This is because after the prickly shoots are trimmed, their tissues are exposed to the air, and the chlorophyll is decomposed, changing from green to yellow or brown; while the coating treatment reduces the decomposition rate of chlorophyll, and better maintains the fresh-cut prickly shoots. color.

The changes of catalase activity in fresh-cut thorny shoots during different storage periods are shown in Figure 3. As can be seen from Figure 3, with the prolongation of storage time, the catalase activity of untreated fresh-cut thorny shoots increased sharply, while the fresh-cut thorny shoots of Example 1, Example 2 and Example 3 treated with film coating Catalase activity increased slowly. Catalase is the protective enzyme of the superoxide free radical scavenging enzyme system and one of the important enzymatic defense system tool enzymes in the thorn buds, which can effectively prevent the accumulation of free radicals in the fresh-cut thorn buds. After the untreated fresh-cut thorn buds were trimmed, the tissue was injured, and the self-protection system of the thorn buds activated catalase; while the fresh-cut thorn bud tissues treated with the film were protected to make the catalase activity The change was relatively slow, which indicated that the coating treatment had a protective effect on the fresh-cut thorn buds and prolonged the storage time.

The changes of malondialdehyde concentration in fresh-cut thorny shoots during different storage periods are shown in Figure 4. It can be seen from Figure 4 that with the prolongation of storage time, the MDA concentration of untreated fresh-cut thorn buds increased sharply, while the fresh-cut thorn buds C Dialdehyde concentration increases slowly. Malondialdehyde is one of the end products of membrane lipid peroxidation. The higher its content is, the more serious the damage is to the structure and function of the cell membrane, and the permeability of the membrane is reduced. After the untreated fresh-cut thorn buds were trimmed, the cells were seriously damaged, which caused the rapid increase of malondialdehyde; while the fresh-cut thorn buds treated with the coating film were protected, which delayed the peroxidation of membrane lipids and ensured their physiological and biochemical of normal progress.

The changes in polyphenol oxidase activity of fresh-cut thorny shoots during different storage periods are shown in Figure 5. It can be seen from Figure 5 that with the prolongation of storage time, the activity of polyphenol oxidase in untreated fresh-cut thorny shoots increased sharply, while the fresh-cut thorny shoots of Example 1, Example 2 and Example 3 treated with film coating The activity of polyphenol oxidase increased slowly. Under aerobic conditions, polyphenol oxidase can oxidize catechol to generate quinones, and further polymerization of quinones will form melanin, which will cause enzymatic browning of thorny shoots. After the untreated fresh-cut shoots were trimmed, the membrane system was destroyed, and the tissue was exposed to the air, which increased the activity of polyphenol oxidase; while the coating treatment prevented the contact of oxygen with the fresh-cut shoots, inhibited the Phenolic oxidation to maintain the color of fresh-cut thorn buds.

Claims (10)

1. A fresh-cut prickly bud coating material, characterized in that the film-forming liquid is mixed with the following mass fraction raw materials: 0.01%～0.05% clove essential oil, 0.1%～0.5% ethanol, 0.75%～1.75% carboxymethyl Chitosan, 0.5%~1.5% calcium lactate, 0.5%~1.5% glycerin, 0.5%~1.0% sodium carboxymethyl cellulose, the balance water. 2. fresh-cut thorn bud coating material according to claim 1 is characterized in that in the preparation of coating solution, first 0.05% clove essential oil is dissolved in 0.3% ethanol, then with 0.75% carboxymethyl chitosan, 0.5% calcium lactate, 1.0% glycerin and 1.0% sodium carboxymethylcellulose solution were mixed. 3. according to claim 1 and 2 described fresh-cut prickly shoots coating materials, it is characterized in that in the preparation of coating solution, each component will be homogenized when mixed, the time is 6min, and the homogenization speed is 4000r/min . 4. A method for fresh-cut fresh-cut thorn buds coating film, is characterized in that comprising the following steps: (1) Selection: select fresh thorn buds without mechanical damage and no pests and diseases; (2) Cleaning: Rinse the thorn buds obtained in step (1) with clean water; (3) Arranging: remove the prickles from the thorn buds obtained in step (2), trim and cut into sections; (4) Preparation of coating solution: by mass fraction, 0.01% to 0.05% clove essential oil, 0.1% to 0.5% ethanol, 0.75% to 1.75% carboxymethyl chitosan, 0.5% to 1.5% calcium lactate, 0.5% ～1.5% glycerin, 0.5%～1.0% sodium carboxymethyl cellulose, the rest water, mix to make film-forming solution; (5) Coating: put the fresh-cut prickly shoots obtained in step (3) into the coating solution obtained in step (4) for dip coating; (6) Drying: Take out the dip-coated fresh-cut shoots obtained in step (5), drain the dip-coating solution, and dry in the air; (7) Storage: The fresh-cut prickly shoots obtained in step (6) are subpackaged and stored. 5. The method for fresh-cut fresh-cut thorn sprouts coated with film according to claim 4, characterized in that washing in step (2) is carried out with clean water at 10°C to 15°C. 6. The method for fresh-cut fresh-cut thorn buds coated with a film according to claim 4, characterized in that trimming and cutting into sections in step (3) is trimming the thorn buds to a length of 5 cm to 7 cm. 7. The fresh-cut fresh-cut thorn buds coating preservation method according to claim 4, characterized in that the temperature of the coating solution in step (5) is 10°C to 15°C, and the dipping time is 1 min to 3 min. 8. The method for fresh-cut fresh-cut thorn sprouts coated with film according to claim 4, characterized in that the storage temperature in step (7) is 1°C to 5°C. 9. fresh-cut fresh-cut fresh-cut thorn sprout coating fresh-keeping method according to claim 4, is characterized in that the steps are as follows: (1) Selection: select fresh thorn buds without mechanical damage and no pests and diseases; (2) Cleaning: Rinse the thorn buds obtained in step (1) with water at 10°C to 15°C to remove dust on the surface; (3) Finishing: remove the thorns from the thorn buds obtained in step (2) with a sterilized sharp instrument, and trim the thorn buds to a length of 5cm to 7cm; (4) Preparation of coating solution: 0.01% to 0.05% clove essential oil, 0.1% to 0.5% ethanol, 0.75% to 1.75% carboxymethyl chitosan, 0.5% to 1.5% calcium lactate, 0.5% ~ 1.5% glycerin and 0.5% ~ 1.0% sodium carboxymethyl cellulose are mixed to make a film-forming solution; (5) Coating: put the fresh-cut prickly shoots obtained in step (3) into the coating solution obtained in step (4) for dip coating; (6) Drying: Take out the dip-coated fresh-cut shoots obtained in step (5), drain the dip-coating solution, and evaporate the surface water by natural drying; (7) Storage: Pack the fresh-cut thorn shoots obtained in step (6) into plastic boxes and store them at 1°C to 5°C. 10. fresh-cut fresh-cut fresh-cut thorn buds coated fresh-keeping method according to claim 9, is characterized in that the steps are as follows: (1) Selection: select fresh thorn buds without mechanical damage and no pests and diseases; (2) Cleaning: Rinse the thorn buds obtained in step (1) with 10°C water to remove surface dust; (3) Finishing: remove the thorns from the thorn buds obtained in step (2) with a sterilized sharp instrument, and trim the thorn buds to a length of 5cm to 7cm; (4) Preparation of coating solution: according to the mass fraction of 100%, first dissolve 0.05% clove essential oil in 0.3% ethanol, then mix with 0.75% carboxymethyl chitosan, 0.5% calcium lactate, 1.0% glycerin and 1.0% carboxymethyl The base cellulose sodium solution is mixed, each component should be homogenized when mixing, the time is 6min, and the homogenization speed is 4000r/min; (5) Coating: put the fresh-cut thorn shoots obtained in step (3) into the coating liquid obtained in step (4) for dip coating, the temperature of the coating liquid is 10°C, and the dipping time is 2 minutes; (6) Drying: Take out the dip-coated fresh-cut shoots obtained in step (5), drain the dip-coating solution, and evaporate the surface water by natural drying; (7) Storage: The fresh-cut thorn shoots obtained in step (6) were packed into plastic boxes and stored at 4°C.